Matamps

Bacchus · Post by **Bacchus** » Thu Sep 26, 2013 3:25 pm

Phoned matamp. They're dead-on and pretty much told me the second hand 1224 is the one to go for. They even told me what to watch out for when buying one, what can go wrong or what might be worth negotiating on.

Concretebadger · Post by **Concretebadger** » Thu Sep 26, 2013 4:53 pm

BacchusPaul wrote:Phoned matamp. They're dead-on and pretty much told me the second hand 1224 is the one to go for. They even told me what to watch out for when buying one, what can go wrong or what might be worth negotiating on.

Great news. Opinions on the newer Matamps are few and far between, so I'd love to hear what you make of it. PICS PLZ, naturally.

Bacchus · Post by **Bacchus** » Thu Oct 10, 2013 9:00 pm

I can has:

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Concretebadger · Post by **Concretebadger** » Thu Oct 10, 2013 9:05 pm

BacchusPaul wrote:I can has:

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Congrats, you lucky, glorious bastard. Had chance to plug in and bring the ceiling down yet?

lorez · Post by **lorez** » Thu Oct 10, 2013 9:14 pm

Gratz Paul, that font always makes me week at the news

benecol · Post by **benecol** » Thu Oct 10, 2013 9:17 pm

Oh my...

Bacchus · Post by **Bacchus** » Thu Oct 10, 2013 10:36 pm

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It sounds unbelievably good. I'm chuffed to bits. There are no sounds that it isn't the best in the world at. So good, and switchable from 70 watts (or some other number suitably large) right down to 1 watt. From 4 valve class A/B to 1 valve class A, and all sorts of combinations in between. Apparently this one's fixed bias rather than cathode based but I think I'll phone the factory back up with the serial number and see if there's anything else on it that isn't standard.

Might have a dodgy valve in the power section. Today it didn't make a sound and one of them wasn't lighting, so I wiggled it a bit and it came good. Later on the same thing happened where it wouldn't light. I wiggled again and it did light but no sound. This confuses me. Valves tend to fail completely rather than in fits and starts, no?

tenderstems · Post by **tenderstems** » Thu Oct 10, 2013 10:44 pm

Could also be a number of other things. Tube socket might need retensioning, or it could be a loose or cold solder on the board caused by these things getting bumped or overheating.

I think these are all PCB now, so my bet would be a loose or cold solder joint.

Amps contain horrific voltages, so dont go poking in there if you dont feel comfortable. Maybe ask Matamp if there are known issues with this model.

Bacchus · Post by **Bacchus** » Tue Oct 15, 2013 12:17 pm

Took valve out, put it back in again and it works, but there were a few crackles, the amp was a bit buzzier than it had been but not unbearably so and it definitely isn't as loud.

This is more consistent with a valve on its way out, no?

NickS · Post by **NickS** » Tue Oct 15, 2013 12:47 pm

As tenderstems says, could be a bad solder joint on the socket, also could be a broken PCB track making intermittent contact. Can you try another tube first?

NickS · Post by **NickS** » Tue Oct 15, 2013 12:47 pm

Could also be a bad solder joint between the tube wires and pins, I've had that once.

Being not as loud might indicate low heater current, which would tie up with not lighting up at all sometimes.

Bacchus · Post by **Bacchus** » Tue Oct 15, 2013 1:14 pm

I'm afraid I don't have any spare tubes to swap. Is it safe to swap two tubes from the same pair, or would that cause problems bias-wise?

NickS · Post by **NickS** » Tue Oct 15, 2013 10:00 pm

No, swap them and see whether problem stays with the valve or the socket.

Bacchus · Post by **Bacchus** » Tue Oct 15, 2013 10:31 pm

Well, it's not the valve. Advice from here? If this is just a solder joint that wants reflowing I can probably do it myself, but if there is any more diagnosing to be done I'm not sure. Also not sure about poking about inside the amp.

Also, how much do amp folk cost?

othomas2 · Post by **othomas2** » Tue Oct 15, 2013 10:36 pm

My Classic 30 was making lightning and thunder like noises so bought a whole new valve set. Was better but still there... so put it down to valves warming up. More of a scuffling noise. Well as I went to sell it the other day... I gave it a good clean up with switch cleaner, cleaned the pots / sockets / valve pins etc but also read that this could be to do with speaker spade connections needing a clean. Anyways... I cleaned what I could and it was gone for good !! Might not be related but sometimes dust and dirt is the biggest issue with electrical things. I'm by no means an amp expert though !!!

NickS · Post by **NickS** » Tue Oct 15, 2013 11:16 pm

BacchusPaul wrote:Well, it's not the valve. Advice from here? If this is just a solder joint that wants reflowing I can probably do it myself, but if there is any more diagnosing to be done I'm not sure. Also not sure about poking about inside the amp.

Well, leave the amp switched off for a while (e.g. overnight), confirm no significant voltage left on the smoothing caps with a meter or by shorting to chassis with a bit of wire/screwdriver blade; the high voltage on those caps is what can kill you . Have a close look at the tracks around the valve base as well as the solder joints to the pins to see whether one of the pads is detached from the track. If it's been arcing you may see some discolouration. If this has happened you'll need to scrape off the solder resist on the track and bridge over the crack with a chunky bit of wire.

If you reckon it's the soldering on the valve base itself and you've got a desoldering pump or braid, remove as much solder as you can from the valve base and resolder with a flux-cored solder. If it's a dry joint there may have been some oxidation so flux helps remove the oxide. Apologies if this is teaching grandma to suck eggs.

Also, how much do amp folk cost?

Depends whether they do it as a full-time business or a hobby. I've fixed amps for a tenner. I doubt you'll find anything done in a shop under Â£40. Ask around, I know there's a guy round here who's known for very reasonable prices.

Bacchus · Post by **Bacchus** » Tue Oct 15, 2013 11:37 pm

Don't worry about the sucking eggs thing, this is all dead useful advice and I don't want to take anything for granted.

I'm assuming "smoothing caps" is British/European for "filter caps" the same way "electron valve" and "vacuum tube" are interchangeable? If so (and this had always been the bit that terrifies me) is there any easy way of telling which ones will kill you? other than physical size or rating? Or should I just short everything I can see to the radiator using a voltmeter to be sure?

EDIT: I also assume that "valve base" refers to the socket on the amp rather than the plastic sleeve on the valve itself containing the pins?

NickS · Post by **NickS** » Wed Oct 16, 2013 7:52 am

Don't short to the radiator, short to the chassis or to the other tag of the cap if it has only two (some old designs have multiple caps in one can, with multiple tags). Yeah, filter caps, reservoir caps, smoothing caps all mean the same thing. And yes, I meant the socket, that was ambiguous.

Treat any capacitor rated 50V or more with caution. Size is a good guide, I can't think of a design where the filter caps aren't the biggest, but there will also be one or two smaller ones in the preamp and possibly phase splitter sections where the valves normally run at a lower voltage, still in the 180 V - 250 V range. They'll be connected to the main filter caps through resistors so if you've just switched off an amp and discharged the main caps you can find they "mysteriously" charge up a bit from the other ones and it takes two or three goes to drop to a negligible value.

Concretebadger · Post by **Concretebadger** » Sat Oct 26, 2013 7:21 pm

@Paul: how did you get on with getting it fixed? Not frazzled yourself on a filter cap, I hope?

I was on the phone to Jeff this morning about the Mini Pro...boy, can that bloke talk! I think he gave me a run-down on amp tech for a full half hour with barely a word in edgeways before saying cheerio and seeing to another customer who was in the workshop at the time. He's like a West Yorkshire Steve Albini - he comes across as a bit gruff and opinionated at first, but he knows what he's talking about and will go out of his way to get you the sound you want (they'll give me a lift to the shop from Huddersfield if I let them know in advance, apparently).

I think I'll be paying a visit to t'mill next month - from what I heard today, a Matamp mini is exactly what I'm looking for.