New supply for Hood amp.

[john & Jake]

hi,
after sending an old modified Exposure regulator board from the VIII to Andy Weekes for his amusement, I received it back at the weekend.
Andy had transformed it.
Now it was spotless, like new, and had been completely redesigned.

He had modified it to regulate my Hood preamp and a couple of connections later it was making music like the Hood had not seen before, an improvement out of all proportion.

I've certainly got the message that supply is so important in amps.

 

[RichardH]

Interesting. As you know John, I'm currently building a Hood headamp, so will follow this with interest.

R

 

[Andrew L Weekes]

John,

Post a pic, by all means.

For those interested John sent me an old Exposure regulator PCB - this would have originally been in an Exposure power amp, powered by a seperate winding (or seperate TX in some cases, IIRC) and provided +/-24V to an Exposure preamp.

The board was, to be polite, a bit 'messy'

It had been severely hacked and modded, so I simply stripped it bare, keeping the regulators for testing, and cleaned the PCB.

It was then rebuilt using the existing reg's, which were fine, adding some choice components and set for +/-12V for the Chiara Hood amp.

The LM317 / 337 provide a much better supply than the existing 7812 / 7912 devices, as John is now finding out.

Wish I'd have take a before pic, it would be unrecognisable!

Andy.

 

[john & Jake]

hi,
pic now posted above.

 

[RichardH]

John, before you got that new board in, and were running the "stock" supply with the 12V regs, did you find they were getting fairly hot? And were they running hotter than the 15v regs (I'd imagine they must have been).

I'm wondering whether I should put bigger heatsinks on them....

 

[john & Jake]

hi Richard,
Yes the 12v regs that Andy supplied ran very hot to the touch.
I asked Andy at the time if this was ok, and he said they would run hotter as they had more energy to dissipate, but were ok.

A bigger sink would do no harm though and probably be good for reliability.

how's it sounding?

 

[RichardH]

That's what I thought re heat - they've got to lose another 3v after all.
Sounding good, though only run it from a portable CDP at the mo, as it's still "on the bench". Think I'll try some different sinks at some point, anyway.