Minty Fresh '67 Bassman | Part 2 : Hidden Issues and the Deep Magic
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- Опубліковано 24 вер 2023
- The owner did a great job, but for some things, well, it takes a lot of experience and a deeper understanding of the circuits.
See part one here:
• Minty Fresh '67 Bassma...
I knew there was some things I have missed and only a qualified tech would be able to find. Great job Lyle.
You did a great job Scott. It’s just that beyond a certain point… well, let’s just say that while I do a lot of work on my own guitars (relief, intonation, wiring, general setup stuff) I don’t do my own fretjobs or neck resets.
Great job to both of you. I still have a long ways to go on amp repairs, but when I'm over my head, I like a pro to look things over too. I have a 1974 West Avalon reverb that needs my attention one day. Last time I ran it I was impressed by the clean tones. Now 20 years later I'm sure it needs all new electrolytics and tubes.
No kidding on the “Deep Magic”. Taking that beauty to the next level.
What an incredible difference once that cap was removed. Great demonstration. Thanks.
This is why you are THE MAN. Those little gems of knowledge that come from years of experience.
Loved the live demo with and without that cap! Talk about demonstrating a point! Nicely done’
I love watching you work on these old gems. Sad to say, they don't make them this good anymore. I wish I still had the Bassman I had in high school.
Always appreciate the “don’t try this at home” moments…even by an English major. Using "what it makes" is just your 40's gangster roots showing through. Top of the world, ma!
I LOVE that you quoted C.S. Lewis !
Thanks Lyle for showing the "art" of Amp design and repair. Really impressive understanding.
Excellent demonstration/explanation. Yeah that cap needs to come out.
There are few things in this world better than an expert who's not an ass about it. Thanks Lyle.
This is so timely, I'm restoring a '67 Bassman of my own at the moment. Literally wouldn't be possible without the knowledge I've gained from watching your videos, so thank you!
Know that you are not alone! Im working on my 67 at the moment and i have been chasing my tail for a week straight trying to sort out hum issues
Lyle has been a LD friend for years. His biggest influence, besides tech know-how, has been: just grab the guitar and be who you are. Nothing is gonna change that. Edit: almost 42k brother, seems other people agree with me.
Thanks Jaron.
But I have to ask - LD?
@@PsionicAudio Long distance?
@@PsionicAudio LD lethal dose
Hey LYLE you always amaze me with your deep knowledge and ability to work on tube amps! Thank you sir😊
I’ve got a 70’s Bassman 100 that I recapped. I Would love to see your work on one of those in the future! ❤
I just happened to be drinking a glass of milk when you said, "the electric tuba experience...", so you can guess what followed...
🤣🤣🤣
10 to 50 pf is large enough to control rf from my experience . The size is dependent on the tube used based on it bandwidth.
The owner will have an amazing amp once completed.
I found an old list of our suppliers from the 1920s-1977. More specifically these are potentiometer manufacturers. Sadly, we don't have this many quality choices anymore. (Unless you include ??? quality Chinese manufacturers.) Stackpole, Centralab, Clarostat, Daven, and Mallory all made good stuff.
Abbey
Aerovox
Allen Bradley
Alpha
Alps
Amphenol
Atohm
Basler
Beckman
Bi Tech
Borg (Warner)
Bournes
Calectro
Centralb
Clarostat
Copal
Colvern
Cosmos
CTS
Dallas
Dale
Daven
Duncan
Egan
Electro Scientific (ESI)
Electro Motive (EMD)
ETI
General Radio
Giannini
Helitrim
IRC
Liebherr (Germany)
Litton
Mallory
Matsushita
Maurey Instruments
Megatron (Gmbh)
Memcor
Mepco
Morganite
National Dial
Noble
Novoteknik
Pigeon
Ohmite
Omeg
PEC
Penny & Giles
Phoenix Contact
Piher
Plessy
Precision
Radio Spares
RCP
Reon
Sakae Altheris (Japan)
Samarius
Siernice
Spectrol
Stackpole
TOCOS
Techno
TRW
Vishay
Voltronics
Thank you, Lyle. Any thoughts on how the two transformers were kept so clean over the years? I can't remember ever seeing 50+ year old transformers that didn't have some amount of corrosion.
Learn something new everytime 😃👍👍
😎✌👍❤🖖
Of the auto-replies YT suggested to me, one is “Right on” and the other is “You got that right!”.
Nice to know JJ Walker still has a dynomite gig somewhere…
@@PsionicAudio
🤣
Groovy man✌❤
Always inspired
Thanks again for this video, Lyle, I’m learning a lot! May I ask a tech question? I noticed in the video the normal channel’s 2nd gainstage plate resistor being connected to the last B+ node, probably to reduce hiss through the mixing resistors? I tried this out on my 1968 Bassman Export (already did the ab165/aa864 hybrid conversion) and noticed two things: 1) 20 volt drop on the other 3 gain stages’ plates on that node and 2) a slight 100Hz hum introduced that wasn’t there before. I could put a larger filter cap in the last node and/or reduce the dropping resistor to-say- 22k. But I doubt it’s worth the trouble. The amp sounds great as is. What is your opinion? Thanks & greetings! Joost Overmars from the Netherlands.
This guy is the amp Rain man.
Sorry, I don't know your name. 80-year-old English guitar player since 1957 here. i built a couple of Mullard amplifiers in 1963 - the usual EF86, EL84 and EZ80 circuits. However, that's not why I write. Can I say that you have the most pleasant speaking male voice that I have heard from anywhere on your side of the pond. Which state are you from? I have driven in all 48 lower states. Thanks for an excellent series of videos.
Thank you Roger. That’s an extreme compliment if an odd one to have to live up to.
I’m from Jonesboro Arkansas originally but have lived in Memphis Tennessee since I was ten, with stints in Boston and Atlanta.
But you won’t hear much of any of those places in my accent. I did theater for years and wanted never to be limited by a regional accent. Occasionally I’ll be lazy and an I sound will become an AH sound but I try not to lapse.
A lot of Americans seem to think I sound Canadian but I don’t agree. Very different pronunciations and cadences.
I suppose I have whatever the American equivalent of relaxed RP would be.
@@PsionicAudio Thank you for coming back. You certainly don't sound either like Bill Clinton or Chet Atkins. We have been in your neck if the woods quite a few times, driving the River Road from Minneapolis to Norlins. Stayed in Nashville a few times for Fanfair. If there is a USA equivalent of RP then you seem to have it. Canadian? Ote and abote - I don't think so. Ha ha! Best wishes - Roger
thanks for letting us know it is safe to touch stuff inside while it's on. i will definitely do that tonight with no worries, may even scratch and sniff that white stuff on the backing of my fender champ....
I wish my hearing had the ability to discern between the tones. At a certain point my hearing just doesn’t work anymore. I’m disappointed that I can’t hear the lushness of pure sound. I could hear the difference after you removed the cap. Yeah.
I’m sorry man, it’s gotta be terrible when you love music and know you’re missing big chunks of it.
I have no pat advice, but please accept a virtual brotherly hug from a fellow music lover.
I just plug in headphones to hear the details better. I'm old too 🤣🤣
Lyle, I don't know if my process is valid or if I need to take plate resistance into account or something. I'm calculating the rolloff frequency when the capacitive reactance is equal to the plate resistor. So here goes ...
For a 100k resistor and a .01uF = 160Hz Yikes!
500pF = 3.2kHz Not horrible. That's a little more than 2 octave below where most people's hearing rolls off.
For some context, the fundamental frequency of the high e string on a guitar, at the 24th fret is E6. Roughly 1.3kHz.
The idea of placing capacitors in parallel with plate resistors seems like something worthy of having in one's bag of tricks when dealing with instabilities or harshness in high-gain amplifiers. A 100pF capacitor in parallel with a 100k resistor places the rolloff at 15.9kHz. Probably not gonna hear that if playing clean but might tame down some problems.
It depends on the tube, the Ra, Rk, Ck, and Rg. But in this Bassman the 10nf is -3dB down @500Hz. 500pF is more @6KHz.
I really enjoy watching your insights on these amps. What are your thoughts on the fender custom shop ToneMaster and Prosonic models from the 90’s? Had my eyes on them but wasn’t sure how well they are built.
See my stream this past Saturday for longer explanation of exactly that. But to sum up, Prosonic flawed but fixable, pretty much OK after that. Tone Master = hot garbage.
@@PsionicAudio I’ll check it out! Thanks for the feedback!!
Ugh, glad you pulled that cap out. What are the usual culprits for constant static sound when an amp has the volume cranked but nothing plugged into it? Is that just the nature of old amps from 1965? Mine is a Hammond reverb converted to a 5y3 rectified, 2, 7591 power tubes, 2, 12ax7 amp. It sounds so nice but makes some noise and is quite sensitive to external "stuff"
It could be a lot of things. Dirty sockets/contacts, iffy solder joints, noisy resistors or pots, DC leakage, it’s quite a list. I can’t say with your amp, sorry.
But old amps do not have to be noisy.
Hey Lyle. That’s a real stinker.
But I ❤ the electric tuba experience!
🤣🤣🤣
“The Electric Tuba Experience” is an album on my top 10 least favorite albums
I hear ETE is going to play Coachella next year
So I suppose you're going to change 82k to upper PI plate and reconnecting NFB with different components and values?
Well at least the NFB circuit and used NFB level will change quite a bit. Could you record the sound before and after the mod, would be interesting to hear?
BTW I have built several amps but never used negative feedback in output stage because I try to think positive. 😁
why would you put the 500 pf cap over the plate resistor if it sounded good without it
Stability at high gain.
Dude! I have a pile of cts 500k long shaft pots on my bench. They are all brand new. None of them work! They all offer little to no sound most of the way through their sweep, then goes to 100%. These were used as a volume control on a new guitar build.
You mean, "hidden problems"?
I meant synonyms.
Help On my third “New” Voxac15ch. First 2 man. 2021
Bad
Third amp came today man. 3-22 so my “new” amp is 1-1/2 years old this month. Have not opened. How does 1 get an amp man. 2023 Vox ac15ch
Is this normal Newbie
Hey, heard your voicemail. Amps don’t have expiration dates and I doubt the first two had any issue other than probably tubes that didn’t like the shipping experience.
But ask the store you bought it from.