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 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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PostPosted: 01 Aug 2010, 06:59 
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Feman: I think if you get the primary right for 8ohms it is case of try it and see if different speaker characteristics work with the amp. I will be using 2.5K 25W Edcors.

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PostPosted: 01 Aug 2010, 07:24 
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Thanks
Of moment, I will make a prototype
with solid PSU (have a power trafo also 200mA) to see if you feel fatigue in the out trafos

All the best
Fernan


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PostPosted: 01 Aug 2010, 11:02 
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Fernan;

Let me put your mind at ease. Anything I post here is free to anyone who would like to use it. You don't need my permission to use anything I post on this forum. :thumbsup: You are correct that I recommend the 25W Edcor output transformers because of the level of bias current in this design. You could try the 15W Edcors but I don't know how they will respond.

Does anyone on the forum have any experience using the Edcore 15W GSXE transformers at high bias current (~100mA)? My concern is that the bias current might be so high that magnetic core saturation may become a problem with the smaller transformers. If any body has any experience with this please let me know.

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PostPosted: 01 Aug 2010, 11:35 
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THANKS Matt

If it is true that I will play with the James 20W with 5K (218 ohm DC) primary but deceiving the secondary connection, for to obtain these 2K5 :geek:
Also has takes 2K5, so I will have to prove that it is better ;)

I comment on everything that pass the prototype before moving to the final mounting :horseshoe:

All the best
Fernan

P.S. Escusas by translattion


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PostPosted: 01 Aug 2010, 16:58 
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Ecor state their 15W OPTs are good for 65mA. On my KT120 amp I was passing 112mA through them. The sound was OK (bass a little compressed maybe) and they did not appear to get hot or anything. If you were looking to save dollars or did not have the room to use use a larger OPT I would say the 15W open Edcors will do the job. But the 25W will do it better.

In all my lower current tube amps (63mA) I have found the cheaper Edcors do an excellent job for the price.

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PostPosted: 01 Aug 2010, 17:21 
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Mwhouston, please see the Edcor Primary Bias Current Limit Table I just posted in the SET - Single Ended Tube Amps thread. If Edcor is generically stating that their 15W output transformers are rated for 65mA, then I think it safe to assume that the cores are gapped specifically for each power level and primary impedance. (With 10% power and bias margins, the XSE15-xx-10k number comes out to be 63.2 mA)

I am hoping that this should mean that the table I posted should be a good design guide for their SE transformers. I guess I should do a little experimenting to see if I can confirm my calculations.

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PostPosted: 13 Aug 2010, 19:33 
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This thread has gone cold. I'm waiting for a power tranni from Edcor. There was some confusion with PayPal but all sorted now. I would expect the tranni in the next few weeks. I have a base already to go and the OPTS(Edcor 25W).

This will be the next amp I build then back to some more 6AS7 SETs.

One 6AS7 SET I have mind is: retro-thermionic Pinot "Shin". This will feature a similar build to my first but Russian PIO caps and a di-cast Al chassis. Maybe SS rec. It may be very distinctive looking if I alter the chassis as I think I can. Stay tuned.

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PostPosted: 20 Aug 2010, 19:05 
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This thread will probably follow the same line as the "6AS7 tube amp from layout to listening" thread. Where I hope to make entries all along the way to show the amp from inception to completion. As I mentioned above the thread has gone cold beause of a delay in obtaining some parts (still intransit). Therefore no recent comments.

Anywho while still waiting for the tranni I have collected some of the minor parts required and hope today to do some work on the amp. Hope to have some comments and snaps a little later. I am busting to get this amp underway but without main parts its a little hard.

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PostPosted: 21 Aug 2010, 07:02 
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TOO beautiful to be true! :eek:
My prototype was going to work on a table in an hour and a PE06/40N Brown base... my wife has approached and plofffffff! :tombstone:
still not I reacted :mad:
for the 2 PE06/40E black base, I have no sockets :evil:

I don't know, if repayable desire to continue then with common 807s or Russian (neither has the beauty of the PE06/40N Brown base)


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PostPosted: 21 Aug 2010, 08:30 
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Got some early snaps

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