Using GP attenuators (2 decks) to make a 600OHM T attenuator.

[tomerttb]

Hi All, I am building Drip’s 175B Compressor project.
I have a problem that I can’t find a solution for, how to make my GP attenuators to act as 600OHM T attenuators.

I don’t know what resistors to use on the GP, and I don’t know how to connect it to the PCB.

The PCB is mark with Ground, 1, 2, 3. (Output/Input XLR)

My GP attenuator:
http://www.goldpt.com/dims.html (I have 2 decks)

The 600OHM T Attenuators
http://www.studioelectronics.biz/sunshop/index.php?l=product_detail&p=1151

I will need an easy explanation for this as I am not very experienced

Thank you very much for your help
Tomer.
???

 

[DaveP]

Hi Tomer,

No-one seems to have answered you yet, but I have used the simple attenuator on the 2nd schematic on my BA-6A page with success before.

http://www.groupdiy.com/index.php?topic=44312.0

You should notice that all the resistors add up to ~600 ohms so its a balanced divider.

The exact 600 ohms is not critical but use matched resistors if possible.

best

DaveP

 

[tomerttb]

Hi Dave
Thank you very much
Tomer.

 

[Tubemooley]

The GP attenuators are "regular" attenuators. I would need to go look at which attenuator topology (circuit) the GP's actually use. There are several. The 600-ohm T-pad attenuator is similar but different (duh). The "T" part means it is a Bridged-Tee circuit. There are T pads, H pads and maybe a couple more. The 600-ohm T-pad attenuator is used by many people in many places. It's a fairly specific thing but it can be used and works great in many circuits. But........ here's the but....... Tt's made with a triple pot and it's usually a custom pot. Go to Jeff Steiger's ClassicAPI website and take a look. http://classicapi.com/catalog/product_info.php?cPath=48&products_id=106 Two of the pots are 500 ohms and the third one is 1kohm. Jeff has a nice little wiring diagram (photo) showing how to wire his attenuator for use. His is just like everyone else's. Do a search on attenuators and look for T and H types. Alright.... So here's my point..... I'm not sure how easy it will be to actually construct a 600-ohm T-pad attenuator with the GP's. You would need a 3-deck and build two of the decks into 500-ohm "pots" and the third into a 1k "pot" and then wire them up like the 3-pot style attenuators. I'm sure it can be done but it's going to take some figuring and some work. Just like everything else. Good luck. Dana Walcott.

 

[shabtek]

t-pad is made from 3 resistors: series, shunt, series. a t-attenuator would be a series of these pads offering progressively more padding.
look up a calculator, 2 pole switch can work I believe if you tie all the low ends of the shunt arm together and switch the in and out signal to put different pads in circuit. I don't know if a 2 deck goldpoint switch would be ideal for building this on