ADA Depot - A Forum To Support Users of ADA Amplification Gear
ADA Power Amps => Microtube 200 MT-200 => Topic started by: Lyates1987 on April 30, 2021, 10:50:31 AM
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So I recently got my hands on the MT200. It's not a bad amp at all, I was mainly in it for the 1U slot. both A and B channels seem to work fine but the Mono/Bridged channel is WAY quieter than running just the A or B channel. 200 watts at 8ohms, was definitely expecting it to be louder, not quieter. I'm gonna take a look at what's going on and report back but so far the plan is to blow out all the BS and do a reflow on the jack pcb and also give it a good dose of Deoxit. So far there doesn't seem to be any damage or blown caps/resistors etc. Haven't changed the tubes yet but thats on the list of shit to do as well. Just like any other amp, sounds great when cranked.
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Cool, strange it's quieter in bridge mode though :crazy:
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NICE!
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Hey BJ,
Sounds like you got a great deal on that one :thumb-up:
Harley 8)
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Thanks guys! So far I'm alright using just 1 channel but would like to get the bridged channel working right, unfortunately I didn't have time to work on it this weekend and still waiting fro more deoxit to come in the mail (forgot I was out!) but I'll report what I find so I can add some input regarding the bridged channel. Seems like that channel is rather finnicky based on what I've been reading.
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When you play in bridged mode, does everything sounds clean? I mean no distortion?
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When you play in bridged mode, does everything sounds clean? I mean no distortion?
Yes! after taking another good listen there is distortion! I tried to play harder with it turned up all the way and it almost sounds like it's trying to get way louder but can't quite do it.
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Could be that there's something wrong with the bridge mode circuit.
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Could be that there's something wrong with the bridge mode circuit.
Sounds like a not so solid connection somewhere, still trying to hunt it down but no clear visible signs. Multimeter time.
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Could be, in the bridged out jack is a switch that should open and in the A and B out jacks is a switch that should be closed in bridge mode.
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Could be, in the bridged out jack is a switch that should open and in the A and B out jacks is a switch that should be closed in bridge mode.
Is the switch you referring to the little silver thing sticking out at the bottom of the speaker out bridged jack?
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It's on the inside of the switch so can't really tell but it could be.
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Still having a hard time figuring out what's going on with the bridged channel. I want to start jiggling wires and do stuff like that while it's on but I'm kinda scared shitless to do that. I usually bias my own amps but I haven't done anything beyond that except for replacing 1 resistor on my jcm2000 but the amp was off of course. Think I might get a decent shock with this amp? The only reason I want to do this is because it almost sounds like a loose connection somewhere, like when you only have 1 side working on your stereo and you hear the other side working a little bit when jiggling the connections, but it's hard to find with the amp off. If I can audibly hear it get louder I can narrow down what is causing this, just don't want to get electrocuted.
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Why do you think it's a loose connection?
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Why do you think it's a loose connection?
It sounds like it wants to get loud but it's not getting all the juice like there's a cold solder. I'm just wanting to jiggle the wires connected to the jacks a little to see if it does anything or helps me find where the problem is.
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You can try but be very carefull there are some lethal voltages inside. But I don't think that's the problem but you can always try to rule it out. When you poke around get a plastic or wooden stick.
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You can try but be very carefull there are some lethal voltages inside. But I don't think that's the problem but you can always try to rule it out. When you poke around get a plastic or wooden stick.
So I'm thinking it's the mono input jack. Not seeing any issues with the bridged circuit. Funny thing, I accidentally left the speaker cable in the bridged jack after moving my input to channel A, turned it on and started playing and it actually sounded pretty good, actually slightly warmer than just going with both channel A jacks. I noticed what I had done about 5 minutes into playing. Played a little bit more. It seemed like it would get a little louder too. Thought that was odd but decided to go back to both A channel jacks.
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Just had a look at the schematic and from what I can see when nothing is plugged in all the pins of the mono input should be grounded.