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Bijou All Tube Futterman Headphone Amplifier - Page 15

post #211 of 3981
3/18/08 at 1:44pm
Quote:
Originally Posted by exphy View Post
is it just me or does glassjar audio not sell kits anymore?
Still making kits, just out of capacitors (and just got a shipment in now). Please E-mail, or contact me through my website.

JR
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post #212 of 3981
3/18/08 at 7:42pm
Alright more Bijous! I decided to finish mounting the RK27 volume pot today, before going for the power supply test. The pot is mounted on perfboard like Mazuki has done but due to my aircraft aluminum frame sticking out 1 inch, I have to screw it into an oak block that is attached to the frame. A bit of a headache, but will work fine, when all is said and done. Seems like the last 5% of the build goes at a snails pace, but that's just me being overly cautious. I am also going to pull the power supply board off of the chassis again and thoroughly clean the botton with alcohol and triple check everything. The only thing that has me concerned are the mosfets, which deal with lots of High Voltage. No arcy-sparky. ;-)
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post #213 of 3981
3/18/08 at 9:51pm
I think you'll be fine. The Bijou is was one of the easier builds I've done. Just make sure you steer clear of the metal top of the blue Xicon 47uF power supply cap. It carries live voltages.
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post #214 of 3981
3/18/08 at 11:38pm
Quote:
Originally Posted by Mazuki View Post
I think you'll be fine. The Bijou is was one of the easier builds I've done. Just make sure you steer clear of the metal top of the blue Xicon 47uF power supply cap. It carries live voltages.
Not that I was planning on laying my elbow on them, but that is certainly good to know

While waiting for my package from Digikey, I cut, twisted, and mock laid out my wiring. Looks like I'm going to be able to do it pretty much per runeight's original instructions, i.e. no extra terminal strips, just a big bolt for the star ground. The particular teflon wire I have seems to "mold" pretty good, I twisted the pairs and bent it to shape. I ordered some of those cool tie-wrap screw mount thingies and ring terminals from Parts Express too. So, looks like it will still be a few days before I can power mine up.
Probably should have been out in the garage practicing my woodworking instead. I'm still a bit apprehensive about cutting out the square hole for the IEC inlet. But I can always cut another panel I guess. I got an extra board just in case. I haven't glued them yet, just some screws. I have to be able to remove my front panel because my plan is to have a sheet of perforated aluminum slide into a thin dado groove on the top, and the regular aluminum bottom chassis slides in as well. So I think I'll put a couple of blocks in the inside front and use some sharp looking screws, maybe those Kreg square drive pocket screws with integrated washers. Also eyeing those screw-in threaded inserts and then I could use bolts.
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post #215 of 3981
3/19/08 at 2:50am
Thanks for the heads-up Mazuki! Yeah, I treat the whole board area/components as though they are going to bite. Something certainly will if it isn't given the proper consideration. You should not fear the amplifier, but you should think carefully about what you are doing before putting hands on or near anything. Check with the meter and discharge caps as neccessary. Well, I am going to wire the power supply board to the secondaries now and test. :-| Edit: looks like you are getting a nice build together Da_burl!
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post #216 of 3981
3/19/08 at 6:10am
So........I wired up ground wire to the power supply board and then to the star ground point, then 260-0-260vac and 6.3vac. Installed a 2 watt 100k resistor across the output points on the ps board. Then I clipped my meter leads across the resistor and set it to 1000vdc. Powered on with the Bulgin switch doing the honors and.........EZ80 heater lit up, but 8vdc reading on the meter. After a quick expletive, I adjusted P1 and walla voltage climbs to 276 volts and so I back the pot down to 250 volts and it holds steady for 5 minutes and then I power down. Thinking about the mosfets was making me nervous, when I didn't see High Voltage immediately. But you won't get HV with the trim pot fully CCW. So now to finish doing the volume and NFB pot mounting on the chassis. So far things are going well. ;-)

Edit: Da_burl, I would drill a large enough hole in the place where the iec jack goes and then take a medium square file and some elbow grease to cut in your rectangular mounting point. It's almost fool-proof.
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post #217 of 3981
3/19/08 at 8:56am
Quote:
Originally Posted by amphead View Post
So........I wired up ground wire to the power supply board and then to the star ground point, then 260-0-260vac and 6.3vac. Installed a 2 watt 100k resistor across the output points on the ps board. Then I clipped my meter leads across the resistor and set it to 1000vdc. Powered on with the Bulgin switch doing the honors and.........EZ80 heater lit up, but 8vdc reading on the meter. After a quick expletive, I adjusted P1 and walla voltage climbs to 276 volts and so I back the pot down to 250 volts and it holds steady for 5 minutes and then I power down. Thinking about the mosfets was making me nervous, when I didn't see High Voltage immediately. But you won't get HV with the trim pot fully CCW. So now to finish doing the volume and NFB pot mounting on the chassis. So far things are going well. ;-)

Edit: Da_burl, I would drill a large enough hole in the place where the iec jack goes and then take a medium square file and some elbow grease to cut in your rectangular mounting point. It's almost fool-proof.


That's what I was going to do, but then I got the crazy idea to try to flush mount it. So I ordered the screw mount ones with the triangular ears. I would actually need a square hole for the body and a recessed area on the outside surface for the mounting ears. You're right, I can probably do most of it with a drill and a file, but I think I would have to use a router or a good old chisel for the recess.
I have plenty of scrap pieces to practice on, so I might give it a try. If it doesn't work out too well, I will just flat mount it, with the ears on the surface of the panel. It will be on the back at least You probably know how it is to obsess on some little detail that has nothing to do with the actual functionality or sound

On another note, my ebay pots THESE and THESE
are on their way from Hong Kong as we speak! I thought I'd give them a try before laying out real cash for a real DACT or Goldpoint or something. Kinda hoping the SMD ladder pot works out ok, it looks kinda cool.
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post #218 of 3981
3/19/08 at 1:48pm
Quote:
Originally Posted by da_burl View Post
On another note, my ebay pots THESE and THESE
are on their way from Hong Kong as we speak! I thought I'd give them a try before laying out real cash for a real DACT or Goldpoint or something. Kinda hoping the SMD ladder pot works out ok, it looks kinda cool.
You know that first one isn't really made by Alps, right?

I have a couple of the 'fake alps' 100k attenuators and while they work, I don't really recommend them unless you like to hear a loud snap every time you turn the knob. That can be minimized by disassembling the pot and cleaning everything with deoxit or similar, and then applying a good layer of silicone grease. But it's annoying, and it's just a series attenuator anyway.
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post #219 of 3981
3/19/08 at 3:13pm
Quote:
Originally Posted by ericj View Post
You know that first one isn't really made by Alps, right?

I have a couple of the 'fake alps' 100k attenuators and while they work, I don't really recommend them unless you like to hear a loud snap every time you turn the knob. That can be minimized by disassembling the pot and cleaning everything with deoxit or similar, and then applying a good layer of silicone grease. But it's annoying, and it's just a series attenuator anyway.
Yeah, I kinda figured, I remember an old discussion about them.

My first try was getting four of THESE . Spent about nine hrs. putting one together, and although I carefully tested the first step and the next two or so, after that, I went all the way through 3/4 of the way or so before I measured it again. Seems that I must have applied too much heat or something, one whole switch bank is open now, so it's fubar'ed. Haven't taken it apart yet, but I might as well someday to see what I can see. I think I'll start another one and leave it there and put one step and measure each day until it's finished. If I prescribed to the time is money theory, these things are so not worth it!!!
By the time I get all these different fakes, I probably could have just gotten a real one, but I'm a cheap bastid too
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post #220 of 3981
3/19/08 at 4:31pm
Quote:
Originally Posted by da_burl View Post
Yeah, I kinda figured, I remember an old discussion about them.

My first try was getting four of THESE .
Oh man, i wish those had been cheap and widely available 2.5 years ago. Back then, that kit was a lot more expensive.

I got a wild hair and bought the 23 position 4 pole Alps rotary switch from triode electronics and bought resistors for it from mouser. Modified it so that it would straddle regular perfboard.

I spent at least $60 on the whole affair, including shipping and 10-piece minimums on 6-cent resistors. And the time when i lost one of the values and had to order another bag of 10 from mouser all by itself with $5 shipping. And then discovered after i got that value that i'd forgotten to order another value. uuugh.

At the time i meant to put it in my M3, which still lives in a cardboard box (I never settled on an enclosure for it).

I'm using it in my Bijou. It's huge. I feel like a moron for ever building it, but using it is the least worst option at this point.

In case not everybody is following the bijou thread at HW, here's some pics from a few days ago. At this point the last thing to do is star ground. I think I've decided where to put it.




The plan is to paint the mesh flat black and the front, back, and bottom panels in a semi-gloss or satin black. I'll need to do some work on the metal first, as the enclosure is an old Dukane PA speaker enclosure from a school hallway or something.
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post #221 of 3981
3/19/08 at 4:44pm
Ericj - as I said on Headwize: amazingly original case! So much more original than what I had planned. Looks like a keeper! Never mind about the Alps rotary, I bet it'll be great with the Bijou.

Congrats!
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post #222 of 3981
3/19/08 at 8:26pm
Nice work EricJ! Very impressive design. The stainless front is impressive and it would also look good with an exotic hardwood veneer, epoxied to the front panel. Either way, it really kicks up the Bijou design a notch. How does it sound, and what phones are you using?

I am attaching my volume and NFB pots to the chassis tonight.
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post #223 of 3981
3/20/08 at 12:36am
That's stamped aluminum actually. And they didn't bother to finish the edges, either, so I'm going to have to file them down before painting.

I haven't finished building it so I'm not sure how it sounds. I'm using 6n1p-ev and 6n6p, fwiw. And i have ever so many 'phones to choose from, so I'm not sure where I'll start with it.

All i have left is star ground. I could have finished it tonight but i can't find my box of lugs. If i still can't find it tomorrow I'll just buy more. I'm also missing some of the hardware i need to hold the enclosure together - used to be held together with rivets. Using speednuts and screws, except i have the wrong screws, and didn't buy enough speednuts.
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post #224 of 3981
3/20/08 at 1:07am
Quote:
Originally Posted by ericj View Post
And they didn't bother to finish the edges, either, so I'm going to have to file them down before painting.
Nonsense! Sharpen them up and make a cigar cutter out of 'em.
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post #225 of 3981
3/20/08 at 1:38am
EricJ, if I had a slew of headphones to choose, as you do, I would go for your best high impedance set. Higher impedance phones require less NFB = Better Sound. ;-) Edit: My K701s at 64 ohms will require a good bit of NFB.
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