Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Booster)  [schematic]

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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby RnFR » 10 May 2011, 06:24

sorry didn't realize those values were missing. but, those caps look awfully similar to the .1, so I'm going to leave it marked for now. .1 is plenty big for bass back in the sixties before ultra low frequencies were popular. regarding the shop, I'd bet a simple email would work. if our situation was explained, I'd bet they would help. it's been done before, especially with these super rare units.
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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby Electric Warrior » 10 May 2011, 11:16

they do look similar, but still may be a different value. Some versions of the Zonk Machine had 0.47µF caps that look the same as well.
emailing them sure is worth a try...
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Postby Drzeus » 10 May 2011, 21:50

Hi EW,whats your provisional view on the out/in caps values,seperate from the t/b network?.I trust your decision.0.1uf for in cap,and 0.1uf for the out cap?Would this be a good starting point?
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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby Electric Warrior » 10 May 2011, 22:30

Out: pretty sure. For in it might be a good starting point. try your luck!
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Postby Drzeus » 10 May 2011, 23:35

I'll try 0.1uf on the input/out caps and report back
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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby Electric Warrior » 12 May 2011, 19:53

I emailed Solidbodyguitar, but they had already sold the unit.
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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby Drzeus » 23 May 2011, 06:15

I made a copy,and felt that 0.1uf was a bit big.I put a tropical fish 0.047uf in,and it sounded better to my ears.The 0.01uf are probably right,but the bass setting was a bit 'rumbly',even at low volume?I like it though.The pedals like a rangemaster/moles foot combo
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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby Electric Warrior » 23 May 2011, 12:19

0.047 could be correct. They definitely had some of these at hand, I know some Zonk Machines had them.
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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby joebonni » 25 Jul 2011, 01:08

ok this is Joe Bonni the guy that worked with Vintage Rob and Bassplayer...................

I have done so many changes and found that all this time i was right on the missing resistor its 100k thanks for that and you could use the oc71 and oc44 just about any will do but here at the caps that really work well ................... funny vintage rob had it all along hahahhahahahha ...............thats what happens when you use the wrong transistors hahahhahahahha .............. C1 on the Input cap is .022uf i use Mullard Tropical and C2 the Output cap is .01uf again Mullard Tropical this will give you the balanced sound you are looking for and it works as well on the 2n4041 .................... I like a switch for the Input cap to have .022uf and .010uf cause you get the brighter ritchie blackmore sound which is very over looked ............... on the GE version I like no Volume Control because in those days they played them wide open and used the guitar volume ................... on the silicone version i like the Volume Control because you get all the in between blackmore sounds ............. one of you guys here used the .1uf i/p and o/p if you use a bc107 you get like ritchies tape player its very close but you have to reverse everything .........................so the switch of the two different tones is cool but dont use a tone control its not good for that type of adjustment and there you have it like 4 years work ...........

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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby oh7hhi » 28 Jul 2011, 04:36

joebonni wrote: one of you guys here used the .1uf i/p and o/p if you use a bc107 you get like ritchies tape player its very close but you have to reverse everything .........................
Joe Bonni


Hi! What do you mean by "reversing everything"?
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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby Scruffie » 28 Jul 2011, 05:31

oh7hhi wrote:
joebonni wrote: one of you guys here used the .1uf i/p and o/p if you use a bc107 you get like ritchies tape player its very close but you have to reverse everything .........................
Joe Bonni


Hi! What do you mean by "reversing everything"?

BC107 is Silicon NPN, you'd have to reverse the power connections to make it negative ground and swap electrolytic orientation.

And Electric Warrior... problem with your schematic, the OC71 is shown as an NPN Symbol :mrgreen:
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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby Electric Warrior » 28 Jul 2011, 11:19

Dang, I keep forgetting to change the direction of the arrow. Image
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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby Drzeus » 28 Jul 2011, 20:19

I knew what you meant E/W!
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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby Electric Warrior » 29 Aug 2011, 15:02

Here's the corrected version:

selectatone.png
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Re: Hornby (Skewes, JHS) Selectatone T.B.2 (Treble/Bass Boos

Postby Electric Warrior » 02 Jun 2012, 13:10

New schematic: 100k is only in the treble path. Thanks Laundromat, for pointing it out to me!

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