Very strange D*A*M Pro MKII issue at a gig

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The Captain
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Re: Very strange D*A*M Pro MKII issue at a gig

Post by The Captain » Mon Jul 27, 2009 5:13 pm

How bizarre. Does sound like a temp issue to me, unless the speaker really did whack out the tone, though I can't say I've encountered that myself.

You could try pulling up/down the bias a teeny touch. The newer MKII's should be able to take a little more temperature fluctuations than the older fixed bias models. It was pretty damn not here (for the UK) when I made this last batch so maybe the bias was a hair higher than normal due to the heat over here.

If you wanna try the re-bias first off make a note of where the trimmer is currently set. You'll then need a multi meter, a cheap ass one will do. It wants to be set for volts DC. Insert a jack into the input socket, stick the red probe into one of the screw holes in the enclosure and the black one on the top side of the 8K2 resistor. Vintage units vary a fair bit, anywhere from 7.5-9.1 volts. Maybe try around 8 if you wanna play it safe. Different transistor configurations will like different voltages too. This copper unit sounded at it best at 7.5 and still had a little play either side should it get too hot.

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You can also do it by ear, which is much more fun. Get the MKII running into a clean amp at reasonable volume. Set the Level full and the Attack totally off. Roll your guitars volume control back a wee bit, about 7-8 if you have a Strat. The tone here should be pretty clear and clean, if you can hear some fuzzy artefacts then inch the trimmer over to the left until they disperse. If you then crank the Attack and pull up your guitars volume you'll also have maximum sustain from the unit, that too should give a little play on any temperature fluctuations.
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1bottlerocket
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Re: Very strange D*A*M Pro MKII issue at a gig

Post by 1bottlerocket » Mon Jul 27, 2009 6:11 pm

I had the same thing happen with another pedal, non-D*A*M, and I ended up switching to an Analogman Sun Face. THat little bias knob on the top comes in very handy in those situations.
Never argue with an idiot, they bring you down to their level and beat you with experience
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controller700
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Re: Very strange D*A*M Pro MKII issue at a gig

Post by controller700 » Mon Jul 27, 2009 6:57 pm

Yes! My selfmade (BYOC) Tonebender MKII (3xOC75) has a similar behaviour! Sounds much better/usable on cold days.

Let´s take the Clapton trick a step further:
Buy a power supply which can deliver 12V DC, like the Burkey Flatliner,
get one of these litte car-fridges (needs 12V), add true bypass and input/output to the fridge and
leave the MKII in it! :hihi:
That would look amazing on the pedalboard.

Image
I don't know what the hell it does, but it's definitely doing it!!
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Richard Groff
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Re: Very strange D*A*M Pro MKII issue at a gig

Post by Richard Groff » Mon Jul 27, 2009 7:14 pm

The Captain wrote:How bizarre. Does sound like a temp issue to me, unless the speaker really did whack out the tone, though I can't say I've encountered that myself.
Thanks Captain. I do some more experimenting to see if there is anything I can do to work it out.

I guess its pretty clear that these pedals were designed in pre-Global Warming England and not Global Warming NYC Summer!

:choke: :doh: :errr: :doh: :choke:

It was 80 degrees at midnight and about 70% humidity, so I guess the temp never got cool enough after being cooked in the car for a bit.
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1bottlerocket
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Re: Very strange D*A*M Pro MKII issue at a gig

Post by 1bottlerocket » Mon Jul 27, 2009 7:20 pm

From what I read, 70º F is about all those germaniums can take before crapping out.
Never argue with an idiot, they bring you down to their level and beat you with experience
-Garfunk M. Rafferty
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For all things stomp: http://www.effectsdatabase.com/
Big Muff History Page: http://bigmuffpage.com/
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Richard Groff
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Re: Very strange D*A*M Pro MKII issue at a gig

Post by Richard Groff » Mon Jul 27, 2009 7:54 pm

1bottlerocket wrote:From what I read, 70º F is about all those germaniums can take before crapping out.
:doh:
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Bobby DEE
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Re: Very strange D*A*M Pro MKII issue at a gig

Post by Bobby DEE » Mon Jul 27, 2009 10:14 pm

TEMPERATURE can play HELL with fuzzes, especially germanium based fuzzes.

silicon transistors replaced germanium models, as they are much more stable and resistant to temp variation.

at outdoor gigs, and gigs where stage lighting or other things make it HOT.....it's gonna go bananas.

you almost need to carry a cooler, with some nice frosty beverages, so you can put your fuzz in there and let it cool down :party:
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Creepyfingers
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Re: Very strange D*A*M Pro MKII issue at a gig

Post by Creepyfingers » Mon Jul 27, 2009 11:15 pm

I would imagine in a club that stage lighting could be a big culprit in messing with the bias of pedals. Even if the room seems to be normal temperature. Those lights heat up whatever they're pointed at. If you pedal was somewhere that a stage light could beat down on it for a couple minutes that could have been the cause. I know a lot of times when breaking down gear that pedals are hot to the touch from stage lights. Especially if you are singing into a mic and they point them directly on you.

--Brad
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Bobby DEE
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Re: Very strange D*A*M Pro MKII issue at a gig

Post by Bobby DEE » Tue Jul 28, 2009 12:07 am

Creepyfingers wrote:I would imagine in a club that stage lighting could be a big culprit in messing with the bias of pedals. Even if the room seems to be normal temperature. Those lights heat up whatever they're pointed at. If you pedal was somewhere that a stage light could beat down on it for a couple minutes that could have been the cause. I know a lot of times when breaking down gear that pedals are hot to the touch from stage lights. Especially if you are singing into a mic and they point them directly on you.

--Brad
our drummer in my 80s band started to get a BALD SPOT, because when he was up on the drum riser, his head was directly under our lighting truss, which was loaded with between 32 and 64 1000 watt par cans, depending on the gig.

luckily, today you can get those new LED based par cans, that do NOt heat up and don't draw so much juice.

but those old school 500 and 1000 watt PAR cans can REALLY generate some heat. :cthulhu2:
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1bottlerocket
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Re: Very strange D*A*M Pro MKII issue at a gig

Post by 1bottlerocket » Tue Jul 28, 2009 7:06 am

Here is what I am partially basing my 70º F number on:
"BIAS trim pot on...is used for keeping the fuzz happy at different temperatures, and with different or worn batteries...We factory set the SUNDIAL so the face is vertical at our shop temperature (70 degrees or so depending on if it's Winter or Summer!)...
So from reading this, I inferred that 70º F is around the temperature that germanium transistors like and the bias can be adjusted from there. On the Analogman version, that little Sun Dial knob comes in handy but if you don't have the bias knob handy and the temperature gets past the 70º F mark, one can infer that problems will arise.
Never argue with an idiot, they bring you down to their level and beat you with experience
-Garfunk M. Rafferty
_________________________________________
For all things stomp: http://www.effectsdatabase.com/
Big Muff History Page: http://bigmuffpage.com/
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