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Final piece of the puzzle: digital correction in a suboptimal room


egoquaero

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Hey guys!
I'm in the process of upgrading/tweaking my system and there's one "final" piece of the puzzle I need to find.
 
Current setup:
  • Speakers: Klipsch Forte III
  • Subwoofer: Klipsch R-115SW
  • Amplifier: Hegel H190
  • DAC: Chord Hugo 2
  • Room size: 4*5 meters (roughly 13*16 ft)
  • Four wall-wall corners treated with GIK Tri-Trap Corner Bass Trap
  • Two front wall-wall-ceiling corners treated with GIK Soffit Bass trap
  • Side walls, rear wall and ceiling early reflection points treated with Monster bass traps
 
Considering the small size of the room and the big size of the speakers, I reached the conclusion that a quite heavy acoustic treatment was needed for both bass and mid high early reflections (as you can see from all the acoustic treatments in my setup). I'm still waiting for the panels to be delivered though (looking forward to!!).
My next move would be that of using digital correction as the final tweak to reach a flatter frequency response curve in my room (or at least in my listening spot). But how?
 
 
Few considerations:
 

1) I'd like to use my Chord Hugo 2 dac somewhere in the chain. I suppose the audio chain will be something like: Macbook --> DSP device --> Hugo 2 DAC --> Amplifier --> Speakers
2) I'd like to have only one digital-analog conversion (carried by Hugo 2)
3) I don't have a clear budget. I'm willing to spend money if the solution proposed solves my pain in a elegant way. Say 2000 usd max?
 

Questions:
  1. What DSP device/software would you suggest me to get?
  2. The Klipsch Forte III frequency response: 38Hz – 20kHz (+/- 3 dB)   How should I cross over to the subwoofer? At which frequency? At around 40Hz, 60Hz or 80Hz? And why?
  3. Where should the subwoofer fit in the chain in a way that it gets its input signal converted by Hugo 2?
  4. But then, if I place my subwoofer after the DAC in the audio chain, will the DSP device still be able to control the sub's input signal separately from the Forte speakers? (so that I'm able to have control on crossover points between speakers and sub)
  5. BONUS: It might be nice to have a system where I'm able to stream wirelessly from iPhone/Macbook (Airplay, Aptx) to the whole chain. Maybe a DSP device with integrated streamer? (furthermore consider that the Hugo 2 is able to do that via bluetooth aptx and the amplifier Hegel H190 is able to receive through Airplay and bluetooth aptx)
 
Thank you so much guys for your help!!
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Welcome.  I think you've done all the right steps first by trying to solve sound problems via speaker placement and room treatments before gently applying some DSP.  I'm not sure what you use to feed/stream to your Hugo2 today but if you are serious about #5, I recommend taking a look at Room EQ Wizard (REW) software for your Mac (free) and an under-$100 UMIK-1 calibrated USB microphone.  You can use this combo to create convolution filters (correction filters) that can be fed into various software streamers, Roon for example.  

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Your discussion sounds like a JRiver-type setup, i.e., not having a DAC in your "DSP device".  I've not used JRiver, but several people that I know and respect do use it, with two in particular that come to mind: etc6849 on this site and wesayso on diyAudio.  With JRiver, you can also flatten the phase of the loudspeakers and subwoofer(s) using digital FIR filtering and the power of your PC or an AES card, like Ellery (etc6849) used:

Here is a link to a summary of what wesayso has included in his (powerful) PC-based stereo line-array setup:  https://www.diyaudio.com/forums/multi-way/330741-preference-direct-radiators-27.html#post5731388

 

Knowing that these are probably well in excess of what you were thinking for "DSP devices", I think that it is worth your while to read on these setups and think about them (i.e., JRiver-based) to provide future growth capabilities in your approach.  This also dovetails with your wish to integrate streaming, etc.  It seems to me that the flexibility will be greatest using a PC-based system and a good AES/EBU interface or other type of soundcard of audiophile quality that wesayso used.  Performance/cost with these devices is extremely high.

 

My current setup (fully horn-loaded 5.1) is based around an AV preamp/processor that I've used for the past decade or so.  But if I had it to do from scratch again, I'd probably go a PC-based direction, assuming that I had all the codecs available for not only two channel audio, but also all the various flavors of video/movie codecs that are heritage formats for video/audio recordings (i.e., the reason for me to hang onto the AVP presently). 

 

Chris

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Hi Chris, thank you so much for your help as always!

So I took a look at Minidsp offerings with Dirac software and I found that the SHD studio might be the missing piece:

https://www.minidsp.com/products/streaming-hd-series/shd-studio

 

 

AUDIO CHAIN MAP (see attached image)

Screenshot-2019-06-24-at-16-28-21.png

 

As you can see with this structure:

  1. I keep Hugo 2 into the equation
  2. There's only one digital-analog conversion performed by DACs, since the SHD Studio dsp device is digital in and digital out

 

New questions:

  1. It seems that I need two DACs? One for the main speakers and the other for the subwoofer?
  2. Is there a way to make the Hugo 2 be the only DAC. So that the Hugo 2 receives two digital signals from the Shd studio and then produces two analog signals. One for the main speakers and one for the sub. This would be ideal, but I doubt it'd be possible.
  3. If point two is not possible, what would be a nice alternative?
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You'll need something to convert your third channel (a.k.a., subwoofer channel) into analog output to drive your subwoofer amplifier.  If you look, you can find DSP subwoofer amplifiers that can do those two functions (DAC to convert from AES3 [XLR] and a provide power amplifier for subwoofer) in one box, such as the miniDSP PWR-ICE125

 

You probably don't really want to go down the road of an analog summer from your left/right stereo channels to drive a mono subwoofer channel.  I wouldn't prefer that approach.

 

Chris

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I'm realizing now that... I have a spare Chord Mojo! I can use it as the second DAC to give that analog signal needed by the subwoofer.

Does it make sense? The Mojo's got two 3.5mm Headphone Jack outputs.

Is there a way to make this happen? Something that connects the Mojo to the subwoofer?

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So right now I have rca male-rca male cable for connecting the sub and the amplifier.
I would need a jack 3.5 male-rca male to connect the sub to the Mojo.

Do these items work?
https://www.amazon.it/metallo-masch...+maschio+mono&qid=1561456687&s=gateway&sr=8-8

https://www.amazon.it/Igreely®-pres...maschio+mono&qid=1561456736&s=gateway&sr=8-10

Not sure about the quality though...

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They look like they will work based on your descriptions of the mating elements.

 

I don't prefer using cable adapters myself, rather it's more reliable to use a cable that has the correct connectors on each end for the job.

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Cool thanks again!

 

With this structure is there a way to add a second subwoofer?

From the specs of the SHD Studio I see the following digital outputs:

Four channels of digital output

  • 2 x SPDIF on RCA connector / Isolated with digital audio transformer.

  • 2 x AES-EBU on XLR connector
  • Headphone amplifier output - CS43130 Headphone amplifier

 

So I wonder how I should connect the second subwoofer:

- First SPDIF of the SHD Studio to Hugo 2 --> Hegel H190 --> Klipsch Forte III

- Second SPDIF of the SHD Studio to Mojo --> Subwoofer

 

How should I do with the second subwoofer?

One solution would be the Mojo giving analog signals to both the subwoofers. However I won't be able to equalize the subwoofers separately...

Any suggestions?

   
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Another way to make things less complicated would be that of getting the Minidsp SHD with analog outputs as well.

And so it would be:

- Minidsp SHD digital out --> Hugo 2 --> Hegel Amp --> Klipsch Forte III

- Minidsp SHD analog out 1 --> Subwoofer 1

- MInidsp SHD analog out 2 --> Subwoofer 2

 

But then again... someone pointed out that Hugo 2's latency is pretty high and so the subs' sound might hit earlier than the main speakers' sound in an audible way...

Does this make sense?

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Thank you for your help. I wrote an email to Chord to see if they have a precise answer about this latency to know whether it'd be audible or not. If it's less than 30 ms, it should be correctable by the SHD Studio itself. Someone told me that the SHD Studio can adjust up to 30 ms.

 

All my connection concerns still remain... Why is it so complicated? :D 

So far, I haven't even figured out how to connect the SHD Studio to the Chord Hugo 2.. which digital output to which digital input? Which cable? 

We need a Steve Jobs to simplify the audiophile world... And then we wonder why young people are not joining... I'm 29 and definitely an exception :)

Edited by egoquaero
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Chord Electronics just got back to me and:

"According to engineering, Hugo2 has a 31ms delay at 44.1 Khz. If you wish to split the signal like that, it's a possibility that you will need to add a 31ms delay to the subs using the DSP"

 

Phew... 31ms should be manageable right?

Now back to the connection conundrum.

 

What’s the best way to connect the SHD Studio to the Chord Hugo 2?

https://www.minidsp.com/products/streaming-hd-series/shd-studio

 

I know that the SHD Studio’s got 4 digital outputs:

  1. FIRST output: SPDIF on RCA connector / Isolated with digital audio transformer
  2. SECOND output: SPDIF on RCA connector / Isolated with digital audio transformer
  3. THIRD output: AES-EBU on XLR connector
  4. FORTH output: AES-EBU on XLR connector

 

Chord Hugo 2 digital inputs are:
- Micro USB Input 768kHz (Probably wouldn't work with SHD)
- 3.5mm jack coaxial 768KHz/32-bit capable
- Optical Input 192kHz

  1. Am I able to use both SPDIF output and AES-EBU output to connect to Hugo 2?
  2. Which cable should I use?
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Kind of some funky, in terms of (traditional) home audio, hookups.  Are you sure it's so superior-sounding that it's worth the trouble integrating it?  It's doable, of course.

 

On 6/29/2019 at 6:29 AM, egoquaero said:

According to engineering, Hugo2 has a 31ms delay at 44.1 Khz.

 

With what settings?  And what's the latency at higher rates?

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Hi glens, well, there's something really sexy about the Hugo 2 :) Its transparency, the hyper details, its take on dynamics ... things I doubt the internal dacs of the Minidsp can keep up.

https://www.head-fi.org/threads/chord-electronics-hugo-2-the-official-thread.831345/page-809#post-14179639

Here, Rob Watts, the engineer behind Chord Hugo 2 states:

"Yes its about 31 mS for 48 kHz input, and it's down to the WTA tap length and 16FS oversampling on the first filter WTA1."

 

I actually don't know about the latency at higher rates and honestly I don't care as I'll only listen to CD quality.

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Okay.

 

You know, I also have Forte IIIs (congratulations on your fine choice!), and it may well be that you could simplify your task and forego the subwoofer.  Have you been listening to the speakers and feel the need for more deep bass, or are you yet earlier in the process of assembling this system?

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I know what you mean and I thank you for the suggestion. However I really can't let the subwoofer go... There's something magical about them. Audiophiles tend to snob them a lot: less transparent sound, muddy bass, less clear stereo image, less coherency, etc.    All true. But I feel like that people claiming this haven't really spent enough time (positioning, tweaking, EQ, etc.) and haven't set up proper acoustic treatments.

I listen mostly to jazz and electronic music. Electronic music often hits the area 20-40Hz and if you don't have a sub.. well, you enjoy half of it. Even with jazz, the sub just gives more soundstage and body impact. And I'm willing to sacrifice a little bit of transparency, coherency for those sub frequencies. It's a choice.

Everything in audio is a trade off as it is in life. :)

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