Hello All
I have a Sugden A28 II amp. (external heat sink on the back). I know nothing about amplifiers. I bought it new about 30 odd years ago. I really like the amp, but it has some issues. I was hoping to get some insight/advice from the learned members.
Problems:
1) When I turn the amp on, I get a loud "whooomp" sound from the speakers. (Vandersteen 3C signatures, if that matters) Am I damaging my speakers? What can i do to eliminate that sound???
2) I get a crackling noise as i turn the volume knob.....only while moving the knob.
3) Turn the selector knob to aux (where I have the CD player) CD player off. Tuner on......turn up volume...you can faintly hear the tuner. Not a problem, just wondering if that indicates an issue that should be fixed.
4) At thirty plus years old, should I replace anything in the amp while I have it into the shop to address the above issues? ( i have been reading people in the forum who talk about replacing capacitors and such)
Any advice/insight most appreciated. I want to have some idea what i am talking about when I take the unit in for repair.
Thanks in advance!!!
Darren
I have a Sugden A28 II amp. (external heat sink on the back). I know nothing about amplifiers. I bought it new about 30 odd years ago. I really like the amp, but it has some issues. I was hoping to get some insight/advice from the learned members.
Problems:
1) When I turn the amp on, I get a loud "whooomp" sound from the speakers. (Vandersteen 3C signatures, if that matters) Am I damaging my speakers? What can i do to eliminate that sound???
2) I get a crackling noise as i turn the volume knob.....only while moving the knob.
3) Turn the selector knob to aux (where I have the CD player) CD player off. Tuner on......turn up volume...you can faintly hear the tuner. Not a problem, just wondering if that indicates an issue that should be fixed.
4) At thirty plus years old, should I replace anything in the amp while I have it into the shop to address the above issues? ( i have been reading people in the forum who talk about replacing capacitors and such)
Any advice/insight most appreciated. I want to have some idea what i am talking about when I take the unit in for repair.
Thanks in advance!!!
Darren
For sure, disconnect the speakers now, and only reconnect them after it is fixed.
The shop repair will be plenty expensive enough without any improvements.
Probably they will replace a bunch of bad electrolytic capacitors, and a general cleaning of controls.
Get an estimate, and then consider whether it's time to put it out to pasture.
The shop repair will be plenty expensive enough without any improvements.
Probably they will replace a bunch of bad electrolytic capacitors, and a general cleaning of controls.
Get an estimate, and then consider whether it's time to put it out to pasture.
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It is single-supply all the way through. It is sure to WHOOOMP at turn-on. There is a disconnect relay to the speaker but I *think* this is to mute the turn-OFF thump (so maybe it is worse, except muted).
I would however beware using any small/soft-woofer loudspeakers unless I could see how far the cones are moving at turn-on. Many old speakers were hefty and stiff, were not troubled by turn-on thump.
Old pots scratch. Normal.
Simple selector switches WILL bleed unselected inputs. Basic physics. D.Self has several advanced switching systems to reduce bleed-over. The usual no-cost "fix" was to turn-off unused tuners, CDs, TVs, etc.
Those Vandersteens are eXpensive?? I would seriously consider a fresher more-polite amplifier just to protect the speaker investment.
I would however beware using any small/soft-woofer loudspeakers unless I could see how far the cones are moving at turn-on. Many old speakers were hefty and stiff, were not troubled by turn-on thump.
Old pots scratch. Normal.
Simple selector switches WILL bleed unselected inputs. Basic physics. D.Self has several advanced switching systems to reduce bleed-over. The usual no-cost "fix" was to turn-off unused tuners, CDs, TVs, etc.
Those Vandersteens are eXpensive?? I would seriously consider a fresher more-polite amplifier just to protect the speaker investment.
Going by symptoms 1) and 2), it sounds like the amp could use a recapping. The coupling cap at the volume pot is likely to be leaky, and more of them may be dried out, throwing off the time constants that would be keeping the amp from emitting too much of a turn-on thump. If there is a relay I would imagine that the turn-on delay has gone to zero.
The 100µ/35V would be my #1 suspect. The triac (2N5062) might also be shorted.
Just let us know if you need help picking replacement caps. I hope this amp isn't full of axials.
The 100µ/35V would be my #1 suspect. The triac (2N5062) might also be shorted.
Just let us know if you need help picking replacement caps. I hope this amp isn't full of axials.
Attachments
Thank you very much to everyone that has replied!. I especially appreciate the detailed answers which call out specific things to try. The local audio repair guy states that he doesn't do "repairs" but rather "restorations" I assume that means a more in depth look at all the components and then changing out and tuning things. If that is the case, are there certain brands of capacitors or transistors etc that I should be asking him to use in the restoration ?
Thanks again for everything....very much appreciated
Darren
Thanks again for everything....very much appreciated
Darren
Make sure that he promises the problems will be fixed during the work.
And get a firm price quote first.
And get a firm price quote first.
Agreed, restoration rather than repair usually means a clean-up of dust and grime inside and out, with a thorough program of replacements of suspect and failed parts and fittings such as terminals, feet and perhaps damaged knobs and controls, power lead. lamps etc. Then there's electronic repairs, full load testing, soak test and adjustments as required. Often, sourcing old parts is a long and fruitless quest so substitutions have to be made with modifications where genuine, original components are no longer available. This should always be negotiated because it amounts to a design change.
In other words, it's very likely going to be expensive - more than the price of a similar used amp in good condition, I'd suggest.
In other words, it's very likely going to be expensive - more than the price of a similar used amp in good condition, I'd suggest.
Does anyone know a person located in Ontario Canada that will repair this unit? I have contacted a couple people and they say they are not interested in repairing Sugdens....(?)
Any leads would be appreciated.
D
Any leads would be appreciated.
D
Hi,
I owned the same Amp, sold it 1 year ago.
Before, I replace all electrolytic caps, 30 year old !
Read carefully previous caps specs (ESR/RDS), voltage, pitch, height,...
Another point to take care concerns the PCB itself, very thin tracks that could be damaged by overheating.
Alps pot need some magical flux and back to work silently, no more crackles.
Front source selector squared buttons are pushing onboard switches.
Those switches need some "grease", they are heat sensible too 🙂
There's a thread dedicated here :
Sugden P28
Maybe you'll find some help there.
Cheers
I owned the same Amp, sold it 1 year ago.
Before, I replace all electrolytic caps, 30 year old !
Read carefully previous caps specs (ESR/RDS), voltage, pitch, height,...
Another point to take care concerns the PCB itself, very thin tracks that could be damaged by overheating.
Alps pot need some magical flux and back to work silently, no more crackles.
Front source selector squared buttons are pushing onboard switches.
Those switches need some "grease", they are heat sensible too 🙂
There's a thread dedicated here :
Sugden P28
Maybe you'll find some help there.
Cheers