SR45 amplifier

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Offline howardnair

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Reply #420 on: December 29, 2013, 02:15:11 PM
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
« Last Edit: December 29, 2013, 02:17:01 PM by howardnair »


Offline Jim R.

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Reply #421 on: December 29, 2013, 02:22:42 PM
Hey howie,

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

-- Jim

Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline johnsonad

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Reply #422 on: December 29, 2013, 02:25:11 PM
You do some beautiful woodworking! Please post picks of the finished amp!

Aaron Johnson

Offline howardnair

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Reply #423 on: December 30, 2013, 01:06:41 PM
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
« Last Edit: December 30, 2013, 03:57:43 PM by howardnair »


Offline johnsonad

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Reply #424 on: January 02, 2014, 07:08:10 AM
Paul, how are the new amps coming along?

Aaron Johnson

Offline howardnair

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Reply #425 on: January 04, 2014, 11:55:33 AM
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
« Last Edit: January 04, 2014, 11:55:31 PM by howardnair »


Offline Paul Joppa

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Reply #426 on: January 18, 2014, 02:19:20 PM
Quote from: johnsonad on January 02, 2014, 07:08:10 AM
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.

Paul Joppa

Offline johnsonad

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Reply #427 on: January 18, 2014, 04:48:46 PM
Thank you for the update Paul.  :)

Aaron Johnson

Offline Paul Joppa

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Reply #428 on: January 18, 2014, 05:14:27 PM
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!

Paul Joppa

Offline johnsonad

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Reply #429 on: February 15, 2014, 03:26:23 PM
Alright my friend, another month has past! Any updates sir?

Aaron Johnson

Offline Paul Joppa

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Reply #430 on: February 15, 2014, 04:00:34 PM
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.

Paul Joppa

Offline johnsonad

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Reply #431 on: March 15, 2014, 01:05:47 PM
Monthly check in time.  How's the progress sir?

Aaron Johnson

Offline Paul Joppa

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Reply #432 on: March 15, 2014, 02:12:13 PM
Picked up some parts at Bottlehead HQ on Wednesday, to mock up the power supply.

Paul Joppa

Offline tsingle999

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Reply #433 on: March 15, 2014, 08:01:13 PM
Super excited about this amp Paul! Its fun to see the progress updates! Taran

SGS iTransporter with Qobuz & Roon to Optical Rendu to BH DAC (Battery) / Wavelegth Cosecant to BeePre to 300b(ehemoths) to Jagers.
Bottlehead Stat headphone amp with Wavelength Brick DAC

Offline dth31

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Reply #434 on: March 16, 2014, 07:05:32 AM
THIS is the Bottlehead amp I have been waiting for!


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