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GB for DC coupled B1 buffer with shunt PSUs

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#602
woodturner-fran said:
Alan,

would you give us some more details or even photos of how you set it up?

My set of LDRs need a 500k pot, but thats not anywhere in the signal chain, it just controls the current going to either the series or shunt LDRs (as I understand it). Some LDRs are more sensitive and so need much less current for a given resistance, hence some batches need a 100k pot and others a 500k pot with say a 5V supply.

Fran
Click to expand...

Fran,

I will send a pm with details.

Alan
 
#603
cHoc said:
Is it also possible to go outside those values, eg a 50K ALPS??
I can get an 20K ALPS, but at 2 times the cost of a 50K. (different shop, different prices.....)
Click to expand...

Don't. It will work but we don't want such impedance. It will hinder the quality you can attain. In any case if you must, you should make the 220k resistor a 520k one.
 
#604
fingerx said:
Lightspeed volume use 100K opticoupler in series and 100K shunt to GND, somebody said that almost equal to 10K pot. Any changes if I prefer to use Lightspeed?

I saw there are 12V*2 & 15V*2 50VA power transformer can be use, in fact, which one is more suitable?
Click to expand...

No changes if you use the Lightspeed and it is between 10-20k.

2X15V TX is safer for low mains and Vin-Vout margin. Recommended.
 
#605
korben69 said:
Here's modified V3.1 BOM according to your suggestions/wishes :
a) BC550 and 560 alternatives added.
b) BOM Name : DC Coupled B1 Shunt PSU
c) Recommended Caps list : Nichicon added
d) 1N4001 Qty for Mezmerize : 7 units for Mezmerize
e) Rotary Switch for Mezmerize + Pin header for wiring

Nice to read from you 😉
Click to expand...

:up:

P.S. What about inputs / output pins?
 
#606
Yep, input'ouput headers would be really great. See the ones used here:

darwin_1.jpg


I don't know part numbers etc, but I'll email the TPA lads and I'm sure they'll give that info. What is the pin spacing on the current board does anyone know?

More later.
Fran
 
#608
I was in on the failed group buy and I am interested in the new one.
Waiting for a WIKI page, will there be one?
I've tried listing WIKIs but keep getting a request
for name/password? My guess is the WIKIs aren't
functioning yet, since the web site update? 😕
 
#610
🙂
ichiban said:
I was in on the failed group buy and I am interested in the new one.
Waiting for a WIKI page, will there be one?
I've tried listing WIKIs but keep getting a request
for name/password? My guess is the WIKIs aren't
functioning yet, since the web site update? 😕
Click to expand...

I am trying to resurrect a new GB, but want to ensure the boards will fit on the correct parts, as shown in the pics that Sala's posted a few days ago.

I am planning on getting a few boards to start, lettting a few people build them, and if all goes well, order more according to demand. It wont probably be a lightening fast process. I am doing a 'second beta' of what XaudioX had previously done. We need to be sure the new pcb works. One thing I can say, I am not too interested in any changes to the current effort, unless the entire army of DIYaudio guys protest, or Salas.
😉
 
#617
No, no tranny included - sorry forgot to mention that. Have my own already so wasn't thinking of one.

Anyway, Brian at twisted pear has been more than helpful!! The standard seems to be 0.1"/2.54mm spacing, so it woud be a good idea to have that spacing on the PCB if possible. Is that possible?

The connector housing at mouser:

538-22-01-3037
http://ie.mouser.com/Search/Refine.aspx?Keyword=538-22-01-3037

crimp pins:
538-08-50-0114
http://ie.mouser.com/Search/Refine.aspx?Keyword=538-08-50-0114

and the 3 pin headers, first straight:

538-22-28-0030
http://ie.mouser.com/ProductDetail/Molex/22-28-0030/?qs=sGAEpiMZZMukXCIZ6E1E4C9w5F9bxKjZb1W2GGPACeA=

Now, they are Molex KK ones. If you shop around the mouser catalog a bit there are cheaper options and the non-polarised ones are a good bit cheaper, down to about 15c each or so


Fran

Maybe you need a new column in your BOM korben for "optional" components?
 
#619
3rd bit of info:

I got a response back from the ebay fella about the stepped pots. He says he will have 20k ones in about a week or so. I've asked him to email me when he has them.

They are DACT type ones with SMD resistors. I've used either 2 or 3 of them now and they work fine. Maybe not the smoothest ever, but a hell of a lot better than some I have tried on $$ amps. They don't click or pop as you moves through the steps. They feel a little "tight" which is probably good - better than the ones that feel kinda loose and sloppy. Anyway, heres the link to a 10k one he does.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=270438683347

Oh yeah, the cost!! they're $25 + $4 shipping which is about €22 or STG£18

Fran
 
#620
AlanElsdon said:
I am one of those using a Lightspeed as the volume control on a B1 - as soon as these new boards become available I will repeat this setup. One small problem might be that the new matched LDRs are setup for a 500K pot - perhaps Udailey can comment.
Click to expand...

Yeah I can comment. That run of LDRs I did recently did work best with 500k pot to get the desired minimum of 7k input impedance to the LDR based pot you end up making with the LDRs. This new batch I am doing is not telling me enough yet to determine which pot will work best with them. Its not a big deal though. Its just a pot. Whether they need a 1k pot or a 1Meg pot it doesnt matter because its the LDRs that are controlling the B1 and not the pot.
Uriah
 
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