TSL 3.x TWEAK trimmer value

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Pav
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TSL 3.x TWEAK trimmer value

Post by Pav » Mon Apr 08, 2019 3:43 pm

Tony, hi,
the horizontal trimmer TWEAK was 22K 3386G series
prior to the "3 and 3.1" build guide
The latest guide has 10K and uses F for 3.1 and G for 3.

Trouble is Im building the last ever of the v3 and singleton 10K G is proving tricky to find. //Edit 10k in stock Farnell el14.

why the change ? Can I use 22k ?
rgds Pav

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Re: TSL 3.x TWEAK trimmer value

Post by Synthbuilder » Mon Apr 08, 2019 4:25 pm

Pav wrote:why the change ? Can I use 22k ?
Yes, you can use 22K or 20K - indeed my prototype has 20K in there. But the 10K will be more likely to have the ideal trim position near its centre.

10K 3386G can be bought from Farnell: 9354778.

Alternatively, with the older issue 3 board you can fit the old style Piher trimmers. Rapid sell these, their part number: 51-9123. These are the ones shown on the project webpage:

Image

The Builder's Guide issue 3.1 has had various changes to component values. In building the 3.1 prototype, some eight years after I built the original issue 3 prototype shown above, I decided to have a little play around with the circuit again and have made several changes. None of them are critical but I prefer the sound of the new circuit.

Tony

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Post by Pav » Tue Apr 09, 2019 4:50 pm

Ok thanks.
rgds Pav

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Post by Pav » Mon Apr 22, 2019 12:15 pm

Hi again, I've now completed the TSL and happy with it but just wanted to record the other change of note was u1 and u4. I used tl072acp and not OPA 2134 chips specified. I could still order these ..though they are on the pricey side at around 4 quid inc vat. Do they make a significant improvement sonically?
rgds Pav

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Post by Synthbuilder » Mon Apr 22, 2019 4:11 pm

Pav wrote:Do they make a significant improvement sonically?
U4 is the one I'd recommend keeping the OPA2134 - mainly because it doesn't sound terrible when the output levels are near their maximum. The TL072 misbehaves (called phase reversal or latch up) when its inputs get too big in non inverting mode. That said if you don't drive the module hard with the resonance high then you can leave the TL072 in there. The classic LM1458 doesn't latch up either and it's dirt cheap. It may be worth a try.

U1 can be a TL072 or LF412 with no real issues. I didn't realise that the OPA2134 has increased in price so much.

Tony

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