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Post by bobfury on Aug 5, 2014 22:40:32 GMT
Here is an amp I'm working on for a friend. An original Model T. It has some safety issues with the mains input that need sorting out, but other than that it's very clean, has the original 6550 valves which all test fine, and doesn't even require any new capacitors or replacement resistors. Just a bit of contact cleaner on the pots. I haven't powered it up yet as I'm waiting on a 3 pin US plug so I can have the chassis earthed when I fire her up, but looking forward to hearing it do the business. Attachments:
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Post by Tony on Aug 5, 2014 22:58:00 GMT
This amp has a lot of hype surrounding it. I can't wait to hear how it sounds once you've finished tinkering with it.
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Post by Frank on Aug 6, 2014 0:03:50 GMT
I love working on tagstrip amps like that, everything's so clearly laid out and easy to work with. And those nice big bias trimpots are good, no flailing round trying to turn a teeny little screw on a PCB. Amps like that can fall down a flight of stairs and still work.
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Ryan
New Guy
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Post by Ryan on Aug 6, 2014 10:07:39 GMT
Jealous doesn't even begin to describe how I feel about this.  |
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Post by Blankplank on Aug 6, 2014 11:32:11 GMT
Jealous doesn't even begin to describe how I feel about this. You were the first person I thought of when I saw this, hahah! |
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Ryan
New Guy
Posts: 17
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Post by Ryan on Aug 6, 2014 12:08:12 GMT
It's what prompted Tony to invite me to the site!  |
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Post by bobfury on Aug 6, 2014 13:13:59 GMT
My friend is a bit worried that converting this to run on 240v (which i think should be possible with its original mains transformer) might alter the tone of the amp. I've told him I'll make a lot of notes on voltages and the operation of the amp before I try a 240v wiring setup, so I can make some before & after comparisons. While I'm at it I'll probably work out some of the output transformer spec and so on. I'm tempted to try making a small run amps based off the model t but probably on turrets and with very high spec parts and custom iron. Modern tastful styling. Nice hardwood front, that sort of thing.
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Ryan
New Guy
Posts: 17
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Post by Ryan on Aug 6, 2014 13:34:23 GMT
I would have guessed that putting in a new transformer to run on 240v might have a more detrimental effect on the tone of the model T than converting it, but then I could be (and most likely am) talking complete bollocks.
Might I ask where on earth you found this thing? I've been desperately searching for one for years now.
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Post by bobfury on Aug 6, 2014 14:55:47 GMT
It belongs to a friend. I'm looking it over because it keeps giving out electric shocks. He's had it for a number of years and I'm pretty sure he imported it. Obviously its very different to the 2nd gen Model T and the Fender reissue.
If i was to put in a totally new PT then the output would have to be within a number of volts of the original for it to be less risky. I don't believe small changes in voltage at each stage are that audible but the performance of the PT would also need to be similar. Similar sag at high power levels etc... all that. The original has a dual primary wired in parallel, which is the norm when you see 120v/240v primaries wired for 120volts. Usually to wire for 240v you wire the two primary sections in series. If the winds are all ok then you should get close to (if not the same) voltages out of the secondary. It's what happens on amps with a 120v/240v mains switch. That switch is just connecting the input to the PT differently. So if it's possible to run 240v into the original PT, thats the best bet. It's also a very minor change and totally reversible.
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Ryan
New Guy
Posts: 17
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Post by Ryan on Aug 6, 2014 15:05:40 GMT
I'll keep a keen eye on this thread as it looks as if I'll have to import one in my quest to own one so your findings will no doubt help me a great deal should I manage to find one. That being said, if the dude ever wants to sell it I'd probably bite his hand off to get it. |
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Post by bobfury on Aug 22, 2014 12:16:48 GMT
Hello, just wanted to say I got this amp working and sounding great. He was reluctant to try the 240V wiring but I still think that should possible. The 'death cap' had broken and the chassis was live as soon as I applied power. I took some photos and put a little slideshow on my site and did a blogpost about the death cap. www.meresound.com/blog |
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