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Comments
If you can see any markings on the output transformer (the one sitting on top of the chassis), they might be useful to confirm this. I highly doubt that you'd do any damage in any case.
(The modified version has different tone controls and no negative feedback.)
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Interesting that you say the output won't be anything like 4.5 W, I assume it will be lower? I had assumed it would be a very low power amplifier, that was one of the reasons I bought it (possibly better as a hi-fi amp ?), so that's fine. I have an old tweed princeton which is 4.5 W output and that's fairly loud for 4.5 W but once the volume gets to, say, 2 o'clock it just gets dirtier rather than louder. However, it uses a 6V6 output valve which probably makes a difference? That's also a 4 ohm output coincidentally.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Hi Guy, glad to see you delving into more dusty stuff from the 50's. As MisterG confirms the schematic is definitely indicating a 4ohm output. Those small single ended output transformers tend to be 5K ohm primary with a single 4 ohm output. They were used in large numbers for single ended mono amps in radios, record players etc.
The unmodified circuit looks as if it will be quite tame, been designed to keep distortion down. The modified circuit is quite the opposite!
If you've got a 4 ohm and an 8 ohm speaker available I'd try both and see which you prefer. Running into an 8 ohm load, with the EL84 running so "cool" on its anode, the higher reflected primary impedance on the O/T shouldn't do the valve any harm, even long term. The 8 ohm should be slightly louder, though you may not be able to detect it. Whichever ohmage speaker you plump for, if volume is an issue, the best thing would be to get the most efficient speaker you can.
Many thanks for that and yes, it seemed like a nice little inexpensive amp and it may or may not work for guitar. The guy I bought it from was using it for guitar and said it sounded amazing but I'll wait and see.
GREAT to know that I could potentially run it into 8 ohms without any major damage, that's great. I have 3 2x12 cabs that are currently wired for 8 ohms so I'll mess about. Unfortunately I don't have any 4 ohm cabs but do have the 4 ohm Weber in the princeton and as the speaker is connected to the chassis via a phono I can just make up another lead and try the Linear through that. I can then compare the 4 and 8 ohm cabs.
You mentioned you had gone down the valve route with hi-fi Gordon, if this doesn't work out well for guitar could I use it in conjunction with a hi-fi?
As you were.
Reading this thread sent me down memory lane.
In the mid 70s there was an electronic surplus shop in my area that sold Northcourt Cage amps (the Thirty and Fifty) . I believe the Linear and Northcourt brands were a rebadged generic amp made by some company in Essex back in the 60s. To us impoverished kids [back then], these were pocket money amps (the Northcourt Thirty was £11.50) compared to a Marshall 100W MV head which was around £200.
Those amps sound amazing,
Oh how times change !
Yes, me too! I remember the old Northcourt and Linear amps.....they were excellent little amps, in some cases not so little !, and as you so rightly say an alternative to mainstream brands like Marshall which were impossible to afford.
I was a struggling guitarist in the early 70s and as I've tried to explain to so many people, there wasn't such a thing as vintage amps or speakers or guitars back then....they were either 'just' affordable or impossibly expensive. Nobody I knew had new gear. It was bits and pieces put together that probably sounded terrible but it didn't matter.....you were playing!! Those were the days........................
It appears they were made in Leeds.
http://www.chambonino.com/work/linear/info1.html
http://imageshack.us/g/1/10383589/
The amp is really quite remarkable....as ICBM and ESChap said, it's not loud but it's sweet as you like. Turned up full the drive/crunch, whatever you want to call it, is just wonderful through a 2x12 at 8 ohms. With a treble boost in front it really makes it a much more viable option with bags more volume but without compromising the original tone.
The tone controls are pretty amazing too.....they really do have a good sweep but not radical so you can get the tone 'just right'. I often find that EQ is either interactive which doesn't suit me or has far too much sweep.
I know ICBM asked if there were any markings on the transformer but sadly not. The wiring is pretty much perfect and done to a high standard. The chassis looks almost new and the pots are original but feel like they're brand new so I suspect this amp hasn't been used much in its lifetime.
The solid mahogany cab is a nice touch!! To give an idea of scale........this on top of a 100 watt head:
http://img843.imageshack.us/img843/5913/iwvj.jpg
The tone control network (James / Baxandall ??) is different to the "normal" arrangement used by Fender, Marshall, etc. so interesting to hear your comments on it.
It's rare that you grab a tone control and it does what a tone control should do......give you a nice graduated and unsaturated response. Comparing it to a Marshall......well, I don't think you can compare it they are so different. The tone on this little fella really does graduate so perfectly and the bass and treble work really well together.
To be honest the volume control is great too.....although the range isn't great in terms of volume available it really does lay it down so smoothly. I guess this is a characteristic of a low volume amp.......the difference between zero and full power is relatively small.