Bijou All Tube Futterman Headphone Amplifier - Page 142

I think the bijou will hactd to much gain to be honest.

Well, almost finished attaching bottom panel and then a pic.

A little off-topic here, but this is a link for you Fishski. Take a look at the High Octane.

Silvatone Amp Projects

perfect!!!

Balanced vs Unbalanced - Differences

OK...so i fried a transformer (i think i must be the first to ever do this around here in the DIY Forum) and took out one my PS the other week; i have been running unbalanced since then. i have since added some nude Vishays TX2352 in the series resistor of my shunt attenuator in place of the Kiwames, and before that, the RN60s when running balanced.

Balanced
K701 - i loved this combo. the bass was smackingly good, mitigating the top end emphasis of this phone, splitting the quanity difference between the K701 and HD650 perfectly. the K701 can be a pretty dull phone, but not so when balanced. timing was very natural and dynamic, never tight-assed or whitey-tighty. music had a pulse.

a huge cyrstal clear 3D soundscape. you are in the mix. imaging and sound placement very transparent; pin-point i guess? anyway, soundstage geeks will enjoy. very detailed all the way around.

HD650 - much more front-row placement. i guess if i had to say, about as close to unbalanced K701 placement. unfortunately, the bass was waaaay too much in quantity for me for any type of music. as a former double bass player, it sounded grossly overblown, and had no snap whatsoever. it tended to impose itself too much every Hz on up. it worked sometimes with electronica and reggae, but a otherwise a total waste of an excellent phone.

Unbalanced
HD650 + K701 - other than the reduction in bass and soundscape, not a huge night and day difference unbalanced. balanced also had a little more finesse with timing and subtle dynamics. unbalanced has a little more drive and forward momentum.

inserting the nude Vishays in the attenuator changed things up a bit though. i had the balanced 3D soundscaping on the cheap and with a bit more detail as well. there is no overblown bass with the HD650, but the K701 quantity isn't quite what it was when balanced (but still sounds excellent for acoustic recordings). these Vishays are crystal clear, detailed, dynamic, and timbre is spot on. highly recommended if you want to try a shunt pot/attenuator.

i've decided to stay unbalanced and will be starting a DIY chassis next week. i can't stand the thought of more blown rectifiers, transistor, and transformers. i've been working on this amp for 4 months now and would like to wrap it up in the next month. besides, i'm waiting to see what else Runeight has up his sleeves. as it stands right now, my Bijou has never sounded better, but i'm sure the K701 balanced with these new Vishays in place could be better.

Yes, the bass in balanced on hd650 is a bit much (maybe needing some bass control, a la m³, well, except in reverse), but with the hd600 I think it is pretty well blended. Anyone who thinks tube amps are bass shy ('rolled off') needs to hear a Bijou.

it's been years since i've heard the HD600, but i think it would be a wonderful pairing.

yes, the Bijou's got cojones.

If the balanced Bijou is best with K701, that works for me! I really enjoyed it with Pabbi's HD650's, even with the accent on bass. Bottom panel mounted. Pics later, it's a busy day.

My Bijou has nice bass with the K701. I picked up a set of AD2000, and they sound great with the Bijou - very solid bass. In fact, very nice all round.

Pic of the chassis with bottom attached. There will be more points with blocks securing in other areas to get maximum rigidity.

Custom Enclosure

Hello,

I quickly built a Bijou amp kit and made this enclosure to give to my brother as a gift. I thought I would share my pictures, might help others decide how to build their Amp.

The PCB is not exactly layed out to make a good looking amp as designed, so I decided to mount almost all the components on the bottom of the PCB except for the tube sockets, FETs and larger power supply caps. If I was doing it again I might just mount everything on the bottom except the tube sockets, maybe cut a few slots for some convection cooling.

I did the design in Solidworks, first I modeled the PCBs with components and then built the box to make sure it would fit. The bottom is cut from a sold chunk of ABS plastic, 8x8x2 and the top is a plate of 5051 Aluminum that is easy to polish. This is scrap I had available.

The top is on standoffs to tweak it, once finished the standoffs come off and the top plate screws to the bottom in the corners. Yes this is easier when you have your own CNC mill.

Holy crap, that's badass.

SJ, eh? Do you offer your services? I'm in SJ too. I really hate casework, but you make it look so easy.

I was going to topmount the PCBs also, but I decided I didn't want screw holes and it would be easier to take off the cover if it was bottom mounted. I've been languishing trying to figure out how to make the measurements to line up the top and bottom, but whatever I come up with is going to be a hair off somehow. Anyhow, I'm going to mount the PCBs on risers, lifted them up about halfway in the case, and then use angle brackets to air wire the tube sockets. The reason for this is that I'm going to flip one of the PCBs over to get the wire routing that I want (symmetry). To be honest, I think (for me) this would be easier as a point to point instead of PCB.

I am in San Jose. I could do another plastic box, the hardest part was the design and generating the CNC program. One minor detail not obvious in the pictures is the very tall caps stick out the bottom of the box just slightly. I am going to stick rubber feet on the corners so they don't touch. There are holes just for those caps. It would be nice to change the PCBs to accept two shorter caps in parallel instead of these really tall caps. The highest components dictate the size of the enclosure.

It would be possible to use a long standoff and mount the PCBs to the bottom box instead of the top. That would certainly be cleaner but it isn't too bad the way I did it because the standoff threads come up flush to the top of the plate.

I think you are going to do a lot of work by not mounting the tube sockets on the PCBs. When you are thinking about symmetry just cut the wires the same length. I used the same length wires where it matters. I also coaxial wires for the inputs to the POT and then to the PCB inputs.

Nice build Boilerbots! Kudos to using the CNC milling machine. I hope your brother enjoys his new Bijou, when you get it finished.

I found some 2 and 1/4 inch, thick wall aluminum pipe, which has 3/8" walls. It is 1 and 1/2 inch inside diameter. I also found 1 and 1/2 inch aluminum round rod to fill the inside snugly. This will be spun on my drill motor and polished with sandpaper to make some 57mm diameter volume knobs. Cutting with a hacksaw will take a while, but where there is a will there is a way. I always liked oversized aluminum volume knobs on stereo equipment. ;-) Edit: I will be putting a bearing in to the front plate for smooth operation of the volume knobs. There will be the backlit Bijou badge in between the L/R volume knobs. When I finish building the volume knobs, I will put pics with a step by step on a new thread for building them from scratch.

Two 56mm volume knobs almost finished. My access to a metal cutting bandsaw is limited at the moment, so they were hacksawed by hand and then rotated/polished on my drill press. They are looking very nice, but that much sawing gave me some sore hands. ;-)