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post #1 of 13 (permalink) Old 07-17-2006, 04:47 PM Thread Starter
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Old Boogie question

OK I need some advice with regards to my faithful old Boogie DC-5.

I've had this amp since college which is a LONG time ago and it's never let me down, but never needed revalving, it's only a practice amp as it sounds great at loud bedroom volumes and I've always had bigger amps for gigs.

Truth is I've not had a valve amp long enough to need revalving, I've changed them a lot (but kept the DC-5 as it sounds so good) so I don't know when that is!!!


Anyway, I was playing tonight and I started to get a large jump in volume, like someone adding a boost, no extra gain, just extra mids and volume. Is it my master volume that's got dusty (this amp is 10 years old) or do I need new valves?


Any advice appreciated
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post #2 of 13 (permalink) Old 07-17-2006, 05:21 PM
 
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Re: Old Boogie question

Hiya Jono

I also have a Boogie DC5!
I bought it secondhand about 5 years ago
It still has the original Mesa valves in it.

Recently, more through boredom than needing them, i decided to try some new valves - borrowed from a mate.
And none of them sounded a patch on the original - i dunno! maybe 10 year old originals. So i stuck with the originals!!!
And this thing has done gig after gig

But i did have to change my Master volume pot a few years back!

try switch cleaner first, then look at the valves

Max
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post #3 of 13 (permalink) Old 07-17-2006, 05:54 PM
 
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Re: Old Boogie question

I own an original "76" Boogie MK I..... yep, before there was a factory. She has been around a long time. I have had to replace all the tubes twice in her lifetime and have always gotten the tubes (valves) directly from Mesa Engineering. You need to clean all the pots out with a good contact cleaner like CRC brand, retry it to see if that helps. Then pull each tube (valve) and make sure all of the contacts are clean and making good contact. Make sure none are loose also. If the problem still exists you may have a preamp tube going south. Those were the first things that usually went bad on mine. I always replaced them all so as to have matched sets both in the amp and for spares. Hope this helps.... if not e-mail Mesa Engineering and they can tell you who to take your amp to for a thorough once over. If you replace any power tubes (valves).... you'll need to have her bias re set to match the new tubes which any good amp tech should be able to handle.

Last edited by jemplayer55; 07-17-2006 at 06:05 PM.
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post #4 of 13 (permalink) Old 07-17-2006, 06:28 PM
 
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Re: Old Boogie question

Just as a note, when using the contact cleaner (my friend swears by the CRC brand), make sure it gets into the pot, then turn it back and forth for like 30 seconds. Then spray some more for good measure and twist it some more

I was given a Roland Cube amp from the 80s because the volume would drop. I sprayed some of the CRC in and twisted the knob for a while and voila it worked. Has been going strong for 3 years since.

PS: er, also just remembered I had the volume drop out on my Mesa .22 twice. Once it was a flakey cable between my pedals, the other time one of the preamp tubes got a little loose.
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post #5 of 13 (permalink) Old 07-17-2006, 06:31 PM
 
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Re: Old Boogie question

the boogies run at a fixed bias , which for most amps prolongs tube life better then amps that need to be adjusted . Mesa has a coding system for tubes , certain tubes will give more output by running closer to thier ideal current .

mesa amps are a bit different then other amps in that it is ADVISED that if the amp is under heavy use to replace the power tubes around a year and a half and pre-amp tubes 3-4 years . Like i said some mesas run on the same tubes for years and never have problems. Some tubes start to crap out after one or two .

like everyone else said , get you some cleaner and spray the pots down with a little and see if that doesn't help your problem . If not then you may very well have a tube that is going bad , a full re-tube shouldn't cost much more then 60 or 70$ . If that doesn't solve the problem time to take it to your local amp tech for inspection .
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post #6 of 13 (permalink) Old 07-17-2006, 07:09 PM
 
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Re: Old Boogie question

Quote:
the boogies run at a fixed bias , which for most amps prolongs tube life better then amps that need to be adjusted . Mesa has a coding system for tubes , certain tubes will give more output by running closer to thier ideal current .

mesa amps are a bit different then other amps in that it is ADVISED that if the amp is under heavy use to replace the power tubes around a year and a half and pre-amp tubes 3-4 years . Like i said some mesas run on the same tubes for years and never have problems. Some tubes start to crap out after one or two .

like everyone else said , get you some cleaner and spray the pots down with a little and see if that doesn't help your problem . If not then you may very well have a tube that is going bad , a full re-tube shouldn't cost much more then 60 or 70$ . If that doesn't solve the problem time to take it to your local amp tech for inspection .
"j.arledge" is absolutely correct..... fixed bias! It's my Marshall's that require more babying. My Boogie needed the SPAX7A one time and the 12AT7 the last time, like I said, we just re-tubed her complete or I should say my tech did. He said you just pop them out... pop in the new ones. But be sure you get them from Mesa/Boogie. They match the sets for your amp. He also reminded me that it has been more than twice that they were all replaced. That would have been wishful thinking (twice).
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post #7 of 13 (permalink) Old 07-17-2006, 07:39 PM
 
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Re: Old Boogie question

There's also a company called JJs tubes - don't quite know where, but a lot of the guys on the TriAxis forum absolutely swear by them.

My local amp guy, who I trust completely, having seen his work for almost twenty years informed me that 6L6 tubes are pretty robust, and you can pretty much swap any brand for any other, and not get too excited about buying matched pairs - hence my 2:90 Power Amp has 7 Groove Tubes and one Fender output tube - had the amp running for four years without incident so far...........

Your issue does sound more like a poor connection than a dying valve however - so follow the advice above before delving into re-tubing - as CRC can leave an oily residue which may collect dust, some techs recommend spraying pots and connectors with a freon type cleaner to remove the CRC residue after cleaning - I've cleaned things with and without using freon afterwards, and I can't honestly say I have noticed a difference.

Cheers

David
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post #8 of 13 (permalink) Old 07-18-2006, 12:37 PM Thread Starter
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Re: Old Boogie question

Thanks guys

I'll try some switch cleaner stuff and see how I go, updates to follow as and when

Cheers,
Jono
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post #9 of 13 (permalink) Old 07-18-2006, 11:36 PM
 
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Re: Old Boogie question

DeoxIT Pot & Switch Cleaner

StewMac is a bit pricey, but you can find deoxit cheaper at most online electronic supply store sites. I'd bet a new Jem that you'll find it on at least 90% of the most respected amp repair benches. The residue left after evaporation is a natural conductior lubricant and prolongs the life of pots by filling wear gaps in the pot wiper. "Your scratchy pots will be gone forever!"

I'm not trying to sound like a medicine show, but the difference between deoxit and pure solvent switch and contact cleaners is like night and day. When the generic stuff flushes the pot, all of the worn wiper micro-dust is washed away leaving micro gaps and a slightly weaker signal. The good stuff fills the gaps and improves signal purity.

If you already have some contact cleaner, use it. It will still clean the scratchy pots just fine. Order some deoxit, and re-spray when it arrives. If you still have any of your high frequency hearing left, you'll notice an obvious difference.

~Scott
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post #10 of 13 (permalink) Old 07-19-2006, 06:19 PM
 
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Re: Old Boogie question

You know whats funny? I bought my DC-5 secondhand and it had all the original tubes. First I replace the 2 power tubes, an it was great. Then I decided to replace all the original 12AX's with their "top-grade" SPAX7.
Man did that suck!! I dont care what anyone says but they sounded like crap. For some reason or another the gain character was changed completely and not nearly as warm. So I put the originals back in, and I think it went back, but Im still not sure. I think my ears like to play games on me alot. It kinda sucks...

You mentioned it needing an AT7? That's odd. But not really. Usually 12AT's are for an amps' reverb or tremolo, which the amp has reverb, but both my amp and manual for it state that all 6 tubes are 12AX7's. Whats up with that??
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post #11 of 13 (permalink) Old 07-19-2006, 06:36 PM
 
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Re: Old Boogie question

12AT7 used for reverb in way older models (MKI)..... If I remember correctly.
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post #12 of 13 (permalink) Old 07-22-2006, 05:31 AM Thread Starter
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Re: Old Boogie question

I think we're good now guys, I actually just used the household vacuum cleaner and sucked all the dust out of the graphic EQ!!!

I played around with all the settings and then noticed how dirty the EQ had got and that the mid slider was about the frequency of my mystery boost!!!

I'll be kinder to my amps in future, cos I don't think anyting sounds as good as my DC-5
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post #13 of 13 (permalink) Old 07-22-2006, 04:35 PM
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Re: Old Boogie question

Old tubes aren't as loud, and sometimes are more middy, but they sound great to me I like my tubes better after a hundred hours of burn in.

Glad you got that straightened out!
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