Here's the stock version:
And with an added depth control:
Tuesday, January 6, 2015
Vox Repeat Percussion Tremolo
This cool little effect was originally housed in a small box that plugged directly into your amp (which you then plugged your guitar into) and later on some of Vox's higher end guitars. You'll need to track down an obsolete 2N2646 unijunction transistor for Q1, but they can be found on eBay or Small Bear. It produces a thumpy sounding tremolo that could be really useful if you're trying to cover The Who's "Baba O'Riley" and need to do the intro on guitar.
Here's the stock version:
Here's the stock version:
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Just built mine with all vintage metal can transistors from small bear, on etched pcb, with the depth control mod.
ReplyDeleteFreakin' love it. Thanks!
Sounds awesome! This will be my first clone.
ReplyDeleteHello everyone!!. Would anyone know how to add a pulsing LED to this tremolo (with depth control mod)? Something like Colorsound Tremolo which I did but did not work because the sound came out clean, with no effect at all. I tried several things but I gave up. Thanks for any reply.
ReplyDeleteHello people.
ReplyDeleteDid anyone know if I can use 2 x BC109, that is, a BC109 instead of BC108? Or what would be their equivalents or similar?
Thanks in advance.
You can try it. I think you need something lower gain in Q1. If you have a BC109B that might work better. Just socket and experiment. I think a 2N3904 would do well also for Q1.
DeleteOk and thank you very much. I will build it this weekend. I'll send you news after that ... I'm sorry for any misunderstanding because I'm from Brazil and my English isn't very good ... Thank you again.
ReplyDeleteHello again.
ReplyDeleteI did some shopping / research today and managed to buy the BC108 transistor in addition to the other components. My question now is whether I can replace the BC109 with a BC109C, as I only found this one.
As always, thanks in advance.
Yeah that should be fine.
DeleteHi.
ReplyDeleteAs I said earlier, I am going to build it this weekend. I'm feeling more confident now. Thank you very much for the reply and, mainly, for the attention.
Hi.
ReplyDeleteWell, I built it (option with depth control) and it works but I have the following problem at the extremes of the rate: the fastest speed is very slow. Really slow! Then I put a LED (between 9v, with a 10K resistor, and the emitter of Q1) and then the slowest speed is very fast. The LED flashes according to the set speed, which is something I really wanted. But as for the rate problems, could someone help me, please? Thanks.
Hello people.
ReplyDeleteI redid it and now it worked very well. Actually, I was using another layout, exchanging only the MPSA18 transistors for BC108 and BC109C. ("https://tagboardeffects.blogspot.com/2012/08/vox-repeat-percussion.html").
In this new construction I made 2 modifications:
1 - I replaced the 2.2K resistor with a 1.5K resistor, connecting a high brightness blue LED (+) with its other terminal (-) connected between base B2 of transistor Q1 and the 1K resistor (this is great as a flashing led!) and
2 - I changed the Rate potentiometer for a 50K Lin that slightly increased the effect region.
There is only one problem now: I get a very high "PLOP" when I turn the effect on but it doesn't happen when I turn it off.
Any idea what to do to resolve this? Thanks.
Add a 1M resistor from input to ground (called a pulldown resistor). Should help with the pop.
DeleteHello. I recently had the same problem with another tremolo that I set up ("http://www.generalguitargadgets.com/pdf/ggg_eat_mods.pdf" page 1). Talking to several people on this and other blogspots, some suggested the same to me, that is, a 1M resistor between input and ground, as well as between output and ground. They even suggested other values, bigger and smaller ... well, I made several attempts ranging from 100K to 2.2M, 3.3M ... and it didn't work. I gave up !!!!
ReplyDeleteI'm kind of upset that it will happen again now with this tremolo. Well, I did the same now on this tremolo and it didn't work either ... It's a good effect, with a lot of possible variations ...
These are (badly made) photos of my project at the moment (Tremolo, Fuzz - DeadAstronaut X Fuzz - and Wah - Colorsound Inductorless Wah).
"https://www.overpic.net/viewer.php?file=xa9wsrf33mrcf6c3nvb1f.jpg"
"https://www.overpic.net/viewer.php?file=xdklxz4rtrjhcr5jjmerx.jpg"
I thank you for the answers and help that have already been given to me, and also any further help, if possible, always remembering that my knowledge of electronics very little ... Thank you.
PS .: In Fuzz and Wah there is no "PLOP" ...
Hi.
ReplyDeleteI mean ("http://www.generalguitargadgets.com/pdf/ggg_eat_mods.pdf" page 2).
Another great layout! for anyone getting any ticking grounding the 10uf electrolytic and 33r resistor each separately to the output jack (ie the ground point) worked for me. I think its because both bases of the 2N2646 need grounding independently from the other components to stop them introducing ticking.
ReplyDeleteI also subbed the 22K for 15K to increase output and added a dpdt switch to select between 10uf/4.7uf for more speed options.
cheers again for the layout!
A very lovely vintage tremolo - thank you so much! Have fun with my demo: https://youtu.be/1c5oQGbDoeU
ReplyDeleteNew link to my demo, sorry: https://youtu.be/OnDf-82IFpc
ReplyDeletelast change… https://youtu.be/KKEYkdIu9hM
ReplyDelete