Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Foreplay III => Topic started by: Thermioniclife on July 20, 2020, 11:58:27 AM
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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.
,
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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.
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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?
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Oh, i'm sorry for that. I am building a preamp. I will try to relabel the .jpg
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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]
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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.
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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.
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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
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That power supply will not work properly. The UF4007 diodes are not properly placed.
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Ok PB will check, Thanks
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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?
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Sorry, forgot the pic.
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Ah, I didn't see the rest of that lead continuing under the other diode, that's all OK from that angle.
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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. :)
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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
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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...
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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
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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.
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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.
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Forgot a couple.
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I wish Doc B. would let me put labels like that on certain things...
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But that would have scared me off from diy audio! Then again, being an FW, I probably wouldn't have heeded the warning ;D
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But that would have scared me off from diy audio!
Such a label wouldn't be applied to a kit ;)
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The fundamental issue is that a fuckwit will open it anyway, warning or not. That's why they are a fuckwit. Come to think of it, I guess that makes me a fuckwit.
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We all are fuckwits at times. I still remember when i was about 5 years old and i stuck a wire in a wall outlet.
That was the seminal moment that shaped my misguided life!
Making progress today, will post pic's later. It's been 2 and a half weeks with temps in the upper 80's to low 90's and high humidity.
I'm melting.
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Ok, today's progress.
The first pic is the back of the power panel complete. the second pic is the front panel as i progressed today. The tube side is complete except for the grid and plate cap wiring because that will happen after the panel is bent. On the left side i am in the process of wiring the input selector, balance and volume control in which i will then remove once completed and transfer to the input panel for final wiring,
At that point when final assembly occurs all i need to do is secure those 3 control's to the front panel. Hopefully. Hey Bottle head crew, i'm gonna try a 10k balance pot, any thoughts? Peace out all, stay cool and safe.
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i'm gonna try a 10k balance pot, any thoughts? Peace out all, stay cool and safe.
Since the FP-III didn't come with one, you'd need to draw out what you plan to wire up and we could comment.
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Outstanding work - this thread is just the thing for the monotony of quarantine (quaranotony?).
Will you enclose the edges to exclude the probing fuckwit fingers, or will this preamp do double duty as something of a fuckwit porchlight/bugzapper?
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IIRC Don used perforated metal to make grills over the gaps between the panels.
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Roger that big daddy, i have a couple of in wall spk brackets with perf metal wings that i can use. Gotta find them but i know i have them. i used to be in that business.
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Ok, more progress. I have all the wiring done on the front panel except for the grid and plate wires soldered which will happen in the next day or two, after i bend the front panel. I have cut and bent the F.W. finger protectors, they are ready to install. and lastly the input panel is bent and the input padding resistors are installed. Btw we are in the midst of the first tropical storm of the season, anybody want want to come to the north fork of Long Island N.Y. to pick up some fallen limbs? Hey Doc i heard that lawn care is your side job.
Sorry, i just could not resist. I know, i'm a jackass. Peace, Love and happiness to all.
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Nice! How did you bend the perforated sheet (aka FW finger protectors)?
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Oh, bad timing, what a shame. Our son and his fiance postponed their garden wedding until next year and I have temporarily retired from landscraping. But I will send pleasant thoughts your way as you sweat over the chainsaw and chipper.
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Roger That Doc, Sorry To here that u Are not available, perhaps i can find someone else. Say hi to Queen For me, Luv you both.
Deke, i bent the F.W. protectors by hand using the last flat(unbent panel) with the standoff's installed and a couple of spring clamps to hold the previously bent corner. Again, P.L.and H to all. I'm out 4 Tonight.
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Hi Lee,
I'm a reformed Long Islander from Suffolk County. Good luck with the weather event.
Hey I have something cool if you want it (and if I can find it). Bottlehead often presents, "while supplies last" type offers. For example recently a premium RCA 12AU7 clear top was offered with the next X number of Crack kits... That sort of thing. Well years ago when I bought my FPIII the goodie was a Vitamin Q bypass cap for the 0D3. I upgraded to the Extended Foreplay which eliminates the 0D3. Somewhere I have that cap still attached to an octal socket. I no longer have a need for it if you want it. I can also put some NOS 0D3 tubes in the box. No charge to you. I'll even pay for slow boat shipping. Just let me know.
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Hey Natural Sound,
I got lucky this time, no damage and never lost electricity. Just a bunch of limbs and branches down.
Thanks for the generous offer but you should keep those items, you never know when that cap may come in handy.
Thanks again,
Regards.
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Okey Dokey, I am so close to hearing music. Got the front panel completely wired as well as the power and input panels.
All that is left is to hook up the B+ and heater wiring.
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Hey Folks, I know some of you may find this hard to believe but, I AM AN IDIOT!
I finished the wiring and did a resistance check and all seemed fine( i thought)
I then plugged the power in and the monkey flipped the switch. The 0D3 fired up nicely measured 146 vdc on the plates awesome!
then when the tubes started to conduct the B+ dropped out. As it turned out when i ordered the parts i needed i inadvertently ordered 22.1 ohm 1w resistors instead of 22.1k resistors. Lesson learned is that when i did the resistance check i missed the fact that it didn't show that little K after the value. I'm a dope.
So i have an order with Mouser, should receive them on monday. I assembled the chassis and took some pics any way.
I still need to fab the brackets that will hold the feet in place, i guess i should focus on that until Monday
Peace Out.
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BTDT. I can commiserate: http://forum.bottlehead.com/index.php?topic=11138.msg102956#msg102956 (http://forum.bottlehead.com/index.php?topic=11138.msg102956#msg102956)
Amp looks awesome though!
cheers, Derek
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Thanks Derek,
It was a nice challenge to design the chassis plates and associated electronics for this project, it seemed to daunting to me to do so
when i built the Fauxplay III, i decided to build a more traditional design. But i have always liked the look of Don Garbers designs and i am sure i will love this preamp once i get it sorted out.
I may have to build a 2a3 or 300b amp in that style to compliment this preamp.
Regards,
Lee.
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The planning and construction journey has ended but the listening experience has just begun.
The correct resistors arrived today and they are installed, it works! and sounds good like a FP3 should!
I'm revealing my inspiration for the first time. I also just noticed that the power trans is mounted crooked, i guess i will have to take that panel off and adjust. Enjoy the pic's
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That's a great work of craftsmanship and imagination. Congratulations
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Thanks for compliment Grufti, but i can't take the credit for the design element. That credit goes to a man by the name of Don Garber.
He built a line of amps and preamps in this style. As far as the circuit the credit goes to Paul Joppa, i merely used different tubes.
Regards,
Lee
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Don would be flattered.
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Thanks PB, I wish had the chance to meet him.
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It turned out great Lee! This topic's been much inspiring for me! It's an A+ on looks for this amp!
Hope it bring's you a lot of perfect listening hours!
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Hey PB, i should also say that i wish that i had met the whole N.Y. Triode mafia. Heady times indeed.