Home » Audio » Thermionic Emissions » It's alive.....Alive!!!!
It's alive.....Alive!!!! [message #9255] Sat, 08 October 2005 16:48 Go to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
Hey-Hey!!!,
I got the 1:1 linestage up and running. AC to the 5687's heater no less. While waiting for Mouser to deliver parts for the DC supply( 60,000 uF of Low-Z caps, Schottky diodes and somemisc bits for the rest ), I hooked it up.

The buffer is a hybrid cascode with IRF820 MOSFET's and a section of 5687 running at 15 mA. This faux pentode has some seriously flat "plate" lines, so I went with a single stage of B+ filtering.

Output is through a 1:1 80% Nickel TX by Intact Audio. .004" gap for 15Hy of primary L.

I ran a $2.99 RadioShack Alps pot for the volume control. It sounds quite good. The low gain removes the principle complaint with those cheap pots: tracking mismatch.

Compared to the previous active design( with gain ), this one is a bit cleaner. Slightly less euphonic perhaps. The active loaded 12B4 is not very colourful tube, and that's part of the reason I like it so much. The buffer circuit is a step cleaner. How much from the cascode buffer circuit, how much from the high perm, bifilar output TX's?

I have got to say I am pleased with it. If not for the Nickel outputs, this would be quite inexpensive. No DC filament requirement, single stage L-C filter for B+. It is quiet...on AC no less. That one was a very pleasant suprise. The 6754 allows a full warm up of the 5687 before bringing on the B+ slowly enough to make a damper diode jealous.
cheers,
Douglas

Re: It's alive.....Alive!!!! [message #9256 is a reply to message #9255] Sat, 08 October 2005 17:23 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

Sweet!


Re: It's alive.....Alive!!!! [message #62247 is a reply to message #9255] Thu, 01 April 2010 15:48 Go to previous message
lord is currently offline  lord
Messages: 4
Registered: April 2010
Esquire
Hello, I also do a hybrid amplifier, works great, even better than usual!
http://tehnic.ucoz.ru/publ/gibridnyj_unch_luchshee_ot_lamp_i_tranzismtorov/1-1-0-7
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