TAD7025WA's vs. Genelex T12AX7:

Inspector #20

Inspector #20

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I'm running a Genelex Gold Lion T12AX7 in V1 and 7025-WA's in V2, V3, and V4.

I'm looking to reduce my overall gain, but I cannot see the T12AX7 as contributing that much to the ampunt of gain my DSL40C is producing.

Thoughts???
 
I'm not a expert on amp and amplifier circuit design to produce a certain amount of gain; be it more of the gain or be it less of the gain, or how you shape the actual tone to produce particular flavors of gain. It would seem to me that despite rolling tube types to add or subtract the amount of gain, the basic circuitry of an amp will not change drastically by using different tubes. A Fender amp will still have those Fender characteristics as does a VOX amp, and a Marshall circuit.

I maintain the exact tube types that were recommended by the manufacturer and work within that set of known tone factors. I don't really want to swap tubes to the point that I stand the risk of damage to the circuit months down the road from now.

Just my thoughts and am probably way off of 1st. base. Anyone want me caught off the bag and out?


Classicplayer
 
Stratstrangler said:
I'm not a expert on amp and amplifier circuit design to produce a certain amount of gain; be it more of the gain or be it less of the gain, or how you shape the actual tone to produce particular flavors of gain. It would seem to me that despite rolling tube types to add or subtract the amount of gain, the basic circuitry of an amp will not change drastically by using different tubes. A Fender amp will still have those Fender characteristics as does a VOX amp, and a Marshall circuit.

I maintain the exact tube types that were recommended by the manufacturer and work within that set of known tone factors. I don't really want to swap tubes to the point that I stand the risk of damage to the circuit months down the road from now.

Just my thoughts and am probably way off of 1st. base. Anyone want me caught off the bag and out?


Classicplayer
Click to expand...

You won't damage anything by changing tubes...so long as you perform the swap correctly.

And yes, they do "color" the amount of gain and to be to some degree, the tone as well.

12AX7 Comparison of Current Made Tubes | Amplified Parts
 
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No offense Robert the DSL amps every one I played stock at my local Music store clean channel was OK but the overdrive channel was harsh like running your fingernails across a chalk board.
I wanted to pull out the chassis and find out why no dice.
Back in the late 1970's Lee Ritenour was my guitar teacher Lee turned me on to many recording sessions I had only 3 guitar amps all were modified by Billy Zoom 1958 Fender Deluxe
1966 Fender Pro Reverb and a 1977 135 watt Fender Twin only part I know for sure was Billy used Amperex made in Holland tubes and next day service
I have sold the amps but have serviced them they look 100% stock
 
67plexi said:
No offense Robert the DSL amps every one I played stock at my local Music store clean channel was OK but the overdrive channel was harsh like running your fingernails across a chalk board.
I wanted to pull out the chassis and find out why no dice.
Back in the late 1970's Lee Ritenour was my guitar teacher Lee turned me on to many recording sessions I had only 3 guitar amps all were modified by Billy Zoom 1958 Fender Deluxe
1966 Fender Pro Reverb and a 1977 135 watt Fender Twin only part I know for sure was Billy used Amperex made in Holland tubes and next day service
I have sold the amps but have serviced them they look 100% stock
Click to expand...

Hey!!! I greatly value your opinion.

I agree, the overdrive is really heavy sounding to me...UNLESS I run it on the "green" (Classic) Channel...
 
67plexi said:
No offense Robert the DSL amps every one I played stock at my local Music store clean channel was OK but the overdrive channel was harsh like running your fingernails across a chalk board.
I wanted to pull out the chassis and find out why no dice.
Back in the late 1970's Lee Ritenour was my guitar teacher Lee turned me on to many recording sessions I had only 3 guitar amps all were modified by Billy Zoom 1958 Fender Deluxe
1966 Fender Pro Reverb and a 1977 135 watt Fender Twin only part I know for sure was Billy used Amperex made in Holland tubes and next day service
I have sold the amps but have serviced them they look 100% stock
Click to expand...

This guy gets decent tone on the green channel - the first test in the video:


So, I am looking for something between 'Green' & 'Red.'
 
Stratstrangler said:
Robert, is your DSL40 one of the brand new ones?


Classicplayer
Click to expand...

yes. I have 2 of them: a 2015 and a 2016. The 2016 is totally stock and only kept as a back-up. The 2015 has upgraded tubes and a 50 watt WGS Reaper 55Hz speaker...I down sized from my old SLP full stack in favor of something smaller...

WGS Reaper.jpg

Ignore the '30 WATT' decal - WGS doesn't have a 50 watt Reaper decal. It was a special order built by Trevor English.
 
Maybe try a 5751 in position 1. A 5751 is essentially a ruggedize 12AX7 (developed for avionics applications) that has an amplification factor of 70, as apposed to a 12AX7"s amplification factor of 100. So it has 70% the gain of a 12AX7. A NOS one would be your best bet, they are quite available. Hope this helps. Cheers
 
ivan H said:
Maybe try a 5751 in position 1. A 5751 is essentially a ruggedize 12AX7 (developed for avionic applications) that has an amplificaction factor of 70, as apposed to a 12AX7"s amplification factor of 100. So it has 70% the gain of a 12AX7. A NOS one would be your best bet, they are quite available. Hope this helps. Cheers
Click to expand...

I have several sets of Marshall branded tubes...
 
ivan H said:
Maybe try a 5751 in position 1. A 5751 is essentially a ruggedize 12AX7 (developed for avionics applications) that has an amplification factor of 70, as apposed to a 12AX7"s amplification factor of 100. So it has 70% the gain of a 12AX7. A NOS one would be your best bet, they are quite available. Hope this helps. Cheers
Click to expand...

I've used NOS 5751's (RCA's) to tame V1 in a couple of amps that were a bit too hot in the past. A very good way to go.
 
Robert Herndon said:
yes. I have 2 of them: a 2015 and a 2016. The 2016 is totally stock and only kept as a back-up. The 2015 has upgraded tubes and a 50 watt WGS Reaper 55Hz speaker...I down sized from my old SLP full stack in favor of something smaller...

View attachment 13726

Ignore the '30 WATT' decal - WGS doesn't have a 50 watt Reaper decal. It was a special order built by Trevor English.
Click to expand...

I think he might mean the updated ones that were just released at the last NAMM show (2018 update).

Marshall DSL40CR 40-watt 1x12" Tube Combo
 
gball said:
I've used NOS 5751's (RCA's) to tame V1 in a couple of amps that were a bit too hot in the past. A very good way to go.
Click to expand...
Yes, I've done the same. All the 12_ _7 series tubes have the same pinout, so with tubes being very "forgiving", a 12AU7, 12AT7 etc can be popped in where a 12AX7 is called for & still work. The thing is that the tubes supporting circuitry is not optimized for the substituted tube so it will not be working to its best. By using a 5751, the supporting circuitry IS to its exact requirements, so it performs exactly as a 12AX7 only with less gain. I'm not up on new production 5751 specs, but a NOS type was built to have very low noise & microphonics while operating in high vibration environments, & to last well in such applications. Gain was traded for low noise & microphonics. Cheers
 
ivan H said:
Yes, I've done the same. All the 12_ _7 series tubes have the same pinout, so with tubes being very "forgiving", a 12AU7, 12AT7 etc can be popped in where a 12AX7 is called for & still work. The thing is that the tubes supporting circuitry is not optimized for the substituted tube so it will not be working to its best. By using a 5751, the supporting circuitry IS to its exact requirements, so it performs exactly as a 12AX7 only with less gain. I'm not up on new production 5751 specs, but a NOS type was built to have very low noise & microphonics while operating in high vibration environments, & to last well in such applications. Gain was traded for low noise & microphonics. Cheers
Click to expand...

You are absolutly right about the supporting circuitry, I did not mention it because I felt in a guitar amp preamp stage it was not as big of a deal, as maybe to power stage.
 
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