Colorsound Power boost noise issue

Michael, The PCB has been sent today, it's been sent special Delivery so you should get it tomorrow before 13:00.

The soldering is not good after having another look at it, especially around the transistors.... This is down to the swapping out of components etc. probably needs trashing now and starting again.... See what you think

Andy

Michael, as a heads up.... When you get the board check the 22uf cap between the emmiter of Q1 and pin 1 of the volume pot.... This might be the root cause, or something to do with it.

I just soldered this into another board and when i touch the volume pot i hear slight motor boating, but not when i DON'T touch it... It didn't happen before i soldered this cap in.

Hello Andy,

I just received your board and connected it up with a lab power supply, signal generator and scope - it seemed to work fine.

So I connected it up with batteries, signal generator and Chord practice amp - still fine.

I don't have a guitar at work so I'll bring one in tomorrow.

I'm not sure if this is good news or bad !

What power supply were you using.

MK

Batteries.... I was using batteries

It's fine???

Now, that's weird... It was motor boating without a guitar, you heard the video!! With the volume right up it sounded horrid.

This may sound a bit pedantic but I'm struggling to pin down differences, what kind of batteries ?

The ones I used were Duracell  "Industrial" alkaline batteries straight out of the box. I'm wondering if power source impedance matters (I'll test for that soon.)

MK

Ok, the batteries were brand new "Energizer" batteries. I do have a 18v DC power supply to that I could try.

The board I have here is running perfectly... With no issues.

Energizers should be OK - I'll still explore the possibility.

I probably won't be able to do much on until the weekend now - but you might get lucky if real work hits a boring patch.

MK

Many thanks for taking the time..... i'm interested in why this is happening even more now.

I connected your board up to a guitar and amplifier running off the new Duracell batteries - no problems and certainly no motorboat noise.

I then tried a 100R resistor in series with the batteries and still no problems.

Did you test the board out of the metal box - I'm wondering if something might have been shorting to the box, or possibly a problem with the switch wiring.

I can't think of anything else useful I can do with it  - so let me know if you can think of any other tests - otherwise I'll send it back to you.

MK

Hi Michael,

Is there a chance that the board is overdriving Andy's guitar amp and the guitar amp is actually what is causing the motorboating?

John

It's not very likely because Andy's recording shows that the noise can occur when there is no other signal, and with the guitar volume control turned right down.

MK

It's not very likely because Andy's recording shows that the noise can occur when there is no other signal, and with the guitar volume control turned right down.

MK

This is very strange indeed.... Could it be some kind of interference peculiar to my house?

For the record, i tested the board mostly out of the enclosure, as you could see in the videos.... I have built another board and that is ok, (although the motor boating is there very faintly when on the highest gain setting)

I'm at a loss............. The evidence was there.... So what could it be?

Send it back.... i'm going to take it to a friends house and try it through his valve amp, and see if it happens there..... I'll report back findings.

One question Michael.... What do you hear when the pedal is at full gain..... as that is when it seems to be at its worse?

Hello Andy,

It's all OK at full gain, quite a bit of hum from the cheapo guitar but no other problems.

We've got a digital audio recorder at home so, if you are not in a rush to get it back I'll bring the recorder in and make some recordings for you.

MK

A recording would be great... Not that i disbelieve you at all... Just want to hear what you hear.

now the second question, could it be the guitar wiring?? This guitar wasn't wired by me, the pickguard was bought ready assembled, all i had to do was wire the jack socket and attach the earth wire to the tremolo claw. This is the assembly that I bought about 7 years ago

http://www.stratcat.biz/4035.shtml

All the  components are of the highest quality possible, and have not caused me any issues before. However, that's not to say something may have degraded or come loose in the last 7 years.... saying that It can't be the guitar as I've experienced the noise without having the guitar plugged in.... 

I'd be very surprised if the guitar made a difference - on any I've seen the volume control shorts the signal to ground at minimum setting and that's going to leave you with just the cable impedance shorting the input of the pedal - and your board seems quite happy with that.

MK

i didn't think it could be the guitar...... Clutching at straws now for an explanation