Bogan Boutique Amplifiers

11/09/2026

So here's an interesting topic. I have a Jansen Bassman 5 Twenty five in - quite old, from 1964. Mostly original, except for the power filter capacitor replacements as far as I can see so far.

But interestingly, it doesn't have an impedance selector on the back. So there's only one output tap on the output transformer.

And the owner has asked me to determine the output impedance on the amplifier, as he hasn't plugged it in yet and wants to check that the amp is all good for his intended speaker.

There are two outputs for speaker on this amp. I assume they are wired in parallel, so it's either going to be an 8 ohm or 4 ohm output. The owner thinks it's 4 ohm. I'm not so sure so I'm going to test.

Stick around if you're interested in how you determine what the output impedance of an unknown output transformer is.

02/09/2026

So here's an amp you don't see too often any more. The good old Laney AOR Series II 100w amp. Perfect for stoner rock and all sorts of heavy rock and metal (especially if you like that 80s sound).

It's come in as it needs a decent service as it's not been serviced in forever. If you're interested in what it takes to get one of these back to gigging condition, read on, dear reader.

12/08/2026

Okay, it's been too long since I did a pictorial feature. So here's one of your old favourites. A Jansen Bassman 50. The first of the circuitboard ones. From about 1970 I guess. It doesn't have any of the hippie Christian symbols sharpied onto it so must be early 70s.

It's in a bit of a sad state. It suffered a power transformer meltdown a number of years back and got left.

Until the owner had the good sense to bring it to me and ask me to get it back into serviceable condition.

It arrived with the power transformer cut out of the amp, so I sent that off to the wonderful Brian Smith in Foxton for a rewind. In the meantime I set to resolving the problems with 50 year old capacitors that had been stressed out by age and power transformer shenanigans.

Hold on a tick while I load up all the pics for this one. I'll go through what you have to do to replace a power transformer in one of these, a full recap of the power filter capacitors, and testing when you get it all back together.

28/07/2026

Here's one you don't see too often. The mighty Red Bear, from Russia.

Turned up with the complaint "doesn't go", so could have been anything.

I plugged in it to test and it made the most awful humming noise. I was worried that the power filter caps might have gone, as these use weird bolt in caps that are hard to source, and I didn't fancy rebuilding the amp with Western-style caps.

Well, it turned out to be simpler than that. One of the power tubes had shorted, blowing the screen grid resistor, and the other tubes were weak as hell.

A new set of JJs and a replacement screen grid resistor later, it biased up beautifully (515v 38mA - well done Apex matching) and there's not a skerrick of hum. Lovely.

A most interesting amp. The schematic is very similar to a Marshall 2203, but it's nothing like that inside.

Its nicely built, but in a very Russian way.

24/06/2026

Well, looks like this one gets the prize for the trickiest damn problem with a Jansen. It came in with the customer complaining of crackling and popping.

When I was sound testing it, the amp continued to crackle and then when pop and died with a really quiet output sound. Never the best thing to happen.

19/03/2026

So here's another tale of woe from the workbench. I have a soft spot for these 5E5-A Pro amplifiers, as I have one myself - a 1956 original. This one is one of the reissues from a few years back, and it's come to me non functional. The owner reports "I was playing it, and it was getting kinda hot, but I'd had a few beersies and it was sounding good so I played on. And then it just stopped."

Oh dear. Better get this one apart and see what ails it. Stick around and I'll tell you all about it.

12/03/2026

I did some work on my personal amp today. Its a Friedman BE100, the flagship model until the BE100 Deluxe came out. Its an astonishingly good amp. This one is a late edition MK II model, from early 2016 (2015 specs).

I have two aims today.

1. Swap out the ARS double vented caps, which introduce a but of light hum into the amplifier. That will only get worse as days go by.
2. Bring it up to 2016 spec. In later 2016, Friedman modified the negative feedback to make the amp more open, and Marshall JCM800-like as people had complained the amp was a touch too civilised (LOL). They also replaced the coupling caps with a different brand, but I don't believe that makes a lot of difference so won't be doing that. I'm also not adding an "S" switch. Its the overall tone change I'm after.

Stay with me and I'll talk you through the mods.

12/02/2026

Apologies to those folks waiting for their amps. It's not that I've not got off my arse to do anything. One of my parts suppliers, Wagner Electronics, have had a massive issue with their international courier Quantum Solutions, and it's resulted in a big backlog getting stuff out internationally. Should be resolved by end of the week, and I'll start getting stuff again next week.

Bear with me. I'll have your amps sorted asap.

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30/01/2026

This amp arrived in the workshop with symptoms of "it won't turn on". Testing revealed that there was no voltage at all coming out of the secondaries on the power transformer, and further testing showed a short in the primary of the transformer. The transformer for these isn't the greatest, and the decision was made, rather than rewinding the transformer, to replace it with a Hammond 291AEX transformer, which will perform beautifully in this amp.

In this blog, I'll show you what is required to replace a power transformer in one of these amplifiers.

29/01/2026

So, I picked up a new amp for myself yesterday. An early 2016 Friedman BE100 - the "Brown Eye", aka the world's best Marshall amp. One of these has been on my list for a while - my main gigging amp is a JCM2000 DSL50, which won't get as much work now.
So, first steps before I go play it was to get it on the bench and make sure its all working okay.