6SN7 & 6V6 Push Pull - increase gain - diyAudio
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Old 25th February 2013, 11:03 AM   #1
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Default 6SN7 & 6V6 Push Pull - increase gain

Hi, this is my first post on DIYAUDIO. I recently purchased a 6V6 push pull power amplifier which has 6SN7 as the pre-stage. I would like to increase the gain but do not want to void the warranty. Does anyone know of tube substitutes that can increase the gain?

Thank you in advance for any assistance!
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Old 25th February 2013, 04:34 PM   #2
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ummmmm, why? What other changes are you intending to make at the same time? Or are you just looking for some turbocharge result from a plug-in substitution?

Your question has two problems - it assumes a recommendation can be made on information so limited that its impossible; and it is based on a belief that "stuff" can be swapped about to acheive significant results with no other considerations.

The short answer is "no". The long answer is "perhaps, depending on a load of other variables, not the least your ability to solder..."
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Old 25th February 2013, 04:39 PM   #3
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6SL7 would be the solution if the warranty problem could be ignored.
To use 6SL7 requires some component modifications, but without knowing your circuit I can not say more at the moment.
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Old 25th February 2013, 08:22 PM   #4
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I need more gain because I removed a preamp from the chain. I no longer use two sources, instead just a usb -> spdif converter (volume is controlled in the digital domain), but the output of my dac is not enough to drive the Push Pull power amp to sufficient volumes.

I don't have a copy of the circuit, but I can solder to the point of replacing resistors/capacitors, etc. What do we need to change to accommodate the 6SL7?

Last edited by laosei; 25th February 2013 at 08:36 PM.
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Old 25th February 2013, 08:35 PM   #5
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Put the preamp back in.
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Old 25th February 2013, 08:40 PM   #6
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...or don't change the tubes, but the gain resistors - depending on the topology, the push pull should just have a resistor on each channel that changes the gain

as to finding it without the circuit, you'll need someone smarter than me to assist...
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Old 25th February 2013, 09:11 PM   #7
JMFahey is offline JMFahey  Argentina
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Put the preamp back in. [2]
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Old 25th February 2013, 09:15 PM   #8
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Putting the preamp back in would certainly solve the gain issue, but it muddies the sound - it's so easy to tell that there's 'something' between the DAC and power amp.
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Old 25th February 2013, 09:34 PM   #9
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Get a better line stage/preamp and put it in.
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Old 25th February 2013, 09:41 PM   #10
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Ok sounds like the simplest plan. I think there definitely needs to be a gain stage between my dac and power amp. Is it wiser to build a gain stage that has no volume attenuation and control the volume in the digital domain? My DAC is non-oversampling and has two 10 ohm resistors at the output, hence the low level output - so presumably it is better for the DAC chip to have a constant load after these resistors rather than varying the load (which is what a preamp does)?
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