Jbl sa600

Hi

I need your advice, friends.

Please take a look at the vintage JBL SA600 integrated power amplifier.
Do any of you know what are those two RCA-like connectors on the panel right behind the capacitors? Two separate wires from them are seen soldered on the power amp circuit board and preamp board on the back. Some say they simply bridge pre and power section, so they don't affect sound. Actually I found one on ebay, without those connectors. Is it safe for me to buy such an item without those connectors? Thanks as always for your help.

I've added two more pics for your judgement. Thanks.

you have the manual... yes?

Attachment 63891

Quote:

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Originally Posted by grumpy

you have the manual... yes?

Attachment 63891

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Thanks a lot, grumpy. I don't have the manual.
So, let me double check if I get it right:
The two connectors (signal connections?) here have nothing to do with sound reproduction and
the whole purpose is to check the performance of the power amp, as the manual says?

By the way, the attached pic shows some modification, where you see the two RCA jacks on the panel...

I believe this is an internal connection, that would normally (these days)
be brought out as pre-out, amp-in, but which has been left internal on this model,
such that they could be disconnected and one could then test the two
sections independently without unsoldering anything.

If the internal RCA plug interface is missing, then someone could very well
have hardwired this connection (which should be audibly fine, but not
accurate for the period in terms of being original).

That last pic looks like someone replaced the original wiring/plugs
with whatever they had available (again, functional, but not accurate).

If you unplugged these, I would expect that would be like removing the
cables between a preamp and amplifier.

If you google "SA600 and JBL" you should find a JBL-sourced pdf file of the manual.

Quote:

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Originally Posted by pyonc

The two connectors (signal connections?) here have nothing to do with sound reproduction

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:no: regarding the manual extract and as grumpy said the 2 connectors with cables are the L and R connexions the signal go through from preamp to power amp

Quote:

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Originally Posted by pyonc

the whole purpose is to check the performance of the power amp, as the manual says?

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:yes: for that you have to remove the 2 connectors and connect an external source replacing the preamp during audio test

Quote:

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Originally Posted by ratitifb

:no: regarding the manual extract and as grumpy said the 2 connectors with cables are the L and R connexions the signal go through from preamp to power amp

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Hummmm..... That's a very good point. Thanks for your feedback!

Quote:

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Originally Posted by grumpy

If the internal RCA plug interface is missing, then someone could very well
have hardwired this connection (which should be audibly fine, but not
accurate for the period in terms of being original).

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Yes, that's what I guess. As a JBL purist, I don't like that kind of modification, even though it has little effect on sound.
Your explanation helped a lot. Thanks much!:D

Quote:

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Originally Posted by pyonc

Yes, that's what I guess. As a JBL purist, I don't like that kind of modification, even though it has little effect on sound.
Your explanation helped a lot. Thanks much!:D

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Every connector is a point of failure. Eventually it will tarnish and affect the quality of the connection.
Forgotten internal connections like this are a potential problem.
Much better to have jumper wires that are directly soldered for point to point connection.

Just my personal opinion, of course. ;)

I'm with Heather on this one, also every connector is always an unneccessary resisistance in the signal path.

If you don't mind the originality and plan to keep your amp you kan bypass the connectors with some good quality wire.

KISS Keep it solid.

Quote:

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Originally Posted by pyonc

Hi

I need your advice, friends.

Please take a look at the vintage JBL SA600 integrated power amplifier.
Do any of you know what are those two RCA-like connectors on the panel right behind the capacitors? Two separate wires from them are seen soldered on the power amp circuit board and preamp board on the back. Some say they simply bridge pre and power section, so they don't affect sound. Actually I found one on ebay, without those connectors. Is it safe for me to buy such an item without those connectors? Thanks as always for your help.

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May i ask you where you bought the JBL SA600 amp ? It looks the same as the JBL SA600 amplifier i restored a few years ago.

Have a look at:

http://audioheritage.org/vbulletin/s...ad.php?t=15522

http://audioheritage.org/vbulletin/s...ad.php?t=18937

Kind regards,

Jan Slagman
Veenendaal
The Netherlands

Quote:

---

Originally Posted by pyonc

Hi

I need your advice, friends.

Please take a look at the vintage JBL SA600 integrated power amplifier.
Do any of you know what are those two RCA-like connectors on the panel right behind the capacitors? Two separate wires from them are seen soldered on the power amp circuit board and preamp board on the back. Some say they simply bridge pre and power section, so they don't affect sound. Actually I found one on ebay, without those connectors. Is it safe for me to buy such an item without those connectors? Thanks as always for your help.

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I think that amp has been mine ! Does it have an Alps volumecontrol ? The electronics of the JBL SA600 was restored by Mr.Ruud Janssen an "old skool" audiocraftsman and audioreviewer.

Kind regards,

Jan Slagman
Veenendaal
The Netherlands.

Hello. Does anyone have a recommendation of a tech to work on JBL SA600? I would prefer someone who has worked on SA600 before. Also any source for transistors for the SA600?