MTM with 5" or 6" bass-mids

andyjevans · 22nd September 2010, 02:59 PM

I was thinking of a 7" 2-way build, but I think I should look at MTM before committing.

I already have a pair of Monacor SPH 130AL which are aluminium cone, SD80 fs48hz, Qts .32, vas 11L. They are 8 ohms so could be paralleled to give 4 ohms with a 4 ohm tweeter. Sensitivity is 88db.

How good would such a speaker sound? If this is a good idea please mention some other 5" or 6" bass-mids that sound good in existing designs I might consider. I'd be hoping to drive the speakers with a 300b SET so 8 to 10 watts.

andy

Zeverin · 22nd September 2010, 03:50 PM

Using 6" drivers in a MTM configurations will benefit from the higher sensitivity. Do you any ideia of which tweeter you will use? To take full advantage of the MTM configuration the tweeter needs to have 91 dB of efficiency, and must be able to cross low. Is the amp able to deal with a low impedance? I think it is, but is better to check first.

andyjevans · 22nd September 2010, 04:43 PM

I was thinking of the SB-Acoustics SB29RDC. This has a sensitivity quoted as 93db and can be crossed over at 1.5K as I read it. I'm guessing the lower you can cross over with MTM the less problems you have with integrating two mid-bass speakers.

A tube amp has an output transformer, so I would make sure this was wired for 4 ohms out.

Thanks for any more suggestions!

andy

andyjevans · 22nd September 2010, 04:46 PM

I found this unit which is somewhat similar to the Monacor in size and cone material.

http://www.zaphaudio.com/ZA14W08/ZA14W08-datasheet.pdf

Here it is used in designs including MTM

Zaph|Audio - ZA5 Speaker Designs with ZA14W08 woofer and Vifa DQ25SC16-04 tweeter

andy

StigErik · 22nd September 2010, 05:35 PM

Down worry about the tweeter sensitivity. If you do a proper Baffle Step Compensation if your x-over, you wont get more than 87 dB sensitivity from the two midwoofers. With that sensitivity figure, an 8W amp dont seem like a good option to me. If you want good efficiency use some light-weight paper-cone drivers rather than heavy aluminium.

andyjevans · 22nd September 2010, 06:12 PM

I have to say that I have no experience of designing crossovers. I have the components because I build my own amps, I just don't have any speaker software to calculate stuff with, plus I use a Mac so any software has to work on that. Consequently I know nothing about baffle step compensation, which clearly I should, especially with MTM arrangements.

Actually Zaph shows two designs for the ZA5

Zaph|Audio - ZA5 Speaker Designs with ZA14W08 woofer and Vifa DQ25SC16-04 tweeter

One is a MTM and the other is a 2.5 way with tweeter at the top. Which of these designs is better?

andy

22nd September 2010, 02:59 PM	#1
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	MTM with 5" or 6" bass-mids I was thinking of a 7" 2-way build, but I think I should look at MTM before committing. I already have a pair of Monacor SPH 130AL which are aluminium cone, SD80 fs48hz, Qts .32, vas 11L. They are 8 ohms so could be paralleled to give 4 ohms with a 4 ohm tweeter. Sensitivity is 88db. How good would such a speaker sound? If this is a good idea please mention some other 5" or 6" bass-mids that sound good in existing designs I might consider. I'd be hoping to drive the speakers with a 300b SET so 8 to 10 watts. andy

22nd September 2010, 05:35 PM	#5
StigErik diyAudio Member Join Date: Feb 2008	Down worry about the tweeter sensitivity. If you do a proper Baffle Step Compensation if your x-over, you wont get more than 87 dB sensitivity from the two midwoofers. With that sensitivity figure, an 8W amp dont seem like a good option to me. If you want good efficiency use some light-weight paper-cone drivers rather than heavy aluminium. __________________ dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles

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22nd September 2010, 03:50 PM	#2
Zeverin diyAudio Member Join Date: Oct 2007	Using 6" drivers in a MTM configurations will benefit from the higher sensitivity. Do you any ideia of which tweeter you will use? To take full advantage of the MTM configuration the tweeter needs to have 91 dB of efficiency, and must be able to cross low. Is the amp able to deal with a low impedance? I think it is, but is better to check first.

22nd September 2010, 04:43 PM	#3
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	I was thinking of the SB-Acoustics SB29RDC. This has a sensitivity quoted as 93db and can be crossed over at 1.5K as I read it. I'm guessing the lower you can cross over with MTM the less problems you have with integrating two mid-bass speakers. A tube amp has an output transformer, so I would make sure this was wired for 4 ohms out. Thanks for any more suggestions! andy

22nd September 2010, 04:46 PM	#4
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	I found this unit which is somewhat similar to the Monacor in size and cone material. http://www.zaphaudio.com/ZA14W08/ZA14W08-datasheet.pdf Here it is used in designs including MTM Zaph\|Audio - ZA5 Speaker Designs with ZA14W08 woofer and Vifa DQ25SC16-04 tweeter andy

22nd September 2010, 06:12 PM	#6
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	I have to say that I have no experience of designing crossovers. I have the components because I build my own amps, I just don't have any speaker software to calculate stuff with, plus I use a Mac so any software has to work on that. Consequently I know nothing about baffle step compensation, which clearly I should, especially with MTM arrangements. Actually Zaph shows two designs for the ZA5 Zaph\|Audio - ZA5 Speaker Designs with ZA14W08 woofer and Vifa DQ25SC16-04 tweeter One is a MTM and the other is a 2.5 way with tweeter at the top. Which of these designs is better? andy

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