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Hi Pelliott,

I would advise that you take these measurements with a grain of salt. The measurements were taken indoors with little over 3.0ms gate time - so, again, limited resolution. It would be great if we can take these outside and prop them up on 12' ladder and take a couple of measurements that way - just to verify the above-provideded measurements.

Also - the above measurements were based on the new suggested passive crossover. What you may have heard in the spring had a different tonality. But in any case - yes - these do have rather wide horizontal dispersion, and certainly not bad vertical dispersion (- we are pretty good to +/-15degrees almost).

The tweeters naturally have an ever so slight rising response - and that is partially why a sightly off-axis (e.g., 10 or 20 degrees) listening axis was suggested (in other words - no toe-in). When listed slightly off-axis - the speakers are +/- 1.5db. Even on-axis, the rising response is not objectionable at all, because the ribbon just has this awesome clarity to it.

I would be curious to know your thoughts after a second listen (with the new crossover).

When I heard them in the spring David played them both with passive and active crossover. I preferred the passive being more musical, lees hifi.

Very good linearity.
Did you measure this in your place or Dave's?
Is any DSP like room correction in effect when measuring?
DSP is not necessarily bad, but from measurement perspective, if it is in effect you measured the music system as unit, not just the speakers.

This is a good example of how we listen/hear things differently. Charlie and I heard these speakers 2 weeks ago at Dave's and we both preferred the active crossover. Less veiled, better clarity and transparency though the speakers with either arrangement did not disappear. Sound could always be heard coming from the speakers, even on live recordings (in an acoustic space). That could be set-up, other equipment, or the speakers. I suggested Dave try working with Dhar as he's got a good measurement set-up and knowledge of massaging crossovers. I'm curious to hear the differences. Attached is the file of Dave's original passive crossover.

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?

Jim and Charlie are the only ones who have said anything remotely similar about the speakers not disappearing. In fact, quite the opposite. I invite anyone who's vaccinated to come and judge for themselves.

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I finished building the crossovers designed by Dhar. He started with my original crossovers and made changes that solved two issues. One was the bump starting at 1kHz. This is actually the drivers and the bump shows up on their spec sheet sweep. The other was flattening out the tweeter. Here are two sweeps from the listening position. The impulse window is wide open so you're seeing room influence, not just the speakers. Also, this is just the top box, no bass cabinet involved.

The original crossover:


The new crossover:

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I have too much stuff - https://www.pleasebuymystuff.com

There are many many traits of audio speakers. There is one speaker which excels in all traits.

To Jim, imaging behind the speakers is important. Your audio system may be doing many things right but imaging may not be up to Jim's standards. That information is good to know, but it should not bother you unless you also consider imaging behind the speakers is very important to you. In your basement, there is ample space behind and to the sides of the speakers making good imaging behind the speakers possible. Your old speakers used toto image behind the speakers when the audio material is acoustically placed between the speakers. When the material is placed to the sides, the depth of image used to decrease giving the feeling sound is coming from close to the speakers. Not sure if it still the same issue, but I would assume Spring would have made a big improvement in imaging, and of course the new speaks.

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.

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.