LM13700N tip/recommendation

[Quirkey]

Not really a question but I have a strong tip/recommendation for anyone trying to build any circuit that uses LM13700N ICs (ie many phasers).

Build the CDXL Reissue Envelope Filter first and use it as a test circuit!

Previously I struggled in getting an AionFX Redshift/Whetstone phaser to work and one of the potential culprits was bad ICs but because there are 3 in that circuit it was very hard to test, and it also seemed like there might be other issues. I ended up buying a ton of LM13700s (12 to be exact) and could never get that PCB to work (I ended up scrapping it and harvesting its parts). I also tried breadboarding the test circuit outlined in the spec sheet but also couldn't get it to work (but unsure if it was my breadboarding or the ICs).

Last night I finished building the envelope filter circuit and it worked immediately. Running a looper through the circuit, it is VERY obvious if it is functional or not (If it QUACKS is it a DUCK?). I realized that this is a great way to test the ICs and went through all of the ones I had collected. Turns out 5 out of the 11 were complete duds - either did not make any noise or just loud buzzing. (The two I bought recently from Tayda did work FWIW).

Now, I have a great tester for future phaser/filter explorations and you should, too!

 

[mkstewartesq]

Turns out 5 out of the 11 were complete duds - either did not make any noise or just loud buzzing. (The two I bought recently from Tayda did work FWIW).

Now, I have a great tester for future phaser/filter explorations and you should, too!

Care to name the sources for the ICs that didn’t work? I just ordered some LM13700s but specifically avoided buying them from Tayda because anecdotal evidence about the quality of their chips seems to go all over the place.

Thanks,

Mike

 

[Quirkey]

Unfortunately, they all got mixed up so not sure which was which but some from Tayda, some from Jameco, and some from Amazon. Some of the older ones were from Tayda too so it might be chip by chip. Again - another reason to build a test circuit. I also got some of the newer SMD versions and PCB adapters but have not tested those yet.

 

[BuddytheReow]

I just got a small batch of em from Tayda. The one I tried worked for me

 

[DGWVI]

I've used Tayda's with no issues.

And the LM13700 I bought from MyColo have all worked fine

I've also been Using these NE5571s

 

[jimilee]

Care to name the sources for the ICs that didn’t work? I just ordered some LM13700s but specifically avoided buying them from Tayda because anecdotal evidence about the quality of their chips seems to go all over the place.

Thanks,

Mike

I’ve been getting mine from guitarpcb.com. He has sales all the time.

 

[Feral Feline]

Previously Barry wouldn't ship ICs north of the border (mail issues), however my last batch of LM13700 ICs made it to the GWN from him!
Huzzzahhh!!!

As JimiLee mentioned, GPCB has sales quite often and Barry pretty much guarantees the stuff he sells.

 

[Deperduci]

I may have to semi break down and do that.. or just breadboard the envelope board, I had aion sunstone work a few days afterAI just built it, left it lay for a few months using a mu-tron clone instead and now the sunstone has no effect, sound comes through, no modulation. think mine came from either SBP or AP in Tempe
And cabintech is out of the smd's....


Late edit, forgot I had an MBP flunkee/dod DD-25, does the same thing for bass that the 440/cdxl does for guitar

 

[mybud]

Not really a question but I have a strong tip/recommendation for anyone trying to build any circuit that uses LM13700N ICs (ie many phasers).

Build the CDXL Reissue Envelope Filter first and use it as a test circuit!

Previously I struggled in getting an AionFX Redshift/Whetstone phaser to work and one of the potential culprits was bad ICs but because there are 3 in that circuit it was very hard to test, and it also seemed like there might be other issues. I ended up buying a ton of LM13700s (12 to be exact) and could never get that PCB to work (I ended up scrapping it and harvesting its parts). I also tried breadboarding the test circuit outlined in the spec sheet but also couldn't get it to work (but unsure if it was my breadboarding or the ICs).

Last night I finished building the envelope filter circuit and it worked immediately. Running a looper through the circuit, it is VERY obvious if it is functional or not (If it QUACKS is it a DUCK?). I realized that this is a great way to test the ICs and went through all of the ones I had collected. Turns out 5 out of the 11 were complete duds - either did not make any noise or just loud buzzing. (The two I bought recently from Tayda did work FWIW).

Now, I have a great tester for future phaser/filter explorations and you should, too!

Great idea, @Quirkey. Something similar for 072s (that is, a circuit which uses no more than one at a time) has been on my mind for awhile. I've breadboarded a Fuzz Face test jig lately, helpful when trying to eliminate marginal or problematic geraniums. As below: