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Old 17th February 2011, 02:35 PM   #141
zbodeoc is offline zbodeoc  Romania
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Hi there,

I have both versions of 6P3C (plenty) but I didn't try the longer one, if you can believe me. I was told and I have read that 6P3C-E is a military release, more rugged and powerful and I only put this tube in amplifier. By the time when I posted my improvements' list the time allocated for this project elapsed too and I didn't change anything since. Nevertheless, I do enjoy the sound of that amplifier almost every day. One year ago I had the chance to compare one untouched MC-5881 with mine and the difference is huge, as I was expected.

I'll let you know how the longer ones sound in the following period, days, I don't know when exactly.

You can see here the tubes side by side (pay attention that the shorter version is ticker):
http://store01.myfastshare.com/FastS...70DBD3F6210BB2

Last edited by zbodeoc; 17th February 2011 at 02:49 PM.
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Old 28th February 2011, 05:47 PM   #142
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Quote:
Originally Posted by zbodeoc View Post
Hi there,

I have both versions of 6P3C (plenty) but I didn't try the longer one, if you can believe me. I was told and I have read that 6P3C-E is a military release, more rugged and powerful and I only put this tube in amplifier. By the time when I posted my improvements' list the time allocated for this project elapsed too and I didn't change anything since. Nevertheless, I do enjoy the sound of that amplifier almost every day. One year ago I had the chance to compare one untouched MC-5881 with mine and the difference is huge, as I was expected.

I'll let you know how the longer ones sound in the following period, days, I don't know when exactly.

You can see here the tubes side by side (pay attention that the shorter version is ticker):
Download fisier
I live in my own house, so i can use Yaqin 5881 at full power whenever i want.
My 5881 is helped with nice Yamaha P3500 power plant, both amps are driven thru prototype of Slovenian Stylos tube DAC, as an premplifier.
6moons audio reviews: Stylos sys HAD*D/A converter

My Tube DAC proto has almost the same DAC converter as ougly solid state coffin in the link, but it uses ECC88 buffer.
I have 8 drivers per channel in my DIY speakers.

My 5881 is powering per channel 2 Tannoy dynamic tweeters, one dipole bending wawe transformer, one ribbon planar horn, one 13 and one 16cm Tannoy midbass(all other drivers are powered by Yamaha, each driver has it s own speaker wire, 8X per ch) and it is doing this job really excellent! 6 drivers per ch...
Efficency of my driver set is approx. 87Db/m, power of both amps "working" simultaneously, is huge, sound, clear and silky no matter how much power is in "the game".

When i ll finish speakers, i will try some of your tweaks in my Yaqin.
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Old 5th May 2011, 09:54 AM   #143
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Update.
I equipped all tubes with simple and cheap silicone tube dampers.
Bye, bye micro oscillations. Wouldn't believe if someone told me so.
Like someone said. "Why silicone rings aren't fitted on every tube amp in factory?"

Also ordered Tungsram and RFT ECC85 tubes and indeed, Tungsram ECC85 fits like a glove in 5881. Wonderful depth of stage.
Triode Al is wright about ECC85.
Tungsram in combo with Vostok 6N1P EV from 70 ies is tremendously musical, one of my favourites, but RFT is a disappointment.
They have a superb stereo separation,(i don't need it, if there are other tubes showing a stage as a whole), they have no depth, odd two dimensional presentation, they superbly shows micro details, but they sounds boring, graveyard boring.
They have strong and precise bass, but it is bit lifted to the mid tone area, good for people preferring mainstream car audio sound.
Good tubes for audio masochists. Pitty, they have also very good gain.
Another good combo is Tungsram ECC85-JJ E88CC.
Rich in subtle musical information, powerful, stage is more in front then with 6N1P EV, pure pleasure.
Power cable im using at the moment is VH Audio DIY on chinese Oyaide079 schuko copy. Good stuff, great slam, very even in whole spectre, more on analytical side, so musicality has to be "milked" from more musical tubes and with changing of some passive components for those with more musical character.
This will probably be Nichicon Muse or Elna Silmic, Dale, and Eichmann Phonopod RCA(dream like non problematic stuff, specially if you use Eichmann Silver and Copper Bullet plugs and Tempoelectric wiring), also I ll try Alps Blue and Gigaworks pottis on Tempoelectric inner wiring bypassing the source selector, no need for more sources, because i have only one source, music server on tube DAC.

I also ordered RCA 9AQ8 / PCC85, to try those ones which have slightly higher gain then 6N1.

I just love sound, good control, slam and speed of transients and rewarding modding potential of 5881.
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Old 13th May 2011, 04:21 AM   #144
pjstone is offline pjstone  United States
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I just want the express my gratitude to you fine folks for figuring out the hard stuff. I have made the mod to my main by tapping into the 3rd winding and cutting out the extra 500 ohm resistors. it took me maybe an hour and now i am running nice and cool. i can turn the volume up more now and really enjoy my tannoy arden's!! Thanks again!

Phil
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Old 15th May 2011, 12:32 AM   #145
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JJ's are good enough for this model. Be careful with the heat specs on those replacement caps. This model and the MC-84L gets extremely hot. **This thread is yet another example of the need for a separate. specific Yaqin forum for Yaqin products only!
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Old 15th May 2011, 04:18 PM   #146
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As regarding the mod to remove one of the cathode resistors: the remaining one can get hot; and one failed.
No problem: there is just almost no sound from the one channel.

So I replaced them with a version that can be mounted on a heatsink. (Actually I added a little heatsink on the back of the cabinet - I could not drill a hole in the stainless steel to attach the resistor.) I don't have a picture.
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Old 16th May 2011, 06:25 PM   #147
pjstone is offline pjstone  United States
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good to know the single resistor gets hot. i didn't even check that. guess i better get a good replacement.

Thanks!
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Old 20th May 2011, 10:44 AM   #148
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In mine 5881 there were Nichicon for audio series and BC electrolytic caps.
I assume that s a result of the constant efforts of the French Yaquin importer, Marc, very helpful and nice character person and his constant travelling in China factories in order to improve their products in a way to suit more EU and USA buyers expectations.

I would like to discuss bit unordinary tubes which makes sonically perfect match for a pair of Tungsram ECC85 in my 5881.
Just love them.

They are NOS, W.Germany originated, i assume from 50ies(decay of cellulose boxes), Canadian branded, army type.

I note in my tube manual that the 6DJ8 is listed as having a nominal u (amplification factor) of 33, while the 7ES8 is listed here as having a nominal u of 65. Perhaps operating the 7ES8 with only 6.3 volts on its filament, as opposed to the specified 7.6 volts, would bring those figures closer together. But I would not expect anything better than a rough approximation, which at best would be good enough sonically only in some circuit applications.

Definiton of difference between ECC-PCC

An electron tube in which the amplification factor varies in a predetermined manner with control-grid voltage; this characteristic is achieved by making the spacing of the grid wires vary regularly along the length of the grid, so that a very large negative grid bias is required to block anode current completely. Also known as remote-cutoff tube.

By all means small and unimportant difference, i think(i could be wrong).
No need to block negative current in preamp, no neeed for controlling variable grid voltage.

7ES8 Amplification factor is considerably higher and in mine 5881 the result is more linearity then with any other signal tube (i have plenty of different ones suitable to tech. specs. of 5881).
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Old 20th May 2011, 11:11 AM   #149
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Quote:
Originally Posted by pjstone View Post
good to know the single resistor gets hot. i didn't even check that. guess i better get a good replacement.

Thanks!
Hello. Very good result on the heaters. Calculation proved spot on. They get so hot (your 5W resistors) because they get to dissipate almost 7W as a whole. That is why I specified 2X10W. In general, for no long term problems, a resistor must have a rating 3X the actual dissipation and over. So 20W total will be OK.

Yaqin MC-5881A amplifier improvements
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Old 9th June 2011, 04:53 PM   #150
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Quote:
Originally Posted by CityPooh View Post
In mine 5881 there were Nichicon for audio series and BC electrolytic caps.
I assume that s a result of the constant efforts of the French Yaquin importer, Marc, very helpful and nice character person and his constant travelling in China factories in order to improve their products in a way to suit more EU and USA buyers expectations.

I would like to discuss bit unordinary tubes which makes sonically perfect match for a pair of Tungsram ECC85 in my 5881.
Just love them.

They are NOS, W.Germany originated, i assume from 50ies(decay of cellulose boxes), Canadian branded, army type.

I note in my tube manual that the 6DJ8 is listed as having a nominal u (amplification factor) of 33, while the 7ES8 is listed here as having a nominal u of 65. Perhaps operating the 7ES8 with only 6.3 volts on its filament, as opposed to the specified 7.6 volts, would bring those figures closer together. But I would not expect anything better than a rough approximation, which at best would be good enough sonically only in some circuit applications.

Definiton of difference between ECC-PCC

An electron tube in which the amplification factor varies in a predetermined manner with control-grid voltage; this characteristic is achieved by making the spacing of the grid wires vary regularly along the length of the grid, so that a very large negative grid bias is required to block anode current completely. Also known as remote-cutoff tube.

By all means small and unimportant difference, i think(i could be wrong).
No need to block negative current in preamp, no neeed for controlling variable grid voltage.

7ES8 Amplification factor is considerably higher and in mine 5881 the result is more linearity then with any other signal tube (i have plenty of different ones suitable to tech. specs. of 5881).
After a month of using ancient NOS Canadian-W.Germany originated PCC189, i can only say, that that is the far best signal tube i have in my collection.
GE Sylvania 6922, RCA PCC85(probably made on Mullard tooling) are good ones(just today arrived Philips PCC85 to "compete" with those), also Tungsram PCC85 and 6N1P-EV are also very nice.
All those have nice, but, very different characters. All of my other tubes PCC,ECC,E88CC, i have are not so suitable for 5881.

Considering that only that German PCC189 sounds, lets say, almost like perfect of all those, despite that, that a lot of audiophiles are claiming, that PCC189 can not work as audio signal tube.
Praxis shows opposite.
PCC189 in my case is more then "seaworthy" signal tube in ECC85 audio application. Period.
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