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Ekta Mk2? Beyond the Epos ES 22s
Ekta Mk2? Beyond the Epos ES 22s
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Old 6th November 2017, 05:50 PM   #1
lupo 1 is offline lupo 1  Italy
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Default Ekta Mk2? Beyond the Epos ES 22s

Hi fanatics,
Having read and enjoyed a portion of the epic Giuseppe D'Appolito MTM 'Thor' thread, I hesitated more than once before registering, and hesitated again before posting this thread. My knowledge of Audio Physics extends to how to put 30 yr. old Naim connectors into their respective sockets - but I can make cabinets.
Can anyone reassure me that if I set out on an Ekta Mk11 build, there's a good chance that they will please me as much as, if not more than, my 30 yr old Epos es 22s? Are they an appropriate choice for my current amplification? i note that the DTQWTs can be built for a similar cost, but maybe they're less of a match to my system.

Naim 72 pre with Avondale Audio Audiophile 831 mod.
Avondale upgraded Hi Cap P.S.
Graham Slee Reflex M phono
Avondale Audio s100 80W(+/-)
Graham Slee Spatia speaker cables

Last edited by lupo 1; 7th November 2017 at 04:14 AM.
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Old 7th November 2017, 05:21 AM   #2
LineSource is offline LineSource  United States
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From the datasheet, the design philosophy behind your Epos ES22 speakers seems "odd" by today's design knowledge.
1) The tweeter uses only 1-capacitor for the crossover, and the tweeter is located several inches above the midrange on the front baffle such that lobbing will occur.
2) The 6" poly-plastic cone midrange is run full range with no crossover components.
3) The 6" poly-plastic cone woofer uses a single inductor for the crossover.
I would not expect "audiophile grade" sound from this design.

The EKTA II uses some of the absolute best drivers in production, with time and phase adjusted crossovers. (Drivers: 7" woofer 18WU/4741T00 4" midrange 12MU/8731T00 1" dome tweeter D2608/913000) The drivers use slit-paper cones to reduce resonances. Very low Le motors for wide&flat bandwidth. Open chassis frames to allow clean unobstructed air flow. The 4" midrange 12MU/8731T00 has proven to deliver great detail with a very natural tone. The 7" woofer 18WU/4741T00 will produce CLEAN, CLEAN, CLEAN bass with -F3 = 40Hz before room gain. Properly constructed, I would expect "audiophile grade" sound from this design.

If you desire more powerful mids and deeper bass, Troels SB10 design uses a larger cabinet to hold a 5.5" midrange and 10" woofer( SB29NRX75-6 delivers -F3=28Hz in ported 55l volume). How large is your room? There are a few other SB-Acoustics Satori MR13P and MR16P midrange drivers based free diy designs with excellent sound reasonable prices.

SBAcoustics 10
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Old 7th November 2017, 09:14 AM   #3
lupo 1 is offline lupo 1  Italy
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Hi Line Source

Really good of you to get back and for being so informative. I'm very reassured! Yes, Robin Marshall claimed it was all about the design of the drivers, but that was then ... and your summing up of his design made me chuckle.

Sounds like I should just get on with it then, but FWIW my room is almost square, unfortunately, about 5 x 5 metres and 2.7m to a heavily beamed ceiling. It does have quite wide doors (one set between the speakers) that are invariably open at both ends. No problem to have speakers up to 60cm away from front wall and well away from the corners as well.

There's an earlier, very positive mention of the SBA 10, albeit the member was critical of some aspects of other TG designs.
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Old 7th November 2017, 06:20 PM   #4
lupo 1 is offline lupo 1  Italy
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...I meant to add that, re your reference to other diy MR Satori based designs, these would have to include cabinet design for me to be able to work with them. I've noticed that Selah Audio do an interesting 1,700 dollar Satori kit called the "Essenza" with dual 7.5" woofers a 5" mid and Be tweeter - seems a lot of drivers for the money. Price wise this is not so far off the Ekta, but the Selah website doesn't compare with the wonderfully transparent and informative TG site - there's nothing about crossover/cabinet design etc. that might indicate this design's particular virtues - musicality, delicacy and detail more important to me than how loud they go...

Last edited by lupo 1; 7th November 2017 at 06:32 PM. Reason: got a figure wrong
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Old 8th November 2017, 09:40 AM   #5
giralfino is offline giralfino  Italy
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Quote:
musicality, delicacy and detail
This is highly subjective, you can't buy a speaker based on a write up. If you need to audition before buying, you need to opt for commercial offerings. I still think that the used market offers real savings and permits to resell without (significant) loss.

Having said that a kit from some competent designer using good value drivers should not disappoint. In this respect IMHO I find the old TG designs a good source of inspiration but think that a more competent designer could have done better on some of them. Moreover recently he found the holy grail in the LR2 slopes with stepped baffle. He is doing a redesign of old speakers with the stepped baffle approach and those new designs aren't open anymore, you have to buy a kit. And I don't ever want to talk about his choice of crossover components.

If I were to buy a kit with the Satori drivers, I'd buy the Kairos, it can even be modified to a 3-way if you need to (see here: https://app.box.com/s/a4bqr447s7ox7v9kt7r9tjui0h7yqkrv).
If you feel that a 10" driver is too much for your room (25sqm isn't a big room), and a 8" woofer would be better I think that the TG 3w-classic is a good value speaker: SEAS-3-Way-Classic

Ralf

If you buy a kit there should be a detailed plan for the cabinets, sometimes you will have it before buying, but I wouldn't build anything without the drivers in hand (it's all about tolerances, if you route a rebate too small or big, it is a pain to correct it).
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Old 8th November 2017, 10:25 AM   #6
lupo 1 is offline lupo 1  Italy
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Quote:
Originally Posted by giralfino View Post
Having said that a kit from some competent designer using good value drivers should not disappoint. In this respect IMHO I find the old TG designs a good source of inspiration.
Thanks for such a perceptive and very helpful response re the TG kits and some alternatives. The issue for me is my cabinet making skills far exceed my knowledge of electronics, not to mention audio physics, so a kit, closed or otherwise (I'm bitten by this bug) it will probably have to be.

Are you saying that the stepped baffle, in the case of the TG Ekta, is sonically a step backwards from the earlier model, or is your point more to do with a move a way from designs that can be adapted, explored, modified? From my point of view, the stepped baffle poses a bit of an aesthetic challenge - it's a bit harder to get the speakers looking good compared to a flat baffle. However, I'm also very interested in your critical comments about this and the "holy grail of LR2", but maybe it's above my head - a steep learning curve (or is it slope?)

Anyway, I'm hanging on to your main point re competent designers and decent drive units and thanks for all of your excellent advice and suggestions!
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Old 8th November 2017, 01:23 PM   #7
giralfino is offline giralfino  Italy
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The problem is that the Ekta mkII has nothing in common to the original Ekta, so comparing them is pointless, it seems only a marketing thing in order to buy the whole kit for which obviously TG receives a fee. I don't have a problem with this, but you can't even find the original design in the TG site, even if it is there, you have to use google, and that disturbs me.

What I don't like in the TG stepped baffle approach, is that I don't see any word on how to address the obvious diffraction problem that the step has.

To your original question, I wouldn't worry about speaker-amp match, as a decent solid state amp should drive every speaker. I would worry about a speaker-room match, and I think that the DTQWT is way too big for yours.

Ralf
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Old 8th November 2017, 02:04 PM   #8
lupo 1 is offline lupo 1  Italy
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Default What I don't like in the TG stepped baffle approach...

Okay, the diffraction issue is a really helpful pointer for me to pursue, perhaps with TG himself. Really helpful point about the DTQWT as well - that's one less bit of thinking to do - thanks!

Paul

PS I've just found an article by TG that appears to have addressed the issue, satisfactorily? Unfortunately, the URL gets a 401 when I type it, so I can't send you the link. I just googled Troels Gravesen stepped baffle diffraction issues

Last edited by lupo 1; 8th November 2017 at 02:33 PM. Reason: extra info
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Old 9th November 2017, 04:15 PM   #9
lupo 1 is offline lupo 1  Italy
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Default tweeter located several inches from the mid range and lobing will occur

- probably not of interest, but re comments by LineSource on the old Epos and lobing, the distance between the Epos tweeter and mid centres is only 10 mm more than that of the Ekta Mk11 tweeter and mid.
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Old 9th November 2017, 05:59 PM   #10
system7 is offline system7  United Kingdom
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lupo 1, you are right. We ARE fanatics. Here is your ES22 (below) for reference.

Epos is a tremendously interesting company. Now owned by Michael Creek rather than Robin Marshall.

I'm not sure I actually agree with Robin Marshall on everything, but I listen to his ideas. What he did tremendously well, was build well-behaved polycone bass units that needed little filtering to work well. One of my earliest speakers was the Mordaunt Short MS10i, which bore a close resemblance to this Epos ELS-3 design.

I think you can see the pedigree. Robin tended to use very simplistic filters, as in the famous two way Epos M12i. A mere 2.2uF capacitor plus a slightly mysterious 47R resistor on the tweeter.

As it goes, Michael Creek tends to use more complex, steeper filters these days with the same well-behaved drive units. Which to me, means they go louder with less distortion.

All a trade-off. Who knows who is right?

But, as a hobbyist, I think I could have great fun giving your ES22 a more complex filter. They are too good to throw away.
Attached Images
File Type: jpg Epos ES22 speaker.JPG (25.9 KB, 287 views)
File Type: jpg Epos M12i Crossover.JPG (49.9 KB, 285 views)
File Type: jpg Epos_ELS-3_Loudspeaker.JPG (23.6 KB, 279 views)
File Type: jpg Epos ELS-3 Crossover.JPG (15.8 KB, 285 views)
File Type: jpg Epos_ELS-3_Crossover.JPG (19.9 KB, 283 views)
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