New time-based room correction device available

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ekovalsky

New time-based room correction device available
« on: 6 Oct 2005, 06:58 pm »
Copland DRC 205

http://www.copland.dk/pdf/Copland_DRC_205_Product_sheet_web.pdf

This uses the Dynaton time-based room correction system.  It runs fully automated without a PC, or with full user control using PC-based software.  Its algorithm is fundamentally different than current offerings from TacT and DEQX, having advantages of (1) not altering the original music signal and (2) fixing nulls.  It performs correction primarily by supplementing the music program with calculated phase and delay signal to offset room peaks and nulls.  Unlike the TacT and DEQX, and other EQ based systems, there is no significant loss of resolution or maximum SPL when correction is active.

Same technology is also the basis of the next generation Lyngdorf Audio (formerly TacT dK) products which will appear early next year.

Copland does not currently have a USA distributor.  The Canadian distributor is http://www.divertech.com same as for
Antique Sound Labs and Audiostatic.  MSRP is around $1750.

Unfortunately it seems that only analog RCA inputs and outputs are provided on this unit.  Hopefully the built-in DACs are up to task.  A digital input sure would have been nice since it could avoid DAC (in source) and ADC stages...  probably something that could be modded in but I'm at a loss as to why the manufacturer wouldn't include it.

Since the major benefits of correction (with a properly designed speaker) are in the bass range, this device would lend itself well to a biamp configuration where it is used on the bass section only.

Jon L

New time-based room correction device available
« Reply #1 on: 6 Oct 2005, 07:28 pm »
Why on earth would they market a product like this without digital in/out?  I was getting excited reading about this until I realized this.  They can skip the AD converter and DA converter and sell the unit cheaper, which will increase market share.  Those who need AD/DA can purchase it as an option.  

Disappointed...

ekovalsky

New time-based room correction device available
« Reply #2 on: 6 Oct 2005, 07:56 pm »
Quote from: Jon L
Why on earth would they market a product like this without digital in/out?  I was getting excited reading about this until I realized this.  They can skip the AD converter and DA converter and sell the unit cheaper, which will increase market share.  Those who need AD/DA can purchase it as an option.  

Disappointed...


I couldn't agree more.  It is plain silly to force analog conversion of the redbook source, then transmission over an analog interconnect, then conversion back into digital for DSP.  Sure this arrangement is currently required for turntables and SACD/DVDA players, but what is the percentage of vinyl and hi-res digital in most of our collections ?  For me it is about 1% :!:  The rest is plain redbook CD.

I'm very fond of the TacT amps which are best driven by their digital input.  But they are bettered by the best analog tube and solid state amps, so having analog outputs is a nice feature.  But I don't like being captive to the onboard DAC, good as it may be.  It is far preferable to also have a digital output so the owner has the flexibility to use a TacT or Behold (or other future digital-input amp), or the DAC of their choice for an analog power amp.

I really like how TacT offers their units.  Cheapest form is a stripped down unit with only digital-in, digital-out and no analog at all.  Analog inputs and outputs, if needed, are available at extra cost and can be easily installed by the owner.  It is worth noting that the all-digital RCS 2.2X sounds best when the 12v limb of the power supply is disconnected.  All the digital circuits run on the 5v output, so the 12v is needed only for ADC and DAC cards, and also the mic preamp card.  If you use the TacT RCS and amps, after you make measurements unplug the 12v lines on the umbilical cable from the power supply for a free and quick upgrade!

DEQX has digital inputs and analog ins/outs standard, so you are paying for the ADC and DAC stages whether you want to use them or not.  
While digital outputs are an available option, they will cost you $500  :x  What I'd like to see them offer is a PDQ-2.6D with only digital ins/outs that costs about $500-1000 less than the standard unit.

Now keep your eye out for the Lyngdorf RCS 2 + 2 which should offer all the features of this Copland unit and more, including digital inputs and outputs, as well as DSP crossover functionality, volume control, adjustable delay, etc.  It is their replacement for the 2.2X and does use the new Dynaton correction system.

There is a rumor that TacT USA has a updated RCS in the works, but I'll believe it when I see it.  My guess it will use the same EQ-based correction the current units have, since that is Boz's brainchild.

jermmd

New time-based room correction device available
« Reply #3 on: 6 Oct 2005, 07:58 pm »
Are you saying that there's no A to D and D to A conversion? I think that's great if you're using a high end CD player or external DAC. This also is not a preamp. It can be added between your existing preamp and amp. It doesn't require a major change in your present system like the Tact does. Luckily, the Tact happens to be both an exceptional DAC and an exceptional Pre.

csero

Re: New time-based room correction device available
« Reply #4 on: 6 Oct 2005, 08:11 pm »
Quote from: ekovalsky
having advantages of (1) not altering the original music signal and (2) fixing nulls. ...


quite possible with additional channels, but impossible just using the 2 main speakers.

Quote from: ekovalsky

 It performs correction primarily by supplementing the music program with calculated phase and delay signal to offset room peaks and nulls. ...


Since when supplementing is not altering??? BTW the method above is the same as the impulse measurement based inverse filters, aka " eq based RCS".

ekovalsky

New time-based room correction device available
« Reply #5 on: 6 Oct 2005, 08:42 pm »
Quote from: jermmd
Are you saying that there's no A to D and D to A conversion? I think that's great if you're using a high end CD player or external DAC. This also is not a preamp. It can be added between your existing preamp and amp. It doesn't require a major change in your present system like the Tact does. Luckily, the Tact happens to be both an exceptional DAC and an exceptional Pre.


From your CD player, the analog signal is converted into digital within the DRC 205 (it does use a DSP engine) and then is converted back into analog before output.  Alas with the Copland there is no way to directly feed the digital stream from your transport or PC-based source to the DSP engine.  If the DRC 205 had a digital input, the DAC stage in the source and the pre-DSP ADC stage could be eliminated.  Don't ask me why the digital input was omitted, it makes no sense to me.

Quote from: csero
quite possible with additional channels, but impossible just using the 2 main speakers.  Since when supplementing is not altering???


Ok, you're correct on that point.  It would be interesting to have an option to separate the "correction output" so that it could be fed to another set of speakers, instead of it being combined with the main output.

Quote from: csero
BTW the method above is the same as the impulse measurement based inverse filters, aka " eq based RCS".


Not the way I understand it.  The TacT measures in-room response, and basically uses its inverse to create an infinitely variable parametric EQ filter to conform the output to a target set by the user. Let's say there is a +12dB peak with Q=4 at 40hz.  The filter will apply -12dB at 40hz with Q=3.  In practice this happens at every frequency and it works very well for peaks.  Nulls are another story -- if it measures -12dB at 60hz it will try to compensate by adding +12dB in the filter.  But this will not fix the null, plus it will probably result in clipping.  Nulls need to be minimized by moving speakers and listening position, then the user has to bypass correction around the remaining nulls by altering the target curve and/or using crossovers to conform the target to measured response.

I think the DEQX works similarly to the TacT.

The Dynaton time-based system, used by Copland and Lyngdorf, works by adding signal of calculated delay and phase, and of the appropriate amplitude, to negate room effects.  Instead of using a filter to change the frequency response, and attenuating frequencies at room resonances, like the TacT/DEQX, it will create "echoes" of the same frequency that disrupt the formation of resonant nodes and quarter wave cancellations.  It is not dissimilar to the double bass array system I've posted about before, but it doesn't require additional speakers.

Since the suppression signal should not have to be any stronger than the original signal, I would think that the headroom needed for this system would be around 3dB. It is a lot higher with the TacT, typically 6-8dB -- if your TacT correction curve only needed 3dB of "play" you probably don't need room correction in the first place!

In reality my guess a combination of both correction algorithms will probably work best, but of course we'll have to wait and see how these products actually work and sound in a real system.

csero

New time-based room correction device available
« Reply #6 on: 6 Oct 2005, 09:04 pm »
Quote from: ekovalsky
Ok, you're correct on that point. It would be interesting to have an option to separate the "correction output" so that it could be fed to another set of speakers, instead of it being combined with the main output.
...

It is not that simple. It would lead to a recursive correction algorhytm - correcting the correction signal etc. Also, you have to deal with the directionality of hearing.

Quote from: ekovalsky
Not the way I understand it. The TacT measures in-room response, and basically uses its inverse to create an infinitely variable parametric EQ filter to conform the output to a target set by the user. Let's say ...


What you describe is not RCS but parametric EQ.
In and RCS you measure the impulse response of the room/speaker combo, FFT it to visualise the impulse response in the freq domain, create the inverse response and FFT again to convolve with the new impulse response. The new impulse ( if the original measurement was long enough) is exactly what you mention as "works by adding signal of calculated delay and phase, and of the appropriate amplitude, to negate room effects".
How much headroom you need is still depends on how bad is the original response and  what was the target in the inversion. Also a big problem that the original and the correction signal is coming form the main speakers, while the room response - which was flattened into a single impulse response - is actually a full sphere response.

ekovalsky

New time-based room correction device available
« Reply #7 on: 7 Oct 2005, 02:32 am »
csero,

I'm not convinced the TacT software does any significant manipulation of the signal in terms of phase/delay.  It seems to rely on what is basically a stepless variable parametric EQ.  Some of the new TacT amps -- TDA2200 and Millenium mk3 and 2150X -- offer room correction which is purely parametric EQ but, unlike the RCS, limited to a finite number of bands (twelve I think).  More sophisticated room correction has been promised for these amps but has not yet materialized into actual product.

Someone correct me if I'm wrong about this.  If the TacT RCS software does indeed perform time based room correction with delay/phase manipulation please explain the specifics.

The DEQX may be totally different, I'm not familiar with its software other than screencaps I've seen in the 6moons review, from a few owners' systems, and from the manual.

The measurement process is as you describe of course.

Edit -- the TacT "Dual Domain" can show the measured impulse response,  frequency response from FFT, and the convolved correction filter.  I've used the impulse response to "time align" my system by adjusting delay to the woofers and optimizing toe in for the mid/tweeter array.  I've yet to see any evidence that the TacT does anything automatically to manipulate the impulse response.

JoshK

New time-based room correction device available
« Reply #8 on: 7 Oct 2005, 03:35 am »
I know from some posting on the DEQX forum that the DEQX does work with the impulse response and makes corrections there.  I know because there was a Japanese grad student that was asking questions of the programmers and they were discussing the merits of the various methods.  I can't say I really understood any of it as I have never read up on the methods, or even the concepts involved.

Bill Baker

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New time-based room correction device available
« Reply #9 on: 8 Oct 2005, 11:24 pm »
I am inquiring on the availability and pricing of the Copland unit and may bring one in for evaluation.
 I'll keep you posted.

JohnR

New time-based room correction device available
« Reply #10 on: 9 Oct 2005, 12:10 am »
Quote from: JoshK
I know from some posting on the DEQX forum that the DEQX does work with the impulse response and makes corrections there.


Josh, where is the DEQX forum? (Don't see anything on their site.)

JoshK

New time-based room correction device available
« Reply #11 on: 9 Oct 2005, 12:16 am »
John,

The DEQX is a mailing group really, not a typical forum.  Its actually the beta testing forum and you need to be an owner, but if you asked nicely they might add you anyway.  I'd email DEQX and ask about it.

JohnR

New time-based room correction device available
« Reply #12 on: 9 Oct 2005, 12:56 am »
Ah, OK. Thanks, I should probably stay out if it's not public access :)

ekovalsky

New time-based room correction device available
« Reply #13 on: 12 Oct 2005, 12:21 am »
Quote from: Response Audio
I am inquiring on the availability and pricing of the Copland unit and may bring one in for evaluation.
 I'll keep you posted.


Thanks Bill.  As you obviously have an existing relationship with Divertech, you are an ideal person to get one in a timely manner.  Please keep us posted!

ctviggen

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New time-based room correction device available
« Reply #14 on: 12 Oct 2005, 04:27 pm »
csero,

Could you clarify this:  

Quote
In and RCS you measure the impulse response of the room/speaker combo, FFT it to visualise the impulse response in the freq domain, create the inverse response and FFT again to convolve with the new impulse response.


Once you create the inverse response, on what signal do you perform the FFT?  Do you take the current signal, perform an FFT thereon, and then convolve the resultant frequency domain signal with the new impulse response (in the frequency domain)?  (And if you do that, why not just multiply in the time domain, as that's convolution in the frequency domain?)  Or perhaps you perform an iFFT on the inverse response and multiply the result of the iFFT with an incoming digital signal?  That would also get you convolution in the frequency domain.

For the DEQX, it has seven adjustable filters (EQ).  These are adjusted to the peaks/nulls.  Or at least that I get by reading their literature.

ctviggen

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New time-based room correction device available
« Reply #15 on: 12 Oct 2005, 05:25 pm »
Dang grammar!  That should say, "that's what I get by reading their literature."

Bill Baker

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New time-based room correction device available
« Reply #16 on: 15 Oct 2005, 01:16 am »
Hello All,
  The Copland DCR-205 will sell for $2500. They will become available around the first week in November. I am considering putting an order in for one to evaluate. I'll do a bit moreresearch now but I have heard from a select few that have auditioned it (in other countries) that were very impressed. I do not know if these people were consumers or various dealers.
 I guess only time will tell.
 I am also considering bringing in the Copland CD player for evaluation. Anyone have any feedback or experience with these or Copland products in general? I will admit that I do not have much experience with Copland products to share.

ekovalsky

New time-based room correction device available
« Reply #17 on: 15 Oct 2005, 01:56 am »
$2500 seems a bit high.  The UK dealer has them for 1,250 pounds, including VAT.  Without VAT it is about 1,064 pounds, or $1,882.  An italian dealer has them for 1,440 Euro, probably exclusive of VAT.  Shipping costs to the USA are of course not included in those figures.

I've never heard any of the Copland gear, but the line has a clean look that reminds me a bit of the Stello products.  Besides the DRC-205 and the CD player there are 2ch and 5ch tube preamps, 2ch and 5ch power amps, and a tube integrated.  

If the equipment is indeed good, it may be worth adding to your line card.  As far as I know you would be the only USA dealer.