Broadband DSP Correction
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Joined: Mar 2001
Posts: 1,387 Likes: 8
President connoisseur
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OP
President connoisseur
Joined: Mar 2001
Posts: 1,387 Likes: 8 |
The introduction of the LFR1100 brought about a lot of questions about using a Broadband Digital Signal Processor (DSP) between your pre-amp and your main amp in other speaker models for the purpose of smoothing out small anomalies in the amplitude response. These are referred to as ‘High Q’ corrections to the response curves. In many ways a speaker’s amplitude response curve could be divided into two Q groups: • The Low Q, which deals with amplitude differences over a wide frequency band • And the High Q, which deals with amplitude differences within a narrow frequency band. Audibility of small differences in amplitude over a wide frequency band (Low Q) is very noticeable and needs to be carefully addressed in the design on the speaker. On the other hand, audibility of small differences in amplitude over a narrow frequency band (High Q) is not very audible. The DSP in the LFR1100 already incorporates this High Q correction across the frequency band. Low Q correction is done in using the passive crossover network located inside the cabinet. In response to all these inquiries we have created a DSP component that is able to do this High Q correction to the M80v3, VP180v3, VP160v3, and recently announced M100. The graphs below show the difference in the Listening Window response to an M80v3. Since the correction applied from the DSP is concentrated completely in the High Q group we would recommend this product for the discerning audiophile only as the audibility of this correction will be quite subtle. The other feature on the DSP for the LFR1100 is the Boundary Switch, which is used to compensate for having your speakers very close to walls or large cabinets. Even though the M80s and M100s are not omnidirectional the proximity to boundaries still does have an effect in the lower frequencies. For that reason we have included a Boundary Switch on the DSP for these models also which should be experimented with in your room as the effect of the rear wall proximity will vary from room to room. We will have these DSP Correction boxes available at the end of August. For anyone purchasing one of these to be used with their current M80v3 and VP180v3 we will need you to provide us with the serial numbers as there have been modifications to them along the way. We have created a spot to do this during the order process. The cost of the DSP box will be $950 for your two main speakers and $1,260 if you wish to add another DSP in the box for your VP180 or VP160. We will be doing a pre-release promotional price of $690 and $890 respectively from now until the end of July. Broadband Digital Signal Processor Uncorrected M80 Corrected M80
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Re: Broadband DSP Correction
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Joined: Oct 2012
Posts: 2,021 Likes: 1
connoisseur
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connoisseur
Joined: Oct 2012
Posts: 2,021 Likes: 1 |
Would the difference be more pronounced on lower quality recordings, radio broadcasts etc?
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Re: Broadband DSP Correction
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Joined: Mar 2001
Posts: 1,387 Likes: 8
President connoisseur
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OP
President connoisseur
Joined: Mar 2001
Posts: 1,387 Likes: 8 |
The difference should remain the same no matter the type of recording you are playing.
Ian Colquhoun President & Chief Engineer
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Re: Broadband DSP Correction
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Joined: Feb 2009
Posts: 3,466
connoisseur
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connoisseur
Joined: Feb 2009
Posts: 3,466 |
I guess this is as good a thread as any to ask about a particular technical detail of the DSP box.
At what sampling rate does it operate internally? And how does it deal with any input signal that is at or above it's Nyquist limit?
I'm perfectly OK with a sampling rate in the 40 kHz range. Though, unless there's a steep decimation filter before the ADC, any Blu-rays foolishly encoded at 96 or 192 kHz may cause audible aliasing artifacts when resampled at that lower rate.
Pioneer PDP-5020FD, Marantz SR6011 Axiom M5HP, VP160HP, QS8 Sony PS4, surround backs -Chris
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Re: Broadband DSP Correction
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Joined: Dec 2001
Posts: 334 Likes: 5
Axiom Engineer devotee
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Axiom Engineer devotee
Joined: Dec 2001
Posts: 334 Likes: 5 |
I guess this is as good a thread as any to ask about a particular technical detail of the DSP box.
At what sampling rate does it operate internally? And how does it deal with any input signal that is at or above it's Nyquist limit?
I'm perfectly OK with a sampling rate in the 40 kHz range. Though, unless there's a steep decimation filter before the ADC, any Blu-rays foolishly encoded at 96 or 192 kHz may cause audible aliasing artifacts when resampled at that lower rate. Hi ClubNeon, As you are likely aware, there are three main components to the processing chain inside the DSP box: ADCs, DSP core, and DACs. Both the ADCs and DACs are Sigma-Delta, 24-bit, and operating at a 96kHz sampling rate. Inside the DSP core itself most of the processing instructions are double precision, 56-bit (28-bit × 28-bit multiplier with 56-bit accumulator). The DSP core is capable of performing 50 MIPS and we are utilizing a fraction of the available headroom. There is an active anti-aliasing filter at the input to the ADCs. I hope that answers your questions!
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Re: Broadband DSP Correction
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Joined: Feb 2009
Posts: 3,466
connoisseur
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connoisseur
Joined: Feb 2009
Posts: 3,466 |
Not only did that answer my question, it's the answer I wanted to hear.
Pioneer PDP-5020FD, Marantz SR6011 Axiom M5HP, VP160HP, QS8 Sony PS4, surround backs -Chris
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Re: Broadband DSP Correction
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Joined: Jun 2003
Posts: 8,488
axiomite
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axiomite
Joined: Jun 2003
Posts: 8,488 |
If Chris is happy, then I'm happy.
Geeks.
bibere usque ad hilaritatem
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Re: Broadband DSP Correction
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Joined: Jul 2013
Posts: 14
frequent flier
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frequent flier
Joined: Jul 2013
Posts: 14 |
So what this DSP box is doing is to convert the analog signal in digital (with the ADC chip), process it, and reconvert to analog (with the DAC chip) and give the corrected signal back to the amp?
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Re: Broadband DSP Correction
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Joined: Mar 2012
Posts: 286
local
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local
Joined: Mar 2012
Posts: 286 |
The one for my LFRs only has analogue (though both RCA and XLR). I can't see how this would change in the new version. In fact the specs only mention the RCA and XLR inputs.
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