SK61 questions

HiFi-Kompaktgeräte wie Studio, Audio, Cockpit etc. und PC 1 integral
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bulba
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SK61 questions

#1 Beitrag von bulba » 29.05.2013, 01:34

Hallo ,
At last I've got SnowWhiteCoffin.
It's not perfect (without plate, without pickup system, broken acrylglass, need some carpentry) but when I pluged it as amplifier (Logitech Squeezebox + L320), it sounds great!
Great stereo effect - after a little funny balancing. :lol:

Some questions:
- What speaker impedance I shoud use 4 or 8 ohm?
- What is a switch on the back (neat speakers sockets) for?
- What is the double needle N-M in Elac KRS 102 for? ( 78rpm?)
- Where can I buy original plate (I've temporarily lent it from my PC3SV)?
- What was original surface of arm metal elements - chrome or polished? My are rusted.

As a tuner sound was distorted a little.(tube or elko?) :cry:
Bild
how to do a screen shot

Regards,
Woytek
More than hundred pieces with green power button ...

wickerge
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#2 Beitrag von wickerge » 29.05.2013, 10:27

Hello Woytek,
needle position N -> normal is for 78 rpm,
needle position M -> micro groove (Microrille) is for 33 & 45 rpm.

The handle bar is coated somehow, but is not chrome. Maybe you can clean it using fine steel wool (000) and a cleaner with strong detergents.
For a replacement plate you probably have to look in Ebay, or someone in the forum has a spare one.

Best Regards
Gerhard

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bulba
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#3 Beitrag von bulba » 29.05.2013, 19:59

Hi,
Thanks for sugestion, steel wool is OK. I've forgoten about this useful tool.

I'm still intrigued by this little swich on the back side(?)

And one more thing:
The amp is driven by two different tubes EL84 and EL95 on each channel.
I suppose its for compensate volume of L1 and onboard speaker.
But when I use two external speakers (the same type) balance is shifted on the left side.

Is it possible to remake it to use the same tubes on each channel to get normal balance?
Maybe someone allready made this?

Regards
Woytek
More than hundred pieces with green power button ...

braunfreund
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#4 Beitrag von braunfreund » 29.05.2013, 20:50

Hi Woytek,

the SK61 is equipped with two different amplifiers: one for full range band (bass/mid/high with EL84 output tube and one only for mid and high range with the smaller EL95 output tube.
By connecting a second loudspeaker to the other channel, stereo reproduction could be made. The bass frequencies were transmitted only over one channel since it was claimed that they cannot be located in the room (similar to today's subwoofer/ 2x mid/ high speaker systems). A curious solution from the early days of stereo.
The switch at the back is named "Seitenwahl", that means "side selector". Depending on how the SK61 is placed at the left or right side of the room (and the additional speaker , of course, at the other side), it could be selected by the switch which of both speakers gets the fullrange signal. But, as a side effect, the two channels from the record player can also be reversed, that means the record's right channel comes out of the left speaker.

The (first stereo) model before, SK6, has two EL95 output tubes, but the remaining components around are made so that also only one channel transmits the fullrange sound. I have tried to modify the other channel so that it also transmits fullrange (changing some capacitors and inserting the bigger output transformer from an SK5). But this would not work well, the amplifiers then tended to oscillations and, for whatever reason, did not sound equal. So this was not the right solution.

In the SK61, Braun brought back the EL84 output stage to get the more powerful sound (4 watts) as at the older mono versions. The second channel was reduced to an "auxiliary" channel with only 2 watts.
So, you would not get equal fullrange transmission on both channels as with a "real" stereo system. The excursion to stereophony was not successful, and the following version SK55 was a mono system again similar to the old SK5.

Best regards,

Lutz

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bulba
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#5 Beitrag von bulba » 30.05.2013, 23:04

Hi,
Thanks Lutz for this amazing story. As I expected ,SnowWhite is something special!
I'll do not make any changes. All I have to do is complete plate and pick-up system and enjoy this early stereo sound.

Regards
Woytek
More than hundred pieces with green power button ...

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