TOPIC:

At this moment I am using a DDRC-24. I have a feeling the sound quality is lacking behind the rest of the system. For example when there is a signal, I get a faint noise through my subwoofers when they have the internal lowpass filter turned off (B&W DB4s 2x). When the audio stops this noise stops after 2 seconds. Now I need to set a lowpass filter in the subwoofer AND in the MiniDSP.

My subwoofers and preamp, power amp (Rotel) all have balanced inputs and outputs, but the Minidsp cannot make use of that.

I am thinking about buying the MiniDSP Flex with balanced outputs.

I will lose the ability to use Dirac, but I stopped using that already. I cannot get satisfying results with Dirac. It all feels like it is 'overcorrecting'. The manual approach seems to work better for me (using REW).

The Flex is quite expensive, even without Dirac. Does this really give me an upgrade, or would I regret for not going for the SHD?
I think the SHD offers me no further benefits. The Flex has 2 analog in, 4 out balanced. That is all I need.

The SHD can stream but I do not need any of that. I have my own streamers and my preamp is my source and volume control, so I only use the analog input.

Any thoughts on that?

PS. I know the DSP chip is identical between all models, but what about the AD-DA stage in the DDRC24 and the flex, what chips are used there, is there any information or comparison about that available?

Thanks!

PS. If I reconsider using Dirac. Is it possible to transfer the Dirac license I already own for the DDRC24 to the new unit?

My DDRC24 unit is converted to a 2x4HD.

fheibrink wrote:

PS. If I reconsider using Dirac. Is it possible to transfer the Dirac license I already own for the DDRC24 to the new unit?
 

No: support.minidsp.com/support/solutions/ar...e-g-ddrc-24-to-flex-

Thanks,

Any thoughts on my first question?

I am really in doubt to upgrade. I can repurpose the DDR24 elsewhere, but other than that. It's expensive stuff here in The Netherlands.
I'm hoping this would be a substantial upgrade to the DDRC24. I'm not very satisfied with the performance at this moment. About 80% is due to room acoustics and me not having all the knowledge to fix the DSP part of it (still learning, but time has come to enjoy music instead of technical challenges).

We are also planning on buying a large 125x250x5 cm (about 50x100") acoustical panel (with photoprint) behind the listening position. I have calculated (used an online tool ) that this 6,85m wall is creating the huge 31hz dip. The acoustic panel cannot fix this 31hz problem, but it can have a positive effect on it and also the rest of the audio spectrum.

In the meantime I decided to but the Minidsp Flex Balanced.

I started with a clean slate. I have not looked back at the old configuration and started completely over.

I set my subs to XLR input and without any lowpass filtering (LFE input). With the DDRC-24 this was not possible, it would result in hum every time after some sound was played throught the subwoofers and lasted some seconds after the silence returned. It turned me nuts to find that out, as this was working fine at first, I thought there was some EMI interference happening at first.

I recalibrated the setup en time realigned everything, I had a huge excursion on the subs with lower frequencies and it was too loud there. I created and refined a PEQ (almost only attenuation) for the subs and fiddled with the timing until I got things just right. I cannot remember I had to do this for the DDRC24. I feed the subs with sound from left ánd right, with a -3dB attenuation per channel.

There is a lot of possible expectation bias going on I am aware off, but to my ears it sounds way better! I was very reluctant to use the volume control on the DDRC24 because at 0dB it would blow about every speaker. For the Flex I now have a display and tried using the USB and Toslink inputs for audio. This renders my Rotel RC-1590 useless, but I gain the benefit of having no ADC stage needed anymore (I any play from USB (HTPC) and Toslink (TV). The HF hiss from the speakers is now completely gone due to an all digital signal path. I cannot hear a thing until I am with by ears against the tweeter.

With the RC-1590 connected and the MiniDSP on 0dB I have a hiss I can hear from the listening position, so I attenuated it to -3dB and -6dB and 0dB and made that switchable on the DDRC24. Now this is not needed anymore.

I cannot believe it is only the calibration that resulted in the better sound. PS I have boosted the 10KHz (and IIRC the 3KHz) range a bit (Low Q) modest boost. The B&W CM10 s2's have a slight dip there. It sound to me a bit more crisp now. OTOH I try do to as less as possible above 200Hz.

I am still very careful with the volume control, but it works fantastic.

The only downside is that my Rotel RC1590 is now nothing more than a 12v trigger for my subs and power amplifier.

We're planning on a big Acoustic photoprint to cover the back wall. The dip in the low region is calculated to come from that wall. I hope te get some better results there and faster decay.

Interesting I have found the same setting for my subs at -3db attenuation. I love my minidsp balanced flex and its the single best sonic upgrade I have made in 10 years.

I only use it as an active crossover. I may play with Dirac, Rew down the track.

I run 2 x JLAudio F112 subwoofers and only use the phase controls on them. I now cross them over at 95hz and what a difference. I run Unity Audio Boulder MKI studio monitors. The whole sound is improved. I run an Oppo205 as preamp out to Flex. So all audio runs into Oppo USB input. I don't input anything into the Flex other than preamp. Flex is set at 0 volume and control volume from Oppo.

Going balanced did expose some earth hums which has been solved at 1 sub and earthing Flex. The whole background is way quieter now than unbalanced. I always wanted to go balanced as everything I have is balanced except my old analogue crossover. I have tried other sub attenuation settings but always come back to -3db.

Its critical to get the phase right on your subs. Barry Ober "The Soundoctor" has this white paper that helps: www.soundoctor.com/testcd/index.htm. It works, you do need the actual crossover frequency to play back to set this correctly.