Passive EQ with tube gain make up

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ruffrecords

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I am well on the way to completing the designs of the new versions of my Helios, REDD and Pultec EQs wih built in tube gain make up amplifiers. I have built and tested the Pultec version. It works but there is a small error on the PCB that needs fixing. I have also completed the Helios 69 version and this works fine. Prototype PCBs of these two are in the hands of a small number of DIYers. The REDD EQ PCB has yet to be designed. These PCBs can be used to build stand alone EQs or as pat of an EZTubeMixer or Lunchbox project.

The purpose of this post is set out the basic features  of these three PCBs and act as a focus for support.

1. All PCBs are 100mm tall and 160mm deep (Eurocard size)
2. The EQ in each is identical to the current 3U version which means the hi, mid and lo switches are all Grayhill 71 series types  spaced one inch apart. All other controls are on flying leads.
3.  The PCB is laid out to accept an optional 10K:10K input transformer; either a Sowter 3293 or a Cinemag CMLI­15/15PCA or a Jensen    JT­11P­1HPC so even if you do not use the tube gain make up, you have somewheer to mount an input transformer. Any 10K:10K tranasformer will do but the PCB is only laid out to accept the three types mentioned.
4. A single tube gain make up amplifier is included on the PCB. The circuit is very similar to the poor man's tube gain make up PCB. It has some added links to allow different tube types to be used.
5. An adjustable pad and connections to an EQ in/out switch are included on the PCB.
6. The EZTubeMixer 32 way co.nnector can be fitted is required. The PCB is 100% compaible with the EZTubeMixer design.

Further details, schematics, parts lists etc will be included in the documentation which will be in the EQWithGainMakeUp folder of the DIY tab of my web site:

Cheers

Ian
http://www.customtubeconsoles.com/diy
 

zamproject

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May 11, 2010
Messages
1,235
Hi Ian

Your job since few years now designing modular tube console is absolutely great.
Every time I see post/announcement around your work I feel ashamed to not build a 8x2 tube desk
One day...

Best regards
Zam
 

ruffrecords

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I have already had several emails asking when the documentation will be complete. it will be a little while yet. Fortunately the EQ docs I should be able to more or less cut and paste from the existing docs. In the meantime I have started a detailed explanation of the gain make up stage and its options. Draft attached.

Cheers

Ian
 

Attachments

  • EQWithGainMakeUpdraft23rdjune2016.pdf
    664 KB · Views: 35

ruffrecords

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Location
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Issue 0.2 of the documentation for this project has now been uploaded to my web site. It is in the DIY section of the web site:

http://www.customtubeconsoles.com/diy

in the EQWithGainMakeUp folder. I have attached a copy to this post. It covers the Pultec and Helios EQ versions. The REDD EQ PCB is still under development.  Let me know of any errors or omissions.

Cheers

ian
 

Attachments

  • EQWithGainMakeUpIss0.2.pdf
    1.1 MB · Views: 26

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