SONTEC anyone?

godcity · 4th June 2008, 03:57 AM

I've got a Sontec mep-250c that's acting up. It seems like a small problem to me, but every tech I've taken it to is either stumped or doesn't want to work on it. I cornered burgess at AES and described it to him, but it didn't sound familiar to him either.

The problem is: The left channel high mid band sounds like it has an intermittent multiplier on it. With the gain set flat, if you, for example, set the frequency at 1k and start to increase the gain, it will sound like you're boosting 5k. Once you get up to about 5db of boost, it will "pop" back to the correct frequency. When you lower the gain, it will stay at the proper frequency for a while before eventually popping back to the multiplier.

I'm hoping to find someone who's experienced with these EQ's and willing to take a look at it.

email Godcity@aol.com if you're interested or know someone who might be.

Thanks!
Kurt

Led · 4th June 2008, 04:49 AM

Sounds like a dodgy multiplier switch that is shorting to the wrong contact. Could be dirt in there or it could be that it is simply worn out. Is it a switch on the Sontec for the multiplier? I don't have one so I don't know but it sounds like that sort of thing.

godcity · 4th June 2008, 04:31 PM

sounds like that but there are no multiplier switches on an mep250c. plus, all of the freq, gain, and Q controls are continuously variable, not stepped. the only switches on the entire unit are for bypass.

Quote:

Originally Posted by Led

Sounds like a dodgy multiplier switch that is shorting to the wrong contact. Could be dirt in there or it could be that it is simply worn out. Is it a switch on the Sontec for the multiplier? I don't have one so I don't know but it sounds like that sort of thing.

thermos · 5th June 2008, 06:46 PM

I can almost guarantee its a bad pot. The pot is either too dirty, or is losing connection, thus it doesn't know what its doing. It will make the op amps act up as well/ oscillate, pop, etc.

drpat · 6th June 2008, 08:35 AM

You may want to try re-flowing the solder for all of the pots. This cleared up the same type of symptoms that you are talking about with my 250B.

Wavebourn · 6th June 2008, 09:29 AM

The problem is, the frequency goes up, while in case of bad contact in the pot it should go down.

Some bug made a nest there?

thermos · 7th June 2008, 05:19 AM

Quote:

Originally Posted by drpat

You may want to try re-flowing the solder for all of the pots. This cleared up the same type of symptoms that you are talking about with my 250B.

250 B? I've never seen one of those. Care to show a pic?

drpat · 10th June 2008, 04:25 PM

music friend · 12th June 2008, 04:12 AM

Wow! Having never seen this model before, I never knew the GML 8200 borrowed the look of Sontec that closely.

thenoiseflower · 12th June 2008, 11:06 PM

+ 3 for dirty or damaged pot.
the signal stays present and clean, just takes a second for it to take effect?
I/ve actually experienced what I though was this once with a GML EQ. From what I understand it was fixed with a replacement Freq/Q pot.

Have you asked Rob Lohr?
This is Joe one of his guys, the 2 mix still sold?

godcity · 13th June 2008, 05:08 AM

hi joe,
yeah, rob suggested i contact GML. GML didn't know and didn't have any good leads on Sontec techs, so off to geekslutz i went.
what's this about a 2 mix?
-kurt

Quote:

Originally Posted by thenoiseflower

+ 3 for dirty or damaged pot.
the signal stays present and clean, just takes a second for it to take effect?
I/ve actually experienced what I though was this once with a GML EQ. From what I understand it was fixed with a replacement Freq/Q pot.

Have you asked Rob Lohr?
This is Joe one of his guys, the 2 mix still sold?

thenoiseflower · 13th June 2008, 03:06 PM

Should have re-checked spelling. Thought I typed "solid"

was meaning to say/ask if the 2 mix was still properly quiet since we left that morning.

------
IF GML couldn't help with your description of the issue, and the problem likely isn't the HS1000 op-amps (you aren't getting the usual !CRAZY! noises when operating with a bad op amp in the channel, which would be the

worst) I don't know what to say other than the best(only) thing to do may be touch all the solder joints to and on the affected pot and go from there... if its still acting silly.. I would avoid any further dicking around like the plague til' you had a Sontec "guy" that can/will work on it. good luck with that

.

thinking is - the next possible issue is debris got in the pot and maybe damaged the teeny little legs inside the pot, and if thats thats it, the whole micro surgery of a totally gone/unique part, makes techs VERY nervous. KWIM.

Someone besides Burgiss has to be able to look at these things by now, right

-

Oh this may be a bad lead, but, try calling IAN @ BoutiqueAudio - 818 564-4051

FWIW he knows a shit load of great techs.

godcity · 13th June 2008, 03:38 PM

2 mix is good!

doesn't look like it would be that hard to replace the concentric gain/Q pot if i can source the right one. also, this thing is full of TL071's (not socketed of course). there's probably something better out there now i could use. i'm no EE, but my solder skills are fine, so if someone tells me what to do, i can do it.

still interested in in those chandler limiters? PM or email me.

Quote:

Originally Posted by thenoiseflower

Should have re-checked spelling. Thought I typed "solid"

was meaning to say/ask if the 2 mix was still properly quiet since we left that morning.

------
IF GML couldn't help with your description of the issue, and the problem likely isn't the HS1000 op-amps (you aren't getting the usual !CRAZY! noises when operating with a bad op amp in the channel, which would be the

worst) I don't know what to say other than the best(only) thing to do may be touch all the solder joints to and on the affected pot and go from there... if its still acting silly.. I would avoid any further dicking around like the plague til' you had a Sontec "guy" that can/will work on it. good luck with that

.

thinking is - the next possible issue is debris got in the pot and maybe damaged the teeny little legs inside the pot, and if thats thats it, the whole micro surgery of a totally gone/unique part, makes techs VERY nervous. KWIM.

Someone besides Burgiss has to be able to look at these things by now, right

-

Oh this may be a bad lead, but, try calling IAN @ BoutiqueAudio - 818 564-4051

FWIW he knows a shit load of great techs.

Peter Simonsen · 14th June 2008, 08:12 PM

Quote:

Originally Posted by music friend

Wow! Having never seen this model before, I never knew the GML 8200 borrowed the look of Sontec that closely.

I would not say the GML 8200 "borrowed" the looks of the Sontec..I mean George more or less designed the sontec back then..so one could say he just continued the product line and the look after he started GML in 1982.

Kind regards

Peter

Paul Gold · 17th June 2008, 05:22 AM

The gain pot is a center tapped pot. They are impossible to find in small quantities. You can buy 100pcs from Alpha at about $15ea. The concentric frequency select and Q pot will be a dual reverse log on one shaft with a linear on the other. You might be able to get Omeg to make you some. They have a reasonable minimum order quantity.

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4th June 2008, 03:57 AM	#1
godcity Gear maniac Join Date: Dec 2003 Location: Salem, MA Posts: 285	SONTEC anyone? I've got a Sontec mep-250c that's acting up. It seems like a small problem to me, but every tech I've taken it to is either stumped or doesn't want to work on it. I cornered burgess at AES and described it to him, but it didn't sound familiar to him either. The problem is: The left channel high mid band sounds like it has an intermittent multiplier on it. With the gain set flat, if you, for example, set the frequency at 1k and start to increase the gain, it will sound like you're boosting 5k. Once you get up to about 5db of boost, it will "pop" back to the correct frequency. When you lower the gain, it will stay at the proper frequency for a while before eventually popping back to the multiplier. I'm hoping to find someone who's experienced with these EQ's and willing to take a look at it. email Godcity@aol.com if you're interested or know someone who might be. Thanks! Kurt __________________ kurt ballou http://members.aol.com/godcity

4th June 2008, 04:49 AM	#2
Led Lives for gear Join Date: Apr 2006 Location: Melbourne, Australia Posts: 1,772	Sounds like a dodgy multiplier switch that is shorting to the wrong contact. Could be dirt in there or it could be that it is simply worn out. Is it a switch on the Sontec for the multiplier? I don't have one so I don't know but it sounds like that sort of thing. __________________ "My voice has a built in extortion box" - recent vocalist I recorded...

6th June 2008, 09:29 AM	#6
Wavebourn Lives for gear Join Date: Aug 2006 Location: Walnut Creek, CA Posts: 892	The problem is, the frequency goes up, while in case of bad contact in the pot it should go down. Some bug made a nest there? __________________ Hybrid amplifiers combine errors of current amplification by transistors with errors of voltage amplification by tubes Anatoliy Lisovskiy Walnut Creek, CA, U.S.A. Wavebourn@yahoo.com http://Wavebourn.com

12th June 2008, 04:12 AM	#9
music friend Gear nut Join Date: Mar 2005 Location: Eagle Rock, California Posts: 117	Wow! Having never seen this model before, I never knew the GML 8200 borrowed the look of Sontec that closely. __________________ -CD

5th June 2008, 06:46 PM	#4
thermos Lives for gear Join Date: Jul 2004 Location: Los Angeles Posts: 1,785	I can almost guarantee its a bad pot. The pot is either too dirty, or is losing connection, thus it doesn't know what its doing. It will make the op amps act up as well/ oscillate, pop, etc.

6th June 2008, 08:35 AM	#5
drpat Gear Head Join Date: Mar 2005 Posts: 63	You may want to try re-flowing the solder for all of the pots. This cleared up the same type of symptoms that you are talking about with my 250B.

10th June 2008, 04:25 PM	#8
drpat Gear Head Join Date: Mar 2005 Posts: 63

12th June 2008, 11:06 PM	#10
thenoiseflower Lives for gear Join Date: Apr 2006 Location: Boston Posts: 1,018	+ 3 for dirty or damaged pot. the signal stays present and clean, just takes a second for it to take effect? I/ve actually experienced what I though was this once with a GML EQ. From what I understand it was fixed with a replacement Freq/Q pot. Have you asked Rob Lohr? This is Joe one of his guys, the 2 mix still sold? __________________ ---------------------------------------------------- "In an Expression of the Inexpressible..." "I just opened my back door and ran smack dab into a unicorn..." - NOT SO NEW "A lot of people these days are not music lovers - they just want to be famous which is a very different thing to what I grew up believing in..." - Shirley Manson "rules are for intersections" - UBK "Funny thing about the soapbox" - Slipperman.

13th June 2008, 03:06 PM	#12
thenoiseflower Lives for gear Join Date: Apr 2006 Location: Boston Posts: 1,018	Oops Should have re-checked spelling. Thought I typed "solid" was meaning to say/ask if the 2 mix was still properly quiet since we left that morning. ------ IF GML couldn't help with your description of the issue, and the problem likely isn't the HS1000 op-amps (you aren't getting the usual !CRAZY! noises when operating with a bad op amp in the channel, which would be the worst) I don't know what to say other than the best(only) thing to do may be touch all the solder joints to and on the affected pot and go from there... if its still acting silly.. I would avoid any further dicking around like the plague til' you had a Sontec "guy" that can/will work on it. good luck with that . thinking is - the next possible issue is debris got in the pot and maybe damaged the teeny little legs inside the pot, and if thats thats it, the whole micro surgery of a totally gone/unique part, makes techs VERY nervous. KWIM. Someone besides Burgiss has to be able to look at these things by now, right - Oh this may be a bad lead, but, try calling IAN @ BoutiqueAudio - 818 564-4051 FWIW he knows a shit load of great techs. __________________ ---------------------------------------------------- "In an Expression of the Inexpressible..." "I just opened my back door and ran smack dab into a unicorn..." - NOT SO NEW "A lot of people these days are not music lovers - they just want to be famous which is a very different thing to what I grew up believing in..." - Shirley Manson "rules are for intersections" - UBK "Funny thing about the soapbox" - Slipperman.

17th June 2008, 05:22 AM	#15
Paul Gold Gear addict Join Date: Jan 2003 Location: Brooklyn Posts: 417	The gain pot is a center tapped pot. They are impossible to find in small quantities. You can buy 100pcs from Alpha at about $15ea. The concentric frequency select and Q pot will be a dual reverse log on one shaft with a linear on the other. You might be able to get Omeg to make you some. They have a reasonable minimum order quantity. __________________ Paul Gold www.saltmastering.com most mixes that sound good usually look like a sort of puffy cloud - j ward

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