R*E*D Forty Seven

I was looking at the very interesting "Your mic preamp philosophy" tread at the brewery, and CJ was talking about building a R*E*D. Forthy Seven.

Are there any plans for building this? I have already found the schematic in the Black Marked tread by Winston O'Boogie (but no schematic for the PSU).
I wasn't able to find any PCB layouts. Does these exists?

/Frede

I don't think so. You're more or less on your own on that one..

Jakob E.

Thanks, Jacob. I think I'll try to wire it P2P then.

I have found schematics for the amp and the pad-network:
http://groupdiy.twin-x.com/albums/userpics/10036/REDD47AmpSchem.pdf
http://groupdiy.twin-x.com/albums/userpics/10036/Pre-SetAttenuator.pdf

BUT I can't find any schematic for the HT-regulator circuit. Does anyone have a copy of this? Or maybe a schematic/PCB for a better (or easier) way to make it (maybe with 48v for phantom)?

Btw, what kind of switch is the best one to use for the pad network?

I made it PTP and drew up my layout if anyone wants it. With the Cinemag input tranny that is one amazing sounding pre.

Steve

What transformers you used for output.

Yes, post please the layout.

chrissugar

That sounds great. :thumb: Thanks a lot, guitarmaker
I would really like to see the layout. What output transformer did you use?
Also, do you have any pictures of the pre??


Thanks,
Frede

Here's the layouts I used. Turret board was from Newark.

http://www.pacinfo.com/~sholst/reddamplayout.JPG
http://www.pacinfo.com/~sholst/reddpowerlayout.JPG

Input can be whatever you like. I used the Jensen schem. I can't say enough how I love that Cinemag input transformer. Output was a Sowter. I have to check again but I believe I had them wind their standard 10:1 to be a 7:1. I'll look and see. I'll PM the pictures of it if you want. This was my second DIY project so it's no beauty queen. Sounds awesome though. I like it much better than the Phoenix Audio DRS-1 I had which said a lot to me.

Steve

Thanks Steve! Those are very useful :shock: :thumb:
I would really like to see pictures of the unit. Just PM them to me.

Do you have a url for that Jensen input schematic?
Regarding the Sowter output, please check which one you used.

I'm looking forward to building this.

Once again: Thank you,
Frede

hey this is DIY... we will love your pics and understand the slight imperfections.... pics are GOOOOOOD...send em up.
thanks for your layout info (whoever that was)
I would really like to build one of these!!!!!!!
lookin forward to those pics
later
ts

PS can anyone post a basic parts list for this unit.
what did it cost you to build your 47?
where are these huge trafo's on the PCB available?

Okay, I'm ordering some extra turret boards and tube sockets.

:thumb:

Bear

here's a couple of shots of the preamp:

http://www.pacinfo.com/~sholst/redpic1.jpg
http://www.pacinfo.com/~sholst/rack.jpg

The output is a Sowter 9050 (6:1) wound for 7:1. Their charge for that was pretty reasonable. The input was found here:

http://www.jensen-transformers.com/apps_sc.html

It's their standard microphone preamp input circuit. I made mine before Winston shared his attenuator. I think that would be a great addition.

Steve

Forgot to add that the other little transformer and board is the phantom power. Also, this pre was a great way for me to make use of spare parts kicking around so many of the big electrolytics on the turret board don't need to be so big, etc... :grin:

Steve

OK, I just got off the phone with Mr Boogie and here's what happened to the the board deal ( I hope you don't mind, Winston).

It turns out that a certain company to remain nameless did not approve of the distribution of any said boards with Redd 47 printed on them as well as a certain designer. So the selling party, in order to keep himself out of legal hassles, had to pull the plug on the deal. I offered to help in this matter, so maybe something will happen with this, possibly a re-make of the boards with some slight changes, etc. The selling party is not happy with the outcome and hopes that you understand.

As far as he knows, the shipping charges are still in a paypal account somewhere, so this is not a rip and run type of thing. Winston has been very busy with other important matters, thus the lack of comm.

Hope this clears things up a bit.
The circuit is pretty sparse as far as components are concerned, so a new board could be knocked out quite easily.

cj

Oh, and Arrrrrhhhh, Matey! Tu-be Te-ch.

Thanks for the heads up CJ :thumb:

Steve, I thought you were using a Cinemag on the input?

:shock: Steve, that rack is absolutely great looking! And the preamp inside too! (I like PTP for tube stuff, it just looks right :grin: )

Thanks a lot for sharing this.
I'll start to plan how to building mine this weekend.

(@fazeza: I think the Cinemag is hidden on the back. The other transformator inside is for phantom)

Happy weekend :green:

Thanks for the nice compliments guys :grin: Yes, the input tranny is mounted on the front panel close to the input xlr and switches. The two trannys on the back are the output and phantom. The power tranny hangs off the back side. There's so little going on with this circuit that PTP made a lot of sense to me.

Steve

hey .....just saw the pics you posted..

mannn...you are way to modest...that is one nice "rack o' gear"

and ...YES.... thanks for all the pics/info.

I hope the new PCB thing happens soon....I'd like to try tthis one.

anyway...keep up the great work...
later
ts

[quote author="frede"]
(@fazeza: I think the Cinemag is hidden on the back. The other transformator inside is for phantom)
[/quote]

No, I know that. Apparently as Steve says the input tranny can't be seen in the photo as it's mounted to the inside front panel.

Steve, maybe I misunderstood you. I thought you were using some Jensen for the input tranny. Now I see that you're saying you got the circuit from Jensen, but what make/model input tranny are you using?

I can't find in this thread where you've posted that info...

Sorry for the confusion. The input transformer is Cinemag, output is Sowter. I built my preamp based on the Synthpunk web page which just shows this project as the basic amp. I next went to the Jensen page to look over their schematic collection for an input design. They have a simple schematic showing the input xlr, phase, pad, phantom, etc.. So I followed that schematic to make the input from xlr to the input tranny. If I were to do it again I'd probably make the variable pad in there as well. Seems I use the compressor a lot of the time to fine tune the gain into the recorder.

Steve