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Sansui SM-30

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tansu

Member
Joined 2014
Hello,
I have just registered to the site.
A few weeks ago I bought a Sansui SM-30 tube receiver. Overall it is in good shape but there are slight problems.
Does anyone have any experience with this receiver? I am looking for some parts like volume control unit, but i have no idea where to look. Previous owner said that, they changed the volume control from the original 500k to a new one 100k. And that makes me uncomfortable :)
Also I need some advice about a matching speaker.
And of course the specs
Regards
 
T

tansu

Member
Joined 2014
By the way here is the schematics for SM-30
If you can tell me where to look or who to talk about the right volume control pot to buy, I appreciate it very much.
Thanks
 

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jerluwoo

jerluwoo

Member
Joined 2006
AJT said:
good luck on your quest...that change to 100k from 500k is a step in the right direction imho...why? because todays sources have lower impedances than those of yesteryears'.....
Click to expand...

This would be fine if the source was only an external straight to the power amp, however, it has to be compatible with the internal pre and associated tone controls etc.

https://www.tubesandmore.com/products/R-VA2X500KA
 
T

tansu

Member
Joined 2014
AJT said:
good luck on your quest...that change to 100k from 500k is a step in the right direction imho...why? because todays sources have lower impedances than those of yesteryears'.....
Click to expand...

jerluwoo said:
This would be fine if the source was only an external straight to the power amp, however, it has to be compatible with the internal pre and associated tone controls etc.

https://www.tubesandmore.com/products/R-VA2X500KA
Click to expand...

Hi again and thanks for the answers.
Since I am totally noob I want to be sure on some issues. This potentiometer in the link, is this also a power switch? Because receiver starts from volume. Volume and power same switch.
And another issue, is this easy to install or a hard work? Because I dont have a good repairman. Can an average repair guy do this?
And one more, isn't it possible to find an original potentiometer for SM-30? If so, where should i look?
Here is a photo of the current 100k potentiometer which is installed by previous owner.
 

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directdriver

directdriver

Member
Joined 2005
AJT said:
change to 100k from 500k is a step in the right direction imho...why? because today's sources have lower impedances than those of yesteryears'
Click to expand...

The problem is that you have to account for the internal phono stage with no cathode follower so it cannot drive low impedance well, hence the 500K load. Also phono's output coupling cap is sized for 500K so changing to 100K the bass might be rolled off higher. However, if the user does not use the phono stage or uses an external phono stage then it should be okay.

- - - - - - - - - - - - - - - - -

By the way, I used to own a couple SM30 receivers before and it has a sweet sounding amp section. Very transparent and lively sound. Bass is adequate and tuneful. Overall sound is as good as any vintage 6BQ5 amp, except a few with bigger output transformers in the bass department. I only used the amp section and excluded the rest, phono, line, tuner, etc... so I couldn't judge the performance of those sections.
 
E

Eli Duttman

Member
Joined 2004
Tansu,

Look at this thread started by your countryman. If you convert the phono section to use the tweaked RCA setup, you don't have to worry about loading effects. :yes:

I routinely suggest that units of this "vintage" be modified to hard wire a single set of RCA jacks to the phono section and all the other I/Ps be configured for line level sources. If necessary, a low cost Lorlin CK1030 rotary switch can be installed as part of source selection modernization.

As for speakers, something with an honest low 90s sensitivity and a reasonably flat impedance curve will work well.
 
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