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PostPosted: August 31st, 2021, 10:24 am 
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Cogito wrote:
Yesterday, I spent sometime at Dave's. My take on his system:

Couple of us were concerned how well a 7" ribbon tweeter integrates in MTM configuration. It did integrate very well, there were no anomalies from the listening position.

The MTM system is very good overall. It images very well, vocals are very good and the highs are detailed and sweet.

In his system, the comparison between active and passive configuration is not valid as they are differently configured. In the active configuration, DEQX processor is used as active crossover. DEQX is limited to 96kHz bandwidth. So, Dave is feeding 96kHz upsampled material from foobar to DEQX, which divides the frequency ranges into highs and lows in digital domain and sends the data to 2 Spring DACs via SPDIF.

Holo Spring DACs are very good. We talked about the DAC and switched to passive crossover. This time, at my request Dave configured foobar to upsample to 384kHz and feed one Spring DAC via USB. The difference was immediately noticeable. Background became silent. We did not do detail comparison, but the obviously evident background noise is enough to convince me that using DEQX is not a good idea in a quality audio system. It was limiting the virtues of Spring DAC.

I have been using the DEQX for many years and it is completely silent. Can't understand why Dave's had noise.

Then Dave switched the passive crossovers and the mids/vocals became cleaner and the bass seemed to become tighter. Later Dave revealed this crossover is designed by Dhar where he fixed 1kHz bump and treble. Dhar did a very good job with the crossover.

When I use the subjective terms like silent, cleaner etc., they do not indicate an issue with the MTM speakers and those are readily noticeable. Very often we realize the deficiencies by their sudden absence.

In my opinion, DEQX should be dumped and pipe highest bandwidth digital stream to Spring Directly. I believe Spring Gen 1 is capable of 1.536mHz bandwidth.

Active system can still be implemented by building a passive line level crossover (PLLXO) between preamp and power amps.
https://www.t-linespeakers.org/tech/fil ... eHLxo.html

Overall, very good MTM speaks.


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PostPosted: August 31st, 2021, 11:06 am 
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Cogito wrote:
Then Dave switched the passive crossovers and the mids/vocals became cleaner and the bass seemed to become tighter. Later Dave revealed this crossover is designed by Dhar where he fixed 1kHz bump and treble. Dhar did a very good job with the crossover.

And now you know why this "Luddite" favors passive over digital. And now you why the $6-figure speakers out in the rarified very-rich audio world do not have electronic crossovers. :character-oldtimer:

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PostPosted: August 31st, 2021, 11:31 am 
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tomp wrote:

I have been using the DEQX for many years and it is completely silent. Can't understand why Dave's had noise.

[/quote]


Noise levels in DEQX are not at objectionable levels, in our short session they went undetected until DEQX is removed from the signal path.

Checked DEQX website, they don’t seem to be publishing the noise and jitter figures. Unless you replace DEQX with a quality DAC which is far superior to DEQX, you may not realize DEQX’s noise. Come to think about it, not just the noise floor but jitter and linearity issues may be at play here.


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PostPosted: August 31st, 2021, 12:01 pm 
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Cogito wrote:
tomp wrote:

I have been using the DEQX for many years and it is completely silent. Can't understand why Dave's had noise.




Noise levels in DEQX are not at objectionable levels, in our short session they went undetected until DEQX is removed from the signal path.

Checked DEQX website, they don’t seem to be publishing the noise and jitter figures. Unless you replace DEQX with a quality DAC which is far superior to DEQX, you may not realize DEQX’s noise. Come to think about it, not just the noise floor but jitter and linearity issues may be at play here.[/quote]

Dave's DEQX doesn't have noise. Plus, we were listening through the same DAC whether or not the signal was going through the DEQX or not.

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PostPosted: August 31st, 2021, 12:31 pm 
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DaveR wrote:

Dave's DEQX doesn't have noise. Plus, we were listening through the same DAC whether or not the signal was going through the DEQX or not.


Holo DACs have true Non-Oversampling (NOS) Mode. In the NOS mode, Spring tries to faithfully convert the incoming digital signal into analog signal. No filters, dithering or upsampling is done. In other words, a true NOS mode is Garbage-in Garbage-out (GIGO) mode. Any anomalies introduced by DEQX in the digital domain are faithfully reproduced by Spring in NOS mode.

The fact that I heard lower noise after removing DEQX from the signal path points to DEQX as the culprit.


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PostPosted: August 31st, 2021, 2:18 pm 
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I have always maintained that I heard something with the Deox that I did not like. Both with Dave’s system and with Tom’s. I know it’s great tech and it’s fun fooling around with all the adjustments.
But for me it’s the sound that matters, and to me things did not sound good to me.


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PostPosted: August 31st, 2021, 3:06 pm 
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Different strokes for different folks. Just a few reviews of the DEQX. When John Atkinson first heard what it could do his reply was "gobsmacked!" But it is not everybody's cup of tea.


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DEQX reviews.pdf [132.97 KiB]
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PostPosted: August 31st, 2021, 3:44 pm 
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Cogito wrote:
dkalsi wrote:

This was at my place; however, since the measurements are gated, room interferences have been removed.

No DSP

I suggested to David to have a listening party with fellow forum members while employing the new crossover, which has been voiced to provide a more neutral presentation. People can then provide suggestions if they feel certain frequency bands need to be EQ'd (boosted/attenuated). The speaker should respond well to EQ (note the even spacing in the provided polar response), with the exception of a narrow range that is impacted by diffraction issues (2Kz - 3.5Khz).

After the group is in agreement, we can then modify the passive crossover to similar tonality (*noting there is a limitation to how far you can go with passive).

Who knows, we may end up far from flat response, and that's perfectly fine. Common as it may be, it's not a hard and fast rule that every person must prefer a flat speaker.

In fact - it took me some time to adjust to more neutral speakers. For the longest time I enjoyed more colored speakers (e.g., Klipsch, etc.) - and still do from time to time. Giving neutral speakers a chance is something new to me, and I'm enjoying it.

If I'm not mistaken, I believe David plans to employ a bass cabinet below a certain frequency, incorporated with an active crossover. I would suggest he voice the passive crossover in the top cabinet to provide a neutral response, and then employ active EQ to taste.

I think they sound really nice. I never heard them with the original crossover, only took sine sweeps, but I did get a chance to listen to the new crossover for a short time and liked what I was hearing. The woofers blend really well with the ribbon - even as you walk up to the speaker - you can tell there is nice integration between the components (no sudden jumps from tweeter to woofer / vice versa).

Since Jim and Charlie were last to listen to them - I'm curious to hear their thoughts on the revised crossover. They look good on paper - but the true test would come from listener feedback.


Did you measure both top and bottom cabinets together? If so, where did you position the mic?


Based on the low FR response in th graphs, I assumed you measured both top and bottom cabinets together and didn’t understand how that is possible with drivers firing in different directions. Dave told me you measured only the MTM cabinet. That answers.


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PostPosted: September 1st, 2021, 10:05 am 
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tomp wrote:
Different strokes for different folks.


Thats right.

We all strive to improve our systems. Sometimes, our own ears are sufficient to judge our systems. That is the purpose of this thread.
To my ears (and Paul's), Dave's system subjectively sounds better without DEQX in the signal path.


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PostPosted: September 1st, 2021, 10:12 am 
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When it is your system, if whatever path you take does not float your boat, why bother. Go with whatever works for you regardless of what others say.


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