Fullrange speaker project based on Markaudio CHR-120

[ppataki]

For a more one-to-one comparison of the impulse and step, identical EQ settings should have been used. Some of the difference in the phase response could possibly be because of the impulse centering and timing reference -- if you are using a USB mic, the clock timing can still drift even with a reference "chirp" -- repeat measurements may be necessary to check for consistency. It seems strange for your other amp to shift the phase by that much.

Already moved back the rig downstairs
I will perform additional measurements with the new amp once I can order it (waiting for EU stock....)

 

[fineMen]

Already moved back the rig downstairs
I will perform additional measurements with the new amp once I can order it (waiting for EU stock....)

Bad news first, with all my apologies. The speakers are well too small to deliver. You'll be bothered with distortion, and more prominent, but mostly accepted by many due to lesser experience with good speakers, intermodulation. See https://www.audiosciencereview.com/...research-lgk-2-0-speaker-review-a-joke.34783/.

O/k, now the good news. One valid caveat against wideband speakers is the beaming at higher frequencies. From some size-dependent range on, the radiation to the sides and up/down will rapidly decrease. One might argue that with a desk-top arrangement the position of the head is well determined. You mount the speakers angled towards Your ears. But still the grand total balance of sound in the room will be affected. It is too 'dark'. Sitting in the so called near field additionally increases the so called 'focus'. But conversely that might generate stress, because if You move, the stereo perspective changes a lot more than with a wider stereo base and a greater distance. To re-adjust the hearing's expectations every other minute costs for sure time and mental effort.

The problem can be solved. Just consider to use additional tweeters. No--not to be mounted in the wide-band box, but positioned independently. I think of a pair of tweeters driven with opposing phase (+/-) mounted back to back. This would make a dipole, right. This arrangement goes in the middle between the wide-bands, facing sidewards. Your head resides in the 'null' of the dipole; no sound would directly be radiated towards You. But the sidewalls get the full program and reflect it in all the room, enlightening the reverberation. That reverberation will keep You magically at You place, even if You move ;-) It ankers the hearing in the real world surrounding You.

I just tested this at my home, supplementing quite regular two way speakers. Again, measured, the direct sound at the listening position is not affected. But sidewards the additional tweeters support the soundfield by 6..8dB. It is like the original two-way had a tweeter of less than 10mm (3rd of an inch) diameter. This quite wide radiation pattern matches that of the 5 inch woofer in the very small box.

I) no stereo needed for the supplementing tweeters, because it is just about reverberation, which by definition(!) doesn't comprise directional cues
II) high passed at about 7kHz distortion and other cost-generating properties are of no concern--mine cost 3$ (three) each with TotalHD < 0,15%
III) size can be very small, 4x4x2cm^3 actually
IV) level adjustment is crucial, depending on individual taste

Such tech was used in the late 60s and early 70s to enhance the performance of, even back then, out-dated designs with cone tweeters. One could happily buy bad renditions of the concept everywhere. But done right, the stereo effect is not diminished, promised. To really have stereo, You have to sit within +/- 10° of the symmetry line. There the direct radiation always wins. Only off that line the reverberations chimes in, but then the stereo, as it was meant to be, is anyway lost. Then the well balanced sound field is prime, established by additional tweeters. It is time to revive the idea.

 

[ernestcarl]

Bad news first, with all my apologies. The speakers are well too small to deliver. You'll be bothered with distortion, and more prominent, but mostly accepted by many due to lesser experience with good speakers, intermodulation. See https://www.audiosciencereview.com/...research-lgk-2-0-speaker-review-a-joke.34783/.

This whole thing with IMD being a huge problem is somewhat overblown. If low bass distortion is an issue, simply use DSP to apply a cut off. My dinky little Fostex 6301 (no additional EQ applied) didn’t exhibit same kind of weird distortion when pushed loud using the same example track. With certain other tracks, and at loud enough SPL, sure… one can start to hear IMD, of course — but the vast majority of the time the even the smaller 6301 when used normally performs just fine.

The reviewed single driver speaker sample by Amir just happened to be especially awful in that case, but it doesn’t mean all single driver designs can’t perform good enough for their intended application(s).

—

Hmmmn… I do like the idea of the supplemental (optional) extra tweeters. It may be worth experimenting with… even just for sake of finding out what it sounds like.

 

[fineMen]

This whole thing with IMD being a huge problem is somewhat overblown. If low bass distortion is an issue, simply use DSP to apply a cut off. My dinky little Fostex 6301 (no additional EQ applied) didn’t exhibit same kind of weird distortion when pushed loud using the same example track. With certain other tracks, and at loud enough SPL, sure… one can start to hear IMD, of course — but the vast majority of the time the even the smaller 6301 when used normally performs just fine.

IM may itself been obscured by nasty HD and even linear distortion, common to wide-band drivers. A bad design would pull the attention to any other than the music. The mind fumbles with the evaluation of such distractions? Maybe because of the hypothetical effect the IM of the cited "fun" speaker became obvious--at least the frequency response was quite good by any means. It left processing power to find the actual IM?

Objectively, some designs are so bad, compared to readily available mediocre designs today, that one might wonder what both sides, customer and manufacturer were thinking

Hmmmn… I do like the idea of the supplemental (optional) extra tweeters. It may be worth experimenting with… even just for sake of finding out what it sounds like.

Yeah, its cheap and simple. But same as with subs: do not overdo. Some kind of measurement equipment is necessary.

 

[ppataki]

I have measured the IMD of my MCLA system, see it here: https://audiosciencereview.com/foru...250tc-project-measurements.35301/post-1232523

I will measure the IMD for this system too once I get the new amp (EU stock shall become available next week)

 

[fineMen]

I will measure the IMD for this system too once ...

If You do, please, for Your own good, review Your methodology. Just kidding, for my good ;-)

With the MCLA it looks like You were feeding the speaker with a series of harmonics. That wasn't my first attempt. What I found quite, and in case even shockingly revealing is to basically excite the system with a deep bass note like 40..80Hz and then go through additional higher frequencies at lower level. You will easily detect the inevitable problems with the surround at about 600Hz and the progressively increasing shmeer above 1kHz. The usually advised 'multitone' has way too little low content as to actually stress the system. You don't have to sell the product ;-)

 

[fineMen]

... 'multitone' has way too little low content as to actually stress the system. You don't have to sell the product ;-)

Addendum, playing around with intermodulation. How bad it really is.

Box 9liters of volume, sealed with a 7 inch bass equaized flat, plus 4inch wide band, crossed over @400Hz using Butterworth 12dB slopes.

Bass alone plays 40Hz with about 3% distortion, which is not that bad. Following two graphs which depict the IM with additional 300Hz and 900Hz:

Same as above, now midrange driver added:

Thing is: With 8% and more the basses IM gets so high, that is copies through to the midrange. It dominates the total IM of both, bass and mid-speaker combined even one octave higher than the x-over frequency.

Only with an 18dB / Octave slope the IM goes down to a just acceptable 1%.

If You think the bass was cheap, it isn't. In terms of distortion, excursion and the like it performs just excellent ... now think of using a tiny 4 inch full-range for bass and mids and treble simultanously.

 

[ppataki]

Finally my Sabaj A30A has finally arrived earlier this week
I have already commented in the relevant thread that I absolutely love how it sounds and it is totally on par with my NC250MP and Topping DM7 combo....
And of course it supersedes my Loxjie A30 by not just a bit

After playing around with my usual DSP plugins I managed to get this response:

In the bottom end I apply a 24dB/octave HP filter at 27Hz (not shown above)

Phase looks nice in my opinion:

And here is the IMD too:

It is pretty nasty around the 100Hz region....

Overall I am very pleased with the sound, I think this project has come to an end - time to look for the next one!

 

[fineMen]

And here is the IMD too:

View attachment 238979

It is pretty nasty around the 100Hz region....

Overall I am very pleased with the sound, I think this project has come to an end - time to look for the next one!

Congrats! Its nice to get something finished. Alas, I'm tempted to comment Your IM measurements again. Obviously You feed the speaker with selected harmonics, which obscures parts of the IM spectrum:

Excitation tones 20 / 40 / 80 / 160 ... n = n(-1) * 2

E/g IM due to 40Hz component combined with 160Hz:

160Hz +/- 40Hz, 160Hz +/-(2*40Hz), 160Hz +/-(3*40Hz) ... = 120/200Hz, 80/240Hz, 40/280Hz ...

where 80Hz and 40Hz are already part of the original excitation spectrum. Other IM product double like 200Hz = 160Hz + 40Hz = 80Hz + 3*40Hz and so on.

The more critical caveat is the sound pressure level the speaker was forced to produce. From the very low percentage of IM I would conclude, it was pretty much low. 70dB at 30cm distance maybe?
Reiterated, I've got real pro, top of the bunch 12inch speakers that show, at reasonable SPL for home use alone, IM like 0,2%. The microphone may contribute like 0,1% to that. But Your's is 0,1% with a 4inch wideband--unbelievable. Even the Purify models with latest tech applied show up with some 3% if driven to just common household levels ( please compare: https://www.erinsaudiocorner.com/driveunits/purifi_4/ )

I wonder why You didn't take my hints from above seriously, post #27. I assure You, I'm not an amateur.

 

[ernestcarl]

Finally my Sabaj A30A has finally arrived earlier this week
I have already commented in the relevant thread that I absolutely love how it sounds and it is totally on par with my NC250MP and Topping DM7 combo....
And of course it supersedes my Loxjie A30 by not just a bit

After playing around with my usual DSP plugins I managed to get this response:
View attachment 238977

In the bottom end I apply a 24dB/octave HP filter at 27Hz (not shown above)

Phase looks nice in my opinion:

View attachment 238978

And here is the IMD too:

View attachment 238979

It is pretty nasty around the 100Hz region....

Overall I am very pleased with the sound, I think this project has come to an end - time to look for the next one!

How about an uber flat or compact subwoofer to relieve LF-end of your full-range drivers? That should surely help reduce IMD...

Currently, I am high-passing my dinky little Fostex 6301 at ~180 Hz (pretty high!) so that it can play at close to its max SPL limit while minimizing IMD as much as possible.

Distance as measured at the listening couch is anywhere between 2.8 to 3+ meters:

FDW 15 cycles

According to the manufacturer spec, max SPL is 98 dB at 1 m. At the listening distance of 2.8 to 3 meters at my listening couch with EQ:



The internal 10 watt RMS (max ~20) class D amp clips at just about the point where one would expect.

 

[ppataki]

@fineMen
All the measurements were done at MLP (main listening position) at 75dB, approx. 90cm from the speakers
If you tell me exactly how to perform better/different IMD measurements with REW I would be happy to perform and publish them

@ernestcarl
No sub, I am sticking with 1-way
I am really not bothered by IMD, I am just enjoying the music these babies produce - especially with the new amp; I am blown away

 

[fineMen]

@fineMen
All the measurements were done at MLP (main listening position) at 75dB, approx. 90cm from the speakers
If you tell me exactly how to perform better/different IMD measurements with REW I would be happy to perform and publish them

Try Default Output / Multitone / Dual Tone with an odd relation of the two like 44Hz 1111Hz with levels 4:1 and record the spectrum using the RTA.

I've learned that the driver is of nominal 6 1/2 inch size and claims to cope with 9mm excursion each way, hence has an x-max of 18mm. That would be astounding in deed. So I'm even more eager to understand the actual performance. It would outperform the recent Purify models by far at less than a quarter of athe price.

Only as a hypothesis I would state, that the IM with just +/- 3mm of excursion at, say 40Hz with 900Hz combined will be greater than 10%. Please prove me wrong ;-)

 

[ppataki]

Try Default Output / Multitone / Dual Tone with an odd relation of the two like 44Hz 1111Hz with levels 4:1 and record the spectrum using the RTA.

I've learned that the driver is of nominal 6 1/2 inch size and claims to cope with 9mm excursion each way, hence has an x-max of 18mm. That would be astounding in deed. So I'm even more eager to understand the actual performance. It would outperform the recent Purify models by far at less than a quarter of athe price.

Only as a hypothesis I would state, that the IM with just +/- 3mm of excursion at, say 40Hz with 900Hz combined will be greater than 10%. Please prove me wrong ;-)

OK so here we go: one channel driven at MLP (90cm), the rest you can see on the screenshots

44Hz and 1111Hz

44Hz and 900Hz

 

[fineMen]

OK so here we go: one channel driven at MLP (90cm), the rest you can see on the screenshots

44Hz and 1111Hz

Thank You so much! This clarified the case for me pretty much. The IM is at the right ( less preferable, though ) level of up to 10% with 44 & 900Hz, the base tone's HD shows up expectedly at about 15%. I think at 900Hz the surround has a resonance, also indicated by the impedance graph of Markaudio. The motor isn't as sophisticated as the Purify's is for 4 times the price. I argue that the excursion of +/-3mm wasn't achieved here, more like +/-0,7mm or even less.

Anyway, the driver appears, compared to the available competition, to be quite well designed--interesting!

What You feel about the IM contamination is of course personal. I'm doing the DIY myself for more basic reasons. So I concluded that especially within the range of 250Hz .. 2,5kHz the IM shouldn't exceed 1%, derived from a test of my own hearing regarding perceptibility using headphones. The 1% proved o/k as a limit with finished speakers, listening to music (e/g blues), especially vocals, when comparing particularly low IM designs with more common ones like the ubiquitous ported 6"+1" two-way. But at elevated levels than You seem to need. Nice build!

*ps: the "low IM" design is nothing to write home about, just use more ways, that simple. The contrary paradigm to what You follow. High excursion bass (only 6inch size) up to 200Hz@18dB/oct--(digital DSP)--high bass / low mids up to 600Hz--(passive electric caps, ind/)--mids up to 2,2kHz plus tweeter, all mounted on front into a floor standing enclosure 20cm wide, 30cm deep, 90cm tall, in total equalized flat by DSP.

 

[ppataki]

Very welcome! It is indeed an interesting experiment - I will do the same with my corner line arrays and with my truncated line arrays as well (just to see how they will behave)
I totally understand your point about reducing the IMD by using more ways but I am totally sucked in by the sound of 1-way systems, to me music becomes 'live' - I have heard only a very very few multiway systems that came close to that 'live' presentation
So for the time being I stick to it
btw. my next project will be based on a 15" Fane full-range speaker; probably starting early next year; will publish the results here on ASR

 

[fineMen]

Very welcome! It is indeed an interesting experiment - I will do the same with my corner line arrays and with my truncated line arrays as well (just to see how they will behave)
I totally understand your point about reducing the IMD by using more ways but I am totally sucked in by the sound of 1-way systems, to me music becomes 'live' - I have heard only a very very few multiway systems that came close to that 'live' presentation
So for the time being I stick to it
btw. my next project will be based on a 15" Fane full-range speaker; probably starting early next year; will publish the results here on ASR

Nice! Expermentation brings the reward in DIY. Don't be taken down by some nitpicking perfectionist. Its just another topic to be analyzed.

 

[lewdish]

Anyone try the MarkAudio Tozzi One Kit- Pair ? Seems fairly affordable for a cheap single driver kit that looks fairly stylish. about $80 a speaker Ive always been curious of how they sound and measure.

 

[PatentLawyer]

Anyone try the MarkAudio Tozzi One Kit- Pair ? Seems fairly affordable for a cheap single driver kit that looks fairly stylish. about $80 a speaker Ive always been curious of how they sound and measure.

I have them on my desktop. They have midrange colorations but with DIRAC, they are great on axis.