2w Sub Miniature Express

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UR12
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2w Sub Miniature Express

Post by UR12 »

I am kind of caught up on builds at the moment and had some free time to play with some new ideas. A Local friend turned me onto a few of the Subminiature tubes and I though I would see what I could make with them. I decided to see if I couldn't build a miniature bedroom amp. The idea then evolved into putting a complete Express on a small PCB board that measures 4" x 8" (Less power supply) I came up with the design on the board and ectched up a prototype to test the amp with . This test board is single sided and will have jumpers for the top copper side. I will have some professional boards made up if the thing sounds worth persueing. I know there has been some use of the 6112 preamp tubes in Wrecks before but I am also using the Sub mini 5902 beam power pentode tubes in a PP configuration. The pots are all 1/4w. I'll try and keep this thread updated if anyone is interested. I am calling this one the Lil' Devil :lol:

Here are a few pics of the prototype board with all the parts installed (Minus the top Jumpers). All resistors are 1/2w except for the 1w screen resistors and the 1k3w that replaced the 25w. I included a pic of my Ipod Nano next to the board to give you an idea of the size. :lol:
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Last edited by UR12 on Sun Aug 03, 2008 3:44 pm, edited 1 time in total.
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bigmik
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Re: 2w Sub Miniature Express

Post by bigmik »

that is about the coolest thing i have seen in a while ,how do you think this stuff up? can't wait to see and hear the final product.
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VacuumVoodoo
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Re: 2w Sub Miniature Express

Post by VacuumVoodoo »

Spring loaded 8 pin DIL sockets for tubes. Cool.
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UR12
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Re: 2w Sub Miniature Express

Post by UR12 »

bigmik wrote:that is about the coolest thing i have seen in a while ,how do you think this stuff up? can't wait to see and hear the final product.
Thanks! I guess I just have a warped mind :lol: I can't wait to hear it either :shock:

VacuumVoodoo wrote:Spring loaded 8 pin DIL sockets for tubes. Cool.
Yes, In the true spirit of Ken Fisher I decided to to use what I had laying around. :D They fit the bill so I went with it. If they cause me any trouble I will either solder them to a 8 pin dip header and plup them into the sockets that way or just solder them directly to the board without sockets the way they were intended to be installed.
Tubetwang
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Re: 2w Sub Miniature Express

Post by Tubetwang »

Keep us up on this here Lil' Devil Dana...

Most interesting!
El_Martin
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Re: 2w Sub Miniature Express

Post by El_Martin »

WAY KEWL, Dana! :shock:

Did you put our regular Express in the washing machine and hit the wrong temperature button? 8)

Like small amps!

Wonder how she sounds like. My Lil'Wreck uses on 12AX7/ECC83 and half of 12AU7/ECC82 as SE output and quite low voltages <170V. It's nice, but triodes are not pentodes nor do they sound exactly like 'em.

Ciao
Martin
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gearhead
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Re: 2w Sub Miniature Express

Post by gearhead »

Oh my word, you are indeed a tubehead SuuuperGenius!

Keep posting, this is just sooooo cool.
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UR12
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Re: 2w Sub Miniature Express

Post by UR12 »

I just ordered trannys so I guess they will be in next wednesday. At that rate I should have it fired up one day next week. I went with Hammond off the shelf trannys to start with a 129ax for power and a 125a for the OT. I'll be running the outputs at either 5.6k or 6.8k.

I am looking for a good 5 or 6 inch guitar speaker. If anyone has any suggestions I would love to hear them.
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thousandshirts
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Re: 2w Sub Miniature Express

Post by thousandshirts »

This could be a really fun amp to play. I'll be reading closely. Thanks for sharing!

Regarding your words about speakers, I know Weber offers two 6" speakers, one ceramic ($30), and one alnico ($45), for use in the small, early Fender type amps. 15 watts each, and the alnico has three different cone options.

https://taweber.powweb.com/weber/asig6.htm - Alnico
https://taweber.powweb.com/weber/csig6.htm - Ceramic
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Lonely Raven
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Re: 2w Sub Miniature Express

Post by Lonely Raven »

Dibs on one when you have one to sell, Dana!! 8)
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gahult
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Re: 2w Sub Miniature Express

Post by gahult »

Were is the VVR???? :? LOL
Interesting.

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Lonely Raven
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Re: 2w Sub Miniature Express

Post by Lonely Raven »

VVR? For that thing, he'll have to start working on a Turbo! :lol:
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Wayne
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Re: 2w Sub Miniature Express

Post by Wayne »

El_Martin wrote:...triodes are not pentodes nor do they sound exactly like 'em.
Wonder what PP cascode output would sound like. Anyone ever try it? Would it be a pain in the ass?

W
El_Martin
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Re: 2w Sub Miniature Express

Post by El_Martin »

Wayne, it takes an equally warped tube mind to think of that. :twisted:

While dabbling w. my Lil'Wreck I thought a second about it...why not try? Nothing to lose.

Ciao
Martin
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Re: 2w Sub Miniature Express

Post by Wayne »

Well, if you've got a platform you can easily try it on, do keep us informed. I've got something else on the go right now, and a lot of other drama going on as well, so I can't really try it right away.

Hopefully, it would come closer to the pentode sound. I can't say I've ever heard triode output sound that I liked (does "triode mode" on a pentode amp even count for this?), and I don't know of a small pentode that's in new production/readily available except the EF86 - haven't read too much good about those..

W
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