600 ohm T attenuators?
- Thread starter kdawg
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martthie_08
Well-known member
Inspired by NYDave's posts, I have this on the output of my v72's and it works pretty swell:
http://www.groupdiy.com/index.php?topic=106619
cheers, Marten
http://www.groupdiy.com/index.php?topic=106619
cheers, Marten
NYD - You ARE the man!!! :sam: :guinness: :sam: :thumb:
mikeyB
Well-known member
What 3 decks would be required to make 600R attenuator - small quantities could be made by Omeg here in UK - let me know details and i'll submit a quote
davoux
Active member
Ed Anderson has a boat load of these he is nearly giving away. He calls them T-pads. Its a 3 layer Pot 600 ohm each. He says it is same as Purple MC-77. If you look in the black Market for him, you will see posts for either edanderson or edanders.
Cheers, John
Cheers, John
NewYorkDave
Well-known member
In a T-pad, the shunt arm has to be more than 600 ohms at zero attenuation. Think about it. The two series arms are 0-600 ohms, though, so you're two-thirds correct.
The data is there to figure this all out with only a small investment of effort. I know I'm starting to sound like Grouchy Gus
razz, but I've also noticed that many are not willing to take the initiative and are just looking for a paint-by-numbers answer. You don't learn much that way.
A resistive attenuator in a circuit with known impedances is a fairly straightforward thing and it's a great way to cut your teeth in applying basic arithmetic to circuits.
Some people just wanna build a clone and don't give a damn about learning anything about electronics. That's valid, too, but I choose not to humor those people since nobody's paying me a dime to post here, and I'd rather focus on helping someone who wants to learn something about the art--as opposed to a project studio owner who's just looking to save a few dollars by building an SSL clone.
One last piece of advice: if you're getting custom pots made, might as well go with a bridged-T since it only requires two sections (and two external resistors). If running calculations for several steps of attenuation makes you cross-eyed, here's a web-based calculator which I've found to give good results:
http://www.microwaves101.com/encyclopedia/calcattenuator.cfm
Enter "600" in "Zo" and just plug in the attenuation values; 2dB steps should give you enough resolution to plot the resistances on an Excel graph, which you can then give to your pot manufacturer when specifying the tapers you need. The calculator doesn't accept an input of zero for attenuation, so you can start at a fraction of a dB to give you an idea of the total resistance of the shunt arm. (For instance, 0.1dB gives a result of 52K for shunt and 7 ohms for series).
OK, that's all I'm gonna say about it... I mean it this time.
The data is there to figure this all out with only a small investment of effort. I know I'm starting to sound like Grouchy Gus
razz, but I've also noticed that many are not willing to take the initiative and are just looking for a paint-by-numbers answer. You don't learn much that way. A resistive attenuator in a circuit with known impedances is a fairly straightforward thing and it's a great way to cut your teeth in applying basic arithmetic to circuits.
Some people just wanna build a clone and don't give a damn about learning anything about electronics. That's valid, too, but I choose not to humor those people since nobody's paying me a dime to post here, and I'd rather focus on helping someone who wants to learn something about the art--as opposed to a project studio owner who's just looking to save a few dollars by building an SSL clone.
One last piece of advice: if you're getting custom pots made, might as well go with a bridged-T since it only requires two sections (and two external resistors). If running calculations for several steps of attenuation makes you cross-eyed, here's a web-based calculator which I've found to give good results:
http://www.microwaves101.com/encyclopedia/calcattenuator.cfm
Enter "600" in "Zo" and just plug in the attenuation values; 2dB steps should give you enough resolution to plot the resistances on an Excel graph, which you can then give to your pot manufacturer when specifying the tapers you need. The calculator doesn't accept an input of zero for attenuation, so you can start at a fraction of a dB to give you an idea of the total resistance of the shunt arm. (For instance, 0.1dB gives a result of 52K for shunt and 7 ohms for series).
OK, that's all I'm gonna say about it... I mean it this time.
edanderson
Well-known member
[quote author="davoux"]Ed Anderson has a boat load of these he is nearly giving away. He calls them T-pads. Its a 3 layer Pot 600 ohm each. He says it is same as Purple MC-77. If you look in the black Market for him, you will see posts for either edanderson or edanders.
Cheers, John[/quote]
that is not accurate. i had 4 "tpads" that were made by omeg for me a few years ago.
THEY ARE ALL SOLD NOW, I DON'T HAVE ANY MORE.
i'm not interested in getting any more. but here is the info, in case someone else is: they were non-bridging type, with two linear 470ohm decks and a log 1kohm deck. all three wipers connected with a piece of buss wire. this is electrically similar to the attenuator used in the purple mc77, but much lower quality. personally, i think the omeg parts felt like crap, and the plastic shaft feels cheap. then again, they WERE cheap, well under $10 each at the time.
if someone else wants to order some, go for it. they are inexpensive and are close to what you want for the input of an 1176. NOT the same as the bridged type t-pad, still available from PEC. i'm not providing any more info; i'm in the same camp as NY dave -- you guys can figure this out without my help if you put minimal effort into it. i'm trying to help you guys in other ways and this would just be a distraction.
please do not PM me about this.
ed
Cheers, John[/quote]
that is not accurate. i had 4 "tpads" that were made by omeg for me a few years ago.
THEY ARE ALL SOLD NOW, I DON'T HAVE ANY MORE.
i'm not interested in getting any more. but here is the info, in case someone else is: they were non-bridging type, with two linear 470ohm decks and a log 1kohm deck. all three wipers connected with a piece of buss wire. this is electrically similar to the attenuator used in the purple mc77, but much lower quality. personally, i think the omeg parts felt like crap, and the plastic shaft feels cheap. then again, they WERE cheap, well under $10 each at the time.
if someone else wants to order some, go for it. they are inexpensive and are close to what you want for the input of an 1176. NOT the same as the bridged type t-pad, still available from PEC. i'm not providing any more info; i'm in the same camp as NY dave -- you guys can figure this out without my help if you put minimal effort into it. i'm trying to help you guys in other ways and this would just be a distraction.
please do not PM me about this.
ed
KeithFisher
New member
- Joined
- May 11, 2008
- Messages
- 1
If any parties are interested in a group buy for the Clarostat 70 series 500L ,1KA, 500L three decks let me know. If we can get to the 25 part price you're looking at about $36. I would hope that people would buy 2 to get to the quantity faster and make things a little easier on me with the shipping.
Don't PM me use email below
:grin:
Don't PM me use email below
:grin:
Siegfried Meier
Well-known member
I have a Mallory 600 ohm T-pad that I bought last year. I can't seem to find any wiring diagrams for connecting it to an 1176 Rev D. Should have wired it up when things were still fresh in my mind, but alas. I've been reading a lot of stuff for the last 3 hours, but still can't find what I'm looking for. The search in the new forum seems to not be up to snuff quite yet...
Any help much appreciated!
Thanks,
Sig
Any help much appreciated!
Thanks,
Sig
Denyle Guitars
Well-known member
Siegfried Meier said:
Take a look at Purple Audio's MC77 manual/schematic and it'll become clear.
http://www.purpleaudio.com/pdflib/PurpleMC77v34.pdf
Siegfried Meier
Well-known member
I've read it, but I'm just not getting how this all comes together on the actual unit. Perhaps if I made a picture diagram it would help. Please let me know if this is correct...
Also, do I need to put resistors on this thing?
Thanks!
Sig
Also, do I need to put resistors on this thing?
Thanks!
Sig
edanderson
Well-known member
that is right. no resistors needed.
ed
ed
Siegfried Meier
Well-known member
Awesome thanks guys!!
SIg
SIg
Echo North
Well-known member
Just an update on this older post for those searching...
I sell 600 ohm t-pads at Hairball Audio:
http://hairballaudio.com/shop/product_info.php?cPath=21&products_id=33
And they are also sold at classicapi.com:
http://classicapi.com/catalog/index.php?cPath=48
You can't go wrong at either of these places
Thanks,
Mike
I sell 600 ohm t-pads at Hairball Audio:
http://hairballaudio.com/shop/product_info.php?cPath=21&products_id=33
And they are also sold at classicapi.com:
http://classicapi.com/catalog/index.php?cPath=48
You can't go wrong at either of these places
Thanks,
Mike
bushwick
Well-known member
Question for those of you who've continued with this quest. I am looking for a couple of quality 600Ω or 1kΩ Bridged Tpad pots for the output of a Fairchildy compressor. Looking for audio taper and in this case something with a 1-1.5" shaft. Can anyone point me to some help?
Thanks much,
Joshua
Thanks much,
Joshua
