Subminiature tube amplifier

[Thomas_H]

Hi guys,

my new build is another subminiature amplifier, normally they don't show up here, so I created this post...

it's based on Frequency central's "vibratone" (a Murder one with tremolo).

It uses hearing aid subminiature tube 5672 and the output transformer, that should have 20k in the primary, is a 220 to 6v transformer that I rearranged the laminations to obtain the air gap.

With a bigger speaker it sounds better, but has almost no headroom.

Is a nice late night amplifier, and headphone amplifier.

the schematic is here:
http://www.diystompboxes.com/smfforum/i ... ic=83831.0

and some images:
[img682]http://i1303.photobucket.com/albums/ag1 ... 5ecb38.jpg[/img]
[img682]http://i1303.photobucket.com/albums/ag1 ... b9783a.jpg[/img]
[img682]http://i1303.photobucket.com/albums/ag1 ... 4a6814.jpg[/img]

The small combo should look like an old tube radio or an earlier gibson amplifier but my skill with the saw is a shame. I made the front with a drill and a small metal saw and tried to correct my bad cutting skill with sanding.

The chassis I made from a small metal sheet.

http://www.youtube.com/watch?v=c5XCDiHzptc
the video was made from the rear of the amp with the camera mic.

hope you like! it was a nice learning process.

Thomas

[cbass]

Very cool project! I e never dealt with subminatures would a fender reverb transformer work for an OT

[bluesfendermanblues]

Cool, you could make miniature copies of the larger icon amps. Business idea!!

[cbass]

A mini twin with 4" speakers would be awesome

[Thomas_H]

that's a great idea! I should try some more design ideas!
A small tweed amp would also look nice!

[Leo_Gnardo]

Cool project! The hi fi types call a mini amp like this a "spud", like a potato-size amp. You can't expect a lot of volume as a small amp like this might come up with a watt or so, and small speakers tend to be not very efficient. OTOH I'll bet it sounds like a big stack if you mic it up and record or send it thru PA.

[cbass]

I wonder what small speaker would make the best guitar speaker . full range are a lot less sensitive maybe a ported midrange might need a 5¹/⁴ or 6 to even begin to cover the low e

[Thomas_H]

I'm currently building another amplifier with a Jensen mod 6" speaker. It's a half of the 18watt combo. I'm using a open back and a 3w amplifier with big tubes. Would the 6" Weber be louder than the Jensen?

Some hi-fi speakers have a high sensitivity (and price). There are also old radio alnico speakers that would sound line old harp amps.

[Cantplay]

I've always defined Spud Amp as only 1 tube.

John

[matt h]

(deleted)

[Leo_Gnardo]

Agreed, the spuds were always one-tubers in my brain.

I took spud to mean any tiny build, say up to half the size of a toaster or so. Oh well.

one-tuber, I get it... well maybe so but what if you put an eye tube in it?

Thanks for helping me ketch up.

[LeeMo]

Great looking build!
You might not be aware that another member here Dana Hall who goes by the handle UR12 built a Trainwreck Express http://ampgarage.com/forum/viewtopic.ph ... bminiature
and a Plexi http://ampgarage.com/forum/viewtopic.ph ... bminiature
He offered both as kits.

LeeMo

Edit: I just found this also.
http://ampgarage.com/forum/viewtopic.ph ... bminiature

[M Fowler]

I didn't build Dana's little amp but did build rjguitars Rocket Pocket amp and it was a great sounding little machine.

Mark

[stretch2011]

I own a microppexi. It rips! And micd through the pa it rips even louder. Sounded better than my buddies micd jet city 20watter.

[Leka]

I built Dana's Little Devil and it totally rips!
I have played with different tube setups and there is still a lot of experiments to be done. I love these little tubes.