MT-200 FAQs

Dante · March 12, 2021, 07:36:25 AM

Yo! I'm about to start using my rack on a regular basis again

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

Iperfungus · March 20, 2021, 03:07:12 PM

What are you going to do??? >:D >:D >:D

Harley Hexxe · March 21, 2021, 04:48:28 AM

Quote from: Dante on March 12, 2021, 07:36:25 AM
Yo! I'm about to start using my rack on a regular basis again 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)

Dante · March 21, 2021, 10:30:43 AM

Thanks Harley

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.

MarshallJMP · March 22, 2021, 02:16:59 PM

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.

Harley Hexxe · March 22, 2021, 05:19:04 PM

Quote from: MarshallJMP on March 22, 2021, 02:16:59 PM
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?

MarshallJMP · March 23, 2021, 01:06:47 PM

Yes it does.

Harley Hexxe · March 23, 2021, 01:42:03 PM

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.

Dante · April 15, 2021, 09:28:23 AM

I think I better do that too - been running stereo lately

MarshallJMP · April 15, 2021, 01:11:33 PM

You will only have this problem when running in bridge mode.

Harley Hexxe · April 15, 2021, 01:15:58 PM

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)

Lyates1987 · April 23, 2021, 08:54:14 AM

Is $200 shipped a fair offer on the MT-200 nowadays?

Harley Hexxe · April 23, 2021, 12:51:03 PM

Quote from: Lyates1987 on April 23, 2021, 08:54:14 AM
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)

Dante · April 23, 2021, 01:17:09 PM

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.

Lyates1987 · April 26, 2021, 08:28:35 AM

Quote from: Dante on April 23, 2021, 01:17:09 PM
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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MT-200 FAQs