Just accepted delivery of this wonderful amp in pristine outer condition today. The inside needs a good clean and I also need to clean the POT along with other knobs, volume cracks worse than a crackhead wh0r3 hooked on crack.. 
Regarding the all important sound quality, well, had a brief listen... its not bad. Infact, its far better than anything I have head at this price range (second hand ebay bargain mind you).
Compared to my Audiolab 8000S + 8000P it seems a little "shouty" and lacks the openness. Bass is a bit of a shallow thud and lacks any grip, weight and authority. The mids and highs are ok, but it does sound a bit 'shouty' overall. Like a week, sick, hungry dog trying to bark out loud to defend his 'urine patch' (ok, a bad little exaggeration).
Anything I can do to improve the sound? Anyone familiar with this amp? Is it worth the effort?
Regarding the all important sound quality, well, had a brief listen... its not bad. Infact, its far better than anything I have head at this price range (second hand ebay bargain mind you).
Compared to my Audiolab 8000S + 8000P it seems a little "shouty" and lacks the openness. Bass is a bit of a shallow thud and lacks any grip, weight and authority. The mids and highs are ok, but it does sound a bit 'shouty' overall. Like a week, sick, hungry dog trying to bark out loud to defend his 'urine patch' (ok, a bad little exaggeration).
Anything I can do to improve the sound? Anyone familiar with this amp? Is it worth the effort?
This is some of the "junkiest" "vintage" gear you can find. I'm not surprised that you don't find it impressive. It's got a fundamental flaw - low budget unit with no passion or interest invested into it. Improving it would involve scrapping everything and starting over. I'd begin with that ugly case.
Or, actually, I'd get rid of it altogether.
I've had a slightly cheaper still Pioneer of that same era. It was a true killer of music.
Or, actually, I'd get rid of it altogether.
I've had a slightly cheaper still Pioneer of that same era. It was a true killer of music.
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Hi,
It is what it is. Can it be made better ? Yes. Is it worth the effort ? No.
Clean it up and use it for what it essentially is in a basic budget system.
My favourite very budget amplifier is the Pioneer A300X, ~ £50
from epray delivered which in stock form is a great budget amplifier,
and a real lump of very well built and finished amplifier for the money.
Miles better than a NAD3020 at double the price, and miles better
built to boot. It is a cheap high quality amplifier, can't go wrong.
rgds, sreten.
It is what it is. Can it be made better ? Yes. Is it worth the effort ? No.
Clean it up and use it for what it essentially is in a basic budget system.
My favourite very budget amplifier is the Pioneer A300X, ~ £50
from epray delivered which in stock form is a great budget amplifier,
and a real lump of very well built and finished amplifier for the money.
Miles better than a NAD3020 at double the price, and miles better
built to boot. It is a cheap high quality amplifier, can't go wrong.
rgds, sreten.
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For one thing, there's a bunch of 35-year-old switches, pots and small electrolytics in the signal path that are likely to require attention. Make sure you are only using contact cleaner that is safe to use on pots and such and doesn't corrode your components by itself. Check what's available where you live.
Looking at the schematic for the power amp, I would say that
1. the amp probably is a tad noisy and
2. the biasing arrangement kinda sucks.
Bias is fixed to facilitate manufacturing, and makes use of diodes only (I've never been able to get decent output stage biasing like that). Permitted voltage across the 0.22 ohm emitter resistors is given as 4 to 50 mV, which equates to a bias current of 1 to 12 mA. The output stage is moderately to severely underbiased like that. (Well-performing commercial amps would typically run 30-50 mA to keep temperature in check, the theoretical optimum would be about 100 mA.) Now they can claim a 0.03% THD at 20-20k all day long, but given a 4 ohm load the numbers probably won't look too grand... and the sound may not be either. The drivers are only getting 2 mA, too. Suckers aren't heatsinked either, grrr.
The rest of the power amp circuit looks like it should perform alright. (There's a rather competent-looking phonopre section, too.) So this could be a decent amp if one redid the biasing by modern standards - with the tools and know-how required for such a task. Is it worth the trouble? Well, probably not, unless you really like the looks of this series (they have their fans). There must be any number of far better-performing newer amps out there.
Looking at the schematic for the power amp, I would say that
1. the amp probably is a tad noisy and
2. the biasing arrangement kinda sucks.
Bias is fixed to facilitate manufacturing, and makes use of diodes only (I've never been able to get decent output stage biasing like that). Permitted voltage across the 0.22 ohm emitter resistors is given as 4 to 50 mV, which equates to a bias current of 1 to 12 mA. The output stage is moderately to severely underbiased like that. (Well-performing commercial amps would typically run 30-50 mA to keep temperature in check, the theoretical optimum would be about 100 mA.) Now they can claim a 0.03% THD at 20-20k all day long, but given a 4 ohm load the numbers probably won't look too grand... and the sound may not be either. The drivers are only getting 2 mA, too. Suckers aren't heatsinked either, grrr.
The rest of the power amp circuit looks like it should perform alright. (There's a rather competent-looking phonopre section, too.) So this could be a decent amp if one redid the biasing by modern standards - with the tools and know-how required for such a task. Is it worth the trouble? Well, probably not, unless you really like the looks of this series (they have their fans). There must be any number of far better-performing newer amps out there.
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D'oh! Those used to doing the math have probably noticed that I goofed. 9 to 113 mA would be more like it. Pesky orders of magnitude.
So bias is not necessarily inadequate - but still not particularly well-defined. Carefully measure the voltage across the test points given when you get around to it.
I still don't like that the drivers aren't on the main heatsink. Makes it hard to run them hotter and not mess up thermal stability. Well, there still is a single diode in bias on the PCB, one could bring that in thermal contact with Q16 or Q18.
Hey guys,
Thank you very much for the detailed lowdown on this amp. I think it is perhaps better off belonging to some die hard fan or perhaps someone looking for their first retro amp. I think modding it will only mean more money out of my own pocket.
I managed to fix up the pots and general cracking with some "WD-40 Specialist Contact Cleaner"
WD-40 Specialist Contact Cleaner 400ml | Automotive Lubricants | Screwfix.com
It does sound 'ok' and tbh if I didn't have my Proac + Audiolab combo I might even have liked the sound..
The quest continues.. Maybe pioneer 8500 next
Thank you very much for the detailed lowdown on this amp. I think it is perhaps better off belonging to some die hard fan or perhaps someone looking for their first retro amp. I think modding it will only mean more money out of my own pocket.
I managed to fix up the pots and general cracking with some "WD-40 Specialist Contact Cleaner"
WD-40 Specialist Contact Cleaner 400ml | Automotive Lubricants | Screwfix.com
It does sound 'ok' and tbh if I didn't have my Proac + Audiolab combo I might even have liked the sound..
The quest continues.. Maybe pioneer 8500 next
Ugh. WD-40 has many uses, but I wouldn't let it near my electronics. In particular, it may dissolve plastic and ruin parts (like pots) this way. Cleaning it out with isoprop alcohol is advised.
Contact cleaners need to be chosen carefully, and no small number of devices have been ruined by use of inappropriate ones.
Contact cleaners need to be chosen carefully, and no small number of devices have been ruined by use of inappropriate ones.
I've used WD-40 to clean potentiometers in many junk units when nothing else was around. It works fine and doesn't cause any problems. For sliding pots, though, it doesn't seem to work for very long - otherwise the fix seems to be practically permanent.
I wouldn't use it in any nicer gear though, simply due to the fact that it causes a mess and stinks horribly.
Protip: It works wonders in old noisy computer fans. Just hose down the motor part and it's like new.
I wouldn't use it in any nicer gear though, simply due to the fact that it causes a mess and stinks horribly.
Protip: It works wonders in old noisy computer fans. Just hose down the motor part and it's like new.
I'd just go thru and wholesale replace all the electrolytic caps. use larger values if they fit.
But first clean the connections and contacts etc. Clean the pcb. Then replace all the caps. Re-listen.
If it uses opamps... replacing them would be another thing which could make for a dramatic improvement -- 35 years is a long time ago... opamps are a lot better now.
THx-RNMarsh
But first clean the connections and contacts etc. Clean the pcb. Then replace all the caps. Re-listen.
If it uses opamps... replacing them would be another thing which could make for a dramatic improvement -- 35 years is a long time ago... opamps are a lot better now.
THx-RNMarsh
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Dirt can be cleaned from the pots or switches with anything you like ... you may even use coffee if you like milk and sugar may also help ...Still none of the suggested cleaners is able to clean the oxide that develops on the contacts of the pots and switches that have silver plated pins and parts
At the time these will look very black and this will be a major issue on restoring amplifiers .
Almost none of the sprays existing in the market may be able to solve an issue like that ...Or at least solve it without side effects such is the destroyed plastics and other damages caused by toxic oil or diesel that often is used in some of them
At any case if you use any of the sprays (there is also one that is called De oxit which we have never used before and i don't know if it has any power on the specific oxidation of silver pins and cons . ) you need to rinse or wash the spray left overs with degreaser spray and then apply some other or a very little amount of spray to stay there for lubrication .
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Our company have developed a method for this type of oxidation that works really very well but it required a cost of about 1500 euro to get and a couple of months to make perfect .
We used an ultrasonic dentist tool but modified when it comes to the freq ( pitch was higher ) and the prob ....It actually works perfect as can be seen in the pictures .
After cleaning you just need to blow the amp with air and oxidation drops out as dust ...Modified probs will even work to almost sealed switches though procedure takes much longer ...Add to this that there is no warn to switch or use of any chemical .
The procedure is finished with the application of a very small amount of lubricator that is actually then blown away with pressurized air while still the leftover will be enough to lubricate the switch or pot ...
Enjoy
...Still none of the suggested cleaners is able to clean the oxide that develops on the contacts of the pots and switches that have silver plated pins and parts At the time these will look very black and this will be a major issue on restoring amplifiers .
Almost none of the sprays existing in the market may be able to solve an issue like that ...Or at least solve it without side effects such is the destroyed plastics and other damages caused by toxic oil or diesel that often is used in some of them
At any case if you use any of the sprays (there is also one that is called De oxit which we have never used before and i don't know if it has any power on the specific oxidation of silver pins and cons . ) you need to rinse or wash the spray left overs with degreaser spray and then apply some other or a very little amount of spray to stay there for lubrication .
--------------------------------------------------------------------------------------
Our company have developed a method for this type of oxidation that works really very well but it required a cost of about 1500 euro to get and a couple of months to make perfect .
We used an ultrasonic dentist tool but modified when it comes to the freq ( pitch was higher ) and the prob ....It actually works perfect as can be seen in the pictures .
After cleaning you just need to blow the amp with air and oxidation drops out as dust ...Modified probs will even work to almost sealed switches though procedure takes much longer ...Add to this that there is no warn to switch or use of any chemical .
The procedure is finished with the application of a very small amount of lubricator that is actually then blown away with pressurized air while still the leftover will be enough to lubricate the switch or pot ...
Enjoy
I love the ultrasonic implementation, it is a great idea and I wish you the best of luck
The problem you may face when introducing such service into hifi circles is the cost! for 1500 I may as well get a new amp. Is there a way to make the solution more affordable and mass market it?
Are you a fan of Dragons Den? Its a weird, tongue-and-cheek yet funny and interesting UK TV programme. So, in words of Peter Jones, "...and for that reason, I am out"
A repair guy in a forum I frequent uses an ultrasonic bath (ordinary consumer level one, I think) and water with some classic household metal cleaner. Seems to work for him, and it's useful for parts that you don't want to take apart for fear of a thousand tiny pieces flying around (not unwarranted in some cases).
The cheapskate version of sealing cleaned metal surfaces is vaseline (spray versions also exist).
The spray cleaners which are most commonly used here appear to be totally unknown elsewhere. I have yet to map out what corresponds to which version of DeoxIT.
The cheapskate version of sealing cleaned metal surfaces is vaseline (spray versions also exist).
The spray cleaners which are most commonly used here appear to be totally unknown elsewhere. I have yet to map out what corresponds to which version of DeoxIT.
Silver plating soon blackens in urban environments, particularly with fossil fuel power generation, steel plants and refineries. I have had amplifiers that were completely silent because silver plated contacts were partly blackened but you can limit the amount of blackening chemically, in a process known generally as metal passivation. I do it for next to no cost because as a chemist, I get what I need from unlikely sources and substitute anything that has a chance of working.
If you have to buy a special product as a retail preparation with incredible mark-ups, documentation and safety advice and videos explaining and promoting it like this one this video - well, you have to pay for all that security. 'Nice product though.
If you have to buy a special product as a retail preparation with incredible mark-ups, documentation and safety advice and videos explaining and promoting it like this one this video - well, you have to pay for all that security.
'Nice product though.
Standard WD40 is a, just like the name says, WATER DISPLACEMENT spray. It is not a lubricant. It will gum up as it ages. Don;t use it on your carb, it will stick and a stuch throttle is no fun. I wil check out their new special cleaner. New to me.
Yea, those vintage Pioneers were all pushy in the midrange. Hard to remember that far, but my first "real" amp was a 7100 I think. Anything over 7 to 10 years old needs a recap, which can cost as much as a new amp.
I love the old aesthetics. I would gut it and put a gain clone in it. Save the transformer , heat sinks etc. Whip up a simple op-amp preamp ( $12 ones off e-bay are fine) . Maybe a MX-50 kit.
Yea, those vintage Pioneers were all pushy in the midrange. Hard to remember that far, but my first "real" amp was a 7100 I think. Anything over 7 to 10 years old needs a recap, which can cost as much as a new amp.
I love the old aesthetics. I would gut it and put a gain clone in it. Save the transformer , heat sinks etc. Whip up a simple op-amp preamp ( $12 ones off e-bay are fine) . Maybe a MX-50 kit.
I just got one SA-610, and not knowing anything about it, I went surfing for info. Luckily, I got it for free, because it would be a real pain reading how bad it is, if I paid money for it.
Putting a gainclone in it seems like a great idea! Maybe even some cheap but okay class D amps? Has anyone done it already? I woud keep the input selection, volume and VU-meter, if this is even possible.
I never modded any audio gear, apart from changing the caps on a TPA3116
How hard would it be to do it?
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