H2O chorus/echo- not sure if it's broken or it's a feature!

[imaradiostar]

My brother plugged in the wrong power supply and cooked my Visual Sound H2O pedal. I replaced the shorted 1n400x diode with a 1n4002 and it seems to be working fine but it's been a year or more since I messed with it and there are two things that I don't remember/don't like. Perhaps it's how the pedal works normally, perhaps not.

1) When you move the "repeats" knob it scratches. After looking at the data sheet for the PT2395 and the pedal it would seem the 100k repeats pot is connected to between one of the PT2395 outputs (at 2.5 volts) and ground so there is DC across the pot (and a 4.7k resistor at the CW end). I don't remember it scratching before- so that's odd...

2) as you adjust the repeats knob toward max it seems like the repeats are getting darker and dirtier, like there is an impedance mismatch and the op-amp built into the PT2395 can't drive the load. I'm starting to wonder if something else was damaged but I'm don't want to waste time troubleshooting if it's normal operation for this pedal. With the repeats knob toward the middle everything seems to be fine. With the echo level cranked you hear a substantial change in the echo quality as you increase the repeats knob past about 2 o'clock.

I suppose I can call Visual Sound and ask (they've been very helpful in the past) but I thought I'd ask here to see if anyone else has noticed either of the same things.

The pedal doesn't sound bad necessarily- but I feel like it's not quite right somehow! I've been using a Nova Repeater and a few other delays so maybe I'm just not used to it. I just want it to be right before I put it all back together for good.

thanks,

Jamie

[Mark Hammer]

Wait. Any moment, I expect, RG Keen will show up to this thread....or you can call Dana at VS.

The scratchiness of the pot may be a result of some solder particles or other crud getting in the pot during the repair.

[imaradiostar]

Thanks Mark. I tried cleaning the pot with no improvement. I'd like to think my soldering is a little cleaner than that but who knows?

If you look at the AN for the PT2395 the output of the second filter on the chip should be hovering around 2.5 volts because it's internally referenced to 1/2 of VCC. There is no blocking cap between the pot and the output- only a 4.7k resistor. From this there is always around 2 volts DC across the pot. I'd imagine I'm missing something, of course.

I'm hoping RG will stop by because I feel bad calling VS with the whole "my toy is broken" line. They probably get that one a lot! They've been helpful in the past and I don't want to pick on them about something that may in truth be a quirk of the design.

jamie

[Mark Hammer]

Nah, if RG doesn't chime in, give them a call. I've visited the place and its a very helpful bunch of people. They work very hard to design things such that commonplace sources of complaint or malfunction occur less often, so every "battle story" is simply more data for the future.

I can't think of any deliberate basis for the effect on repeats that you note.

[R.G.]

You rang, sir?

It's not the way the pedal works normally. Something in there is either damaged or dying. In particular, crackle is never OK, and none of our pedals do it normally. The repeats do lose a little treble on each repeat, but do not get dirtier by design. It is possible that if it gets to where the repeats never die out, they actually build up and overload the signal stages in a fully working one, depending on the parts tolerance, as "infinite repeats" equals "self oscillation". The opamps are not overloaded by design; I'm sure of that one.

The H2O should not be damaged by reverse polarity, so if it was fried, I'm guessing that it may have plugged into an AC power source. The fact that the polarity replacement diode fried suggests this, anyway. If so, it was caught before things went really postal. We have had pedals in for service where the PCB under the protection diode was charred black from the heat and every IC and electro cap was dead.

I think Mark has it right - call up Visual Sound, talk to Dana. PM me if that's not helpful; but I think it will be.

As a side note, it is getting difficult to get some of the parts in the H2O in quantity. We'll manufacture it as long as we can because we get people calling in demanding yet another unit, but at some point we won't be able to do this. This was one of the reasons for the introduction of the Dual Tap Delay. So do contact Visual Sound before repair parts can get hard to find.

[imaradiostar]

Thanks for getting back to me RG. I talked to Dana last night and he said he was unsure of certain things and he'd have you contact me.

I'm pretty sure my brother plugged in a Line 6 modeler power supply (9VAC?) judging by the supplies I'd given him and the resulting damage to the board. I'd been using the H2O with a home-made regulated supply for a long time with no issues. I think it was a design from your web site, in fact- working fine since about 2003. When he told me it died I was surprised till I saw my Line 6 delay and filter modeler were there as well. All of the other effects on my home made supply are fine so I'm pretty certain it's not the issue.

The repeats pot connects between ground and one of the PT2395 outputs (which should be at 2.5 volts) with no blocking cap in-between. Isn't that a recipe for a scratchy pot? Perhaps I'm missing something.

Surprisingly the chorus side seems to work fine. I guess I'll look for a dead op-amp or bad cap downstream from the repeats control. I guess I'm lucky that all the other chips are good. An op-amp is a cheap and easy part to replace!

While I've got it apart I intend to mod it for self-oscillation and replace the delay lowpass resistor (2.2k) with a pot. Would you use a 5k or 10k in that position?

thanks again!

jamie

[Mark Hammer]

This is, incidentally, why so many major manufacturers will include some statement that "You MUST use our XYZ adaptor". Even though it is probably a nuisance, and not a money-maker for them to produce and sell the adaptor, it is an even bigger headache to have to explain all the parameters of a suitable power supply such that EVERY purchaser thoroughly understands what they can and can't use, and provide service for all those cases where the purchaser either didn't read, or didn't grasp or didn't follow up on the advisory.

Trouble is, there is very inconsistent standardization of external power. It would be one thing if pedals that required 18V used a different plug than ones using 9v, if devices using AC and providing their own onboard regulation used different plugs than those where they expect regulated DC, if those using outside positive had a different plug/jack than those using outside negative. But they don't. All too often, they all use the same damn 2.1mm barrel jack, and if the user is not paying attention, or doesn't understand, trouble ensues. Too much standardization of plugs/jacks, and too little standardization of power supplies/requirements.

[R.G.]

... and he'd have you contact me...

Tried to PM you, your PM box is full and won't take any more messages. Drop me a PM with your email address, if you would.

This is, incidentally, why so many major manufacturers will include some statement that "You MUST use our XYZ adaptor". Even though it is probably a nuisance, and not a money-maker for them to produce and sell the adaptor, it is an even bigger headache to have to explain all the parameters of a suitable power supply such that EVERY purchaser thoroughly understands what they can and can't use, and provide service for all those cases where the purchaser either didn't read, or didn't grasp or didn't follow up on the advisory.

Dead correct.

All too often, they all use the same damn 2.1mm barrel jack

Since we make both effects and our own power adapter, we had to address this head on. The Visual Sound pedals until the V2 (cast aluminum boxes) were vulnerable to the AC adapter stuff. In all V2 (and now the V3, with the Dual Tap Delay) pedals, VS pedals are immune to the AC power supply death. We got tired of both the explaining and the repairs.

We now test all pedal designs by plugging in both reverse polarity supplies and AC supplies, and ensure they live through it. The 2.1mm/5.5mm barrel plug is too pervasive, and there isn't any good solution to third parties putting this on as a termination. I recommend getting a can of the "Plasti-Dip" colored tool handle dip and painting all the AC plugs on pedalboards yellow or purple or striped or SOMETHING that makes them noticeable. That at least means you have to ignore screaming colors to get it wrong.

[imaradiostar]

I recommend getting a can of the "Plasti-Dip" colored tool handle dip and painting all the AC plugs on pedalboards yellow or purple or striped or SOMETHING that makes them noticeable. That at least means you have to ignore screaming colors to get it wrong.

That's a fabulous idea- I'll have to place a McMaster order for some and try it. I wonder if Small Bear or the like could have colored plastic plugs and jacks made to implement this solution. If only there was someone here with pull at a major guitar effect company that could implement such a thing!?

I like that some pedals are multi-supply friendly. If it weren't for the expense I'd use litte V-infinity DC-DC modules on my pedals with a diode and cap in series with the jack so they could accept just about any power adapter.

Thanks for the tip on my inbox- I cleared some space.

Thanks for the tip on purchasing spares as well. I've noticed PT2395's and PT2399's have gotten hard to find. I should probably buy some while they're still available.

Jamie

[Steve Conner]

The little isolated DC-DC converter modules are quite cheap. I was thinking of putting them in my old Trace Elliot compressor pedal (18V) and the Roland 606 I scored (9V, but self-destructs if asked to share supply with other pedals, due to the voltage regulator being in the negative rail)

At work, anything we design that uses a wall adapter runs off 12V with the centre pin positive. We use two sizes of wart, 2 amp and 5 amp, and the 5 amp one has the larger centre pin.

[imaradiostar]

So I poked and prodded- couldn't find a bad cap so i guess it's time to start replacing op-amps and other components. Sigh.

jamie