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Another B4 Thread

Ive run mine on 12v for a year and worked perfectly well.
Just changed to a 15v supply dont hear any difference ?
24V is a bit to high

Alan
 
Thanks Alan. I may just use the 14V for a short time, see how it sounds. I was just going to order the traffo, not sure now either a 12-0-12 or a 15-0-15. Decisions decisions!.

Keith
 
337alant said:
Keith,
Get the 15-0-15V, after smothing and regulation you get a nice 15-0-15v with good headroom.
http://rover.ebay.com/rover/1/710-5...0001&campid=5338728743&icep_item=160654750172 , this is expensive buy works very nice and comes with a PCB to mount it on its very quiet and has very low radiated field

Alan
RS or Farnel may sell something similar
Click to expand...

I'd second the 15-0-15 suggestion. It gives you a much wider range of final regulated voltage options. With the very low current requirements of the B4 the standard LM317 / LM337 regulators can handle much larger voltage drops so anywhere between 12V and 18V would be feasible.

PS I tried ordering a PCB mounted transformer from RS when I built my B4 just after Christmas but they were out of stock so had to settle for this instead.

Paul
 
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Thanks Paul. i have the casework to do also at the moment, so i will run the B4 on the test rig at the moment. It will give it time to run in, and for me to swap out input/output caps to taste if required.
Seems like there are lots of different options being used for the input caps, so i will have to wait and see.
I have a account with RS, and the traffo that you used looks like the one.

Thanks Keith
 
Thinking forward to the second B4 build. I have had another look at the build notes, It states that you can use Transistors BD139/140 in position Q2/Q6. I have these in my box of bits. Is there any benefit to this.
I have found also that the legs are to thick for the holes, so it could be a bit of a problem.

Regards Keith.

P.s, Going to the Scalford Show on sunday. Has anyone got a B4 on show ?.
 
What is this Scalford show business? Any DIY stuff from us lot there? I'm not doing anything on Sunday so could go maybe.

Stefan
 
Is there a PFM DIY room? we should sort that our quickl -could well be the best listen of the event!!
 
B4, HackerNAP, Ergo IX speakers, all joined together with DIY leads.... Just need a DIY suitable source - Buffalo Dac and netbook?

Sam
 
sam_cat said:
B4, HackerNAP, Ergo IX speakers, all joined together with DIY leads.... Just need a DIY suitable source - Buffalo Dac and netbook?

Sam
Click to expand...

I could sing down a microphone, but i don't think you would find it very enjoyable. (Sorry)
 
keithsnaim said:
...It states that you can use Transistors BD139/140 in position Q2/Q6. I have these in my box of bits. Is there any benefit to this.
Click to expand...

No point unless you want to drive VERY long leads and use higher voltages when heat dissipation might become an issue with the 550/560 devices. IIRC in previous discussion, PD advised that BC550/560s are quieter and faster...

I built my first prototype with BD139/140s and subsequent boards with BC550/560..can't say I heard any difference.
 
neiljadman said:
No point unless you want to drive VERY long leads and use higher voltages when heat dissipation might become an issue with the 550/560 devices. IIRC in previous discussion, PD advised that BC550/560s are quieter and faster...

I built my first prototype with BD139/140s and subsequent boards with BC550/560..can't say I heard any difference.
Click to expand...

Like the man says!

BD139/140 only needed to drive say over 100m of cable, or if you need to drive matched 75Ohm or 50 Ohm loads, say for video distribution, or for very large signal applications (over say 12Vrms), running off higher voltage rails.

You would have to wack the operating currents up, and alter various resistor values, for the video application.

For audio use, at normal pre-amp levels, BC550/560 are a better choice.
 
It's a tribute to the design that improving the sound quality of the original has been a bit of a struggle. I made mine to close to the original build but with bigger input caps and I've only changed it once. (Input caps) I've been messing with my system and put a cyrus aca7 in place the other day. The life in the sound just wasn't there. Restored a few hours later.

Thanks again.
 
Thanks for all the input. Sam what room are you in?. Is there a list of exhibitors and the room that they are in. I know to at least 4 Pfm members that are showing, looking forward to the day out.

Keith
 
Enjoyed my first visit to the Scalford show. I managed to see most of the rooms, maybe!. I must say that the Pfm lads did us proud. Flatpoply's system sounded really good " well done Andrew.
Next door " Uzinusa ". Now this system i really liked, Ncc200 amps too. Superb!.
Tucked away we came across David " Df_genius'. This system rocked, hackernap power amp, and a very good pre-amp B1 buffer. again Superb.
Well done All. Sorry if i missed someone.

Regards Keith

Almost forgot Si " sq225917 " . Got to his room late on , didn't manage to have a chat due to him being busy with other people. Yet again a very good sound, and the turntable was something else . Nice one Simon.

When i got home i managed to finish the B4 off. Wired it all up now that the input caps have come. Left it turned on for about 1 hour. Checked the voltages with PD's reference and all checked ok. I will try it out in the morning " can't wait ".

Cheers!
 
Ok! so i tried the B4 out this morning. Disaster to say the least. Got a loud earth hum, that can be sorted. The main problem is severe distortion and hardly any volume. Thought it checked out Ok last night.
Can someone point me the right way to check all the voltages again. think i may have missed something major. i have been checking with my DVM all measured with reference to ground. Maybe the CCD's have something to do with it, not sure. i am leaving the probe on ground and moving the other probe around the board measuring at various points. Is there a photo somewhere that shows the different places to put the probes and the readings that you should be getting.
Many thanks for any help given Keith.
 
The only thing I can offer is a probe inside my B4, but that depends on where you are in Yorkshire. A Cumbrian. Otherwise good luck it should be relatively easy to find the problem.
 
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