Author Topic: concert lead problem  (Read 5239 times)

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Offline DavidGiandiletti

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concert lead problem
« on: January 17, 2008, 03:39:02 pm »
just made my first sunn purchase, i got a silver face concert lead and 612s cabinet in pretty much perfect condition. When i first plugged it in the distortion wasn't working and the pots were really scratchy, i cleaned the pots with deoxit and got it working great except for the distort feature, when i turn it up it very, VERY subtly sounds a little more saturated but not anywhere near what i would even consider calling distortion. Any clues on what the problem could be or how expensive it would be to fix it? If its too much i would be happy just using the clean, this thing sounds great with pedals.

Thanks!

Offline DavidGiandiletti

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Re: concert lead problem
« Reply #1 on: January 17, 2008, 04:07:33 pm »
Also..as most of you know the cab is 6ohms would it be safe to run a 4 ohm tube head into it? I've heard with tube heads its better to have a perfect match.

Offline Isaac

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Re: concert lead problem
« Reply #2 on: January 17, 2008, 04:11:04 pm »
I wouldn't hesitate to run a tube head into the 612S, with the impedance set at either 4 or 8 ohms. Others' opinions may vary.
Isaac

Offline JoeArthur

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Re: concert lead problem
« Reply #3 on: January 17, 2008, 06:24:49 pm »
I wouldn't hesitate to run a tube head into the 612S, with the impedance set at either 4 or 8 ohms. Others' opinions may vary.

Yep, but my opinion doesn't vary.  :-D

The whole concept of "must have exact matched impedances" for tube amps is only for maximum power transfer. It's a delusion at best - some people realize that "matched" can only be nominal at best and that real impedances vary all over the map.  :-o :-o

Go for it and consider the choice of 4 or 8 ohms to be nothing more than an additional tone choice (i.e. if you do have a selection, set it to what sounds better to you).


Offline DavidGiandiletti

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Re: concert lead problem
« Reply #4 on: January 18, 2008, 12:39:43 am »
ok i've always heard that the impedance of the head should always be less but i guess when its only two ohms off its no big deal, I definately have some experimenting to do. any clue on the problem with the head?

Offline mckinnon audio

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Re: concert lead problem
« Reply #5 on: January 18, 2008, 08:51:19 am »
  Hi Dave,for your distortion(or lack of distortion) try this.Check the fet (field effect transistor) just before the distort. control.On the schematic it's Q-202,it's real # is 2N4304,and check the resistors and solder connections in the surrounding area.Hope this is of some help,Mel.

Offline JoeArthur

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Re: concert lead problem
« Reply #6 on: January 18, 2008, 10:34:42 am »
  Hi Dave,for your distortion(or lack of distortion) try this.Check the fet (field effect transistor) just before the distort. control.On the schematic it's Q-202,it's real # is 2N4304,and check the resistors and solder connections in the surrounding area.Hope this is of some help,Mel.

I just had a thought - are you using a footswitch for the distort? If not, that's your problem as the distort is "off" without the footswitch (or something like a shorting plug) completing the ground connection.

Offline DavidGiandiletti

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Re: concert lead problem
« Reply #7 on: January 18, 2008, 11:34:19 am »
Ok, I have the footswitch but havent tried it since i cleaned out the pots. If that doesnt work I'd like to take a look at the electronics but dont really know what I'm doing. Is there as much of a danger working with solid state amps as there is with tube amps?

Offline JoeArthur

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Re: concert lead problem
« Reply #8 on: January 18, 2008, 02:45:56 pm »
Ok, I have the footswitch but havent tried it since i cleaned out the pots. If that doesnt work I'd like to take a look at the electronics but dont really know what I'm doing. Is there as much of a danger working with solid state amps as there is with tube amps?

I could kill you with a solid state amp.  :-D :-D

Turn the power off and play it until you hear no more sound. Thankfully, solid state doesn't need heaters to work and this will drain the caps.

But as I said, the distort doesn't work without something making the connection to ground... like a footswitch. Conversely, the "boost" is always on without a footswitch to turn it off.

(edit) Oh, and of course the reverb is always on as well.
« Last Edit: January 19, 2008, 07:19:06 am by JoeArthur »