Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Bijou All Tube Futterman Headphone Amplifier
New Posts  All Forums:Forum Nav:

Bijou All Tube Futterman Headphone Amplifier - Page 7

post #91 of 3977
1/26/08 at 3:00am
Quote:
Originally Posted by regal View Post
Which is the realm of solid state, just my personal preference to keep low Z phones away from tubes. I just don't see the point.
A tube with a transformer is an excellent way to driver low impedance phones, particularly in light of the very benign impedance curve. It turns out that tubes and transformers are very linear devices, much more so than transistors. Transistors require much more work than tubes to make them linear.
Reply
post #92 of 3977
1/26/08 at 4:51am
Quote:
And he'd be wrong. It appears he's looking at the voltages of the circuit without regard to the operating point of the tubes. The 6H30 will work, but it'll be far from optimal and a complete waste of the tube's capabilities.
Roam, you are very talented and your advice will get the respect it deserves alot more with honey than vinegar as Dsavitsk suggests. Dsavitsk is also someone I respect for his knowledge, as he is very often correct.(JMHO)

Where's my Bijou boards? Get in my belly.

Reply
post #93 of 3977
1/26/08 at 6:46pm
Quote:
Originally Posted by amphead View Post
Where's my Bijou boards? Get in my belly.
Big LOL over here, amphead! My wife saw your post and almost spit her coffee out!

I agree. I think we killed Jeff!

On another note, amphead, when you get done with your Bijou, I'll be interested to know your impressions between this amp and the Millet Max. I have a Max board staring at me, but since I opted for a kit for the Bijou from Jeff, it will get done first.
Reply
post #94 of 3977
1/28/08 at 4:02am
My humble apologies Jeff! Checked my mailbox and realized the boards were already there, 48 hours ago. Greased lightning shipping on some beauuuutiful boards. ;-)
Reply
post #95 of 3977
1/28/08 at 4:25am
Quote:
On another note, amphead, when you get done with your Bijou, I'll be interested to know your impressions between this amp and the Millet Max.
Well, I almost know what to expect. The Bijou and the MAX will emphasize different aspects of the frequency response. The Max with its tight Bass and articulate Highs, and the Bijou with pronounced and addictive Mids, giving vocals that sweet and expressive presentation. Of course when I finish my Bijou, there will be a full report. ;-)
Reply
post #96 of 3977
1/31/08 at 2:58am
btw, Thanks Jrossel, I think Alec will enjoy building the Bijou. He wants to use a toroidal. Anyone using a toroidal for the project?
Reply
post #97 of 3977
2/4/08 at 3:58am
Quote:
Originally Posted by dBel84 View Post
much appreciated

toying with the idea of crashing your party on the 22nd, time is a little tight but it would be fun..dB
Wow, I just saw this post tonight. That would be excellent, and we'd be happy to have you be there!
Reply
post #98 of 3977
2/6/08 at 1:19am
Waiting on my tube socket shipment and then, I will start building. Can't wait to hear the Bijou!
Reply
post #99 of 3977
2/8/08 at 2:09am
comments edited.
Reply
post #100 of 3977
2/8/08 at 2:52am
Thread Starter 
He's about, busy as always but getting things done. why not e-mail him, it looks like some communication has gone awry or he has not updated the status posted on headwize..dB
Reply
post #101 of 3977
2/10/08 at 2:37am
A few misc questions. I was going to ask these on headwize but hw wants me to verify my email again, but isn't sending the verification email. I suppose I'm still within the "one or two days" window on email verification there, but golly. I'm not going to wait two days.

Anyhoo. First, tube questions.

I see a lot of 6n6p around the web sold as equivalent to ecc99. Not 6n6p-i, just 6n6p. Are these truly equivalent?

Also, I'm idly wondering if 6n23p is a possible 6dj8 equivalent for this amp. The only potential issue i see is the relatively low maximum plate voltage (100v, 90v for the -ev version). Although I'm more likely to try and use some 6n1p-ev i already have. I'm aware of the filament current requirements.

Lastly, I'm kinda wondering if i can use the pictured transformer with the 220v b+ version of the circuit:

Reply
post #102 of 3977
2/10/08 at 2:11pm
Thread Starter 
Hi Ericj

duncanamps have a link to Franks web site where both pdf's can be downloaded. The tubes are slightly different in spec but similar enough to be interchangeable - unless I missed something in the spec sheet.

The transformer may be a little underpowered for these tubes though = Alex mentioned that the 6n6pi have a different cathode resistance and thus have a higher current requirement than the ec99's - the rated 65mA HV is barely sufficient , I suspect 40mA is a little low but the designer will be able to be more specific in this regard. The heater windings are obviously insufficient.

glad to see you taking this one on and looking forward to comments..dB
Reply
post #103 of 3977
2/10/08 at 2:29pm
i admit that the printing on this trafo is confusing but where are you getting 40ma? the hv secondaries are labeled 50ma, just like the hammond 270ax. there is also that very confusing '0.065a total' marking there.

As for the heater windings, may i draw your attention to the 3.75A heater winding on the lower left.
Reply
post #104 of 3977
2/10/08 at 5:10pm
Quote:
Originally Posted by ericj View Post
i admit that the printing on this trafo is confusing but where are you getting 40ma? the hv secondaries are labeled 50ma, just like the hammond 270ax. there is also that very confusing '0.065a total' marking there.
I would take the "0.065a total" to mean that you can use both of the high voltage secondaries (90 and 235, since they have the * marker) provided the total current draw limit of .065A is not exceeded.

I guess the real question is whether or not it's worth risking ~$40 to find out if does work.
Reply
post #105 of 3977
2/10/08 at 5:21pm
Thread Starter 
my apologies - I somehow read the 0.005 as a 0.004 and completely missed the heater on the left and only saw the measly 600mA on the right. I would still check with Alex re the 50mA and the 6n6p tubes, I recall a discussion that they were not suitable for his build which used the 270AX. The recommended transformer is the 270DAX which has an HV current rating of 90mA. It still seems suitable for the 220V build with the ecc99 original Bijou though. AND this heater supply will not make the tranny run hot ..dB

edit - seems nate's post crossed while a was scouring old e-mail discussions - good poitn re the total HV current supply at 65mA

yet another edit: the psu needs a centre tapped 240-0-240 or 260-0-260
Reply
New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Bijou All Tube Futterman Headphone Amplifier