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November 4, 2019

Hi Everyone! It has been a while since the last update. As many of you probably have experienced, ESLs will bring to light any insufficiencies in the rest of your system. As a result of that, I have been working on the rest of the system. Here is a little of what has been going on:


OK, I have fully fallen down the amplifier rabbit hole. It is a very nice rabbit hole, with many wonderful people here, but it is a rabbit hole nonetheless. When you understand that, you will understand why it has been a couple years since that last update.

I had been using a really nice, old MOSFET amp from Soundcraftsman, and it was able to deliver very sweet mids and highs, but, the impedance of an ESL at the low end is terribly hard to drive. The lowest impedance over the spectrum for my ESLs is just under 1 Ohm at about 48Hz. I have the subs crossed over at 50Hz, so the lowest bass is OK, but the bass from there through about 150Hz was very thin. I don't listen at really high volume levels, so my power needs are modest, but even modest power levels at 8 ohms get out of hand at 1 Ohm (e.g. 100W at 8 Ohm = 200W at 4 Ohm, 400W at 2 Ohm, and 800W at 1 Ohm).

So, I did what every good DIY'er does, and started by pouring through diyaudio.com. Just as with the ESL project, I went through several iterations and topologies, but finally ended up with a design based on Nelson Pass' F5. I built it as a pair of mono blocks. It was impractical to get that much capacity for both channels into one box.

I have to tell you, the difference is huge! This amp is just what is needed to drive the ESLs. The peak current capability is about 42A and it will drive 75W @ 8 Ohm down to a 1 Ohm load continuoulsy, 20Hz to 100Khz. The mid-bass is tight and authoratative. The mids and highs are effortless. Thank you Nelson Pass!

It was a ton of work to get everything going and looking nice. You can buy everything you need to get an F5 Turbo running at the DIY Audio store, but I am sort of crazy about doing things myself (the hard way).

Here are some photos:

April 20, 2017


While the Full-Range ESL project is technically "Full Range", it drops of significantly below about 45Hz. There is a whole range of music in that bottom octave, and I had found that without such content, the musical experience was lacking. After much research, I decided on a Rythmik subwoofer. The advantage of this is that they offered amp/driver combos that I could put into my own case so that it matched the look of the ESL. I especially liked the servo motional feedback aspect that produced a very tightly controlled response that worked extremely well with the quickness of the ESL.

If any of you want more info on these types of subwoofers, just drop me an email.

Ken Seibert
Redondo Beach, CA