Review and Measurements and miniDSP 2x4 HD DSP and DAC

[Westsounds]

Hiss can be annoying in a modern hifi. We've become so used to the low noise floor digital is capable of.

 

[vicenzo_del_paris]

I’ve been using a DDRC-24 for many years alongside a high-gain amplifier. It does produce a faint hiss from the tweeters, which becomes inaudible at a distance of about 30 cm. from the tweeter. In the thread, I came across someone who reduced the noise by replacing the power brick. I’m considering trying that out, purely as an experiment.

Don't even try. I did try it naively few years ago when I had a ddrc24 with hiss in my tweeters.
Didn't make any difference (as expected).
Replaced it with a flex and hiss went away.

 

[Old_School_Brad]

Don't even try. I did try it naively few ago when I had a ddrc24 with hiss in my tweeters.
Didn't make any difference (as expected).
Replaced it with a flex and hiss went away.

I probably would. But only if I have one in my workshop.
The hiss is inaudible 20-30 cm. away from the speakers anyway. It's not detracting anything from the dynamic range...

 

[vicenzo_del_paris]

I probably would. But only if I have one in my workshop.
The hiss is inaudible 20-30 cm. away from the speakers anyway. It's not detracting anything from the dynamic range...

In my case, hiss was audible up to 1 meter (94 db sensitive speakers at that time, replaced since).
After few back and forth with minidsp support back in 2022, I was left with no solution. It was not even an issue with gain structure.
While not be being an issue at MLP it was annoying me.
I naively tried (without having much expectation) a better linear power supply. Did not make a single difference (of course).
Then I decided to get a Flex instead (to be used as a proper preamp with display and volume control).
While there were no audible difference in audio quality (as expected), the hiss completed disappeared, even with ear against the tweeter in same setup and environment.

And since, I replaced the Flex for a Flex HT that allowed me to get rid of my AVR for my mixed 2.2 (music) and 3.2 (HC) setup using the Flex HT as a multichannel preamp/xo/drc pro and existing power amps.

 

[Old_School_Brad]

In my case, hiss was audible up to 1 meter (94 db sensitive speakers at that time, replaced since).
After few back and forth with minidsp support back in 2022, I was left with no solution. It was not even an issue with gain structure.
While not be being an issue at MLP it was annoying me.
I naively tried (without having much expectation) a better linear power supply. Did not make a single difference (of course).
Then I decided to get a Flex instead (to be used as a proper preamp with display and volume control).
While there were no audible difference in audio quality (as expected), the hiss completed disappeared, even with ear against the tweeter in same setup and environment.

And since, I replaced the Flex for a Flex HT that allowed me to get rid of my AVR for my mixed 2.2 (music) and 3.2 (HC) setup using the Flex HT as a multichannel preamp/xo/drc pro and existing power amps.

That's great, thanks so much for sharing! If I had speakers as sensitive as yours, I definitely wouldn’t have held onto the DDRC-24 for as long as I have.

I use a Wiim Pro Plus ahead of the DDRC-24, and honestly, I have no complaints about my setup.

 

[VanTechMag]

I have a main question to every Equalizer expert here...

Background... I am now using a truly excellent Yamaha GE-40 equalizer (which offer 10 stereo band with red diods +-15db 110dbAihf 0.005% 10-100khz made 1985-86) to adjust bad recordings before I save them on one of my Sony MDS-JB730QS

(my complete stereo scourse setup is - Sony CDP-XB720 cd player / Pioneer BDP-LX55 bluray / Tuner via Zone 2 from my Yamaha Receiver / Sony 75 inch TV / Denon DP-37F turntable / Acer notebook via SoundBlaster THX pro > Denon PRA-1200 preamp > Yamaha GE-40 "recording adjust" equalizer > Sansui SE-77 "headphones" equalizer > Yamaha RX-A1030 av receiver > its parametic equalizer, that I use as main playing eq > plus Yamaha's 7 channel setting > three Cerwin-Vega AT100 modified for TMT configuration & two cute Klipsch as back speakers)

But the sublime GE-40 is almost 30 years old now and may naturally die tomorrow, so I wonder about the best alternatives under 400 euro used or new...
And yes I especially love that following also have Stereo sliders (just as my old Yamaha) so I don't have to adjust every band twice for right and left!

Here did I just find, some new possibilities •• WiiM pro plus? •• WiiM ultra? •• miniDSP 2x4 HD?

*And since my SoundBlaster THX pro don't always work, would be an extra advantage if I can use these as a fine USB DAC for PC to stereo & stereo to PC course...
And maybe even to convert digital in signals to analog RCA out??

•• The extremely rare and at least 15 years old Behringer DEQ1024 (31stereo +-12db bands from 20hz to 20khz, it has also mono > stereo > wide adjustment, 2st 12 led meters, handle 15-35000hz S/N -104db within 22hz22khz 0,004% and international power supply) ??
•• Behringer DEQ2496 UltraCurve pro??
•• A very old Yamaha YDG2030 studio equalizer (parametric slim black 20bit 44.1hz +-12db 30 band 40 memories S/N 106db 0.007% only XLR connections) ??
•• Something that is even better, under 400 euro used???

So what is the best alternative for a new "music adjusting equalizer" that are both very transparent and reliable - as my old Yamaha GE-40?!?

Any advice is naturally warmly welcome!

New member - Björn Blomberg

 

[Old_School_Brad]

I have a main question to every Equalizer expert here...

Background... I am now using a truly excellent Yamaha GE-40 equalizer (which offer 10 stereo band with red diods +-15db 110dbAihf 0.005% 10-100khz made 1985-86) to adjust bad recordings before I save them on one of my Sony MDS-JB730QS

(my complete stereo scourse setup is - Sony CDP-XB720 cd player / Pioneer BDP-LX55 bluray / Tuner via Zone 2 from my Yamaha Receiver / Sony 75 inch TV / Denon DP-37F turntable / Acer notebook via SoundBlaster THX pro > Denon PRA-1200 preamp > Yamaha GE-40 "recording adjust" equalizer > Sansui SE-77 "headphones" equalizer > Yamaha RX-A1030 av receiver > its parametic equalizer, that I use as main playing eq > plus Yamaha's 7 channel setting > three Cerwin-Vega AT100 modified for TMT configuration & two cute Klipsch as back speakers)

View attachment 415324

But the sublime GE-40 is almost 30 years old now and may naturally die tomorrow, so I wonder about the best alternatives under 400 euro used or new...
And yes I especially love that it have Stereo sliders (just as the following alternatives) so I don't have to adjust every band twice for right and left!

- miniDSP 2x4 HD?
- The extremely rare and at least 15 years old Behringer DEQ1024 (31stereo +-12db bands from 20hz to 20khz, it has also mono > stereo > wide adjustment, 2st 12 led meters, handle 15-35000hz S/N -104db within 22hz22khz 0,004% and international power supply) ??
- Behringer DEQ2496 UltraCurve pro??
- A very old Yamaha YDG2030 studio equalizer (parametric slim black 20bit 44.1hz +-12db 30 band 40 memories S/N 106db 0.007% only XLR connections) ??
- Something that is even better, under 400 euro used???

Any advice is naturally warmly welcome!

New member - Björn Blomberg

Oh, so that’s what they refer to as a "revealing system" over on Audiokarma?

Spoiler: NSFW

 

[Willem]

This thread is now so long that I cannot easily find the answer for my question, if there was one. I use the 2x4HD to apply MSO filters to the analogue rca subwoofer feed from my ADI-2 and then the analogue 2x4HD output to my subs. I know I can set the input sensitivity of the 2x4HD to 2V or 4V. Given that the ADI-2 can output pretty high levels, would the mediocre performance of the 2x4HD improve a bit with the higher 4V input sensitivity? Amir's test does not say what input sensitivity he used.

 

[johny_2000]

Given that the ADI-2 can output pretty high levels, would the mediocre performance of the 2x4HD improve a bit with the higher 4V input sensitivity?

It will probably be a few dB better. A higher signal amplitude compared to a constant noise level will result in a better Signal-to-Noise Ratio. Other parameters like THD, IMD etc. need to be measured in both cases using an audio analyzer to get the answer. This is not so critical for subwoofer frequencies (from 20 to 140 Hz), and as previously tested, the human ear is unlikely to detect any harmonic distortion in this range unless it exceeds 10%.

What ADI-2 DAC are you using? Does it have OPTICAL OUT?
You can start your own thread in the main DAC section of the forum and discuss your actual setup, settings.
I think there is a better way to drive a subwoofer than re-digitizing the DAC output with a mediocre 2x4HD analog input.

 

[Willem]

I know human hearing is less sensitive to such imperfections at subwoofer frequencies, and I know that theoretically the 4 V input level should be a few dB better, but I was curious about actual measurements.
I am using the RME ADI-2 DAC FS, i.e. the basic model. The system has various digital sources (none analogue) into the ADI-2 that serves as a preamp as well, using the volume control and all the other great feautures. I use the xlr output into my power amplifier and the rca output into the 2x4HD, using MSO filters, into three subwoofers. So I only use the 2x4HD for the subwoofer output. The ADI-2 does not have a digital output, so I would not know how I could connect the subs differently and still use the various features of the ADI-2.

 

[johny_2000]

I am using the RME ADI-2 DAC FS...
The ADI-2 does not have a digital output, so I would not know how I could connect the subs differently and still use the various features of the ADI-2.

Got it. My ADI-2/4 Pro SE has an optical (digital) output which I sometimes use to feed the signal to subsequent DACs with ADI-2 volume/EQ/loudness pre-processing.
Your setup with ADI-2 DAC FS (RCA) -> 2x4HD (Analog In, MSO plugin) -> 3 x RCA to SUBs will work fine too.
You can open 2x4HD and switch the Analog In jumpers to 4V mode, then increase the RCA amplitude of the ADI-2 DAC FS output signal to +13dBu.