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Solid-state guitar amplifier history -thread

Started by teemuk, April 16, 2007, 09:12:15 AM

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One of my hobbies besides electronics and music has always been history so I decided to start a thread that would gather some of solid-state amplifiers. As you all likely know, there is a lot written about tube amplifiers and it's a crying shame that so much of solid-state guitar amplifier history has been left undocumented or has been forgotten. Maybe this forum has gathered enough enthusiastic people to find the topic "sexy" enough.

In the future, I'll be updating this post once in a while to summarize and add new information. I'm looking forward to your contributions as the timeline and details are still pretty much "lacking".

The 50's:

  • (Likely) the first transistor radio is unveiled by Intermetall in Düsseldord Radio fair. First commercial transistor radio, the Regency TR-1, is put to sale the next year.


  • Lin introduces quasi-complementary output stage topology (this is output transformerless).
  • Paul Penfield's article "Transistorized Guitar Amplifier" appears in July issue of Radio & Television News magazine.

The 60's:


  • Standel releases first hybrid amplifiers. I know Bob Crooks found Standel, built and designed many of their early tube amplifier models but what about the solid-states? Did he get some design help?


  • Kay's "Vanguard" line-up: The first all-transistor guitar amplifiers? Any info on the designers?
  • First fuzz box, Maestro FZ-1 Fuzz Tone, appears.


  • Leak Stereo 30: First commercial output (and interstage) transformerless transistor (HiFi) amplifier.
  • Hagström introduces Model 1700 - also known as "GA-85". Some people think this is the first all-solid-state guitar amplifier, it's not. (And some sources state that this model was actually introduced as late as in 1965). Any info about the designers?
  • First Burns transistor amplifier. This is likely the "Orbit" model; Around this time it costed more than a new Vox AC-30.
  • Likely the first Gibson transistor amplifiers: "Starfire"-series including TR-1000RVT and TR-1000T. This information is based on to earliest catalog entry (from 1963) I've seen concerning Gibson SS amps.
  • Czechoslovakian company called Jolana introduces the "Big Beat"; a guitar with an integrated SS amplifier and a medium wave radio. The battery-powered circuit is the first reference to a completely transformerless SS guitar amp design I've seen so far.


  • First Vox transistor amplifier (T-60). Any info about the designer? Tom Jennings, Dick Denney?
  • First WEM (Watkins Electric Music) transistor amplifiers emerge. The "Slave" PA system caughts a notable success but their lineup of transistor guitar amplifiers (introduced ca. 1966) can not compete with the new "rock" amplifiers.
  • First commercial digital amplifier (Sinclair's X10 DIY kit).


  • Hartley Peavey founds Peavey. Earliest amplifiers were designed by him and (ex RCA designer) Jack Sondermeyer.
  • Jennings looses control over Thomas Organ Company that switches from supplying imported UK Vox amplifiers to building their own. The transistor models are manufactured and designed at La Sepulvenda laboratories. Any info about the designers?
  • First Carvin solid-state amplifier: T-11. Carvin also introduces other transistor amplifiers such as T-12, T-4-102, T-2-101, T-151 and T-121. (http://www.carvinmuseum.com/decade/65-guitaramps.html)
  • First Standel transistor amplifiers.
  • First Selmer transistor amplifiers. (First one was likely the Taurus 60 that later changed its name and appearance becoming Saturn 60).
  • Likely the first all-solid-state Univox amplifier, BT505 bass, appears. The following years, Univox did produce a lot of hybrids but the all-solid-state guitar amplifier lineups were introduced as late as in 1971. http://www.univox.org/pics/catalogs/1965_amp_catalog4.jpg
  • First Baldwin transistor guitar amplifiers. Baldwin had just bought Burns so there were models under both Burns, Baldwin-Burns and Baldwin names. Since Baldwin originally had no expertice in making guitar amps it's needless to say that at first Burns practically just continued to manufacture its existing designs under the Baldwin name. (More information follows later in this thread).
  • Dallas transistor amplifiers appear.
  • Rolling Stones: "Satisfaction". This hit launches a craze for fuzz effects.


  • Bud Ross founds Kustom. Ross was the head designer and founded Road Electronics when Kustom was sold. Road Electronics manufactured high quality transistor guitar amplifiers and later merged with Rickenbacker that produced a series of "Road" amplifiers. Ross has also manufactured police radars and (Ross) guitar pedals.
  • Fender releases their first solid-state amplifiers. These are designed by Bob Rissi and suffer from poor build-quality and field failures.
  • Gibson introduces the transistor GSS-series consisting of models: GSS50 (2x10" combo), GSS100 (head with two 2x10" cabinets) and Plus 50 ("slave"-style 2x10" combo amp). Daughter brand Epiphone introduces the "Maxima" amp, which is a GSS100 copy.
  • First Sears Silvertone transistor amplifiers appear (Models 1464, 1465 and 1466 Bass). These are manufactured by Danelectro. In 1968 the same line-up has inclusion of model 1463.
  • First Jordan transistor amplifiers.
  • Teneyck transistor amplifiers: The G-series. These are designed by Bob Teneyck who also worked for Ampeg (design of Gemini series plus patents for Ampeg's vibrato and tremolo) and designed for Sunn (see 1969 "Orion"). Next year (1967) the T-series of amplifiers is introduced.
  • Mosrite introduces their lineup of transistor amplifiers and fails commercially with the Award BG-500 "The Ventures" model..
  • First solid-state Triumph amplifiers appear.


  • The Popular Electronics magazine introduces many popular and influential kits: i.e. M/M/M Instrument Amplifier.
  • Likely the first transistor Premier amplifiers are introduced. (i.e Model 5530)
  • First all-transistor Magnatone amplifiers appear.
  • Baldwin buys Gretsch.


  • RCA releases application notes describing quasi-complementary and differential input stage topologies. These are highly influential and give a start for numerous small (and bigger) companies manufacturing transistor guitar amplifiers.
  • Transonic line-up from Rickenbacker: These were also designed by Bob Rissi (designer of first SS Fender amps). However, this time most mistakes of Fenders are corrected. Transonic amplifiers are high quality but fail to catch large success; they are endorsed by Steppenwolf and used by Led Zeppelin (US tour) and Jeff Beck. Rissi continues to design and build guitar amplifiers in Risson. Today Risson makes "boutique" tube gear but assumably the first amplifiers (in 70's) were solid state.
  • First Acoustic Control Corporation transistor amplifiers are introduced. Acoustic's designers, employees and founders are fairly well known: Steven Marks and Harvey Gerst, Russ Allee and Roger Smith (the duo later found Amplified Music Products or AMP), Steven Rabe (later found SWR), Gene Cerwinski (later founder of Cerwin-Vega) and Aspen Pittman (sales, later found Groove Tubes) are few of the most famous.
  • GMT 226A, designed by Bob Gallien, is the first instrument amplifier that uses a stacked power transistor configuration ("cascode" or "beanstalk"). The following year Carlos Santana uses the amplifier in Woodstock.
  • Tommy Gumina founds Polytone.


  • First solid-state Sunn amplifier "Orion" is designed by Bob Teneyck. This amplifier is endorsed by Jimi Hendrix but proves to be a commercial disappointment due to many field failures. The following Sunn transistor amplifiers are designed by Dick MacCloud from Tektronics.
  • Fender SS Super Showman. Interesting is the fact that this was designed by Seth Lover, the inventor of humbucking pickup (and the P.A.F.-type as well). The former employee of Gibson was hired by Fender in 1967.
  • Ovation and Lawrence transistor amplifiers appear.
  • Anthony Leo's article in Electronics Australia introduces Playmaster 125 (PM125), another SS guitar amplifier kit. http://ozvalveamps.elands.com/playmaster/pm125-1pcase.jpg

The 70's:

  • (possibly?) Sears Silvertone "slant control panel" SS guitar amplifier models 1422 (originally tube), 1423, 1425, 1426, 1428 and 1431 are introduced. These are last Sears Silvertone guitar amplifiers, basically bargain bin quality and not manufactured by Danelectro. The Silvertone brand name eventually died after 1972.
  • Kustom establishes a daughter brand of amplifiers called Kasino. Daughter brands such as Krossroad or Woodson are established later. While Plush/Earth Sound Research amplifiers bear cosmetic resemblance to Kustom's products they were actually clones of Fender or Peavey tube amplifiers.



  • First transistor Marshall amplifiers. These are JMP-series: 1994 Slave, 2077 Bass 100 and 2078 Lead 100 Combo. They are followed by more JMP-series amplifiers in 1975/6: 2098 Master Lead, 2099 Bass, 2195 Lead & Bass, 2196 Lead & Bass, 2199 Master Lead Combo, 2200 Lead Combo, 2201 Lead & Bass and 2299 Master Lead Reverb. Any information on who were the designers?


  • GMT 200G is the first channel-switching amplifier
  • Unicord (Univox) introduces "Mobile Ohm" series that are equipped with load impedance selector and E.S.P (Electric Short Proof) short-circuit protection. Models: U-130 Bass, U-130L Lead, U-130PA, U-200L Lead, U-200B Bass and U-600PA. http://www.univox.org/pics/amps/u130pa.jpg


  • Roland's Jazz Chorus line-up is introduced. During the years, Roland has released at least eight or nine new versions of this amplifier - some completely different from another. Their website hints that the real model name is depicted as JC-120-xxx, where xxx is an obscure letter code not explained anywhere (i.e. JT, U, UT). Anyone has more info?
  • Marshall releases first transistor heads.


  • The concept of rail-switching amplifier (class G) is introduced and used next year by Hitachi.


  • Sunn Beta series is the first commercial product utilizing overdriven Logic IC stages. (Fairchild app notes discussed the concept already in 1973). The amplifier also uses IC switching circuitry instead of FETs. Any info on the designers? The "logic inverter distortion" circuit is later (1978) popularized by an article written by Craig Anderton (before his book) and used in Electro-Harmonix "Hot Tubes" pedal.
  • Unicord (Univox) introduces "Stage" amplifiers (1977 - 1980): Models 25 Lead, 65, 65B, 252 Bass, 450, 400/112, 400/210, 720/115, 720/212, 720/410, 720K (keyboard), 750B (Bass) and 740P (PA). In some cases the second number marked the speaker configuration. http://www.univox.org/pics/amps/stage_720.jpg
  • Norlin launches a line-up of Lab Series amplifiers and the next year (1980) Lab 2 Series. These are designed by a small group of people from Moog (a division of Norlin). Norlin also releases entry level line-up named "Genesis". One of the co-designers in "Lab Series" team is Dan Pearce who later starts his own company "Pearce Amplifier Systems" that builds high quality transistor amplifiers (i.e. G1 and G2R). See later section of this thread for further details. http://www.moogce.com/images/lab1.gif

The 80's and 90's:

  • This is the real dawn of tube pre - SS power amp -style hybrids. Products like "Legend" amplifiers or Lab Gruppen's "AXE Amp" are preferred by artists such Johnny Winter or ZZ Top.
  • Westbury amplifiers (ca. 1980 - 1982): Westbury was the company that manufactured the late Univox SS amplifier models for the Unicord company. Essentially, Westbury amplifiers just "replaced" the Unicord "Stage" amplifier line-up of the late 70's. Models were W250 Lead, W255/110, W250/115, W550 Lead, W555 Bass, W1000 Lead, W1000-M "Mini-Lead", W1000-MF "Mini-Lead" with Fane speaker, W1005, W1005 Bass and Model 1000 Dual-Voiced Reverb Twin. http://www.univox.org/pics/amps/westbury_amp.jpg
  • TUSC "programmable tube amplifiers" (ca. 1981): These were hybrids that had a tube-based power amplifier stage. The interesting thing is that these were likely the first guitar amplifiers with DSP-based preamplifier that was able to store knob positions to switchable patches.
  • Rivera amplifiers: During his career Paul Rivera has done design work for Fender - and not only with tube gear: Transistor amplifiers like Yale, Montreaux and Studio Lead are some of his designs. Rivera has also designed amplifiers for Yamaha (G-100) and Pignose.
  • The dawn of various "tube emulation" circuits introduced by designers such as John Murphy (Carvin), Eric Pritchard (PRS & Pritchard), Sondermeyer (Peavey).
  • Early modelling and DSP amplifiers. Information?
  • Tom Scholz introduces the Walk-man inspired "Rockman" headphone guitar amplifier in 1982.
  • Tech21 introduces SansAmp in 189.

Note: Plenty of the stuff presented above is based on hearsay or to history presented by companies so its accuracy is highly questioned. For example, many companies like to claim they did or invented something first. In most cases this is far from the truth. Please doublecheck all the contributed information (oe at least try to).

I have tried to keep up a detailed list of amp manufacturers up to early 1970's. I consider these companies as sort of "pioneers". In circa 1968 many application notes describing efficient and moderately inexpensive amplifier circuits were released to boost up sales of new transistor models. This caused the amount of SS amplifier manufacturers to skyrocket. Past this point it is pretty difficult to keep any track of the various companies.


The initial post seemed to be growing quite large so I split it... Anyway, in case there are people who are interested in this topic  - and who haven't noticed the updates - here is a chance to catch up.

Extra insights to history (and things I need more information on):

  • Of course more details to above. Specific lists of amplifier model line-ups and their designers plus innovative features etc.
  • Randall, Roland, Ampeg, Marshall, Vox and other famous brands.
  • Benson, Gretsch, Ibanez, Maine, Selmer, Traynor?
  • H&H. (Harrison & Hill) Also known as H&H Acoustics and H&H Electronics. This was a British company that made some fine SS amplifiers (both PA and guitar) in the 70's and early 80's. Likely these are known best from Van Halen's setup where a MOSFET H&H was used to drive the speaker cabinets. Some H&H amplifiers also had green, glowing faceplates which were actually electro-luminescent panels. In 80's the company bankrupted due to failed attempt to develop a "music computer" and was sold to Carlsbro.
  • Baldwin (and Burns). Another forgotten legend. This old British company originally made piano's, keyboards and keyboard amplifiers. In the early 60's the company decided to expand on to guitar business and tried to buy Fender. However, they lost bidding to CBS and bought facilities from Burns. In 1965 Baldwin started selling guitars and amplifiers manufactured by Burns under its own brand name. At first the models had only different nameplates but in the late 60's the entire lineup of Burns models had been completely changed. Amplifiers were produced in Fayetteville organ plant supervised by Stan Krueger. The Baldwin's response to Vox Super Beatle - The Exterminator amplifier (ca. 1967) - is a classic: 100W 2x15", 2x12", 2x7" in a single cabinet. In 1968 Baldwin dropped out from guitar business but continued with amplifiers buying both Sunn and Kustom in 1979. http://www.vintageguitar.com/brands/details.asp?ID=111
  • Jordan. There is amazingly little info about these amplifiers considering that they were quite famous in the 60's and were widely used by most "big name" acts like The Mamas and The Papas, Yardbirds and The Doors. Mostly this was explained by the fact that Jordans were the loudest equipment available at the time - even louder than the tube Marshalls. The Jordan amplifiers (and pedals) were supposedly manufactured between 1966 - 197x after which the company was disbanded and most of the technical crew including George Cole (the owner) and Bob Garcia (chief engineer) went to work for Rickenbacker.
  • Triumph amplifiers. These are quite forgotten amps from the late 60's as well. Since Triumph designed and built amplifiers for Vox (i.e. AC-50, and Vox 7 -and 4-series) it is not surprising that many features of Trimphs and Voxes were pretty similar. However, when Triumph-made Vox amplifiers were either all-tube or hybrids most Triumphs were solid-state.
  • Japanese amplifiers. Roland? Teisco? Yamaha? The latter had a famous (or infamous) "flat panel" TA-series in the sixties. (The amplifiers were shaped like pyramids see: http://www.geocities.jp/a104gs/yamaha.ta-30.jpg) Some of the Styrofoam flat panel speaker technology even found it's way to Fender Bantam Bass and of course was used in Yamaha keyboard amplifiers.
  • Gibson. The company designed some very early solid-state amplifiers and some of them were pretty good i.e. GSS-100 and "Les Paul" stack (LP-1 pre & LP-2 active speaker cabinet with 4x12" plus 2x10" horns). As a side note, if you happen to get access to LP-1 schematic read the design notes for a good laugh.
  • Sears owned various brands including Danelectro, Silvertone, Garnet, Prince, National, Harmony, Kay and Teisco. Amplifiers from Sears were mainly entry-level models and manufactured by numerous companies. It was typical for these companies to work for each other too. For example, Danelectro manufactured amplifiers for Silvertone. Similarly to so many other brands, the solid-state line-ups were introduced in the late 60's. Catalogue entries of first Silvertone SS amplifiers I've seen so far date to 1966. Most recognizable pieces of Harmony amplifiers are likely the "rally stripe series", which sported vertical, red stripes in the grille clothes. They (likely) came in a bit later. After the early 70's the Sears solid-state line-up had already seized to exist. Also, there were "mystery" amplifiers that likely were not part of the "Sears line-up": For example, Panasonic manufactured small power amplifiers for National and Princeton. (And assumably for Silvertone as well). These amplifiers shared identical cosmetics and were made in the late 60's or early 70's.
  • Some might remember Powersonic amplifiers with their flashing "light bolt" light bulb current limiter speaker protection. Any info on these?
  • Tel Ray. This Californian company made plenty of special tape-less echo effect units based on "Adineko Memory System" technology - also known as "oil can delay". The inventions of the company also found their ways to some Gibson and Fender amplifiers. The company had its own series of SS amplifers in the 60's called "Supernova". http://www.geocities.com/tel_ray/supernova.html
  • Premier amps. Again from the late 60's. Most recognizable manufacturer of these was Multivox. Earliest references to all-solid-state models I've seen so relate to model 5530 from 1967.
  • Canadian amplifiers. As usual, the transistor amplifier history is a big mess of various companies working for each other. SS amplifiers have at least been made by Wort (Walter Romanyshyn) and Ahed Canada for Sears. Garnet also manufactured amplifiers for Sears but as far as I know these were not solid-state.
  • Other famous brands that do not exist anymore i.e. AMP, GMT.
  • Lab Series. These are not Gibson amplifiers. Lab Series were manufactured and designed by Moog, which at the time was owned by Norlin - a company that also owned Gibson. Norlin used Moog's resources to release Lab Series in a response to Gibson seizing its amplifier production. Gibson did handle the distribution of these amplifiers though. The series included guitar amplifiers L3 (60W combo), L5 (100W combo Model 308A), L7 (100W combo Model 309A), L9 (100W combo Model 312A) and L11 (200W head Model 313A + 2 cabinets), which were all (except the L3) based on the same circuit but used a different speaker configuration. The higher power head model L11 also had a fan, beefier output transistor configuration and different power amplifier with higher VA rating and secondary voltages. Other Lab Series models were bass amplifiers L2 (100W head), L4 (200W head Model 317A) and L6 (100W combo) - plus keyboard amplifier K5. Very likely all of the amplifiers (except the low power L3) were using the same power amplifier module (with slight modifications) but a different set of preamp modules. I haven't seen any references to models L8 and L10; I'm quite sure that they don't even exist. The service manual of the series states that it lists all models from L2 to L11 so there is no model L1 either. I haven't seen any references to other "K"-series keyboard amplifiers than K5, so likely it was the only one of them. Lab 2 Series models were completely different from L and K models of series 1. These included B79, B120, GA60R-10, GA60R piggyback, GA60R-12, GA120R-10 and GA12R-12. Additional information is highly appreciated.


i have 2 jordan amps
1) from about 1969/1970 is a one 21 reverb 1X15 combo lists 125 watts but more like 50
2) from about 1987, korean made reverb 15, which is rated at 50 watts but more like 20

i've also seen a j120 bass master combo

i've also managed to grab pics of several different models i've seen online.


you wouldn't know who would have a schematic for a univox model 65??? mine has three input jacks, 5 knobs (volume, CLIPPING, bass, treble, and reverb). 2 footswitch jacks in back. board has 12 transistors while  what looks to be 2 power transistors(or mosfets?) off board???? some people call them  model U65RD, but it only says model 65 on back! the mother board has model S-65! thank you ! AXE


No, I don't know. The guy who made Univox.org page might have it, there's also a forum on that site where you could enquire. Unicord manufactured the Univox amps under brand name "Honey" in Japan. I didn't find any more info about those, however - even less schematics.

The best bet with any old amp is to trace the schematic yourself (or the parts of it that you're focusing on). It's a few hour job but you can easily spend days in searching the schematic from Internet – and still with a good chance of having no luck. If you find one there's another good chance that the "same" amplifier has gone through various revisions and the circuit you have under work is not really very close to schematic you found. In other words, you still have to trace down the schematic (at least partially) to be sure that you are fixing things correctly.

Univox.org has a schematic of U-65RN, which is obviously quite different circuit than the one in your amp but it can be partially very close. I've seen the PC boards of that amp and they are made in such way that the schematic should be very easy to trace down. Likely your amp is no different. Musicparts.com lists schematics of U-65R and U-65RN so the other one of them might be what you're looking for. I wouldn't trust that source, though; my limited experience from that company is not very good. Then again, I have a faint memory that "U-65" was released as both transistor and tube amp.

Like I said, you better just trace the schematic yourself and have it 100% accurate. After that you can share it to help other people like you.


the u65rn has some major differances from the s-65 or the mislabeled u65rd! the transistors are samsung or sanyo, i have no way of telling but, so i was told long ago. the problem is trying to find what is "base", "emitter", and "collector" on the originals, with out a schematic i am lost. cross reference i can tell if there "pnp" or "npn" but, when buying a replacement transistor you could put it in the same way as the original and the base collector and emmiter may be in a different order than the originals!? and they cross 2 original, with 2 diff. numbers pnp's with the same number!? i believe the differance in the 2 originals was mainly how the E.B.C. were arranged(what order).the problem is with mine is half the transistors are gone(not there anymore). and the half of the remainder have been traded out.
so it would be difficult to make a schematic. this is the reason why i need one, and also i have no voltage measurements to go by!?
the u65rn schematic i can use as referance but, the transistors and cap and resistor values are quite different.
i would be glad to make a schematic if i ever could possibly get mine fixed but, what the original voltage values are, and what the original transitors were, idk?????????(only about half the transistors i know from my own personal writings from over 10 years ago i found)

oh, and i would like to add that i have tried the univox forums, with no luck at all. and i am very surprised that after all these years there is no schematic or anybody had ever made one!? i have run into people that are in need of the same schematic and thats about it!?


OK, i started on the schematic!? i am using "express sch" and i find it difficult to use mainly from the poor symbols and trying to find the correct ones!? any easier freebee's? let me know?
it will take some time but, i will putter with it a little while each day when i can. it will be two page schematic (at least), because i am trying to lay it out how it is already in the amp!
i have the power supply part done so far!
I will be needing help, and i surely need to know the 14 transistors numbers and if possible the company who made them!?
i will leave all blank for now until i get that information!?
if i can finnaly fix amp i will take voltage measurements!?
can anybody help with the transistor numbers!??
thank you! AXE


i find some amps were marked or labeled with U65RD, and later the univox logo was gone and a "stage" logo was added in the upper left front of the speaker cloth. i also read that the place in tokyo japan had burned down. and westbury amps were produced in Korea? how true that is i dont know!?


the later "STAGE" 65 amp is way differant than the ealier U65RD! they have a "bright switch" instead of "clipping". it may just be a model 65B that i have seen!!


And a little more info on the date of Lab Series. I know for certain I bought my L5 before 1979. I have pictures of myself with it in 1978 - I'm fairly certain I bought it in 1977. (I graduated High School in `78, and played my senior year in the "jazz band" with this amp. The school year started in 1977). This was my first real amp (before that I played through a heathkit hifi amp with an orange radio shack speaker!). Gibson Labs also says it was released in '79, but that may be when they started advertising it (I remember an ad campaign with Les Paul). BTW, Still have it Still love it!! Never had a repair!


Thanks for the info Peter, I have to dig further on that topic.

Meanwhile, here are few links that might interest all those who are interested in guitar amplifier history.

History of Yorkville Sound (Traynor & Sonax)
(Well written and extensive article about the history of this company.)

Vintage Randall 1970 to 1990
(Scarce on content but has some nice pictures and some technical literature.)

Rockman: The Story (by Tom Scholz)
(Article about the history of Scholz Research & Development SR&D.)


I too bought a Lab Series L5 earlier than 1979.  As I recall, it was '77.  I will try to confirm this and get back to this forum.

I have compared the L5 to my 1971 Fender Twin Reverb in terms of sound and circuits. It sounds remarkably like a Twin Reverb in side by side comparison, but provides a little more note separation and clarity. The Normal channel of the L5 is a clone of the Fender Twin Reverb in many ways.  The tone stack has the same corner points, but is designed to work at lower impedance to match opamps instead of tubes, so the R and C values differ.  I have rigged the reverb tank to run off of the Normal channel, and in this configuration, the amp excels at doing the surf music & twang thing.

The Limiter control seems to emulate the tendency of Fender BF and early SF amps to hit the wall when cranked past 4 or 5.  The distortion circuitry in the L5, which comes into play if you crank the volume but reduce the master volume, seems to be an attempt to emulate the 12AX7 / 7025 preamp distortion that you can get if you dime some of the old Fender, but of course it sounds a bit harsh and "solid state" compared to the real thing.

By the way, you can get a reasonable bluesy sound by setting the controls so that the amp just begins to distort when the limiter engages, although this takes quite a bit of tweaking.

The Reverb channel on the L5 is another story.  I'm not sure what the designers were going for here.  With the Mid control at "0" and the Multifilter at "0", the treble does not provide very much brightness.  You have to add Multifilter to get the amp into brighter territory.  The sound with the Multifilter turned up is interesting and different, but not particularly my cup of tea for most songs.  I think the Multifilter is either an attempt to make a solid body guitar sound "woody" like an acoustic or archtop, or else it is an attempt to emulate the standing wave nodes and sound of a 4 x 12 cabinet as in Marshall.  It would be interesting to get some info from the original designers about the design philosophy behind the Reverb channel.

I know a guy that distributed Lab Series amps in the late 70s, and will contact him and ask him whether he can provide some more insight on these amps.


Exellent post ylo! This kind of info and opinions of  certain brand of amplifiers is most interesting.

mad hatter

AMPEG SS series of amps was introduced at the 1987 NAMM, the first NAMM after St. Louis Music bought Ampeg.  These amps weren't some sideshow or designed to be beginner budget amps.  The SS series of guitar and bass amps were the showcase of their display (in addition to the SVT) and were how St. Louis Music wanted to reintroduce Ampeg to the music market.

I have a 1989 Ampeg catalog and in it they describe the SS series of guitar amps as:
"The Ampeg SS Series amplifiers are to the lead guitarist what the SVT is to the player - Awesome"

That's how strongly the felt about the SS guitar amps.  These things weren't some bullshit joke "beginner" amps like some solid state amps are.  They were designed to be the "SVT" of guitar amps.
I think that the Ss series of guitar amps definitely lives up to that expectation

Ampeg SS-series 1987-1991.
Ampeg VH series 1991-1998.


My dad was actually the national sales and promotions manager for Jordan Amplifiers. He's got quite a few stories to tell about the various bands that used their amplifiers and some of the horror stories of equipment failures and other Jordan history.