Bijou All Tube Futterman Headphone Amplifier - Page 138

If I may,

I have heard two b22, one balanced, and will state, unequivocably, that the balanced Bijou gives the b22 a run for it's money in detail, intended or not, but it is superior in mid band tonal reproduction, especially on voice and strings. The Bijou's sound staging absolutely whips the b22 without any question.

We will put this all to the test in January, as the balanced b22, balanced Bijou, and Pete Millet's 307a (SE) will be in attendance (along with some others, like maybe a Zana Deux, and some Singlepowers) in Dallas, with some really seasoned listeners / MOTs, where I think this all ultimately comes down to personal taste, and what the user wants to hear.

It would also be an honor to have the designer come hear it for himself, as well as the other offerings - the chance to chinwag with Pete is worth the price of admission.

Tempering expectations is one thing, but the Bijou can be built to perform within a few % of the top amps available in the market, and Super Bijou may well place it at even par.

Do not shrink the design accomplishment. It speaks for itself, and can be mentioned in the conversation with any amp. No question it can stand against any other all tube amp, at least from what I have heard. And, after owning 20 amps or so, my experience is that all amps have strengths and weakness - finding the right tradeoff is the goal of the quest, and, no one amp can do everything (hence why I have 3, and am building a fourth).

SS may be technical, but tubes are magic - and we can all use a bit of magic these days.

Who says there ain't no Santa Claus?

PS: I have built a few of Ti's designs, and he IS a truly talented designer - this is in NO WAY reflective of the relative designers - and, in fact, wish 'the designers' collaborated a bit more than they do now. Competition is a driving force, but sharing ideas is a far more powerful tool.

pabbi, just wait till you hear the Stacker 2. Mine died but the brief time I had it going it was like taking the best parts of the B22 and the Bijou in combination.

I think you hit it right on the head. I think the Bijou and B22 are at the top of their class respectively. That is they are the "best", or at least most popular, of the well supported and kit-available pure-tube (minus regs) and SS projects. While it may be unfair to compare the two, such a comparison is implicit in trying to get the best out of your DIY experience. I asked myself the same question before starting..."bijou vs b22" and decided I wanted to see what all that toob magic was about

edit: ya the stacker II does look sexy

Somebody wake me up.

Seriously, we have been asking for updates on the Stacker II thread for 3 months... maybe someone can comment there? And, within the context of a balanced build.

Oh, and I'd also like to raise the question of Super Bijou - if it is not for open forum, someone please PM me, even though I have other (electrostatic) fish to fry for the next 60 days, or so.

Right . . .

Both amps are in progress right now. Both are undergoing revisions for various problems in the proto builds. Which is one reason that regal's died. The Super Bijou needed part of its PS completely redesigned.

Progress on both has been a bit slow due to several factors in the proto groups that are not related to diy, but are just life issues that some folks have been contending with for a while.

Neither amp is ready for open forum at the moment. But, maybe in a couple of months. By then I may have an interesting build to show too.

Super Bijou????

Man, I'm falling behind on projects, better kick my butt in gear...I'll never be able to catch up at this rate.

Next year should prove to be interesting, with a couple of high end designs coming out (from what it appears is stated by runeight).

Yes, there is some Voodoo going on that has yet to be discovered. There are some builds that don't require the ground mod, however I think I'm seeing that nearly 50% of the builds are in need of the ground mod to get the background black. The performance doesn't seem to suffer doing it, so I recommend that new builders do it if they want to eliminate the possibility of a hassle. It is very inexpensive to do because of just the 2 resistors being required. Any wiring scheme other than strictly parallel wiring of the heaters doesn't work with it. No series-parallel, no daisy chaining etc. I'm guessing that's because of symmetry needed for the phase/noise cancelling of each twisted wire, with the "zero" point being where the resistors are tied to star ground, but that statement is more Voodoo, unless an engineer can verify that logic.

you mode is creating a CT, its common practice to do this on power valve amps, same principles apply. A lot fo people will use a hum pot - which was more applicable when resistors werent so precise.

what's the purpose of the heater biasing scheme? haven't built mine yet, still working on component layout.

Holland, that is a technique listed on Alex's website. It is for the purpose of eliminating noise, when it becomes necessary.

Holland.

there is a potential difference between heater and cathode, this scheme biases the heaters to 40v, look at the schematic, there is a voltage divider with B+, but its not a close circuit so no current flows from the B+, it just superimposes 40v dc on the 6.3v wave.

Often not needed, but in this schematic, the upper triode section's cathode is elevated to (if i remember correctly..) 100v ish.

This reduces the pd and prevents hum, and if you look at the tube datasheets, a max heater cathode voltage rating is prescribed, this helps keep that in check.

Adamus is right on this feature. The HK voltages for the tubes have maximum values. For example, the 6922's cathode can be a maximum of 135V positive with respect to the heater. The ECC99, IIRC, is about 200V.

The cathode of the phase splitter is at 100V. The cathode of the top ECC99 triode is 125V. Both of these are within spec but I thought it was a bit safer to relieve some of this voltage difference, especially on the 6922 which is only 35V from its max. So I DC biased the heater supply to +40V reducing the 6922's HK voltage down to 60V. It is not absolutely necessary to do this, which is why amphead's mod works ok. It was an engineering choice to try to minimize any potential problems.

i dont think i posted photos with the final touches....

again, thanks to alex.

Wow, it's taken me a couple days to read this thread!

I'm prepping to build a Bijou, but I'm stumped on some of the parts from the BOM. For example, the heat sink. I'll likely source most of the parts from Mouser. Help?

I've already got an Allied 6K65VG power transformer that is 540vct at 120ma. I've also got a pair of 100uF Solen's and a pair of gigantic ASC 600uF caps that may be used on the outputs. Whatever doesn't get used on the HA2 clone I'm building too.

I'm planning to use 6N1P-VI and 6N6Pi tubes cause I've got them. I've ordered EZ80's but it seems that EZ81's are the preferred option. I've also got 6bq7a's that would be nice, but are terribly microphonic, and have a weird hf ringing to them.

I'll be using Enymotic Research er4s (100ohm) and AKG 240M (600ohm) headphones so far.

whitelabrat, TO-220 heatsinks from at least 1.5" high, available at Mouser under part number 532-513102B25 (for example) should be fine.