Mark Knopfler Guitar Site

I recently saw this extremely rare amp offered on ebay  – a 1974 Musitek combo amp that looks very similar to the “Dire Straits” amp – the Music Man 130 HD 212.

In fact Musitek was one of the names  under which the very first amps were produced before the company was renamed to Music Man (see this article for more info on Music Man amps). As this was the first and only time I have ever seen such an early model, I want to feature it with this article.

The overall control layout was already identical to the later Music Man amp. The only difference I can see is a rotary switch with the positions ‘Off – Low – Normal – High’ at the position where normally the power switch is located. The later switch also allows  a low and high power position, but not the third ‘Normal’ mode.

The rear panel looks very different from the Music Man version – almost like a  self-labelled prototype (which possibly is the case here – or there was originally a proper panel which is missing on the pictured amp).

The 12AX7 phase inverter tube and the Accutronics reverb tank seems to be the same as they were later. Note that the Celestion speaker is not original. The other one is a 1974 Alnico speaker by Eminence, however with a smaller magnet than the model used in the Music Man.

Mark Knopfler started to play Music Man amps around September 1978. These amps were used for all live gigs from then on until the end of the Making Movies On Location tour in 1981. The Music Man amp was used on some studio recordings from this era, probably also on Making Movies, but it was most likely not used on the first album, and neither on Communiqué (here amps borrowed by Robert Palmer, probably Fenders, were used).

This amp shares many features of a Fender Twin Reverb, e.g. the same control layout, the same effects, a similar size, a similar look. It is surely fair to say that it was Music Man`s version of the Twin Reverb, although the sound is different.

HD stands for heavy Duty, 130 for 130 Watts from four 6CA7 tubes (could be switched to low power), and 212 for  two 12″-Speakers.

Some general info on Music Man guitar amps can be found in one of the last articles.

Controls

The HD 130 212 has two independent, non switchable channels, just like the vintage blackface or silverface Twin Reverb. Originally the two-channel design allowed to plug in two guitars so that two players could share one amp on a little stage – something that did not really make much sense and was hardly used, except the band could only afford one amp. Both channels have two input jacks (labelled 1 and 2), with 2 being less sensitive so that high gain instruments (e.g. keyboards) could be plugged in without distorting the first gain stage (which is pre the volume pot so that reducing volume does not help in case of being overdriven with a too loud signal). Next to the input we find a Bright switch that works similar to the one on Fender amps: a small capacitor partially overrides the volume poti with the effect that the more treble is boosted the lower the volume poti is set – at almost 10 the switch has zero effect while at 1 it is strongest. Next is the Volume control, and three tone controls (Treble, Mid, Bass). The whole circuit looks identical to a Twin Reverb, but internally the values of the tone capacitors and resistors are different. The treble end is works at a lower frequency range than on the Twin so the sound is a bit fatter with a peak in the high mids. The midrange poti is also more effective than on Fender amps. All Music Man amps also feature a Deep switch that boosts bass frequencies. As this switch works between the pre and poweramp section, it is affective for both channels (the later models of the RD/RP series also have a bright and deep switch but these work and sound completely different).

The second channel additionally features a Reverb control and a tremolo with a speed and intensity control. The reverb comes from an Accutronics reverbtank of the same size as in the Twin reverb. Nevertheless the reberb sound is different, less dense and a bit brighter which is intended by the circuit design. The tremolo also sounds different than on a Fender amp. If you set the Intensity control to more than approximately  3, a second harmonic modulation is gradually added.

Sound

As said, the Music Man sounds different than the Fender amps of its time. The sound is a bit more nasal, with more midrange available. As the pre amp is a solid state design, some typical transistor distortion is gradually added when tyou crank up the amp. For this reason they were better suited for clean guitar sounds, and soon became a standard for country players. However, the transistor distortion does not sound that bad and is helpful to add some grit for clean sounds. The tube power amp section adds a typical warmth that solid state amps normally lack  off. Listen to any Dire Straits live recordings from this time and you will get the idea.

With 130 watts through two 212 speakers the amp is extremely loud, maybe one of the reasons Knopfler changed from the Twin to the Music Man when the stages became bigger.

Tube driver or solid-state driver?

The first Music Man amps (up to ca. 1977) had an additional 12AX7 pre amp tube for the phase inverter section. This tube and the corresponding hand-wired board were replaced with a new soild state circuit board that was said to be more reliable (with the old design a total failure plus the destruction of the expensive output transformer was possible in case of a certain malfunction scenario – however nothing you should really worry about if you own an amp from this time). Generally the tube vesrion is said to sound warmer, although I feel both sound nice and and not too different.

It cannot be answered with absolute certainty whether the one that MK used had the 12AX7 tube driver (like all amps before 1977) or not.

Generally in the first series (with the tube) the power switch was at the front panel of the amp and the stand-bye switch at the back. The power switch was labelled with “Hi – Off – Lo” (in the down position it was switched to about only 65 Watts).

The later series had the stand-bye switch at the front, labelled with “Hi – Stand-bye – Lo”. On a few concert pictures you can clearly  see that MK`s amp had the “High – Off – Lo” labelling (and thus might be the model with driver tube), however, I meanwhile have seen a few transition amps that still had the “Hi – Off – Lo” labelling but already the solid-state driver stage. What makes it more difficult is the fact that around the time of the introduction of the solid-state driver version, Music Man called back earlier amps from the dealers to change them to solid-state as well. Also, it was offered as a free service to convert amps with the tube driver to solid-state.

There`s one picture available from the Making Movies tour book that shows the back of MK`s amp. It is almost impossible to see any details, but a slight light reflection (of the aluminium tube cover) might be just at the position of the additional tube. All in all, I admit there is not much more than some speculation on this question.

Speakers

This amp can be seen first with Dire Straits on the Chorus TV 1978 video (a concert from October 14, 1987 in Paris).  There are a few shots that show the amp from its back side. Unfortunately it is not possible to tell from these pictures which speaker is inside with certainty.

The first amps had Eminence speakers with square alnico magnets, but I have seen models with a different Eminence speaker type that has square magnets of different size and shape (picture below). Then – about 1980 – the amp came with Eminence speakers with round ceramic magnets. Furthermore, the amp was optionally available with Electro Voice EVM 12L speakers – the same speakers that Mark Knopfler prefered in later years, e.g. in his Marshall cabinets. These Electro voice speakers normally had a huge golden magnet, but the OEM version in Music Man amps often had black magnets (picture below).

The second HD 130

Starting around the time of the US tour in early 1979 (March/April), MK used two of these amps. From summer 1979 one of them was to be equipped with speakers with aluminium dust caps (instead of the normal black paper caps), something that can easily be spotted through the amp grill on pictures of this time. The most famous speakers with aluminium caps was the JBL D120F that was optionally available in some n Fender amps (including the Twin Reverb). In fact, a Twin Reverb with JBLs has for a long time been something like the industry standard for ultra-clean sounds.
There are chances that Knopfler used JBLs as well, although I meanwhile tend to believe that the dust caps in his amps were a bit smaller than on JBLs. Many other speaker maufacturers had them as well, e.g. on the speakers in the Roland Jazz Chorus, or the Black Widow speakers that were installed in David Knopfler`s Peavey Deuce amp on the same tour.

Speakers with aluminium dust caps have a harsher sound with more treble than a conventional speaker. This can easily be heard on all live recordings from the second half of 1979.

The “Clapton mod”

The most prominent endorser for Music Man amps in the 70ies was surely Eric Clapton, who played two HD 130 heads with 4 speaker cabinets (with two 12″ JBL speakers in each, probably D120F or K120). Clapton`s amps were modified by the Music Man company. This modification included a different circuit for the bright switch, more gain, and a pre-amp out and power-amp in. Music Man service dealers or distributors were sent an installtion instruction for this mod, so it is theoretically possible that Knopfler had it as well.

It is unclear why Knopfler started to have two of these amps on stage. One possibility was to have a spare amp in case the first one breaks down, or he played both simultaneously to have more power, or – with a total of  four speakers – to hear the amps better from different spots on stage. I prefer to think that both were active (e.g. because both seem to be in use on rehearsals like in the BBC Arena documentary from 1980).

However, it seems that none of the input jacks at the front panel of the second amp was connected (an argument for the spare amp version), or this indicates that the amps had those pre-amp outs and power-amp ins to connect them from the back side (like Clapton did), an argument for the Clapton mod on Knopfler`s amps.

While the more-gain option of this mod does not change the clean sound, the bright switch works completely different with the Clapton mod, more like on later Music Man amps. It is much sharper, but less brittle. In addition, it is always effective, no matter of the volume knob position, while the standard bright switch is the more efficient, the lower the volume position is.

The same Music man amps were used on the Making Movies tour in 1981, driving closed Marshall 4 x 12″ cabinets. They reappeared on the Nelson Mandela birthday concert, Wembley Stadium, 1988.

The history of the Music Man company began about 1971 when Tom Walker, Forrest White and Leo Fender started a company called Tri-Sonic. Walker and White had worked for Fender before. Leo Fender himself had to sign a 10 years non-compete contract  when he sold his company Fender Musical Instruments to the CBS Corporation  in 1965, so he remained in the background until 1975.

In 1974 the company name was changed to Music Man, and in 1975 Leo Fender was named as its president.

Music Man started their amp line in 1974. It is not absolutely clear in how far Leo Fender was involved with the design of these amps, most sources say that alone Tom Walker was responsible for the amps, while Leo Fender designed the guitars and bass guitars.

The first Music Man amp – a head called Sixty-five – had already most  features of all later models.  In very short, these are:

• A hybrid design with a tube output section and a solid-state pre-amp section
• Overall look and control layout similar to Fender amps

The hybrid design – Get that Fender sound with a solid-state design

Fender amps were basically built for a clean sound. The distortion that is created when a tube amp is overdriven was something invented by creative musicians or by chance when musicians tried to get as much volume out of their amps as possible. Fender didn`t  focus on the distorted sound, in the contrary, they even tried to avoid it. In the mid-seventies , the famous Fender Twin Reverb even  made use of some tricks often found in HIFI amps to reduce as much distortion as possible (the so-called ultra-linear circuit).

It is surely fair to say that  Music Man followed the footsteps of earlier Fender amps, so their amps were also aimed at the best possible clean sound. So it is not a big surprise that they used a solid-state design (ICs and transistors) for the pre-amp section. Solid -state requires lower voltage and less energy and thus causes less heat. For this reason it was considered as more reliable than tubes.

The whole pre-amp section is mounted on a printed circuit board, while Fender amps still used point-to-point wiring for their amps at this time.

Tube power for warmth

The output section of the first Music Man amps used  6CA7 power tubes. A tube output section adds a certain warmth and subtle distortion to the clean sound. This is the opposite approach to the more modern approach of using a tube pre-amp with a heavy-duty solid-state power amp, a setup more suited for that singing, high-gain distortion.

The 6CA7 tube is pin-compatible with the EL34,  the tube that was made famous by Marshall amps, while Fender amps mostly used 6L6 tubes (or 6V6 for smaller amps). The 6CA7 can simply be replaced with EL34. As today hardly any tube manufacturer still produces the 6CA7, most Music Man amps meanwhile run on EL34s.

However, the circuit was rather different from Marshall. The power tubes in a Music Man amp operate at up to 700 volts at the plate. Fender or other tube amps – including Marshalls – normally have about 450 – 550 volts here.

About 1980 Music Man changed from 6CA7 to 6L6 tubes. Apparently this had not to do with tonal preference but with supply facilities at that time. Generally the amps kept their typical Music Man sound, no matter whether they had 6CA7/EL34 or 6L6.

The rectifier was solid-state (diodes) and not a tube rectifier like in many early Fender amps. A tube rectifier causes a drop in voltage during the moment the amp is driven to maximum output. Thus, the sound becomes softer, similar to a compressor. Solid-state rectifiers sounds punchier and slightly harder.

Originally there was one pre-amp tube – a 12AX7 – used for the phase  inverter stage of the amp. This is the stage between pre-amp and power amp. This way a certain amount of tube distortion was added. In about 1977 this tube was replaced with a solid-state version. The reason was that a certain malfunction of this tube could cause severe damage to the complete output section, including a damage to the power tubes and the expensive output transformer. The amps with the new solid-state phase inverter still sound very similar to the earlier models, but are nevertheless by some considered as sounding not as warm as before.

All Music Man amps can be switched to low power. This is not realized by switching off some of the power tubes like some other manuyfacturers do, but with a reduction of the voltages at which the power tubes run.

Music Man amps look very much like a typical Fender combo amp from the 60ies or 70ies. Like those black-face Fenders, they have a black control plate, a silver grill cloth to protect the speakers, and are covered with black tolex. The handle and the casters on some models are also very similar to Fender. Unlike Fenders, the Music Man amps never had those tilt-back legs that allow to tilt back the amp to adjust the speaker on the player`s ears instead on his knees.

Other features

All early Music Man amp models were 2-channel amps. The reverb and the tremolo effect affects the second channel only.

The reverb was based on a Acutronics reverb spring, similar to the one  in Fender amps. However, the reverb sound is different – thinner and brighter – than the extremely warm Fender reverb. This is rather due to the circuit design than to the spring itself. The tremolo effect is very effective, but also sounds different than on Fender amps.

The Music Man logos came in two versions: the original one was black on silver, while after 1980 it was silver on black. This way you can tell the older amps from later ones at first glance.

Most early Music Man amps had speaker made by Eminence, typically models with square alnico magnets. About 1980 they changed to round ceramic magnets, still produced by Eminence. However, some models with 10″ speakers always had ceramic magnets.

Other important players of that time who used Music Man were Eric Clapton, Johnny Winter or Albert Lee.

More information on Music Man amps can be found here. One of the next articles will cover the Mark Knopfler model, the 212 HD 130.