Hello forum members,
I am new to this forum, but I already have quite some experience in building speaker boxes.
I now have three rooms to be equipped with 5.1 home cinema speakers, although the main "payload" is gonna be music.
Because of high cost associated with I decided to build the speakers myself. I need the speaker boxes to be universal enough to accommodate a few different drivers.
My choice for cabinets is: Troels Gravesen Ekta TL http://www.troelsgravesen.dk/Ekta-TL.htm for front speakers and
STUDIO-101-mkII http://www.troelsgravesen.dk/STUDIO-101-mkII.htm for rear speakers.
But I wanna make it clear that this is just a guidance for the construction/shape/size of the speaker boxes. It is not my intention to copy those designs.
So what do I want to make?
I like those designs of Troels, but the speaker drivers he uses are way out of my budget. So I am looking for cheap replacements.
But I like the concept of the boxes. His Ekta TL can be adopted as bass-reflex, TL can be shorten or extended easily.
So, I need a your suggestion of what cheaper drivers can be used in those cabinets. I can make some adjustments to the cabinets to accommodate other types of drivers. No problem. But I want the genera concept to remain the same. TL for the front speakers and BR for rear speakers, full bandwidth for both.
So for Ekta TL my initial choice is:
-SB20PFCR30-8, https://sbacoustics.com/product/8-sb20pfcr30-8-paper/ , the same fs as the speaker in original design, so no mods to the cabinet are necessary,
- mid range?
-DT-300 from Monacor, https://www.monacor.com/products/akcesoria--/glosniki--/glosniki-wysokotonowe-hifi-/dt-300/
For STUDIO-101-mkII:
I consider those two speakers as good enough quality for the money, and good enough for me. In Europe all those drivers are available for more or less 50 Euro. And I would set the budget for the speakers in that range, plus minus a few euros. I already build some speakers with SB20PFCR30-8 and I consider it a very good driver for the price. Very good. But I am open for suggestions here.
The requirements are (for both front and rear):
Can you suggest some good budgetary drivers that have good sensitivity and can fit in the cabinets mentioned?
As I said, the Troels designs are given just to give you some idea of what I want to build.
I still need an idea for a central speaker. I want it also to be full bandwidth with 8" woofers.
I am new to this forum, but I already have quite some experience in building speaker boxes.
I now have three rooms to be equipped with 5.1 home cinema speakers, although the main "payload" is gonna be music.
Because of high cost associated with I decided to build the speakers myself. I need the speaker boxes to be universal enough to accommodate a few different drivers.
My choice for cabinets is: Troels Gravesen Ekta TL http://www.troelsgravesen.dk/Ekta-TL.htm for front speakers and
STUDIO-101-mkII http://www.troelsgravesen.dk/STUDIO-101-mkII.htm for rear speakers.
But I wanna make it clear that this is just a guidance for the construction/shape/size of the speaker boxes. It is not my intention to copy those designs.
So what do I want to make?
I like those designs of Troels, but the speaker drivers he uses are way out of my budget. So I am looking for cheap replacements.
But I like the concept of the boxes. His Ekta TL can be adopted as bass-reflex, TL can be shorten or extended easily.
So, I need a your suggestion of what cheaper drivers can be used in those cabinets. I can make some adjustments to the cabinets to accommodate other types of drivers. No problem. But I want the genera concept to remain the same. TL for the front speakers and BR for rear speakers, full bandwidth for both.
So for Ekta TL my initial choice is:
-SB20PFCR30-8, https://sbacoustics.com/product/8-sb20pfcr30-8-paper/ , the same fs as the speaker in original design, so no mods to the cabinet are necessary,
- mid range?
-DT-300 from Monacor, https://www.monacor.com/products/akcesoria--/glosniki--/glosniki-wysokotonowe-hifi-/dt-300/
For STUDIO-101-mkII:
- sub-mid range ?
- DT-300 from Monacor
I consider those two speakers as good enough quality for the money, and good enough for me. In Europe all those drivers are available for more or less 50 Euro. And I would set the budget for the speakers in that range, plus minus a few euros. I already build some speakers with SB20PFCR30-8 and I consider it a very good driver for the price. Very good. But I am open for suggestions here.
The requirements are (for both front and rear):
- absolute minimum driver sensitivity 90 dB (no compromise on that),
- bass as low as possible,
- the size and volume of Ekta TL are just about right for me, but I can adopt it a bit for the driver
- rear box volume can be up to about about 30 litres, 2-way, sensitivity min 90 dB, good bass.
Can you suggest some good budgetary drivers that have good sensitivity and can fit in the cabinets mentioned?
As I said, the Troels designs are given just to give you some idea of what I want to build.
I still need an idea for a central speaker. I want it also to be full bandwidth with 8" woofers.
If you are on a right budget, would it not be better to consider a two way cabinet design? The Ekta TL may not be the best choice for your implementation (cabinet set up for three way configuration and transmission lines need to be recalculated if you are changing from a 6.5" to 8" driver with different T/S parameters). There are some of his older designs that are worth checking out where you get access to all of the crossover details and can find some of the drivers second hand if budget is a concern. One thing I would say, is that the tweeter in the Ekta Mk2 is worth the money.
These use budget SB Acoustics drivers and look really nice:
http://www.troelsgravesen.dk/SBA-861-PFCR.htm
Geoff
http://www.troelsgravesen.dk/SBA-861-PFCR.htm
Geoff
I would rather avoid Troles' designs with TL enclosures. In my opinion, they are not well designed.
It is not my intention to copy Troels' design. And I do realize that changing the driver requires a new xo and enclosure tweak. This is all fine with me.
Some would say I am on a budget but I would say I try to be reasonable with what I spend on speakers. I have three sets of 5.1 home cinema to build. I would go bunkrupt if I spend $500 on each driver.
I decided that the fron speakers would be: 3-way, TL, 8" bass driver. And I develop the rest based on this starting point.
@mV8 Why is it not well designed? I simulated Ekta-TL using Hornresp. It all checks out quite well. There are things that I would do differently, but I do not see major issues with his designs. Everyone of us would want make some changes. The simulation also confirms that SB20PFCR30-8 will work in this enclosure as well. Even without any major changes. I like the concept of this enclosure. The way the mid compartment shares the space with internal TL, easy to modify, easy to build.
Are there any other 2-3 way TL designs worth having look at? Not too large enclosure, simple to build. It doesn't have to be a design that matches my requirements in 100%.
Any other 8" budget drivers worth considering?
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If so, that says you are competent to design a new xover and box for your selected units. Then why do you need advice from us?
Go for it!
I have begain my diy journey with a 3 way, then a 4 way with 2 drivers in 16-20 ohm, and 2 drivers in 8 ohm, and it end up like " a miljon buck" speakers.
Trial and errors make you learn the most!
If the speaker is suitable for a BR enclosure, it will also work in a TL enclosure.
I have not seen any simulation for Troels' TL design. A person experienced in TL design will immediately see that the tunnels are too long, the amount of damping and its type is far suboptimal. Taper tunnels can definitely be better optimized in terms of damping harmonic resonances, as well as the length of the tunnel itself-this is not evident in Troels' design.
In my opinion, these designs are simply not well optimized, done rather on the basis of old recommendations, which were not based on computer simulations, but some golden rules from several thousand years ago 😉
Interesting.
I have the Ekta-TL in my living room.
Would you mind to share what the problems might be. Im very curious, and who knows, i might make a new speaker based on your suggestions.
@mV8 AS I said, I simulated Ekta-TL in Hornresp. It checks out. It is optimal. Within the limits to which I can reproduce the design I do not know exactly the density of dumping material, but we do not have to be gram accurate here to be able to tell that it is definitely not wrong.
In fact I am pretty impressed how low can SS go with the frequency. Somewhere in the middle is Wavecor WF223BD02 but a bit dissapointing considering the price. SB acoustics is the worst here and I am a bit dissapointed that it does not even come close to SS. All these drivers are good for bassreflex, have very very very similar T-Sm parameters, but perform very differently.
I mnetion Ekta-TL just to paint the picture of what my plan is.
This is right to some extend only. Both, the original SS 18WU/4741T00 nad SB20PFCR30-8 are designed for BR enclosure, but the SS goes much lower with f3dB in Ekta-TL than SB20PFCR30. At the cost of sensitivity.
In fact I am pretty impressed how low can SS go with the frequency. Somewhere in the middle is Wavecor WF223BD02 but a bit dissapointing considering the price. SB acoustics is the worst here and I am a bit dissapointed that it does not even come close to SS. All these drivers are good for bassreflex, have very very very similar T-Sm parameters, but perform very differently.
@kgrlee I am looking for inspiration! And I want an advise as to what drivers are suitable for this type of design. There is many drivers out there. I cannot possibly simulate each one of them. So if anyone here has experience with building TLs and can suggest an 8" driver with good low frequency extension and reasonable good sensitivity (I am looking for at least 90dB) I would be greatfull.
I mnetion Ekta-TL just to paint the picture of what my plan is.
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Hornresp's damping simulation is far from reality.
If the volume for BR and TL is the same, and the tuning frequency is also the same, then the frequency response will also be virtually the same. The TL as well as the BR is a 4th order resonator.
Hi,
Just to my curiosity, why do you set minimum sensitivity to be absolute at least 90dB if this is for residential use?
I use 86dB SPL woofers, which is what I can source locally, and I have excellent results.
Examples of what I built: 3-way speakers FR 26Hz @-3dB (big ones 80 liters) and FR 30Hz @-3dB (small ones 39 liters).
There is no need for subwoofers - just 2 stereo loudspeakers.
The difference is just 4dB (2.5 x power in Watts).
"just" 4dB 🙂 It is irrational to pump hundreds of watts into speakers in a living room
I just think good sensitivity speaker sound better. 90dB is about right. More is worse, less is also worse. Just my opinion.
The first simulation is the SS 18WWU4741T00, the bottom one is SB20PFCR30-8. They both work in the same enclosure, although SB-A does not go as low with the frequency response. Anyway, I do not see any problems with Ekta-TL design.
Profile says you are in Poland.
Have you checked stx? Those driver are very economical compared to most you will find, and some have a very good 'feature' set for the price, like alu. demodulation rings, copper shoring rings, etc.
https://stx.pl/
Also worth to check :
https://www.traumboxen.de/ad-audio/index.htm
A&D makes solid drivers, they are just fully made in China, but properly tested, Klippel verified etc.
Can't promise the specs suits you, they also have other models, you might have to inquire.
Does not have to be worse then buying every part in China and assembling them somewhere else, those methods is what 90% of the audio industry does anyway.
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You mentioned hundreds of watts if using 86dB SPL, but what SPL do you plan to have in your room?
How far do you listen from your speakers?
With 100W and 86dB sensitivity you get:
106dB SPL at 1m
100dB SPL at 2m (-6dB aprox.)
I just want to understand your requirements, since I'm planning to build speakers for other people (studios and residences), not for my own use.
It's difficult to find a good woofer with reasonable size (8" or 10") that goes flat below 30Hz with high sensitivity.
In my case, its cheaper to invest in amplifier than on imported woofers, since I live far from developed countries (tax and freight are very high).
How far do you listen from your speakers?
With 100W and 86dB sensitivity you get:
106dB SPL at 1m
100dB SPL at 2m (-6dB aprox.)
I just want to understand your requirements, since I'm planning to build speakers for other people (studios and residences), not for my own use.
It's difficult to find a good woofer with reasonable size (8" or 10") that goes flat below 30Hz with high sensitivity.
In my case, its cheaper to invest in amplifier than on imported woofers, since I live far from developed countries (tax and freight are very high).
I don't know if the Mivoc XAW HC series fiberglass honeycomb drivers are still available from Germany. Inexpensive and (ought to be) perfect for tapered TL.
https://loudmagnet.com/html/mivoc.htm
Indirectly, they jump-started my diy journey. Someone on hifidiy.net (China) had raved about the 8" driver. I couldn't find Mivoc, but the same membrane material was used by Eve Audio (spun-off from Adam); Eton MAS; Jamo C series; and a Chinese brand AVLight (multi K$ TOTL) whose 4" and 8" tone-sweeps sounded just like the Mivoc response charts looked. They were made into "LXmidi" XO-less folded concentric TL. Eve 5" driver was series-1st-order crossed with 1x2in AMT in 7L tapered TL called "HeilEve", my first diy.
https://loudmagnet.com/html/mivoc.htm
Indirectly, they jump-started my diy journey. Someone on hifidiy.net (China) had raved about the 8" driver. I couldn't find Mivoc, but the same membrane material was used by Eve Audio (spun-off from Adam); Eton MAS; Jamo C series; and a Chinese brand AVLight (multi K$ TOTL) whose 4" and 8" tone-sweeps sounded just like the Mivoc response charts looked. They were made into "LXmidi" XO-less folded concentric TL. Eve 5" driver was series-1st-order crossed with 1x2in AMT in 7L tapered TL called "HeilEve", my first diy.
I see a huge problem with harmonic resonances, which will affect the frequency response of the speaker. This can be ignored in subwoofers, but not in 3 and 2 way systems.
mV8 said:
So i should be able to fix that.
If it is in the frequency response i should also be able to measure the difference before and after.
Any tips on how to measure and what i should be looking for? (before i get started running in the potentially wrong direction).
Also, what, if anything should i do to fix it? New absorption material i think you mentioned?
Thanks in advance
Klaus
Attachments
I'm afraid there's not much you can do with an enclosure whose tunnel geometry is not optimally designed. Of course, you can add damping, in order to minimize resonances, but this will simultaneously weaken the radiation of the quarter-wave resonance. Besides, the design of the tunnel itself in general already does not allow for much change in its damping.
Troels does not show a measurement of the tunnel response in his designs. If you are curious to see what it looks like, along with its harmonic resonances, you can make a measurement of the tunnel in the near field. Place a measurement microphone at the very beginning of the tunnel output and take a frequency measurement.