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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

ultra linear PP 6v6 kit (dynaco A-410)

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Eli Duttman

Member
Joined 2004
I don't like it. The "finals" are UL mode and the 6SL7 is high RP/low gm, which is (IMO) not a good idea for driving the CMiller that is present. The 6SL7 rates to be OK with full pentode mode "finals", with their tiny CMiller.

BTW, the paraphase small signal setup is unimpressive.
 
Lingwendil

Lingwendil

Member
Joined 2008
I picked up one of these PCBs a while back, I cut some traces to convert the front end to a concertina, and plan to go for a separate screen supply on the outputs.

I think the price is reasonable, but I wouldn't recommend buying it as it unless you plan to modify it.
 
M

mctavish

Member
Joined 2008
I have one that is similar... It is a good starting piont, but needs some mods.

It was just for fun, but its certainly not a bad starting point.

I dont have anything against a paraphase splitter, some Magnavox examples I have sound quite good. Is it the pinnacle of HiFi?

No, but tubes wouldnt be the direction I would go if ulitmate fidelity was the end goal anyway....
 
TheGimp

TheGimp

Member
Joined 2009
Switch the 6SL7 to a 6SN7, and change the bias resistor and plate resistors. You will need 3x the drive that way, but if you have a line amp you can drive it. Otherwise reduce the GNFB.

Might be something fun to play with, but as pointed out it needs modification.
 
Mr_Zenith

Mr_Zenith

Member
Joined 2009
The amp linked by the OP is yet another incarnation of the old Acrosound circuit (see page 9)* - which in turn spawned the one in this article. That AX amp was my first DIY scratch build, but I didn't make the connection until years later. It sounded pretty good (no doubt due in large part to the Heathkit AA-151 transformers), but the DC heaters and bypass switch were utter overkill.


*For some reason the forum software is altering my hyperlink to the Acrosound catalog noted above. It can be found at: www.tubebooks.org/file_downloads/acrosound.pdf.
 
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45

45

Member
Joined 2008
huggygood said:
I think I will mount it like this to get an idea and depending on the result, I will change it or not if it suits me.
i really like 6v6 :)
Click to expand...

I agree. I would not change anything. Although it could be better it is not bad as someone says. The Miller capacitance of the 6V6 with 43% UL is about 60 pF and each half of 6SL7 should work at about 0.9 mA. I can't see a problem, surely up to 25-30 KHz where the Hammond starts to give up.....
The paraphase is a better performing input/splitter stage than SE+concertina with tubes like the 6V6 and 6L6 in my experience despite its non-symmetrical look.

This amp will make a surprisingly good match with loudspeakers like the TABAQ.
 
2

2stuffed

Member
Joined 2016
I made this amp .I used BEZ opts and Fivre 6V6 and Adzam 6SL7s. It sounds good to me with Karlsonator 8 and 12.
 

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