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View Full Version : DIY ESL build/suggestions THREAD (all questions concerning build will be in here)



thadman
01-30-2007, 03:39 PM
Ok well here it goes, Im making one single thread to hopefully cover all the questions I have I dont have a massive budget, but I do want big sound. ESLs seem like the ticket (not too hard to construct, ill have to buy the parts in bulk so if I screw up I can always make more, easy to experiment on).

I'd like to cover 250/300hz --> inaudibility (I may employ a super tweeter in the future)

I have purchased Roger Sanders book and read the book from cover to cover and have simultaneously searched over here and on diyaudio.com with some success, but still have some specific questions.

What thickness mylar should I use? Roger Sanders recommends 1/2 mil (1/4 mil being ok if you get the high tensile strength stuff), but it seems like a lot of people have had great success with the 3.8 micron mylar offered by ER audio.

Are there any other polyester films that provide greater strength and durability than mylar?

What conductive coating should I use, and the adv/disadv of both? I've heard of graphite and the spray stuff.

What should I use as spacers? Roger Sanders recommends using 1/16" Lexan with epoxy...but warns of putting uneven layers (hes seen 3-17mil glue thickness on the same panel ) which can several inhibit output performance. A few members on diyaudio.com have used urethane tape provided by 3m (foam 1/16"x1/2"x36yd #06453, urethane .045"x1/2"x20yd #06382). Has anybody on here had success with using double sided tape? Is 45 mil to small for 300hz--> reproduction?

What size D/S spacing should I use? I'd like to boost sensitivity as much as possible, to lower the reliance on transformer for output (big supplier of distortion). Im incredibly worried about acoustic coupling of the air...4 high excursion 15s operating dipole next to a 7' x 12-20" diaphragm is quite worrisome.

Whats the best way to tighten the diaphragm? Heat shrink or...use some sort of mechanical tensioning system...

What type of amplifier should I incorporate? huge pro-amp (qsc, behringer) or something along the lines of adcom?

What should I look for in high quality transformers for my intended bandwidth (250/300--->20khz)? Should I consider building my own?

Should I seperate the ESL panel and the array of RS390HFs (ie build the ESL panel and incorporate the RS390HFs in an h-frame)? Should I mount the RS390HFs opposite (ie normal/inverted/normal/inverted) to lower vibrations and non-linear distortion (specifically even order)?

joetama
01-31-2007, 10:19 AM
Give me a little bit to read and digest what you have said there....

Then I will comment....

Beat_Dominator
01-31-2007, 12:41 PM
Heh. Just a suggestion for you. You said "I want big sound".... a short read on various reviews of consumer ESL designs quickly would reveal that ESLs are well known for "not playing very loud, and not very low." But given the dipolar nature the stage can be big... so it depends on what you meant by "big sound".

Secondly, the cost/benefit ratio on a DIY ESL is horrendous. With the required materials and expensive transformers required to get the 3000+ volt stator charge are hardly worth it. Then you have to contend with the stator materials and the inevitable arching you'll get at high output levels.....which will burn hols in the mylar.

If I wanted something ESL-like in a DIY project I wouldpersonally look at a dipole line array of some sort.

Just my 2 cents :)

If you decide to go ahead with ESLs, good luck.... you are a brave soul!

joetama
01-31-2007, 12:41 PM
OK, are you using the RS390HFs for subwoofers or are you using them for everything below 300Hz? Also, I would mount them all front firing because that is how the cone is designed to produce a specific pattern. The driver and basket will cause the pattern to change which would disrupt the coherence and coupling of the low frequency drivers.

Also, what are you output specs on the ESL you are using/building. Some of them are able to output audio down to 300Hz but suffer greatly from doing it. I have read/heard it is best on a lot of film transducers to only go to 500 Hz or there abouts even if they are rated much lower.

Also, with the subs you have selected you might have issues with cone breakup and efficiency at 300Hz. I am thinking you are planning on using them in an array format, however I think you are going to be pushing the drivers well out of their sweetspots which could cause beaming and distortion. If you are planning on using these as you “low-mids” and lows you should probably put them in the array next to the higher frequency transducer. This way you get the coupling and source continuity for good imaging and blending.

I'm guessing you are also using a dipole design to boost the response from the baffle harmonics. I would say this is fine in low midrange but I don't know how it would perform well with the subwoofers you have selected. Seems to me that the baffle length would have to be larger than practical, with out running the numbers to find out.

As to the construction issues, I am sure not a lot of people have much experience with this. I have read up on it years ago trying to figure how to do it. Honestly, I would use Sanders recommendations and then experiment from there. Is there a big difference in weight and price from the mill to the mill stuff? If the mill stuff is lighter it seems that you would have a better high end because of the lack of mass. However, this might impact the low end performance because of its inability to move air.

Spreading the epoxy could be a very tedious process, and the urethane tape seems easier. Since you have to order in bulk maybe you could try both methods… I think that the 45 mill double sided tape wouldn’t be the best method. (And that is just a guess I could be wrong.)

Amp, you probably can’t go wrong with a QSC Amplifier. They are very clean, very reliable, and not picky to what type of load they are running on.

joetama
01-31-2007, 12:42 PM
Heh. Just a suggestion for you. You said "I want big sound".... a short read on various reviews of consumer ESL designs quickly would reveal that ESLs are well known for "not playing very loud, and not very low." But given the dipolar nature the stage can be big... so it depends on what you meant by "big sound".

Secondly, the cost/benefit ratio on a DIY ESL is horrendous. With the required materials and expensive transformers required to get the 3000+ volt stator charge are hardly worth it. Then you have to contend with the stator materials and the inevitable arching you'll get at high output levels.....which will burn hols in the mylar.

If I wanted something ESL-like in a DIY project I wouldpersonally look at a dipole line array of some sort.

Just my 2 cents :)

If you decide to go ahead with ESLs, good luck.... you are a brave soul!

Indeed.....

bdawson72
01-31-2007, 12:46 PM
This may be slightly over my head

skeptikal
01-31-2007, 12:48 PM
Let me know if you need help building it!

joetama
01-31-2007, 12:49 PM
Also, FT Wayne is only about an hour away from where my home town is....

So, if you get this constructed I am very interested in hearing it......

thylantyr
01-31-2007, 01:03 PM
I told thadman in private, not to reveal his ESL build in public domain, but he
already posted it on at least two forums. Reason. If he comes close to his
design goals, this ESL design would kill every ESL commercially available and
why reveal the 'recipe' in public doman when you can use it for other things.

joetama
01-31-2007, 01:10 PM
I told thadman in private, not to reveal his ESL build in public domain, but he
already posted it on at least two forums. Reason. If he comes close to his
design goals, this ESL design would kill every ESL commercially available and
why reveal the 'recipe' in public doman when you can use it for other things.

Well unless he is looking to make money on it then why not tell people about it so they can do it themselves? :eyebrow:

thylantyr
01-31-2007, 01:11 PM
Well unless he is looking to make money on it then why not tell people about it so they can do it themselves? :eyebrow:

He did tell me, in private. lol
People interested can always ask, in private. lol

I stopped broadcasting uber ideas in public domain a few years ago... because
doing a simple google search revealed the cool ideas.... Later someone
stakes claim on those ideas when they didn't come up with it. lol

joetama
01-31-2007, 01:19 PM
He did tell me, in private. lol
People interested can always ask, in private. lol

I stopped broadcasting uber ideas in public domain a few years ago... because
doing a simple google search revealed the cool ideas.... Later someone
stakes claim on those ideas when they didn't come up with it. lol

True I hate it when people steal my ideas....

But, if his design comes out that good then he should patent it!!!


Then sue the pants off someone if they take his idea for their own!

thylantyr
01-31-2007, 01:31 PM
I think the issue is taking the already existing ESL design that has been
invented by the dinosaurs and just making it beefy. I don't know if the
'beefy' part is patentable because the concept is the same.

joetama
01-31-2007, 01:46 PM
I think the issue is taking the already existing ESL design that has been
invented by the dinosaurs and just making it beefy. I don't know if the
'beefy' part is patentable because the concept is the same.

But, the thing is not every combination of 'beefy' will make it better or worse. You patent the exact concept and mix that you have down that works.

The loudspeaker was patented a long time ago, but certain loudspeaker technologies still get patents...

thylantyr
01-31-2007, 01:52 PM
Score;

This forum, this thread: 14 replies

HTguide thread: 0 replies
http://www.htguide.com/forum/showthread.php4?t=24523

We are winning. lol

joetama
01-31-2007, 02:05 PM
HT Guide has one now.....

thadman
01-31-2007, 02:32 PM
The reason ESLs usually lack output is because they are asked to provide displacement over an extremely wide range...which it cannot support.

Im planning on using a 7' panel by 16 or so inches wide. If I used a stator spacing of .07"(70mil), I wouldnt be able to use the urethane tape. Keeping the 100:1 stator ratio intact, I would have a maximum of 7" so 2 sections. If I had 2 7" sections, I could expect 1/4" of inactive area of each side of the spacer so I lose 1" of effective radiating area. I am down to 13(2.54) by 84(2.54). This is equivalent to 7045cm^2 with 1.778mm of allowed excursion before contacting the diaphragm... I have to decide whether I will couple it to the RS390HF baffle, but either way the ESL will be placed on a 24"+ baffle. I will get a 3dB+ boost around 283hz...so the dipole effect in actuality will be doubling my displacement down low. I will not be limited by displacement down low by a longshot...although I may have issues with the resonance of the diaphragm if I want to cross at 150hz.

thadman
01-31-2007, 02:34 PM
I need a material that has higher tensile strength (greater surface tension is linear with output) and lower weight than 3.8um mylar...that also has the ability to hold a static charge and has an extremely high resistance.

Any options?

thadman
01-31-2007, 04:15 PM
Also if im aiming for a 250hz crossover point to prevent comb filtering the drivers need to have a 1/2 wavelength CTC spacing. I am required to use 1/2 wavelength because I will be listening in the nearfield since it is setup as a linesource. You simply double the frequency to get half the original wavelength (500hz) and then divide the frequency by the speed of sound in inches (rounded to 13397). 13397/500=26.794", the centers of each driver can be no more than ~27" apart. The drivers will exhibit no beaming as they will be spaced closer than 1/2 wavelength of the xover frequency.

The RS390HF also have extremely low inductance (1.0mH if I recall) and a crazy resonance peak right around 1600-1800hz (the peak starts to slope slowly form right around 1.2khz and then things start to get nasty around 1.5khz). The third harmonic of this peak (assuming 1600hz) is 533hz and distortion will start to rise >400hz. I will be crossing nearly an octave below this, so non-linear distortion should be no issue.

Also heres a review of the HF series http://www.mfk-projects.com/rs_12_hi-fi.htm
quoted from the review

Anyway, one amazing thing about this woofer is its ability to perform well up to several hundred Hz. This is a little unusual for this kind of heavy high excursion driver. I guess if you are not too critical you could use this driver to 1Khz but personally I wouldn't use any 12" driver that high except in certain pro-audio applications. I would feel very comfortable however using this driver to 300 Hz. In most of the applications I have planned for it I will not use it above about 140 Hz but that is more because this is what the application calls for rather than any concern with using this driver higher in frequency.

I think this driver will be a first rate performer in both di-pole applications and box applications. It seems about as good as the XLS in the mid bass region with some frequencies possibly better on the XLS and others better with the RS. Generally the two are close in the mid bass region. The RS is better at very low frequency and will also be better than the XLS at frequencies above 100 Hz. The RS is also the quieter of the two making it a much better choice for any dipole application than the XLS.

1loudsuv
02-14-2007, 03:45 AM
confusing

joetama
02-14-2007, 12:40 PM
confusing

I here there is a little of that going around these days... :fyi:

joetama
04-09-2007, 09:51 PM
You ever build these?

1loudsuv
04-10-2007, 03:37 AM
I here there is a little of that going around these days... :fyi:

i know one thing i aint confused about. room treatment! it rocks i just finished listining to a cd after installing in my towers (1" foam) and on my walls and that made hella ofa good difference in sound quality. remember what they say your not hearing your speakers your hearing your room.


sorry to the op for the thread jack but that day i posted "confused" i was spamming. as i know nothing about crossovers.

thylantyr
05-01-2007, 02:59 PM
I guess he doesn't love this forum no more......... lol


http://www.htguide.com/forum/showthread.php4?t=25746

joetama
05-01-2007, 04:13 PM
Apparently not.... Oh well...