Passive crossover for ESL's

[dochungwell]

It seems that the consensus would agree that ESL's are best when bi-amped and to utilize an to utilize an active crossover however, Does anyone on this forum use or has experimented with a passive crossover to cut the low frequencies so as a mid/sub can be utilized.

Could a standard passive crossover be sufficient to perform this task?

[CharlieM]

Originally Posted by dochungwell

It seems that the consensus would agree that ESL's are best when bi-amped and to utilize an to utilize an active crossover however, Does anyone on this forum use or has experimented with a passive crossover to cut the low frequencies so as a mid/sub can be utilized.

Could a standard passive crossover be sufficient to perform this task?

Active bi-amp is the best choice but given the cost of a second amp and active crossover, a passive crossover sounds appealing. I wouldn't know how to design one for an ESL myself. Some have done it, though-- I believe "Calvin" posted some info on the subject so you might try searching his posts and see what comes up. There are tons of freebie crossover calculators on the web but all of them I've seen are useless for ESL's because they model the driver impedances as resistance; whereas an ESL panel is a big capacitor that pushes back on the amp. You might also contact Russ at the "Just Real Music" website, as Russ uses passives in his hybrid ESL's and even shows some schematics on his website.

[bolserst]

Originally Posted by dochungwell

It seems that the consensus would agree that ESL's are best when bi-amped and to utilize an to utilize an active crossover however, Does anyone on this forum use or has experimented with a passive crossover to cut the low frequencies so as a mid/sub can be utilized.
Could a standard passive crossover be sufficient to perform this task?

It is not that difficult to design a passive crossover to effectively EQ the response flat, notch out the diaphragm resonance, and properly filter out the low frequencies to cross over to a dynamic woofer. But, I will add that it is nearly impossible to get a properly working passive crossover for a hybrid ESL without proper measuring equipment. The widely varying ESL impedance has a pronounced and sometimes unpredictable effect on the response of the crossover/ESL combination.

Four or five years ago, Calvin had some posts on how to create proper passive crossovers for ESL hybrids. It is more of an example rather than a complete how to, but will give you an idea what is involved. It includes how to swamp or linearize the drastically changing ESL impedance before the crossover, and notching out the diaphragm resonance. Personally, I prefer to damp the diaphragm resonance with resistive flow damping of silk screen mesh. But, I understand the desire of some to keep their ESL panel optically clear.
Here is the thread:
Ping Calvin

If you have the equipment to measure response and impedance there are certainly a few folks here that can walk you thru the process.

You might consider a passive crossover as secondary goal, once you get an actively crossed over ESL hybrid up and running.

[dochungwell]

Hello Charlie/Bolsert,

Thanks for your suggestions. I looked in on Russ's site and he does utilize passive crossovers, and Calvin did post two passive crossover schematics. Ultimately I just wanted to consider all possibilities prior to buying ultimately 5 amps and and 2 active crossovers.... I dont want my next forum to be...recently divorced men with kick-*** sound systems.

One the panels are completed I will provide both sound measurements and capacitance of both panels.

I should have panels working tonight....Hopefully!

[CharlieM]

Originally Posted by dochungwell

Hello Charlie/Bolsert,

Thanks for your suggestions. I looked in on Russ's site and he does utilize passive crossovers, and Calvin did post two passive crossover schematics. Ultimately I just wanted to consider all possibilities prior to buying ultimately 5 amps and and 2 active crossovers.... I dont want my next forum to be...recently divorced men with kick-*** sound systems.

One the panels are completed I will provide both sound measurements and capacitance of both panels.

I should have panels working tonight....Hopefully!

Five amps and two crossovers to drive two hybrid speakers? Are you using mono-block amps? I use a single three-way stereo crossover feeding two hybrid ESL's and a pair of mono subs. You could probably pick up an adjustable active crossover for cheap on Ebay ($75 or less, I would think)

[geraldfryjr]

If you are familar with building opamp circiuts you can cobble an active crossover together rather cheaply once you get some measurements done on your system.

And If you have a few NP caps laying around they can get you by as well as they did for me when I frist fired up my panel I had used an old Marantz crossover from an SP-200 and got it to work okay but not perfect.
It work good for A first try until I figured out exactly wht the transformation ratios and amplifier reqiurements were needed.

It turned out that the 8" sub was much louder and had to pad it down alot to get them balanced.
But may I remind you that I am talking about a very small panel and I later found that 2 or 3 were required to match the output of my little 5 1/4" sony woofers (About 1 sq ft of area for the esl) as well as a very high transformation (about 1:400).

You will not need that high of transformation ratio with larger panels.

This is where it become a juggling match of transformation ratio and low frequency core saturation until I finaly got something that worked well.

This is where a large core is beneficial.

I biamped using only my mixer EQs as a crossover,But it worked for the time being and sounded Incredibly Awesome!

It was a great learning experience but it would have been much easier had I have had a variable active crossover and proper amplifiers at the time to find the exact matching frequency for the crossover.

If you are just starting over from scratch you can easliy have as much invested in parts as a premade active ones are only aabout $99 to $150 for an analog type and they are variable not to mention the time involved in building one and getting it tuned in per application.

If you have acsess to just use one for a while then you could find your points that way too build one.

Another way that some are going about it is to use the computer as a crossover or too split the left and right tracks into two seperate bass and treble tracks providing you have a 4-channel 24bit output card.

I believe there is some software out there that does this with a common suround sound output card as I have looked into this but needs to be researched more.

But I know this does exisist and would be much cheaper.

Even though you may have to read edit your song files,But once your are done tweaking them to your liking then there is no need to do anything than just play them.

Just a few ideas to get you thinkin'!

jer

[geraldfryjr]

This is off subject as far as passive crossovers but here are a couple of threads as to what I was talking about.
These links are to the beginings of the threads as one was started in 2005.

Enjoy! jer



Is anyone using DRC?

A how to for a PC XO.

[dochungwell]

Wow...very interesting alturnative! I may utlimately head in this direction. I would like to eventually transfer all my music and video onto a media server platform.

[Calvin]

Hi,

the effort using passive xovers is of course considerably smaller, but a well designed ESL is capable of revealing their associated sonic deficiencies.
Besides less effort the passive circuitry can ease the amps pain and difficulty to drive the ESL and it may even be the better solution if the amp sucks -and believe me....in the struggle to drive a ESL properly app. 95% of all amps suck. It´s a delicate task to design or even to find a ESL-capable amp. Besides driving the ESL stable under all conditions it should sound superb under any load. ESLs present a load under which most amps fail to deliver their best sonic performance. Traditionally Tube amps are said to be less critical with ESLs and I usually get the best results with single-ended triodes wo global feedback, which unfortunately feature the worst price/wattage relationship of all amps.
If You wanna design a passive Xover I´d recommend to get a believable and workable set of measurements of Your panel and use simulators like LT-Spice or one of the better speaker simulators like LSPCAD. With LT-Spice You need to model the impedance the amplifier sees. Simple formula-based calculators don´t work at all, not even for dynamic speakers. Standard Xovers also fail in doing the job.
ESLs need dedicated Xovers, exclusively designed to be used with those.
The same applies to active Xovers. Standard active XOvers consisting of a set of fixed filters (often just the frequency is tunable) generally don´t work well. This is one great advantage of digital filters, that they may be parametrized individually and flexible. Digital FIR-filters are not necessarily a major improvement, even they offer signal shaping like no other (some even allow for room-correction, etc). Handling and programming is much more complex than with the consderably cheaper IIR-filters. The pinhole of all digital filters are the A/D and D/A conversion and the associated analog stages.
If staying analog, an OPamp based filter should only be used for testing or used with dynamic speakers. Apart from numerous Filter cookbooks on the Net they have no real advantage over discrete Buffer-Filters, neither size nor cost and certainly not sonic-wise. ESLs demask OPs as technical devices not musical ones. Simple discrete Buffer based (e.g JFET-Buffers) or Tubes Xovers preserve music´s flavour.

At the time You´re still at the beginning of Your ESL experience. I recommend You continue with passive filtering and a good stable amp and upgrade to active systems in the process of gaining knowhow and experience.

jauu
Calvin

[dochungwell]

Hello Calvin, Thank you for sharing your suggestions and insight. I will bookmark your suggestions for future reference as I continue to learn all I can as to ESL characteristics, and application of sound shaping equiptment...there is much to learn!

Regards,
Jerry