the power tube driver work in an amplifier

[hopkinWFG]

guys ! have heard of the power tube driver which is mainly of 12au7 or 12at7 category...well i just get learny on it as it serves to dissipate signal voltages equally into power tubes ? which mainly works in more than two power tubes type amplifier which i think it mainly refers to 100watt amp that.consists of 4 el34... well i then searched manuals and some of design do have the tube driver after the PI tube.. but some dont... was wondering if thoese amps which lack of the tube driver would sound more unbalance ? so did any of the 50watt users?

 

[FourT6and2]

What?

The "power tube driver" tube is the Phase Inverter (PI). All Class A/B amps have one, regardless of wattage.

 

[hopkinWFG]

Mmmm ... am not too sure... but please allow me to take you an example for the old VHT classic pittbull 100 comes with 6 preamp tubes which consists of the PI at V5 and a non 12ax7 at V6 to be a 12au7 driver... and thru refinements the classic then evolves to be the CLX which excludes the 12au7 driver i supposed to be.. where UL uses 12at7... have no idea what it does in the circuit ... but after much read ups i supposed that i got my answer to be a signal driver for the power tubes... which has no significance on the gain factor that constitutes to gain level of the amp ?

but puzzled is why the clx didnt have the au7 anymore

 

[FourT6and2]

The tube you are talking about with the 100CL is a REVERB driver tube.

http://www.vhtusers.com/documents/G100CL_functions.pdf

Some other amps can use a 12AT7 as a Phase Inverter tube as well, and is generally interchangeable with the 12AX7 in that position. But there is no amp that I know of that has a Phase Inverter position and then another 12AX7 or 12AT7 or 12AU7 after it to additionally drive the power section. The Phase inverter's job is to split the drive signal and invert half of it to drive both halves of the power amp equally. And all Class AB amps have it. And the Phase Inverter most definitely has an affect on the sound of the amp.

"Driver" tubes generally power an effects loop or a reverb. And it seems you are confusing these tubes with the Phase Inverter as well as people reporting that they've substituted a 12AT7 for the 12AX7 normally found in the PI spot.

So to answer your original questions again:

guys ! have heard of the power tube driver which is mainly of 12au7 or 12at7 category...

Correct. In many amps, you can substitute the 12AX7 in the Phase Inverter spot with a 12AT7 and less commonly, a 12AU7.

well i just get learny on it as it serves to dissipate signal voltages equally into power tubes ?

Yes, sort of.

which mainly works in more than two power tubes type amplifier

Correct. Sort of. Most Class AB amps (push/pull design) where there are at least two power tubes.

which i think it mainly refers to 100watt amp that.consists of 4 el34...

No. Any Class AB amp. Including amps that have 2 power tubes, 4 power tubes, 6 power tubes, 8 power tubes... any power amp that has tubes operating in pairs. Doesn't matter if it's EL34, 6L6, KT88, 6550, etc.

well i then searched manuals and some of design do have the tube driver after the PI tube..

You misunderstood those manuals. They are referring to either Reverb or Loop driver stages and have nothing to do with the power amp nor driving it.

 

[FourT6and2]

I take that back actually: http://www.fryette.com/manuals/G100UL_SFD.pdf

I have no idea what the 12AT7 "Power Stage Buffer" tube does here.

And the old C-100-CR has this:

V1: 12AX7 -- Gain Stage 1 (1st Stage) both halves - All Channels.

V2: 12AX7 -- Gain Lead Channel (Stage 2 & 3) both halves - Lead Channel.

V3: 12AX7 -- 1/2 for Stage 4 for Lead Channel & 1/2 for Tone Control Driver.

V4: 12AX7 -- 1/2 for Stage 2 Rhythm Channel & 1/2 for Stage 2 Clean Channel.

V5: 12AX7 -- 1/2 for Reverb Recovery & 1/2 for Reverb Mix.

V6: 12AT7 -- Reverb Driver (Both halves)

V7: 12AX7 -- 1/2 Effects Return & 1/2 Phase Inverter

V8: 12AU7 -- Voltage Amp Power Tube Driver

This is the first I've seen of an amp using this type of topology. Best bet would be to contact Steve Fryette and ask him. The majority of other amps out there don't do this to my knowledge.

 

[GuitarGoat]

It's a buffer for the power tubes. I believe Ampegs used them too (SVT) and some Dumble Steel Strong Singers have them. Just allows for a cleaner output stage I believe. I've never used one but plan on it to see the difference in sound. Not sure specifically what it'd sound like.

 

[hopkinWFG]

I take that back actually: http://www.fryette.com/manuals/G100UL_SFD.pdf

I have no idea what the 12AT7 "Power Stage Buffer" tube does here.

And the old C-100-CR has this:

V1: 12AX7 -- Gain Stage 1 (1st Stage) both halves - All Channels.

V2: 12AX7 -- Gain Lead Channel (Stage 2 & 3) both halves - Lead Channel.

V3: 12AX7 -- 1/2 for Stage 4 for Lead Channel & 1/2 for Tone Control Driver.

V4: 12AX7 -- 1/2 for Stage 2 Rhythm Channel & 1/2 for Stage 2 Clean Channel.

V5: 12AX7 -- 1/2 for Reverb Recovery & 1/2 for Reverb Mix.

V6: 12AT7 -- Reverb Driver (Both halves)

V7: 12AX7 -- 1/2 Effects Return & 1/2 Phase Inverter

V8: 12AU7 -- Voltage Amp Power Tube Driver

This is the first I've seen of an amp using this type of topology. Best bet would be to contact Steve Fryette and ask him. The majority of other amps out there don't do this to my knowledge.

Thanks for the kind reply and help ! as said I have gotten a reply and think its sort of a post driver section for the AT7s and AU7s

http://www.fryette-users.com/forums/sho ... #post25520