6SN7 Driver in Paramount 1.0 (Original with 12AT7)
- Thread starter galyons
- Start date
galyons
New member
johnsonad said:The white noise or hiss will drive you a little nutty at first. After a few weeks you'll realize that the music is sublime and forget about it.. I too would like a dead quiet circuit but the quality of sound is worth the added noise, at least for me.
I need to add that I moved from 100 dB sensitive to 95 dB and it still bothers me from time to time. That is, until I hit play
Aaron,
I agree. My system is not dead quiet, too many tubes! My listening position is about 12' from the speakers. Nearly dead quiet from there. Up close to the equipment & speakers there is low level tube rush.
Cheers,
Geary
Yeah, this is where support will get a little lean.
The power supply regulator has the 431 with fixed resistors. The "K" pad from this portion of the PCB, and the "O" pad that feeds the "+" linked to that 431 (should be "OA") need to hit the same half of the 6CG7 (1,2,3 or 6,7,8).
The driver stage will take the lower current "O" pad (OB most likely) and the K from the adjustable half of the board.
The power supply regulator has the 431 with fixed resistors. The "K" pad from this portion of the PCB, and the "O" pad that feeds the "+" linked to that 431 (should be "OA") need to hit the same half of the 6CG7 (1,2,3 or 6,7,8).
The driver stage will take the lower current "O" pad (OB most likely) and the K from the adjustable half of the board.
galyons
New member
Caucasian Blackplate said:
I understand. So the current fact is I now have 3 LM431’s in possible play.
LM431 -(1), is on the 9 pin socket, going from the center post, (ground) to B3 cathode.
LM431 -(2), was already on the driver board “A†side and is, before any changes, going to B8 cathode.
LM431 -(3), I added to the driver board “B†side along with the 2.49K @ R3 and 3.5K @ the outboard end of R4 & the inboard larger + pad. The new lead goes from the smaller, outboard + pad.
Caucasian Blackplate said:
If I understand correctly, this is LM431 (2). Then this circuit remains unchanged and the wire from KA remains on the cathode B8.
Caucasian Blackplate said:
So here is where we need to check my understanding. The added LM431 (3), 2.49K & 3.5K resistors are to change the driver cathode bias from 2.5v to 6.0v. If that is correct, then the new lead from "B" side K via "+" would go to B3.
Do I then need to remove the currently installed LM431 (1), (from the center post to B3)? Then wire the new lead from the new circuit with LM431 (3) to B3 to provide the 6.0v bias?
Or? Leave LM431 (1) in place, as is and add the new circuit lead to B3 and the combined old and new LM431 (1+3) will give me the desired 6.0v cathode bias?
OR? Just grab the closest bottle of Scotch and enjoy the Paramour 45's and try thinking again tomorrow!?
Thanks for hanging in with me on this!
Cheers,
Geary
The 431 on the socket needs to be removed - it is superseded by the 431 that you're adding to the PC board.
-PB
-PB
galyons
New member
Perfect. So once I do this all of the test voltages will remain the same, excepting:
B3 will now be 6.0v instead of 2.5V and
B9 will be 0 instead of 3.1V.
I am still waiting for parts to finish the second board. Maybe tomorrow? Will report when I am up and running.
Thank you for all of the support and guidance. Gotta go find that Scotch!!
Cheers,
Geary
B3 will now be 6.0v instead of 2.5V and
B9 will be 0 instead of 3.1V.
I am still waiting for parts to finish the second board. Maybe tomorrow? Will report when I am up and running.
Thank you for all of the support and guidance. Gotta go find that Scotch!!
Cheers,
Geary
Yeah, no doubt you may run into other oddities, just be sure to take your time and let us know if something isn't quite right.
-PB
-PB
galyons
New member
One amp is done!! Now I always thought that PB was perfect!! Well, he is not!! He clearly stated, earlier in the thread, that I would see bias rise from 2.5V to 6.0V on the B3 of the 6CG7. Not so! It is only 5.999V on my meter. ;D (I won't mention that the closest to the 3.5K resistor, (on the added LM431), I could get was 3.47K ohms!)
So the changes to the bias voltage were spot on! I did get close to 12v on the other cathode, B8. That is double the approximately 6V in the manual, but seems to follow doubling the bias voltage on C3?
Hard to judge the sonic effect, too soon and only mono. BUT, it sounds really nice, smoother, perhaps a little bit better HF extension. This is with an EH gold 300B. Will try my "good" non test 300B's after all is sorted.
Big plus, my system really likes the reduced gain. I will have to rework the resistors in my FP3X potentiometer circuit. So initial report....Yeah man!
The change to 6SN7/7N7/6CG7 works!! As a matter of fact, it works very well! Thanks PB & PJ!! PB is helping me on an issue with amp 2, but hope to be back to 300B stereo quite soon.
Cheers,
Geary
So the changes to the bias voltage were spot on! I did get close to 12v on the other cathode, B8. That is double the approximately 6V in the manual, but seems to follow doubling the bias voltage on C3?
Hard to judge the sonic effect, too soon and only mono. BUT, it sounds really nice, smoother, perhaps a little bit better HF extension. This is with an EH gold 300B. Will try my "good" non test 300B's after all is sorted.
Big plus, my system really likes the reduced gain. I will have to rework the resistors in my FP3X potentiometer circuit. So initial report....Yeah man!
The change to 6SN7/7N7/6CG7 works!! As a matter of fact, it works very well! Thanks PB & PJ!! PB is helping me on an issue with amp 2, but hope to be back to 300B stereo quite soon.
Cheers,
Geary
I'm glad to hear that you have one up and running, now you have a good reference point.
The 12V on the regulator Kreg is just where the cathode sits with the regulated B+ and the regulator triode drawing off the extra current provided by the "A" side C4S. Very, very generally speaking, more voltage gain=less voltage here, and less voltage gain=less cathode voltage. The voltage at that point must be above ~3V for the regulator to work, and once it's over about 30 volts, the regulator will pop, so there is a nice range of functionality.
The 12V on the regulator Kreg is just where the cathode sits with the regulated B+ and the regulator triode drawing off the extra current provided by the "A" side C4S. Very, very generally speaking, more voltage gain=less voltage here, and less voltage gain=less cathode voltage. The voltage at that point must be above ~3V for the regulator to work, and once it's over about 30 volts, the regulator will pop, so there is a nice range of functionality.
galyons
New member
I have had about three weeks of listening to the Paramounts with PB's driver tube bias mod to run 6CG7/6SN7/7N7 tubes. I am quite happy with the sound. I am currently using 6CG7's because that was the simplest, most expeditious route to getting the amps running. Bear in mind that this is NOT a comparison to V1.1 with 5760 Softstart. I haven't heard that configuration. My goals were to lower driver stage gain and use 6SN7ish tubes. Mission accomplished!
I have compared this configuration to my Paramour 2A3's and 45's. The 45's are tricked out with MQ BCP-15 plate chokes and EXO-045 Nickel parafeed OPT's. The 2A3's have BCP-15's and Altec Lansing OPT's. The Paramounts are stock iron. All of the amps are capped with PIO and Teflon caps in the signal stages. The 45's have been my prime amps for awhile. The mid range is magical with a palpable presence that is simply eerie. The Paramounts get close to the midrange while besting the 45's in low and high frequency extension. The 2A3's were closer to the Paramounts but were bested across all subjective parameters.
My speakers are a reworked '60's 3 way horn system with 102dB/1W/1m sensitivity. Preamp is an FP3 Extended with 6cg7's. I could easily live with any of the three amps, but the Paramounts, with the more "ballsy" sound, really make the speakers shine with a broader array of musical genre's than the 45's. I listen to mostly jazz, blues, female vocals and classical. The Paramounts get the job done very well on all genres, where the 45's were challenged with big orchestral classical and some of the higher energy blues recordings. I have been listening to Shuguang 50 Year Treasure black bottles and Russian Genelex Gold Lion 300B's. Hard to say which I like better. Either set sounds damn fine with only rather subtle differences.
The reduced gain is really a blessing. I was never getting past about 6 clicks, out of 24, on my stepped attenuators. Listening range now is 10-14 clicks with real steps getting there! Now I may even be able to eliminate the dropping resistors before the selector switch. The system just "likes" the newly reduced gain MUCH better!!
So now, as is ALWAYS the problem, I am now dreaming of MQ iron upgrades for the Paramounts!!! But next step is to tear the amps apart, anodize the top plate, paint the PT's and generally clean up some rather dodgy cosmetics. That will be the switch over point for the octal/loktal tubes. Until then, I am a happy listener!!
My thanks to PB & PJ for helping me get this done!!! (And the Queen, too!)
Cheers,
Geary
I have compared this configuration to my Paramour 2A3's and 45's. The 45's are tricked out with MQ BCP-15 plate chokes and EXO-045 Nickel parafeed OPT's. The 2A3's have BCP-15's and Altec Lansing OPT's. The Paramounts are stock iron. All of the amps are capped with PIO and Teflon caps in the signal stages. The 45's have been my prime amps for awhile. The mid range is magical with a palpable presence that is simply eerie. The Paramounts get close to the midrange while besting the 45's in low and high frequency extension. The 2A3's were closer to the Paramounts but were bested across all subjective parameters.
My speakers are a reworked '60's 3 way horn system with 102dB/1W/1m sensitivity. Preamp is an FP3 Extended with 6cg7's. I could easily live with any of the three amps, but the Paramounts, with the more "ballsy" sound, really make the speakers shine with a broader array of musical genre's than the 45's. I listen to mostly jazz, blues, female vocals and classical. The Paramounts get the job done very well on all genres, where the 45's were challenged with big orchestral classical and some of the higher energy blues recordings. I have been listening to Shuguang 50 Year Treasure black bottles and Russian Genelex Gold Lion 300B's. Hard to say which I like better. Either set sounds damn fine with only rather subtle differences.
The reduced gain is really a blessing. I was never getting past about 6 clicks, out of 24, on my stepped attenuators. Listening range now is 10-14 clicks with real steps getting there! Now I may even be able to eliminate the dropping resistors before the selector switch. The system just "likes" the newly reduced gain MUCH better!!
So now, as is ALWAYS the problem, I am now dreaming of MQ iron upgrades for the Paramounts!!! But next step is to tear the amps apart, anodize the top plate, paint the PT's and generally clean up some rather dodgy cosmetics. That will be the switch over point for the octal/loktal tubes. Until then, I am a happy listener!!
My thanks to PB & PJ for helping me get this done!!! (And the Queen, too!)
Cheers,
Geary
Hello Geary,
Do bear in mind that those resistors in the foreplay keep the input impedance reasonable.
If you remove them, you will need to replace the stock level controls with new ones (50-100K)
Do bear in mind that those resistors in the foreplay keep the input impedance reasonable.
If you remove them, you will need to replace the stock level controls with new ones (50-100K)
galyons
New member
Thanks Paul. I am running 100K attenuators and have 200k's as the dropping resistors. Never really been comfortable with this configuration, but it worked to get the gain down to somewhat usable. The attenuators are 0-75dB, so should be fine without the dropping resistors. (?)
Cheers,
Geary
Cheers,
Geary
Ah, good, yeah, you may find that you no longer need them.
So, how much different would these changes be in order to use the 6cg7 in the paramount 1.1 with soft start? Amps are not built yet, but SS boards are. If this is doable without major surgery to the SS board, then can I also assume that the 6sn7 will also work in much the same way?
Thanks,
Jim
Thanks,
Jim
johnsonad
New member
It you haven't heard the 5670, please give it a try. I've got a stash of them if you don't want to try and track them all down. If the 5670 doesn't cut it for you and if you can spare 6dB in gain then I would recommend trying the 6SN7. I've had the Paramounts with 12at7's and 5670's. For my system the 6sn7 was a better fit.
The spacers that come with the soft start kit will give you room to start with a 9 pin socket and later change to an 8 pin if you like. You are smart to over drill in the beginning. The socket is an easy rewire and I wouldn't lose too much sleep over that.
The spacers that come with the soft start kit will give you room to start with a 9 pin socket and later change to an 8 pin if you like. You are smart to over drill in the beginning. The socket is an easy rewire and I wouldn't lose too much sleep over that.
