Today, I rule!
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Cargo Master
Joined: Jan 2004
Posts: 2,512
Likes: 8
From: Cook Forest and Irwin PA
Today, I rule!
Started working on a 1982 Pioneer SX3800 I accidently won on ebay...
It seemed the tuner was a bit intermittent. I was actually getting stereo sep at about 15% ref signal strength, but sometimes, no bars on the meter, sometimes a few. So off comes the bottom.
Poking around I find a signal wire from the IF section loose on the board. jumped the trace points - 80% signal using a stupid dipole hung on the kitchen light/fan (oh yeah, I use a $1500 oak table for a stereo workshop!)
gotta clean up the tape mon switches, vol control, balance both need some deoxit. Of course Im gonna balance the amp - who wants to place bets on the DC offset? Im betting <20mv
It seemed the tuner was a bit intermittent. I was actually getting stereo sep at about 15% ref signal strength, but sometimes, no bars on the meter, sometimes a few. So off comes the bottom.
Poking around I find a signal wire from the IF section loose on the board. jumped the trace points - 80% signal using a stupid dipole hung on the kitchen light/fan (oh yeah, I use a $1500 oak table for a stereo workshop!)
gotta clean up the tape mon switches, vol control, balance both need some deoxit. Of course Im gonna balance the amp - who wants to place bets on the DC offset? Im betting <20mv
Post Fiend
Joined: Mar 2004
Posts: 24,418
Likes: 3
From: San Francisco, Ca.
Nice find. Very nice. 
I was going to off my old early eighties Yamaha integrated amp and matching
tuner, but opted to keep them instead. Glad I did.
For some reason, it sounds better than my '95 Yamaha receiver, so guess which
one I'm currently using?
I was going to off my old early eighties Yamaha integrated amp and matching
tuner, but opted to keep them instead. Glad I did.
For some reason, it sounds better than my '95 Yamaha receiver, so guess which
one I'm currently using?
Thread Starter
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Cargo Master
Joined: Jan 2004
Posts: 2,512
Likes: 8
From: Cook Forest and Irwin PA
I am so in biz....who wants to buy a rock stable perfectly clean amp?
Left DCO: 18mv, right: 43mv, after mr magic screw driver: .9mv each
set the idle current by adjusting the bias voltage on each channel.
turning all the pots to 0 like the SM says left channel: 2v+!!!! (120mv is the first spec)
could not get her lower than 165mv, right channel was bouncing 400mv, then I got it to a 150mv average (2nd adjustment) but it was bouncing and the heat sink was like an exhaust manifold - painful
shut her off, penned a note to an acquaintance at audiokarma.org, came back, flicked it on - stable.
so taking a chance I used the full procedure and set the bias to 120 then 150mv - rock stable, been running now 30 minutes. Im thinking when I had the amp unbalanced the idle bias took off and at zero volume essentially drove her full blast - I recall reading there is some thermal tracking in here...
About to do a full power test into 8 ohm 200w dummies.
What is an SX3800 you ask? a 60wpc amp that has, get this: .005% distortion. and has a phono section s/n ratio about that of CD's (the sx3900 is its muscular older brother - 120w)
Left DCO: 18mv, right: 43mv, after mr magic screw driver: .9mv each
set the idle current by adjusting the bias voltage on each channel.
turning all the pots to 0 like the SM says left channel: 2v+!!!! (120mv is the first spec)
could not get her lower than 165mv, right channel was bouncing 400mv, then I got it to a 150mv average (2nd adjustment) but it was bouncing and the heat sink was like an exhaust manifold - painful
shut her off, penned a note to an acquaintance at audiokarma.org, came back, flicked it on - stable.
so taking a chance I used the full procedure and set the bias to 120 then 150mv - rock stable, been running now 30 minutes. Im thinking when I had the amp unbalanced the idle bias took off and at zero volume essentially drove her full blast - I recall reading there is some thermal tracking in here...
About to do a full power test into 8 ohm 200w dummies.
What is an SX3800 you ask? a 60wpc amp that has, get this: .005% distortion. and has a phono section s/n ratio about that of CD's (the sx3900 is its muscular older brother - 120w)
Post Fiend
Joined: Mar 2004
Posts: 24,418
Likes: 3
From: San Francisco, Ca.
and ran his test equipment to test the distortion level.
The Yamy specs out at .005% distortion @ 105 watts/rms.
When he tested it, he shook his head. He got readings of .0015% @ 120 watts.
This unit just seems to sound more dynamic than my other Yamy.
Keep your new find. It's a classic.
Thread Starter
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Cargo Master
Joined: Jan 2004
Posts: 2,512
Likes: 8
From: Cook Forest and Irwin PA
Ilove the sound of the old pioneer silvers...my smallest one (1977 SX450) is only 15 watts, and it has a set of matched pioneer speakers - it will fill your yard with sound and the '50' series I have had are not that great in the distortion department. All the '80' series units put it into the .02-.05 range which is at least 10x better than the crap available today. the 'muscle' 3xxx units are a world unto their own like the D7-d9 servo units or the famous sx-1980 (Id love to have those, I just dont have the $1200 to get a decent fixer-upper)
btw - you might find that your yammie runs stable into 6 or even 4ohm loads and gets near 140-150 watts. The trick is - pc cooling fans on top lifting heat, powered by a small dc transformer. keep em cool. a lot of the amp trannys are unobtanium nowadays
btw - you might find that your yammie runs stable into 6 or even 4ohm loads and gets near 140-150 watts. The trick is - pc cooling fans on top lifting heat, powered by a small dc transformer. keep em cool. a lot of the amp trannys are unobtanium nowadays
Post Fiend
Joined: Mar 2004
Posts: 24,418
Likes: 3
From: San Francisco, Ca.
Ilove the sound of the old pioneer silvers...my smallest one (1977 SX450) is only 15 watts, and it has a set of matched pioneer speakers - it will fill your yard with sound and the '50' series I have had are not that great in the distortion department. All the '80' series units put it into the .02-.05 range which is at least 10x better than the crap available today. the 'muscle' 3xxx units are a world unto their own like the D7-d9 servo units or the famous sx-1980 (Id love to have those, I just dont have the $1200 to get a decent fixer-upper)
btw - you might find that your yammie runs stable into 6 or even 4ohm loads and gets near 140-150 watts. The trick is - pc cooling fans on top lifting heat, powered by a small dc transformer. keep em cool. a lot of the amp trannys are unobtanium nowadays
btw - you might find that your yammie runs stable into 6 or even 4ohm loads and gets near 140-150 watts. The trick is - pc cooling fans on top lifting heat, powered by a small dc transformer. keep em cool. a lot of the amp trannys are unobtanium nowadays
105 per channel is just fine with me.
BTW, I did run an even older Yamy through my first model ESS AMT-1 speakers
that I'm kicking myself in the a$$ first offing those a long time ago.
I do, however, have a pair of old Infinity RSM speakers that just kick butt.
A basic infinite baffle with a 12'' woof, 5'' mid, and the famous EMIT tweeter.
I just have to re-surround the woofs.
Fun Fun Fun
Postmaster
Joined: Dec 2007
Posts: 4,151
Likes: 0
From: Moonlight Moose Enclosure
Trending Topics
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Cargo Master
Joined: Jan 2004
Posts: 2,512
Likes: 8
From: Cook Forest and Irwin PA
Well since someone said you look like Carly Simon, bring over some Carly simon records (yes records, unless you got SA CDs - leave the regular crap CDs at home) and we will let you hear what a real stereo amp should sound like. Even compare it to the 'top of the line' you can get today, to the middle of the road for 4 manus from the 70's.
Hear the difference bewteen a 'warm pioneer' and a 'non switching pioneer' and a Sansui and a Kenwood, at normal volumes, thru good speakers
Hear the difference bewteen a 'warm pioneer' and a 'non switching pioneer' and a Sansui and a Kenwood, at normal volumes, thru good speakers
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Fleet Mechanic
Joined: Feb 2005
Posts: 1,782
Likes: 15
From: Lower Mainland B.C.
okay, whats the dif between SA cds and crap cds? what does SA stand for? I have a few cds from the mid 80s, are they better quality? what should I look for? I buy all my cds from thrift stores...
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Cargo Master
Joined: Jan 2004
Posts: 2,512
Likes: 8
From: Cook Forest and Irwin PA
Most DVD players btw can do SA CDs (dont do MP3 or WMA CDs and expect good sound - those formats are for Ipods and earbuds only!) and you can get SA CDs at better music stores, sometimes bestbuy, and thru amazon - expect to pay 20-25 each
Thread Starter
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Cargo Master
Joined: Jan 2004
Posts: 2,512
Likes: 8
From: Cook Forest and Irwin PA
As of 2 hours ago, this 3800 is now my daily driver in this room, replacing my trusty steed - a 780. what a difference in sound. and the 780 does not suck. running into a set of 1977 lafayette criterion L6's
anyone wanna buy a warranted 780 for $75?
anyone wanna buy a warranted 780 for $75?
Senior User
Joined: Jan 2006
Posts: 140
Likes: 0
From: Dent,Mn
you guys kill me...my sterio is 25 yrs old,my direct drive turn table needs a new needle, my 45s are old but good, good collection of 33 and 78's,have a box full of 8 tracks and some casettes tapes,think I own maybe 10 cd's......my pioneer system still rocks....
Postmaster
Joined: Dec 2007
Posts: 4,151
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From: Moonlight Moose Enclosure
OMG I still do not get it. I need to see if the local college offers Pioneer 101
But I have to admit if all this "jargon" were whispered in my ear it you guys could make it sound beyond erotic. lol
But I have to admit if all this "jargon" were whispered in my ear it you guys could make it sound beyond erotic. lol