Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 7th March 2014, 12:28 AM   #1
diyAudio Member
 
Join Date: Oct 2013
Exclamation Pioneer SA-610 mods to improve sound quality

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?
  Reply With Quote
Old 7th March 2014, 07:16 PM   #2
diyAudio Member
 
Join Date: Mar 2013
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.
__________________

Last edited by Welcome; 7th March 2014 at 07:18 PM.
  Reply With Quote
Old 7th March 2014, 08:42 PM   #3
sreten is online now sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
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.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 7th March 2014 at 09:05 PM.
  Reply With Quote
Old 7th March 2014, 09:51 PM   #4
diyAudio Member
 
Join Date: Nov 2004
Location: Germany
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.

Last edited by sgrossklass; 7th March 2014 at 09:55 PM.
  Reply With Quote
Old 7th March 2014, 11:04 PM   #5
diyAudio Member
 
Join Date: Nov 2004
Location: Germany
Quote:
Originally Posted by sgrossklass View Post
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.
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.
  Reply With Quote
Old 8th March 2014, 12:18 AM   #6
diyAudio Member
 
Join Date: Oct 2013
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
  Reply With Quote
Old 8th March 2014, 02:40 PM   #7
diyAudio Member
 
Join Date: Nov 2004
Location: Germany
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.
  Reply With Quote
Old 8th March 2014, 06:21 PM   #8
diyAudio Member
 
Join Date: Oct 2013
I know what you mean about standard WD40, but this is the new, special stuff especially designed for electronic contacts etc
  Reply With Quote
Old 8th March 2014, 10:33 PM   #9
diyAudio Member
 
Join Date: Apr 2010
Quote:
Originally Posted by sgrossklass View Post
Ugh. WD-40 ....it may dissolve plastic and ruin parts (like pots) this way.
WD40 will not dissolve ANY plastics.
  Reply With Quote
Old 9th March 2014, 09:24 AM   #10
diyAudio Member
 
Join Date: Mar 2013
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.
__________________
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pioneer SA-610 - bypass the Pre-amp stage? dakku Solid State 11 5th March 2014 08:43 PM
Mods to Improve Andrew Jones Pioneer Speakers? Ben_Tech Multi-Way 12 5th March 2014 01:55 AM
WTB - Pioneer SA-610 front panel Studio1 Swap Meet 0 11th January 2012 12:55 AM
Pioneer sa-610 wiseboy1900 Solid State 1 14th September 2011 04:40 PM
Do these HTPC mods & tweaks improve sound? cdwitmer Digital Source 11 23rd May 2003 09:06 PM


New To Site? Need Help?

All times are GMT. The time now is 08:19 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2