Sonab amplifier information?

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#2
Hi again,

I found some schematics for the amp, however not being a pro means i cant really get a gut feelin for the design...

The link for the schematics is
url]http://www.arky.ru/audio/shem/sb4000.zip[/url]

What do people think about this amp ??


Thanks,
 
#4
Hi peranders,

Thanks for your reply.

Im thinking this amp should deliver around 50wpc ? What do you think about replacing the 2N3055 in the output stage with something like MJ15003/15004. Would that provide much improvement in sound ? Do you think it would require adjustments if this was done ?

I've looked and looked, but there seems to be very little information around...

Thanks again
 
#5
I think Sonab was just a local swedish brand back in the 70's.
I didn't even remember them making amps. They were mainly
known for their speakers, but there were a lot of swedish
brands of speakers, very few of which were known outside
Sweden I guess. Maybe some of the other swedes on the
forum knows something more about the amp, but I doubt
it had much of a reputation even here.
 
#7
from 1977
 

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#8
I happen to have a Sonab 4000R-2/S, the one to the right in the picture Bandit added.

I found a schematic inside my receiver, it was taped under the cover.

The ouput transistors are some strange Motorola 7320001 in TO3 "cans" and marked as well in my schematic 7320001...
 
#9
Hi,

thanks for the info!

I think that the p4000 and the r4000 are somewhat different. My p4000 definately uses a 2n3055 and a Motorolla for the pnp. The apperance is also a little different as it doesnt have the dials next to the selector switch (it has mic in, and headphone out). However apart from that the amps look identical.

I got the amp with the left channel blown. So im trying to decide whether i should try to fix the amp, try to refund it or whether to try to put something else into the case. While im at it, would anyone know what the problem in the left channel could be?

Cheers,
Vas.
 
#10
vazzy said:
The apperance is also a little different as it doesnt have the dials next to the selector switch (it has mic in, and headphone out). However apart from that the amps look identical. Vas.
Click to expand...

The dial is for the FM tuner. Because Australia didn't have FM back then, the Australian version of the amp omitted it and replaced it with the mic and headphone sockets.

Glenn
 
#11
I concur that the design is great looking. All black with orange/red lights.

I picked up a 3000 sonab for $12 at snowline (sort of like a salvation army). Unfortunately it didn't play and after mucking around with it for a while, decided to strip it for parts. Good knobs, lights, case. The transformer looks impressive. Engel I think. with 55V and 12V secondaries. The output transistors were MJ9001 or something (don't have it with me).

The construction details were great. Really good pots, all elna caps, nice case with heatsinks I plan to use. The circuit board on the other hand looked on the cheap side. Heat during the years of operation had warped the traces and bubbled the protective layer in multiple spots.

I'm wandering what I can use the trafo for?
 
#12
scored one of these yesterday...

for AUD20 at the Blacktown markets. Apparently one channel isn't working, but the case (build like the proverbial brick dunny), transformer & heatsinks would have cost a lot more than $20 new...
bi-amping here I come...
Pete McK
 
#13
As I recall, there were two amps, the cheaper one made by Cambridge Audio and the better one made by Yamaha.

The cheaper one was still available here (as a Cambridge) until about four years ago.

I just missed a 4000 on eBay, was going to use it together with my Sonab 75S turntable. Nostalgia rather than sound quality.
 
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