Impedance too low for my reciever?

[jaygeorge1979]

Hello,

I have decided to build one of the many MTM projects I have found on the internet, but I am not sure which ones have a high enough impedance to suit my reciever.

The reciever manual says speakers must be 8 ohms or greater.

http://www.circuitcity.com/ssm/Sherw...Detail.do#tabs

The projects I am considering building are:

http://zaphaudio.com/BAMTM.html

http://www.partsexpress.com/pe/showd...number=302-930

http://ascendantaudio.com/Arbiter_MTM.html

I know the parts express project says nominal impedance is 4 ohms so I guess that one is out of the question. How can I find the impedance of the other two projects?

Thanks!

[jaygeorge1979]

come on fellas, somebody's gotta have the answer to my question

[AndrewT]

Hi,
the arbiter shows two bass/mid drivers in series.
Look up the data to find the nominal impedance of one driver.
Double it and that gives the impedance of the complete speaker for the majority of the music signal.


The Zaph shows a graph that peaks at 10ohms and falls to about 3 to 4ohms over most of the bass/mid range.

Since it uses two bass/mid drivers it is likely that the 3 to 4ohms results from using a pair of 8ohm drivers in parallel. Go look up the data for the driver to confirm. The treble seems to be 10 to 12ohms and this is confirmed by the crossover resistor of 6r adding to the nominal impedance of the treble.

It looks like the majority of MTMs will be 4ohm or 4 to 8ohm. So choose carefully.

I think the others are expecting you to put some effort into your research.
Learn to be a Pink Panther (detective).

[Godzilla]

Hello there! I have a Yamaha receiver that has the same ‘speakers over 8 ohms’ written on the back. When I connect 4 ohm speakers the receiver simply shuts off automatically. Must be some protection circuit.

Most MTM’s are 4 ohm loads. I have seen some that are 6 ohm (they use 12 ohm drivers that sum to 6 ohm after they are wired). That said, I recommend building an 8 ohm speaker project. This would eliminate most all of the MTM designs out there.

This is just my opinion. But a simple quality two-way will tax your amp less and provide even better sound than an MTM.

Godzilla

[v-bro]

If you want the hot d'appolito look you could upgrade your amp to sound even better and make it capable of handling as low as 2 ohms!

If you can handle your soldering iron reasonably well you can get a 4x100W (max.) amplifier with incredibly good sound for 49 EUR.
Look at AMP9 from 41hz.com Maybe the power supply of the receiver can even be used (don't know this for sure...) The board is probably small enough to fit in the case...and consumes relatively little power...

Maybe just one crazy idea, but I've done more weird things that worked very well.....

[jaygeorge1979]

That's sad, I really wanted that look with the reciever I had. Oh well, if it wont work, it wont work. I just figured that a nice pair of MTM's would have plenty of sound to be the mains for a small home theater setup.

What am i gonna do now...?

[leadbelly]

Just keep searching for an MTM with a series crossover that's 8 ohm friendly. I can think of a couple of projects like that, but they sound like they are above your budget. Keep looking

[jaygeorge1979]

hah....yeah i am trying to keep budget to around 200 dollars for drivers/crossover components so I can spend around 200 on those prefab PE cabinets...trying to keep total project expenses (and i mean TOTAL) under 500 bucks

[ralph-bway]

I know nothing about this driver except it's cheap & 16 ohms. Probably sounds like an 80 year old grandparent who's been smoking 3 packs a day since WWII.

Apex Jr has some 16 ohm Onkyos for sale cheap

I have two pair of reconed polk 6.5's (they're 16 ohms), I think the MT 6500's (from their old M-10 monitors. I also have the matching tweeters, crossovers, and a pair of 10' passive radiators.

The Polk m-10's had the two 6.5's on a horizontal line above the 10 " PR's. I had the in a cabinet in an MTM configuration, with the PR on the back cabinet wall behind the 6.5's

It was my second DIY project and I was very impressed withfullness and tight bass.

If you're interested I'd be happy to sell everything at a reasonable price to a fellow DIYer. Other options are to check out specials at Madisound and the speaker section on Ebay. Be careful on Ebay a lot of people sell junk described as high end

Best of luck in whichever route you take, hope you have a great time & it sounds great.

[ralph-bway]

Oops, link to the first driver

http://www.partsexpress.com/pe/showd...number=299-050

Bestest again