ADA Depot - A Forum To Support Users of ADA Amplification Gear
ADA Power Amps => Microtube 200 MT-200 => Topic started by: Dante on March 12, 2021, 07:36:25 AM
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Yo! I'm about to start using my rack on a regular basis again :banana: and that means I'll be running through my MT-200; Microtube power amp. So, for those of us who have one, or those who are just interested in finding one, here are the answers to common questions about them.
Q: Can I run one side at a time?
A: Yes. The two sides are independent of each other
Q: If I run only one side, how many watts is it?
A: The manual says 100w at 4 ohms per side, somebody smarter than me can tell me what the rating is into 8 ohms or 16.
Q: Is it stereo??
A: Yes. Because the two channels are independent (as mentioned above)
Q: What kind of tubes should I run?
A: Oh boy. Whatever you like. It's a very subjective topic of much deliberation. I went with very clean, low noise 12ax7 tubes...not sure what brand. I didn't like tubes intended for high gain preamps. (just my taste, ymmv)
I have more...I'll update this post later, gotta run
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What are you going to do??? >:D >:D >:D
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Yo! I'm about to start using my rack on a regular basis again :banana: and that means I'll be running through my MT-200; Microtube power amp. So, for those of us who have one, or those who are just interested in finding one, here are the answers to common questions about them.
Q: Can I run one side at a time?
A: Yes. The two sides are independent of each other
Q: If I run only one side, how many watts is it?
A: The manual says 100w at 4 ohms per side, somebody smarter than me can tell me what the rating is into 8 ohms or 16.
Q: Is it stereo??
A: Yes. Because the two channels are independent (as mentioned above)
Q: What kind of tubes should I run?
A: Oh boy. Whatever you like. It's a very subjective topic of much deliberation. I went with very clean, low noise 12ax7 tubes...not sure what brand. I didn't like tubes intended for high gain preamps. (just my taste, ymmv)
I have more...I'll update this post later, gotta run
As an experiment I did one time with my MT-200, I used a pair of Fender branded high gain 12AX7's in it, and that seemed to produce a more prominent effect on the Presence control of the amp's tone.
Also, it should be noted that the manual states you can bridge the two channels of this amp to double the power into single channel speaker system. Personally speaking, and I may be completely wrong about this, but I wouldn't recommend it. Bridging both channels seems to bring about the failure of the power transistors on one side of the amp faster, usually the right channel.
Just my .02 cents
Harley 8)
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Thanks Harley :thumb-up:
Iperfungus; I am currently running bridged mono (200w) into my 150w/8ohm EV Force speaker. I don't get the volume of the amp above 12:00, usually closer to 10:00.
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I think I know why the B channel gets blown when it's in bridge mode. Problem is that the output of the B side is connected to the sleeve of the speaker jack. Most of these jacks are metal so if something is touching the jack that is grounded it can blow up the B channel. So best is to isolate the metal part of the jack.
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I think I know why the B channel gets blown when it's in bridge mode. Problem is that the output of the B side is connected to the sleeve of the speaker jack. Most of these jacks are metal so if something is touching the jack that is grounded it can blow up the B channel. So best is to isolate the metal part of the jack.
Does this also apply to the MT-100?
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Yes it does.
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The speaker jacks I've used for the cables I made have plastic sleeves, but the base,(where the barrel connects to it) is metal. I may have to use some heat shrink tubing over that to help insulate it.
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I think I better do that too - been running stereo lately
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You will only have this problem when running in bridge mode.
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So that must be the elusive cause I've been trying to figure out for all these years.
I really love how the Microtube 100's sound when they are bridged.
Harley 8)
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Is $200 shipped a fair offer on the MT-200 nowadays?
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Is $200 shipped a fair offer on the MT-200 nowadays?
If both channels are working and there's no issues, that doesn't sound like a bad deal. I would plan on a fresh pair of tubes though.
Harley 8)
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I'd be stoked to find one that cheap in working order. I'd expect to pay at least $250, maybe more for a clean one. That said, you're probably still better served changing tubes.
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I'd be stoked to find one that cheap in working order. I'd expect to pay at least $250, maybe more for a clean one. That said, you're probably still better served changing tubes.
Definitely changing tubes. Same guy I bought my MP1 from and the MP1 came through sounding great. It ended being $245 so not too bad. I saw a few recent sold listings for under 200 but I couldn't get the guy come down to that.
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IMHO if it's in good working order, $200 (incl. shipping) is a more than fair price.