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Old 27th September 2005, 07:15 PM   #1
mirland is offline mirland  Denmark
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Default Autocostruire t-amp hiss ?

Hello!

I've just built an integrated amplifier using this kit:
http://www.autocostruire.com/catalog...roducts_id=258

When finished I also built a pair of high effeciency fullrange speakers (Audio Nirvana). But when connected the amp (not the source, a Rega Planet 2000) - or I believe it's the amp - generates a very loud hiss. I've tried changing amps (Onix and Naim) and while they also generate some hiss it's not as loud as the t-amp.

I don't know much about these things but I really want to find a solution.

Any advise and help is appreciated !

/Mirland
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Old 27th September 2005, 10:29 PM   #2
Nuuk is offline Nuuk  United Kingdom
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OK, if it's the 2020-m amp that you have built, it does have quite a high gain. This would be consistent with it producing more hiss than the other amps and that may indicate that the hiss is eminating from somewhere before the power amp stage.

Can you tell us exactly what you have in the 'chain' form source to speakers?
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Old 28th September 2005, 04:49 AM   #3
mirland is offline mirland  Denmark
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Sorry for the late answer. Had to catch some sleep

My chain is:

Target stand -> Rega Planet 2000 -> Rega Couple interconnect -> t-amp w. external regulated 13.5W/5A psu -> Supra speaker cables -> Audio Nirvana 8" / 8ohm / 96db / 18L fullrange bassreflex internal wiring Supra Ply 3.6 speakers on Audiomagic stands.

/Mirland
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Old 28th September 2005, 08:07 AM   #4
Nuuk is offline Nuuk  United Kingdom
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OK, you tried different amps but the hiss was still there so do you have another source that you connect in place of the Rega Planet?
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Old 28th September 2005, 08:34 AM   #5
mirland is offline mirland  Denmark
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I've tried disconnecting the Planet with no difference... I know the preamp-part often is a bit noisy in the upper areas but this is too much. Last night I connected my Royd Saphires instead of the fullrange speakers. There is still a hiss but much much less audible. Is it possible that the high effeciency is revealing too much ?

I haven't tried using a SMPS yet as I still need a cabinet for it. Might that make a difference ?

/Mirland
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Old 28th September 2005, 08:40 AM   #6
Nuuk is offline Nuuk  United Kingdom
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Quote:
I know the preamp-part often is a bit noisy in the upper areas but this is too much
What pre-amp? You said that the Rega Planet was connected to the t-amp!
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Old 28th September 2005, 08:44 AM   #7
mirland is offline mirland  Denmark
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Quote:
Originally posted by Nuuk


What pre-amp? You said that the Rega Planet was connected to the t-amp!
My bad ! I was referring to the preamp section of traditional integrateds

/Mirland
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Old 28th September 2005, 08:50 AM   #8
Nuuk is offline Nuuk  United Kingdom
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OK. Well as you state, having more efficient speakers is more likely to expose hiss or hum but the point is there shouldn't be any there to expose in the first place.

I would still like to know if the hiss is there with a different source, not just with the Planet disconnected. If it is not the source, then you have to start looking at your interconnects!
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Old 28th September 2005, 09:00 AM   #9
mirland is offline mirland  Denmark
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OK ! I will connect my mp3 player tomorrow (I won't be home until late tonight) and see if it acts differently. But what you're saying is that there should be NO hiss whatsoever ?

I must say the only time I haven't had hiss was when I used an Acurus DIA-100 amplifier - and that one has no preamp stage but only a very effecient poweramp. Unfortunately I haven't got the Acurus anymore. But I have always had hiss when using either Onix or Naim no matter which speakers I used.

I find it rather hard to believe the source or the interconnect should be the problem ? How could they ?

Am I the only one with this problem ? Or am I too touchy ?

/Mirland
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Old 28th September 2005, 10:03 AM   #10
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Without hearing the level of hiss, I can't comment but I think that I would be like you, ie any hiss/hum is too much and we should take steps to get rid of it. So no, you ar enot being too fussy!

I had a (very) loud hum coming from an amp the other day. It was nothing more than a bad connection in one of the interconnects!
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