JBB

Redd 47 Mic Preamp
« on: September 19, 2013, 08:10:23 AM »
Redd 47 Mic Preamp





Photos of the project: http://jbb.ru/47/

The scheme used is this: http://jbb.ru/schematics/47-shem.htm

The layout used is this: http://jbb.ru/schematics/47-layout.htm


The original scheme looks like this:




********************************************************************


Accessories purchased in different places:

Transformers Audio: http://www.sowter.co.uk/ 

Resistors and the transformer supply: http://www.partsconnexion.com/ 

Switchman: http://www.hairballaudio.com/shop/index.php?cPath=25

Attenuator: http://www.hairballaudio.com/shop/product_info.php?cPath=27&products_id=65

Case: http://collectivecases.com/redd47.html  - This also fits: http://www.diy-racked.com/diy-talk/viewtopic.php?f=7&t=196

Capacitors and other trifles bought for eBay and Tubedepot.



A few pictures from the field work:

First up was assembled layout of this amplifier:


Potestit layout with different versions of Circuits and correction scheme went on to the final phase:







Audio examples:

http://forum.guitarplayer.ru/index.php?action=dlattach;topic=277266.0;attach=933730

http://forum.guitarplayer.ru/index.php?action=dlattach;topic=277266.0;attach=933731


« Last Edit: March 28, 2016, 07:56:56 AM by JBB »


culteousness1

Re: Redd 47 Mic Preamp
« Reply #1 on: September 19, 2013, 08:42:22 AM »
Not bad as a first post!  :o

Congratulations. Nice build!
Thanks for sharing your layout and supplying audio samples.

Best,
Carsten
"What's all this analog stuff anyhow?" - Bob Pease
"My favorite programming language is ... solder." - Bob Pease

ruffrecords

Re: Redd 47 Mic Preamp
« Reply #2 on: September 20, 2013, 06:01:36 AM »
That is a beautiful piece of construction. So neat. Where did you get the right angle brackets for the tubes or did you make them yourself?

I am always curious about specifications. Did you actually measure the specifications you quoted?

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

JBB

Re: Redd 47 Mic Preamp
« Reply #3 on: September 20, 2013, 10:21:30 AM »
Angle brackets for the Tubes I bought at the local construction market. By radio electronics they have no relationship.



First there was this:





After setting it turned out:




Other settings are the same as stated.


ruffrecords

Re: Redd 47 Mic Preamp
« Reply #4 on: September 20, 2013, 06:41:30 PM »
That's a very nice flat response curve.

What set up did you use to measure the -130dBu equivalent input noise?

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

JBB

Re: Redd 47 Mic Preamp
« Reply #5 on: September 21, 2013, 03:29:55 AM »
I was interested in only two main characteristics of this device.
Frequency Response and Total harmonic distortion.



Total harmonic distortion: (white line)




Moby

Re: Redd 47 Mic Preamp
« Reply #6 on: September 21, 2013, 07:43:17 AM »
Great build. Thanks for sharing the layout :)
For microphone transformers,  BV.8,  Bv.11,  Bv.12, etc.. contact me at mobyelectronics at gmail dot com

JBB

Re: Redd 47 Mic Preamp
« Reply #7 on: September 27, 2013, 12:12:54 PM »
Forgot to warn. To get a flat frequency response, need to remove the C4 and R6. C9 can deliver 10p . The scheme and The layout there are some differences in this place.

blandman74

Re: Redd 47 Mic Preamp
« Reply #8 on: September 28, 2013, 11:40:35 AM »
This is beautiful work.  Could the OPer or someone else suggest a place where one could buy those nice L-brackets for mounting the tube sockets?

I saw this: http://www.groupdiy.com/index.php?topic=47140.0 but those are not quite as sturdy-looking.
« Last Edit: September 28, 2013, 11:44:15 AM by blandman74 »
"Everyday my mind grows keener, my good arm stronger, my silly enemies more futile." KK

JBB

Re: Redd 47 Mic Preamp
« Reply #9 on: September 28, 2013, 04:18:00 PM »
I'll try to find out where it is possible to buy such angle brackets.
How I to find out, be sure to let you know.


Moby

Re: Redd 47 Mic Preamp
« Reply #10 on: September 29, 2013, 05:08:56 AM »
I made similar brackets (sorry no pic) in the local metal work shop. Not a big deal. mine were brass made and they were relatively cheap. 
For microphone transformers,  BV.8,  Bv.11,  Bv.12, etc.. contact me at mobyelectronics at gmail dot com

muffy1975

Re: Redd 47 Mic Preamp
« Reply #11 on: February 08, 2014, 08:16:31 AM »
Hey,

can you detail how and where you added the T attenuate and all the other pots? They are not on your layout.

Michael

müx_micro

Re: Redd 47 Mic Preamp
« Reply #12 on: February 08, 2014, 05:21:19 PM »
Nice one JBB!  :) Very neat layout.

(I have seen similar mounting brackets on ebay. Simply search for noval mounting bracket.)

CJ

Re: Redd 47 Mic Preamp
« Reply #13 on: February 08, 2014, 06:15:59 PM »
bump for the Beatles,   it was 50 years ago today...
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

JBB

Re: Redd 47 Mic Preamp
« Reply #14 on: February 09, 2014, 01:20:58 PM »
I refused to use the attenuator. I use a ribbon microphone. It has very weak output signal. Therefore, I have nothing to regulate.

dandeurloo

Re: Redd 47 Mic Preamp
« Reply #15 on: February 18, 2014, 12:29:41 PM »
Really nice job!
PROFESSIONAL CHASSIS AND FRONT PANELS FOR DIY PROJECTS: WWW.COLLECTIVECASES.COM

Dan Deurloo
www.collectivecases.com
www.risendrums.com

Kingston

Re: Redd 47 Mic Preamp
« Reply #16 on: February 19, 2014, 12:37:52 PM »
Flawless execution. I really like the fact you took the time to present the specs with all the possible details.

Maybe this will set straight the misconception of "tube warmth". THD+N spec and frequency response as shown here is broadcast and even solid state territory and clearly indicates what it was designed for.

PS. I notice you are using some RME product for measurements. It's possible to use RMAA software with 88.2-96khz setting with it. Just set your sound card sample rate from the control panel first, then configure RMAA with the "MME" type drivers. Remember to always set the correct sample rate before starting RMAA software. You will be able to see if the unit is doing funky things above 20khz. :D You can even do 192khz, but there is some low level hash at the very highest "dog" frequencies from the RME card itself to skew the measurement.
« Last Edit: February 19, 2014, 02:24:45 PM by Kingston »

JBB

Re: Redd 47 Mic Preamp
« Reply #17 on: February 20, 2014, 07:34:32 AM »
I was not interested in the results of measurements of THD + N spec and frequency response. I was not going to do them.
This amplifier is initially not the most attractive technical Specifications.
I felt a lack of treble. Therefore was forced to take measurements to determine the cause.
I also did measurements at 96khz, and 192khz. The results were a little more accurate. But, it does not matter.

Re: Redd 47 Mic Preamp
« Reply #18 on: March 28, 2016, 06:15:16 AM »
Hey can you post a layout with the pots and switches on it? It would be very helpful.

ruffrecords

Re: Redd 47 Mic Preamp
« Reply #19 on: March 28, 2016, 06:47:28 AM »
Still puzzled by the quoted -130dBu EIN figure. Did you measure that?

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'