Machine Head: Repairing an old Hiwatt

Posted in Rock 'n' Roll at 2:35 pm by George Smith

The engineer leading the project that’s restoring the old Rolling Stones Mobile recording truck fixed my 33-year old Hiwatt amplifier!

Absolutely true! DD’s usual bad luck in place of no luck at all went on holiday. Serendipity took a hand and the warm light of good fortune shined down on the studio in Pasadena.

A month ago my Hiwatt Custom 50 suddenly died while I was doing a session with my friend Mark. It was pretty discouraging.

This Hiwatt’s a 33-year old amp, originally made in England, by a company that went out of business in 1984. I thought an appropriate repair, one that restored it to original factory standard sound and capability, would be hard to find in southern California. If not (there are a good number of rock and roll amp repairmen still here as a result of the glory days of the industry in Hollywood), it would be prohibitively expensive.

I assumed the worst case after some reading.

An aged electrolytic capacitor in the power section blows a spoke at then end of its natural life and takes out a few things downstream in the circuit, including the amp’s heavy iron, its output transformer.

Mark was not as downbeat.

His old mates from his decades old cover band were getting together for a yearly week-long session during which they rehearse for an upcoming high school reunion ball.

One of the friends was a fellow by the name of John Leimseider, an engineer employed at the National Music Centre in Calgary, Canada. And Leimseider, as described in the lead-off, is restoring the Rolling Stones Mobile which the center bought in 2001.

Guess the short version. The amplifier was quickly restored.

Pictures were taken to provide a record.

Interior of Hiwatt DR504 OL (1982) during repair. Full size.

Looking into the guts of the Hiwatt, it was immediately seen that one component was gone, burned off the lower circuit board in the upper pic. This was what was assumed to have caused the failure. Since the part was in scorched fragments, it was impossible to tell what it had been on visual inspection.

Using Mark Huss’ Internet Hiwatt resource site, it was found to be a power resistor. (The replacement part is the small white ceramic axially-wired block on the lower PCB in the above photo. You can identify it by the small black lettering codes. It is very obvious and the upper photo shows the chassis after the replacement was installed. But this is not the whole story.)

Upon further checking Leimseider determined one of the Hiwatt’s large power supply regulating electrolytic capacitors had failed upstream from the incinerated part on the PCB board. And this probably resulted in the immediate overload burn that cooked the component into pieces, a secondary effect.

The electrolytic capacitor that failed was the big blue can on the lower left in the above photo.

The parts took a couple days to source and the next picture shows the complete refurbishing.

Refurb/repair: Black cans, one lower left, two on the right.Full size.

The original large blue capacitors (three of them) were rated at 350V. This Hiwatt, I was told, runs at three hundred. Exact replacements could not be found and Leimseider found an electrolytic capacitor rated at 400V, one assumed to furnish more tolerance, a good match in quality.

Three were purchased and replaced the original failed cap as well as two similar ones on the right side of the Hiwatt’s chassis. The photo shows the result. Gone with the blue, in with the new black. The black cans, smaller in diameter than the originals, did not precisely fit the old adjustable mounting clamps on the chassis.

Wrap-around shims were used to help anchor them securely.

And all the potentiometers, the amp’s volume and tone knobs, were cleaned.

The work was fantastic! Even with the exclamation, that doesn’t quite do it justice.

On Wednesday I fired up the thing. The Hiwatt roared into life, its electrified British glory restored. Mark often told me it was the best amp he’d ever heard. Hyperbole, for sure, but it is, again.

It sounded better, in fact, than before it died. The replacement capacitors reduced the noise floor of the Hiwatt at idle.

I can’t reliably say how it was when at rest in 1984 but it was a remarkably quiet heavyweight guitar amp at high power. Over the years, as its electric sinews tired, it lost a little of that. Now it’s back in the neighborhood where it belongs.

Tech specs on the snap in can capacitor replacements: Three L.C.R. 220 microF 350V capacitors came out. The L.C.R’s were made in the UK in 1982, the same year as the amplifier. One, as described, had blown, although there was nothing visible on the exterior . The two others were OK.

They were replaced with three Kemet 220 microF 400V aluminum caps bought from Digikey. Price: $6.12/piece.

Considering the superlative sound of the Hiwatt after repair, I’d be disinclined to spend more for capacitors said to be more higher end than Kemets or anything similar. F&Ts, from Germany, seem to also be a favorite.

Additional notes

My Hiwatt, a DR504OL model, was made in Surbiton, a part of greater London, in 1982. Its badge shows it was made by the Biacrown operation.

The original creator of Hiwatt amplification was Dave Reeves. He fell down a staircase and died in 1981. While he was alive all Hiwatts were badged with his company’s name, Hylight Electronics.

When he died things started to fall apart. The employees of Hiwatt soldiered on as Biacrown and this is when my amplifier was made.

You’ll notice the signature “Harry Joyce” on the chassis.

Harry Joyce was the original expert wirer hired by Dave Reeves. His work was meticulous and virtually bullet-proof. Joyce became semi-famous in later years, specifically for his work wiring Hiwatts.

You can look at the photos and make your own calls. All the wiring connections are at neat and precise right angles. Braided wires are symmetric. There is no more or no less than the best fit wiring needed to make all visible connections.

The amplifier is a a hybrid of craftsman point-to-point wiring and two traced PCBs, populated with parts mounted using some of the same features from old electronic turret boards and strips. All the sockets for the Hiwatt’s pre-amp and output tubes are flush mounted and anchored to the chassis, separate from the PCBs.

Sidebar: Beware of concern trolls in vintage amp forums.

There will be someone who has just bought an old Hiwatt, either a Hylight Electronics or a Biacrown, and been thrilled to discover Harry Joyce’s signature on the internals.

Inevitably, a concern troll shows up to imply that Mr. Joyce maybe didn’t put that there. Another person working in the same room did. Yeah, sure.

Or that it is not a product of the Joyce wiring operation at all, a complete forgery. And that only the concern troll knows the proper parts of a bona fide Hiwatt and how it should be restored.

These people are trying to be f—-. Their opinions are purposely misleading trash.

I bought my Hiwatt in ’83 or ’84 from a small shop called Picker’s Delight in the Pennsy Dutch town of Emmaus. If as late as 1984, it was the year Biacrown Hiwatt was going under.

At the time, nobody wanted Hiwatts. The market was passing the company by. To be fair, market and changes in taste crushed other companies in the guitar amp business during the same period. Orange, another famous British amp company, went under even earlier. And Fender Musical Instruments almost died. (Actually, Fender was considered a clueless joke of a company when I bought the Biacrown Hiwatt.)

Today Orange has risen from the dead in a most remarkable way with a presence in show rooms all across the country. And Fender is once again almost at the very top of heap. But none are the same companies they were. In England, even Hiwatt is reborn.

But the early to mid-Eighties were nothing but a period of decline, especially for Hiwatt, ending in failure during the rise of hair and thrash metal. Everyone in the region was into Marshall JCMs and full stacks modified with extra gain stages and strange warping power tricks in the output section to copy the attack, density and style popularized by Eddie van Halen and his initially unique rig. (Never my thing, obviously, and not uncommon, I’ve found. Ask me about the times I was asked by visiting label guitarists how they regretted their faddy, modified Marshalls.)

Marshalls were higher gained amplifiers than Hiwatts, the latter which supply quite a lot of clean and loud headroom.

Reeves apparently saw the future coming, if imperfectly, and had redesigned his 504 models to have a little more extra saturation in their distortion through utilization of some extra unused capacity in the pre-amp tubes.

This resulted in the 504OL, of which mine was one.

Practically speaking, I didn’t notice and it didn’t matter. Mine was still really loud and clean when compared with any other similar big amps.

And that is the reputation of Hiwatts. Loud and fairly clean until the volume is turned up to scary levels. They force a technique in classic electric guitar rock upon you. A Hiwatt is unforgiving.

Play right or everyone in the room knows it.

But, if you want the big BRA-A-ANG, the element of sound Pete Townshend of the Who made famous on tours of America in the late-Sixties and Seventies, that’s the Hiwatt.

Or maybe you want to sound like Dave Gilmour of Pink Floyd, another big and very famous Hiwatt user. Face it, though, even with Hiwatts, you’re not going to sound like Dave Gilmour, ever.

In eastern PA, and as far north as Maine, to NYC, and and well into New Jersey, now in southern California, my Hiwatt went a long time before its seniority caught up with it, slightly.

Who, on hit records, used Hiwatts? Pink Floyd, the ‘Oo, Emerson, Lake & Palmer; Alvin Lee & Ten Years After, Procol Harum, Robin Trower, the Faces, the Rolling Stones at Hyde Park, the mighty Status Quo, Slade, Manfred Mann’s Earth Band, Jethro Tull, Rush, the Georgia Satellites …

Final notes

Picker’s Delight is long gone from Emmaus. Sadly, its owner died years ago.

I still have one sales slip from the place, the one for my Washburn guitar, written about here.

None of this write-up, indeed even the quick turn-around in the repair, would have been possible without the the web resource that is Mark Huss’ Hiwatt.Org. The picture of the DR504OL head at the top of the post is linked from it.

Wthout who and what not possible: John Leimseider, Mark and the Saturday night rock, roll and movie festival in Pasadena.

We all came out to Montreux
On the Lake Geneva shoreline
To make records with a mobile
We didn’t have much time …

We ended up at the Grand Hotel
It was empty cold and bare
But with the Rolling truck Stones thing just outside
Making our music there

Smoke On the Water from Machine Head, Deep Purple

1 Comment

  1. EZSmirkzz said,

    April 5, 2015 at 8:24 am

    Thanks for the informative and relaxing head cleaner sir. Never much of a player, but a helluva listener, it’s kind of cool to read stuff now that brings on a, so that’s how they did it moment.