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Bijou All Tube Futterman Headphone Amplifier - Page 94

post #1396 of 3981
9/26/08 at 1:55pm
Very nice, gentlemen. But, along with several other designers (Pete Millett, KG, etc) mayhaps we are proving tubes are still the king, albeit in smaller kingdoms.

I cannot wait to start getting these amps out to meets to shootout with some of these other designs, and get to the crux - why are these kingdoms smaller, and, maybe, they will grow quite a bit.
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post #1397 of 3981
9/26/08 at 3:36pm
pabbi1, after you get your balanced Bijou in working order, you'll have to build a balanced SOHA II.
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post #1398 of 3981
9/26/08 at 5:26pm
Well, I was thinking more Stacker, or whatever it is you are doing with the 'Super Bijou'... but, seriously, we really need you looking at electrostatics. There is someone else in Austin that could use a little collaboration, and, well, the tube could be a 6s4... though Russian (6nxp) tubes would be a real preference - oh, and all are balanced by default... ;-)

Though, I have been eying SOHAII - I do need to build something for my brother in Afghanastan (civvy contractor with the JarHeads), so that is my 2nd favorite read these days.

Doing any transformer coupled designs?
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post #1399 of 3981
9/26/08 at 5:47pm
So I scored a Mullard EZ81 for a decent price off ebay... and maybe this is just placebo but it seems like the detail in the highs and upper mids just opened right up! Does the extra 15 volts or so on the B+ make that much difference?

I've got Electro-harmonix 6922's coming to replace my horribly noisy and microphonic JAN Philips tube in the left channel.
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post #1400 of 3981
9/26/08 at 6:27pm
Quote:
Originally Posted by pabbi1 View Post
Well, I was thinking more Stacker, or whatever it is you are doing with the 'Super Bijou'... but, seriously, we really need you looking at electrostatics. There is someone else in Austin that could use a little collaboration, and, well, the tube could be a 6s4... though Russian (6nxp) tubes would be a real preference - oh, and all are balanced by default... ;-)

Though, I have been eying SOHAII - I do need to build something for my brother in Afghanastan (civvy contractor with the JarHeads), so that is my 2nd favorite read these days.

Doing any transformer coupled designs?
Electrostatics? I thought that there were top of the line diy amps out there already. But I'm listening. What did you have in mind?

Transformer coupled headphone amps or power amps?

Now if you're looking for some very cool power amps I have two of them up my sleeve that I'm just waiting to get around to.
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post #1401 of 3981
9/26/08 at 6:31pm
Quote:
Originally Posted by TimmyMac View Post
So I scored a Mullard EZ81 for a decent price off ebay... and maybe this is just placebo but it seems like the detail in the highs and upper mids just opened right up! Does the extra 15 volts or so on the B+ make that much difference?

I've got Electro-harmonix 6922's coming to replace my horribly noisy and microphonic JAN Philips tube in the left channel.
Many diyers believe that certain changes in the ps make an audio difference. There are some that definitely do because they enable better dynamic operating conditions for the devices. In this case, it's hard for me to know. The pass mosfets might be a little happier with a few more volts on them, but they'll still be regulating to 250V. Thus, the tubes might not see much difference. OTOH, the rectifier is not working as hard. So, I guess I really don't know. At this point, after having designed so many amps that are in wide usage, I just think that everyone hears differently. And that some folks can hear very small effects.
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post #1402 of 3981
9/26/08 at 7:58pm
Quote:
Originally Posted by runeight View Post
Electrostatics? I thought that there were top of the line diy amps out there already. But I'm listening. What did you have in mind?

Transformer coupled headphone amps or power amps?

Now if you're looking for some very cool power amps I have two of them up my sleeve that I'm just waiting to get around to.
HP all the way... a la Pate's 307a for dynamics, though I think the Bijou will get most of the way there.

On the electrostatic side, there is a real problem on the DIY amps. KG has given us the KGSS and BH, but both depend on some obsoleted parts (2sk389, etc), and are really difficult to build. Some commercial designs are older generation, some based on Stax DIY layouts, and with some problems where NOT implemented correctly. But, they all also depend on NOS harder than ever tubes, and new designs, with different (read: more available, like 6s4, or Russian) tubes are one answer.

Just if you happen to be pounding the rubble on the dynamic front, electrostatic DIY can use a boost.
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post #1403 of 3981
9/26/08 at 8:22pm
That is a mighty expensive headphone amplifier. Although I have no possible way to know, I wonder if a less expensive amp can do just as well?

I see on the electrostatics. I thought that the BH had pretty much solved the problem for everyone. How much interest would there be in a new amplifier, maybe a hyrid one? I have, you see, already thought about how to do one of these too.
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post #1404 of 3981
9/26/08 at 8:29pm
Quote:
Originally Posted by runeight View Post
That is a mighty expensive headphone amplifier. Although I have no possible way to know, I wonder if a less expensive amp can do just as well?

I see on the electrostatics. I thought that the BH had pretty much solved the problem for everyone. How much interest would there be in a new amplifier, maybe a hyrid one? I have, you see, already thought about how to do one of these too.
I think there would be a fair amount of interest in a new 'stat amp, especially with the gaining popularity in 'stats. Count me in if you decide to go that route.
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post #1405 of 3981
9/26/08 at 8:31pm
Quote:
Originally Posted by runeight View Post
That is a mighty expensive headphone amplifier. Although I have no possible way to know, I wonder if a less expensive amp can do just as well?

I see on the electrostatics. I thought that the BH had pretty much solved the problem for everyone. How much interest would there be in a new amplifier, maybe a hyrid one? I have, you see, already thought about how to do one of these too.
There are collaborators in Austin that will find this encouraging... maybe a couple of email would be in order. Since there are still excellent production electrostatic phones, and the Stax amps are lacking, there is a LOT of demand for the upper end, ESPECIALLY DIY.
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post #1406 of 3981
9/26/08 at 8:46pm
OK. Let me know who the Austinites are. I might know them already.

I will need the collaborators because I don't own ES headphones and I probably won't buy them for this project. I also would need to input from a few folks on what you performance you want. DC voltage and AC swing and anything else.

Can't guarantee that I can get to this right away because there are other projects in the works right now, but I can begin noodling on the design requirements around what I have in mind.
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post #1407 of 3981
9/27/08 at 1:43am
Quote:
Originally Posted by huskydawg9 View Post
What I meant was when you go balanced and have 2 trannys and 3 more boards in there...you may have to run with the top off.
i should be able to get the casework finished next week. i will check the temp with my Fluke and report back. i'd be suprised if it's as warm as my Krell amp.

chobint,
they're 4-way cable adhesive mounts from the local mega-hardware store.

adamus,
looks great! where did you get those tube "donuts" for the chassis lid?

PACE
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post #1408 of 3981
9/27/08 at 4:39am
Finally I finished wiring all the boards.
That what I have



1 - 5 (CT-240VAC) -> 280v
1 - 2 (CT-240VAC) -> 280v
3 - 4 (6.3VAC-6.3VAC) ->6.7v
B+ - 250v

Leads 1&2 -> 6.7v (ECC99)
Leads 1&3 -> 13.6v (Amperex 8416)

R-core transformer (R0080-036)

Can I live with it, or it's too much?
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post #1409 of 3981
9/27/08 at 6:01am
Miky, I will leave that one for Runeight. I suspect he will need you to bring those in line.

Pabbi, I just finished cutting an opening for the switch/iec block and it is now mounted on the back of the chassis, next to the xformer. Power Supply boards are going to be mounted tomorrow. Edit: after the input and output connectors are installed. Momentum is gaining.
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post #1410 of 3981
9/27/08 at 8:11am
And one more problem. PS gives 250v on 100k test resistor. With both amp boards attached I have only 242-244v. With one board attached (any of two)I have 250v.
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