TOPIC:

I use the digital input too but that doesn't change anything. Same noise as while using analog.

I understand you pain... Iam really pissed of too. 500€ for one plate amp and than it makes noices


But with the resistor hack it works fine for me... But unfortunately the support doesn't take the problem seriously. I corresponded with them several times last year and gave up in the end because my colleagues didn't understand or didn't want to understand. In the meantime, I suspect that the colleagues at MiniDSP cannot reproduce the error and that it may be due to the power grid in the respective country.

But if you sell an amp for 500€, the electronics should be able to buffer such fluctuations, but well....

Thanks for your answer,

then I'll give it a try. Just to be shure. I need 4 resistors and connect them parallel to the four inputs of my amps as shown in the
picture?



Thanks again
scharno

correct you first can test it by just inserting the resistors in the connector befor soldering it in. And whats important, you need to shield every audio-cabel-pair, if they arent shielded already. I just used copper-tape, but its irremovably bond, alternatively you could use aluminium foil with Testa adhesive tape.

Yippieh!!! It works!

So at last I'm happy. I shielded the cables and did the resistor hack. Now the noise is still there but to hear it I nearly have to stick my head into the speakers.
For all frustrated friends here is what I did in detail.

First I very, very and I mean very carefully pulled the pins of each signal cable out of the little white plugs. Then I widened a piece of desoldering braid which in fact is nothing but a little copper hose, pulled it over the cables and fixed it with a small piece of self adhesive tape.





This done the noise was still hearable but a little bit quieter. Then I tried 100 Ohm resistors on each channel but that didn't change anything. Next I used 150 Ohm and believe it or not the hum and the sweeping noise was nearly gone. Maybe the noise problem depends on the local current but for Germany these two workarounds do the job. Disconnecting any grounds did not work nor did the separation of power and signal cables show any changes.

Oh, another very important information!!!
If there is any television in your home pull out the antenna cable and check if this reduces the hum level. If so get yourself a sheath flow filter (hope Google translated correctly).

OK, I was really fed up with my problems with my Power-ICE plate amplifier module..
All four I own are subject to noise issues with different symptoms. All four generate the 50/100 Hz (Europe) noise, which is however very very low and not hearable except when listening close to the driver itself. I would say normal for an amplifier. All four generate high frequency random noise hearable through the tweeter. Again very low and not really a problem (94dB/W/m drivers).
Now the problems : two of them generate sweep sine noise in the 100 Hz 1kHz band. I would say some kind of frequency hooking, sweeping with a 10 to 20 seconds period. This one is hearable during normal listening, annoying and disturbing. And the worst, one module was reluctant to generate signal with correct level, sometime it worked, sometime level was down by few dBs, sometime more noisy with level down to 10 or 20 dB...Tapping on the plate sometime cure the problem...
That said, I removed the 8 wires signal flat cable and decided to solder wires straight to the PCB connectors. I used RG179 coax cable for the audio signal, and it works !
No more sweep sin noise, no more relaibility issues, everything is now perfect.
MiniDSP Power-ICE is really a great product, it would really deserve better manufacturing quality.

My experience with the noise: I can hear a low frequency noise (100, 200Hz) produced by the midrange speaker.
A swinging sweep sine (only high frequencies) and high frequency noise by the tweeter , but no noise in the bass

I am using four PWR ICE (two ICE 125 and two ICE 250) in a daisy chain (AES-EBU input)
ICE250 in BTL Mode for Bass-system and ICE125 in SE mode for Mid range and tweeter

All Measurements of the noise with REW: Microphone UMIK 1; Realtime analyzer RTA 1/48 octave
All measurements with Microphone with a distance ca. 1 cm at the membrane.

PWR-ICE conditions: No inputs; outputs are all muted; the only cable to the PWR-ICE is for power supply (220 V)

1:REW measurement: background noise of the room (all PWR ICE power off): there is a small peak at 50 Hz at 40 dB (SPL); it may be from the computer system (in battery mode). Still the same if the Mikrofone is under big pillows.

All other measurements with power on PWR ICE (no input signal !!):
Loudspeaker system : Bass two Tang Bang W6-1936S in a closed box; Midrange: bohlender & graebner NEO 10 planar magnetic transducer in a wooden tractrix 200 Hz horn; tweeter ESS AMT 1
REW midrange in SE mode ; noise at 100 Hz, 200 Hz 300Hz etc…, you can hear the noise up to 1m distance
3.REW Tweeter in SE mode ;noise at 300 Hz 400 Hz… 2 kHz, you can hear the noise up to 1m distance clearly, and some sweep sine
4:REW Bass system in BTL mode ; no noise
The only difference between this measurement is the SE mode for Mid and tweeter and BTL mode for bass

Next measurements for testing difference between SE and BTL mode :
5.REW: Now mid range but in BLT mode, no noise, „no sweep sine“
6.REW: Now tweeter in BTL mode ; no noise no „sweep sine“
7.REW: Bass in SE mode; noise at 50Hz ; 100 Hz; 200 Hz ….; noise clearly to hear

The reason for all of these seems to be the SE / BTL mode. (SE mode use ground but BTL mode do not use ground). There bay be a potential difference between ground of the DSP module and the ICE-Power module

Test: disconnect the +- 24 volt power supply from ice-power to mini DSP module: no noise at all. Same if you disconnect the signal connection between mini-dsp and ice power model.
Conclusion: The reason for the noise is not the ice power module. It seems to be a potential problem between ice power module and mini-dsp module in SE mode (using ground). In BTL mode both hot outputs are used.
The simplest solution is: use only BTL mode
Any ideas for other solutions for SE mode ? (except using a capacitor = passiv high pass filter )

sorry for the missing measurements

 

Good detective work Kunzmann. Lucky for me I will be using the amps in BTL mode.

Will you try the cable modifications shown earlier in the thread to reduce the noise on the SE mode units?

Hi,

I too have noise problems with PWR-ICE 125 (230V).
I have two.
One amp is nearly silent, but the other amp gives hum and noise.
And these amps are in BTL mode! Driving each a 10" subwoofer! (88 db sens.)
The noise did go away for a while when fiddling with the RCA connector, but that was more or less by coincidence..
I have 2 sub RCA preouts on my receiver, and swapping signal cables didn't make any difference.

Edit:
I cut the cable tie and separated the DSP circuit power wires from the signal input wires, as suggested.
That seemed to calm things down a bit, but the noisy amp still produces a clear 50 hz in the woofer.
It didn't help.

Edit:
The noise amplitude is relative to master volume knob position.
Noise improves 95% if I disconnect the RCA cable.
(Then it sounds similar to the other amp *with* the RCA connected).
Noise is kind of bizarrre, it has a computer like bleep at times.


 

Ha ha!
I can't believe it worked..
I simply tried a lowpass filter in the problematic PWR-ICE module...noise gone!
This is a "fix" for me as I use them for subwoofers.
I haven't tweaked the sound yet, as one of the modules has an abused ethernet socket that I'm going to replace.