miller and kreisel mx-150 thx

[12L40]

I am new to the audio world and have put together a 7.2.4 Atmos system. Someone recently gave me an old M&K MX - 150 thx subwoofer. I plugged it in to test it out and the volume is very low. I used the subwoofer output on my denon AVR-6400 H. The sub does not have an LFE input. It has a "Left/Mono" or Left and Right options. Will this old beast work with my system?

 

[everettT]

I am new to the audio world and have put together a 7.2.4 Atmos system. Someone recently gave me an old M&K MX - 150 thx subwoofer. I plugged it in to test it out and the volume is very low. I used the subwoofer output on my denon AVR-6400 H. The sub does not have an LFE input. It has a "Left/Mono" or Left and Right options. Will this old beast work with my system?

If the unit is in working order, it was a good one. Do you have your speakers set to small?

 

[lovinthehd]

You might also try a rca splitter so you can use both the L/R inputs on the sub, that generally gives you a little more gain. Did you run Audyssey to incorporate the new sub? Where did you set gain on the sub? Where was the sub pre-out level on the avr set?

 

[12L40]

I do have the speakers set to small. I should add that my other, much smaller, subs work fine.

 

[everettT]

Make sure you have the crossover on the sub all the way up. As loving mentioned using both inputs will add to the input voltage, but I suspect you need a new unit. That sub is getting old.

 

[12L40]

You might also try a rca splitter so you can use both the L/R inputs on the sub, that generally gives you a little more gain. Did you run Audyssey to incorporate the new sub? Where did you set gain on the sub? Where was the sub pre-out level on the avr set?

I have not run audyssy, i will do that asap. There is no gain setting on the sub. The pre-out level is at +12.0 dB
I tried to post a picturebut it says the file is too big.

 

[12L40]

Make sure you have the crossover on the sub all the way up. As loving mentioned using both inputs will add to the input voltage, but I suspect you need a new unit. That sub is getting old.

Yes, i saw reviews on it all the way back to 2000.

 

[lovinthehd]

I have not run audyssy, i will do that asap. There is no gain setting on the sub. The pre-out level is at +12.0 dB
I tried to post a picturebut it says the file is too big.

Is this it? https://www.manualslib.com/manual/104760/Mk-Sound-Mx-150thx-V-125thx.html?page=5#manual

How about the controls in the upper left? Where are they set? It does indicate it's to be connected to a THX controller....maybe that's where gain adjustments could be made....try it with Audyssey but doubt it will help with this additional info. Do try the splitter so you can use both L/R inputs, the gain should help (but may not be enough).

 

[12L40]

Too bad, this thing looks like a beast. It has 2 - 12" drivers.

 

[lovinthehd]

Among the original subs altogether, and good ones. Not a dual 12" driver in the usual sense IIRC, tho, think its a push/pull design.

 

[TLS Guy]

Here is the manual for your unit.

It specifically says not to connect to both left and right inputs.

We used to get quite a few posts on this sub years ago. We have not had one for a while. I do remember we had a lot of posts about the amps failing. I strongly suspect yours has failed.

All is not lost. You could purchase another plate amp and install it. You will have to make sure you have an air seal around the unit.

Your other option is to leave that amp in place and install loudspeaker input terminals and purchase and external power amp.

For that unit either of these suggestions would be worth the money and trouble.

 

[lovinthehd]

Here is the manual for your unit.

It specifically says not to connect to both left and right inputs.

We used to get quite a few posts on this sub years ago. We have not had one for a while. I do remember we had a lot of posts about the amps failing. I strongly suspect yours has failed.

All is not lost. You could purchase another plate amp and install it. You will have to make sure you have an air seal around the unit.

Your other option is to leave that amp in place and install loudspeaker input terminals and purchase and external power amp.

For that unit either of these suggestions would be worth the money and trouble.

What would be the reasoning behind not connecting mono sub pre-out to the left and right input vs stereo left and right output into same?

 

[TLS Guy]

What would be the reasoning behind not connecting mono sub pre-out to the left and right input vs stereo left and right output into same?

The manual is vague about it. It just says not to. I suspect the reason is that it is a waste of time and money. All these sub amps have buffer amps. If they did not then if you connected a true stereo input, then the sending unit would be converted to mono. So any sub buffer amp will do the same thing as a Y-connector with a mono signal, so the Y connector would be totally redundant with all subs.

 

[lovinthehd]

The manual is vague about it. It just says not to. I suspect the reason is that it is a waste of time and money. All these sub amps have buffer amps. If they did not then if you connected a true stereo input, then the sending unit would be converted to mono. So any sub buffer amp will do the same thing as a Y-connector with a mono signal, so the Y connector would be totally redundant with all subs.

What about the 6dB gain advantage that some sub amps would provide with both inputs used?

 

[TLS Guy]

What about the 6dB gain advantage that some sub amps would provide with both inputs used?

Well I suppose that would depend on there being gain in each channel ahead of the signal being combined. All this depends on how the buffer amp is set up. Generally a buffer amp is gain neutral but you can configure it with any gain you want.

 

[KenM10759]

I have an M&K V-90 that is even older. I could not get much out of it with either of my 5.1 systems, and probably because it was meant for no lower than about 40hz @ low volume.

Exceptionally good cabinet though, and the good folks here helped me IMMENSELY in upgrading it to "today's standards for a 12" sealed sub."

It's now the best-sounding sub in my house. That 150 THX is a much better unit, and should be capable of working well. Believe it or not, I found Ken Kreisel will actually reply to e-mails!