mike stehr Posted December 14, 2003 Share Posted December 14, 2003 I bought a stepped attenuator off Ebay, some Vishey/Dale 23 stepped stereo thing. I have a bunch or BB opamps and a little breadboard, I wanted to make a little active volume control. I finally got both sides working, didn't sound too bad either. I was using my NAD amp to test it out. Except the left side when you switch the steps up and down, it pops and clicks. (Not really a good thing, considering it shouldn't break contact before contact is made.) However, coupling some moderate sized caps on the outputs of the attenuator killed the popping. (I just coupled both sides to keep it even.) By the time I kinda dialed it in, I guess ended up wiping out one of the opamps, and lost one side. So I just ran line level with 100 ohm resistors in the inputs of the attenuator and out with the coupling caps to the amp, passive. Not bad, not bad at all. beats those cheap carbon pots. I'll try this with a tube amp later, in the passive setup. I still want to try it with the active configuration, it may be nice for some extra gain. I have few more BB 2134's to kill. What's really nice is I can switch sources, my Carver is about dead. I scored a nice little wood dovetailed box with honeyroasted peanuts, from a Christmas party. I'll mount everything in the box. This will get me by until I figure out a tube linestage. Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted December 14, 2003 Share Posted December 14, 2003 Talk about being resourceful! Great idea and good job with those snubbers on that killed the popping. With sensitive speakers, those can sound like cannon blasts! Hey, Mike? You know we'd all like to see this little line amp you built -- I know I would. Can you take a picture? I've been known to take the highest quality digital photographs in the central U.S., and my knowledge of digital photographic computer applications is now legendary. Let me know if I can help. (please know that all that was 100% B.S.) I actually think I saw the very attenuators you are talking about -- 100K ohm units, with little diagrams showing the locations of input, output, and ground? I almost bid myself! Erik Quote Link to comment Share on other sites More sharing options...
jt1stcav Posted December 14, 2003 Share Posted December 14, 2003 ---------------- On 12/14/2003 5:56:17 AM mike stehr wrote: ..."This will get me by until I figure out a tube linestage". ---------------- Don't know what kind of system you've got and what you're looking for spec-wise, but this BEZ Model Q4B 6SN7 SRPP linestage pre (with a 23 step volume control with 1/4W(1%) resistors) from Edmund Lam of Hong Kong is a steal at only $255 on eBay (do a user ID search for "zagger1"). I love mine (and will love it even more once I do some NOS tube rolling), and can't wait for the companion 8 WPC BEZ Model T3B 300B SE tube amp to arrive! Quote Link to comment Share on other sites More sharing options...
Marvel Posted December 14, 2003 Share Posted December 14, 2003 Back in the early '70s, while working at a TV station, the assistant engineer gave me two Daven stepped attenuators off of an old console. Still have them, with the cool knobs. These are 600 ohm input and output, balanced. Smooth as can be. Daven is out of business, but you can still find them on ebay once in awhile. I have even thought of selling the ones I have. Marvel Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 14, 2003 Author Share Posted December 14, 2003 If your hurtin' for cash, the Daven's do well on Ebay. I'm aware of the Bez linestage Jim, and it's a helluva deal. But I wanna build one. It may end up costing more, but I like the learning experience. I'm preparing the little wood box for the attenuator, caps and input jacks. I tried it with Rega Planet and the SE 6BQ5 Magnavox amp just as a passive line level, it seems to have plenty of gain with no pops or clicks. Though I do want to try the active line stage option, I'll reprep the breadboard for another try Tomorrow. I like this attenuator. I'll post a pic when I get everything put together, Eric. It's a easy project. Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted December 14, 2003 Share Posted December 14, 2003 Some of the problems with the attenuators is that too many appear too coarse a setting between detents. I find it necessary to have ones that offer a pretty refined adjustment although with some sensitive gear, it's still a problem. My current TKD stepped attenuator has 41 steps. This really plays a role when your amp in VERY sensitive and your output from the line level source high. As for phono, this is almost never a problem given that most are always looking for gain. I have seen those units on ebay as well. I find my TKD made a big difference from even a well regarded NOBLE pot I had before it. It was substantially more expensive than the 23 step unit you got. So if that gain is ok and the transparency there, you got a great deal. kh Quote Link to comment Share on other sites More sharing options...
sheltie dave Posted December 14, 2003 Share Posted December 14, 2003 Mike, I was digging through the boxes I've collected buying the various items, and I noticed I have a remote controlled Creek volume attenuator, an OBH-10 with power adaptor and remote. I'm going to try it out tomorrow and run the Nak cd into the Dynaco amp. If it works well, you are welcome to it until you get your preamp all built I actually got the shorthorn I bid on(unsuccessfully) down in New Orleans. Mike threw it on Ebay the second time, almost back-to-back, and had a BIN below what I tried to offer him during the first auction. Good show to get some decent attenuators, now you can really give the Rega a workout! We got two inches yesterday, so we're running around in St. Louis with our toques on as well. Happy holidays! Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 15, 2003 Author Share Posted December 15, 2003 ---------------- On 12/14/2003 11:42:03 PM sheltie dave wrote: Mike, I was digging through the boxes I've collected buying the various items, and I noticed I have a remote controlled Creek volume attenuator, an OBH-10 with power adaptor and remote. I'm going to try it out tomorrow and run the Nak cd into the Dynaco amp. If it works well, you are welcome to it until you get your preamp all built. ......................................................... Sure! If you really want to loan me your 250,300 dollar passive linestage. The thing is, who knows when I'll build a tube linestage. Hell, the world could end before then! Try it out, I know it will have a transparent feel about it. Nothing like your Cary overall sonically, but might be interesting to compare. The first thing I noticed when I tried my attenuator, was the transparency. It kinda reminds you of no volume pot. It makes you wonder what the transformer attenuators are like. Send me that Creek, we can work something out, or if you want to wait for awhile until I cobble up a linestage. It's up to you. It keeps snowing and melting. Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted December 15, 2003 Share Posted December 15, 2003 I think there is a little confusion here in that the Creek OBH does not include a stepped attenuator. It's a regular volume pot... The Creek IS a passive device though and with a remote as well. So what Dave was referring to was a passive device with one set of inputs that can be controlled with remote (it's the same as the OBH-12 but with one input). I wish the OBH did have a stepped attenuator, though. Dave, ole Mike's attenuator he just bought has a resistor for each volume setting verses a variable resistor volume pot. That is actually what is usually meant by stepped attenuator. Besides that info, the little Creek is a neat little device and does eliminate the active line stage which can be mediocre on poorly designed preamps. kh ps- OF note, this version is a "SHUNT" type http://www.progressive-engineering.com/klipsch/stepped_shunt.jpg Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 15, 2003 Author Share Posted December 15, 2003 Yeah, that's it. I take it the Creek uses a Alps or Noble pot. Quote Link to comment Share on other sites More sharing options...
3dzapper Posted December 26, 2003 Share Posted December 26, 2003 ttt Quote Link to comment Share on other sites More sharing options...
sheltie dave Posted December 26, 2003 Share Posted December 26, 2003 Kelly, Mike, etal, what is the difference betwee a passive vs regular preamp? I know the gain normally is advertised arond twenty dB vs 30 dB or so for an active, so I'm assuming there is a transformer or other item that will boost the voltage signal the final decade? Now that I have the ultracool Passive Creek(aka too lazy to get off my but), it would help the cachet value to actually know something Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted December 26, 2003 Share Posted December 26, 2003 I'm neither of the guys you asked for this info, but the difference between passive and active is just that -- one does not do anything more than control the volume of the source -- which is where the power comes from. In a passive preamp, there is no extra gain or boost in gain as there is with an active linestage. It's basically just a volume control and switch (for different sources) installed in a box. If you interconnects are not more than a few feet, they can be really good. Quote Link to comment Share on other sites More sharing options...
sheltie dave Posted December 26, 2003 Share Posted December 26, 2003 Erik, thanks for the info. I thought that to be the case, but I wasn't sure. You are one of the knowledgeable people on the forum - hence my "et al" in the header It's great being able to get good answers from multiple folks! Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted December 27, 2003 Share Posted December 27, 2003 Mike, here's the text from my reply to you over in the other thread: ------------------------------------------------------------------------- Mike, I got a reply from him. He mentions availability of mono units and a smaller diameter version after the first of the year. I thanked him and mentioned the issues raised in your thread, sent him a URL for it, invited him to stop by. see what happens. his emails are short, he's either pushed for time, has language barriers or both. I'm thinking the nice resistors are really a separate issue from the pot in the center. if the pot has problems with the moving contact/wiper, the quality resistors won't help. Tom Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 27, 2003 Author Share Posted December 27, 2003 Thanks Tom. Quote Link to comment Share on other sites More sharing options...
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