R*E*D Forty Seven

[emrr]

My hope is to try in reverse this fairly large UTC  1 : 7.45  output from the RCA BA73 program amp. With a multi-tester the readings are just under  0.9 ohms and  31 ohms.  I've ran music through these in 7.45:1
step down into a V72 and the result was quite OK.  John, do you think they are likely to work well in this circuit?

It's an old one to respond to, but a BA-73 output is 600 ohms on the high side; far too low to reverse and stick on a tube plate impedance with any success. 

 

[hitchhiker]

thanks Doug, I was thinking that it might be an impedance problem.

 

[college101]

This has to be a great sounding pre amp!! Im considering it for my next build...

 

[letterbeacon]

I see in this thread that the Cinemag CMMI-7C input transformer is preferred for the REDD 47, yet drip uses the Sowter 9970.  Has anyone done any comparisons between the two.

I think when comparing Sowter trannies with the Cinemag CMMI-7C, Sowter was yet to bring out the 9970 which was especially designed for the REDD 47 clones.

 

[ethervalve]

I built a Drip 47 with the Sowters and the Orange 86 project with the Cinemags.
I think they both sound splendid and I honestly can't say that I have a preference (I haven't attempted any objective measurements though).

 

[seavote]

was hoping you guys would get around to this.  but i contacted guitarmaker he is ok with me sharing his layout. he also has a layout for the PSU he used but a lot of members used a modded gyraf G9 PSU.  as for 48V  phantom,phase etc id use this:
http://www.jlmaudio.com/shop/index.php?_a=viewProd&productId=8

 

[JayDubrek]

Just posted the same question where this layout has appeared in Drawing Board ..... that 100mF Elec cap seems to be unconnected on the +ve side...?

 

[daveode]

Correct me if I'm wrong but I believe that 100uf cap is connected parallel to the 200r resistor. So it's pin 3 and 8 of V2 running to a 200r resistor and 100uf cap in parallel to ground.

 

[JayDubrek]

Yeah checked the original schematic and that does seem to be the case...
Has anyone got the layout for the modded G9 PSU used in this?

Cheers
Jay

 

[letterbeacon]

I have a Shinybox 46MXL ribbon mic, does the REDD 47 have enough gain for a ribbon?  Just as I'm getting the parts together for this project, I'm starting to worry that 46dB isn't enough!

 

[college101]

So..what is the breadboard section in the middle of the case "Seavote"? with the three blue caps??

It looks amazing, and Im considering attempting to build this next

 

[JayDubrek]

He's added a regulated supply...

 

[college101]

JayDubrek, Thanks

What is the reason for adding the regulated supply?

 

[college101]

What voltage regulator are you using?  Should have been the question in my last post! 

 

[letterbeacon]

It looks like that's providing phantom power to the XLR in.  The diodes on the bottom right are part of the power supply that's feeding the REDD circuit.

 

[college101]

Yeah..The diodes on the bottom right side are from the power transformer,(which is in the schematics) the Voltage regulator, is not in the schematics, which is what I was referencing

 

[college101]

I can see the yellow wire to going to the input xlr

 

[Potato Cakes]

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

Do you still have the layout for your point to point Redd 47 layout? Could I PM you for it?

Thanks,

Paul

 

[lukas]

...this?

 

[Potato Cakes]

Yes!  Thanks!