[balderon]

Quote:

Originally Posted by rolotube /img/forum/go_quote.gif I've just installed the biggest MCap (330uF/250V) for C5 & it seems to be an improvement over the 200uF Tubecap I've been using for some time. Anyone else tried the big MCap & would it be beneficial to bypass it with a small value HQ film cap. My current thinking is it sounds fantastic without so don't mess with it. I've also read about a so-called "time smear" that can be introduced by paralleling caps in signal circuits. Any thoughts on whether this may be an issue with the Bijou design? Thanks.

I see no need to bypass C5. I am using the 330uF MCap and have bypassed with 0.1uF MCap silver/oil. I love the sound and I did not hear any appreciable difference with or without the bypass. I decided to leave it installed because it helps me know where it is so I don't lose it. LOL Ferrari installed the same MCap and he reported the same observations without the bypass cap. fishski13 has installed a smaller MCap and enjoys the sound. I don't know if it was bypassed.

 

[nattonrice]

I have the same 330uf caps here for that reason... glad someone else did the same.
I have some vcaps lying around that I want to try bypassing with.
I hope (lol) to get time to actually put this together sometime in the next 2 months.

 

[tamu]

Well all my boards and other parts for the amp cannot be delivered as planes cannot fly in to UK.. Very annoying. I cant imagine how annoyed the people who got stuck overseas feel.

 

[rolotube]

balderon & nattonrice, thanks for comments. I'll continue listening without bypass for the present. I couldn't detect much difference with the 200uF Tubecap bypassed (1uF Jupiter) & I suspect the same would be true for the big MCap.

0.1uF Supreme S/O's are real nice for C3 & 4.

 

[mobayrasta]

I have a bone stock Bijou, built by dBel84. There are absolutely no mods done, it is the original build. I have noticed quite a few mods have popped up since the original design. Should I consider these. Which one's should I have done? I love the sound and everything works great. Would I get a significant increase in sound quality with any of them?

Thanks.

Chris

 

[mugdecoffee]

Quote:

Originally Posted by mobayrasta /img/forum/go_quote.gif I have a bone stock Bijou, built by dBel84. There are absolutely no mods done, it is the original build. I have noticed quite a few mods have popped up since the original design. Should I consider these. Which one's should I have done? I love the sound and everything works great. Would I get a significant increase in sound quality with any of them? Thanks. Chris

I noticed a big difference after doing Regal's mod. It's dirt cheap to do since you only change resistors. Its just a bit of a pain to pull out resistors of a populated board. I think most of the other mods are to get rid of noise and aren't necessary if your build is working well already.

 

[mobayrasta]

Yes build is totally silent. Don did an amazing job on this amp!

 

[rolotube]

Quote:

Originally Posted by mobayrasta /img/forum/go_quote.gif I have a bone stock Bijou, built by dBel84. There are absolutely no mods done, it is the original build. I have noticed quite a few mods have popped up since the original design. Should I consider these. Which one's should I have done? I love the sound and everything works great. Would I get a significant increase in sound quality with any of them? Thanks. Chris

I have made all the mods suggested on the official Bijou website (regal, amphead, choke PS, tube rolling, etc) as well as some suggested by Bijou builders on this forum & many of my own. The end result is the best amp I've ever listened to. Whilst these changes have, IMO, been well worthwhile, its has been a lot of work & not come cheaply. No doubt others could also attest to this. But that's the beauty of DIY - you can do as much or as little as you like, whenever you like.

As for improvements in sound quality, most have resulted in a detectable change or improvement. The sum of these is an amp that is, to my ears, significantly better sounding than the stock build. If you wish to pursue with changes, I'd suggest starting with the simple & cheap ones such as regal's & work your way up to things like expensive & exotic output caps (which can pose mounting problems - don't ask me how I know), choke & other PS mods & expensive resistors.

 

[fishski13]

Quote:

Originally Posted by balderon /img/forum/go_quote.gif I see no need to bypass C5. I am using the 330uF MCap and have bypassed with 0.1uF MCap silver/oil. I love the sound and I did not hear any appreciable difference with or without the bypass. I decided to leave it installed because it helps me know where it is so I don't lose it. LOL Ferrari installed the same MCap and he reported the same observations without the bypass cap. fishski13 has installed a smaller MCap and enjoys the sound. I don't know if it was bypassed.

i'm only using 150uF MCaps and bypassed with 0.47uF Sonicaps. the bypass caps could be more or less considered vestigials from an earlier evolutionary age when the output coupling caps were lytics. i probably wouldn't have placed them if using MCaps in the first place.

i'm also not using any NFB. calculating the corner frequency with my K702 impedance of 62ohms, i get roughly a highish 17Hz. you can argue that bass attenuation isn't an issue, but rather it's the phase distortions that affect frequencies up to the mid bass. i can't say i care. for me, the Bijou gives a funky/chunky bass with guts and nuts that works really well with the K702. i think i've said this before, but the K702/Bijou pairing is very reminiscent of the very engaging Naim Audio sonic sig, but without the bright, dry, harshness that their speakers are known for.

i also ripped out my big Electroswitch D9-series attenuator with Dale RN60 resistors and Vishay T2352 nudes. i got sick and tired of trying to turn it - seriously, it was a beast to turn. i replaced it with a 100K PEC pot, shunted with a pair of 100K Vishay T2352. i can't geek-out with a before and after to A/B, but as far i can tell, it sounds just a good.

i'm planning on bringing my Bijou/B22/y2 to CanJam this year.

 

[tamu]

An update on my progress..

I havent received the amp parts from GJA yet but have everything else nearly done

I have also finished building a stepped attenuator for my bijou and I was wondering is it possible to use a stepped attenuator for the NFB as well?
thanks

 

[adamus]

You *need* to mount those dials on the back, it would look 10x better.

as for nfb, dont see why a stepped attenuator wouldnt work, would it make before break, if not you may get some juicy pops.

 

[tamu]

Yeah I will try that too. I thought it would look good with the jack output. Also I will paint the plate in black so it will look much better regardless of having the dials in or out.

About the nfb; I bought a second hand one off ebay. How would I determine whether its make before break or not?

 

[adamus]

when turning see if you see spikes of resistance.

 

[vlb]

Is it a good idea to use one triode for left and one for right channel in the same tube? Pros cons?
I would like to thank you all for this tread, it has helped me a lot.

 

[adamus]

that doesnt happen in the bijou.... all tubes are for one channel. IT does however contain two phases per triode.