Bijou All Tube Futterman Headphone Amplifier - Page 160

Soon I hope. Still waiting on the Ecc99 and the transformer.

I received my parcel from Jeff today..
Just need now to find a new flat and to get my truncks ! All my tools are inside.
Can't wait to hear this "jewel"

That's good news Breizheau! We look forward to your build.

Here is a picture of the first aluminum chips coming off of a volume knob for the Bijou. Assuming I don't switch to stainless steel..........

I will order my trafas when i will be settled.... I asked for customized with 230V primary and 260-0-260 @ 200 mA and 6.3V@4A for secondaries. With covers, the prices are the cheapest i have !!! For 2 pieces made in my country, the price is equal with 1 piece ordered abroad.....
i just have to wait now for my tools.

Very nice @amphead! I had some custom machining done for my Bijou project and the cost was a little pricier than I wanted. I wish I could justify purchasing a lathe. Congrats! When will you start taking orders?

Done. At least for the electronics part for now.

Nice amplifier. It works well with my 6bq7's but I haven't listened to them critically. The chassis ain't pretty, but it was free and provides excellent ventilation. I'll pretty it up later. I certainly won't win any awards for wiring either.

Went to a meet around indy last Saturday. I thought u guys might like to see it since people had some nice things to say about the Bijou. Seems a fair few people listened to it while my eyes were closed.
http://www.head-fi.org/forums/f45/mi...6/#post5541498

PS. Grats on your latest purchase amphead. Looks like you'll be in for some fun.

amphead, nice kit. I'll be in the orders queue when you move on to stainless. It will go well with my new matte black Hammond cases.

whitelabrat, good to see another Bijou up & running. At least its physically contained, unlike mine, which is still an aesthetic nightmare sprawling over a desk in my study three months after fire up!

I'd like to share some notes and impressions about my experience for folks to consider. My goals are, #1 great sound and #2 do it cheap without sacrificing #1.

For folks looking to start a Bijou I can suggest a couple tricks to save some $. For a power transformer try the Allied 6K56VG (alliedelec.com). I ran my build for several hours and everything ran cool and quiet. Getting a regulated 250vdc was no problem with an EZ80 rectifier. It's made by Hammond, but costs less. Also keep an out out for overstock parts. I got three 470uf caps good and cheap. I would expect that even a EZ80 should work with the Regal Mods, but R7 and R8 may need to be changed for the job. The Allied power transformer should have enough of a current rating to force the EZ80 to work. I've not tested this yet though. In any case go with EZ81's whereas I already bought a bunch of EZ80's and want to make them work.

I prefer dumping electrolytics/bypassing from the signal path so I used two pricey (for me) Solen 100uF 400v caps for output coupling which are fine for headphones down to 100 ohms. I've found that a pair of cheap 600uF ASC GLY513 caps work just as well. Go hunting for motor run caps on th' bay.

Alps blue velvet pot vs cheap stepped attenuator? Stepped attenuator wins unless you smash it up like I did.

Negative feedback doesn't seem to help any with 100 ohm or 600 ohm headphones. Am I missing something?

In hindsight I would suggest the Regal Mods. The PCC88 and 6bq7 tubes I've tried seem hungry for more juice. The lows and midrange isn't as aggressive as I would like it in the stock configuration.

Very quiet operation as I would expect from a regulated power supply.

Thoughts for Bijou II: Constant Current Source for V1? I saw something with an opamp in it. Either unregulated PS with LC filter and tube rectifier, or completely solid state PS? How about the TIP50 thing?

I wanted to post a quick followup. I tried the 6bq7's again and it sounded better (to me). I think the PCC88's need more heater voltage which makes sense being that the heaters are rated for 7v.

The 6N1P Morgan Jones amp I cobbled together didn't like the 6bq7 for the input stage (weird tingly noises), but the Bijou seems to like them even though they're very microphonic. Excellent! They're super cheap and I've got tons of 'em.

Question about feedback. How do you know when you've got it right? Subjectively of course.

This is most certainly true. Running the 7V heaters at 6.3V will make the tubes sound pretty lean.

The NFB is entirely subjective, but most listeners do notice it. If you're running 100R or higher headphones the NFB won't make too much difference. It's mostly there for the 32R headphones where you need to decrease the Zo, reduce the distortion, and increase the bandwidth of the amp when it's driving a low Z. This is because the native Zo of the amp is about 55R.

At first it's hard to tell the difference between changing NFB and changing volume, but after some listening most folks have reported changes in the sound stage and other refinements. Some prefer no NFB all the time independent of headphones. If you are sure you'll be using 100R or higher Z phones I would leave it out.

Thanks for the suggestions for Bijou II. If we do another version we'll try to bring in some of the changes suggested by builders. The main change will be a beefier PS so that we can run the input stage and phase splitter at at least 5mA each (regal's changes).

whitelabrat are you also changing cathode resistors when you use the 6bq7s? It's not possible to arbitrarily swap tubes into the input stage of this amp. If you are not changing the cathode resistor then perhaps you could measure the plate voltage of the input triode for both the 6bq7 and the pcc88? This will give us some idea of exactly where the op point is.

Thanks.

A little OT here, but is there a general ranking of Bijou, SOHA II and EHHA? I'm leaning to EHHA because it fits with my plans best, but still wonder if there's a consensus.

I don't think not many people even know aout the EHHA let alone heard it.

runeight,

I've not changed anything from the 6922 stock configuration. I recall somewhere buried in the post that there is enough of a difference between the 6922 and the 6dj8 that some changes may be required. The 6dj8 is an improved 6bq7 if that helps any. I'll try to pry these headphones off my head to make some measurements.

Some humor for folks. An ancient Audio Alchemy DDE v1.1 landed in my house today. It just handed a whoop to my modified E-mu 1212m. Something has to be wrong with that. I'm feeling a bit disillusioned and lovin' it.