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AUDIOPHONICS MPA-S250NC Amp Review
- Thread starter amirm
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tsfreo
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Just a further experience to reinforce what you suggested about contacting Audiophonics.
I emailed them at what would have been about 730am Paris time (I am in perth, Western Australia) and they came back 90 minutes later (about 9.05am Paris time) with a specific response to my query - saying that my proposed Rotel pre would be no problem. Terrific customer service.
I recently bought this amplifer to drive a B&C DE250 (108 dB sensitivity) compression driver in a 2-way active setup. Unfortunately there is a hiss that is very audible from the listening position. The hiss is audible even when the amp is not connected to my benchmark dac so I assume the amp is the culprit.
I am quite new to this so I would really value some help. Is this normal for this amp? Is there a way to mitigate the issue?
I made some measurements with a UMIK-1 measurement microphone and have attached a screenshot from REW. The brown line is with the amp turned off. The green line is with the amp turned on.
Audiophonics were unhelpful to say the least. Basically told me that I was imagining things and that there was no hiss.
I am quite new to this so I would really value some help. Is this normal for this amp? Is there a way to mitigate the issue?
I made some measurements with a UMIK-1 measurement microphone and have attached a screenshot from REW. The brown line is with the amp turned off. The green line is with the amp turned on.
Audiophonics were unhelpful to say the least. Basically told me that I was imagining things and that there was no hiss.
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Certainly not ''normal'', mine is dead silent though i don't run through-the-roof sensitive speakers, i guess you obviously should test it on another system and send it back if it keeps doing that. Are you using RCA or XLR btw?
tsfreo
Member
My LPA-S500NC, which is a similar hypex based amp from Audiophonics is also dead silent - though I run Lintons which are 90dB sensitivity.
I use XLR connects.
yllanos
Active Member
I have the same amp. Same experience, also using balanced connection
When even a UMIK-1 can measure the hiss it's for sure to much!
And a compression driver is COMPLETELY different in noise floor demand as a 90dB speaker ... 2 worlds between.
I use 3" midranges and Hypex plate amps and can hear a little hiss in 1,5m distance - so it can happen you hear significant hiss in your setup.
To your setup - active speaker, direct connection of DE250 to amp? 8R or 16R compression driver? What's the rest of the setup?
You could do a mix of active and passive crossover - for some behaviours that's actually the only way (e.g. dampening resonances with passive components). When linearising the fr with a capacitor and lowering the level by 6-10dB you would defeat a lot of noise. The fine tuning and crossover is done active.
One more test - you can use to shorten the input of the amp, that's the lowest noise setup possible. Just build a XLR connector with pin 2 & 3 shortened or connected with a 10-20R resistor. An open input can pick up hiss and is a high impedance termination which has some noise by itself.
Sokel
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I'm I the only one who doesn't see any hiss in this graph?
(I suppose this is with a calibrated mic.Hiss area is as low as it gets there.Maybe you mean some other kind of noise? )
Seems like.
Umik has A LOT of noise. When it measures 2-3dB higher noise as it's own noise level it's for sure easily audible.
Sokel
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I didn't know that,I use normal mic with mic pre,etc.Seems like.
Umik has A LOT of noise. When it measures 2-3dB higher noise as it's own noise level it's for sure easily audible.
But,is it SPL calibrated?Cause the hiss area shown (lows are just environmental and can vary a lot) is at 0dbSPL,that's why I say it's strange.
@tgestsson at what distance is that measurement?
Thanks for all the helpul comments.
@Sokel
The measurements are made at the listening position at 3.5m. I live in the centre of town and there is quite a lot of ambient noise in my house.
@IamJF to answer your questions:
This is what my setup looks like:
MacBook --> MiniDSP 4x10hd -->
digital output --> benchmark DAC --> Audiophonics MPA-S250nc --> Tweeter (B&C DE250 4ohm)
Analog output --> PrimaLuna Dialogue One --> Woofer (Acoustic Elegance TD-12M 4ohm)
I will look into using some passive components. I am currently using a 47uF capacitor in series to work as a high pass filter to protect the compression driver but this has a much lower crossover frequency than the active crossover which is at around 1000hz. I've seen some people use resistors to attenuate the signal to compression drivers. I expect that would drive down the noise floor. Is that something that I might look into?
@Sokel
The measurements are made at the listening position at 3.5m. I live in the centre of town and there is quite a lot of ambient noise in my house.
@IamJF to answer your questions:
This is what my setup looks like:
MacBook --> MiniDSP 4x10hd -->
digital output --> benchmark DAC --> Audiophonics MPA-S250nc --> Tweeter (B&C DE250 4ohm)
Analog output --> PrimaLuna Dialogue One --> Woofer (Acoustic Elegance TD-12M 4ohm)
I will look into using some passive components. I am currently using a 47uF capacitor in series to work as a high pass filter to protect the compression driver but this has a much lower crossover frequency than the active crossover which is at around 1000hz. I've seen some people use resistors to attenuate the signal to compression drivers. I expect that would drive down the noise floor. Is that something that I might look into?
Do you have a measurement of the tweeter?
You could start with a way smaller capacitor and do some of the needed correction with the capacitor. And of course a simple resistive divider network will lower the level and also the noise.
You could start with a way smaller capacitor and do some of the needed correction with the capacitor. And of course a simple resistive divider network will lower the level and also the noise.
Looking to get an amp and thinking about this one or the "internetofmusic" one.
I dont really understand how the trigger works though. I have linn majic amps in my living room and those detect input and turn on.
On these, there is a seperate cable needen? With what do i connect it? Planning to use a Singxer-SA 1 as pre-amp
I dont really understand how the trigger works though. I have linn majic amps in my living room and those detect input and turn on.
On these, there is a seperate cable needen? With what do i connect it? Planning to use a Singxer-SA 1 as pre-amp
soerenssen
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Can I drive the following HT setup with the 4 channel version of this amp or would you recommended something else?
- center (2 channels of the amp, bridged): KEF R6 Meta (4ohms, min. 3.2 ohms, 275W recommended, 88dB sensitivity)
- 2x surrounds (one speaker connected per channel): currently Q350, soon to be replaced with KEF R3 (according to the original specs 8ohms but like the R6 it goes down to 3.2 ohms, 200W recommended, 87dB sensitivity)
- center (2 channels of the amp, bridged): KEF R6 Meta (4ohms, min. 3.2 ohms, 275W recommended, 88dB sensitivity)
- 2x surrounds (one speaker connected per channel): currently Q350, soon to be replaced with KEF R3 (according to the original specs 8ohms but like the R6 it goes down to 3.2 ohms, 200W recommended, 87dB sensitivity)
soerenssen
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They don't have a 3-channel version and for 2xstereo I don't have enough trigger outs. Also, the center is larger than the surrounds, will be used more and I was thinking "more headroom". Better than not using the 4th channel I guess.
I would not stress the power amp with a 2R load in bridged just to get headroom which would destroy the speaker when used. So I would just use the channels "normal" and leave one channel unused. More power supply headroom for the center.
But your way is of course also possible to do.
But your way is of course also possible to do.
soerenssen
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Why would it destroy the center?
For example, when I contacted KEF and they recommended the Hegel H590. Way more powerful than what is reasonable for these speakers.
If I'm doing this right, according to the Crown calculator one of these units will give me L/R 80db SPL at 3m with 16.5 DB headroom. Or 84db at 12.5db headroom.
I don't listen much over 80 dB so this looks like the perfect fit for both music and home theater.
I don't listen much over 80 dB so this looks like the perfect fit for both music and home theater.
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4R bridged is not spezified and 2R use activeted the protection circuit. So it will have at least 500W bridged, maybe more shortterm. The KEF is spezified 15-250W.
It seems a stretch for the amp and the speaker.
@Acerun SPL levels in rooms don't fall off at 6dB per double distance! (I bet the Crown app is calculating with that)
You are sitting in the pure reverberant field in a normal room in 3m - you will get higher SPL.
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