E A Tremolo build, how can I increase the depth?

[che47audio]

Hi there,

I recently built this E A tremolo:

http://tagboardeffects.blogspot.co.uk/2012/02/ea-tremolo-modified-rog.html?showComment=1394053689538#c5515869633617222442

I have tremolo!! I used a couple of equivalent transistors ( I used a 2n7000 and a BC550 in place of the BS170 and 2N5088) in this build purely because of availability. This is what caught me out. The pins were reversed so I had 2 0f the 3 transistors soldered in the wrong way around!!! No wonder it didn't work. Now I've got tremolo and a decent level/volume. Really satisfied that I've built this and its working but I am disappointed with the lack of tremolo depth. I've used a 250k lin pot for the depth, I don't know what impact that has on effect depth but its not currently getting deep enough. Its currently (with the depth pot at 10 (100% on)) very mellow, barely cutting in to the dry signal, basically its max depth setting is what I would use as a subtle tremolo. What can I change or what do I need to review to get the depth control working properly?

Thanks

Chris

[armdnrdy]

I would say that you have some other issue if the effect is subtle.

The depth pot 250KB is the correct value.

I would take voltages and troubleshoot your build. There should be EA Tremolo voltages on this site or online.

[GGBB]

I would say that you have some other issue if the effect is subtle.

+1

[che47audio]

Thanks for your reply.

I found this

http://www.diystompboxes.com/smfforum/index.php?topic=41829.0;prev_next=prev

Someone else who substituted the 2N5088 for something else. I think I'll try and get hold of one and se if it makes much difference.
The rate and volume clearly work. I did the LED rate mod with pulses with the rate speed, this also work fine. Its just the depth isn't cutting enough.

Thanks for the suggestions, I'll search around and look for some voltages to check against.

[GGBB]

Try reducing the 10K resistor.  This should increase depth, so if the BC550 is causing the problem it might just need to be biased differently than the 2n5088.  The LED could also be a problem if its voltage drop is too high - what type are you using?

[che47audio]

Oh ok I can definitely try changing the 10k resistor before I switch the transistor. What value would you recommend? I used one of these LEDs:

http://doctortweek.co.uk/shop/article_150/LED-Pure-Blue-3mm---Water-Clear-Lens%2C-Ulta-Bright.html?sessid=fpiLwc2MhS8lEclPNVV7zcp69c0vlK5V7Ak4rFmqjQU4gDpS4n4ftEXxCRymT9SS&shop_param=cid%3D53%26aid%3D150%26

no specs on there I'm afraid but I assume that these are fine.

Thanks again

[GGBB]

I'm only going from recollection of a post that I can't find right now, so I'm not completely sure whether or not this will do what I think it will, and I'm a little uncertain if it needs to go smaller or bigger.  So before doing any soldering, clip a 47K in parallel with it to bring the value down to about 8.2K and see if that does anything, then go from there.

[Digital Larry]

Do you have a schematic representing that layout? 

I recall looking at some EA trem schematics and thinking that the max gain variation was going to be about 12 dB, which is not going to put you into "stutter" territory.

[duck_arse]

http://www.diystompboxes.com/smfforum/index.php?topic=104454.0

another thread, tricky title, some depth stuff.

[GGBB]

Do you have a schematic representing that layout? 

It's the ROG version, which they've moved to the Home Wrecker site: http://www.home-wrecker.com/eatremolo.html.

[che47audio]

Sorted all working properly. Switched out the third cap for a 2n5088 and it worked straight away. `really chuffed with it. Thanks for all your help