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What would cause a Pioneer SA-6700 to have a wooly sound?

166.216.165.27

Posted on December 9, 2016 at 13:23:27

LowRedMoon
Audiophile

Posts: 1091
Location: Central PA
Joined: February 28, 2006

I build new tube amps as a hobby, but I'm not too familiar with working on old solid state equipment.
This is the SA-6700 with two power meters on the front. It's in very good shape. In general, the sound is very pleasing, with good texture and detail, but there's kind of a warm, wooly quality laying over the sound - especially with the phono section, regardless of cartridge or speakers.
Replacing the electrolytics would be simple enough, but I don't want to waste the caps. if it's not going to yield improvement.
Is this quality common with older gear? If so, what are the causes?

Thank you,

Adam

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Service Manual.

Timbo in Oz

12:31:07 12/12/16

Replace all teh PSU caps, replace the PSU diodes with Schottkys, and then listen.

Timbo in Oz

13:28:22 12/10/16

RE: Replace all teh PSU caps, replace the PSU diodes with Schottkys, and then listen.

sony6060

06:35:21 12/12/16

...

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Service Manual.

Timbo in Oz

12:31:07 12/12/16

Replace all teh PSU caps, replace the PSU diodes with Schottkys, and then listen.

Timbo in Oz

13:28:22 12/10/16

RE: Replace all teh PSU caps, replace the PSU diodes with Schottkys, and then listen.

sony6060

06:35:21 12/12/16

It's an SS integrated amplifier.

Timbo in Oz

12:29:03 12/12/16

RE: What would cause a Pioneer SA-6700 to have a wooly sound?

gordguide

08:19:11 12/10/16

I had the Pioneer SA-9700 and they are worth the effort

airtime

15:44:45 12/09/16

RE: I had the Pioneer SA-9700 and they are worth the effort

LowRedMoon

18:40:03 12/09/16

Maybe being a "mammoth" amount of years old?? :)

popsy

14:34:26 12/09/16

RE: Maybe being a "mammoth" amount of years old?? :)

LowRedMoon

14:39:28 12/09/16

Maybe being a "mammoth" amount of years old?? :), posted on December 9, 2016 at 14:34:26
popsy Audiophile Posts: 2713 Location: oregon Joined: March 4, 2007	:)

RE: Maybe being a "mammoth" amount of years old?? :), posted on December 9, 2016 at 14:39:28
LowRedMoon Audiophile Posts: 1091 Location: Central PA Joined: February 28, 2006	Makes sense!

I had the Pioneer SA-9700 and they are worth the effort, posted on December 9, 2016 at 15:44:45
airtime Audiophile Posts: 11287 Location: Arizona Joined: February 4, 2003	I had the Pioneer SA9700 and the last thing I would describe the sound as is wooly. the caps are pretty much on their last legs. Recap one section at a time and see what improvements you hear. the SAs were an excellent quality line. I say go for it. And post every thing you find after you start. good luck charles

RE: I had the Pioneer SA-9700 and they are worth the effort, posted on December 9, 2016 at 18:40:03
LowRedMoon Audiophile Posts: 1091 Location: Central PA Joined: February 28, 2006	Thanks for your input. The sound is certainly good -- silky smooth and pleasant. I can hear that there's a good presentation hidden under the fog. I'll start taking it apart this weekend. Adam

RE: What would cause a Pioneer SA-6700 to have a wooly sound?, posted on December 10, 2016 at 08:19:11

gordguide
Audiophile

Posts: 302
Joined: January 20, 2002

In my experience, that is the typical sonic signature of a 70's era Japanese receiver. The main culprit is the phono preamp; try almost any reasonably good 3rd party phono pre into an unused line level input and see what you think. Ideally just borrow one (a decent one; avoid the $50 specials) and see if that brings some naturalness to male vocals and bass instruments.

I'm sure you will then decide to seek out a Phono Preamp that meets your quality requirements.

Your phono cartridge choice could be contributing. Some are a little dark to begin with, and the combination doesn't add up well.

There are many Phono Preamps that are decent at about $100, and you can certainly hear improvements in Sound Quality (SQ) as you go up in price. If you don't need Moving Coil capabilities, you can keep it under $500 and do quite nicely. My advice would be if you do decide to try a MC pickup to go the transformer route in combination with your chosen MM pre-preamplifer, but that's another topic.

Replace all teh PSU caps, replace the PSU diodes with Schottkys, and then listen., posted on December 10, 2016 at 13:28:22
Timbo in Oz Audiophile Posts: 23221 Location: Canberra - in the ACT - SE Australia Joined: January 30, 2002	Then replace all the signal coupling caps, where they will fit use PProp film caps esp. in the phono stage. It's likely that you can increase the capacitance of the PSU with same size caps with higher uf. This is always a good thing. Warmest Tim Bailey Skeptical Measurer & Audio Scrounger

RE: Replace all teh PSU caps, replace the PSU diodes with Schottkys, and then listen., posted on December 12, 2016 at 06:35:21
sony6060 Audiophile Posts: 1465 Location: USA Joined: August 8, 2014	Frankly, I never heard a SS receiver outperform a good tube receiver. Best I ever heard in SS are the all discrete design (no op amp) Sony STR-6060FW.

It's an SS integrated amplifier., posted on December 12, 2016 at 12:29:03
Timbo in Oz Audiophile Posts: 23221 Location: Canberra - in the ACT - SE Australia Joined: January 30, 2002	Yes? If the FM band isn't crowded, a restored/rebuilt valve receiver, or valve tuner, driven hard by a directional antenna will eat most SS FM stages and the output stage, in any SS receiver or a tuner. IME that is. Whether there's a valve rectifier in it OR SS diodes. Warmest Tim Bailey Skeptical Measurer & Audio Scrounger

Service Manual., posted on December 12, 2016 at 12:31:07

Timbo in Oz
Audiophile

Posts: 23221
Location: Canberra - in the ACT - SE Australia
Joined: January 30, 2002

Click below.

Warmest

Tim Bailey

Skeptical Measurer & Audio Scrounger

http://www.hifiengine.com/manual_library/pioneer/sa-6700.sht

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