SR45 amplifier

debk · 181406

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Offline xcortes

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Reply #300 on: August 13, 2013, 03:46:44 PM
Hey Paul, let's say You give me the right op for 5kband recommendations to use an autoformer and I'll take care of the chassis and layout. I'm buildin three pairs and plan to go fully overboard.

And of course you first have to have a workin thing!

Thanks!
« Last Edit: August 13, 2013, 04:00:57 PM by xcortes »

Xavier Cortes


Offline xcortes

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Reply #301 on: August 13, 2013, 04:14:59 PM
Space enough for three pairs of sr45 with tl 404 :)

Xavier Cortes


Offline Doc B.

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Reply #302 on: August 13, 2013, 04:41:27 PM
You might want to keep those TP tapes farther away from power transformers. A power transformer is sort of a mild version of a tape demagnetized.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline xcortes

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Reply #303 on: August 13, 2013, 05:00:42 PM
Thanks for the advise. I just put them temporarily while I rearrange everything. I knew that they shouldn't be close to the amps but didn't know the reason. The system is not working and don't plan to energize it with the tapes there. They look cool there though don't they?

Xavier Cortes


Offline xcortes

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Reply #304 on: August 13, 2013, 05:03:09 PM
Here's a 404 on top of a SR. Exact same mounting hole positions although maybe stacked perpendicularly ?

Xavier Cortes


Online Paul Joppa

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Reply #305 on: August 14, 2013, 05:00:59 AM
"...Alas, 'tis just as I feared..."

The coil axis is aligned with that of the power transformer. The transformer must be rotated 90 degrees to avoid magnetic hum pickup, so the chassis width would probably need to be increased.

Paul Joppa


Offline xcortes

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Reply #306 on: August 14, 2013, 05:39:34 AM
Well, my return to horns next year will prove to be an interesting one!

Thanks Paul, learned a bunch with this exchange. Won't bother you more on this subject for a few months!

Xavier Cortes


Offline Grainger49

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Reply #307 on: August 14, 2013, 08:12:06 AM
I think Xavier just one-upped my CD cases.

No offense meant or taken, Xavier!  Those are beautiful shelves.  BTW, my Temp Area Engineer job ends the last of August.  Then I will be picked up for another project in 4-8 weeks.



Online Paul Joppa

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Reply #308 on: August 15, 2013, 05:21:46 PM
Here's a sketch of the chassis plate. There are two narrow vertical PC boards between the transformers (right) and tubes (left). The one nearest the vent is the heat sink farm; the other is the capacitor farm. So far I've only laid them out enough to place the mounting holes.

Yesterday I emailed Clark about making some nice bases; hopefully I'll talk to him in person before I go on vacation.

Do understand, these are for the proof-of-concept amps (which will likely end up being my personal amps :^). The final design may or may not be different!

Paul Joppa


Offline xcortes

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Reply #309 on: August 15, 2013, 05:30:20 PM
Thanks for sharing! I thought you had said 12x12 but that's obviously not the case!


Xavier Cortes


Online Paul Joppa

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Reply #310 on: August 15, 2013, 05:48:06 PM
Nah - somewhere I read that there is actual science-type evidence that people like the Golden Ratio (it happens to be very close to 2/3 of an octave so I use that) - so I built this on a 10x16 plate.

Paul Joppa


Offline Jim R.

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Reply #311 on: August 16, 2013, 05:07:28 AM
Paul,

If I'm reading you right you're talking about a simlar orientation as the paramour/paramount but with the signal section all at one end and the power section at the other.  I've recently been playing with the idea of making my rebuild of the sr-45s on a narrow and deep chassis to accomplish the same thing of keeping the psu at one end and the the audio section at the other end -- keeping the noisiest parts away from the sensitive gain stages, the audio signal path as short as possible, etc.  Thinking something like maybe 6" wide and maybe 18"-20" long.  Can't claim originality on that one -- see the audio note kegan and kegeki amps as an example.  Of course this is nothing like a golden ratio but could be a nice alternative to having the entire circuit built around a central power transformer.

Not sure this will work yet, but after I cut out some cardboard templates and arrange iron and caps on them, then I'll have a much better idea, but so far, just juggling this stuff in my head it not only looks possible but also that it could easily accomodate a really large pf cap and large ps caps and provide a nice quiet place to mount grid chokes.

-- 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 2wo

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Reply #312 on: August 16, 2013, 05:55:32 PM
I built my SR-45 on a 10"X18" base as a stereo amp. Plenty of room. I think there is like, 12 bits of iron infesting it at moment...John 

John S.


Offline johnsonad

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Reply #313 on: August 25, 2013, 03:52:53 PM
Hi Paul, how is the first build coming along?

Aaron Johnson


Online Paul Joppa

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Reply #314 on: August 25, 2013, 05:10:05 PM
It will be a couple months. I have the chassis plates in hand, and the PC boards about half done - but I'm off very soon on a 6-week vacation to celebrate our 40th anniversary.

On the plus side, Doc B and I conferred Friday for some time to make sure we are in agreement on the design philosophy and direction - I am making a number of technical improvements over our usual practice, almost a new level. Doc B is happy with this experiment, so I have a green light right now.

There will be updates in late October.

Paul Joppa