My involvement with all this is fairly well known and needs just a short explanation. For the uninitiated, here it is again. Having been around the HH products since their inception I was invited by Lyndon Laney to look after the service, spares, information and back up of the "old" products when he (BLT) bought the HH Electronic company from Carlsbro in 1989. We also now OFFICIALLY look after the backup of obsolete and vintage HH, Laney, Tama, and Ibanez products.  

The following article is based on my own 45 years (limited) experience and involvement with HH, Laney, and also examination and repair of Marshall, Hiwatt, Vox, Fender, Mesa, Trace, Ashdown and other similar product made since 1967. It is written from a totally biased engineering point of view. All copyright is reserved and I would prefer you didn't use this text without prior permission. They might think I said it. Libel, Plagiarism etc. Ask first and I will almost certainly say YES.. Scratch me - I'll see you in court asshole....

The whole idea behind this document is for me to:
  1) Give the reader a brief insight as to how and why HH became involved in the music business in the first place  
2) Expound on the differences between the early "Music range" amplifiers and note their foibles.
3) Discuss the music range guitar amps as they are most interesting
4) Expunge on a few other cult HH products of the time
5) Mention briefly the less interesting (but still very good) old HH products made from 1983-89
6) Give apologies X I've given up apologising I'm too old

7) Have few beers whilst struggling with Dreamweaver and a new laptop keyboard. Windows 7? Isn't it just great?

Why they became involved
An engineer named Mike Harrison formed HH Electronic in 1968. His idea was to produce a professional solid state power amplifier suitable for broadcast use. He designed the now legendary TPA series amplifiers, many of which are still in use in studios all over the world. HH also won the coveted BBC contract to make the AM 8/12 amplifiers. But by 1970 HH was hungry for growth and looked to the consumer markets for feed. They decided the hifi market was too fickle but that the live music market held great possibilities. Harrison started from scratch to design and produce a range of guitar/bass/PA amplifiers that would sound good, stand electrical and mechanical abuse, be powerful and light in weight, and also incidentally decimate the then current solid state (and all other) musical opposition. So the "Music Range" (HH terminology and name) was born, and he succeeded somewhat.. What you also have to keep in mind is that while all this was going on in the 70's (and now seems very important to us) HH were busy supplying massive amounts of high end equipment to the lucrative broadcast, defence, aerospace and industrial markets. The Music range was just a small part of what they were doing at the time. Very well done..

The first music range products were the IC100/IC100S/MA100/MA100S/S130 and appeared around the end of 1971 - early1972. They were not copies or adaptions of any other product and were radical new designs. The IC100 was drawn up in June 1971, the IC100S in September 1971, and the MA100/S later in March 1972. I’m sure production was already in progress at these times. Early serial numbers had a pattern. 2 prefix was MA100, 3 prefix was IC100S, 4 prefix was IC100 (eg 2081 was MA100 build number 81, 4054 was IC100 build number 54 etc). Later serial numbers are quite meaningless and were applied across the whole HH range for sales records only.The VS Musician, VS Musician Reverb, and the VS Bassamp were drawn up around January 1976 and were available shortly after. The IC100L appeared in mid 1977 as a response to dealers who preferred the IC units to the new VS range. The MA150 and S150 appeared in the early 1980's and were the last of the Music Range products. The music range products are nowadays considered the most interesting and sought after items from HH so I will go on a bit in the next paragraph.

  You have to appreciate that when these amps came out in 1971/2 transistor pre and power amp technology was in its infancy especially in the new hard use world of the gigging music business. Like every other builder HH set about resolving these issues – but it took time. Their major problems were:
1. Op amps, noise and reliability. The HH preamplifiers were all based around the then quite new (to the audio industry) 741 operational amplifiers. Early units used 14 pin devices, later units 8 pin. These are ALL THE SAME DEVICE although there is confusion amongst the no engineering brain (but I have researched it on the Interweb..) assholes - as some were prefixed 2741, A741, shit741, pig741, concorde741, etc, and fostered no doubt by the fact that most HH diagrams including the ones I drew show 14 pin nomenclature. I had realised by as early as 1969 that these were ideal building blocks for audio but even the best ones were noisy, and also even though HH used Military spec devices in the early units, noise levels were high and failures were common. The early HH amps used +/-19 Volt supplies for these devices – I consider that ambitious even with today’s devices as reliability of op amps is loosely a function of the supply voltage. The reduction of the supply to first 16 Volts and then 15 Volts (by the time the VSM/VSB came along) paid dividends. The noise problem in the IC100/IC100s units was tackled simply by the provision of a Stage/Studio (gain reduction) switch. A better power supply layout in the VS units helped once again..
2. Power amplifier failure. This was a big problem. The first units I ever saw in 1971-2 used Darlington based output stages similar to the second series TPA 50D and had driver pcb numbers AO 3073, (and AO3073/2 - second attempt, getting there...) I dont think the transistor based TPA AO3071 was ever used in the music range. The Darlington units were state of the art and well designed but turned out to be totally inadequate from a gigging point of view. There is a slight difference between a TPA 50D being used sensibly by a qualified BBC engineer using a controlled signal source connected to a correct speaker load using impeccable cables and young son hammering a Les Paul or a Strat at full power+++ and then some through an IC100 or S connected to as many speakers as he can find (Impedance? Wosthat?) using dodgy bell wire speaker leads and sellotape wrapped arcing sparking shit jack plugs. That slight difference is that it bangs and costs money to repair and doesn't do your reputation as a manufacturer any good. Ah.. So they changed to using a conventional bipolar output stage (AO 3103 pcb, through issues 2/3/5/6) and the problems grew less, but still didn’t quite go away. I maintained then and still do that the problem was not the actual output devices themselves, but the driver stages. The driver transistor part of a typical Darlington output transistor is fabricated on chip to supply the theoretic need of the output transistor part – not big enough in our thrash music world. The discrete TO-5 drivers used on the AO3103/5/6 were better but still only just adequate. In December 1974 the AO3103/7 pcb with its two grunt overkill RCA 40871/2 plastic driver transistors appeared across the range and the problem was minimised. The AS00014 pcb used in the VS and later units was a further development of this, getting rid of all the TO-5 devices and inheriting more sophisticated short circuit protection courtesy of the S500-D (Crown). This was a great move has proved to be a very reliable design – we still make it as a replacement to this day. Oh in 1974 they added a “D” suffix to the serial numbers of the amps fitted with discrete driver stages.

  RE: Darlington output stages, In the mid-late 70’s I paid off a substantial part of my first mortgage with the proceeds I made from repairing another certain manufacturers range of (Darlington OP) "Solid State Lead and Bass" amps. NO names mentioned. Again libel etc.. (Not bad sounding amps though Jim - RIP fella..)  
The IC100 and IC100S

I still have Mike Harrisons original A0 pencil drawn circuit diagrams of the original IC100 and IC100S . First series IC units can be identified by the lack of the stage studio switch and AO3078/A front end (in the IC100S). Second series amps followed shortly after and had the Stage /Studio slide switch on the back panel, and the more familiar toroidal transformer and AS3078/B preamp. Early examples also had solid aluminium knobs with grubscrew fixings, the rear panel was fixed with Allen head set screws, and the pre amp Zeners were MZ (these look like a TO-92 transistor with 2 legs).The definitive version with the Stage/Studio switch in the centre of the front panel came I think at the end of 1972 and stayed cosmetically the same until discontinued in 1976. The power amplifiers were updated constantly. These amplifiers are quite noisy compared to modern stuff. Thats the way it was, thats why they fitted the Stage/Studio switch. Oh, and the S in IC100S meant Standard, not Sustain. See MA100S etc. (You cant tell me this was a PA amplifier with Sustain old chap. Get a life..)

!First series IC100S units had a totally different preamplifier, pcb 3078/A. This is essentially similar to the more common 3078/B used in the later units, but many component values were different and a transistor driven filter preceded the power amplifier stage. These amplifiers have a totally different sound to later issues.

If you are trying to emulate Mr Bolans sound, you'll have to consider this one.

Full details of other important differences/changes and how to date your IC100/IC100S/VSM/VSMR/VSB are given in our service manual M101.

  OPINION: The IC100S, with its simple passive tone controls, has one of the best rock and roll sounds of any solid state amp of the period. Early versions with the transistor filter are even better and more desirable if you can find one, having a great controlled response. I think this is what attracted Bolan and friends in the first place. The upmarket IC100, with its active tone networks, has a more lush sound - slightly more synthetic, but was loved by club bands for its versatility and power. Both amps in 212 combo form were seriously loud pieces of kit - large venues, no problem. I know, I was there, I used them....  
  NOTE If you ask for information by email etc note that ALL guitar combos including the later VS units carried the "212" badge. (This just means it has two 12" speakers in it. Nothing else. dumfek..) I need to know which MODEL it is to provide specific information or parts. If you are really stuck just tell me what the knob on the far left says/does. This tells me ALL I need to know. Thank you.  
Montage of front and back of HH IC100S 1st series amplifier - note NO Stage Studio switch front or rear. IEC socket is aftermarket addition. Serial number is 3083 ( 3 denotes IC100S, 083 is build number)
The VS Musician, VS Musician Reverb, and the VS Bassamp

The VS Musician, VS Musician Reverb, and the VS Bassamp were drawn up in January 1976. Early versions can be identified by having two input jacks on the main channel, in lieu of the single jack plus "Effects Input" DIN fitted on later units. These were a natural progression from the IC range, and demonstrated HH's response to the necessary "Valve Sound" then beng requested by certain factions. These amplifiers all contained a sealed "Tone Correction Module" aka the "Valve Sound Module" which was promoted as the heart of the Valve Sound of these units. Used correctly it actually worked very well. Used incorrectly by the set the controls for the heart of the sun brigade, the transistor power amplfier took over and the subltey was lost. The non reverb VS Musician was produced in small numbers and is now quite collectable. A reader points out, quite correctly, that the perspex panel on my first edition VSB pic above is different to the later issues. Spacings are the same, but a box is drawn round the bass boost control on later issues. We live and learn...

  OPINION: Although the passive EQ tones of the IC I00S are lost in these amps, used correctly the sound is very good, very 70's, and the VS function works very well. The VS Bassamp feeding a good 2 x 15 cab is an absolutely cracking bass sound.. Sorry folks, power and Sub FX is one thing, brilliant sound quality is another... It is also possible that the VS units were featured on Bolans last recordings as they must have been available to him (as an important endorsee and patron) before his untimely death in 1976.  
HH VS Bassamp (1st series), VS Musician, VS Musician Reverb
The VS Tone Correction Module - AS00015/A/B

The idea of the tone correction module and its contents was patented by HH, and a schematic diagram was never published by them. Nor will it be by us as we (truthfully) do not have one. We build replacement modules from an original pattern. And as it exists only as a replaceable module, a schematic diagram of the internals is unnecessary for servicing and repair purposes.

And thats why I'm here son... But for any interested geeks:

What I will tell you is that this module is not a complex holy grail integrated valve sound device. It actually contains six completely separate unrelated electronic mechanisms. They are:

1) The inductor and support electronics for the Middle control

2) The inductor and support electronics for the Presence control

3) The inductor and support electronics for the "Voice Switch" function

4) The harmonic generator for the "Valve Sound" function (the important bit, but actually a very simple junction FET stage)

5) The electronic FET switching necessary for the Valve sound switch/footswitch function (revolutionary in 1976)

6) Channel 1/2/reverb mixing stage (nothing works if this fails)

The AS00015/A is the VS Musician variant, the AS00015/B is the VS Bassamp variant. They are identical apart from two gain set resistors we fit when they are made.

Our replacements are not sealed, so you are quite welcome to buy one and draw it out if you are sufficiently interested...

The IC100L
  The IC100L appeared in mid 1977 as a response to HH main dealers who preferred the IC100/S to the VS range. In fact it was pretty much a failure, bearing no relation technically or otherwise to the original IC100. It just looked similar. In fact there were two versions of the IC100L athough they both look the same. First series units had so much gain and were so noisy even in 1977 (a clean sound with high output pickups was impossible) that HH issued a complicated gain DOWN fix, and the series two was born. Two op amps went missing and a lot of component changes from the original design - and the whole thing became calmer and more useable. Didnt sound any fickin' better though.  
  OPINION: Its your money. A lot of people like them.. Will last forever given care and a bucketful of spare TBA231 op amps...  
The Echo Units
  There were four types of echo unit made by HH as part of the music range. They were:  
  1) HH Echo Unit - This was tape based and had a single play head on a sliding bar.  
  2) HH Multi Echo - This was tape based and had four play heads selected by push buttons.  
  3) HH Digital Echo Unit - This was a rotary control analogue delay based on Bucket Brigade technology.  
  4) HH Digital Multi Echo - This was a push button control analogue delay based on Bucket Brigade technology.  

Early tape machines used a short tape loop similar to a Copicat (but not the same length..) and a simple jockey arm tensioning system. Very reliable in operation but tape life was short. Later machines had a much longer 3m. loop and a transport mechanism not unlike the Roland units. These can be recognised by the large perspex tape house you see when you remove the lid. All machines are capable of excellent performance, and are much sought after today. The later transport mechanism is crude but effective - given constant fiddling and maintenance.. These machines are NOT in any way to be considered "plug and play" - the top cover will be off more than it is on... You've bought a classic car, son... Get on with it.

  The "Digital" machines were "ANALOGUE" NOT digital and the performance and reliability were very poor. They were based on the now defunct Reticon BBD ics. Following many complaints from dealers and customers they were withdrawn after about 12 months production. There were so many official mods/fixes/change notes the mind boggled. The tape echos were regretfully not reintroduced.  

OPINION: Tape Echos - Superb performance if you can find a nice one and afford it. We have the spares and the tapes.

Digital Echos? - Fancy a second mother in law? Perhaps not. Thats what you might as well BUY.. And don't ask ME to fix it or set it up. Or "Calibrate/Tune" it (Another F stupid internet word...).

The MA100, MA100S, S130, MA150, S150

The MA100 and MA 100S (basic non reverb, that S again) although not considered very interesting now, probably accounted for the majority of early HH music range sales. A first class 5 channel 100 Watts+ PA with reverb, electroluminescent front panel - it had to sell, and it did. They sold SERIOUS numbers of these... Not overtly collectable but still a good working PA even now. And useful for guitarists with all the sounds in the floor pod. Note these amps are extremely noisy by todays standards - gain levels were set very high. Do the MA series (only) noise reduction mod detailed in the service manual. The MA150 was the later version, sported a switchable effects loop, and used a mains transformer borrowed from the Performer amplifier to provide the extra gruntitude. The S130/S150 were the power amplifier only versions.

  OPINION: These amplifiers are well suitable for guitar use when driven by a modern pod/FX processor, and are still very useable and reliable used as a small vocal PA.  
End of the Music Range
  Production of the guitar/bass amps was phased out around 1981 to make way for the new “Performer” range, but the MA 100 continued as the updated MA150 for several years.
A VS Musician Mk II was planned – I have the original unfinished works diagram and but it never made production. Strangely it also bore no resemblance to the impending Performer range amplifiers. They just changed direction overnight. Odd. Very odd.
What a mistake they made. (Perhaps they were all pissed?)
The S500-D

By late 1975 I was becoming very familiar with the Crown DC 300A power amplifiers that Slade had bought back from America following their first tour. These were to replace the ageing WEM power blocks which formed the basis of their PA. I noted the Crowns were virtually flawless in performance, and could deliver 340+ Watts/channel into 4 Ohm loads. Down side was that these units were 4U tall and about 9” deep, and they required forced rack ventilation – having no cooling mechanism of their own. The build quality was only fair. An internal mains fuseholder attached only by double sided stickytape? God. And like everything else they went WRONG. There was no load protection in the event of a catastrophic failure and DC on the output terminals… But they were the most powerful amps I had ever seen and they sounded superb and I was getting used to working on them...

In late 1975 for reasons I will not bore you with I personally handed a copy of the Crown DC 300A technical handbook (with schematics) to one of HH's senior representatives - he had explained to me that they were looking at producing a similar high power amplifier and any relevant data would be useful to them... (Didn't get me that free dinner though Clive did it..)

The S500-D was unveiled mid 1976. It was 2U high, 15” deep, had its own cooling system on board, looked mean, sounded perfect, green light front panel, and delivered believe it or not 340+ Watts/ channel into 4 Ohm loads. It could also work into 2.6 Ohm loads (3 x 8 Ohm speakers), delivering 440 Watts per channel. Wow. I took a great interest in these, even at that time. The driver pack was in the form of a potted block, apparently to stop people copying.. When they unsealed the driver module 12 months later, and published the circuit diagram I looked at this carefully and I really had to smile. This was no more than a straight copy of the DC300A but with minor changes to the output stage to make it quasi complementary. They even retained the American sourced 739 input op amp and high voltage driver stage with exactly the same resistor values! Dohh.. But what they had done – and this is creditable – they took the unworkable 4U Crown package and put it into a highly useable 2U format. The S500-D is a great amplifier. Not many people will work on these now. I do lots. BUT if it goes wrong it WILL destroy your speakers. There is NO load protection.

  OPINION: The S500-D has a quality of sound that is impossible to measure with test equipment . It just sounds so good...  
The V range. V150L/V200/V500/V800/M900

Arguably the most successful power amps in history, these were built around the then new Hitachi power mosfet output devices. Looking at the apparently simple drive stage, which I attributed at the time to HH, I noted that although there were some failures hardly any involved the output stages. Well done. And the performance was neutral and flawless, with overkill spec transformers and power supply components (13600uf/rail to start with, most later amps had 30000uF/rail. Great bottom end then...
It was only many years later that I was given a Hitachi Power Devices data book and realised that these designs were a straight application of the supplied data but with obvious HH embellishments. I still have the book. In fact, only problem with the Hitachi fets was the price – they were very expensive, even at the time. Wish they were still made now though dammit...

  OPINION: Great amps, flawless performance, messy complicated build. But a return to the 4U Crown type format AFTER the S500-D? And a fan that blows sideways? Did HH engineers not know that racks have closed SIDES? Dohh..  
The Performer Range - Super 60, Power Baby, Performer, Bass Baby, Bass Machine.

When these arrived for evaluation and comment on my bench as the replacements for the superb music range products, I opened them up expecting something else (in the words of Eddie Cochran). Not so, I was very disappointed. The build was again awkward, with a thick wiring umbilical between front and rear panels, and the whole build method appeared to be a backward step from the previous fine efforts. But they had used junction fets as building blocks, mixed with bipolar transistors and op amps, and had a mosfet output stage. They sounded very good, and the Bass Machine with its 250 Watts output was the most powerful Bass amp going. Great. But the input fets were gate unprotected, and they went down EVERYWHERE. By the time HH issued an official protection fix (A year later!) we’d been doing this anyway. These amps cosmetically strongly resembled the American Acoustic amps being imported at that time – with the pastel colour front panels - although they were electrically quite different. No disrespect to anyone but I don’t think HH should have been concerned at all, or chased this particular dragon – the Acoustic amps were good working stuff but blandly uninteresting and just about as unreliable as everything else of the period.

  OPINION: Actually very good sounding kit but heavy, complicated, awkward build, and not very reliable for the same reasons. And not yet very collectable. Cheap now. Difficult to mend/service cost effectively. Footswitch data see homepage.  
The Studio Series
  Studio 50 The earliest HH studio series amp, single channel with reverb 50 watt (darlington) op stage, 1 x 12" combo. Basic, good sounding, good build, bulletproof, heavy. If you see a head version on ebay, someone has chopped one up - they never made it as a head. Many were sold to schools/colleges - these are a dam good buy if offered.  
  Studio 30 and Studio 60 Guitar amps. Sold alongside the Performer range as a lower power, lower cost option (first time buyers?) They were actually very good sounding single channel combo's, and all had the high voltage FET input stages and Hitachi mosfet output stage, reverb and distortion etc.  
  Studio 60B Bass amp. Similar, with high voltage FET input stage and mosfet output stage. Compressor facility.  
  Studio 100 Guitar amp. Available as head or 212 combo, with reverb and distortion. One pc board design with preamp similar to the Performers but using transistor output stage similar to AS00014.  
  Bassamp 100 Bass amplifier, often confused with VS Bassamp. The front panel of this one does not light up green, again one pc board design with preamp similar to the Bass Machines but using transistor output stage similar to AS00014. Paramid EQ and (very good) opto compressor. Was available as head or combo.  
  IMPORTANT: In their infinite wisdom, HH emblazoned the Studio30/60 guitar combos with the "Power Baby" logo, The Studio 60B with the "Bass Baby" logo, the Studio 100 with the "Performer" logo, and the Bassamp100 with the "Bass Machine" logo. Dohhh. The confusion they greated between these Studio series amps and the Performer range is now ledgendary. Please be specific if you are asking for service information or advice. Its a real headache. Easiest way, if you think you have a have a "Performer" amp, for example, tell me if it is single channel or two channel with sound switch. That should do it...  
  OPINION: Studio 50 - Great basic 50 Watt combo. Studio 30/60/60B - Look a bit odd, but good sound, serviceable, well liked. Studio 100 - I know the combo looks like an old gas oven but was good sounding and powerful and has proved to be quite reliable. Bassamp 100 - ditto but trying to be a VS Bassamp, but good sound and reliable also.  
50 Series, 100 Series. L50, B50, K50, L100, B100, K100

These were being produced as HH passed into Carlsbro’s hands around 1982/83 and production continued into the late 1980’s. They were good working amplifiers based on traditional Carlsbro and HH values but were pretty unexciting products. Far cry from the original music range efforts. A couple of notes: The build quality was very good throughout, and whoever dreamed up the B100 got it smack on first time. What Bass player even now could want more sensible features than this, other than a sub harmonic dedicated owner. Dont ask - Its a quiz. Aspidistra etc. etc.

  OPINION: Unexciting but very good basic working gear. Versatile, good sounding. Will last forever with care. Yes we have all the parts...  
The Cabinets
  It is hard to imagine now, but until Carlsbro came along in 1983 HH NEVER had a woodwork department. All woodwork and cabinets were bought in from subcontractors. They were obviously the best available, most being made from a material called (at the time) "Taberpan". This was a very dense, hard, synthetic material. Nowadays I think we call it MDF. Ah. Great for sonic properties, wear rate medium, heavy - Oh yes, seriously Oh yes... And with those later big chunky corners, bulky too.. But they did the job well...  
  With the massive amount of interest being shown in all the old HH products I apologise if I have not mentioned your favourite or personal piece of kit. The range was so big and diverse, it is impossible to mention everything in a document such as this. I have therefore concentrated on the products that generate the most enquiries, and which I personally consider to be the most interesting. Guitar and Bass stuff usually..  
  I cannot finish this document without mentioning a few other great or quirky products that emerged from HH in the early days.  
  1) The HH Stage Lighting System. A reliable, well designed stage lighting system, that came with dimmer packs, cans, stands, and road cases. A great product, and many are still in use today. We have original spares.  
  2) The HH P73 electronic piano. A very good sounding analogue piano that ran under digital control. Great piano action keyboard. But complicated, VERY heavy, and sadly unreliable. I have a lot of parts, but dont ask me to fix it or tune it ( Eight oscillators and twelve notes in the scale...Hmm.). Not enough hours in the day as it is.. The planned RT-2 sequencer existed only as a pen drawing and was never produced. I have only one question about the P73. Why did they ever even consider this project to be viable, given what Roland, Yamaha and Korg were doing at the time?  
  3) The HH Monitor Amplifier and Monitor Extension Cabinet. No horn just a 12" twin cone loudspeaker. I found this disappointing at the time, but then someone noticed that these were the Monitors that didnt feed back given the slightest bit of gain. Hmm - Got that one right then.  
  4) The HH Stereo 8/12/16 mixers. Great period desks, excellent performance, reliable, serviceable. Official multicores were a ballache.  
  5) The HH MA200, MA400, and HH Communicator mixing desks. These were made in very small numbers in the early 80's, just before HH axed all mixer production at a stroke. They were well designed product, but considered too expensive to produce. I have spares if you can find one...  
  6) The HH SM200. The original powered mixing desk. At least this one is serviceable.. Well sort of.  

Schematics, footswitch data, fault finding hints, and more detailed dating info can be found in our SERVICE MANUALS which are available by email or CD rom if you prefer to pay extra for the postage.

Thats it for the moment - MA
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