The BA-3 as preamp build guide

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Russellc

Member
Joined 2003
Paid Member
Yes, I guess I only lost the mosfets, playing fine now. So glad Jfets survived!
This pre will drive the F6....hopefully chassis available soon. It has the 10mm faceplate and extensions on the controls. Used the Tube cad preamp 6L6 suggested this time, otherwise its just like my previous BA-3 FE build.

I did learn something this time, like Andrew suggested it is just a good protocol to do first fire up with the dimbulb setup. It likely would have saved my mosfets.

Was using a variac, that and the fact this is the third one I've done, I just got a little over confident, little too tired and made a silly mistake. Really silly. All is well now.

Russellc
 
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Russellc

Member
Joined 2003
Paid Member
Its burning in nicely in my downstairs system, which uses the F-5. The BA-3 FE replaced what was a nice sounding B-1. I normally dont care for B-1 with F-5, but my downstairs speakers are big Econowaves, very efficient and the B-1 shines with the F-5 on these....well, until I put the BA-3 FE in its place....

The BA-3 FE is a really nice sounding preamp. Very pleased with this unit.

Russellc
 
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didiet78

Member
Joined 2007
wengtech said:
Ah... I see... its look like I have wrote a confusing sentence here.
When I say no caps at all, its mean no caps at the input or output preamp.
Of course at the servos and preamp PSUs still using the some filter caps.

I will post the pictures later.

Peace.
Click to expand...

If your servo use ATP schematic, Biju55 already post link. It still use Cap (1uF) on feedback loop of opamp and integrator.
 
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nashbap

Member
Joined 2012
Zen Mod said:
1. if matched , better

2. grade B is , unfortunately, what you need for BA3 , with possible lower range grade C

3. matching preferred
Click to expand...

In the BA3 article Mr. Pass says "matching is nice, but not essential. P1-3 will cover much of that action"

Is the reference to matching being made between the 2SJ313 and 2SK2013 Fets of each channel or to the 2SJ313 for the left and right channels and the 2SK2013 again for left and right or to all four of them?

Thanks. Nash
 
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fwt1712

Member
Joined 2012
I am after some advice regarding the appropriate transformer for a ps-19 power supply (+/-24v). My issue is that 20v transformers are not readily available in Australia. I can get 18v or 22v easily - would one make sense than the other. Line voltage here is 240v so I am thinking that a 230v primary 18v secondary transformer should give me just over 24v, taking into account the extra line voltage (240/230), rectification (*1.4) and regulator losses (-1.5). Thanks Nigel.
 
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