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SE 6L6 power amp, 12AT7 driver (design by Suncalc)
http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=5731
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Author:  mwhouston [ 26 Jan 2017, 06:50 ]
Post subject:  Re: SE 6L6 power amp, 12AT7 driver (design by Suncalc)

Just took a look on Tubedepot to find the JJ tubes I have to be not that expensive. I bought mine years ago. I notice they also had NOS metal 6L6s for US$30 each.

Matt, I have some new 5881 Ekectro-Harmonix. Would these be a better alternative to the 6L6 in the current amp. I think you expressed the EL34s may not be the best.

Author:  Chris65 [ 26 Jan 2017, 18:03 ]
Post subject:  Re: SE 6L6 power amp, 12AT7 driver (design by Suncalc)

Quote:
mwhouston wrote:
Just took a look on Tubedepot....I notice they also had NOS metal 6L6s for US$30 each

That's at the top end, they can be found for $15-20. There are other 6L6 variants you might consider: 1614, 1622, 6P3S, or EL37 (some say the best 6L6 version).

Author:  Suncalc [ 26 Jan 2017, 18:03 ]
Post subject:  Re: SE 6L6 power amp, 12AT7 driver (design by Suncalc)

mwhouston wrote:
I have some new 5881 Ekectro-Harmonix. Would these be a better alternative to the 6L6 in the current amp.
The 5881 was a ruggedized 6L6G with plate and screen dissipations increased from 19W and 2.5W to 26W and 3W respectively. The 6L6GC further boosted dissipations to 30W and 5W. I think you will find that most new stock 5881 beam power tubes are identical to the 6L6GC offering. So probably not much difference.

I know that in the 6V6 I much prefer the JJ to the EH tubes. I have JJ 6L6GC but have never tried the EH 5881 or 6L6 tubes. I had a bad experience with some EH signal tubes that kind of tainted my view of EH. My guess is that they'll be a little different, but as to better or worse, only a try out will tell you that.

Author:  mwhouston [ 26 Jan 2017, 23:22 ]
Post subject:  Re: SE 6L6 power amp, 12AT7 driver (design by Suncalc)

Suncalc wrote:
mwhouston wrote:
I have some new 5881 Ekectro-Harmonix. Would these be a better alternative to the 6L6 in the current amp.
The 5881 was a ruggedized 6L6G with plate and screen dissipations increased from 19W and 2.5W to 26W and 3W respectively. The 6L6GC further boosted dissipations to 30W and 5W. I think you will find that most new stock 5881 beam power tubes are identical to the 6L6GC offering. So probably not much difference.

I know that in the 6V6 I much prefer the JJ to the EH tubes. I have JJ 6L6GC but have never tried the EH 5881 or 6L6 tubes. I had a bad experience with some EH signal tubes that kind of tainted my view of EH. My guess is that they'll be a little different, but as to better or worse, only a try out will tell you that.


That all sounds good and all grist for the mill with amp # 2. The sockets are a bit dodgy on the first amp I built so I'm not rolling anything. Received the Mundorf Supreme Silver and Oil caps a day ago and are half way through the external AC PS. So not far off now until amp #2 is complete. I'm getting excited.

Author:  mwhouston [ 28 Jan 2017, 05:51 ]
Post subject:  Re: SE 6L6 power amp, 12AT7 driver (design by Suncalc)

Al this for just 2W. 2 X 160VAC trannies to provide 12VAC and 250VAC. Also the underside of the new amp. Inter-stage caps are Mundorf Supreme Silver and Oil.
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Author:  mwhouston [ 29 Jan 2017, 06:08 ]
Post subject:  Re: SE 6L6 power amp, 12AT7 driver (design by Suncalc)

Amp two is up and going. The grey box holds 320VAC of tranni to provide 12AVC and 240VAC. There is over 800uF of filtering caps to provide 300V of HT. The XLR leads bring the AC voltages to the amp.
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Author:  mwhouston [ 29 Jan 2017, 17:17 ]
Post subject:  Re: SE 6L6 power amp, 12AT7 driver (design by Suncalc)

Some images of the back and under the bonnet. All solid core hookup wire and no shielded wire. You can see the Mundorf Supreme Silver and Oil caps.
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Author:  mwhouston [ 01 Feb 2017, 22:08 ]
Post subject:  Re: SE 6L6 power amp, 12AT7 driver (design by Suncalc)

Amp finally fully completed. Now with name plate - "Silver Supreme" named after the inter-stage caps. The amp continues to impress getting better each day.
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Author:  mwhouston [ 03 Feb 2017, 19:41 ]
Post subject:  Re: SE 6L6 power amp, 12AT7 driver (design by Suncalc)

Surprise, surprise surprise - I didn't realise until yesterday that the JJ 6L6s are "GC"s. That means they are the high power rugged version of the 6L6. Should I build yet another version of this great sounding amp I would use 20W OPTs and use Matt's original design which squeezed a little more power out of the amp. Apart from that I wouldn't change a thing.

Author:  mwhouston [ 07 Feb 2017, 18:29 ]
Post subject:  Re: SE 6L6 power amp, 12AT7 driver (design by Suncalc)

I happen to have a date matched pair of Sovtek 5881s with little to no hours on them. They are ruggedized versions of 6L6s. As 6L6GC are ruggedized version of 6L6s. They both are able to handle more power and often end up in guitar amps.
 
I never liked these tubes when I heard them in a push-pull amp but currently they sound better in my SE UL wine box amp "Silver Supreme". They need 50 hors to burn in and Ill make a decision then to swap back the JJ 6L6GCs or leave them in. The JJ are much prettier, face the right way and glow loudly.  Cant see these fellows lasting in unless they are much better sounding. No adjustments need to swap these in and out.

Also I stated from the start I felt this amp a little dark. Strong bass and lower midrange. I have attenuators on the tweeter and now have lifted the treble by 3db. Much better and still retails that lower mid-range weight.

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