Foreplay III redux Fi edition

[Thermioniclife]

Ok here we go, a while ago i built a new version of the classic Bottlehead Foreplay III. I used 4x 7193 and 1 Od3/VR150.
I love it. During that build i wanted to build it in a Don Garber type chassis but i chickened out. Well i decided to go ahead and design a set of chassis plates to replicate the style of a Don Garber Y Preamp.
Here are some pic's of the panels i have ordered from FPE. I should have them in about 8-10 days. Being impatient as i am i pre built the HV and the Heater supply on wooden blocks, hopefully they will drop in. Each panel will be bent to a 120 degree angle.
Thanks Eileen for the power transformer, Luv ya.
Stay tuned for further developments.
Peace out, stay cool and safe.
,

 

[Thermioniclife]

I prebuilt the Hv and heater supplies in anticipation of the arrival of my panels. I checked them on a printout of the panel.
they should drop in.

 

[pboser]

Cool project and great idea.  I'm confused by the first of the FPE pictures and its title - are you making a preamp or an integrated amp?

 

[Thermioniclife]

Oh, i'm sorry for that. I am building a preamp. I will try to relabel the .jpg

 

[Deke609]

Lee - that's very cool. Are you using PB's suggested trick of cutting a groove in the aluminum plate to facilitate the 120 bends?  What aluminum are you using - 3003, 5052?  When I was making tight radius 90 deg bends to make brackets, I found that 6061 would crack -- but maybe that's not an issue with 120 deg or a more gentle bend.  No visible cracking with 3003 or 5052.

cheers, Derek

[edit: fixed one of the typos]

 

[Thermioniclife]

It may be interesting to some that Don's original preamp chassis is tiny. I painstakingly scaled it and the dimensions are 6 inches tall and when flat before folding it was 8 inches wide. I could not go that small because of the fact that i will be using 5 octal sockets.
So my panels measure 8 inches tall and 10 inches wide when flat.

 

[Thermioniclife]

Hi Derek,
I went with a v groove on the front of the panels using a 60 degree cutter. The panels are 3 mm thick and the V groove will leave 33 thousands of an inch as a hinge so to speak. It should fold to 120 degrees with little or no gap on the front. If you have the front panel designer program go to the edit tab and select scripts and click on raspberry pi. This will give you an idea of doing stuff like this. My fingers are crossed, I do have a contingency plan if this fails but i think it will all work out,again fingers crossed.  As far as cracking, as PB stated the cracking will occur on the back of the panel. I had asked FPE years ago regarding what type of aluminum they used and IIRC they told me 2000 series. I used to work with 5052, 6061 and 7075 But i do not have experience with 2000 series as far as bending.

 

[Deke609]

Thanks Lee. Wow - amazing the tolerances that can be worked with. Those folds should bend easily. And yeah, all the cracks appeared on the outside of the bend not the inside ... and I was using pretty thick aluminum.  Looking forward to following your build progress.

cheers, Derek

 

[Paul Birkeland]

That power supply will not work properly.  The UF4007 diodes are not properly placed.

 

[Thermioniclife]

Ok PB will check, Thanks

 

[Thermioniclife]

Hey PB,
Here is a shot of the underside of the supply. The 2 4007's are connected to what would equate to terminal 6 on the orig FP3 supply.
Do you still have concerns?

 

[Thermioniclife]

Sorry, forgot the pic.

 

[Paul Birkeland]

Ah, I didn't see the rest of that lead continuing under the other diode, that's all OK from that angle.

 

[Thermioniclife]

Roger that PB, thanks for the check, I appreciate it. Please feel free to chime in if you sense danger. Sometimes photos, especially mine,
can be deceptive.

 

[Thermioniclife]

Hey Derek,
As far as the V groove, i am a little concerned about the fact that FPE does not offer a true 60 degree V channel, you have to have a minimum of a 1 mm flat bottom on the bottom of the V. Therefore i am a little concerned about the accuracy of the bend in general.
But time will tell.I just got shipping confirmation from FPE that i should receive my panels on the 29 th of this month. I am excited to say the least.
Regards, Lee

 

[Paul Birkeland]

I used to work for FPE, and we had loads of customers put grooves in our panels and bend them.  The anodizing may crack a little bit on the outside radius of the bend, but that hardly matters for what you're doing.  The 5005 alloy is super soft, so it bends pretty well.  It also scratches pretty easily...

 

[Deke609]

You could consider bending them the opposite way - with uncut surface facing out. Couldn't use the 60 deg cut to guide how far to bend, but I bet you could rig up a guide out of wood or something.  Just a thought. Not a suggestion. And then again, a perfect thin groove in the "corners"might look like a pretty cool intentional design feature.

cheers, Derek

 

[Thermioniclife]

Thank's PB,
I thought that they told me that they used 2000 series aluminum but i will accept your statement that they use 5000 series.
I am not so concerned regarding the cracking on the outside of the radius which will be on the inside but rather they do not offer a V groove as opposed to a V groove with a 1 mm/ .03937 flat on the bottom of the groove. This can put variables on the fold point. As i stated before i think all will be well, although we shall see. Stay tuned for another exiting episode of this build.
Regards to all.

 

[Thermioniclife]

Panels arrived yesterday. progress so far. Kinda tired now, i was up at 4:30 am and it's 7 pm now. Enjoy the Pics and i will expound ad 
nauseam in the next exciting episode of this build. Stay tuned.

 

[Thermioniclife]

Forgot a couple.