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Bijou All Tube Futterman Headphone Amplifier - Page 266

post #3976 of 4179

 

Quote:
Originally Posted by getintechtom View Post

Hi guys,

I'm purchasing a Bijou from a fellow member and would like to know what needs to be done to be able to switch from ECC99's to 12BH7 power tubes.

There's more of a variety of 12BH7's (as well as other models) to go through some tube rolling. I know some rewiring needs to be done on the heater elements.

 

Any info would be appreciated.

 

Thanks

Thomas


Hey there, Thomas, 

 

For starters, you should read up at the designer's site about the Bijou if you haven't already.  That is here.  

 

However, regarding moving to 12XXX tubes Alex says, 

 

"...WARNING: Do not use tubes which have a heater tap on pin 9. This includes all of the popular 12XXX series tubes. The Bijou amplifier board has pin 9, the internal shield in the 6922, grounded to reduce noise. Using tubes with a heater tap at pin 9 will damage the heater biasing circuit and, possibly, cause other problems."
 
Might be more work that you are expecting.  Good luck.  Be safe!
 

Edited by bhjazz - 1/28/12 at 11:08pm
post #3977 of 4179

Oh noes! I have pretty much all of the parts ordered already an now i get to know the amp doesn't do that well with Grados :[

 

What do I do now? Should have gone with EHHA?

 

The new HD700s look nice, how would Bijou do with 150ohm phones?

 

Edit: Solution; get Beyerdynamic Tesla1 and finish the project like a boss! Pictures when it's ready! Could take months thoughtongue.gif


Edited by Kirnupiima - 2/14/12 at 7:58am
post #3978 of 4179

Ivé built my bijou as dual mono with 2 hammond 370 daz.

Ive done regals mods, increased size of caps in the audio circut and replaced elyts with film caps.

Ivé also removed the cathode bypas caps and done regals mod.

 

I know Im only using half of the aviable current from the PS, so the question  is what I should du with the remaining power. I thought of using paralell ecc99s in the output stage to lower zout, but I dont think it makes sense since Im using it as a preamp most of the time, or does it?

 

Right know Im considering a pretty hot biased 6n30p input stage, but I know  that I will loose gain, and right now I like the amp with full nfb wich barely gives me any gain. Maybe an extra gain stage would do the trick? But I gues I have to add 2 stages if I want to keep the global nfb(?).

 

Maybe its a better idea to increase gain på loading the 6n30p with a constant current source?

 

Is there any other tubes I could try as output tubes? Already tried 6n6p but didn´t like it.

 

 

Im thankfull for any comments on my thoughts and suggestions for mods.

 

 

post #3979 of 4179

Hi all, i dont have much experience with electrical stuff although I DIY my own bijou. I have a lcd-2 with me and i understand OTL would not drive low imp to full potential.

 

But i'd like to know whats the power output of bijou at its default configuration? I've tried searching on this forum but did not find anything on output power.

post #3980 of 4179
Hello everyone!! It took me 2 days but I have finished lurking all 266 pages of this thread.

Let me give you some background on me... I am in the navy and have gone through school for micro miniature electronic repair (m2) I am savvy as far as building one of these goes...

I am very new to the hifi world. I was completely content with an iPod and Bose headphones till my friend decided it would be a good idea to ruin it all by showing me a Cowon d2 with a fiio e11 on ath-m50... Ruined me forever! Now I want to build one of these!

Can you tell me if this kit is going to be good enough right out of the box or will I want to upgrade it as soon as I turn it on... Can you give me a list of the easiest and most affordable upgrades. I am already planning on using a 370dax and still looking for everything please help this newb to hifi with some advise! Thanks in advance!
post #3981 of 4179

I understand that you are new in this. Nobody can tell you if something sounds good enough for you. If someone is really sure something is good enough for you, be very skeptical. HiFi is not like computers where someone can objectively tells you that this processor is better than the other one. Let your ears lead you, not some random dude's random opinion. But ironically in youth dominated forums like this it is the newbies who have the most to say.

 

My advice is try to have a listen at the gears yourself if you can, even if you can't listen to everything out there, by referencing with those that you have heard, you *might* be able to guess how the others sound like.

post #3982 of 4179

Hi guys, don't know if this thread is dead or not, but I'll give it a try.

 

I've read through all the pages, and although I've found answers to most of my questions, I still have some:

 

1. Is it possible to use Bijou without volume pot? (I'm going to attenuate digitally via Buffalo II).

2. Earlier in the thread someone was saying that one should turn on\off the amp with the headphones unplugged. Is it just an extra precaution, and not really necessary?

3. I'm going to use Thunderpants with the Bijou, has anyone tried them or T50rp's? They're 50 Ohm, and it seems that low Z headphones are less preferred, but I can attenuate the NFB to better suit them, right?

 

Thanks,

Fedor

post #3983 of 4179

I can answer #2 because I recently had a bad experience with it.

 

During power up, the output capacitor is not charged, and during the 30 seconds or so before it stabilizes, there is DC in the output approx. 60 volts.  This is bad.  If you have headphones connected, they might not immediately burn, but eventually, it will.  

 

At power down, the same thing happens again - but now the cap is discharging.

 

Note that this happens on all equipment with an output cap, but this is specially noticeable with high voltage tubes.  I tried it with only an MKP film output cap by removing the electrolytic output cap, it still registers the DC at power up.

 

In my case, I connected the Bijou to a Pass F5 clone amp, and I noticed at power up a wailing hum from the speakers.  Thats when I found out about the DC when I measured it.  Before I found this out, I always had my HD650s connected during power up/down.

 

So if you have expensive cans, dont do it!

post #3984 of 4179

Thanks for sharing Walangalam, that's pretty bad indeed. I'll need to remember to unplug the phones then.

post #3985 of 4179

I can speak to your last question, as I have a Bijou (much modified) and mod'ed T50RP's. Bottom line is that the Bijou really does its best work with high-impedence 'phones like the Senn. HD6XX. It will

drive the T50's, but there are other DIY amps that will sound better with them. The Cavalli EHHA to name one.

post #3986 of 4179

Hi Funch, thanks for reply. Yes, I know now that Senns are the best match for the Bijou, but I have ordered the kit and trafos just after reading first few pages of this thread, not knowing about which HP's is better matched. And now it's too late to go for another build as trafos and kit (thanks Jeff!) just arrived.

Looks like I will have to buy myself HD650 sooner or later :) But EHHA is on the list too.

 

So I guess only Runeight can answer my first question :)

post #3987 of 4179

Do not regret buying & building the Bijou.  It is an excellent amp and my favorite among the amps I have built or owned. 

post #3988 of 4179

Oberst, I've always wanted to build an all tube amp, and I'm sure I won't regret building the Bijou, I'll just have to do a little headphone rolling :)

post #3989 of 4179

Can someone point me to the page on this thread where the Bijou and the EHHA are compared?  Thx.

post #3990 of 4179

preproman, you can use this wonderful tool for searching - http://headfi.qix.it/, this thread is at the bottom. 

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