AUDIO BUDDY preamp problem-any idea?

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maxkriza

Well-known member
Joined
Sep 18, 2004
Messages
68
Location
uk
Hi
I'm having some annoying oscilation on this cheapo mic preamp which I try to troubleshoot . the main one is at about 7.5Khz @ -50db , some lower ones at 12.7khz and 15khz . noise level is -90db . they are identical on both channels . will appriciate any idea .
thanks
MAX
 
...since 15k is a multiple of 7.5k, I'm wondering if it's a switching power problem... like a noisy multiplier for a 48V phantom or something similar.

I know the audiobuddy is a cheap design; Guitar Center had a mega-sale on them a while ago, you got an MXL mic for $30 and they GAVE you an audiobuddy to go with it for free... that's less than the list on the AudioBuddy... none the less, it means that the profit margin is high.

Without a schematic this is all just blind guesswork, but my forst blind guess is switching noise from a dodgy DC-DC conversion.

Keith
 
thanks
the supply is 9V AC external and the oscilation persists regardless of phanton being on or off . I looked for a schematic and couldn't find one .
 
Switching the phantom off would likely not stop any DC-DC converter. 9VAC could mean a dual-multiplier at 120Hz for the ±V to drive it, and conceivably also the phantom rail, but unless there's a schematic, this is all a blind guess.

Keith
 
[quote author="maxkriza"]Hi
I'm having some annoying oscilation on this cheapo mic preamp which I try to troubleshoot . the main one is at about 7.5Khz @ -50db , some lower ones at 12.7khz and 15khz . noise level is -90db . they are identical on both channels . will appriciate any idea .
thanks
MAX[/quote]

Take a photo of the top and bottom of the board and we can probably help you.
 
the audio buddy is digital out isn't it?

ssl9k frontend with the a/d converter from the audio buddy for output sounds like a plan to me...
 
[quote author="Svart"]the audio buddy is digital out isn't it?
[/quote]

Digital out, where? I will cease using it as a doorstop then. Actually it is the cheapest possible preamp using a few opamps. I bought it for $30 new. It is worth nothing though. It distorts at all levels and the mids are scooped out badly. Another use might be as an ashtray.
 
No, the AB doesn't have a digital out. It doesn't even provide proper P48. Measure the phantom under load sometime and see...

I was given one as a gift a few years ago. I'm not real impressed with it. I guess it's OK as a utility device if you need a couple of preamps on a low-fi job, but I wouldn't use it for serious recording.
 
oh my bad, I must be thinking of something else! :oops:

I found that you can build a pair of ssl9k pres for less than 100$ in parts not counting the chassis and frontpanel work...
 
I found a pile of those while diving in Lake Almanor last summer. Right next to a stack of accordians.

Can you scrap that thing for any usable parts or sheetmetal?
 
[quote author="NewYorkDave"]No, the AB doesn't have a digital out. It doesn't even provide proper P48. Measure the phantom under load sometime and see...

I was given one as a gift a few years ago. I'm not real impressed with it. I guess it's OK as a utility device if you need a couple of preamps on a low-fi job, but I wouldn't use it for serious recording.[/quote]

Yeah, I also have it and have to agree--the stock one is far from a serious pre, maybe on a par or little better than B*ringer compact mixer. I changed however the signal electrolytics for film 5mf caps and sound improved dramatically... really. The phantom problem is still there, though. I keep this puppy as a back-up.
 
I'll send someone pics of the board if they want to host them. I've still never figured out how to post pics on a forum.....
 
Hey Max.

If you still haven't solved your problem, you can adress me via e-mail, and I can help you with a schematic and further help if you have any problems.

My e-mail is al_si (at) netvision (dot) net (dot) il
 

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