jensenmann
Well-known member
Hi folks
This is my first racking job ever done. So I thought it would be worth to share with you. My history is that I was 16 years out of diy electronic ´til I found you guys last year and therefore am a little unexperienced in audio electronic. For learning purpose I was looking for some more advanced projects than 1176 and Gssl (I´ve already done these projects without problems) and found those TBG EQ modules on ebay for a few bucks. This should become my first racking project.
http://groupdiy.twin-x.com/albums/userpics/10024/normal_TBG_EQs1.JPG
http://groupdiy.twin-x.com/albums/userpics/10024/normal_TBG_EQs2.JPG
http://groupdiy.twin-x.com/albums/userpics/10024/normal_TBG_EQs3.JPG
The modules came out of a broadcastboard similar to this one:
http://home.planet.nl/~bloe0678/gailing/gailing.jpg
which was located in a remote recording truck. The schems came barely readable with the Eqs and I decided to try transformer balancing the ins and outs. I chose OEP A262A2E for input and Lundahl5402 for output.
http://groupdiy.twin-x.com/albums/userpics/10024/TBG_EQ0001.pdf
http://www.matt-allison.com/diy/tbg_eq1.jpg
Right after breadboarding I fond out that the signalpath had barely headroom with a 0dBm inputsignal. The circuit runs on +19V which isn´t really much for excessive headroom. Also the outputstage seemed to be a little uncomfortable with the Lundahl out. So I decided to use the OEP trannie reversed for stepdown and add a balancing amp with some gain similar to the one of Kev´s ISA-project to bring some level back. This amp should run on a higher voltage than the EQ circuit for preserving the headroom. Therefore I added a second supplyvoltage to the breadboard PSU, threw the Lundahls out and added the output amps. After some measuring it turned out that I had gained 17dB headroom above 0dBm. What i´m not shure about is the noisefloor. Maybe someone can drop a comment on that?
And this is it now with some wild wiring action inside.
http://www.matt-allison.com/diy/tbg_eq2.jpg
http://www.matt-allison.com/diy/tbg_eq3.jpg
Soundwise is it very nice. It adds some nice artefacts without even using the EQ. It´s like a effect unit. The EQ itself has a nice choice of frequencies from Lomid to Highrange, goodsounding with nice character, but only two frequencies (50HZ + 100Hz) in the LF which is pretty poor (and so is the character when Eqing the LF).
Any way, sound and learningcurve with this box was worth every second I invested and effort I made.
Thanks to you guys
Jens
PS: big thank you to matta for hosting some of my pictures :thumb:
This is my first racking job ever done. So I thought it would be worth to share with you. My history is that I was 16 years out of diy electronic ´til I found you guys last year and therefore am a little unexperienced in audio electronic. For learning purpose I was looking for some more advanced projects than 1176 and Gssl (I´ve already done these projects without problems) and found those TBG EQ modules on ebay for a few bucks. This should become my first racking project.
http://groupdiy.twin-x.com/albums/userpics/10024/normal_TBG_EQs1.JPG
http://groupdiy.twin-x.com/albums/userpics/10024/normal_TBG_EQs2.JPG
http://groupdiy.twin-x.com/albums/userpics/10024/normal_TBG_EQs3.JPG
The modules came out of a broadcastboard similar to this one:
http://home.planet.nl/~bloe0678/gailing/gailing.jpg
which was located in a remote recording truck. The schems came barely readable with the Eqs and I decided to try transformer balancing the ins and outs. I chose OEP A262A2E for input and Lundahl5402 for output.
http://groupdiy.twin-x.com/albums/userpics/10024/TBG_EQ0001.pdf
http://www.matt-allison.com/diy/tbg_eq1.jpg
Right after breadboarding I fond out that the signalpath had barely headroom with a 0dBm inputsignal. The circuit runs on +19V which isn´t really much for excessive headroom. Also the outputstage seemed to be a little uncomfortable with the Lundahl out. So I decided to use the OEP trannie reversed for stepdown and add a balancing amp with some gain similar to the one of Kev´s ISA-project to bring some level back. This amp should run on a higher voltage than the EQ circuit for preserving the headroom. Therefore I added a second supplyvoltage to the breadboard PSU, threw the Lundahls out and added the output amps. After some measuring it turned out that I had gained 17dB headroom above 0dBm. What i´m not shure about is the noisefloor. Maybe someone can drop a comment on that?
And this is it now with some wild wiring action inside.
http://www.matt-allison.com/diy/tbg_eq2.jpg
http://www.matt-allison.com/diy/tbg_eq3.jpg
Soundwise is it very nice. It adds some nice artefacts without even using the EQ. It´s like a effect unit. The EQ itself has a nice choice of frequencies from Lomid to Highrange, goodsounding with nice character, but only two frequencies (50HZ + 100Hz) in the LF which is pretty poor (and so is the character when Eqing the LF).
Any way, sound and learningcurve with this box was worth every second I invested and effort I made.
Thanks to you guys
Jens
PS: big thank you to matta for hosting some of my pictures :thumb:
