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Attenuator talk - Page 3

post #31 of 123
12/4/08 at 9:15pm
Thread Starter 
Well, the good news is that there are still 5 of them... too bad they are $400 for the bunch... well, IF he ships to the US, as my Italian is a little rusty. Still tempted to get a couple.
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post #32 of 123
12/4/08 at 9:17pm
Quote:
Originally Posted by n_maher View Post
you're still limited to using a mechanical switch and the affordable versions of those are generally limited to 24 positions.
I'm using relays.

there there is something like this, dual mono:



or this 2-deck, 24 position switch for $20



I paid around $30 for a 4-deck version of the same switch. Ari has posted a lot of great links in other threads for decent switch vendors.

I still prefer the flexibility of relays though..
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post #33 of 123
12/4/08 at 10:08pm
Gosh darn, $75+ship for an RK40? I had no idea these got so expensive. Do those of you who have tried both feel that they are of similar quality to the CP2511? I was planning on using one of my 50k RK40 for volume control on my 300B project, and maybe another for a 'stat amp.
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post #34 of 123
12/5/08 at 12:31am
Thread Starter 
Well, the TKD cp2511 just don't sound as good to me as the cheap smd Taiwan attenuators (when they are well behaved). Could be any number of things, but I just won't use them again. While the sale at PcX helped, I might rather take a shot on the rk40 for almost the same money. Oh, they still kick the snot out of the rk27, but anymore, that isn't saying much.

To date, nothing has bested the Goldpoints, including a DACT CT-2(?), and not sure why I have wasted so much time and money not just sticking with them, as, in the end, it has not saved me anything.
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post #35 of 123
12/5/08 at 12:37am
For those who've tried it, how do you feel about the noble ap25? They're only a little more expensive than the RK27's, but I haven't seen much of it around here.
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post #36 of 123
12/5/08 at 1:05am
My experience is the same as dsavitsk, 23 steps is more than enough if the gain is set properly. Most headphones, and even speakers, need pretty similar voltage gain. Actually for the majority of headphones you don't need voltage amplification at all.

If 23 steps really isn't enough, you could always add a pre-attenuation switch (AKA "gain" switch) like I did for a Beta22 I built for amb's gallery.
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post #37 of 123
12/5/08 at 1:07am
Quote:
Originally Posted by cotdt View Post
my experience is the same as dsavitsk, 23 steps is more than enough if the gain is set properly. Most headphones, and even speakers, need about the same voltage gain.
did you read his post? you're saying the exact opposite of what he was arguing...
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post #38 of 123
12/5/08 at 1:12am
Quote:
Originally Posted by luvdunhill View Post
did you read his post? you're saying the exact opposite of what he was arguing...
I just reread his post and not sure what you mean. We're both saying that 23 steps is enough. He argues for basically using 1dB steps in the region where you typically listen to headphones, which has its drawbacks. I'm saying that you can instead just set a low gain on your headphone amp, or use a pre-attenuation switch. I mean, who listens to headphones that need +-20V voltage swing anyway?
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post #39 of 123
12/5/08 at 1:19am
Quote:
Originally Posted by dsavitsk View Post
My current amp, for instance, uses an attenuator with 12 steps. I only have 6 of them wired up, and in fact have only ever used 3.
-d
I thought his point was 24 steps is way more than anyone would need.
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post #40 of 123
12/5/08 at 1:24am
I was considering getting an attenuator from that other site, pabbi, which I see you are also getting some from. I held off because I recalled how dissatisfied I have been with these big volume increments. I was hoping you would say the TKD CP2511 were almost as good, though if the RK40 is, I will be happy, as I still have the three I bought from the JBL tent sale a few years ago. I mainly use Nobel AP25 pots in my builds, but that is more because I picked up a sack of them surplus for $2 each, so didnt see the point in buying RK27 pots.

Quote:
Originally Posted by cotdt View Post
I mean, who listens to headphones that need +-20V voltage swing anyway?
Besides people with 'stats, 'trets, or piezos? Ortho heads take a pretty good amount of drive.
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post #41 of 123
12/5/08 at 1:47am
Thread Starter 
To be fair, they seem to be settling down a bit (I do believe in burnin), but these sounded better. I was also hoping the TKD would be the end of the road, except I am itching to try the TKD 2P65S, as an end of the road for me, knowing I am NOT going rk50.

I am going with the DACT as a known quantity, for $100 less than the equivalent Goldpoint, but was going Goldpoint or with the TKD IFF the design warrants it - hopefully it will. In fact, the TKD were purchased for the new thing, but the crap attenuators in the Bijou forced my hand.
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post #42 of 123
12/5/08 at 2:10am
How about Penny & Giles rotary faders? Those are infinitely adjustable right? Shallco also makes some good attenuators, up to something like 45 steps, IIRC.
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post #43 of 123
12/5/08 at 2:24am
Quote:
Originally Posted by cetoole View Post
Besides people with 'stats, 'trets, or piezos? Ortho heads take a pretty good amount of drive.
The electrostatics/piezo's do need more than 20v swing, but I think its safe to assume that since they will need a dedicated amp they can be considered separately. They still get by with less then 60dB of range.

orthodynamics dont take much more voltage than "cone and coil" dynamics. You may wind up shooting yourself in the foot with output impedances... but we are just talking about voltage swing even if you consider the effects of highish output impedance on a low-impedance headphone you will probably still find you dont need 60db of control range to cover most dynamic (non-K1000) headphones.

1v (RMS) will make virtually any dynamic headphone play at stupid volume levels (including orthodynamics). The fact that the amp can swing 20v is barging rights and overhead. Is it worth adding more active parts to get a few dB of extra voltage headroom? I certainly agree there is a point below which your "headroom" is Inadequate, but once you pass that point... When you view active parts as distortion generators as well as voltage/current manipulators more is not necessarily better.

The fact that the amp has unity gain (or is an attenuator) does not detract from its ability to pass large signals. There are buffers designed to pass at least 20v. The nelson-pass/first watt F4 comes to mind.
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post #44 of 123
12/7/08 at 1:46am
pabbi1,
i think you ought to try a ground-shunt - 2 deck for unbalanced, and 4 deck for balanced. i can send you the BOM from Mouser and schematic i used for my attenuators in my Bijou. 23 positions is more than enough for both my HD650 and K701 with 1 dB steps over the critical range.

i have a good line on some D9 Electroswitches at 1/2 price, but they're a bit "industrial" in turn-over force. definately not "consumer grade".
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post #45 of 123
12/7/08 at 2:29am
why not a straight shunt with 2 decks?

2*100K plus a 10-K-ohm attenuator should skim offf extra gain plenty well.
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