Information for Joule Electra LA100 Mark III

I have the manual and the instructions for biasing the tubes. Email with your address.

I bought an LA-200 (based on the serial number the first unit made) about a year ago from the person who originally reviewed the preamp in PF (the review is on the Joule website). I sent the preamp to Jud and he upgraded it to an LA-100 MkIII. Other than cosmetics, the LA-200 and LA-100 were pretty similar. The LA-200 was top of the line until the signal path circuitry was changed and the LA-100 MkIII was released (6350 Mu follower replaced the 5751). The main differences were in the output impedance, where the LA-200 was not recommended for use with amps under 100k ohm input impedance, and gain where the LA-200 had slightly more gain than the LA-100 (although on both preamps this was adjustable, the LA-200 uses 4 rocker switches in 2db increments and the LA-100 has jumpers for 2 settings).

The only other difference was the power supply tubes where the 10EM7 tubes found in the LA-200 became obsolete and instead the 6EM7 was used in the LA-100 MkIII (I believe earlier versions as well but not sure). Both preamps were offered with the Purist Audio wiring option (versus stock Cardas) and remote option. The LA-200 was stereo only and the LA-100 featured a Stereo/Mono switch. Also, I believe you could stipulate dual volume controls or volume/gain controls for each unit, although mine is dual volume and Jud recommended I keep it that way.

Both these preamps are warmer and more musical than the LA-150 which uses the Russian tubes. I think the LA-150 is a great preamp, but there are many more preamps like it, some like the Herron that outperform it. For the money, the LA-200 or LA-100 MkIII is tough to beat in its price range, especially used.

The MKII version of the LA-150 has a richer more musical sound than the earlier versions. The gain stage uses all 6350's (no more Rusian tubes)but otherwise is identical in topology to the original 150.

Jud Barber - Joule Electra

Jud,

Good to see you posting here!

David Berry

Wow... it is good to see Jud posting here.

I have an original LA-100 Mk III with Purist wire and Remote options (not an upgraded unit) and I absolutely LOVE IT!

I even sent it to Jud last fall to add an additional 3db's of gain (new jumper added).

Amazing preamp.

I 2nd (or is this 3rd or 4th?) the motion - I find it superior to units costing $2-3,000.00 more as I'd owned or borrowed four other such units. It is the most musical and enjoyable pre-amp I've owned and is well worth the cost. Simply disappears behind the music. Just wish the remote control was more precise.

Glad to hear the latest version of the LA-150 does not use the Russian tubes in the gain stage. I unfortunately sold my LA-100 MkIII recently as a result of having to downsize my system a bit to move into smaller quarters and truly miss the preamps musicality in my system.

Jud - if you're following this thread can you elaborate on whether there is an upgrade path to move from an early LA-150 to the MkII version. Thanks

The original LA-150's can be upgraded to the MII but the hand ful of LA-100's that were converted to the 150 topology cannot. There is not enough room on the signal board to accomodate the extra tube.

Jud Barber - Joule Electra

Thanks Jud, hope to see you at RMAF later this month.

Thanks for the kind comments guys. We love two channel audio and hope it survives the current crunch!

Jud

Hello.
I recently got a LA100 mklll and I’m loving it. I can’t find a manual for it anywhere. I’m curious about the specs for matching it with a correct amplifier, also about these jumpers mentioned for increasing the gain. Any help would be appreciated!