Fuzzy EA tremolo

LivingDeadPunk · February 25, 2005, 05:39:42 AM

Hi,

I've built the EA improved tremolo from GGG, it "works" but the output is a bit distorted and fuzzy especially if I plug it in a solid state amp, it sounds like a soft fuzz with a tremolo :twisted: two effects in one box :wink: I should be happy... actually I'm not; with a tube amp the distortion is less noticeable but still present.

I've used these transistors: Q1 2n3904, Q2 2n5088, Q3 & Q4 2n5457 as specified in the schematics.

I measured these voltages:
Q1
C 8v
B 8v
E 8v

Q2
G varies
S 9v
D 9v

Q3
C Varies
B 9v
E 9v

Q4
G 0v
S 5v
D 9v

It is my first pedal with more than one transistor and I'm a little lost, moreover I've never listened to a EA tremolo so I d'ont know what sound I should expect.

Is it normal to get a kind of small boost with this box? If so, what tremolo pedal should I build to get a very clean sound?

If not:

I use two guitars an Ibanez with Di Marzio pickups (humbuckers) and a Strat with Seymour Duncan pickups (humbuckers but single coil size), could the pickups be too hot for the box?

What should I change in the circuit to stop it overdriving?

Could it be a problem with the capacitor?

Should I replace some resistors with others with bigger values, and which ones?

maximee · February 25, 2005, 06:29:29 AM

are you sure you don't have your volume pot cranked on the EA?

I built mine and it sounds very nice and clean, although i can give my signal a very strong boost when i crank up the volume pot on my trem...

(don't you love the pulsating LED?

)

LivingDeadPunk · February 25, 2005, 07:07:03 AM

Well, when the volume is cranked the boost is stronger but even when it's set to, let say, 8 o'clock there is a small fuzzy boost.

I've used a 25k pot for volume, what's yours?

Do you use a tube or solid state amp?

I haven't tried the pulsating LED, it's only my third effect (after a Rangemaster and a Lofomofo) and I tried to build it as simple as possible, I think I'll do that later when everything works, because it DOES look cool.

maximee · February 25, 2005, 07:40:31 AM

Ok, as I said, mine is clean with Volume down one my Hiwatt tube amp as well as on others...also on my 15 watt practice piece-of-sh...

I don't remember what pot I used...currently I am at work, so I can't look it up right now. I don't think your problem is your volume pot though...

Sorry I can't help you for now...

LivingDeadPunk · February 25, 2005, 08:01:42 AM

oh, don't worry it does help, if yours stays clean even with a 15watt crappy practice amp and mine doesn't there is a problem, I need to find what it is now... And that should take some time.

maximee · February 25, 2005, 08:13:35 AM

soon the guys from "over-there" will wake up again...
they will help you for sure...

alors, Ã¡ plus tard... :wink:

LivingDeadPunk · February 25, 2005, 08:18:46 AM

I hope so

TschÃ¼s

new_winter · March 03, 2005, 05:14:18 PM

hey man... the trouble is:

2 resistor R3 & R4
change the value of R3 (82K) >>> 150K
change the value of R4 (15K) >>> 4K7

I did have the same trouble, I just change this Rs & super!!!

saludos

LivingDeadPunk · March 03, 2005, 05:20:12 PM

Ok gonna try this

Thank you mate

Transmogrifox · March 03, 2005, 05:31:16 PM

I know this is OT, but I like your signature LivingDeadPunk. Einstein had a lot more good to offer in wisdom about technology than all of his scientific progress. That is the way of human nature, is it not?

To your EA trem problem, sounds like you got the answer. It's just a gain/bias problem.

LivingDeadPunk · March 03, 2005, 05:43:24 PM

To Transmogrifox:

It is indeed. I was quite surprise to find that actually Einstein was a "philosopher" as well as a brilliant physicist, I've found a lot of quotes on the internet and even though most of them may be understood as jokes they convey much more than that; I may have a link with his most famous quotes in case you're interested.

LivingDeadPunk · March 03, 2005, 08:30:31 PM

Just checked and R3 and R4 are already 150K and 4K7, as specified on GGG layout, I don't understand what's going wrong :shock: ...
Should I lower R4 value and increase R3 ?

Transmogrifox · March 03, 2005, 10:22:51 PM

double check your connections and your build according to the schematic. It sounds to me from the voltages you provided that you have part of the circuit connected in reverse. you should see something close to 4.5 to 5.5 V on Q1 collector, a few volts on the base, and .7V less than that on the emitter. The JFET should be referenced to ground according to the schematic, so there's no reason there should be 9V on the source and drain...

so check what you're doing and make sure it's all consistent with the schematic.

LivingDeadPunk · March 06, 2005, 10:23:44 AM

I've decreasedd R4 (connected to Q1 collector) to 2.2k instead of 4.7k and replaced Q4 and it works perfectly

Thank you all for your help

onboard · March 06, 2005, 01:40:10 PM

Fantastic! Nice sounding trem, eh?

Incidentaly, I have the link to the original Electronics Australia article - is it ok to post it (the link, not the article)?

LivingDeadPunk · March 06, 2005, 02:57:14 PM

Very nice indeed, very Radiohead, with a delay it's awesome.

Go ahead, post the article, I'm looking forward to read it

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Fuzzy EA tremolo