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Topic: attenuator source

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Posted by Romy the Cat on 02-23-2007

Since my resent tweeter projects went through so successfully and since I would like to stay with ability to adjust the tweeters output:

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PostID=1487

I wonder who makes good L-pads. Currently I use regular Philmore L-Pads for $5each. They are low plain-vanilla, low power wirewound attenuators that maintain a fixed impedance. I have no problems with them sonically. Still, I would like to have stepped attenuators made from approved by me fixed resistors but I do not know pope who makes the L-Pads stepped attenuators. Do you know of any?

An alternative version would be to order a custom L-Pads rotary switch form Shallco or Alma for instance and put in there own resistors. However, when I looks at the microscopic values of individual precision resistors and to the opportunity of burning fingerers and soldering all of it I really would like to pay off money to somebody and do not be invalid into this project.

I remember there was Taiwanese guy who made custom attenuators with RN60 resistors and Alps switches.  They were small, accurate, very nicely soldered and very reasonably priced. I do not remember he made L-pads but perhaps for premiums pay he, or someone else would do it….. Perhaps to use 4 attenuators would be a solution to maintain impedance but I still hope to find a company of an individual who can do exactly what I looking for – 8Ohm stepped attenuator for >24 positions…. Any leads?

The Cat

Posted by drdna on 02-23-2007
Romy,

Dave Slagle at www.intactaudio.com does a lot of projects of this nature.  I am sure he would be able to make something to your specifications.

Adrian

Posted by Romy the Cat on 02-23-2007

Thanks, Adrian, as I underused the Dave Slagle is autoformer guy. I have no needs for autoformers as I need purely restive load. I fact it is not big deal to find switch,  it is complicated to find a ready to go attenuator. Mike Percy care many switches with double deck that have a poll with return path that might be used for any T-pad, N-pad, L-pad or even better a bridged-T attenuator. The problem is not with the switch but with finding the necessary set of resistors.

When you calculate the values for 8R L-pad it will be many bogus 3.65 Ohm or 6.73Ohm values. Since I would  like to go for metal film resistors it is imposable to find the necessary, even approximate values. Sure it is possible to parallel them and use many other tricks this but I do not want it. It potential to order the Vishay S102 of the very exact value but for $15 per resistor they are way out of the picture. A good solution would be to get some Nichrome, Kanthal or some other resistive wire and to make own exact values but I would prefer to find out if anyone dose it out there already as I’m sure it is a trivial task for someone. Why not to pay money to the professionals and to have the ready-to-go solution derived to you?

The Cat

Posted by NBC on 02-25-2007
Hi Romy, If you scroll down to the bottom of the page, there are 3 units supplied by Fostex:

http://www.madisound.com/cgi-bin/index.cgi?cart_id=1455929.29661&pid=315

Neil

Posted by Romy the Cat on 06-16-2007
My new 20L and 30K L-pads for the 6-chenals Super Melquiades’ tweeters and Injection channels. They are 24dB down by 1dB, made on the Elma Rotary switches and stuffed with unavoidable RB60 resistors. I did not want to burn my fingers and outsourced the project. It was built by Yen Cheng Kuo from Taipei (kyc111@hotmail.com). The piece is extremely reasonable, communication and serves are prefect. 

 The caT

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