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-   -   Modulus-186 for a highly sensitive speaker (https://www.diyaudio.com/forums/chip-amps/331874-modulus-186-highly-sensitive-speaker.html)

jazzlampe 31st December 2018 12:49 PM

Modulus-186 for a highly sensitive speaker
 
Hi,
this is my first post. I kept reading for a while but now there are questions coming up and threads concerning the modulus-186 seem to be rather rare.
I'm planning to build an amplifier that will drive the high frequency part of my active speakers. It's a compression driver delivering 110dB from 1W/1m (modified RCF CX15N35). With such a high sensitivity speaker supposed to play at living-room-level I need a dead silent amplifier. Tom's announcement for the modulus-186 gave me something to chew on for my holidays. 45 watts is more power than I would ever need. Meagre 15mW result in 85dB at my listening position. But these 15mW should be of certain quality concerning noise, hum and distortion.
I'm plannung to build a stereo system of 2 modulus-168. Input is coming from a MiniDSP 8x10 (differential at 4V). The minimum gain of 20dB within the modulus-168 should suffice, am I right on this? Power is to be delivered by a conventional toroidal transformer with a Power-86.

Now to my questions:
  • Is this a useful combination? (Technically. Not in term of good sound, that is a matter of experiment. In case it does not match, the modulus will make good friends with a conventional passive speaker upstairs.)
  • I appreciate some amount of smartness. In my case, how useful is a softstart like the neurochrome ISS?
  • How useful do you estimate a protection circuit like the Guardian-86?

Im not all new to building, but power amplifers are new to me. So any advice and suggestions are appreciated.

Cheers,
Adrian

sq225917 31st December 2018 01:57 PM

Sounds like you need a pre-amp not power amps.

jazzlampe 31st December 2018 04:38 PM

Sure, my demands seem closer to attenuation than amplification:D.
In fact my setup is all digital, the MiniDSP serving as crossover, RoomEQ, DAC AND Preamplifier. Usually attenuation is around 25dB, depending on recordings. Amplification - even on an extremly low scale - is needed.


Thank you, and now we should be back in New Year's Eve party business.

kokoriantz 1st January 2019 05:56 AM

Use Tpa6120a2 x4 parallel .

benb 1st January 2019 06:49 AM

How much power is your amp for your woofer, and what's your woofer sensitivity? You might calculate the max dBSPL of your woofer, then add an L pad/resistor divider on your tweeter amp to make the tweeter then same max volume, something like 4 ohms and 1/2 ohm, presuming the tweeter works well driven from a 1/2 ohm source impedance. This would reduce the amplifier's residual noise as well as limit the tweeter's output and help protect your hearing (!).

jazzlampe 1st January 2019 10:40 AM

Happy new year everybody!

Quote:

Originally Posted by kokoriantz (https://www.diyaudio.com/forums/chip-amps/331874-modulus-186-highly-sensitive-speaker-post5649650.html#post5649650)
Use Tpa6120a2 x4 parallel .

That parallel-OpAmp-thing gave me a decent read, thank you! After all it's an interesting approach but well beyond me, sorry.

Regards,
Adrian

maty tinman 1st January 2019 11:02 AM

Aksa Lender SE Class A Preamp
 
Quote:

Meagre 15mW result in 85dB at my listening position. But these 15mW should be of certain quality concerning noise, hum and distortion.
I think you should think/read:

AKSA's Lender Preamp with 40Vpp Output

jazzlampe 1st January 2019 11:09 AM

Quote:

Originally Posted by benb (https://www.diyaudio.com/forums/chip-amps/331874-modulus-186-highly-sensitive-speaker-post5649662.html#post5649662)
How much power is your amp for your woofer, and what's your woofer sensitivity? You might calculate the max dBSPL of your woofer, then add an L pad/resistor divider on your tweeter amp....

Sensitivity-matching is all done in the digital domain of the miniDSP.
Maybe I should provide some more info on the whole thing: My loudspeakers are active Martion Bullfrogs with a 15" Woofer (94dB/W/m) and the aforementioned coaxial horn (110dB/W/m).
Right now the system is driven by the stock 4-channel amplifier from Martion. LF is 2x 350W class AB, HF is 2x 10W class A. Latter is a wonderful sounding device that just makes a little bit too much noise to my taste. Since it's a commercial product with all its parts in one enclosure one can only speculate on concurrent causes.

So that's where my idea of a separate low noise amplifier comes from.

kokoriantz 1st January 2019 12:33 PM

tpa6120 modules
 
1 Attachment(s)
You need 4 of this . See on Aliexpresshttps://www.diyaudio.com/forums/data...AAAElFTkSuQmCC for others.

kokoriantz 1st January 2019 12:50 PM

or this
 
1 Attachment(s)
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