Do we need preamp valves?

[ourclarioncall]

Haven’t listened to this with headphones or through speakers but it seems like the combination of modelling and power amp valves can give quite a good tone

Do even need preamp valves ? is it the power amp valves that really make a valve amp a valve amp ?

On the flip side I remember plugging a pedal with a valve in it into a solid state amp and it sounded bad .

[ourclarioncall]

www.google.co.uk/amp/s/www.soundonsound.com/reviews/fender-super-champ-x2%3famp

[thetragichero]

if you want any sound whatsoever from a tube amp, i would highly suggest installing preamp tubes

[ourclarioncall]

Oct 18, 2020 15:09:07 GMT -5 thetragichero said:

if you want any sound whatsoever from a tube amp, i would highly suggest installing preamp tubes

Any sound? Or any Good quality sound?

“ Rated at 15W, the amp employs a pair of 6V6 power-amp valves — as seen in classic small Fender amps like the Deluxe, Deluxe Reverb and Princeton — as well as a 12AX7 valve acting as the phase splitter, preparing the preamp signal for the Class-AB valve power amp.”

[ashcatlt]

People hate to hear it, but distortion is for the most part just distortion. Doesn't matter if it's tube or solid state, preamp or power amp. The curves are very much similar and the sounds are actually all pretty nasty. What really matters is 1) How far past the limit you're trying to go, and B) The filtering that happens on either side of the non-linearity.

[sumgai]

Oct 18, 2020 15:16:30 GMT -5 ourclarioncall said:

Oct 18, 2020 15:09:07 GMT -5 thetragichero said:

if you want any sound whatsoever from a tube amp, i would highly suggest installing preamp tubes

Any sound? Or any Good quality sound?

“ Rated at 15W, the amp employs a pair of 6V6 power-amp valves — as seen in classic small Fender amps like the Deluxe, Deluxe Reverb and Princeton — as well as a 12AX7 valve acting as the phase splitter, preparing the preamp signal for the Class-AB valve power amp.”

Did you think that your quoted passage meant that there were no pre-amp tubes at all, installed into these Fender amps?  'trag is correct - without pre-amp tubes, per your Thread Title, then the total sound output will be zilch.  Finding a "power-amp only" setup is likely to be an exercise in frustration.  (Although, that's exactly what you get with a FX loop - the Return jack almost always feeds directly into the phase-inverter/driver section, and thence on to the power tubes.  That negates the absolute requirement for pre-amp tubes in that particular situation, providing that you're using some other means to get the signal from the guitar to the Return jack.)

HTH




sumgai

[ourclarioncall]

My initial thought was Traj meant no sound, as in, preamp valves are essential

So I posted the specs in the amp during my confusion as this amp has no preamp tubes and I read it has a “dsp digital preamp”. Then I thought well is fenders internal digital stuff In the amp just the same as using an external stomp box as a preamp , like a clean boost or compressor.

But then I noticed the 12ax7 being used as a phase splitter?? Now I know the 12ax7 is the common preamp valve found in most amps and that it’s two triodes in one.

So is this phase splitter/ 12ax7 acting as a preamp ? Or a part of the preamp stage ?

[ourclarioncall]

So can you you actually plug your guitar signal straight into the power amp stage via the effects loop ?

[ourclarioncall]

Oh , I think I get what Traj meant now

I “think” he was saying that if you pull the preamp tubes out of an amp (that actually has preamp tubes) then you won’t get any sound as the circuit will be open and The guitar signal won’t get through

I’m sure Traj will clarify at some point

[thetragichero]

i was mostly being tongue-in-cheek. as in another thread, one needn't even use a physical amp these days. impulse response and di boxes are the future/present. amps are mainly for us dinosaurs

[ourclarioncall]

[ourclarioncall]

Trying to understand the preamp stage in an amp

I understand that a typical 12ax7 has two triodes in one tube.

Do we actually need to use both of the triodes or can we just use one?

I’m already making an assumption that both triodes are used or are essential but maybe that’s not the case ?

[thetragichero]

what amp? it's all a design decision
it's nice to have an additional gain stage in, say, a single-ended champ is nice to drive the power tube and recover signal 'lost' in the tone control stage
you could get away with using one triode for a preamp and the other as a phase inverter in a push/pull amp and certainly get sound. would it be pleasant? maybe
there's a number of reasons to use both triodes. it's there, why not? also guitarists love distortion so.... why not?

[ourclarioncall]

Oct 20, 2020 2:53:03 GMT -5 thetragichero said:

what amp? it's all a design decision
it's nice to have an additional gain stage in, say, a single-ended champ is nice to drive the power tube and recover signal 'lost' in the tone control stage
you could get away with using one triode for a preamp and the other as a phase inverter in a push/pull amp and certainly get sound. would it be pleasant? maybe
there's a number of reasons to use both triodes. it's there, why not? also guitarists love distortion so.... why not?

Thanks

I think I assumed that a 12ax7 has two triodes in it because it’s essential that preamps have 2. (A bit like how the power section will have 2 for the push pull setup in a non single ended amp)

Maybe you can help me here

Are there any amps out there that use just one triode (or one triode in a 12ax7) in the preamp and leave the other one untouched ?

What do all your typical fender amps do here ?

So using a second triode just adds more gain ? So could you have 5 triodes in the preamp stage if you really wanted to ?

[newey]

Where I take lessons, my instructor uses one of those Super Champ 2s(not that he has a choice, it's what's in the practice room). I, on the other hand, get to plug into a nice old Yamaha 2X12 solid state amp. For my money, those old Yamaha SS amps are the best-sounding SS amps ever made.

The Super Champ 2 is OK, the onboard FX are decent, and they're a lot less expensive than an all-tube Fender. They still don't sound as good as tubes, at least to my ears. I always wince a bit when folks use entirely subjective terms to try to describe a sound, but when someone talks about the "warmth" of the sound from tube amps, well, I guess that's as good a word as any.

[ourclarioncall]

Oct 20, 2020 5:58:00 GMT -5 newey said:

Where I take lessons, my instructor uses one of those Super Champ 2s(not that he has a choice, it's what's in the practice room). I, on the other hand, get to plug into a nice old Yamaha 2X12 solid state amp. For my money, those old Yamaha SS amps are the best-sounding SS amps ever made.

Not one of these is it? I found this amp today at work. 

[thetragichero]

those old yamaha solid state amps are great. I've had a b100 on my reverb watchlist for awhile. nice little amp but i have no need for yet another

[newey]

Not exactly that model, but very similar to the picture.

[ourclarioncall]

Yeah, I think these can fetch about £400-£500 which I was really surprised about. 

unfortunately this one has something wrong with , it was years since I plugged into it, it just sits doing nothing . You jogged my memory when you mentioned ss Yamaha amps 

[reTrEaD]

Oct 20, 2020 3:03:30 GMT -5 ourclarioncall said:

Thanks

I think I assumed that a 12ax7 has two triodes in it because it’s essential that preamps have 2. (A bit like how the power section will have 2 for the push pull setup in a non single ended amp)

Your reasoning is inside-out and backwards on that.

The reason a 12ax7 has two triodes has nothing directly to do with guitar amplifiers. At the time these tubes were designed, vacuum tubes were used for nearly all consumer electronics.

Dual triodes and other tubes with more than one device in a package were desirable for cost and space saving. It didn't cost much more to manufacture a dual triode than a single triode. So the price point was considerably lower for a dual triode than for two single triodes. Plus a dual triode takes up half the physical space of two single triodes. Plus a dual triode generates less heat than two single triodes.

Oct 20, 2020 3:03:30 GMT -5 ourclarioncall said:

Are there any amps out there that use just one triode (or one triode in a 12ax7) in the preamp and leave the other one untouched ?

You'll be hard-pressed to find a guitar amp with just one triode in the preamp. If you do, it's likely to have no tone control (tone stack are lossy so with less gain available you'd want to dump the tone stack).

I seem to recall a very low power amp homebuild project that used just one 12ax7. Half of it was the preamp and the other half was a single-ended output stage. iirc it was around 1Watt. Kinda cute because it had a small footprint. But still, the transformers take up a lot of real estate .

Oct 20, 2020 3:03:30 GMT -5 ourclarioncall said:

What do all your typical fender amps do here ?

There is no such thing as a 'typical' Fender amp.

Oct 20, 2020 3:03:30 GMT -5 ourclarioncall said:

So using a second triode just adds more gain ? So could you have 5 triodes in the preamp stage if you really wanted to ?

There might be a boutique amp or two that uses 5 triodes but that's serious overkill.

Ken Fischer used three triodes in the pre-amp (not including the phase-inverter) on his Trainwreck Liverpool and Trainwreck Express amplifier and they had more gain than any sane person would ever need.

[thetragichero]

soldano slo used 5 preamp tubes of i remember correctly, so the overdrive channel probably had about that amount. only used 1uf cathode bypass caps because with that many gain stages it's real easy to get muddy mushy bass