Deluxe Micro build/first amp build

Kev-wilson

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Wire again, I swooped on an Ebay 'job lot' bargain advertised as 22awg solid core wire
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but after my winning bid a Google search indicated it's possibly stranded, cost me £18 with an iphone earpiece thrown in :lol: so fingers crossed it is solid core...
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It’ll tidy up and next time I’ll get thinner plate 😩
 
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Kev-wilson

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A little more sanding and it’ll be reet (Yorkshire for near enough 😝) I’ll use 1mm sheet next time as that was hard to bend, I’ve had to lower the front panel to get more chassis showing.

Soon be time for some electrontricks but thought I’d have a crack at the tin bashing and wood butchery first 😇
 

Kev-wilson

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I made a template from the PT in the first one as a drilling aid, turned the valve based the wrong way too 🧐

Bought a 10” Jensen alnico speaker so have a cab to knock up for that, got bits for a bulb limiter so it’s time for the turret board to get some turrets.
 

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Kev-wilson

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A bigger speaker cabinet than the first one and I’ve got a 10” Jensen alinico to go in it, I’ve been a bit short of spare time lately and am expecting/hoping for the PT this week so may have a busy bank holiday 🙂
 

Kev-wilson

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I had a mate round this evening who can play a bit so got a sample up onto youtube played thru my Tele, and the speaker cab version 2 is about done, and the power transformer must be about ready, or, I hope my PT is nearly ready :)

A better sound clip

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Kev-wilson

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Does that look ok? I’ve double checked but it doesn’t hurt to ask 🙂

I’m ok with metal and wood things but there’s still magic and sorcery going on there on that board 😀

My mate who did me my little sound clip was impressed with the amp and he plays in a band, for me it was nice to hear it played properly 🙂
 

Kev-wilson

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Not much room for my hands to solder in there but its a job for another day, hopefully I’ve done the heater wiring correctly and the twists are ok.
I’ve made the light bulb limiter so just waiting on the PT to arrive 🙂
 

Kev-wilson

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Wish me luck! 🤞as I’ve double checked everything and wired the OT correctly this time 😝

First power up shortly when I’ve had a cup of tea to calm the nerves!

edit 1/ 346v on B+1 so I’ll give it a sound check ❤️

Edit 2/ no sound, not a peep 😩

Edit 3/ we have sound :) I'd not seated a valve correctly!
 
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Kev-wilson

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It's a funny old world as I seem to have a 'left over' box of bits :p and don't know what to do with them 😃 a micro Bassman looks tempting although I'd love to have a crack at a low wattage vox but can't find anything to copy and I don't have a clue how to design one, I could maybe copy an AC4 and use a 75% attenuator, but again attenuators are a new thing to me, I have a Vox NT clone and am debating whether to sell it on or build an attenuator for it.

I've plugged both amps into a boss pedal and played them at the same time which was fun :) but not had time for a jam night yet, the 10" Greenback does have a different sound to the 10" Jenson alnico but both work well with the amps, it probably doesn't help that I made the 2nd speaker cab a fair bit bigger and deeper, but it looks nice so a little bitter sweet.

I shall for ever feel guilty as on Wednesday whilst 'testing' the amp with some punk chords, as well as 'Teenage Kicks' by the Undertones I played a S*x Pistols ditty which turned out to be inappropriate, but I guess that's rock and roll...
 

wangdaning

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It's a funny old world as I seem to have a 'left over' box of bits :p and don't know what to do with them 😃 a micro Bassman looks tempting although I'd love to have a crack at a low wattage vox but can't find anything to copy and I don't have a clue how to design one, I could maybe copy an AC4 and use a 75% attenuator, but again attenuators are a new thing to me, I have a Vox NT clone and am debating whether to sell it on or build an attenuator for it.

I've plugged both amps into a boss pedal and played them at the same time which was fun :) but not had time for a jam night yet, the 10" Greenback does have a different sound to the 10" Jenson alnico but both work well with the amps, it probably doesn't help that I made the 2nd speaker cab a fair bit bigger and deeper, but it looks nice so a little bitter sweet.

I shall for ever feel guilty as on Wednesday whilst 'testing' the amp with some punk chords, as well as 'Teenage Kicks' by the Undertones I played a S*x Pistols ditty which turned out to be inappropriate, but I guess that's rock and roll...
I think if you do a Vox preamp and an EF80 power side a la Rob it would work out. I am sure if you started it many people here could help out. It is a nice forum.
 

Kev-wilson

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I changed one of the amps pre amp valves to a Ruby 12ax7 (as there's 2 sat idle in an amp on the floor :p ) and by heck it growls and chugs like a good one :) I've left my mates Strat plugged into it and will enjoy the look on his face next time he comes :lol:😂😇

I'll try the Bassman micro next I think, a full size Deluxe is tempting as I'm going to get an attenuator for the Vox clone, but I think I should do the little Bassman as a winter project but will start a new thread for that and enjoy a couple of months first playing the ones I've got whilst learning more theory.
 

Kev-wilson

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I've a question about this transformer, if I used the +10v & 240v primaries, would I get around 240v (480v) at the secondary?

The RobRob Bassman Micro shows a Hammond 370 with a 240v secondary so I'm hoping I can use this type using the +10v and no extra voltage dropping resistor.
 

King Fan

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View attachment 1036030

I've a question about this transformer, if I used the +10v & 240v primaries, would I get around 240v (480v) at the secondary?

The RobRob Bassman Micro shows a Hammond 370 with a 240v secondary so I'm hoping I can use this type using the +10v and no extra voltage dropping resistor.

Whoa, I got all confused. I stepped away for a couple weeks and your Deluxe Micro suddenly became a Bassman Micro. :) (I like your idea to start a new thread.) I take it you're going for the 12AU7 version, with the 240V Hammond as 'model' PT? And an EZ81 rectifier, maybe?

I might've known this a few months back when I was sweating HT voltage and B+ issues, (tho I built an EF80 type) but is there some wiggle room upward on the HT here? Would 250V be bad? I forget if folks find their 240V Bassman Micros coming in just right, or high, or low on B+ and bias. But there are a lot of 12AU7 BMMs out there, so maybe you already know... or those builders could chime in.
 
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2L man

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View attachment 1036030

I've a question about this transformer, if I used the +10v & 240v primaries, would I get around 240v (480v) at the secondary?

The RobRob Bassman Micro shows a Hammond 370 with a 240v secondary so I'm hoping I can use this type using the +10v and no extra voltage dropping resistor.
Yes, Mains input voltage effect to PT output voltages. There are options for 220V, 230V, 240 and 250V. Filament voltage is one variable which define what option you can optimally use but tube datasheets give quite high tolerance. It is easy to install a series resistor to filament circuit to drop too high voltage if you must use lower input voltage wires to increase HV output voltage. Just test +10-240V first and if you need higher filament voltage test 0-240. Next +10-220. Highest outputs come when Mains is fed between 0-220V

That 250V/80mA is a rating and output is higher when less current is taken. Only testing reveal how output behave. That rating is also AC to resistive load and rectifying and filtering stress transformer differently when current flow thru PT only short bursts and they cause more voltage loss

When both secondarys are connect parallel and a bridge rectier is used DC current max calculates: 160mAAC : 1,41 = 113mADC. DC output current potential drop by divider of 1,41 because filter capacitors try to fill the space between rectified sine waves and charge current pulses come higher. When CT power supply is used DC current max comes still bit less (perhaps about 105mADC) and it is because current afternate between secondary halfs and stress wire bit more than Bridge rectifier where current flow thru whole secondary.
 




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