Thread: A shed Hi Fi project

A couple of weeks ago the road to town flooded for a couple of days and I was trapped at home with no where to go but the shed ......I was devastated!... no really, all my projects are in a mate's workshop in town at the moment. I had no choice but to bite the bullet and start another project. Once the horrifying thoughts of being "Project Free" had faded, I thought I'd start a long delayed project and do a bit of chassis bashing to make the case for a stereo amp for the shed. The John Heine foot powered guillotine really makes life easier for the sheet metal work for the top and bottom covers, and the home made 12" disc sander lets me make a precise 45 degree mitre on the gold aluminium extrusion for the sides. The covers had a coat of dark hammertone blue as I have a 4 litre can of that on hand and as they say, "Hammertone covers a multitude of sins".

I have a good stock of electrical stuff so I decided to build a retro style valve amp based on a design on the Internet. It's not complete yet but it's at the stage where I can power up the filaments and see what it'll look like when complete. The final part order turned up Friday arvo so now I have a bit of soldering ahead before I have a unique amplifier for the shed stereo. It'll need a cage on it to prevent zapping the unwary with 320V dc from the valve top caps.

I'll reattach them and see if that fixes it.

Hi Graziano, sounds like a great project, but you could make it a much bigger one if you followed this fellows example. Apologies if you have already seen this video, but I imagine that many of the members here would not have seen it, and some may find it interesting.
[ame="http://dailymotion.alice.it/video/x3wrzo_fabrication-dune-lampe-triode_tech"]Fabrication d'une lampe triode - Vidéo Dailymotion[/ame]
Incidentally it may just be my computer, but I only get generic picture icons, and no images for the 4 pictures you added to your post, are you seeing them yourself?. Cheers,
Rob.

Sadly, I can't view the photos either.

BT

Originally Posted by Ropetangler

Hi Graziano, sounds like a great project, but you could make it a much bigger one if you followed this fellows example. Apologies if you have already seen this video, but I imagine that many of the members here would not have seen it, and some may find it interesting.

Incidentally it may just be my computer, but I only get generic picture icons, and no images for the 4 pictures you added to your post, are you seeing them yourself?. Cheers,
Rob.

I have seen that video before, it's a pretty good solution to getting hold of a rare valve....fabricate it yourself. The pics show up as working links at this end, it may be a moderator thing, though they don't show up at the bottom as icons though.

Edit, ok I've attached them again and they seem to have stuck this time.

Great looking photos there Graziano, at that rate BT will have to stay on his toes to keep his well earned reputation as Top Dog Photographer. I take it that with the high level of finish displayed on the amplifier chassis, there are no plans to hide it in a case, -(Glass cases excepted.)
Rob.
ACHTUNG! ALLES LOOKENSPEEPERS!

Das grossnoisemachine ist nicht fuer gefingerpoken und mitten grabben.

Ist easy schnappen der springen werk, blowenfusen und poppencorken mit spitzensparken.

Ist nicht fuer gewerken bei das dumpkopfen.

Das rubbernecken sichtseeren keepen das cotten-pickenen hans in das pockets muss; relaxen und watchen das blinkenlichten.


You could add a sign similar to this old faux german piece of humour in lieu of building a cage to keep the Lookenspeepers off the hot bits. Once bitten, they wouldn't be likely to make the same mistake again. Small children, not yet able to read and comprehend, could be an issue though.

Originally Posted by Ropetangler

You could add a sign similar to this old faux german piece of humour in lieu of building a cage to keep the Lookenspeepers off the hot bits. Once bitten, they wouldn't be likely to make the same mistake again. Small children, not yet able to read and comprehend, could be an issue though.

Rob, that faux German sign is just about right, it reminds me of that document designed to cut down on swearing in the workplace. They came out about the time I worked for a Dilbert style pointy haired boss who thought he was a gun technician when in reality he was nicknamed the "Ten fingers of Death" .

The amplifier has live bits on the outside like the tops of the output valves so I'll most likely make something out of acrylic and perforated mesh to give some safety and also keep the hordes of geckos out of the works as they have totally infested the shed since I built it a few years ago. I just realised the inspiration for the amp was seeing all those garages and workshops with the old bakelite valve radios, usually the case was long gone but the bare chassis with speaker on top worked enough to give some workshop music.

Here's the link to the designer's website that the amp is based on: ECONOMICAL VALVE BASED AUDIO POWER AMPLIFIER

Hi Graziano,

Nice neat job, I like it.. brings back fond memories.. I used to build valve amps for 2M amateur radio. When it comes to getting power you can't beat high volts.

What are you feeding it with? I just ask because I'm currently doing an FM tuner design based on the Si4703.. I can send you a board to play with..

Regards
Ray

Originally Posted by RayG

Hi Graziano,

Nice neat job, I like it.. brings back fond memories.. I used to build valve amps for 2M amateur radio. When it comes to getting power you can't beat high volts.

What are you feeding it with? I just ask because I'm currently doing an FM tuner design based on the Si4703.. I can send you a board to play with..

Regards
Ray

Hi Ray, 2M amateur radios would push the usual miniature valves to their limits, did you use any of the 4CX series ceramic tetrodes?. I have a few canned military 4X150's still inside the protective olive green tins, they were for B52 jammers I think. As far as the amp goes, I'm just using an MP3/FM radio and a Technics SL1300 turntable that I picked up up for a dollar as per the unspoken shed sound system rules.

The Si4703 looks like a very modern FM radio IC, I'm tempted get one but I'd better focus on the jobs at hand. Now the weather's come good I have to get the roof on the shed extension etc. etc.

Hi Graziano

nice job. Well done.

QQEO6/40s for me; no blower reqd like the 4CX150/250 etc.!
Still have a few here! Now where's those sockets?

73, mike

Originally Posted by mike48

Hi Graziano

nice job. Well done.

QQEO6/40s for me; no blower reqd like the 4CX150/250 etc.!
Still have a few here! Now where's those sockets?

73, mike

I'm on the lookout for QE08-200's if you hear of any in your travels, I bought some from the shortwave site near Darwin before they closed down. They were driving the output stage.

Hi Graziano, mike48,

I got a number of army surplus 4CX250's for 2M SSB (I've also got some 4X150A's I think) I think the plate supply is still under a bench somewhere... and used to run a 2C39 on 23cm 50 Watts into a 3M dish

I never used QQE06/40's. but I know a guy who might have some QE08-200 when I see him I'll ask.

Regards
Ray

(73 de VK3YNV)

Hello guys

Graziano, sorry no QE08/200s here, nor do I have any experience with them.
Ebay if you must have them.

Could use the more available and cheaper QB3/300 or the identical, ubiquitous, and enigmatic 4-125 if you could change the filament supply easily to 5V and re-arrange the pin wiring just a bit. The sockets are the same (jumbo 5 pin).
The QB3/300 has a higher GM; need to watch that.

We used to use heaps of QB3/300s at VHF, and as AM modulators.
Can run the carbon plates light red, no worries.
Tough tubes.

73 (4GV)

cheerio, mike

Nicely done. The blue and gold looks great. I'm intrigued by all those RCA sockets on the rear. What are they all for?

Originally Posted by jack620

Nicely done. The blue and gold looks great. I'm intrigued by all those RCA sockets on the rear. What are they all for?

They will be five stereo source inputs.

That video is a delight. Thank you Rob.

And thank you Mark.

I remember fooling around with a valve radio when I was 14. The mesmerising glow of the valves.... it all seemed understandable back then.

BT