Juma's LSK Preamp - SMD version

[MASantos]

Tabs are nice!

 

[PKI]

Buzz, how is PSU connected to the amp? External wiring?

 

[tinitus]

I'm just curious

why is it called Juma's LSK preamp ?

is it Juma's BJT version of Nelson's jfet LSK ... 😕

 

[buzzforb]

Just trying to give credit to Juma for his adaptation. I believe Curl was in fact, the first. R electronics is largely an old game from what little I have gathered.

PKI,
I chose wired connectors as routing would get congested otherwise.

 

[BigE]

On the original, there are only two connections for the power from a center tapped transformer, which uses both diode bridges.

Can this implementation use a center tapped transformer as well or do you need to have two independent secondaries?

 

[MASantos]

This needs dual secondaries as each board is one channel.

 

[BigE]

Buzz says there are four connections per board. One channel of Juma's schematic shows two connections with a CT transformer for a single chanel.

 

[buzzforb]

He is correct. I set this up for a dual secondary transformer. It saves 4 caps and allows a dual graetz, which should perform more optimally from a transformer loading perspective.

 

[tome]

Hi Buz.
Put me on list for one stereo set and whatever matched parts you can provide and also SMD parts. I'll solder my SMD parts.
And pls sent me PM when you start collecting payment.
All the best.
Tome.

 

[BigE]

Thank you buzz!

 

[BigE]

Just a question. Have you considered these instead of spades?

[url=http://www.digikey.com/product-search/en?mpart=8730&vendor=36]Keystone[/URL]

 

[buzzforb]

Tabs are more readily available. Plus, screw with no plate is not attractive to me as most transformers do not use solid core wire.

 

[BigE]

I never considered the wire... learning lots of stuff here, Thanks!

 

[hsi68]

Please count me x1 stereo set (pcb + parts).

 

[Queganga]

+1

 

[buzzforb]

Here are some final numbers.

Boards are $35/stereo pair
Parts kit with matched BF862(no Toshiba fets) will be $120(optional).
Presoldered parts included in kit will be $50(optional)
US Shipping is free. International is $20, assuming small flat rate priority box.


I will include final BOM tomorrow as well as a link to the sign up sheet.

 

[Queganga]

As my old Spanish teacher would say, Que Ganga! (what a bargain!)

Thanks for organizing this group buy.

D

 

[BigE]

Parts plus stereo set please! I think i can justify buying a hot air station now!

 

[buzzforb]

Here is the the spreadsheet. Please fill in appropriate fields.

https://docs.google.com/spreadsheet/ccc?key=0Av3k36EKupGAdENoclUxVE41blY1QU5XNVV3cGRteVE&usp=sharing

 

[buzzforb]

updated the spreadsheet link so it will allow access. PLease sign up for options that you are interested in. Board are ordered. Will post final revision.