Comments for Yaqin Tube Valve Amplifiers http://yaqin.slickpepper.org.uk A site dedicated to affordably priced yet high quality Yaqin tube audio equipment Wed, 10 Mar 2010 09:20:19 +0000 http://wordpress.org/?v=2.9.1 hourly 1 Comment on MC-100B by Higher quality MC-100B schematic is here | Yaqin Tube Valve Amplifiers http://yaqin.slickpepper.org.uk/amplifiers/yaqin-mc-100b/comment-page-1#comment-499 Higher quality MC-100B schematic is here | Yaqin Tube Valve Amplifiers Wed, 10 Mar 2010 09:20:19 +0000 http://yaqin.slickpepper.org.uk/?page_id=146#comment-499 [...] http://yaqin.slickpepper.org.uk/amplifiers/yaqin-mc-100b [...] [...] http://yaqin.slickpepper.org.uk/amplifiers/yaqin-mc-100b [...]

]]> Comment on MC-10L by marc http://yaqin.slickpepper.org.uk/amplifiers/mc-10l/comment-page-2#comment-494 marc Mon, 08 Mar 2010 02:55:20 +0000 http://yaqin.slickpepper.org.uk/?page_id=5#comment-494 HI Les, I put the resistors in only being 820Ohm @ 5w from pins 4 G2 to the transformer and it did make a slight diffrence, i used a tone generator to see what it was before and afterwards, using a ( CRO ) that takes pricture print-outs, your right a bit of a diffrence not much, but something is better than nothing. I had not put the Capacitors in and i belive the V-rating should be a bit higher as if the 10Ohm resistor goes O/C then they may be more than 63V there at worst. ( Hope not ) This may help one of the readers i used Winged "C" 6n1P tubes -- The worst i ended up obntaining hum from one channel, with the 4 tubes inserted and swapping them all around, i found all tubes had a slight diffrent current draw, using the ( CRO ) taking 2 out and using Normal 6N1 tubes or Russian 6N1EB(EV) all okay.. I have used as well the 6992 Tubes the China ones where terrible with Microphonics. I used Amprex ( Bugle boy ) tubes *2 and there was a plesent tone increase, more a warmer sound, not harsh.. They matched well with my RFT-EL34 Seimens Tubes so the MC-10L sound like a better amp for it.... See how you go and what you think Marc. If this Comment comes up twice, it stated did not upload, so had to re-write sorry to all !! HI Les,
I put the resistors in only being 820Ohm @ 5w from pins 4 G2 to the transformer and it did make a slight diffrence, i used a tone generator to see what it was before and afterwards, using a ( CRO ) that takes pricture print-outs, your right a bit of a diffrence not much, but something is better than nothing. I had not put the Capacitors in and i belive the V-rating should be a bit higher as if the 10Ohm resistor goes O/C then they may be more than 63V there at worst. ( Hope not ) This may help one of the readers i used Winged “C” 6n1P tubes — The worst i ended up obntaining hum from one channel, with the 4 tubes inserted and swapping them all around, i found all tubes had a slight diffrent current draw, using the ( CRO ) taking 2 out and using Normal 6N1 tubes or Russian 6N1EB(EV) all okay.. I have used as well the 6992 Tubes the China ones where terrible with Microphonics. I used Amprex ( Bugle boy ) tubes *2 and there was a plesent tone increase, more a warmer sound, not harsh.. They matched well with my RFT-EL34 Seimens Tubes so the MC-10L sound like a better amp for it…. See how you go and what you think Marc.
If this Comment comes up twice, it stated did not upload, so had to re-write sorry to all !!

]]> Comment on MC-10L by marc http://yaqin.slickpepper.org.uk/amplifiers/mc-10l/comment-page-2#comment-493 marc Mon, 08 Mar 2010 02:39:01 +0000 http://yaqin.slickpepper.org.uk/?page_id=5#comment-493 To Les..I put the resistors on Pin 4 of every El34 Tube = G2 between the Socket and the windings of the TX ( transformer ) with our putting the 220Uf@63v cap over the 10Ohm reistor, As i tried a experiment if the resistor goes O/C and things go wrong you could end up with close to 100V there, so i belive the caps should be 220Uf @160V. Any way with out the caps yes i agree there is a slight low end tonal increase, i put heat shrink over the resistors to protect the circuits . The 6992 experiment.. I can report this, some of the China 6992's are Rubish, to much microphonics... How ever the Amperex ( bugle Boy ) sound warm and inviting, though expensive, I agree with one of your testings i found using Wing "C" 6N1P EV they where not to good, Infact this may help one of the people with slight hum on one channel. when using the Winded "C" i found that on one channel i was getting a hum, Swapping the tupes ( driver stage ) around made the hum decrease, i found itn was poor quality of the Winged "C" and the CVurrent draw was a bit higher, i noted on the "CRO" that there was ripple on the power lines using these tubes. Took them out and went back to Russian 6N1EB all okay or 6N1 tubes.. I also have used on the output of the MC-10L RFT El34 Tubes hard to come by though a great over all improvment in sound quality down low, very nice and warm. good detail and something you can listern to for ages.. Sadly there NOT made any more though you will still find them around. marc To Les..I put the resistors on Pin 4 of every El34 Tube = G2 between the Socket and the windings of the TX ( transformer ) with our putting the 220Uf@63v cap over the 10Ohm reistor, As i tried a experiment if the resistor goes O/C and things go wrong you could end up with close to 100V there, so i belive the caps should be 220Uf @160V. Any way with out the caps yes i agree there is a slight low end tonal increase, i put heat shrink over the resistors to protect the circuits .

The 6992 experiment.. I can report this, some of the China 6992’s are Rubish, to much microphonics… How ever the Amperex ( bugle Boy ) sound warm and inviting, though expensive, I agree with one of your testings i found using Wing “C” 6N1P EV they where not to good, Infact this may help one of the people with slight hum on one channel. when using the Winded “C” i found that on one channel i was getting a hum, Swapping the tupes ( driver stage ) around made the hum decrease, i found itn was poor quality of the Winged “C” and the CVurrent draw was a bit higher, i noted on the “CRO” that there was ripple on the power lines using these tubes. Took them out and went back to Russian 6N1EB all okay or 6N1 tubes..
I also have used on the output of the MC-10L RFT El34 Tubes hard to come by though a great over all improvment in sound quality down low, very nice and warm. good detail and something you can listern to for ages.. Sadly there NOT made any more though you will still find them around.
marc

]]> Comment on MC-10L by marc http://yaqin.slickpepper.org.uk/amplifiers/mc-10l/comment-page-2#comment-492 marc Mon, 08 Mar 2010 02:38:42 +0000 http://yaqin.slickpepper.org.uk/?page_id=5#comment-492 To Les..I put the resistors on Pin 4 of every El34 Tube = G2 between the Socket and the windings of the TX ( transformer ) with our putting the 220Uf@63v cap over the 10Ohm reistor, As i tried a experiment if the resistor goes O/C and things go wrong you could end up with close to 100V there, so i belive the caps should be 220Uf @160V. Any way with out the caps yes i agree there is a slight low end tonal increase, i put heat shrink over the resistors to protect the circuits . The 6992 experiment.. I can report this, some of the China 6992's are Rubish, to much microphonics... How ever the Amperex ( bugle Boy ) sound warm and inviting, though expensive, I agree with one of your testings i found using Wing "C" 6N1P EV they where not to good, Infact this may help one of the people with slight hum on one channel. when using the Winded "C" i found that on one channel i was getting a hum, Swapping the tupes ( driver stage ) around made the hum decrease, i found itn was poor quality of the Winged "C" and the CVurrent draw was a bit higher, i noted on the "CRO" that there was ripple on the power lines using these tubes. Took them out and went back to Russian 6N1EB all okay or 6N1 tubes.. I also have used on the output of the MC-10L RFT El34 Tubes hard to come by though a great over improvment in sound quality down low, very nice and warm. good detail and something you can listern to for ages.. Sadly there NOT made any more though you will still find them around. marc To Les..I put the resistors on Pin 4 of every El34 Tube = G2 between the Socket and the windings of the TX ( transformer ) with our putting the 220Uf@63v cap over the 10Ohm reistor, As i tried a experiment if the resistor goes O/C and things go wrong you could end up with close to 100V there, so i belive the caps should be 220Uf @160V. Any way with out the caps yes i agree there is a slight low end tonal increase, i put heat shrink over the resistors to protect the circuits .

The 6992 experiment.. I can report this, some of the China 6992’s are Rubish, to much microphonics… How ever the Amperex ( bugle Boy ) sound warm and inviting, though expensive, I agree with one of your testings i found using Wing “C” 6N1P EV they where not to good, Infact this may help one of the people with slight hum on one channel. when using the Winded “C” i found that on one channel i was getting a hum, Swapping the tupes ( driver stage ) around made the hum decrease, i found itn was poor quality of the Winged “C” and the CVurrent draw was a bit higher, i noted on the “CRO” that there was ripple on the power lines using these tubes. Took them out and went back to Russian 6N1EB all okay or 6N1 tubes..
I also have used on the output of the MC-10L RFT El34 Tubes hard to come by though a great over improvment in sound quality down low, very nice and warm. good detail and something you can listern to for ages.. Sadly there NOT made any more though you will still find them around.
marc

]]> Comment on MC-10L by Les http://yaqin.slickpepper.org.uk/amplifiers/mc-10l/comment-page-2#comment-486 Les Fri, 05 Mar 2010 23:54:52 +0000 http://yaqin.slickpepper.org.uk/?page_id=5#comment-486 Hi Marc, I did exactly what you propose to do, keep 6N1 in the V2-V3 positions but fit alternative types in the V1-V4 positions. I tried ECC85's but they were not happy here even though they appeared to sound sweet. Micro-phonics were a problem and for some strange reason the right channel would oscillate at around 14kHz. I tried GE, Mullard and Mazda tubes but the micro-phonics remained a problem so I went back to using Svetlana 6N1 golds which I think are the best versions of this tube. These seem to have dried up now and the much heralded Svetlana winged C have been a disappointment to me. I have not tried ECC88/6992 but whatever you do take care of the cathode to heater ratings as the 6N1 does have a higher spec than some other possible tube alternatives. I notice that some MC10L owners are raving about the fitting of 6P3S tubes to replace the EL34's in the output. This is dangerous! The 6P3S has a maximum anode (plate) voltage of around 250V yet the MC10L has a B+ supply of around 450V, I don't think I would ever consider using 6P3S tubes for this very reason. It highlights how careful you have to be, always check up on each valves maximum ratings before opting for an alternative. The cathode to heater voltage ratings of the ECC88 seem to be good enough, if you try them let us know if you have any instability or micro-phonic problems with them. Les Hi Marc, I did exactly what you propose to do, keep 6N1 in the V2-V3 positions but fit alternative types in the V1-V4 positions. I tried ECC85’s but they were not happy here even though they appeared to sound sweet. Micro-phonics were a problem and for some strange reason the right channel would oscillate at around 14kHz. I tried GE, Mullard and Mazda tubes but the micro-phonics remained a problem so I went back to using Svetlana 6N1 golds which I think are the best versions of this tube. These seem to have dried up now and the much heralded Svetlana winged C have been a disappointment to me. I have not tried ECC88/6992 but whatever you do take care of the cathode to heater ratings as the 6N1 does have a higher spec than some other possible tube alternatives. I notice that some MC10L owners are raving about the fitting of 6P3S tubes to replace the EL34’s in the output. This is dangerous! The 6P3S has a maximum anode (plate) voltage of around 250V yet the MC10L has a B+ supply of around 450V, I don’t think I would ever consider using 6P3S tubes for this very reason. It highlights how careful you have to be, always check up on each valves maximum ratings before opting for an alternative.
The cathode to heater voltage ratings of the ECC88 seem to be good enough, if you try them let us know if you have any instability or micro-phonic problems with them.
Les

]]> Comment on MC-10L by marc http://yaqin.slickpepper.org.uk/amplifiers/mc-10l/comment-page-2#comment-483 marc Thu, 04 Mar 2010 09:22:19 +0000 http://yaqin.slickpepper.org.uk/?page_id=5#comment-483 Dear Les, Sorry i wanted to ask the Yaqin MC-10L mk2 uses the 6N1 high gain tubes. V1 and V4 are the pre-amp tubes and V2-V3 are the drivers if im correct. Can they be replaced with 6992 tubes, all information seems to show there identical, though on the Yaqin from what i can see in the circuit i had to re-draw as there circuit is wrong, the 6N1 are driven a bit harder. If you can said any light on the subject, it would help just to have a nicer pre-amp stage.. Even if i only replace V1 and V4 tubes and put V2*3 to 6N1PEB (EV ) same tube regards Dear Les,

Sorry i wanted to ask the Yaqin MC-10L mk2 uses the 6N1 high gain tubes. V1
and V4 are the pre-amp tubes and V2-V3 are the drivers if im correct.

Can they be replaced with 6992 tubes, all information seems to show there
identical, though on the Yaqin from what i can see in the circuit i had to
re-draw as there circuit is wrong, the 6N1 are driven a bit harder.
If you can said any light on the subject, it would help just to have a nicer
pre-amp stage.. Even if i only replace V1 and V4 tubes and put V2*3 to
6N1PEB (EV ) same tube

regards

]]> Comment on MC-10L by Les http://yaqin.slickpepper.org.uk/amplifiers/mc-10l/comment-page-2#comment-480 Les Wed, 03 Mar 2010 23:30:56 +0000 http://yaqin.slickpepper.org.uk/?page_id=5#comment-480 Sorry for the late replies but I have had problems getting to these later posts, each time I visit, the last post shown is for July 2009, crazy! Anyhow tonight I managed to get back in so that I can leave a comment. To Stephen, as you only have hum on one channel I would not suspect a problem with the bias supply as this would affect both. Have you tried swapping valves from one channel to the other? Just in case you have a rogue valve. This hum problem that others also have found puzzles me somewhat as the MC10-L is such a very quiet amplifier and I look with interest for your eventual findings for this problem. To Marc, yes I fitted the components as stated. What happened here was that I had to repair a £2k high end amplifier that had these components fitted and yes it also had the same value cathode resistors that the MC10-L uses. I had read of many occurrences where EL34's had flashed over in the MC10-L and I just put this down to a probable faulty EL34. However, some research and subsequent reading of Philips (Mullard) data for the EL34 gave me the info that the EL34 should have a 470 Ohm to 1k Ohm screen resistor. The manufacturers of the high end amplifier had obviously gone half way and actually fitted 750 Ohm resistors so I took the next best value of 820 Ohms. After doing the additions, I am afraid that the MC10-L still did not have the gorgeous bass of the high end amplifier, probably due to the very expensive multiple interleaved windings of its output transformers. But the bass was definitely improved on the MC10-L, quite noticeable on some CD's, it is not a lot but I think worth the effort. Also as I said before, you have nothing to lose as the extra parts are of little cost and you can always revert back to the original circuit later if you so wish. All the best, Les Sorry for the late replies but I have had problems getting to these later posts, each time I visit, the last post shown is for July 2009, crazy! Anyhow tonight I managed to get back in so that I can leave a comment.
To Stephen, as you only have hum on one channel I would not suspect a problem with the bias supply as this would affect both. Have you tried swapping valves from one channel to the other? Just in case you have a rogue valve. This hum problem that others also have found puzzles me somewhat as the MC10-L is such a very quiet amplifier and I look with interest for your eventual findings for this problem.
To Marc, yes I fitted the components as stated. What happened here was that I had to repair a £2k high end amplifier that had these components fitted and yes it also had the same value cathode resistors that the MC10-L uses. I had read of many occurrences where EL34’s had flashed over in the MC10-L and I just put this down to a probable faulty EL34. However, some research and subsequent reading of Philips (Mullard) data for the EL34 gave me the info that the EL34 should have a 470 Ohm to 1k Ohm screen resistor. The manufacturers of the high end amplifier had obviously gone half way and actually fitted 750 Ohm resistors so I took the next best value of 820 Ohms. After doing the additions, I am afraid that the MC10-L still did not have the gorgeous bass of the high end amplifier, probably due to the very expensive multiple interleaved windings of its output transformers. But the bass was definitely improved on the MC10-L, quite noticeable on some CD’s, it is not a lot but I think worth the effort. Also as I said before, you have nothing to lose as the extra parts are of little cost and you can always revert back to the original circuit later if you so wish.
All the best, Les

]]> Comment on Yaqin Service by stephen http://yaqin.slickpepper.org.uk/yaqin-service/comment-page-1#comment-474 stephen Mon, 01 Mar 2010 22:30:14 +0000 http://yaqin.slickpepper.org.uk/?page_id=18#comment-474 The mc 10-l I have is a lovely looking amplifier but the mains hum from both channels (mainly right side) Is driving me mad!! I live in the uk my supply measures 244v (quite high but within tolerance) Ive tried changing the capacitors but I'm beginning to think its the actual power supply transformer as its becoming noisier as are the hum from the speakers has anybody had any similar experiences? The mc 10-l I have is a lovely looking amplifier but the mains hum from both channels (mainly right side) Is driving me mad!! I live in the uk my supply measures 244v (quite high but within tolerance) Ive tried changing the capacitors but I’m beginning to think its the actual power supply transformer as its becoming noisier as are the hum from the speakers has anybody had any similar experiences?

]]> Comment on MS-34D by MC100B and MS-34D schematics added | Yaqin Tube Valve Amplifiers http://yaqin.slickpepper.org.uk/amplifiers/ms-34d/comment-page-1#comment-472 MC100B and MS-34D schematics added | Yaqin Tube Valve Amplifiers Mon, 01 Mar 2010 13:55:41 +0000 http://yaqin.slickpepper.org.uk/?page_id=136#comment-472 [...] http://yaqin.slickpepper.org.uk/amplifiers/ms-34d [...] [...] http://yaqin.slickpepper.org.uk/amplifiers/ms-34d [...]

]]> Comment on MC-100B by MC100B and MS-34D schematics added | Yaqin Tube Valve Amplifiers http://yaqin.slickpepper.org.uk/amplifiers/yaqin-mc-100b/comment-page-1#comment-471 MC100B and MS-34D schematics added | Yaqin Tube Valve Amplifiers Mon, 01 Mar 2010 13:55:23 +0000 http://yaqin.slickpepper.org.uk/?page_id=146#comment-471 [...] http://yaqin.slickpepper.org.uk/amplifiers/yaqin-mc-100b [...] [...] http://yaqin.slickpepper.org.uk/amplifiers/yaqin-mc-100b [...]

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