I guess I found the answer to my own question by Fernando's post in here:
http://www.marshallforum.com/threads/new-dsl20hr-and-a-problem.100349/
http://www.marshallforum.com/threads/new-dsl20hr-and-a-problem.100349/
Dsl20 Gut Shots Before & After Marshall Update
- Thread starter Deerhunter1972
- Start date
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Just that, I'm sorry I'm late....
Well, I update you, as you know my amplifier had the problem of the small hisss (rest all OK), i was not upset with it and at first I was not going to do anything, but one day I was introduced to an amplifier technician and I told him about and he said bring me the amplifier and we see it.
Total that takes it and we talk about the R56 and R70 and before and after sending it to Marshall and the forum photos, etc.
Then we have exchanged these emails.
Hi Armando,
I'm looking at your amp and it's already "corrected". Even so I will replace the resistances with others of the same value but with another material, to see if it improves. It is true that it makes a lot of noise.
I update you, I have seen that the ampli is very noisy, not only the stage of the previous, also the power.
By changing the resistors and the capacitor I understand that it is sought to reduce the bandwidth of the previous one and reduce the noise somewhat. I have not gotten the value of the capacitor so I have not been able to continue there. The resistances that your ampli mounted are 1Meg, while those that appear in the photo that you sent me are 10Meg, so I think they have already modified that part.
I have tried with another inverter valve in the power stage, I have set an ECC81 and the noise in 3dB is reduced, losing only 1.5dB of global gain but respecting the gain of the previous one. The problem is that trying on the "ear" does not sound good at all.
Conclusion:
I leave it as it was.
Well, I update you, as you know my amplifier had the problem of the small hisss (rest all OK), i was not upset with it and at first I was not going to do anything, but one day I was introduced to an amplifier technician and I told him about and he said bring me the amplifier and we see it.
Total that takes it and we talk about the R56 and R70 and before and after sending it to Marshall and the forum photos, etc.
Then we have exchanged these emails.
Hi Armando,
I'm looking at your amp and it's already "corrected". Even so I will replace the resistances with others of the same value but with another material, to see if it improves. It is true that it makes a lot of noise.
I update you, I have seen that the ampli is very noisy, not only the stage of the previous, also the power.
By changing the resistors and the capacitor I understand that it is sought to reduce the bandwidth of the previous one and reduce the noise somewhat. I have not gotten the value of the capacitor so I have not been able to continue there. The resistances that your ampli mounted are 1Meg, while those that appear in the photo that you sent me are 10Meg, so I think they have already modified that part.
I have tried with another inverter valve in the power stage, I have set an ECC81 and the noise in 3dB is reduced, losing only 1.5dB of global gain but respecting the gain of the previous one. The problem is that trying on the "ear" does not sound good at all.
Conclusion:
I leave it as it was.
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