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Author Topic: Germanium phono preamp based on the JBL SG520  (Read 54 times)
mamakasou
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« on: Today at 12:39:37 PM »

Hi!

Found a populated PCB on ebay, claiming to be a clone of the JBL SG520 design using Soviert-era Germanium transistors.

The interesting part is in the description of the item where it says that it's 'made according to the version of the “vs music” scheme'.
He even gives special thanks to "vs music" for the work done.

I don't know if Victor is aware of it.
Maybe, he is.

Anyway, I couldn't resist and now it is on its way.

I've been interested in trying out a germanium-based design for some time now and was pleasantly surprised to find such an offer.
Ideally, I would have made it myself, but to be honest I prefer to pay save some time and effort.

For anyone interested, will be back with impressions and some pictures when it arrives.

By the way, does anybody know something more about the SG520?
Looks like it was marketed more for the professional market.

PS: don't know whether it is allowed to add a link to the actual listing but if you search ebay for it, you will find it.
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vs music
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« Reply #1 on: Today at 02:07:28 PM »

Hello!
Yes, I know about this Russian SG-520 assembly.
This guy (his name is Eugene) There are also assemblies of several other phonopreamps on germanium transistors. He sells them inexpensively . He designed the printed circuit boards himself .
 I have nothing to do with this small business.
We discussed different circuits on germanium transistors. And he decided to make several versions of phonopreamps using military transistors of the USSR .
I hope you won't be disappointed with your purchase.
« Last Edit: Today at 02:13:06 PM by vs music » Logged

Victor
vs music
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« Reply #2 on: Today at 02:22:45 PM »

The SG-520 was a fairly expensive preamp (over $400 in the 60s). Its design was unique for those years.





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Victor
mamakasou
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« Reply #3 on: Today at 02:22:59 PM »

Yeah, he offers several phono preamp designs as you mentioned.
Decided to go for the JBL-based remembering our conversation regarding which sounds best.

I was also interested on the Fischer-based design, mostly because of its historic value.
You have tried it too. What do you think of its sound?

If I like what I hear with the JBL-based one I will try some more for sure.
 
PS: Also ordered the headphone amplifier, based on a design by Beslik.
Have an abundance of tube-based, solid-state and opamp headphone amplifiers but couldn't resist to add a germanium one to the collection.

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vs music
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« Reply #4 on: Today at 03:03:11 PM »

Yeah, he offers several phono preamp designs as you mentioned.
Decided to go for the JBL-based remembering our conversation regarding which sounds best.

I was also interested on the Fischer-based design, mostly because of its historic value.
You have tried it too. What do you think of its sound?

If I like what I hear with the JBL-based one I will try some more for sure.
 
PS: Also ordered the headphone amplifier, based on a design by Beslik.
Have an abundance of tube-based, solid-state and opamp headphone amplifiers but couldn't resist to add a germanium one to the collection.


I liked the sound of my Fisher TR-1 preamp clone.
 It also showed a fairly good transient response on a 1khz/10khz/20khz meander (via a reverse RIAA circuit) .
 Here are some graphs ( measured at the output of this phono preamp )...







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Victor
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