New Destop Tube Amplifer, ECC85-6L6 class A Single End - diyAudio
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Old 13th June 2010, 05:58 AM   #1
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Default New Destop Tube Amplifer, ECC85-6L6 class A Single End

We are glad to build a new destop 6L6 single end amplifer in class A circuit. This time we specially selected double triode tube, ECC85 in the voltage amplifying stage. ECC85/6AQ8/B719 are widely used in RF amplifiers and FM radio receivers in 1950s. We now can find Telefunken, Mullard, Brimar, RFT, Tungsram ECC85 in the market and the prices are not expensive. People always believe ECC83/12AX7 is one of the greatest triode and pay high cost to buy ECC83, ECC803S, etc. Now Thomas designed a simple circuit for ECC85-6L6 single end with 5Z4 rectifier. It is the one of best sound of 6L6 single end we made. It is time to listen ECC85 and discover its potential.

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Last edited by Musik007; 13th June 2010 at 06:54 AM.
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Old 13th June 2010, 01:41 PM   #2
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The dimension of the 6L6 amplifer is 290W x 260D(with knob and binding posts) x 175Hmm. It is much smaller than EF95-6V6 desktop amplifer.
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File Type: jpg 6L6-6V6-2.jpg (805.0 KB, 694 views)
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Old 13th June 2010, 01:49 PM   #3
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This old Beijing 6N1J, military graded tube can be directly replaced with ECC85.
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Old 13th June 2010, 02:40 PM   #4
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This old Chinese Shuguang 6P3P in ST shape can be directly replaced with 6L6. They were manufactured during 1960s and 1980s in one of the largest tube factory in China, Shuguang. Most of 6P3P are military graded.

The output power of 6P3P or 6L6 in class A single end in Pentode connection is 6.5W.
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File Type: jpg 6L6-1-10.jpg (796.7 KB, 67 views)
File Type: jpg 6L6-1-11.jpg (797.5 KB, 42 views)

Last edited by Musik007; 13th June 2010 at 04:13 PM.
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Old 13th June 2010, 02:46 PM   #5
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Shuguang 5Z4P is a low-priced with high performance rectificaction tube.
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Old 13th June 2010, 02:52 PM   #6
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The price of this 6P3P amplifier is USD398 with Chinese tubes.
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Old 14th June 2010, 03:07 PM   #7
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Tony brought this new 6L6 amp to me for an extended listening test. I'll run the amp for a new weeks to see how it gets along with the Alpair 6 paper cone prototypes. I spent most of the afternoon with the amp running in the background with periods of intense listening to several test tracks.

Immediate impressions are "this is a gem of an amp". Tony and Thomas have made several small amps in recent months, I'd say this 6L6 is likely the best so far. The first thing that came across was detail and depth, mixed with excellent stereo separation, Thomas's design is quite remarkable. Middle and high ranges are the best points while the bass is reasonably strong although their 6V6 unit is slightly stronger is this respect. All the same, its the detail that makes this amp quite remarkable, all done without being harsh or artificial.

Given that this sample amp is running on cheap Chinese brand tubes, up-grading the tubes would be a very interesting prospect.

Well done Tony and Thomas!

Cheers

Mark.
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Old 21st June 2010, 03:40 PM   #8
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Hi Mark,

Any improvement for the sound of the amp in a week?

Input stage is very important for sound characteristics of a tube amp. The output power of this 6L6SE is 6.5W and the output is 4W for that EF95-6V6SE amp. Both are in pentode connections. However, you may think the EF95-6V6SE is a more powerful than ECC85-6L6SE because the input stage is EF95 pentode in that 6V6SE. Pentode EF95 is stronger and more powerful than troide ECC85, but ECC85 is smoother and softer than EF95. They are different.

I tried East German RFT ECC85 in this amp, the sound is more refined than the China 6N1.

Thanks very much for your comments.

Tony.
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Old 22nd June 2010, 06:49 AM   #9
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Quote:
Originally Posted by Musik007 View Post
Hi Mark,

Any improvement for the sound of the amp in a week?
Input stage is very important for sound characteristics of a tube amp. The output power of this 6L6SE is 6.5W and the output is 4W for that EF95-6V6SE amp. Both are in pentode connections. However, you may think the EF95-6V6SE is a more powerful than ECC85-6L6SE because the input stage is EF95 pentode in that 6V6SE. Pentode EF95 is stronger and more powerful than troide ECC85, but ECC85 is smoother and softer than EF95. They are different. I tried East German RFT ECC85 in this amp, the sound is more refined than the China 6N1.

Thanks very much for your comments.
Tony.
Hi Tony,
Very interesting having given this amp around 30 hours. Still sounding "new" but now plays with a touch more warmth. Thomas needs to make an adjustment on this prototype amp regarding the volume control but should be a easy job.

I agree its worth experimenting with other makes of valve (tube). Although, I have to say theses Chinese valves are surprising good given their low cost. I wouldn't change them just yet. I'd like to get 800 to 1000 hours out of the Chinese valves before looking for alternatives. Overall, this amp is impressive when mated with the Alpair 6 paper prototypes!

Cheers

Mark.

Last edited by markaudio; 22nd June 2010 at 06:52 AM. Reason: typo mending
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Old 22nd June 2010, 02:50 PM   #10
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Hi Mark,

Try to transpose 6N1 from left channel to right channel firstly. If it is problem of tube, you can easily hear from that channel. If there is no problem for 6N1, then try 6L6.

Thank you very much for your comments.

Tony.

Quote:
Originally Posted by markaudio View Post
Hi Tony,
Very interesting having given this amp around 30 hours. Still sounding "new" but now plays with a touch more warmth. Thomas needs to make an adjustment on this prototype amp regarding the volume control but should be a easy job.

I agree its worth experimenting with other makes of valve (tube). Although, I have to say theses Chinese valves are surprising good given their low cost. I wouldn't change them just yet. I'd like to get 800 to 1000 hours out of the Chinese valves before looking for alternatives. Overall, this amp is impressive when mated with the Alpair 6 paper prototypes!

Cheers

Mark.
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