2. amps-preamps
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Why is my Audio Research SP6-b noisy?

I have an Audio Research SP6b pre-amp and it is very noisy-has a very loud hiss.I do have it hooked to a very large
pair of altec lansing VOT horn loaded speakers.I have used
4-5 amps and it stills has the hiss.Is this normal?
I know the horns amplify the hiss because when I hooked it
up to my klipsch speakers it was not as noticable.
Any suggestions.I just replaced the tubes.It does it with
the new tubes and old tubes.Go figure.
Anyone else have this problem?
89vett
128x12889vett
bob_bundus
1,834 posts
 
vett this is my typical experince with tubes + horns, which are very sensitive. The only tube preamp that I found quiet enough was a Golden Tube SEP-2 or SEP-3. All the others that I tried were so noisy & microphonic (including some very pricey & popular preamps) that I "just said no" to tubes. Try some quality solid state instead.
89vett's avatar
89vett OP
32 posts
 
Thank's for the responses.I have new tubes in it and no
difference.The unit does sound incredible though.I
will talk to Audio Research.
Steve
newbee
4,767 posts
 
steve, do i assume correctly that you first noticed the hiss when you started using the horn speakers? if that is so, then you are the victim of their efficiency. i've noticed the same thing with an sp10 which is very sensitive to tube noise. one way to solve the problem is to attenuate the output of the preamp. for example in order to get remote control, i inserted a passive volume control (think placette or crook) and this did the job quite nicely. there are probably other ways of attenuating the output of the preamp but i'm not a technician and can't help you.
rbrandon82e8
1 posts
 
Output caps in both the phono and pre-amp stages can cause noise.
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