Planar Speaker Asylum Welcome! Need support, you got it. Or share your ideas and experiences.

---

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Planar Speaker Asylum ]

---

[ Alert Moderator ]

---

ESL-57 and AMC CVT-2030 amplifier observations

Posted by BillMilosz on August 4, 2007 at 19:19:30

I tried an AMC CVT-2030 with my ESL-57's for the past week or so and I like the sound. The AMC CVT-2030 is kind of a strange amp, they have EL-34's that are SOLDERED IN. (The amp is available at extra cost with sockets)- they use low speed fans to cool the tubes and their thinking is the tubes will last for years as they are run a little below maximum specs and have fans....but I dunno. I bought the thing on eBay for cheap and if it stops working I will just solder in some new tubes I guess. Or maybe put in tube sockets, who knows. It's working NOW....

Anyway - the sound- in comparison to my Dynaco ST70 (see note, below) it sounds like it doesn't have quite as much power available at low fequencies before distortion sets in, but it sounds like the AMC goes a little lower in extension... kind of paradoxical, I know, but that's how it sounds on my ESL-57's. For sure the bass on the AMC has better texture. Maybe better damping factor in the AMC? Who knows.

The midrange on the AMC is very good; not quite as "warm" as the Dynaco ST70, but has great buttery smoothness, liquidity, and all that other El34 good stuff.

The highs on the AMC are much nicer than the ST70- more detail, and this gives a more layered soundstage etc., as well as adding more realism to the midrange's overtone presentation. I suspect this is the MOSFET driver in the AMC doing it's job. The AMC does NOT sound like a solid state amp, it still has tube sound, and the highs do not glare or sound grainy.

I am using the 4 ohm taps on the AMC. The 8 ohm taps sounded too rolled off in the HF region.

If you have ESL-57's and have an opportunity to get an AMC-2030 cheap, you might find it very satisfactory. It's very musical.

I would suggest you adjust the bias and offset on any AMC2030 you buy, but be careful the pots are VERY touchy. Procedure can be found at http://lf.org/milosz/files/cvt-2030adjustments.pdf CAUTION- LETHAL HIGH VOLTAGES PRESENT!! Poke around in there with the power on ONLY if you KNOW WHAT YOU'RE DOING.

NOTES:

OTHER AMPS I'VE USED ON MY ESL-57s: Dynaco ST70 stock topology but with passives replaced with audiophile stuff like MIT Multicaps, film resistors, etc.

SUGDEN-A25a - my favorite solid state amp for the ESL-57's at the moment. Better bass than tube amps, but still has tube-style midrange magic. Highs excellent, but a little "etched" compared to tube amps.

MONARCHY SM70 PRO - pair run as monoblocks. Very good sound, near flawless. More accurate midrange than the Sugden, but the Sugden's midrange coloration is something I actually LIKE.

NAD 2400, NAD 2600: kind of dark sounding but good. Better sound than most other mid-fi solid state gear.

ADCOM 555 MK II, Parasound HCA1000a - better than most other solid state amps, not quites as dark as the NADs.

MARANTZ 240 , YAMAHA A-700 - OK, but no midrange "magic"

Yamaha CA-800 VERY good in Class A mode, expect it's underpowered when run this way. (~5 watts) - otherwise par for the solid-state amp course.

This post is made possible by the generous support of people like you and our sponsors:

Sonic Craft

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---