RE Designs SCPA-1 discussion etc.

nathanm · « **on:** 1 Dec 2004, 07:11 pm »

This will someday be a review of this preamp, but right now I want to right some wrongs; i.e. there haven't been any proper photographs of this unit...until now!

Excessively large JPEG? Yer damn right it is.

----

Okay, time to ease off on the deadly thread-widener. Here's the workingman's version:

If you still want to see the Hero Shots they're here:
http://my.execpc.com/~saruman/temporary_pics/SCPA/

Shamrock Audio · « **Reply #1 on:** 2 Dec 2004, 12:36 am »

I had a hard time getting Dan to stop using US Navy surplus marine grey paint on his gear. I still use the bright orange power indicator on my pre-amp as a night-light.

I think you'll like the SCPA-1 quite a bit. I look forward to reading your comments.

Thanks for the pics! We know Dan's no photographer.

Dan Banquer · « **Reply #2 on:** 2 Dec 2004, 01:54 am »

"I still use the bright orange power indicator on my pre-amp as a night-light."

I have always believed in multi-purpose equipment. Nathan doesn't realize it yet, but behind that LED is a video camera and transmitter so we can broadcast all those kinky things he does in his listening room to everyone here at AC.

d.b.

Marbles · « **Reply #3 on:** 2 Dec 2004, 02:27 am »

At at least one point, it was reported that Dan used steel wire instead of copper or silver.

I wonder why he would do this?

Dan, are you still using steel wire internally?

mgalusha · « **Reply #4 on:** 2 Dec 2004, 03:05 am »

The case looks like it's by Lansing Instruments, I happen to like the way they look.

The SCPA-1 has a very cool lab equipment appearance, I love the vernier dials.

Great pictures Nathan, I wish my photos were as nice.

eico1 · « **Reply #5 on:** 2 Dec 2004, 03:14 am »

Quote from: Marbles

At at least one point, it was reported that Dan used steel wire instead of copper or silver.

I wonder why he would do this...

I hear it's because he's Evil...:)

steve

JoshK · « **Reply #6 on:** 2 Dec 2004, 04:47 am »

I too like the looks. Utilitarian yet sharp and masculine...hu-uh, hu-uh, hu-uh. I dig the dials. You really didn't get that look from the website pictures.

nathanm · « **Reply #7 on:** 2 Dec 2004, 06:05 am »

Shot of the gubbins:

Dan Banquer · « **Reply #8 on:** 2 Dec 2004, 11:42 am »

Yep; The Evil Doctor Steel is using RG 174 and RD 174 as Nathan's picture shows. This is a coax wire that has a copper clad steel center conductor.
The case is by Lansing Instruments and they did the silk screen lettering also
I think Lansing does does a very professional job, and they have been a pleasure to work with.
Please note from the photo Nathan supplied that each channel has it's own separate regulators, also note that each set of regulators are placed at the input of each channel.. Note the copper tape to add ground plane between each deck of six channel attenuator. This helps keep things quiet and lowers crosstalk between each channel. Also note the ground plane that pretty much covers the entire top of the board. Also note the split in the ground plane between each channel, and how it all meets at the unregulated section of the power supply. I would recommend that all of you DIY folks should take note of this board layout.
d.b.

JoshK · « **Reply #9 on:** 2 Dec 2004, 02:41 pm »

What was the rationale behind using copper clad steel wire?

Dan Banquer · « **Reply #10 on:** 2 Dec 2004, 03:06 pm »

There are a few important parameters for wire in this application. Good shield coverage, reasonably low capacitance, and good tensile strength.
The shield coverage for reducing noise and crosstalk in high impedance circuits, reasonably low capacitance to ease the drive capability of source units,(some are robust and some aren't) and the tensile strength so when they soldered to either RCA jacks ot turret terminals they do not break.
Note: I have attempted to magnetize this wire and have totally failed. The copper clad on the steel center conductor appears to be an excellent insulator in this respect.
For more on this subject please find my thread in the Lab section on this forum called "The importance of wire"
d.b.

JoshK · « **Reply #11 on:** 2 Dec 2004, 03:15 pm »

Makes sense.

Shamrock Audio · « **Reply #12 on:** 2 Dec 2004, 07:01 pm »

For the record...

Dan and I go back a few years and there's a reason I've used his gear exclusively for testing and reference. I may harrass him a bit, but that's because I think so highly of him and his products. That said, wood fronts on his amps would help sell them.

nathanm · « **Reply #13 on:** 2 Dec 2004, 07:55 pm »

I've already designed a new faceplate for it in Illustrator. (no, it won't be to everyone's taste but it's damn cool IMO) Whether or not I can actually implement it is another story. Unfortunately it's not just a nice neat flat panel that sticks on the front, but it's this inset jobbie with a lip on it or something. Argh! Sure Dan, make it difficult for me why doncha!

I also think the plastic knob kinda sucks and doesn't quite live up to the coolosity of the trimmers. Oh I know, I saw this cool wooden knob somewhere, coated with top secret military goo and everything. Wait, oh shit - that'll cost more than what I paid for the preamp...dammit!

Guess I'll have to boost some from grannie's old dresser drawer. Much cheaper.

Occam · « **Reply #14 on:** 2 Dec 2004, 08:39 pm »

Dan,

Truly a lovely implementation. I love those locking verniers, makes for excellent repeatabliity as well as being mucho retro and cool.

I think you should top it with a Jacob's Ladder -
http://www.emanator.demon.co.uk/bigclive/jacobs.htm
but it might cause a bit of interference.....

Dan Banquer · « **Reply #15 on:** 2 Dec 2004, 08:43 pm »

Why settle for a Jacob's Ladder when you can go all the way with a Tesla Coil? Thanks for the compliments.
d.b.

mgalusha · « **Reply #16 on:** 3 Dec 2004, 01:07 am »

Nathan,

This is the same chassis with a maple front panel. You can see the edges of panel where it's inset but it wouldn't be hard to make the wood cover them, I just didn't.

nathanm · « **Reply #17 on:** 3 Dec 2004, 03:40 am »

This is what I had in mind:

MaxCast · « **Reply #18 on:** 3 Dec 2004, 04:04 am »

Cool, that looks retro and Jetson's at the same time.

mgalusha · « **Reply #19 on:** 3 Dec 2004, 04:46 am »

Very cool Nathan. I have a friend who does CNC work, if you're interested I'm sure he would like to hear from you. No idea what something like that would cost but he could carve it out of powder coated aluminum with all the designs in place.

He has produced some very nice billet artwork.