SR45 amplifier

[howardnair]

i am getting close to finishing the SR45-am just about to put the soft start boards on-these come with a string of diodes 1n5373B -why this particular diode vs a 4007-i have put some sf4007 in place-- as i was getting ready to solder a little bell went off-i will wait for a answer--here are some pics --the main chassis plate will sandwich between the chassis box and the top-similar to the transformer cover-the transformer cover  will sit right on the top not up off the top - as the pics show
https://picasaweb.google.com/100635555508988591604/Sr4502?authkey=Gv1sRgCLTk_5qar63CYA#5960746136821081762

 

[jrebman]

Hey howie,

Good you asked --  those need to be the supplied zeners, not just basic diodes. You probably saved yourself a good boom!

-- Jim

 

[johnsonad]

You do some beautiful woodworking! Please post picks of the finished amp!

 

[howardnair]

jim thanks-i googled the 5373 a very robust diode--aaron thank you--i wll post a soon as i am finished-which may be postponed --i ordered some 249k resistors for the rca input to ground resistor-they came and i hung them on the wall till i needed them --they are 249R-not 249K

-so that makes me ask how critical is that 249k resistance-i can get close to 249k paralleling something or other-2 475k gives me 237.5 k and so on


since i live on a island-i can't access things like the rest of the world-there is a radio shack here -it caters to cellphones and tv/vcr's etc--
thanks howie

 

[johnsonad]

Paul, how are the new amps coming along?

 

[howardnair]

i am waiting for 2 resistors that were mis-ordered-while i wait i am cking my connections etc-my question is what goes to b- what does not-i have yet to put the slowstart board on as i need to get in there for the resistors i am waiting for-when i put the slowstart bd on 1 wire goes to b- from the board-i have b- from the bottom of the cathode bypasscap--where else do i need to pickup b- ----the places in question are coming from the rca input to a 249k resistor then to b- and/or ground -and at the bottom of the zener diode string-meaning at the other end away from where OA connects with the plate of section 2 of the 6cm7---; the diode string connects to ground do i also pick
up b- -----my star ground will be at the corner of the power trannie --many thanks howie

 

[Paul Joppa]

Paul, how are the new amps coming along?

Sorry I missed this when it was posted.

I got stalled the last few months - partly holidays and other obligations, partly the two power supply circuit boards. But as of this afternoon I have a complete draft of the most intimidating one - sixteen diodes, eight electrolytics, one regulator circuit, two time delay circuits, and two relays on a 9x2.25" board. And two dozen off-board connections. It's pretty crowded...

Right now the plan is to do the second board (basically three more regulators and two C4S's), refine them both, and build a couple prototypes.

 

[johnsonad]

Thank you for the update Paul. 

 

[Paul Joppa]

Aaron, I have to thank you for keeping my nose to the grindstone.

When I first got into this it was through attending VALVE club meetings. Dan - Doc B - always started the meeting by going around the room asking what we had done the last month. The peer pressure kept us all innovating and trying things - it was a really exciting time for us all! Your periodic reminders have the same effect. So thanks!

 

[johnsonad]

Alright my friend, another month has past! Any updates sir?

 

[Paul Joppa]

Sorry, been a slow month with some as-yet-unclear medical problems. I did get most of that second board done, and decided that the final version will likely combine the two boards to make more efficient use of space. Thinking I'll then be able to put in some film caps for the last PSU and the cathode bypass.

 

[johnsonad]

Monthly check in time.  How's the progress sir?

 

[Paul Joppa]

Picked up some parts at Bottlehead HQ on Wednesday, to mock up the power supply.

 

[tsingle999]

Super excited about this amp Paul! Its fun to see the progress updates! Taran

 

[dth31]

THIS is the Bottlehead amp I have been waiting for!

 

[johnsonad]

Paul, forgive me but are these going to be mono blocks or a stereo amp?  I can't remember which way you decided..

 

[Paul Joppa]

Because of the extensive new circuitry, the chassis plate is 10 by 16 inches for a monoblock - somehow I think a 16 by 20 inch chassis would be a little clumsy!

 

[xcortes]

And there's not enough room for my tl 404s!

 

[dth31]

Music to my ears, literally and figuratively!

 

[johnsonad]

What's the word Paul, how goes the build?