"The most UNQIUE amp I've ever made?" (Z-80 technical deep dive)
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- Опубліковано 7 лют 2025
- Dr. Z goes in depth on his latest amplifier, the Dr. Z-80. Come explore the inner workings of this unique design that was 6+ years in the making.
www.drzamps.com/product/z-80
I was lucky enough to have played through a prototype of this very amp at Maple Heights a few years ago. I can tell you this. It’s as much and more as what he says. The harmonics jump out of it and talk back to your fingers instantly if you wish and that 3D Dr Z sound hits you like a tsunami of angels. It’s truly a benchmark in amp design history.
The gut shot from a Dr Z amp is a work of art.
Sun God Kukulcan like your comment he say 👶🍼🎧🙏
I spent 41 years repairing amps for a music store. I am retired now. I can say this is a nicely made amp and one I would not mind working on if I were still servicing electronics. The individual cathode resistors are nothing new but they are not commonly seen in today's amps. I also like the way Dr Z makes his videos and the way he explains everything.
Man the experience and knowledge of electronics you must have is super impressive. What are some of your favorite guitar and bass amplifiers?
Seriously though respect to Dr. Z for showcasing his own machine for us like this. Awesome
As an owner of a Z-80 head, I can't stress strongly enough, how wonderful this amp is. It really is like nothing else you've ever experienced. Guaranteed to put a smile on your face, every time you plug in. It's the type of amp that just makes you want to keep playing.
Isn't EL34 supposed to be like a marshall?
I just purchased this amp with the matching 212 bottom two weeks ago from Sweetwater. It is the best amp I’ve ever played through. Thank you, Dr. Z.
Great to hear!
Another great product Z. Your amps are worth every penny. I only wish I had that many pennies....
Doc, you are a national treasure. Love my Z amps and love hearing you explain your amps!
One thing that Dr z does so well is add a mid control without destroying the tone stack of the Ac style amps. A lot of that top boost sound is the tone stack and so many people 'fix' it and then it loses the actual top boost sound especially when people just change the tone stack for a classic bassman style which shifts the mids so much compared to the TVB tonestack. Every clip I've heard of that amps sounds like the big boy voxs to me with that added Dr z grunt and punch, really would love to play one in person.
This is a really great explanation. Thanks.
That Dr Z amp looks amazing.
Just when I think I’m out of the new amp game, you pull me back in. This is honestly the most exciting amplifier I’ve seen in a long time. The few clips I’ve found online sound gorgeous.
Sorry and thank you? 😂
Beautiful chassis layout. Clean, orderly, elegant. 👍👍
The good Dr is amazing. I have a Z wreck jr that is incredible and will become an heirloom . I have no need or means to get a Z80, but boy howdy I would LOVE to have one.🤟🤟
Nice video and great re-design of this this Vox model.But you didn't mention the power capaciters (the blue tubes on the outside).
Questions from my side: is it possible to install a pre and post phase inverter mastervolume?So you can also use the phase invertertube for more soundsculpture. Second question: speakerdamping variation or Focus control,can you add this ,to this model?I have different Rivera amps with Focus control,which is to me,a very nice option,to adjust "the feel" of a tube amp.From a stiff to a loose feel of your amp,just the amount you like or wish.
@@jochemjonker3362 1. it is possible, but there would be no use to this as the amp doesn't generate any overdrive pre-phase inverter. 2. the focus/speaker dampening control is related to negative feedback. this amp, as all vintage vox circuits, does not employ and negative feedback. To do so would neuter the sound and intention of this amp.
Dr Z you have done it again , what an excellent build . I must say after playing more amps than digits on my body .That you build some tuff amps. Seen a guy in a bar drop his on some steps , plugged her in ,worked fine for the gig . Last I heard its still pumping . Nice layout on your boards too. Easy to service . That's what I like . Keep up the great work man. Peace ✌😎
I played a Z-Wreck at the CME last summer. It sounded so good that I didn't want to stop playing it. Respect.
Great video Dr Z!
I've never heard this amp yet I feel I must have one. I love my AC30, I love my '67 Twin. I think my 4x12 Greenback Marshall bottom will love this.
I think it most certainly will. Brad's vintage AC80 was pumped through a greenback 4x12 before he got the Z-80.
Now just waiting for a Z-40!!
I have built amps with that same idea, i.e. output tubes don't share the cathode resistor and bypass cap. The main reason in my case for that has been the fact that bias currents of those output tubes don't go easily out of balance even if the tubes are not perfectly matched because the idea of "automatic bias" works for every tube independently and you can adjust bias to quite hot more safely. Disadvantage is the need of quite a large bypass caps.
And the idea of using several smaller turret/eyelet boards is very good as well because it makes repairing much easier if necessary.
One thing you got wrong (the HORROR!) - for those of us who have to schlep our own gear: Why must the handle always be located dead center? Why can't the handle be located at (more or less) the center of gravity? Most of the weight is mainly on the PT side of the amp. Why not relocate the handle more towards that heavy transformer. Carrying a heavy, off-balance head is rough on our so very precious hands, dontcha know. Beautiful amp, though. No flies on that booger.
You crazy genius. Love you Dr. Z.
Awesome! Thanks Doc!
This is a neat product. Hope to hear the Dr. back on Tone Talk again in '24 to discuss it and all things tone relevant
we would love to talk with Marc and Dave again
Can't wait to try it.
The hoboroadie is usually unencumbered with surplus cash but fortunately you have released this at a rare moment when it may work out for us... anyway thanks- it is exactly the one that I wanted.
Great video. Thanks
Fantastic
Best thing about being Dr.Z? You’ve got every Dr.Z amp.
Great, as an old amp builder, i really appreciate your work. Analogue Modeling🤣
Little too much amp for me but I love my JAZ and it gets lots of love!
OMG Z. That power transformer and choke are huge! At the end of the day great tone=Kg of Iron.
looks real nice
Plate resistors! I thought you misspoke and meant screen resistors. But after a closer look, nope, you didn’t misspeak. What are the plate resistors on the El34’s doing? Oscillation stoppers? Lowering voltage to the plate? You don’t see plate resistors on power tubes often. Cool amp, btw!
Great question, something we will address on a follow up video.
My thoughts were was same as yours. I thought they were screen resistors. Since they are on the plates he is probably using them as output balancing resistors.
nice work & presentation, could you elaborate just a bit more about the "bootstrapping" on the 2nd preamp tube? thanks!
Reminds me of the story of the 30 watt EL34 1961 Fender tremolux 6G9, except in a 80 watt configuration.
I’m saving for either a MAZZ 18 mk 2 or z wreck head. Still on the fence on which 🤷♂️ hopefully by the end of 2024
Thats the floating paraphase inverter right? I really love the sound of that circuit in the Ampeg V4. This amp looks really interesting. I enjoy hearing you talk about amp design.
awesome 🎉🎉🎉🎉🎉 amp
I'm debating on getting a Z80 or Z Wreck both sound so good. Is it possible to get different color tolex other than black?
Thanks for considering us! Email us at media@drzamps.com and we can talk options.
@@DrZAmplification Perfect email sent
Vox trolly , so thts what they call it . Good to know . Thx Doc .
Output plate resistors is definitely different. Just tell me one thing, are you finally using star washers on the pots/jacks?
In manufacturing and engineering everything is a balancing act of trade offs. Cost/benefit, pro/con, call it whatever you please. We are at the mercy of our component suppliers, and pots are one of those components. The fact is certain values of pots we use are made with shorter shafts than others. Thus, the trade off between star washer vs flat is this: using a .090 thickness aluminum chassis, the pot shaft will only clear so far through the hole. Adding a star washer will prevent the nut side of the pot from gripping more than about a half a turn on the thread. A flat washer will allow for a few turns. So the trade off is a thicker chassis which will not bend or become malformed over time due to negligent handling, rough shipping, or the weight of the robust transformers we use vs the occasional loose pot that can be easily remedied by a twist of a socket wrench. Easy maintenance that all guitar players who can change strings or tighten a jack on their guitar can and should do (we made a video on it). If you are still concerned about the impending rash of future failures due to the lack of star washers on certain pots, please call Don at our repair dept. and he can pull our records of these occurrences to assuage your fears.
These are the things you discover building tens of thousands of amps by hand and being in business for 35 years. Not by listening to the regurgitated complaints of a handful of parrots who haven’t had experience with the former and spend more time behind a keyboard than at a bench. Thankfully, a strong business tract has allowed us to have the resources to employ people to spend copious time behind both.
That said, we have invested in equipment that will soon allow us to cut a countersink in our face panels which allow for the use of star washers on certain pots. A significant investment in equipment to quell the yammering of a scant few who must assume we will surely go under soon since we haven’t used a 3 cent part in our builds.
@@DrZAmplification I wasn’t really expecting a response, thank you. I don’t wan’t you to go under, I want everyone to do better and continue succeeding.
@@matthewf1979 I know you weren't, and I know you do, but the point of the response is there are many, many things to consider to keep 50s technology going in 2024.
Z amps are best! I bought 3 of them from his pawn shop when he played in The Crow movie 😂 \m/.
Like I really need an 80 watt VOX amp to blast out my neighbors. I bought an 80 watt version of a 25 watt Standel 25L15 amp made famous in the 1950's and 60's by Chet Atkins, Wes Montgomery, Joe Maphis, and others. But the 80 watt sounds nothing like the 25, at least not with PAFs which kick out heavy mid tones. It is way too big of an amp for me. I keep the volume knob at 1 or less when I use it. It has no gain or tone when I crank it, and i think it would make a better bass than guitar amp. Its hard for me to use 80 watts of ultra clean bass and low mid tones, even for jazz archtops, which was my thought when I bought it. The early low watt VOX amps for Gretches were heavenly, but Im not sure if they would be as beautiful for hollowbody and semihollows with PAFs. Since VOX didnt export their original tube amps to the US when American rockers were still playing Gibson hollowbodies and semihollows, i don't know of anyone who used them for such. As much as I like the tube tones of yesteryears, I just can't do the math of buying them one-by-one trying to match one for my playing style and needs. Maybe their will be hope in the future with digital and analog emulation of tube amps. But, what do you think; would an 80 watt VOX work to get loud, jazzy tones with PAFs without sounding mid tone ear piercing and treble ice picky?
Killer man.
what happened to the small amp movement ? that has to be one of the biggest power transformers i've ever seen in a amplifier , already on back order so first batch is gone ...
Am I wrong in saying that this would be a good bass amplifier? Or do you make another amp that would be suitable for a bass rig?
You aren't entirely wrong! It was originally voiced for bass. The first circuit contained an unruly amount of bass! now the circuit has been voiced a bit more towards the guitar range, but it still retains a lot of low end.
@@DrZAmplification thanks Doc 🙌🏻👍🏻
Nobody designs tube amps for hollowbodies (or even semihollows) with PAFs anymore, not since Leo Fender in the 1960's.
vishay sprague capacitors👍🏻
Dr. Z, is the Vox/Dumble-looking amp with the diamond grill cloth the exact same specs as the Z-80? I believe you said that is your personal Z-80?
Yes it is, early proto-type but same spec's. Just packaged differantly to my taste.
DR Z, How does Cathode Biasing be able to NOT Run DC biasing voltage through the PMVPI Post Master Volume Phase Inverter? FIXED Biasing has a negative DC biasing voltage on the grids of the power tubes, How and why would the negative DC bias voltage run through the PMVPI post master volume phase inverter? I would think the DC Blocking capacitors would block the negative DC biasing voltage to backfeed into the Post master volume phase inverter stage
Wayne I'm not trying to be snarky in any way with my response. But you should research how Cathode Bias circuits work in both Output tubes as well as pre-amp tube circuits. If you do you will realize the cathode resister generates the Bias voltage and applies it directly to the tube's Cathode not the Grid as in fixed bias , so a Cathode Biased PPIMV it does not have the DC Bias voltage applied to it only the Grid AC signal.
Combo Maybe Doc?
Good question John, but you do understand this is a near 100 watt amp right . Also not many if at all 1 X 12 configurations will do this huge sounding amp justice . So a 2X12 combo would sound best . A large 2x12 combo along with the Z 80 chassis will weigh in over 75 lbs. not a very friendly size and weight to gig with IMHO.
Z
@@mikezaite1335 Yep good call that makes perfect sense Doc.
I think the only person who could lug it around is the bionic man Steve Austin.
Congrats on another amazing amp.
You are on quite a roll
Why has no one reissued a JMI era AC50?? I would imagine they'd sell extremely well if they were redesigned with these exact modern additions.
... gooooooddd question...
I've got a 1964 AC50 that's relatively similar (I think)
Is this a Class A or Class AB design? Class A circuits don't use phase inverter? Those EL34s don't run in pairs? I have amp called Victoria Regal has independent filaments for 2 tubes, it's class A without PI circuit. Anyhow yours is very impressive, love to hear one. Cheers
The amp is class AB. The EL34s do run in pairs.
Since the tube are individually cathode biased, does that mean you could potentially swap them with any other power tube that have the same pin setup?
no! don't do that! There are voltage and current specifications that certain tubes will not meet. Great question though, we will do a follow up AMA on this.
Hello Z,
Quick question, I'm wanting to run my head with a 1x12 when doing smaller gigs, rather than using its matching cab.
Would the voicing of this amp work with a 90w Celestion Cream? It's essentially a 90w version of a gold right?
Thanks
The Cream has it's own voice. It's warmer and smoother than gold, with more low mids. Many people really love this alnico. We find it to be hit or miss, but it should work just fine with the Z-80. Another speaker that we have found work extremely well and I would recommend before the alnico Cream would be the 150w Celestion Redback. Excellent sounding speaker with the Z-80.
I noticed that the schematic shows 270Ω but the photos show 450Ω resistors for the cathodes. Why?
False flag? Boogie do it all the time to thwart plagiarism.
part of improvements on the original design related to reliability, good question, we will address in more technical detail in a following video.
@@MS-Patriot2 we aren't that secretive, just open one of our amps and someone can pretty quickly trace the big honking parts on there.
Wasn’t that a microprocessor from the 80s?
Can I come make amps with you?
Announcing my presence! I am a rich noob who just wants to figure out how this thing is "voxy" with el34!! I am laughing at myself as i muster the audacity to post such a noobish question to a genius like dr.z.
Some facts about me:
- i am a noob
- i am an electrical engineer
- i love vox but hate marshall
It's because the Vox sound isn't EL84s! It's their tone stack and lack of negative feedback. The main thing about EL84s is they compress and overdrive sooner than EL34s (and most power tubes). It's less about sound and more about the feel of the tubes. The sound, tone, and chime of "vox" is more about the circuitry.
In the same way, the kerrang and upper mid cut of a Marshall isn't about the EL34s (though those can accentuate it), but how they taper the low end early in the circuit and how the cathode follower circuit works. As well as the fact that Marshalls are fixed bias with negative feedback, and Voxes are cathode biased without negative feedback.
@@DrZAmplification thank you, screenshotted your comment and kept it for reference!!
As a technician who has been building Tube amps since the early 90's your work is very nice to look at but hardly amazing .
Wow, thanks! It’s a good think we don’t hear with our eyes!
What does that even mean? I too have been working on amps for a long time, and Z Amps are extremely well made and sound incredible.
@@tomolewine5743 well it means yes this build is a bit different with individual cathode biasing and it's a copy of an old Vox design using decent quality components which is nice. This doesn't make it amazing or unique. If it used an output transformerless design or circlatron or even a build using Transmitter tubes then that would be interesting. This is a nice well made amp and no doubt it sounds great but it's not doing anything amazing. So hopefully you get my point of view which I'm entitled to as are you.
breathing sounds are too loud
we don't have a standard set up for filming due to space constraints so the set up is going to be a little different every time, the mic might have been a little too close for the compression settings we used, we will be mindful of this next time.