2x 125ASX2 BTL or 2x 250ASX2 BTL?

[EB1000]

Hello

My first post here. I'm looking to upgrade my front channels amp for a better music listening. I have a pair of Martin Logan Motion 20 loudspeakers:

MartinLogan | Motion 20

Connected to a Denon AVR-X4400H AV receiver. I plan on building a dual-mono power amp using ICepower modules in BTL mode. I really can't decide whether should I go with the 250 or 125 modules? It seems that the 125 have lower THD, but half the power ratings. The recommended amp for the Motion 20 is 20 to 200W. I also have two SVS SB2000 subs, so the Motion 20s are cut at 60Hz by the receiver LPF.

Which would suit my needs best and be a better match for my speakers?

Also, which single-end (RCA) to balanced (BTL) converter board should I get for best performance? can hold t

Thanks

 

[chermann]

Hi EB1000

nice speakers! i check the internet but i do not found a impedance plot for your speakers.
facts:
4R impedance - normally some frequency will be below that ! --> 2.5 3R
90DB Efficiency is very good and you will not push hard the get your music volume up to party volume.

125ASX2 -BTL
4R 1% you get 450 Watt so this module should be good- but the min. impedance is 3R (page 7)

250ASX2 -BTL
8R 1% you get 500 Watt - the min. impedance is 4R (page 7)

mybe i am wrong...but....you should use 2 modules 125ASX2 -BTL


chris

 

[EB1000]

Hi EB1000

nice speakers! i check the internet but i do not found a impedance plot for your speakers.
facts:
4R impedance - normally some frequency will be below that ! --> 2.5 3R
90DB Efficiency is very good and you will not push hard the get your music volume up to party volume.

125ASX2 -BTL
4R 1% you get 450 Watt so this module should be good- but the min. impedance is 3R (page 7)

250ASX2 -BTL
8R 1% you get 500 Watt - the min. impedance is 4R (page 7)

mybe i am wrong...but....you should use 2 modules 125ASX2 -BTL


chris

Thanks. I've contacted Martin Logan support and asked them for impedance graphs or at least the minimum.

I'm guessing that the worst that can happen is for the amp to go into protection mode. At the moment my Denon X4400H has no problems driving the motion 20 at very high levels.

The Matin Logan motion 60 can reach 2.25 ohms at 300Hz... Not sure about the motion 20..

 

[chermann]

Thanks. I've contacted Martin Logan support and asked them for impedance graphs or at least the minimum.

I'm guessing that the worst that can happen is for the amp to go into protection mode. At the moment my Denon X4400H has no problems driving the motion 20 at very high levels.

The Matin Logan motion 60 can reach 2.25 ohms at 300Hz... Not sure about the motion 20..

Hi

i remember some models by Martin logan that have at 5khz or so a very low impedance!! so if you have here traouble with your amp then its really scratchy

 

[Kay Pirinha]

Also, which single-end (RCA) to balanced (BTL) converter board should I get for best performance? can hold t

I don't know both boards. Don't they feature single ended inputs yet? If not, have a look at the TI TPA3255EVM circuitry and see how it's done there, using a NE5332 dual opamp per channel.
Best regards!

 

[gsrchrisu]

Running 125asx2 in btl mode with RTX modules and cases from ghentaudio with a Denon Avr4100w running as a preamp. Speakers are Energy RC-70 with SVS pc-12 plus and it sounds absolutely amazing. Honestly, the 125asx2 in stereo mode with 65 watts was impressive. Whats the price difference between the 125asx2 and the 250axs2, I doubt you will hear any difference in sound quality. The 125asx2 are running 225 watts into 8 ohms, and really that is way more than you need for 60hz and up. 120hz and down is what gobbles power.