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Old 28th October 2011, 11:32 PM   #321
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Hi,

Nice album and moreover, a very touching war story.

Thanks to Deborah Right from the Thatched Cottage in Bishop's Stortford for educating me...

Carry on and ignore me, just don't you ignore the power of the OTL.

Cheers,

small world..........
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Old 29th October 2011, 09:04 AM   #322
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by atmasphere View Post
Just FWIW- over the years I've seen many of those with leakage problems... IMO its the worst 6SN7 ever made. If you are on a budget try the Chinese 6SN7, it sounds better and is a lot more reliable.
Well yes you are correct,

I have the replacement tube for the original 6H8C.

The sound is way better. So their you go. Tung Sol's on order.

Regards
M. Gregg
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Old 29th October 2011, 09:52 AM   #323
M Gregg is offline M Gregg  United Kingdom
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Spell for today!

Tout, Tout, through and about; your callow life in dismay. Rentum, Osculum, Tormentum:

Build an OTL today.. Murphy’s Law !



Film: Warlock (1989)

Happy Halloween!

Regards
M. Gregg
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Old 29th October 2011, 03:39 PM   #324
M Gregg is offline M Gregg  United Kingdom
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Must stop posting.

Last one!

6Hrs again ....

Al DiMeola Electric Rendezvous

Al DiMeola - Cruisin' - YouTube

http://www.youtube.com/watch?v=np3Qr...feature=fvwrel

Regards

M. Gregg
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Old 30th October 2011, 03:14 PM   #325
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Sounds like you're enjoying it M-Gregg....

I'm still messing round, Ive made up some 'CCS' (MOSFET Anode-Load boards), but as the volts from them is approx 1/2 +B to allow the best op-point of the SN7 before the phase-splitter, I must use a pot. divider or modify the P.I. for self-bias, to keep the P.I. bias point right.....

I prefer the pot. divider idea,--two caps in the gain-stage is quite enough IMHO! although this will lower the loop-gain by a few dB....

--Hey M-Gregg, We may have a use for those 6SL7 you have after all!
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Old 30th October 2011, 08:44 PM   #326
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Well, Ive done this last modification.

Ive now got MOSFET loaded second gain stage, with a pot. divider to maintain correct bias for the P.I. as its still DC coupled.

First impressions, sound is a tad 'richer' and bass appears to extend further down,--less 'cramped'...

Clarity is superb, and there doesnt appear to be much in the way of lost gain, probably due to the action of the 'Mu stage', the effective amplification-factor is now closer to the theoretical max of 20 for the SN7, whats lost in the pot. divider is sorta partially compensated for.

Much more listening before I decide whether this mod is worth it, but first impressions are good....
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Old 30th October 2011, 11:19 PM   #327
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by Alastair E View Post
Well, Ive done this last modification.

Ive now got MOSFET loaded second gain stage, with a pot. divider to maintain correct bias for the P.I. as its still DC coupled.

First impressions, sound is a tad 'richer' and bass appears to extend further down,--less 'cramped'...

Clarity is superb, and there doesnt appear to be much in the way of lost gain, probably due to the action of the 'Mu stage', the effective amplification-factor is now closer to the theoretical max of 20 for the SN7, whats lost in the pot. divider is sorta partially compensated for.

Much more listening before I decide whether this mod is worth it, but first impressions are good....
Should be interesting!

......

Regards
M. Gregg
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Old 31st October 2011, 07:21 PM   #328
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Quote:
Originally Posted by M Gregg View Post
Well yes you are correct,

I have the replacement tube for the original 6H8C.

The sound is way better. So their you go. Tung Sol's on order.

Regards
M. Gregg
You want to watch it with **any** of the Russian-made 6SN7s. So far the Tung Sols have shown a lot of leakage, although they sound OK if leakage is not a problem in your amp (meaning that you have regulated DC supplies for the 6SN7 filaments...).

The vintage Russian 6SN7s are another matter- by 'vintage' meaning 1970s or earlier. They can be excellent.
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Old 31st October 2011, 09:12 PM   #329
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by atmasphere View Post
You want to watch it with **any** of the Russian-made 6SN7s. So far the Tung Sols have shown a lot of leakage, although they sound OK if leakage is not a problem in your amp (meaning that you have regulated DC supplies for the 6SN7 filaments...).

The vintage Russian 6SN7s are another matter- by 'vintage' meaning 1970s or earlier. They can be excellent.
Thank's for the information,

I have regulated supplies for heaters on the input 6SN7's.
I have a vintage (NOS) Brimar in the phase splitter (AC Heater).
The ones I am using on the input at the moment are 1960's russian.

What do you regard as the "Best" 6SN7?

Regards
M. Gregg
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Old 31st October 2011, 09:12 PM   #330
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Perhaps I was just lucky with my 'fake' tung-sol tubes....

They perform flawlessly and have no leaks...
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