Preface
January 2017 (Updated January 2024)

Welcome to our Joule-Electra info page! Joule-Electra was founded in the early 90’s by Jud Barber and his late wife Marianne. Though their construction was somewhat unconventional, their all tube preamps and OTL tube power amplifiers quickly earned a acclaim and a following for their wonderful musical and sonic characteristics. Jud Barber was not a young man when he started Joule-Electra though and during 2013 (6 years after the passing of his beloved wife Marianne), he retired and closed Joule-Electra. Jud Barber has left us in 2022 having led a long life, but I keep his audio legacy alive here.

Since the company’s closure, I have taken on the role of Joule-Electra guru. Putting my technical and (Electrical) engineering background to work along with some training I had received directly from Jud on his gear, I provide support (i.e answer questions), service, and upgrades on almost all Joule-Electra gear. I also stock most of the unique tubes (6350’s, 6EM7’s, OA2’s and others) that Jud used in Joule-Electra products over the years. I don’t think anyone else has quite the breadth of knowledge of Joule-Electra gear. Whether you just want to give your old LA-100 a checkup and bias, or your need your VZN-100 repaired, or you want to upgrade your LA-150MKII or SE to my version of Joule-Electra’s LA-300ME Platinum (a true reference level preamp), I can help. References are available. My hourly labor rate is $125 per hour (and due to the physical size, weight, packaging, and logistics of working on the larger Joule -Electra OTL amps [VZN-160 and larger] that hourly rates is $150 per hour). There is a minimum 1 hour charge (keep in mind it can take longer than that to just unbox and set-up a pair of VZN-220 OTLs just to inspect and test them!) when working on Joule Electra gear.

A word about service documentation, schematics, parts lists etc. There really is not much if any proper documentation (schematics, parts lists etc) for Joule-Electra gear. Jud was very old school and kept much in his head, and what little information I have are poor photocopies of parts of circuits drawn by hand – much of which are hard (remember I am a Electrical Engineer) to make heads or tails out of!!! As well, what I was given personally by Jud when I visited Joule-Electra some years ago was given in confidence (for my use/eyes only). Though Joule-Electra the company may be gone, I intend to honor that (my promise to Jud).  There are NO complete schematics nor do I have a parts list of ANY kind of Joule-Electra gear (and as far as I know they do not exist). Service work on Joule gear often means a certain amount of head scratching and tracing things out with multi-meter in hand, sometimes comparing a working good channel or preamp/amp to the bad one and/or relying on my experience with other Joule-Electra gear I have worked on. Fortunately in the last 10+ years, I have also built up a certain level of baseline knowledge in how Joule-Electra gear works and is designed, so many things are not quite the mystery the once used to be BUT keep in mind that does not mean I can tell you what is wrong with your preamp and power amp after you described the problem(s) you are having to me over the phone/e-mail.

I wrote what almost all of what follows below 10+ years ago. I tried to put together a definitive collection of info, reviews, notes, personal experiences, etc of this wonderful line of products.  I went through my Joule papers back then and created this library of reviews, documents, and price lists towards the bottom of this page from items that I have scanned and/or converted to PDF. You will have to scroll down (I know, horrors! LOL) to get to this list. I have kept all this available as reference resource for current, former and future Joule-Electra product owners. Enjoy and feel free to contact us with any questions your may have.

Rich Brkich, Owner, Signature Sound

Introduction

I have been a big fan of Joule-Electra gear for many years. I have been captured by the dimensionality, purity, and musicality of their products since I first heard them some ten years ago. Over the years I have come to know the talented southern gentleman and his lovely wife (Jud and Marianne Barber) who are Joule-Electra quite well. Here is a guy who in his younger years, eschewed pursuing a education in electrical engineering because he did not want to make his love and passion for music and vacuum tube circuits his daily work. Instead he pursued a  degree chemical engineering (acing all his electrical engineering elective courses of course) followed by successful career in chemical and plant engineering. Towards the end of his career he took his thoughts and ideas from many years into products and started Joule-Electra. The LA-100 preamp quickly garnered a reputation for its ability to portray a palpable soundstage and a wonderfully natural sounding tone and their OTL amplifiers started changing minds about the resolution and purity of tone capable by tube power amplifiers.

Since picking up the product line in the late 90’s, the Barbers have become like family to me. The Joule Electra preamp (first a LA-100, now a LAP-150) has long been the heart of our reference system here at Signature Sound. The crown joule (pun intended) of the Joule-Electra line up is their marvelous OTL (Output Transformer Less) tube power amplifiers which are quite frankly, in my estimation, the finest audio amplifiers on the planet. Signature Sound has a wealth of experience with the wonderful VZN series of amplifiers from Joule-Electra. We have sold and delivered many pairs (including the first pair of VZN-220 “Right of Passage” monoblocks) of  them over the years and I have received personal training from Jud Barber on the design and manufacturer of their products during my visits to their company/home. While some dealer(s) may have “sold” more Joule-Electra products than Signature Sound over the years, you will find no other dealer as knowledgeable as us when it comes to the sound, operation, maintenance, fabrication, and design of Joule-Electra products! – Rich Brkich, Owner, Signature Sound

What is a
OTL Amplifier?

While vacuum tubes are a fairly old technology and are pretty much missing in modern everyday life because of the compactness and high efficiencies capable of solid state devices, that does not mean they have no value or use. In fact, many enthusiasts have have praised and still enjoy the sound qualities of vacuum tube based power amplifiers in this day and age. Vacuum tube based power amplifiers enjoy great popularity in the specialty (hi-end) HiFi marketplace and pro-audio marketplace (just ask any serious electric guitar player!).  Since vacuum tubes are mostly great voltage amplification devices, traditional vacuum tube based amplifiers need a way to convert the relatively high voltage and low current output to the (generally) lower voltage and higher current needed to power a loudspeaker. You audio geeks out there know that a (output) transformer is used to accomplish this task. Transformers work pretty well (as a great number of fine sounding vacuum tube amps prove), but they do have their limitations: they are bandwidth limited; heavy (lots of metal laminations with coils of wire wrapped around them); have phase distortion out towards their top and bottom response limits; and need to be operated within the linear region of their magnetic circuit.

While it is not easy or particularly efficient, a vacuum tube can directly drive a loudspeaker. There are a few tubes out there that have enough current output capability (especially when teamed up with several other tubes of the same type) to directly drive a loudspeaker – completely doing away with the voltage to current transforming device. This is where the term OTL comes from… as these special amps are Output  TransformerLess. Now for those of you who want to get technical/clever… yes, just about all solid state amps are “OTLs” but traditionally OTL amplifiers are amplifiers that are vacuum tube based with the tubes directly coupled to the load/speaker (no inductors, transforming devices/circuits, transformers or capacitors in the output path of the amp). The benefits yielded in a OTL amp is that mainly there is no phase distortion or bandwidth limitations. The tube amplification circuit is allowed to be heard in all its glory without interference between it and the speaker. Are there trade-offs with the OTL amplifier? Yes. They are not typically efficient. OTL amplifier topologies generally use Class A triode output stages and require more tubes than conventional transformer coupled tube amps that use more efficient (generally not pure class A) circuits to generate the same amount of output power.  Also, OTL amps are not well suited for driving speakers with very low resistance (impedance) as they loose power as the speaker impedance drops to very low levels unless the OTL amplifier is made very large (and hence very expensive) in power output capability.

Now, not all OTLs are alike. There are a couple of different OTL circuit topologies used over the years (one of which had a reputation for poor reliability). Joule-Electra uses the most reliable and stable OTL topology which is generally called the Circletron. These are not easy (or inexpensive) to build though… differential input stage and floating power supplies require good engineering and execution to deliver great results. We believe Joule-Electra’s VZN series of OTL amps are the best OTL design out there. Their selection of the extremely rugged Russian 6C33 triode tube provides great sound and ensures many thousands of hours of reliable operation (two or three times of that of conventional output tubes). The use of  wood based non magnetic chassis, top quality parts chosen for the best sonic characteristics, point to point wiring, use of damping & isolation materials on chassis and circuit boards, continuously adjustable feedback controls, easy to use and adjust individual bias controls, and use of a variac in part of the power supply to carefully maintain the optimal filament string voltage for the output tubes are just some of the things that make the Joule-Electra VZN series of OTL amp’s so special. The proof is in the listening of course and that is were these amps deliver the goods like no other amplifier can.

Refined – Not Redesigned

A quick note or two about the Joule-Electra design philosophy as I have learned it from Jud Barber over many conversations during the past years. The core circuits of Joule-Electra gear (the Mu follower used in the preamp and the class A triode based circletron topology used in the amps) have remained constant ever since the amp and preamps introduction. Instead of trying to reinvent the wheel every few years as many other manufactures do, Jud Barber has regularly evolved the workings around the core circuit topology to make the OTL amp and preamp perform better while maintaining the fundamental harmonic integrity which their products are famous for. This does not mean that Jud Barber has not investigated other circuit topologies. Jud has shown me pictures of several different prototype gain stages he has tried…. only to reject them because they simply do not work or sound as good as the designs he currently uses.

Some examples of the refinements made over the years include: The Music Wood OTL amplifier enclosures; shunt to ground volume control; and improvements to the power supplies of the amplifiers and preamps. A number of the improvements are discussed in the literature we have listed below for your review (there is not enough space or time for me to get into a discussion of those details here) so feel free to peruse that info at your pleasure! The new Marianne Electra Memorial Edition preamps incorporate even further refinements with custom made wiring and some  extremely good sounding passive parts (unfortunately these parts and wire are very expensive so these preamps are new models made in addition to the existing products) to take the pre-amps sound to a even higher level (again, you can find details in the literature and info links listed below).

Joule-Electra Links & Literature Library

Joule-Electra was not much for very fancy or slick literature, but I have a collection from over the years which Jud Barber has put out. All the links below open up into a new window.

• Joule-Electra LA-150 Special Edition Preamp – An overview of the improvements incorporated into the LA-150MKII preamp from the LA-300ME in the LA-150MKIISE. (Web page generated from Joule-Electra literature).

• Joule-Electra LA-300ME Preamp Overview – Webpage overview with detail info on specs on this special preamp! (Web page generated from Joule-Electra literature)

• Joule-Electra OPS4 Memorial Edition Phono Preamp – A webpage overview of the new OPS-4 all tube phono preamp (Web page generated from Joule-Electra literature)

• Joule-Electra LA-300ME (Marianne Electra Memorial Preamp) Literature – From the intro of the preamp at 2009 CES, a overview with some internal pictures of the new preamp. Adobe PDF file. (PDF)
  

• Platinum Upgrades for LA-150SE, LA-300ME and LA-450ME Description & Pirce Sheet – Circa 2012, Jud and his “consultant” the late Simon Thacher (Simon Vinitski) developed a further upgrade for the listed preamps. My understanding is that only one or two LA-150SE’s received this upgrade and less than a handful of LA-300ME (and only one LA-450ME)  were made or upgraded to Platinum level. This info sheet describes the basic details and prices of the Platinum upgrade. (PDF)
  

• Joule-Electra LA-150MKII Design Goals. – Circa 2006, a look at the design goals behind the new LA-150MKII line stage preamp as seen by Jud Barber. (Web page generated from Joule-Electra literature)

• Joule-Electra LA-150MKII Line Stage Overview – Circa 2006, an overview of the latest version of the famed Joule-Electra line stage excerpted from the new preamp’s owners manual. (Web page generated from Joule-Electra literature)
  

• Joule-Electra Product Line Overview Literature – Circa 2005, a brief introduction to Joule-Electra preamps and OTL amps. Two page Adobe Acrobat (PDF 750 KB).

• Joule-Electra OTL Power Amp Literature – Circa 2005, a brochure on the Joule-Electra OTL power amps and the Musicwood enclosure with many pictures. Four page Adobe Acrobat (PDF 1.85 MB).

• Joule-Electra Product Line Brochure – Circa 2003, a brochure that covers the first version of the LA-150, the Stargate amps, and a listing of the OTL amp line-up available at that time. Four page Adobe Acrobat (PDF 1.2 MB).

• The Absolute Sound HP (Harry Pearson) Comments on the VZN-220’s – Circa 2002, The HP from the Absolute Sound didn’t do a full review of the Rites of Passage as Jud’s biggest VZN-220 OTL’s were called, but wrote comments in two issues of TAS on the amps which he had for a period of time. (PDF)

• Joule-Electra LA-150 New Product Announcement – Circa late 2001, this one page information sheet announces the LA-150 (the MKI Russian tube line stage version) line stage preamp. (PDF)

• Joule-Electra Product Line Brochure – Circa 2001, a brochure on the whole line-up including the now discontinued VAMP hybrid amps. As well, there is info here on the LA-100MKIII and Heavensgate/Stargate power amps. Four page Adobe Acrobat pdf (1.5 MB).

• Joule-Electra VZN-220 OTL Amplifier Overview – Circa 2000, a interesting in depth look at one of Joule’s largest amps with some interesting interior photos of the OTLs (prior to the new circuit board design and Musicwood enclosures found in more current MKIV versions of the amps). Two page Adobe Acrobat pdf (350 KB).

• Joule-Electra LA-400 Balanced Line Stage Preamp Info Sheet – Circa 1999, this is a one page information sheet that describes the balanced version of the LA-100 line stage preamp. The LA-400 is based on two LA-100 line stages to make a fully differential balanced preamp. (PDF)

• Joule-Electra Preamp and Power Amp Picture Sheets – Circa 1999, Three pages of various pics of the Joule-Electra preamps and power amps made at that time. (PDF)

• Joule-Electra 1997 Letter to Signature Sound – Circa Summer 97, this two page letter announcing and giving a bit of  the tech details on the MKIII versions of the OTLs, the LA-100 line stage, and the OPS phono preamp that Jud had in the works at that time (PDF).
  

• Joule-Electra Music Begins With Mu Literature Sheet – Circa Late 90’s, this is just a couple of paragraphs from Jud on Joule-Electra’s use of the Mu follower topology found in their gear (PDF).

• The Absolute Sound Review of the VZN-160 Gran Marquis OTL Amplifiers – Circa 1998 or 1999, we have the HP (Harry Pearson) giving the (at that time) Joule-Electra’s biggest amp a full review (4.5 MB PDF).

• The Absolute Sound Review of the LA-100MKIII Preamp – Circa 1999, a early review by Mike Kuller  who compares it with the Audio Research LS-16 with a follow-up by Scot Markwell (2.8 MB PDF).

• .Joule-Electra VAMP Integrated Amp Introduction Info Sheet – Circa 1999, a two page handout from 1999 CES which introduces and gives a bit of a tech overview of the short lived hybrid integrated amp Joule-Electra made for a few years.  I recall there being a MKII version too. (PDF)

• Joule-Electra The Awful Truth About OTLs – Circa 1997, this is Jud Barber’s thoughts on the strengths and what makes for a good speaker load for a OTL. (PDF)

• Joule-Electra Why Tubes – OPS Phono Preamp Introduction – Circa the late 90’s I think, this is seven page hand-out contains Jud’s thoughts on why tubes are the best way to go in the first  3 pages and the rest is a introduction and design overview of the Jooule- Electra OPS phono preamp. (PDF)
  

• Joule-Electra Introduces the LA-100MKII and LA-200 Preamp – Circa 1995 or 96, this one page information sheet announces the MKII version of the LA-100 and also introduces its fancier looking brother, the LA-200. (PDF)

• Joule-Electra VZN-100 Marquis (original version) Info Sheet with Pics – Circa mid 90’s, this is a one page info sheet on the first version of the VZN-100 Marquis OTL amplifiers. (PDF)
  

• Positive Feedback Review of the VZN-100MKII OTL – Circa 2003, One of the more recent reviews of the Joule OTLs. Old friend, David Robinson – Editor of PF On-line, does a wonderful job here (link to Positive-Feedback.com review web page).

• Soundstage Review of the OPS-2 MKV Phono Preamp – Circa 2001 review of Joules best phono stage by Bill Cowan (link to Soundstage.com review web page)
  

• Positive Feedback Magazine LA-200 Review by Bob Sireno – Circa late 90’s (I think), this review take a look at the dressed up version of the LA-100MKII preamp. This is a PDF made from a rather poor photocopy of the review, so the print quality is not that great. (PDF)

• Joule-Electra Price Lists – A PDF of six Joule-Electra retail prices sheets spanning the years from 1997 to 2009 (3.0 MB PDF).

Below prices are from the last retail price list I received from Joule-Electra. These are circa 2009 (see the bottom price list in the above price lists PDF). As time went buy, Jud did drop the price of the Marianne Electra (yes, that was Marianne’s middle name) Memorial gear some… for example, The LA-300ME when first released I was told it would be $14,800 MSRP!!!!  As you can see was adjusted to  $11,995 and for a short period of time I have a e-mail from Jud listing the price as $11,500 MSRP and I think a couple were sold direct by Jud at around $10,000. The MusicWood enclosure option for the OTLs various depending on the amps and the size of the chassis. For example, on VZN-100’s the MusicWood option was generally $3k and on VZN-160’s $4k (I think).

Preamplifiers and Phono Stages

• LA-450 Marianne Electra Memorial Fully Balanced Preamp W/Remote: $18,995

• LA-300 Marianne Electra Memorial Preamp W/Remote: $11,995

• LA-150 MKII Special Edition W/remote: $6,995

• LA-150 MKII line stage w/remote: $5,250

• OPS-1 MKIV all tube phono stage: $3,900

• OPS-2 MKIV all tube phono: $4,400

• OPS-4 Marianne Electra Memorial Phono Preamp: $8,800

• LAP-150 MKII w/OPS-1 inside w/remote: $9,600

OTL Power Amplifiers

• VZN-80 MKV (Emerald) Stereoblock: $12,000 ea

• VZN-100 MKV (Marquis) 100W Monoblocks: $15,000 pr

• VZN-160 MKV (Grand Marquis) 160W Monoblocks: $18,000 pr

• VZN-220 (Right of Passage) 220W Monoblocks: $24,000 pr

• VZN-350 (Destiny) 350W Monoblocks: $30,000 pr

Options for OTL Power Amplifiers include: 220 or 240 volt power supplies – $1,000; Solid Wood (Musicwood) chassis – Price On Request. Musicwood chassis are available in a variety of woods (straight grain Sitka Spruce, straight grain Western Red Cedar and Maple) finished in with premium automotive clear coat finishes.