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dynacord BA300

#42
The ECC 81 is used as the phase inverter and its driver stage in all designs using that modular concept, i.e. starting from the 1966 Bassking/Eminent up to the latest member of that family, Your BA-300. The ECC 808 is used in those stages where the signals are small. In between the (cheaper) ECC83 had been used. In later designs, all functionality before the phase inverter stage had been implemented with transistors.

BTW: thanks for the PM.

Beate
 
#45
It's HERE>>>>>> YEAH!!

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ANd it sounds great... It came with new tubes. One tube missing. But he gave me that as an extra. So 4 new end tubes...

He said after repair he still had issues. I think it's the standby switch... Well. I could play without any trouble. And it's dead quiet. Allways a good sign... Tomorrow more. It's 1 in the morning and I drove 4 hours to get it... I'm done..
 
#46
Hmm. Yesterdaynight it played fine. Tho I didn't play loud. Today I had some time with it. The former owner informed me that the preamp oscillated. And Now I found that it sounds grainy... So there is something in the preamp section that needs work...
 
#49
Yeah. As a chassis, this is beautifully made...

I think my capacitors (the silver big round things in their own little space, just below the output transformer) need to be replaced. Cause often the sound is alil worse. JUst like when you turn off an amp but still play some notes and then you hear the sound getting worse... sorta crispy...

Gonna change these out and see how that works out.
 
#53
Muziekschuur said:
I think my capacitors (the silver big round things in their own little space, just below the output transformer) need to be replaced.
Click to expand...

A good source may be jan Wüstens (http://www.askjanfirst.de/) - he has the tright replacement parts on stock. I bought mine from there.

you should increase the screen grid resistors to 1.2 kOhm - recent el43 are less capable as early ones - and this power section goes to the absolute limits of the tubes.

you should also bridge the bias potis by some 40 kOhms. in the original circuitry a failure of such a poti (well known problem of all these amps by dynacord) will destroy the tubes and maybe the output transformer.

Here You find technical information on these amps: Invalid Link Removed - Gigant, B1001 and G2000 have nearly the same output section. The plans include voltage values - everything from DC, biasing and signal. You should take care not to overload the tubes while biasing - because of the high anode voltage the tolerances are not too large.

And if You can read german, You might have a look here: Invalid Link Removed
 

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