Iron Pre

Well ,it started as solution for two customers; both having my Babelfish amps, both driving Dynaudio Contour 1.3 with them.

Whatever solution they had for preamplifier in that time, they weren’t on par with amp quality ….. so logical development of situation is to mate  amps with line stage simple enough but not simpler than necessary …… simply put -preamp made in same manner.

After some chat , consensus was that “plain” buffer (so , no gain ) is adequate,so I decided to make a quick mockup with buffer pcb I had from yore,as part of Poor Serbian Man Lightspeed project.

Frankly – not “plain” buffer anymore , but I simply couldn’t go with less .

Basically-4 separate buffer cells , and simple but witty bipolar (+/-12V) shunt reg on board.Cells are made of scarce and expensive Toshiba JFets (2SJ74BL , 2SK170BL) as source follower. In this case , just two buffer cells are populated, as not needed more for unbalanced operation. For more details, it’s easy to check my signature on diyaudio.com .

Schematic sketch and first proto , conveniently put in dreky casset deck case :

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Book : Harley and me , by Bernadette Murphy

What can I say …..

For almost 3 decades I’m always carrying same 2 books with me , when going on any sort of vacation  – Zen and the Art of Motorcycle Maintenance and Poetry of Stéphane Mallarmé .

Nowadays , things are much easier – take any sort of modern (pocket) gadget with at least semi decent sized screen , and you’re good to have dozens of books whenever you want …… and I’m really digging that in my (hopefully) mid-life age , having no less than few dozens of books in my phone.

So , I read Harley and me , from phone screen,in two evenings during pretty busy week .

It reminds me of Zen , which is good – book as excerpt from someone’s life , brought in decent and honest form and style …… not bigger than life itself, which is first conditio sine qua non for any thing I could possibly be interested in,in my tender age of 49 😉 .

So , go buy it , read it . It’s that good.

‘Nuff said.

http://www.bernadette-murphy.com/

 

Harley and me

Bernadette Murphy

 

And , yes, as would R.P. say …

…… It’s not very factual on motorcycles……

smesna

 

 

Pass Labs X150.5 , checking/adjusting offsets ,Iq and gain

Well , here and there these questions are popping on Diyaudio.com – how to check/adjust bias (Iq) ,offset(s) and gain on my X(A)xxx.? PL amplifier; this tutorial will address that.

Take in account that older PL amps are having (small) mosfet based output stage biasing generator , while later ones are having TL431 generator iteration – with some specimens finished without NTC compensation – exactly as amp shown in pictures.

However, I’m sure that you’ll find same logic (shown here) applicable also to earlier models.If not ,and you need some info regarding earlier models, contact me either through blog e-mail thingie , or on diyaudio.com.

Amplifier shown here is X150.5 , late issue (circa 2007 , according to pcb text) , being in possession of DiyA fella known under witty Old’n’Cranky moniker.

X150.5 front

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Babelfish J , v2

As any named Babelfish – my iteration of Papa’s gadget .

This one is iteration of Aleph J , v2 means made as adaptive base for making almost entire power range of Aleph amplifiers .

Naturally – JFet input , cascoded to prevent poof from excessive rail voltage , additional Daughter boards for additional output mosfets.

More info here .

 

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Blast from the past ……. Iskra EK2304 Cinema Monoblocks – rejuvenation

Some text goes here ……. later

 

I’ll enclose schematics – as it was and as it is now

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