Considering Multichannel Audio System Options

[Kal Rubinson]

1.  I did not see the terms DSD or SACD in your text, so another option is a device like the miniDSP UDIO-8, Lynx AES16e PCIe sound card or the Arvus HDMI-2A which will let you stack any three DACs of your choice. 

2.  If you are insistent on a DAC or DACs with balanced output, you should note that the P7 has no balanced inputs only outputs!  That is one reason I prefer the Audio Research MP1.  If RCA inputs are OK, consider the Bryston SP3.

3.  

56 minutes ago, Evo-No-Revo said:

What the most important question I have is how much better can the SQ of the exaSound e38 via USB be over the high end MC pre/pros out there for SQ in a 2 channel or 5.1 setup? 

Not much but enough for me.

[Kal Rubinson]

1 hour ago, Evo-No-Revo said:

Parasound P7...no XLR input. 

Well, it has one balanced stereo input but the multichannel inputs are SE.

[Kal Rubinson]

1 hour ago, Evo-No-Revo said:

Does anyone have a recommendation for best SQ between the Lynx and the mini DSP? 

I do not know of anyone who has tried both and, although I would like to, I do not have a suitable slot for the Lynx in either of the servers I have now.  That said, I am doubtful there will be any audible differences.

N.B.:  Both of these multichannel USB-S/PDIF are limited to 24/192 PCM and no DSD.

N.B.:  The MP1 sounds wonderful but you may note the S/N spec is not up to modern standards and it greatly benefits from being connected to low gain power amps.

[Kal Rubinson]

3 minutes ago, Evo-No-Revo said:

But I will ask him his opinion on how he thinks it will work with the Dartzeel.  I will ask Jonathan as well. 

The Dartzeel amps have a stated gain of 26dB which is a bit lower than standard but not very much.  Depending on the speakers, you are likely to hear some hiss from the tweeters.  To entirely eliminate it, a still lower gain may be needed.

 

8 minutes ago, Evo-No-Revo said:

Kal, do you have a preference for an Oppo 205 substitute.  I see all the usual suspects but does something stand out?

Nope.  I kept my 205 and will probably never replace it because I do not foresee any new physical media format arising in the future.

[Kal Rubinson]

9 hours ago, Evo-No-Revo said:

Do these specs give you a clue to the combination? 

Yes.  87dB is reasonably low.

 

9 hours ago, Evo-No-Revo said:

 

"A note about the MP1. Before taking delivery I had the factory lower the noise floor. I had auditioned the MP1 in Salt Lake and as a condition of sale ARC was to customize. They were pretty accommodating. The included service notes from the initial sale reflect this factory change. "    ?

I had mine done at the factory, too, and it made a difference.  However, here's what they had to say:

Quote

Please keep in mind this product is from another era and adjust your expectation accordingly.  It’s design is borrowed from the REF2.  As such, the A weighted Balanced noise output with the gain control at a minimum is 95 dB below a 2V RMS output (35uV).   Our current electronics are much quieter.

With an ordinary amp (meaning gain around 29dB), there is audible hiss if my ear is about 8" from the tweeter.  I find that disturbing when working in the region of the speakers even though it is inaudible at the listening position.  With lowered gain, I need to have my ear less than 2" away to hear anything and that takes special effort.  It is not a biggie but a head's up.

[Kal Rubinson]

1 hour ago, Evo-No-Revo said:

The buyer I am buying the AR MP-1 from needed more inputs and replaced the MP-1 with the EMM Labs Switchman 3.  One is actually for sale on Superphonica.  I  know where a different Swithman 3 is and I could try it out on demo but I think I can deal with a tiny bit of background  noise and get to look at the front panel of the MP-1.  I love the giant display of the volume.  Switchman 3 is nowhere near as appealing visually.

I almost bought a Switchman 3 several times but the wired remote control is, imho, as good as none.

[Kal Rubinson]

16 minutes ago, Evo-No-Revo said:

Thanks for your input Kalman!

You are welcome.  I hope you find what you are searching for.

[Kal Rubinson]

Let me pop in and say that, if you are doing this "for well recorded MCH classical music," you want the front three speakers to be identical if possible.  They should sound alike and need/not need bass management alike.  The surrounds should also be the same, if possible, but smaller close relatives can be used., if necessary.

 

A subwoofer may not be necessary if all the speakers are capable of extended bass but many people prefer (or are constrained) to use smaller speakers with a sub.  It can work just as well but adds complexity.  I do not use bass management but keep the subs for the ocassional 5.1 recording. 

[Kal Rubinson]

Gospel is that it is the same ITU Rec. 775 layout cited by Dolby (0deg for center, +/-30deg for L/R, +/-120deg for SL/SR) but it is based on the presumption that the recording/mixing/mastering was made with that as the target, as it is for movies.  Many of us have found that, for classical music where all the performers are up front, moving the SL/SR forward from +/-120deg to as much as +/-60deg can be advantageous.  Mine are just barely to the front of the listening position.

[Kal Rubinson]

11 minutes ago, SrMead said:

Sounds interesting!  Where?   I'm in Seattle.

RMAF is in Denver.

 

There  is a good alternative to the narrow selection of dedicated multichannel DACs.  See  https://www.stereophile.com/content/music-round-93-minidsp-ripping-sacds

[Kal Rubinson]

Potentially, but not at a competitive price.  Remember, one has many, many options among stereo DACs and all seem to have their advocates.  Using 3 CA DACMagics was a sweet spot, imho, but not as good as the exaSound.  Three Benchmark DAC3s was a different story but so is the price.

[Kal Rubinson]

2 hours ago, SrMead said:

Would you drive all channels with the same multichannel power amp, or would you separate out the channels? 

I use three identical monoblock amps for L/CR (ocassionally a three-channel amp) and a stereo amp for SL/SR.

2 hours ago, SrMead said:

How important is the center channel? 

For music, it should be identical to L/R or, at least, an adjacent model in the same range.  Avoid most dedicated center speakers.

2 hours ago, SrMead said:

What amp brands do you suggest?

???Tough to say.  Pick the speakers first. 

[Kal Rubinson]

Glad to hear of your new acquisition;  the exaSound DACs are the sweet spot in the MCH market.

 

Sadly, Fitzcaraldo215 is suffering from a serious health matter.  I do not know how he would feel about me mentioning this but his absence is certainly felt by those who know him and I cannot respond here without an abiding concern for him on my mind.

 

 

[Kal Rubinson]

10 hours ago, electro said:

I am having problems though. Loud crack through speakers when switching inputs, muting or using the adjustments to change  channel gain. Hiss audible from 12 feet away. Through ML CLX Arts and especially through the surround channels.  All amps connected with balanced cables. ....................................The MP1 is currently with Absolute Sounds (UK importer) who tell me it measures to spec!

I have been through all that.  AR has said the same to me (after an expensive tune-up).

10 hours ago, electro said:

My Multichannel sources are. Oppo 205. Exasound e28. Sony SCD9000ES.

I have used the same sources. 

10 hours ago, electro said:

Can you tell me what the AR guys did to lower the noise floor? Was it to lower the gain? Does it effect the sound quality? I would like to get the modification made in the UK if possible.

Part 1:  The noise floor solution lies not with changing the MP1 but with lowering the noise level through the system by lowering the gain of the power amps.

 

First, can you confirm that the noise is constant and not changed with the volume control as is the case with mine?  This will permit you to take advantage of the very output levels (~18V) that the MP1 is capable of.

If so, for every dB that you can lower the input gain of the power amp(s), you can lower the S/N of the output to the speakers.  John Atkinson tells me:  "Almost all amplifiers I have measured have voltage gains into 8 ohms of 25-29dB. The old THX standard was IIRC 27dB." 

 

The Parasound A31 (I have one, too.) is 29dB, as is the JC1, but the A31 also has a +/-6dB trim adjustment.  So, with the A31, you can turn the gain down to 23dB and turn up the output of the MP1 to enjoy a 6dB reduction in noise.  That said, the 6dB improvement is effective but marginal dependent on the speakers, some of which emphasize the HF noise.  For example, switching from the B&W 802D3 to the Revel Performa f228BE resulted in a drastic reduction of audible HF noise all by itself and the -6db lower gain was sufficient.

 

Your problem is that the JC1 has no such adjustment and the recommended solutions are to  (1) insert balanced line attenuators (-10 to -15dB) into the input jacks of all your amp channels or (2) get amps with lower (or adjustably lower) input sensitivity.   You may have an innate objection to using the attenuators but they are a simple way to demonstrate the validity of this approach. 

 

My solution came with my acquisition of a set of Benchmark AHB2 power amps which, like other amps from the professional world, have adjustable input gain options and, with them, I can get a ~20dB improvement in S/N which, effectively, makes the MP1 (and the system) dead silent.   Full story here:  https://www.stereophile.com/content/music-round-94-benchmark-marantz

  

[Kal Rubinson]

Just now, Kal Rubinson said:

I am having problems though. Loud crack through speakers when switching inputs, muting or using the adjustments to change  channel gain.

Part 2:  I used to have that problem and it is due to AR's decision to make each channel's circuit on a plug-in card which makes a multiplicity of sliding unsealed contacts with the main system board.  These contacts oxidize.   

 

I schedule an annual cleaning in which I (1) completely disconnect the MP1 from everything, (2) remove each of the six boards, (3) clean all the contacts on both sides of each board and the contact sockets on the main system board with DeOxit Gold and (4) reassemble and reconnect.  It takes me about 45 minutes and it keeps the switching silent.   You may need to do it more or less often.