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Vintage Receivers

mhardy6647

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My old SX727 Pioneer has an excellent FM tuner...excellent. But the low watts per channel
really limit it. Cool looking and very 70's! It is on a shelf, unused. It needs caps...again.

It is the only tuner I own. I only use CD's now.
I think I've got one of those, too.
DSC_0322 by Mark Hardy, on Flickr

Other than being attractive and fairly beefy, it really didn't make much of an impression on me. It hasn't been hooked up/used for quite a while.
 

cistercian

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Yep. Not impressive except for FM reception for me. Pretty though and I scored it for free.
 

bigx5murf

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I just picked up this one today for $20.
20200829_020337.jpg


Someone mentioned a concept, I have a cosmetically mint 7.5D with a bad preamp section, and I don't have the ability to repair it :(
 

Doodski

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mhardy6647

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I just picked up this one today for $20.View attachment 80445

Someone mentioned a concept, I have a cosmetically mint 7.5D with a bad preamp section, and I don't have the ability to repair it :(
sha-weet. Does it work? ;)

Kinda, sorta on topic: looky what I was listenin' to last night...

DSC_0365 (2) by Mark Hardy, on Flickr

PS If it makes you feel any better @bigx5murf, I hate workin' on soiled state electronics: so picky (gotta worry about tenths or even hundredths of volts, or stuff blows up), so fragile (ditto... and static-sensitive)... and so complicated :( Why use one tube when you can use 200 transistors and a regulated power supply? Sorry -- I am actually OK with soiled state stuff, there's a place for it... but not as something for me to troubleshoot and repair. :(
I think that's why the high-tech state of the art has evolved to disposable electronics -- the "technology" changes so fast, the little boxes that access it are ephemeral. Of course, that does leave humankind with that itty-bitty e-waste problem. :oops:
 

bigx5murf

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sha-weet. Does it work? ;)

Kinda, sorta on topic: looky what I was listenin' to last night...

DSC_0365 (2) by Mark Hardy, on Flickr

PS If it makes you feel any better @bigx5murf, I hate workin' on soiled state electronics: so picky (gotta worry about tenths or even hundredths of volts, or stuff blows up), so fragile (ditto... and static-sensitive)... and so complicated :( Why use one tube when you can use 200 transistors and a regulated power supply? Sorry -- I am actually OK with soiled state stuff, there's a place for it... but not as something for me to troubleshoot and repair. :(
I think that's why the high-tech state of the art has evolved to disposable electronics -- the "technology" changes so fast, the little boxes that access it are ephemeral. Of course, that does leave humankind with that itty-bitty e-waste problem. :oops:

The Yamaha R9 seems to be fully functioning, just missing it's door. I'm not sure why there's two volume controls.

My concept 7.5d still technically functions fully. But it causes woofer pumping. Issue is gone if I use another preamp fed into the power amp section.
 

restorer-john

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My old SX727 Pioneer has an excellent FM tuner...excellent. But the low watts per channel
really limit it. Cool looking and very 70's! It is on a shelf, unused. It needs caps...again.

Its bigger brother the SX-737, just got a set of 4mm binding posts fitted (and a complete rebuild) for a good friend.

DSC_2322.JPG


DSC_2321.JPG
 

mhardy6647

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The Yamaha R9 seems to be fully functioning, just missing it's door. I'm not sure why there's two volume controls.

My concept 7.5d still technically functions fully. But it causes woofer pumping. Issue is gone if I use another preamp fed into the power amp section.

Your R-9 has a (flat) volume control and, concentrically mounted, Yamaha's long-time signature variable loudness control. The latter approximates the Fletcher-Munson (etc.) curves, but allows flexibility and adjustability that most "loudness" controls of the era didn't. The idea was (is) this: with the loudness set "flat", turn up the volume to the loudest level you're likely to routinely listen to. Thereafter, use the loudness control to reduce the sound output level (rather than the volume control), thus -- theoretically ;) -- giving you reasonably 'accurately perceived' frequency response irrespective of SPL.
1599011129496.png

If nothing else, it's more flexible than most loudness control schemes.
The concentric volume/loudness is nice. Typically, Yamahas had a big volume control and a smaller, separate loudness control. :rolleyes:
See, e.g., my much beloved CA-610II integrated amp, which I have owned since it was new (1978).

P1020541 by Mark Hardy, on Flickr

As an aside: Variable loudness was not uncommon in the early days of consumer hifi ('50s into the early '60s).

EDIT: If you don't have a manual for your R-9, you can get one at https://www.hifiengine.com/manual_library/yamaha/r-9.shtml
Free registration required to access their content, and well worth it IMO. If you have any trouble registering, send me a PM and I can offer some form of assistance :)

Also -- your poor Concept. Sounds like LF oscillation motorboating) or maybe DC getting through to the speakers :( Not a good thing -- but nice to know you were able to isolate it to the preamp section.
 
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restorer-john

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thus -- theoretically ;) -- giving you reasonably 'accurately perceived' frequency response irrespective of SPL.

Some Yamaha implementations were good, others, not so much. Even the current model AS-xxx series use the variable loudness and it doesn't do too bad of a job. Most don't come close to the fletcher munson curves, despite what Yamaha told us...

Yamaha AS-300 loudness contours at equal dB (marked) steps from flat.
yamaha as300 loudness.png
 

mhardy6647

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Some Yamaha implementations were good, others, not so much. Even the current model AS-xxx series use the variable loudness and it doesn't do too bad of a job. Most don't come close to the fletcher munson curves, despite what Yamaha told us...

Yamaha AS-300 loudness contours at equal dB (marked) steps from flat.
View attachment 80971

Indeed.
Truth be told -- I was too lazy to go too deep into the whole "Fletcher-Munson" thing in the context of the Yamaha R-9's volume control. ;)
Further truth be told -- I have used the variable loudness on any Yamaha gizmo only very rarely... but -- as loudness contours go -- I still like the idea of a variable one. :)

EDIT: Here's (FWIW) the advertised behavio(u)r of the variable loudness on the CR-2020 receiver...

YamahaCR-2020loudnesscurves by Mark Hardy, on Flickr

Semi-monstrous 1970s soiled state receivers by Mark Hardy, on Flickr
CR-2020 on the right
 
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mhardy6647

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Cannot think of Stasis without thinking of Red Dwarf.
(Nelson Pass notwithstanding)

:)
 

bigx5murf

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Still running a Nakamichi TA-3A Stasis receiver in the master bedroom. :)

I've owned one of these before. I recall it having a lot of bottom end despite the low power rating.
 

Doodski

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Still running a Nakamichi TA-3A Stasis receiver in the master bedroom. :)
A nice receiver but the TA-4 has the extra features like 2 pre-outs at the rear,
1 more AC plug in and stuff according to these docs. :D
Had a couple rye's and a bowl full and checked out the receiver.
Front _6.jpg

Nakamichi TA-3 _1.png
Nakamichi TA-3 _2.png
Nakamichi TA-3 _3.png

Nakamichi TA-3 _4.png


Apparently the STASIS circuitry, "...eliminates the need for negative feedback in the amp output section."

Output Stage Pic #1 w/power supply.
Nakamichi TA-3 _5.png

Output Stage Pic #2 w/complete output stage.
Nakamichi TA-3 _6.png
 

smallricey

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