Solton BV-60

Burns, Selmer, WEM, and more

Solton BV-60

Postby Morden on Mon Nov 19, 2007 11:41 pm

I have the opportunity to get this amp for pretty cheap. Anyone had experience with it?
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Re: Solton BV-60

Postby Racing on Wed Oct 19, 2016 12:17 am

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Holy thread revival batman!! But...yeah.
Picked one up recently.

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Before picking this one up i listened around a bit and what was told was...differing a bit. One thing´s for sure,sans a rear facia the amp is downright dangerous. Exposed mains entry as well as fuseholder as well as transformer solderjoints.

It arrived dead on arrival.

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As this is an early unit that brings the "low" cab and in turn point to point wiring.

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Rather roomy. That shield there is for the pots and what not.

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For a twin EL-34 amp the transformers are absolutely MASSIVE!
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Re: Solton BV-60

Postby Racing on Wed Oct 19, 2016 7:55 am

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Someone had been into this one previously. The first hit,standing,"can" e-lyte had been replaced with a F&T 50µF+50µF/450V jobbie.
What turned out to be an issue as THIS particular amp didn´t have multiple primary taps and thus was limited to 220VAC only. That made B+ soar and exceed that 450V of the F&T piece by a margin. B+,as it turned out,came to settle at rather specific 500V under load in its "old" guise.

Rest of them were these rather funky looking twin axial stockers in the pic.

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Paradise lost to a degree i presume cause one of them had gone to lunch. That one in the middle,check dead center of its black end and you´ll see how it have ruptured. Elvis had indeed left the building.

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Wash n rinse. Major amounts of dust,old nicotine and tar... That aside,that tracing there on both powertube sockets were reason for concern. In short..reason to question why.

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Sure enough a plural amount of components for the bias circuit was shot sky high and in doing so had made screen resistors and what not go belly up too.

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Amp held ONE old Wima cap. Guess what leaked like crazy? :lol: Again. Anything that old that says Wima or Hunts...bin time.
The golden colored Siemens ones were just fine tho.

So. Solton BV-60. A twin EL-34 amp that runs a concertina PI and that aside a three stage preamp job. That above done i took to fire the entire thing up and....we were in business.
While at it someone had replaced a few part "Mr Handyman" style before and..guess they hadn´t had component values correct. Just took notes and pushed on.
Now a BV-60 IS a bass amp. Make no mistake and as i had it producing sound....what it sound of? Well. A stocker does cleans rather well i´d say. Nothing to report home about but still.. Pushed tho,seing the DC coupled concertina and all,it sounded bloody awful! :shock:

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Mostly for SnG i came to challenge that. Installed a minor e-lyte across the 2nd stage cathode resistor and in turn installed a 1M gridstopper for the concertina and..way better when pushed. However the sweetspot "windows" were still pretty narrow.

Please be adviced that this is an early unit. From schems online and what not it seems the later ones were UL,in contrast.

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Operation clean-up then.
The bottom part of the chassis is bolted to the transformers that in turn holds this vertical piece of sheet aluminium (entire chassis is out of aluminium). Rather neat cause as you unbolt the lower "tray" the entire thing left becomes REAL easy to manhandle on the workbench.

One of the spots where Mr Handyman had been at it was the reostat installed trimpot for bias amount. Setup consists of one trimpot per above on the AC side of things and in turn a balance setup a´la FBT 500 et al to adjust between the actual powertubes. Well,seing the winding handing us approx 60VAC a 220k trimpot was out...as was a 100k as i tried it. Final value,as it turned out,was 22k.

What impressed me though was the sweep of the tonestack. Reminds a bit of Marshall/Fender ones then again not.... More on that later.

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As stated the pts within had seen better days. Old nicotine,tar and what not all over the place so a lot of alcohol and washing acetone was used. Then...came to debate the stock wiring gauges with myself and...replacement time. It´s on the REAL feeble side stock.
The solder supports came out of there as well,being riveted in place with sort of stand-off rivets stock. Most of them loose however...

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The entire bias setup was reset. A few e-caps installed extra where needed too. PI in turn was reset to a LTP,for better for worse,and caps as a general whole,seing it´s a point to point amp of sorts,were secured in place with a minor dab of glue each.

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I opted to separate grounds,within reason. That brings that anything signal was grounded separately,down to the various e-lytes across cathode resistors. Anything "power",appreciable power that is,by itself and in turn the actual preamp by itself.
Yep. Makes for a REAL silent amp in idle.

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That e-lyte down and right is a radial that i secured in place with a small bracket. Balance pot for heaters is stock. As you can see in turn the entire bias part of the amp was moved to the opposing solder support.

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At this point the amp was up and running again,from an electrical point of view. Choke i implemented is out of an old Philips and is of 4H.
Basically it all came to rest and what was ahead,apart from wiring for signal,was that i needed to adjust rail voltages a bit.

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Yep. Choke and what not.

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Yep. Up and running again,roaring its heart out. Now with way better results. Had a hum stemming from the EF-86 entry tube though.

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This OTOH impress me way less. Basically that there is exposed mains wiring,exposed solder joint upon the transformers and what not. Although it is all covered by a to be rear facia/plate i feel that it isn´t exactly up to snuff from an engineering POW. It IS unsafe...as people in general are friggin morons. In short an accident waiting to happen.

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Yes. An IEC jack and a fresh fuse holder. That and the stock sticker that tells what jack hands you what impedance. Wiring for the jacks being replaced as well.

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Up front i scrapped the one input jack and opted to install a pot there instead. Even managed to scavenge a fitting knob for it.

So? What it sound like?
Well,with the stock tonestack and pots...different. It sounds different. One of the pots is marked "presence" which is total and utter BS cause what it is is...a bright cap across the stock volume pot and done deal run by 1M lin pot.

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That´s what it´s SUPPOSED to look like out back. Believe i´ll abandon that idea tho for a more traditional sort of Marshall-y piece of cut to size wood. Then...them exposed solderjoints and what not..i do NOT like that one yota.

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Hum was on the agenda. Handled that by installing that there small metal shield vs the heater trimpot. Proximity to the g2 decoupling cap of the EF tube was simply to close. Have run into that issue before so i basically homed in on the issue right off the bat. End result,amp dead quiet in idle.

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Uhu. Stock tonecontrol. After having played around with the amp a bit i opted to reset a few values. "Slope" resistor comes LAST in this one,and i opted to replace the stock 220k resistor with a 470k trimpot in reostat form.
Then..some components were simply replaced. Real old ceramic caps for instance...no no no no...

As stated the amps tonal range and character is...different. That brings the Q is different is different as in good.?

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As the EL-34s are installed in horizontal i opted to add a couple of tube retainers. If nothing else as it FEELS way better.

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Tweak time then. A "discharge" resistor of 220k was added. Then..for the actual circuit. All in all it was left alone and i came to focus on rail voltages.
Settled on the LEAST voltage for the day.
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Re: Solton BV-60

Postby Racing on Wed Oct 19, 2016 7:32 pm

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Handed the cab some TLC and i´d say we´re coming full circle.

For those so inclined. These amps are rather plentiful around Europe,Germany specifically of course,and make for great platforms as they´re rather cheap to boot.
Granted,i picked this one up dead on arrival but at a rate of 116€. Kind of tells the entire story.
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Re: Solton BV-60

Postby Happy Face on Thu Oct 20, 2016 12:48 am

Damn, I wished you lived closer. Like on the other side of the Atlantic.
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Re: Solton BV-60

Postby Racing on Thu Oct 20, 2016 6:26 pm

Thank you.
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Re: Solton BV-60

Postby teenslain on Sun Apr 09, 2017 4:22 am

I've owned a GV60 for almost twenty years but only really been using it the last year... Blew the caps on it last year and Tim at Tym Guitars fixed her up for me, sounds absolutely crushing... I would buy another in a heartbeat if I got the opportunity... Here's mine...

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