Speakers: Ceramic, Alnico, and Electrodynamic....a Basic Discussion
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- Опубліковано 1 жов 2024
- This video is a basic discussion of the construction and function of three types of audio speakers: Ceramic, Alnico, and Electrodynamic. Topics include voice coils, wattage, impedance vs resistance, electromagnet vs permanent magnet, voice coil testing, effects of signal polarity on cone motion, field coils, and humbucking coils. To demonstrate construction principles, a speaker is dissected and the component parts are examined and explained. This presentation is best suited to individuals seeking a basic understanding of audio speakers.
Here is a link to the 1940 National Dobro video: • 1940 National Dobro Am...
Here is a link to an EIA Code site (to identify speaker and component manufacturers): www.thespeakers...
If you enjoy videos featuring classic vintage tube amps, jukeboxes, bizarre homebuilt electronic marvels, and clear, concise technical presentations, then please subscribe to my channel. You will gain immediate access to 100 additional videos, and (if you activate the service) you will be notified each time a new video is posted. Thanks for watching !!!
I just learned more about speakers in 25 minutes that I have in all my 62 years of doing other stuff. Thanks, Uncle Doug and Rusty :-)
You're welcome, QF. We're glad the videos are informative :)
Absolutely, same here. Just took the right guy to come along.
A few things I learned working at Cerwin-Vega (many years ago):
1. We always called them "spiders" even though they don't look like arachnids. Interesting to learn the source of the term! Their main purpose isn't to keep dust out, but to keep the voice coil centered in the magnetic gap.
2. Besides burning out the voice coil, another cause of failure due to excessive power is overexcursion, which can cause the voice coil form to "bottom" in the magnetic structure, often ruining it (you'll typically hear a loud "crack" if this happens). Open-back cabinets do nothing to prevent this, though you're right that the stiff suspensions of guitar speakers make it less likely. Still, playing a bass with a powerful amplifier through guitar speakers in an open-back cabinet is inviting trouble!
3. Overheating the voice coil may not melt the wire, but it can soften or burn the glue holding the coil together, allowing the coil to "throw a winding" into the gap. Time for a new voice coil.
4. Magnet size by itself is overrated. My boss used to ridicule the ceramic magnets found in cheap speakers as "dried mud". They could advertise heavy magnets when what actually matters is magnetic field strength.
Excellent comments, Rob. I had a personal experience with #3 fairly recently. Thanks !!
Fascinating.
Your Presentation of "Speakers: Ceramic, Alnico, Electrodynamic....a Basic Discussion" is excellent
I've been on a quest to discover the reason behind the magic of Alnico magnets
I climbed to top of the mountain to receive wisdom and Uncle Doug bestowed
Thank you
It was a pleasure, Damon. I'm glad you enjoyed it.
Already have one! (Beer). That was me! Thanks Uncle Doug.
Amp guys....beware of field coil amps and messing inside the speaker area of an amp. B+ voltage on these amps can run upwards of 450vDC. It can kill or shock you at best if you move a wire that is carrying B+ and touch a spot where the insulation is missing. Always be careful working on/near tube amps as they often carry high voltages and because of capacitors, can actually store voltages for some time, even when off....
WE thank you for the incredible amount of time & preparation you must need to compile such high quality, interesting videos. And I feel almost ashamed to post a comment since I see that, on top of that, you also take the time to respond to a lot of them !
I have only one question : I am going to replace a 15 speaker in a Fender Excelsior amp (the original speaker is very not very good and underpowered). Problem : this original speaker has no polarity mark.
Is polarity relevant in a 1-speaker amp? (I've been told it doesnt, that I could put any wire on any terminal of a single speaker) , but if it does, how do I know which wire from the amp section is the hot one (they are both black) to connect to the new 15 Eminence (which does have a polarity marking) ?
BTW, I started watching your canal by viewing your fine vid on pine cabinet construction, since the Excelsior baffle design actually bars maybe 1/5 of the speaker hole area. I might have to build another cabinet since I'm expecting some trouble with the new speaker which is not only better, but also much more powerful (100W against 15 w for the original speaker !). I suspect the greater air flow will need full free space to avoid any parasite vibration (I know from a previous similar experience).
Cheers
+lust4bass You're welcome, L4. Hearing such nice comments from viewers makes it all worthwhile. Polarity does not matter with a single speaker. You can wire it either way with no noticeable effect. Instead of building a new cabinet, can you simply enlarge the hole in the front baffle? Thanks again for your nice comments and good luck with your modifications.
+Uncle Doug Thank you for your quick answer, Uncle Doug. Maybe you are not familiar with the Excelsior cabinet structure. The diameter is OK, it is the "Art Deco" bars in front of the whole that might cause a problem. I've read comments that upgrading the speaker could be followed by undesirable sounds/vibrations. We'll see anyway when I make the replacement, which I can make now that I have the useful info you've just given to me. Greetings.
You're welcome, L4. Good luck.
+Uncle... Isn't the power going to the speaker doing the work of moving the cone? How much of that power is being lost to heat?
Actually speakers are not very efficient, only about 2 -5 %. EV's and JBLs can be close to 10%. In a way the sound itself can be considered increasing the heat of the air, because it is increasing the average velocity of the air... but the main loss is due to the long wavelengths of sound The wave length of 100 Hz for instance is around 11 feet . So the 1/4 wave distance is around 2ft and 7 inches., The speaker cone moves a lot and doesn't couple to the air,. also the amount of work that the magnetic fields can do, versus how much the electron flow just heats the wire.
Interesting & informative! One thing I've always wondered about AC waveforms ending up pushing/pulling a cardboard cone is the conveyance of 'Timbre'. I understand harmonics & sound synthesis, but still, on an old vinyl LP, how does an oboe or piccolo tone come thru with strings & horns, with just a needle scraping sides/going up/down? Analogous, yes. But still, 1 needle or 1 read head or 1 bitstream ultimately goes to paper cones pushing air against my eardrums. Oboe timbre still there. Miraculous! God does love us!
Thanks. It is indeed miraculous, Bob.
Uncle Doug and Rusty, rule...
Thanks, F86. It's always good to hear from you :)
Uncle Doug is an example of careful work and knowledge of all aspects of the process. He is an inspiration to me and many others.
He is so good at what he does, he makes it look so easy!
What do I do, and why am I responding to your comment?
I rebuild old jet engines, and right now in my shop I have two different engines that powered the F86 Sabre...
A J47 -13, going back into an F-86A, and An Orenda 14, going back into a Canadair Sabre 6.
My biggest project to come: I want to scratch build a tube amp following Uncle Doug's amazing guidance.
I always thought the name "Spider" was coming from "Spider web", because it act like a spider web with the spider (the voice coil) in the center, waving but acting like a suspention.
And like always, thanks for all the videos, I'm curently re-watching all the videos! ;)
I tend to agree with your explanation for the application of the word "spider", Jeremy. In early speakers, the spider had multiple curved arms to hold the voice coil, and did indeed look like an arachnid swirling while being flushed down the toilet.
Mylar? A mylar voicecoil?? Perhaps kevlar, yes.
Mylar works well for small high frequency use. Mylar works well as a suspension material on larger format compression drivers, such as Radian's excellent sounding pro units.
My apologies if I'm unaware of any units that found a good use of mylar for a voicecoil.
Cheers
You're probably right, PR. The material closely resembled a roll of Mylar tape. I understand most are made of aluminum, Kapton, or even fiberglass.
Thanks so much for this and all your videos. They/you rock!
My first amp as a kid was a cheap tube amp (maybe Danelectro) with an 8" speaker with a transformer attached to it. I decided to stuff a 12" 8 ohm speaker in the cabinet with no knowledge of matching the circuit. No idea what that little transformer was for. Turned it on and rocked out for about ten minutes until the amp smoked itself to silence. Great fleeting sound! Ha ha
A lesson learned about matching speaker to OPT impedance :)
the national Dobro, has the resonator box, it's principal design, before there was electricity~ very shocked to see that name on electrical stuff~
Dobro referred to the Dopyera brothers, Jay. It was used to name their resonator guitars, but also to name some of their other products....like National Dobro amplifiers.
I started my hobby with several name brand tube televisions and radios from the forties, fifties, early sixties. Hunts, Arvin, Whitney and some of the call letters of the station were embossed on the old ivory buttons. Most of these vintage units contained electro magnet or dynamic field coils and the sound was amazing. During that era..I came across a type of tweeter on a tube hifidelity radio turntable unit that I had never seen...a thin curved or arc of metal mounted to a flex plate with what looked like either carbon fiber or bakelite fingers behind the arc that had one wire connected to the arc and one the the carbon fingered bracket. A huge transformer was mounted on the 12" speaker and fed both the woofer and this unique tweeter through what I read as a non polarized capacitor and a ceramic wire wound resistor with a n adjustable slide ring wiper, which may have been the beginning designs of r c filtering??
My guess circa 1958, 1960 ..no loctal or octal tubes for dating..all 7 and 9 pin if I recall correct. 6beg, 6bag, 6v6g, 12ax7 philco and sylvania tubes.
Now nearing retirement the itch is back to restore some of these older recievers and maybe ham radio versions.. who knows.
I posses a set of vintage hard bound tv radio repair cyclopedias and manuals from the early fifties an pristeen shape that is up for grabs..
That tweeter sounds like quite a piece of engineering, Gary.....almost like a mini-plate-reverb for high frequencies :) Thanks for your interesting comments. Perhaps a viewer will be interested in your offer of manuals and books. Best of luck.
Got a full life with so much to do... and it just got fuller after discovering this channel. Uh oh.
Join the club, LS. Rusty and I are busy from dawn to dusk, and never seem to be finished.
Fascinating stuff! I was looking for info about the speakers in my Music Man 210 HD 130. Thanx very much for a great class. :-)
Y'know, I thought I knew just a little bit about speakers after modifying or replacing elements in almost every speaker system I've owned over the past 40 years. Doug, you beat me with a stick, and gladly so. I had no idea how in-depth one could get in this oh-so-not-sometimes-esoteric medium. Hats off to you, sir! ~ S ~
Wow....thanks so much, TC. Rusty and I really appreciate your kind appraisal, and wish you all the best (or "beast" in Rusty's case :)
Uncle Doug You recall our exchange concerning those old ceramics out of your previous project. You are absolutely right, they don't hold their age at all. Somehow I was hoping that . . . never mind. It is what it is.
Greetings, "Paleface" (if my rudimentary Spanish is correct). Yes, I recall your inquiry about the Newcomb speakers. I believe they are a good example of speakers designed purely for midrange, with small voice coils & magnets, and cones with rather soft suspension. Which is fitting, since the Newcomb E-20 was a public address amp. On their best day, they were probably incapable of accurately portraying frequencies below 200 or 300Hz. This is not a result of their age, but rather their design.
On the other hand, the Jensen C12Q in the video is quite the opposite. Once the voice coil has been replaced and despite its age, it will function as well (or better) than many new speakers, due to its significantly larger VC & ceramic magnet, and much stouter cone suspension.
The 64,000-dollar question (how's THAT for a dated reference!) Regarding the 'humbucker' electrodynamic speaker: If the hum is neutralized, wound'nt the magnet field ALSO be neutralized? (21:05)
No, not any more than the signal is neutralized in a humbucker guitar pickup. The humbucking winding in an electrodynamic speaker is relatively small compared to the huge electromagnetic winding and effectively neutralizes the 50 or 60Hz hum picked up by the large magnetic winding, which acts like an antenna for EMF, without affecting the much, much stronger music signal passing through it.
Your videos inspire me to learn electrical engineering on the free MIT courseware online. You're a very good teacher
Thanks, NR. By all means, pursue your goals.
The best videos I have ever seen. thumbs up.
Thanks so much, Mr. Mac. Rusty and I are glad you enjoy our videos :)
Fantastic
Oh man I love this stuff... basically I'm having to endure my own ignorance, realise the weight of it as both an impeller and a detractor. I haven't done this stuff for ages and, with that chasm of time between, on one hand it's almost as if I've given myself a time for the ideas to actually be understood but at the same time realise a sense of stubbornness I'd used to bolster myself, back in those dim and dark days, just to go forward. Gosh... let's hope this time around I take more time to appreciate the ignorance I undoubtedly have now and use it to find that sense of intuition where I might know it's actually making other futures even more difficult... maybe that's what wisedom and humility actually are? Cheers utmostly Mr Uncle Doug! As an aside I did some pickup making way back then, any old wire and any old magnet, but I did kinda notice a difference within the makeups of different magnets creating fields. Alnico, as it were, seemed somewhat more attune to the human ear and felt unable to be precise as frequency went both higher and lower whereas something like neodinium, those little pellets of it were starting to become available, felt more precise in the sense that in something like a bass pickup it was very much able to give clear lows whilst also bringing a very clear 'fingerwork' sense, but in the mids it felt sterile ... interesting.
Thanks for sharing your ruminations, Sean. Best of luck with your renewed interest in speakers and tube amplification.
Very nice job sir
Not even sure how I came to watching this video but so interesting and well presented. Have much better general understanding of speakers and that makes for 20 mins. very well spent. Thanks!
Thanks for watching, Hal.
Awesome. I learned a ton! Thank you for sharing.
Chris Fite You're welcome, Chris. Glad you liked it :)
I can not resist the charm of the old bad boys and his tones... this is precious info thanks Doug and Rusty with your wishbone :)
You're welcome, Rene. We're glad you enjoyed the video :) ^. .^
another permanent magnet speaker is neodymium. it's magnet is small as well and is being used more and more on high end modern speakers.
You're right, Do. They create a powerful magnetic field for their size and are becoming more common as costs come down a bit.
interesting that they would make forms out of titanium as it's a terrible heat conductor.
I think aluminum is by far the most common, Do, and it's a wonderful conductor of heat.
I have an old alnico 15 inch speaker from an musicman. It sounds so much better than ceramic speakers
You're a great teacher Uncle Doug!!!! Thank you!!!
Thanks for the nice comment, Woody.
Understanding is a wonderful thing, and your videos bring it to a new level. Rusty must have underestimated how much more there is to learn about speakers.
Thanks, BT. Like most 16-year-old's, Rusty thinks he knows it all.....and that the world revolves around HIM. Hopefully, SOME day he'll grow up, move out, and get a job. THEN he'll discover how little he REALLY knows.....Oops, sorry, I had a flashback to a family discussion back in 1963 :))
Thank you Uncle Doug. Your videos have been so useful to me. I restored my dad old technics speakers. Thanks for your time and teachings.
You're welcome, Jose. We're glad the video was helpful.
Thank you Doug for taking the time to make these videos. They are very enlightening for us, the amateurs.
+Angel Escobar You're welcome, Angel. I'm glad the videos are helpful :)
Excellent indeed!
The talk of turkey magnet sandwich and can of tuna is making me hungry! Great video! I appreciate you sharing your knowledge and I like your sense of humor too.
👍🇺🇸❤😁
I was going to add an after dinner speaker to my quiet, at home evening amp. Guess I'll rethink that... Gracias, señor.
that was a very loving approach to what we always have wondered~ pressure needed, or we have failures, sorta like backpressure for the engine~
Thank you so much for creating/posting this video. In the past, I tried to read about speaker design but had a tough time visualizing and interpreting the typical speaker cutaway drawings that you see in books. Your video is so much more effective in explaining the various speaker components. Well done!
+DaMaxchi You're welcome, DM. Rusty and I are really glad the videos are helpful.
What a beautiful presentation. A pleasure to watch and listen to.
Thanks so much, Bill. Rusty and I really appreciate your nice comments.
Sorry for this interruption @ 9:00 and up. Please do not attempt to do it with junk parts. As there are some companies around which sale frist class parts for these kind of repair. You can get voice coils, membranes, spiders, or even a whole "recone kit" for speakers.
To get the best out of this kind of real (=true!) Vintage speakers, go for a new voice coil or a recone kit...if you hear the reconed speaker working again it´ll probably blow your mind away, as it´ll sound like a NOS type!
Usually Pro Companies (EV,JBL,RCF,Beyma,Eminence....) provide komplete recone kits and/or parts to repair speakers. As in Pro usage a LF (=bass) speaker is rated for 1000 hrs. of service and then needs to be replaced or repaired due to wear out.
I was into this almost 20 years ago, as i was a part time repair technican in a Pro Audio rental company. I reconed a lot of Speakers those good old days, and had lots of fun with the weared out cones before. To get it out easily we usually charge a bunch of high rated Caps in paralell (4700µF/450V) and dischage it through the voice coil. The cone come out easily. Sometimes it just hits the roof;)
But don´t try this at home if you do not have any experience in HV as when the Caps are charged they will kill you without any doubt...
Don't worry, TC, on a good speaker like this, I would only use the best quality voice coil. I love your story about blowing the cones out of old speakers.....this would make a great video. I can imagine a group of people running around in a workshop, shooting at each other with speaker cones.....sort of like Salvador Dali's version of a paintball battle. Great stuff !!
Great video. I wish I watched it a couple of years earlier, when I was trying to identify the speaker that came in my Victor projector speaker cabinet.
+Gaita Ponto Thanks, GP.....glad you enjoyed it :)
Okay, I'll bight. Could you have a neodymium magnet speaker?
Great videos Uncle Doug. Keep it up. Thanks.
1musicsearcher Yes indeed, 1ms, in fact they currently exist. Here is a JBL site that discusses the advantages: www.jblpro.com/www/jbl-story/innovation/technology/material-innovations/neodymium-magnet#.VRzJ0o7bX3g The main drawback is the cost, which may come down once they are more widely available.
congrats on 100th videos..:) pretty cool to see inside of that stuff! oh man I see ive made mistake of putting a too small watt speaker with bigger out put..i see why it started going out..lol I was young when I did it tho. I watched the whole thing..cool speakers you have there..:)
Thanks, UG. I'm glad you enjoyed the video :)
The field coil is reminiscint of the universal AC/DC brushed motor used in Lionel trains. Using a field coil instead of a permanent magnet allows for the magnetic field to be reversed. An electromechanical device on the locomotive would reverse the field coil with respect to the motor brushes to reverse the rotation of the motor, thus reversing the locomotive. This is how they could reverse while using AC power to the track. Most DC trains just used permanent magnets and then reversed the polarity of the power on the track.
Very interesting, Greg. I had a Lionel 0-27 train set as a kid, and the locomotive had reverse. Thanks.
what about neodymium magnets used in guitar speakers?
how do they measure up with cermic,alnico??
are they better or just lighter in weight?
+Kwesi Henderson Greetings, Kwesi. From what I can gather, the benefits of Neodymium magnets, used primarily in bass speakers so far, is mainly due to their much lighter weight (for the same or greater magnetic flux). Here is a site that discusses the topic in detail: forums.fender.com/viewtopic.php?f=23&t=90032
HI Doug, been awhile since a video. Hope everything is okay with you. Thought about you recently when i came across this guy who makes valves / tubes. Wonder if you have come across him in your travels, glasslinger's channel Take care and all the best to Rusty. Looking forward to more inspiring and informing videos. Colin
Greetings, Colin. It's always good to hear from you. Rusty and I are in excellent health and taking a little sabbatical from video making. I've been working on a sand rail (car) that I drive in the desert (like a maniac), while trying to think up new video topics. Hopefully, we will have something ready to upload in the near future. Thanks for thinking of us :) ^. .^
P.S. Yes, the guy who makes vacuum tubes from scratch is truly awe inspiring. This is REALLY getting down to basics. I guess the next step would be to take up blacksmithing and make your own hand tools :)
As always, thank you for taking the time and effort to produce these videos for all of us eager learners, you're a great resource for all of us want to be luthiers and amp Smyrhe's!
Wonderful job.
Compulsor You're welcome. Thanks for all the kind words. Rusty and I are glad you enjoy our videos.
This was very helpful. Are there problems with under powering speakers? Over powering, you melt the voice coil, what happens when you under power?
Nothing that I can think of.....other than low volume.
Thats what I thought, not what I was told by an obviously uninformed guitar player
Just for fun, ask him if he always plays at full volume to avoid "harming" his speaker, Sim :)
haha, I will do that
I've got a pair of Celestion G12T-100's that both sound very weak and quiet, lacking all bass when I test them (individually). Any idea what's wrong?
If you're testing them out in the open air, not in a cabinet and attached to a baffle, just about all speakers sound awful. They must be installed properly to work properly.
I believe "tinsel lead" is the term you are looking for. Had to change a bunch in high power car audio speakers.
I believe I have heard that term used to describe the braided silver VC connection wires, TK. Thanks for the input.
Uncle Doug. I bought a 20W solid state radioshack PA amp. The rear has screw terminals for GRD (ground) 4, 8, 16 (ohms) and 70V. I am a guitarist and understand how to hook up a 4, 8 or 16 ohm speaker load. What is the 70V for???
Greetings, 65S. Public address amps are generally connected to a large number of speakers spread throughout a business, hotel, etc. Since impedance matching would be a nightmare with the regular 4 and 8 ohm outputs......can you imagine trying to calculate and match the impedance of 30 speakers in parallel?...... P.A. amps offer a 70V output that eliminates this concern. Each of the P.A. speakers has its own transformer mounted on its basket, and you simply connect them all in parallel using the proper speaker-mounted-transformer tap for the wattage of the speaker (i.e. 3W or 5W, etc.). The only concern is that the total wattage of the speakers cannot exceed the output wattage of the amp (i.e. 20 5W speakers is max for a 100W amp output). I hope this makes sense.
Thanx, Uncle Doug... That wuz another great instructional vid.
In your opinion, how does the electrodynamic stack up to permanent mag speakers as far as sensitivity and frequency response. Being a hot rodder at heart my brain sez, "Hmmm... how about adding a live/energized coil to an AlNiCo? ...which also begs the question: Does more gauze equal a better mousetrap?'" Thanx again and have a happy
I have never heard an electrodynamic speaker that didn't sound wonderful, but I have heard a few permanent magnet speakers that didn't. In general, the ED's are warmer and more mellow than their PM brothers. Magnet strength matters a lot in larger diameter speakers. It takes more force to move the greater mass and provide rapid changes of direction.
Doug. I just wanna say how great these videos are. I can't kiss enough butt. you know they are informative but they also are a grand departure from the usual self subservient fodder put forth by my fellow Generation Y'ers. on a personal note, I suffered an incredible personal tragedy this year and have enjoyed the comfort your videos ( and voice ) have brought me in tough times. I usually watch them late at night on my iPhone and have viewed almost every one. it feels good to get the mind on other things. I write this as my infant daughter lays next to me. she just fell asleep watching this video. apparently she comes from the Rusty school of compliments. anyways. thanks, and keep them coming.
Thanks so much, MH. At my age, I'll take whatever kisses (and compliments) I can get :))) On a more serious note, I'm sorry to hear of your recent tribulation, and am glad that my videos have been helpful and comforting. Rusty and I wish you and your infant daughter the very best.......
Hello there,
I have a blown Mark Levinson 6"*9" 8 ohm car speakers, wondering where to buy the parts ( voice coil, cone.....) to rebuild/ fix them?
Thank you,
I know of no elliptical reconing supplies, Sherif. You will most likely have to replace the speaker.
@Uncle Doug
excellent - I pretty much have vintage boxes to make all these combinations - I suppose I should have asked, what about amps (including boutique) where a ceramic and alnico play together? ( I will say ceramic is unforgiving for harp players, but anyway) - thanks in advance PS more small cones should?must portray more artifact.. fewer and larger cones should portray amp sag, and harp players of course want both.
Andrew, I am a firm believer in using different speakers within a cabinet, and a ceramic/alnico combo (literally) sounds great to me. Why must it be either/or ?? If each speaker has its own "voice", then four different, good-quality speakers in a single cabinet would sound like a four-member chorus, with much richer, fuller tone than four identical speakers simply reiterating each other. To be honest, I can't imagine why this isn't done more often.
Re cone diameter, it stands to reason that the smaller speakers are more responsive and offer more clarity than the big, lumbering 15" monsters.Twin 8's are a harpmeister's dream, ala Magnatone Melodier or Premier Twin-8.....but there is something primal and overwhelming about a pair (or better yet, a dozen :) big, nasty 15's roasting your face, i.e. at a CCR concert.
Another great video that clearly explains how audio works.
I am curious, how would rusty go about shimming the voice coil in the replacement procedure?
Thanks, Brad. Rusty and I are glad that you (and your handsome pal) enjoyed the video. Rusty's paws are a little sore from chasing the tennis ball, so I'm going to take over on this repair job.
To shim the VC, I will use small (about 1" x 2") pieces of developed X-Ray film, that are slid between the inner surface of the VC and the outer surface of the pole piece. You can also use pieces of business cards, post cards, etc. The coil is then vertically aligned with the pole plate, and first the dust cover and then the cone will be epoxied to the VC tube. After soldering (and testing) the wire connections, the original dust cap will be white-glued into place.
The job has been put on hold, however, because my local source of re-coning supplies has ceased to answer his phone.....I guess it's time to check the obituaries to see if I need to find another source.
Good job on the tutorial, UD.
Lawdy, this video has a long comment section -- 49 strokes on the PgDn key to get to the end -- but I am an inveterate comment queen, so here goes:
It took me awhile to get my head around the Electrodynamic speaker mechanism and how in the old amps they by default applied the Field Coil to also act as the choke in the B+ supply.
Step one: I needed to recognize that the field coil is stationary, and an electrically separate winding from the voice coil, and it is not electrically in series with the voice coil. There is a voice coil former with a winding fed from the amp output stage, exactly as is the case with a Permanent Magnet speaker. I missed that fact when I watched your video.
Step 2: Is this field coil not analogous to the (highlight, please) field winding on a solenoid? By running DC through it, doesn't it cause a constant linear displacement of the coil+cone? Same as what happens when you test a PM speaker by applying a battery across the terminals? Light bulb now starts to dimly light up. No, it's not analogous. The voice coil is magnetically neutral when no audio signal current is flowing through it, therefore no displacement inward or outward. A solenoid is different because the plunger in a solenoid incorporates a permanent magnet. Critical difference!
Step 3: Having the field coil do double duty as the PS choke has one drawback; there is a 60Hz or 120Hz hum signal across it, as is true for any B+ choke coil. That nastiness is going to be coupled into the voice coil. OH, so THAT's where the hum-bucking winding comes in. A bit of Googling reveals that the latter winding is wound on the VC former but in the opposite direction from the coil carrying the audio. It has fewer turns than the audio coil because it only needs to null out the hum imposed by the power supply.
Lastly, there is the matter of the strength of the field. That intensity is a function of the current flowing through the field coil. In a PM speaker, by contrast, that mag field intensity is a function of the moxie of the magnet. In a tube amp where the power supply current flows through the speaker's field coil, the louder you drive the amp, the greater the DC flow, thus increasing the strength of the field APPLIED to the voice coil. That's a neat synergy!
bminorscales Excellent observations and input, Bminor. Thanks for sharing this with us. It will further aid viewers to gain a fuller understanding of electrodynamic speakers.
What are your thoughts on the latest generation of lightweight speakers with neodymium magnets? Eminence for instance produces a 15" speaker with an 11-ounce neodymium magnet, the EPS 15C, that claims to have the tonal characteristics, frequency response and power handling of the much heavier Peavey Black Widow 1501-4 which has a 10-lb. ceramic magnet assembly. Many Peavey owners are switching to these neo speakers to lighten up their amps and save their backs. But some complain that the neo speakers are too treble-sounding. I feel that can be dealt with in the EQ. I find it much easier to cut treble that is there, than to add treble that isn't. I found that trying to "fake" treble that the speaker isn't really capable of reproducing, ends up sounding thin, "cardboardy" and boxy without body or substance.
All of your comments make good sense to me, MD. Any magnet that can provide the same or greater field strength with a substantial reduction in mass is an excellent innovation. I have no experience with neodymium magnets or their effect on tone, but I look forward to finding out for myself. Meanwhile, I'm all for them.
I think Rusty has a 'bone to chew" with you,,LOL! You were dissecting things before
you knew how to put it together? The ceramic magnets have a much higher flux density than the vintage AlNiCo
and that has some effect on the sound. The magnetic sets a N/S relationship to the voice coil which will change polarity
with the A/C of the changing music..and as they say in magnetism..like poles repel each other and opposite poles attract.
Seth Lover (Gibson) knew about the humbucker coil from these electro dynamic speakers and that launched his quest
for the humbucker pickup design. The metal around the field coil would be a soft steel that could be magnetized easily.
SuperCarver2011 Thanks so much for your informative input, SC.
What causes distortion to occur in the speaker. I like the celestial greenback for its distortion. Vs. the vaunted jobless e series which is crystal clear. Thank you for passing on your knowledge. Hi to the Jack!
I never thought that good speakers actually create distortion, Monte. Some break up sooner than others, but their job is to accurately portray the signals being sent to them.
A couple of niggling clarifications.
The material used for suspension at the outside of the frame is called the surround, whether it's foam or paper or cloth. And the cloth wires used to attach the coil wires to the terminals are called tinsel leads.
And I've enjoyed your videos thus far. Keep up the good work!
Thanks, Brandon. We will :)
I just stumbled across this video. I learned a lot. We need a part two on horns and tweeters. Usually the tweeter burns out first in a bookshelf speaker. The better bass guitar cabs have horns.
Some trivia. I grew up in Hope AR (25 miles from Texarkana) a mile from the original Klipsch company. This was early 70's not too long after he started. I had no idea what revolutionary speakers Paul Klipsch designed. What a wasted opportunity to beg for a job, any job just to be around this man and his work. At that time, Klipsch was in a run down, area of old, empty warehouses and a chicken processing plant. I used to play in and explore those abandoned warehouses. I don't know if Klipsch has moved since then. I'd assume they probably have.
I agree, Ray, about the lost opportunity to learn from the master. I specialize purely in vintage guitar amps and circuits, so I'm probably not the best source of videos on HiFi accoutrements, but I will keep your suggestion in mind for the future. Thanks !!!
French hi-fi freaks of Focal - jmlab made a flagship speaker with electromagnetic woofer in 2019 if I can recall right.
We need more EM speakers :)
I did not know speakers could be humbuckers... but I do know through the latest book I am reading... 12ax7s if using a 6 volt instead of 12 volt.... it is a humbucker love this book! gonna get his other two... after payday that is
seth sloppers Yes, I believe I discuss this in the video. The humbucker winding (wound opposite of the field coil) operates just like the one in a guitar pickup. It sounds like you are studying hard and making some good progress. We wish you continued success.........
Uncle Doug, I have a Vintage 1966 Blackface Fender Deluxe Reverb Amp all original, how do I distinguish the positive or negative wire coming from the amp that connects to the speaker. I know how to test the speaker polarity by using a small battery , but the wire from the amp itself is not labelled with negative or positive. Please help. And thank you.
Greetings, RS. I have some good news.....the polarity does not matter unless there are two or more speakers. Multiple speakers should be "in phase" so the movement of their cones is coordinated, but with one speaker, it doesn't matter. You can connect your DR speaker either way. One less thing to worry about :)
LOL! Back in the '60s, I built my own speaker cabinet with a Lafayette 15' woofer and a mid-horn and horn tweeter. The woofer looked just like the speaker featured at the very beginning of this vlog! What a nice memory trigger - Thanks!
You're welcome, Dave :)
@uncledoug This was a very information video. Thank you so much for posting it! I just purchases an early 40's GEB Lap Steel amp. The paper in the speaker is starting to crumble into dust. Can it be re-coned? Or is it possible to upgrade the speaker to a ceramic speaker like a newer Jensen?
What size is the speaker, Casey? If it's less than 10" in diameter, it probably can't be re-coned. If it's electrodynamic, it can be replaced, but the circuit must be modified to accommodate a permanent magnet speaker.
Great video..... this is fun stuff.
Possible orgin of using the term "spider" for the speaker's rear suspension.
In the world of round mechanical stuff.... the occasional part the manufacturer may call a "spider" is usually a device that's a round part, usually with legs from the larger diameter OD rim to the smaller duameter ID hub, (like a wagon wheel). A solid, disk-like part, without the legs, is usually called a diaphragm.
The most common function of either is keeping inner parts and outer parts aligned concentrically.
A speaker spider's primary function is to keep the coil former centered in the magnet's annulus and concentrically aligned with the rear speaker frame (and allows normal cone travel). The speaker's sorround or front suspension maintains the concentric alignment of the front of the speaker cone ( and travel).
The very old open speaker spiders MAY have allowed the voice coils to run a little cooler.... but the coil former was exposed, dust and dirt could eventually be an issue.
New disk style fiber "spiders" close that path to dust and dirt.
+dennis walsh Thanks, Dennis, and thank you for the very informative input.
Another outstanding informative and entertaining video. I think much of "electronics for guitarists" is watered down and often incorrect-its a pleasure to watch your videos, good info is worth its weight in gold.
I've become a vintage speaker junkie, and although they look cool and are historically accurate-its really all about the sound they get. I wonder if modern manufacturing would even be capable of making such speakers these days.
I think back to all those vintage recordings I love, and on occasion when I get that sound with old speakers/amp's-you kinda know you are hearing the real thing as it was made to be heard.
Keep up the good work, Im moving on to your speaker repair video next.
Thanks so much, Davo. It's great to hear that the videos are helpful and informative. I agree that the old, original speakers do capture the vintage sound we love to hear.
A bit of dirt or rust in the voice coil can completely stop a speaker from working. A New Year's eve gig in a small town in Wyoming was almost affected by such a thing. The horn of a PA speaker stopped working. No replacement was available. I carefully removed the driver from the horn and sprayed electronic cleaner into it because it was all I had. I re-assembled the horn and much to my surprise it worked! It worked for the rest of that tour, too. Be prepared!
Good point and an excellent on-site repair, Howard. Thanks !!!
Fabulous job Uncle Doug. My favorite line......."the magnet is the turkey", haha. Give Rusty a beef femur bone (available at meat counter in most grocery stores) and he'll never go back to that nasty rawhide again.
Thanks for the good advice and comments, TB :)
I was once told by John Dopyera jr. (R.I.P.) that his father had a licensing agreement with Altec-Lansing. Something to do with cone design. I haven't been able to verify his claim, but have no reason to doubt him either.
An interesting tale, Gorb. Thanks for sharing.
If you think AlNiCo speakers are light you should check out Neodymium speakers. Neodymium magnets are notoriously strong for their size.
+Matt Bowen That's what I understand. They can achieve the same or greater field strength as a ceramic or Alnico magnet....but at a fraction of the size and weight.
how do you "recone" a speaker? Can you repair rips? I have some speakers from the 30's and 40's that are so fragile- can the paper be fixed or preserved? I also have old speakers with capacitors attached to them- why? So many questions grasshopper.
Greetings, Anne. There are quite a few videos posted on UA-cam that show the reconing process step-by-step, and there are videos (including one posted by me) showing how to repair and reinforce old cones without actually replacing them. You might do a YT search for these topics.
The only reason I can think of for a speaker to have a capacitor attached is if the speaker is a mid-range or tweeter and the capacitor is a crossover (to send only the right frequencies to the speaker). Are you sure it isn't an output transformer that is attached to the speaker basket? See the one attached to the National Dobro speaker in my video.
I have put an order in for a pair of Jensen C12Q 16 ohm speakers. I have read good reviews on these. They apparently work well in the old style Fenders. I guess I'll find out once I've built her. I say her as my friend and I have been referring to the amp as 'her' for a little while. Ha ha I guess it's a guy thing. I thinks maybe she needs a name? I'm open to suggestions. Regards.
+Tony Kennedy I really like the new-issue Jensen speakers, Tony, and hope you feel the same. Best of luck with your project.
I enjoy watching these even thought I know little to nothing about electronics.. Hopefully through osmosis, I start to learn. I would have liked a brief comment on neodynium. thanks. K.
Welcome to our channel, Kirby. Since I only deal with vintage amps, Neodymium speakers are not part of our repertoire.....but I'll keep your request in mind for the future.
Do you feel any one of the three magnet designs is inherently better than the other, sound wise, or is this simply a subjective thing? Many people swear that Alnico's sound better than Ceramic, and I've always liked the sound of the few Field Coil ones I have, but I think I'm being persuaded more by the circuits than the speaker itself. What do you think?
I think it's largely subjective, Fred. If you demonstrated the three different magnet-type speakers to thirty people, you might end up with ten people liking each one of them.
Jensen says: "Alnico speakers produce a sweet, warm, vintage tone. They sound best at low levels and are great for blues, jazz and mellow rock. Alnico
speakers respond quickly, giving the musician a “one with the amp” feel.
They are world renowned as the premium speaker with the best tone".
"Ceramic speakers are designed to sound similar to the Alnicos,
and were first developed in the 1960s as a cost effective alternative to
the Alnicos. The advantage of the ceramic speaker is its ability to
handle more power as well as a player's front end pedal accessories.
Vintage Ceramic speakers are recommended for all types of music, and
sound best at loud volumes".
To me, electrodynamic speakers are generally very warm and rather bass intensive.....which I like. All the 1940's jukeboxes used them, and it's a tone that I really feel comfortable with.......but in the end, it's really up to the ear of the listener.
Rusty. the ultimate litmus test for Democrats. hehe (thought with love ) thanks doug. im so enjoying all this wonderful content you share. ohhh and im selling my OR100 and getting a hand made Purdy head from Peter in Alberta Canada . :) long live tubes !!!! and all things guitar. 😀
Thanks, Scott. Best of luck with your sale and new acquisition.
Wonderful Stuff! 6 people, or morons disliked this video! WTF! Haters are going to hate. Lovers are going to love. Uncle Doug is one of the best shows on UA-cam!!
Thanks so much, Marc. Disregard those poor, drooling lunatics who can't tell the thumbs up button from the other one.
Very nice presentation! Another interesting speaker type is the balanced-armature.
Thanks, CM. I am not acquainted with the speaker you mentioned.
Wow! Great Video! I just hope you don't run out of subjects to cover. Another 100 won't be too much to ask for, would it? When I was in Tronics school I worked a summer at a Goodwill reclaim action center in the electronics dept. I was always working on tube radios and TVs. One day a pair of beautiful Altec home stereo speakers came in and I tested them and found nothing wrong. So I boxed them up and send them to the store(in the same building) that my first wife worked at and at lunch told her to buy them for us. When I got off work I went to the store to get the speakers, my first wife told me this story. A man came in to the store and saw the speakers and asked if he could hook them up to see if they worked. He was asked if he knew how to test them the correct way and he replied he did, so he was left alone to try them out. A short time later my wife heard a loud pop and some of the lights in the shop went out so she ran to see what it was and after the smoke went away she found the man had cut off one end of an extension cord and had put the bare wires on the speaker terminals and plugged the other end in to a near by wall outlet. We'll my wife asked if he was gonna pay for the speaker and he replied, No! This speaker don't work! Thanks for these incredible videos. And tell Rusty to slow down on his chewing. Don't want him to lose his teeth!
That was a great story, Hubert. I wonder if that guy is available to test some of my vintage speakers ?? What a lunatic.....everyone knows you have to use 220VAC to properly test speakers ;)
It's always good to hear from you. Thanks for watching and posting a great comment.....I'll give Rusty your regards and warn him about proper dental care :)
well appreciate the presentation and learning of the filter choke use of the field coil and the humbucker. The independent power supply in field coil radio cabinets are a bit daunting. Inspiring stuff, look forward to more.. Appreciate the knowledge being shared. Thanks.
You're welcome, Anthony. I'm glad you enjoyed the video :)
Hi Doug I was wondering if it is possibly to convert a dod vgs 50 pedal that only has a 9v ps750 adaptor plug to a 9v battery hook up.my thought is you can't but not sure. thank you for any input you can give me on this.
I am guessing, since I have absolutely no experience with the pedal or adapter in question, but if the pedal functions on 9VDC from an adapter, then it should have no problem functioning with a 9VDC battery. The problem is the amount of current that the unit draws while operating. If the current demands are high, the battery would not last very long at all. I prefer using adapters, because batteries always fail....and usually at the worst possible time.
NIce vid for beginners.. they can learn a ton for older equipment in short order from this video format.
won't make them experts etc but thats hardly the idea.. it will easily help educate newbs however which is a big bonus imo
Thanks, K2 :)
I bought a 90's Technics electronic piano off Marketplace and the sound just wasn't quite right. I pulled the bass side speaker and all of the foam between the paper cone and the metal frame had disintegrated. The dust was laying on the bottom of the cabinet. It took me a minute to realize that this was not a new "floating cone" speaker but instead one that desperately needed to be replaced.
The foam cone surrounds do not last very long, Jon, but they can be re-coned.
Excellent all the way through. Only one piece of info I hoped for. Could you identify the north / south poles of the magnet? Is it simply the flat front and back, or something more complicated related to the doughnut shape?
Thanks, Jeff. The magnetic field is parallel to and centered around the axis of the pole piece, this is why the voice coil moves forward and backward within the field when the polarity of the voice coil reverses. Whether the front or rear of the pole piece is North or South probably varies in different speakers.....it wouldn't affect the function of the speaker.
This helped me save a pair of vintage pioneer speakers destined for the dump. One dead tweeter and one dead 12inch sub in the other. Found replacement coils and followed Uncle Doug's video and got them back up and running.
That's great to hear, S.
so I have 3 or 4 vintage jensen speakers I blew them up 20 yrs ago ,I guess playing to hard,but can have them fixed?Is it worth it
It depends on the speaker, Bob. If they were 1960's vintage Ceramic 10" to 15" Jensen's then yes, it would be worth it, especially if they were the original speaker(s) to one of your amps. If they were vintage Alnico Jensen's, then heck yes. You can order kits online to do the job yourself or there are places you could ship the speakers to for repair. Good luck !!!
Oh, BTW, Rusty has a short cone-shaped tail that wags...sometimes. Freq in Hz of tail? ;-) He's comically plump and suspected of being a 'furry turder'. Please don't take this negatively, because I too, and I suspect MANY others here on YT land, have cohabitated with furry turders. Why...wait...sniff-sniff...yep, one just went to the box to pudu...and missed! Grrr... Queue to old Willie Nelson song 'On The Floor Again...'
Maybe a weird question but: If you know the frequency range a given speaker is capable of, does it make sense to tune the tone stack etc. in the amp circuit so that it isn't really boosting or even outputting frequencies beyond the speaker's range, or is the payoff likely to be slim to nonexistent?
Greetings, WB. This is actually a very interesting question. Virtually all amps produce frequencies, harmonics, and overtones that their speakers are unable to portray, both at the high and low ends. Although it may seem wasteful to produce these un-heard tones, I don't think that narrowing the output band to only audible frequencies would have a positive effect on overall tone or output power......since more restrictive tone controls would simply be sending more of the signal to ground. You would not be increasing the overall output in the audible range.
Fantastic video you are a master teacher! You talk about the decision to move from alnico to ceramic as being a financial one. I also read that alnico contained strategic metal that was in short supply during WWII which contributed to the need for another magnet type.
Thanks so much, Troy. You make an excellent point about the limited availability of the Nickel, Cobalt, and Aluminum during the war, and the fact that after the war, the Ni and Co were primarily available from countries with controversial labor practices (see Adam Rainstopper's comment below). Both of these factors provided additional impetus for the shift to ceramic magnets....and the continued expense of obtaining these materials probably contributes to the high cost of Alnico magnets and speakers today.
Just had my 10 inch bose woofers refoamed...im learning some. im sure uncle Doug will help .
Keep watching the videos, Ed, and you will learn all the secrets of electronics.
I enjoy and lean something form your videos. I think you could added to this vides that the stronger the magnetic field for a given speaker the more efficient the speaker well be.
A good point, WC. Thanks for your nice comment and input.
So funny, when I toggle the like button, the value goes from 2k to 2.1k... now that IS significant :D
No kidding, PMD. Thanks !!!
Very informative.I worked for Radio Shack nearly 40 years ago and never got very much of the theory side of speakers. interesting to see an RS speaker in the video.
Barry Seaman Thanks, Barry. Glad you liked it :)
AAA+++ Video Doug , thank you very much for your academia. e.b.
You're welcome, N4 :)
I love these videos, and the fact that you sound like my Uncle Roger who got me into Amateur Radio and guitar amp teching only makes them that much better.
Thanks, TG. Glad to hear it :)
so f* good description about how a speaker works... nice to got here and learned more about them in such a very precised way, thank U 4 posted it!
Thanks, Aldo. Glad you enjoyed it :)
Om Uncle Doug. If one has an electromagnetic speaker and needs to change it to a regular speaker because it is tore up beyond repair how do you go about figuring out what the power supply needs in way of either ballast resistor or choke?
The ballast resistor should match the resistance of the field coil (even though DC resistance and AC impedance are not the same), or you can use a Fender filter choke for any of their larger circuits.
Man. I have reconed or even just re formed a few speakers when i could still see. One of my favorites was an old utah 15 out of a pa horn. It was an odd ohm 12 i think
Thanks for sharing, Jacob.
Instructive, interesting and nice video. Thank you very much! Grazie ❤
Glad you liked it, AA. Be sure to subscribe to receive new video alerts.