Dr. Z AMA: "Voicing an amplifier"

[@shyammohabir8283]

I accidentally stumbled on this channel - wow what a find! As a armature tube amp enthusiasts I build my first amp in 1970's .. with ecc82/83 preamp/phase inverter tubes and push-pull with 6L6 pushing a 50-60W - 12" Goodman's speakers . The first time I hear sound off the speaker .. I felt like I was the King of the World! Thanks for your Channel it brings back tons of teenage years memories!

[@michaelknight4041]

I too remember the first time I achieved AMPLIFICATION! It was out of an old trashed out organ amplifier that I hacked into a sort of champ type thing. It was definitely a special moment when, after several tries that resulted in silence, I finally heard.....a sound! "It's Alive!!", I screamed!

[@geraldhinson]

As a hobby builder, easily one of my favorite of your videos!

[@WolfgangSambs]

You're awesome Dr. Z 🙂 Thank you!

[@PhotographybyCade]

Thanks for the reply

[@MattEdie]

Thanks for the forum plug Doc!

[@kentharding5874]

I recently got Bias amp, very cool. This video has given me the answers to what effect different parts and electrical values can do to effect the overall sound of an amp. Thanks man!

[@paulgamble6544]

Thanks for answering my question sir! Learning so much from you, the forum, and from these videos.

[@carvin69thinline65]

Awesome lesson Dr. Z. The enthusiasm in your voice makes all this technical stuff bearable.

[@santiagocolt2574]

you probably dont give a shit but does any of you know of a way to get back into an instagram account? I somehow forgot my account password. I would love any tips you can offer me!

[@santiagocolt2574]

@Terrence Tristan thanks so much for your reply. I got to the site through google and I'm waiting for the hacking stuff atm. Seems to take quite some time so I will reply here later when my account password hopefully is recovered.

[@santiagocolt2574]

@Terrence Tristan It worked and I now got access to my account again. I am so happy:D Thanks so much, you saved my account :D

[@terrencetristan5865]

@Santiago Colt Happy to help :)

[@jesseyasaitis9036]

Great video, I'll have to watch it a few times to soak it all up.

[@johnnytruck2009]

So much to learn. Thank you for sharing your knowledge.

[@SandersAmps]

Friggin fabulous lesson. Thank you!

[@stevenhaynes1031]

Z, these videos are fantastic. Thanks so much!

[@seamanjive]

Informative as ever doc, excellent analysis of the negative feedback loop config. BTW, my early Maz 18 NR head was killer at my gig tonight (as usual). First time gigging with the Brake Lite - it just works !

[@pierre-lucgirouard7967]

Thanks to share all that science with us

[@whimpypatrol5503]

The ears of the greatest studio producer and skills of the best amp tech, Dr. Z.

[@theguitaramptech]

Hey Mike, I am binging on your videos, which I have just discovered. Your videos are a great balance of education and promoting the attention to detail you have in your amps. I haven’t had the chance of getting one on my bench yet. They just don’t seem to break down here in Australia! I played one at Sunburst Music (for whom I do amp repairs) that has one on the floor, which is simply gorgeous. I can’t wait for you to have a failure in Australia so I can drool over the insides. 

[@DrZAmplification]

Let's not wish that on anyone!

[@DrZAmplification]

Dry Aussie heat, makes for a long long lasting amp!

[@theguitaramptech]

Dr Z Amplification, HA! Good for Dr Z amps...bad for my repair business 😂

[@Okla_Soft]

Wow, that was super-informative Dr.! Thanks!

[@Jakexx01]

Thanks for that wellspring of knowledge. I'm new to your products, but do have my eyes on either the Remedy or the Maz 38 NR. Two distinctly different beasts to be sure. But such beautiful beasts! I would love to someday make a wet/dry rig with either one of them for the grind along my 1961 Fender Showman for the modulation/spatial effects. It would sound like entering Valhalla in a hurricane from the back of an eagle!

[@DrZAmplification]

You have good taste!

[@fpapaleo74]

Doc. you are the best! My next amp will be a Z for sure! Cheers

[@williamwagnon2809]

Thanks for your info. Good basic info.

[@CountryHitsUSA]

Great info! Thanks !

[@jacobalvarez7515]

Man the Dr. is a genius

[@petegaslondon]

Oh, interesting! 1:11 .. I'm into the tradeoff btwn using a big transformer (I play bass thru my tube amps!) vs having an undersized tfr and letting it suffer and saturate a bit (which sounded .. interesting on my Mk 001) - lets see if you cover that ? 2:14 some people use 'voicing' to mostly mean the EQ tweaks that happen on the way, but you're including the output section? this should be interesting.. 3:33 just to be awkward people HAVE gotten away with EL84 at crazy plate voltages long as you keep the screens within rating (my 001 amp was like that, even more so when I changed the rectifiers to silicon! The tough Russian EL84s took it fine but I cant speak for todays tubes!) 5:16 Ahh you've no doubt noticed Marshall tend toward a LOWER than rated a-a transformer impedance - I sure wish I could afford a PILE of different iron to experiment :) 8:14 Ahh I never noticed that! Blackface's have way more NFB - never got to play with them much, the main difference i saw was smaller coupling C's - I suspect due to the same problems I get when letting the low end go through - MASSIVE HT line variation, subsonic wobbles! Oh and I HAD a real AC30 for a while - yeah WAY loud - like my 001 build, EL84s lots of gain, hot bias (sigh) it was niiiice Since the eviction I've had to kerrang thru silicon lately which isnt TOO bad but .. I kinda got something new in the works - Rock On!

[@mercatorjubio3804]

This is pure gold!

[@Schlumbucketreturns]

Good job, Mr Z.

[@pedrolourenco2707]

Was expecting much more from this video! From my experience a lot of magic happens in the way preamp stages are biased and bypassed (plate and cathodes) in conjuction with coupling caps...

[@sthengr]

Great video, lots of information, thanks!

[@horusjones5213]

Dr z needs more views

[@KleyDeJong]

Great stuff Z. Do you ever use the components that interact with the plate or cathode of a 12AX7 to voice the amp as well?

[@DrZAmplification]

Kley De Jong sure do! That’s more front end gain staging than “voicing” per-say. But a bypass cap here or there, or a different bias resistor will definitely effect the frequency response. That would come during the fine tuning stage.

[@RulgertGhostalker]

i sort of had a sound in my head i was going for with my EPS Tube Stack...but the absence of negative feedback really shaped the design ... i like the AC-30, ( though i wanted a little more transient compression than a GZ-34 type ) but there is something really raw and bitchy about less negative feedback that i like, but that can be very difficult with tolerances too, and how do you keep it tight?... so it sort of pushed me into the full grid go.. i have been studying tube amps on and off for decades, crazy the Proto would be my first build......if i ever get it built... i am so simultaneously poor, and busy, that i can hardly function.

[@RulgertGhostalker]

i have to do EPS like an open company at this point, i just don't have the time and resources.. haveing no electrical engineering certification, i think the company would do better if i had an "engineered by Dr. Z amplification endorsement for a 5% in on it or something... i don't know if EPS is ever going to get off the ground... i think it's going to come down to how many people feel the need for another guitar amp company ..

[@RulgertGhostalker]

i mean i can get the engineering, it is just going to take me a little longer than it would you... the real problem is i have No Floor Space, and No Spare Dough.......that and i am hiding out from these african heroin dealing freaks, because i have done under cover work, and it still not stopping the crap, and the police can't protect anyone until after they are dead.... where is our military when we need them here ? america is being conquered by african heroin, and the united states government is literally starting all these other problems in the world because they make money doing it..

[@RulgertGhostalker]

i finished my science work ( on my FB timeline ), and i have to finish my motorbike build now... i should be back on the EPS amp design by winter....i already talked to Weber Speakers about it, i am thinking the heads would get shipped in the cabinets and i would forward the address with payment to Weber, and they would just ship like they do.... i don't know how this is going to go yet, i might be the one with the 5% ( in licencing fees ) .... i just want to make sure the junk doesn't get into the op .... the ____ have been targeting company heirs, and taking over businesses, and using them to launder heroin money ...i have every legal right to refuse employment of ____ for their affiliation with african heroin ... the problem with the ______ is the way they use everything as a weapon ... so be careful, don't talk to____ about problems with _____, and know who your friends are. i can be contacted if there is any interest.

[@RulgertGhostalker]

i am the EPS design project coordinator ... that is the minimum involvement i want to hang onto, beyond the initial rough out ... i will put a "Dr.Z engineering" logo on the chassis, if you want in on it ... otherwise i will get back to the model this winter.

[@RulgertGhostalker]

i want the EPS Tube Head over engineered because EPS would be able to afford too, ( low parts count ) like really smooth supply filters, metal top PNPs and generous component ratings, quality signal chain caps ... and it will still be a tube amp ... some people will buy it, just because it ends up being the amp they decide they want ... or the next amp they want, or a second or third amp they want....it will fit in somewhere. the power filter torroid inductors just hang on the bottom of the can cap solder lugs.( zip tied together ) i am thinking two small circuit boards, 1) the single phase voltage patch + filament supply, on spacer transformer bolts under the PT 2 ) the -Vbias circuitry cantilevered on spacer transformer screws under the OT ( no trimmers, 5 actual pots with micro knobs ) some on the tube sockets and panel components, with any otherwise lose stuff on terminal strips...

[@L.Scott_Music]

I wonder what would happen if you distorted or compressed the negative feedback. ??

[@TomiKettunen]

Do you ever start the design process by first choosing the speaker for the amp or is it the some of the last things you would do? Thanks for doing the the video!

[@DrZAmplification]

Not usually, though some times it does necessitate picking the speaker first. For example, designing the Z Master, we knew we had to make a 3x10 configuration and we knew we wanted a specific style of vintage alnico speakers to be spec'ed out. In most cases, the amp is designed first, then the speaker is shot out with a slew of options, then a lot of tweaking and revisions can be done after that.

[@TomiKettunen]

@@DrZAmplification How about choosing a spesific type of guitar first and then designing the amp voicing and other characteristics after that for that? For example a single-coil equipped telecaster favours a different amount of bass and overdrive compared to a humbucker and es-175 type of guitar. Thanks for your reply 👍

[@fuzzprobe]

Nice video! Thanks!

[@Kyle-kr4hl]

Hey Mr Z. At the begging you talk about British and American voice being relegated to el34 and 84 or 6l6 and v6. Would the 5881 fall under American and the kt 66,77,88 under British? I have noticed that you have a kt series. Thanks for these wonderful videos!!

[@DrZAmplification]

It's a very general assignment as the tubes themselves originated in America (6L6, 6V6) and then Britain (KTs, EL84, EL34), but a 5881 could go either way. A 5881 originated as a ruggedized version of the 6L6, but before the KT66, the 5881 was used in the earliest JTM 45s. Tubes themselves are more applicable to how and what circuit they are used in, these are just general descriptions of how and where they have been used in circuits in the past.

[@praneethdhanushka207]

Dear sir, you are great in explanation!!!! I need to know that I have a ground loop (Hum) of my guitar amplifier when infixed to the electric guitar. To eliminate the noise, is it possible to setup DI box in between Amp and guitar??? Thanks

[@PhotographybyCade]

Hello I have the Carmen Ghia combo amp, what tubes do you recommend . Playing clean and the blues.

[@DrZAmplification]

5751 for the two 12ax7 slots, 6n14n power tubes. That will increase the clean headroom

[@johnnylance]

Question: What are some mistakes people make when trying to get good sounding distortion/overdrive out of multiple cascaded gain stages?

[@hosoiarchives4858]

I like Dr Z

[@armchairdisaster905]

What about amps with kt88 or kt66 tubes ,they are your best sounding amps ?

[@DrZAmplification]

Great tubes. Some of our favorite tones.

[@evanmiller2579]

Great stuff as always. Would love a video on pairing amps together much like Brad does. Would it be best to pair an American voiced Z with a British voiced Z or are there others factors that are just as important? #drzama

[@shanegreen9376]

Why do we rarely see say a vox preamp with 6v6's etc?

[@DrZAmplification]

Great question. I'm not particularly sure why that hasn't been a thing yet, but understand that 6V6 tubes were not readily available when the original voxes were made in England.

[@michel333100]

Hi Mike, I'm sorry to bother you with another question about my Mesa Boogie Tremoverb amp combo. In regards to using 2 -GZ34 rectifier valves. I went ahead and tried these in my amp. It worked ok until I shut off my amp without putting it in standby first and it blew a fuse. My amp was doing this before when I used these same rectifier valves. I had sent this all the way back from Canada to California for repairs. Is it because I am using these rectifier that it is blowing fuses when you shut the amp off like this without putting it in standby first ? My other amps do not do this when I just shut them off by switching the power directly off. Can you give some advice as to why this is the case with the Tremoverb? Thanks from Michael Newell from Niagara Falls, Ontario, Canada

[@DrZAmplification]

From what it sounds like, one of the rectifier tubes is bad and arcing, causing the fuse to blow. Replace the fuse and remove the rectifier tubes and if the fuse blows again, something is wrong with the amp. If it doesn't blow, there is likely a bad tube.

[@ALEXONLIFE]

Dr Z, I have a tweed Harvard clone 5F10 I think. I am having the hardest time figuring out which coupling cap to increase the value of. This thing is way too bright with no bottom end and I would like to make it less shrill. Please tell me which cap to change. Mine has a 12AX7 as V1, Not the 6AT6 as the original schematic. I bought the amp from someone online years ago. Its so bright I cannot play it.

[@DrZAmplification]

It's impossible to know the actual issue that is causing this symptom as I can't tell you how or with what materials or if the amp was properly built, if it's a clone. But you should start with wiring the preamp tube socket for the intended preamp tube that the amp was designed around and sourcing the right tube, as this is essential to the gain structure. Changing a coupling cap will do nothing to increase the bandwidth of the amp if the preamp isn't providing the proper gain structure to reproduce the input signal. Caps do not increase the available gain.

[@ALEXONLIFE]

@@DrZAmplification I really appreciate the reply. However, this makes things more complicated and I was hoping it would be simple. My clone looks similar to the Fender tweed 5F10 but the first tube is a 12AX7 and so is the second. I only have two input jacks instead of three. I believe this was a kit that some supplier sold about 10 years ago but I do not know who. The amp works perfectly otherwise. Tone is good but still way to trebly. A Strat destroys my ears. I changed the first two coupling caps from .022 to .1 µF. So now it has four .1 µF in row. It got a little warmer I think but not much. What you suggest, to check if it was built correctly, is beyond my electronics knowledge unfortunately. The tube chart calls for the 12AX7 for V1. Should I try to find a 6AT6 maybe? Would it fit? I am ready to give up on this thing. Whoever made it did a very professional job inside. I wonder if I should just change the V1 for another tube, preferably the 6AT6, if still available?

[@DrZAmplification]

@@ALEXONLIFE .1uF is a common coupling cap used in early fenders. However it will not reduce treble, only allow more bass to come through. You can't put at 6AT6 in place, they do not have the same amount of pins. It would require a different socket and socket wiring. If you are not confident in your wiring, I would suggest trying a different speaker, something with a larger dustcap, perhaps an alnico magnet as well.

[@ALEXONLIFE]

@@DrZAmplification This Harvard clone has the Jensen P10R, which I understand is a bright speaker. Just as you say. I kept increasing the value of the V1P7 cap, which goes to the input of the volume pot. I noticed that there is no change in the highs but the bass slowly increases as the cap value is increased. I am now using a .22 (stock it is .022) in that position and it is a lot better, more balanced as the bass was increased. Its not quite there where I would like it, so I ordered some .33 and .47 caps and that may just do it. It will still be a bright amp but at least it will be balanced with the lows. I am using a 12at7 in both the V1 and V2 positions. Is this the best way to achieve what I want or is there a trick to cut only the highs?

[@DrZAmplification]

@@ALEXONLIFE a 6AT6 is closer to a 12ax7 in gain structure, and the phase inverter calls for a 12ax7 so I'm not sure why you have 12 AT7s in those positions. a 12 AT7 will lower the gain, reduce the midrange, and accentuate the high end.

[@aussie_philosopher8079]

Why the bloody hell didn't anyone on gear page tell me about dr.z videos

[@StratmanJerry]

This is all very interesting thinking from an audiophile hifi point of view

[@thierrycaudron3266]

Hy is it possible to change inside componnents to transforme bass ampli guitare to normal ampli .I se you in yutube from France and I çan understand bécasse you speaker son slowly and clearly thanks

[@DrZAmplification]

Depends on how modern of a bass amp. The difference between a Marshall Super Bass and a Super Lead amplifier is about 4 components and a slight wiring change.

[@geezberry8889]

i guess the CAZ-45 is for me

[@terrybanks5063]

cheers for sharing! i wish i was in the usa, i would ask if i could be an apprentice and id happily work for free! its my dream job..oh well im sure youre not short of offers anyway!

[@gabet3754]

I worked as a mechanic for 11 years and we call transmissions “tranny’s” too

[@thomkopal1740]

So it’s basically a simple choice between a British amp, such as Selmer… and an American amp, such as Ampeg? Valco? Magnatone? Gotcha!

[@moses1202]

I just replaced el84 in my ac4c1 by 6v6 today. It sounds American 🇺🇸😂