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Feeler: 553 Style EQ add-on board for TAC Scorpion

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Potato Cakes

Well-known member
Joined
Jul 1, 2014
Messages
2,258
Location
Nashville, TN
Hello,

Currently I am working with a designer to develop small daughter boards to replace the EQ section in the S3301 TAC Scorpion bus channel. It is essentially a 553 circuit minus the output transformer. The 22k center detent pots from the main board will be used (unless they need to be replaced) by removing them and fitting them to the new board to keep build costs down. The PCB will install inverted with the components sandwiched between the new PCB and the main board and mounted to the faceplate by the potentiometers via the original band control drill holes. The EQ switch on the main board will remain in place and be utilized for circuit bypass. The board will also have an extended tab to give access to change the 2520 style op amps without removing the entire PCB. Drill holes for mounting the inductors from CAPI will be included. Other less expensive inductors can be used but an improvised mounting option might be required.

The board could also be used as a standalone circuit or added to another design if so desired but the builder will be required to know how to read a schematic and add the minimal missing parts to complete the circuit. Boards will be no bigger than 4"x3.5" so they will easily fit in many other applications other than the S3301 channel.

The boards will be tested to function in their intended role to verify they do work before being made available. It will be an easy board and a simple schematic to follow but will require the person building to have all the skills necessary to navigate these and a BOM since this will be board only with directions for main to daughter board connections. Most of this should be self explanatory for any medium level experienced builder.

All that being said, I am having at least 16 boards made for myself and depending on what the price break is for manufacturing, I will/can have more made if people are interested. I do not know what the cost will be at this point, but it should be relatively low.

Please respond with interest and/or questions.

Thanks!

Paul
 
The process for getting boards designed and made is underway. Hoping to have something ready to be made by middle of April.


Thanks!

Paul
 
I had some prototype boards made and they work and fit great. The production ones I'm going to order will have either a blue or white masking. I'm going to get enough made to do all the busses in my desk but didn't know if anyone else would be interested in having some as well. As mentioned they can work as a standalone circuit or integrate in any other project that uses the proper +/- rails. The eq curves seem to match identical to a CAPI 553F (I don't have a "real" 553 and I am using the same inductors on the CAPI site). Board measures 3"x4". I could probably do $15 each shipped anywhere lower 48 states. I would have to get a rate for international friends.

I've posted the EQ curve info on my TAC rebuild thread:

https://groupdiy.com/index.php?topic=68714.msg916026#msg916026

I'll probably put in an order later next week. If anyone wants in let me know.

Thanks!

Paul
 

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