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B4 Buffer PCB (and parts) new GB #3?

Thanks. No pics available but to clarify -
1. The 240v power supply earth is grounded to casing
2. The 0v from the PSU is also connected to casing (Should this go to the centre of the B4 borad?)
3. The Ground from the signal OUT goes to to the RCA outlets
4. The Ground from the signal IN RCA sockets goes to the Grnd at the signal input point.
5. I have connected the ground from the B4 (Central Point) to the casing also.
 
locky said:
Thanks. No pics available but to clarify -
1. The 240v power supply earth is grounded to casing
2. The 0v from the PSU is also connected to casing (Should this go to the centre of the B4 borad?)
3. The Ground from the signal OUT goes to to the RCA outlets
4. The Ground from the signal IN RCA sockets goes to the Grnd at the signal input point.
5. I have connected the ground from the B4 (Central Point) to the casing also.
Click to expand...

Okey dokey, 0v from the PSU needs to go to the centre of the B4 board [signal ground] & remove the ground connection between B4 board & the chassis.
 
Just to say the 1N5287's have arrived from Surplus Electronics in Ohio. Total cost was $21.41 for 40 [forty] delivered to the UK in 9 days with no import fee's.

... Definitely the cheapest source I think, so if you need some don't hesitate to buy from them.
 
istari_knight said:
Just to say the 1N5287's have arrived from Surplus Electronics in Ohio. Total cost was $21.41 for 40 [forty] delivered to the UK in 9 days with no import fee's.

... Definitely the cheapest source I think, so if you need some don't hesitate to buy from them.
Click to expand...

That's a nice price. Do you need all of them? If you have 4 to sell on I'd be interested....
 
istari_knight said:
Just to say the 1N5287's have arrived from Surplus Electronics in Ohio. Total cost was $21.41 for 40 [forty] delivered to the UK in 9 days with no import fee's.

... Definitely the cheapest source I think, so if you need some don't hesitate to buy from them.
Click to expand...

I cannot find the 1N5287 at the mentioned shop. Already finished stock?
 
Can someone clarify that R3, R4, R103, R104 should be 1k8? The BOM and schematic state they should, but the Mouser link for these resistors on BOM is for 18k.
 
Definitely 1k8 not 18K.

The front pair (Q1 and Q4) of transistors run at about 0.5mA, so you get a bit less than a volt dropped across R3 or R4. The Base Emitter voltage drops of Q1 and Q5 roughly cancel, so you end up with about 25 times more current in the output path, roughly 12mA. Actually , Vbe for Q1 is a bit less than for Q5, becuase of the lower current, so it works out at 10mA.
 
Finally managed to get the B4 sorted, having had some issues with feedback and pops for some time. Re-soldered the transistors and the input caps and everything is working fine now. If you have a few teething problems then do persevere. It's worth it! Running mine with Mundorf Supreme outlet caps and Ampfion caps at the input stage. Many thanks to Neil and all those who've given advice along the way...
 
Finally managed to get this one working ! I replaced the CCD's & suddenly all voltages returned to what they should be... Just having a listen now :)
 
I'm very impressed ! Its not even in a chassis and is wired up with croc clips but its got better & better all evening.

Initially I couldnt hear a jot of difference between the B4 & my Alps Blue passive pre but now ? Holy moley its made my very modest setup sound expensive :D
 
Hmm well its been running in for a couple of days...

It sounds pleasant enough, good detail & not offensive in any way but I'm finding it lacking dynamically - It sounds squashed or sat on if you know what I mean ? Anyone else found this or could it be my choice of coupling caps ? [Jantzen crosscap.]

I'm using it with a Nap 140 clone that usually has a real bite to it [which I like] but thats vanished with addition of the B4.
 
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