Slow blow preamp into La2a

[johnheath]

Hi

I've built a slow blow preamp without output transformer and the sound is great… quiet and full and rich.

But, with the unbalanced output it won't work with my la2a and if I add a output transformer (sower 8403x) it just sound thin and grainy and distorts very early when I turn pup the volume.

Can anybody give me some advice on how to maintain the good sound without the output transformer and still being able to connect the preamp to the la2a?

Thanks

/John

 

[johnheath]

Problem solved =)

 

[rafafredd]

Got curious. What was the problem, and how did you solved it? Tried a bigger output transformer?

 

[johnheath]

No… in fact it was really simple. I had to short the ring in the "balanced" output jack.

There was no good way to add the output transformer to this preamp…. it is really a killer preamp without the output transformer.

/John

 

[buildafriend]

sorry to bump an oldie but I'm building this currently and im curious if you used the 10uF cap at the output. Why is it so large? I normally see things like .22uF, .1uF or even 1uF or 2,2uF there. I thought that cap was more about just DC blocking and setting your cutoff frequency.

 

[rock soderstrom]

The 10uF  output  cap  is needed for a good bass response if you work  with old gear with low input  impedance, for instance to form a vocal recording chain with a  1176 compressor.  (only 600R!)

You can go for a smaller cap if you work with a stepdown transformer or into a static higher impedance input.

 

[buildafriend]

The 10uF  output  cap  is needed for a good bass response if you work  with old gear with low input  impedance, for instance to form a vocal recording chain with a  1176 compressor.  (only 600R!)

You can go for a smaller cap if you work with a stepdown transformer or into a static higher impedance input.

My only good real world compressor is a hairball mnats 1176 kit so ill need to assure that this works well for that but I also want it to be transformer balanced on the output ill experiment with the cap sizes in the prototype but ill want a usable op transformer. I first thought about trying an edcor 600 : 600 transformer since it worked great for me at the end if the MILA 1.