I'm finishing up a diy, line-level, 6sn7, preamp. I built it in a cake pan chassis using a GlassWare A3 attenuator. (Kind of a hybrid ladder/series). I need to decide on a final attenuator configuration before i can order the front and rear panels for the finished chassis. (The GlassWare actually sounds pretty good; but it is large, cumbersome, and just isn't good enough to make it to the finals.)
- I'm using Mundorf coupling caps, Takman resistors, ELMA selector switch, Vampire RCA's, teflon silver coated wiring, and Sylvania tubes. (Possible upgrade for the tubes down the line.) As it sits, without attenuator(s) and chassis/faceplates, I'm into the project about $1200. My budget was $1500, but allowing $300 for chassis and, say $150-$300 for attenuation, I'll be a bit over, but not too much. I'm very pleased with the sound and don't regret any expenditure so far.
- The basic alternatives are: 1) A single stereo control with channel balancing. Or, 2) Two mono controls. For the most part, comparable stereo attenuators cost about twice as much as two mono units. So channel balancing would be an added cost; and the balancing units need to be be the same quality as the main unit. All this points me toward dual monos. I'm skeptical about potentiometers - I feel that they're generally not up to quality of the project. So mono-stepped seems to be where my thinking is. If somebody thinks I'm over-reaching on that, then please let me know, otherwise my questions are going to focus on series vs shunt vs ladder; and brands that best meet my needs.
- Conventional wisdom is that series attenuators, because they employ lots of resistors in the path, are the weakest alternative. Shunts minimize the number of resistors, but do not use matching resistors and, therefore present impedance issues. Ladders are the best in theory, because they present only two, matching resistors for any attenuation level.
- I don't know whether all of this falls into the "Audio-fool" category or not. Certainly, I'd kick myself in the head if I short-changed the project trying to save $100; but, on the other hand, there's no reason to spend money if you can't hear it.
Also, there are details like: how many steps (12, 24, 48, 64)? what about brands, DIY or factory made (I don't mind letting somebody else sharing the soldering fun.)
Anyway, thoughts and experiences would be greatly appreciated.
- I'm using Mundorf coupling caps, Takman resistors, ELMA selector switch, Vampire RCA's, teflon silver coated wiring, and Sylvania tubes. (Possible upgrade for the tubes down the line.) As it sits, without attenuator(s) and chassis/faceplates, I'm into the project about $1200. My budget was $1500, but allowing $300 for chassis and, say $150-$300 for attenuation, I'll be a bit over, but not too much. I'm very pleased with the sound and don't regret any expenditure so far.
- The basic alternatives are: 1) A single stereo control with channel balancing. Or, 2) Two mono controls. For the most part, comparable stereo attenuators cost about twice as much as two mono units. So channel balancing would be an added cost; and the balancing units need to be be the same quality as the main unit. All this points me toward dual monos. I'm skeptical about potentiometers - I feel that they're generally not up to quality of the project. So mono-stepped seems to be where my thinking is. If somebody thinks I'm over-reaching on that, then please let me know, otherwise my questions are going to focus on series vs shunt vs ladder; and brands that best meet my needs.
- Conventional wisdom is that series attenuators, because they employ lots of resistors in the path, are the weakest alternative. Shunts minimize the number of resistors, but do not use matching resistors and, therefore present impedance issues. Ladders are the best in theory, because they present only two, matching resistors for any attenuation level.
- I don't know whether all of this falls into the "Audio-fool" category or not. Certainly, I'd kick myself in the head if I short-changed the project trying to save $100; but, on the other hand, there's no reason to spend money if you can't hear it.
Also, there are details like: how many steps (12, 24, 48, 64)? what about brands, DIY or factory made (I don't mind letting somebody else sharing the soldering fun.)
Anyway, thoughts and experiences would be greatly appreciated.
series attenuators use resistors soldered in series and use ONE tapping point (possibly multiple contact points) to pass the signal.
Ladders uses multi paralleled TWO resistors soldered into circuit and use TWO tapping points to pass the signal.
Relays use multiple resistors soldered in and multiple tapping points
One should weigh up the relative merits of multiple soldered joints versus multiple tapping/contacts.
I would prefer multiple soldered joints rather than multiple tappings. The worst being relays where the signal could pass across 8 relay contacts to get to the output.
Ladders uses multi paralleled TWO resistors soldered into circuit and use TWO tapping points to pass the signal.
Relays use multiple resistors soldered in and multiple tapping points
One should weigh up the relative merits of multiple soldered joints versus multiple tapping/contacts.
I would prefer multiple soldered joints rather than multiple tappings. The worst being relays where the signal could pass across 8 relay contacts to get to the output.
I bought some stuff from Michael Percy and have his catalog. The Shellco attenuators are just too big to work in my unit. I'm considering ELMA and Goldpoint.
In looking around, I'm beginning to think that I'm probably obsessing over the series/shunt/ladder issue. Goldpoint dropped shunt and ladder ten or fifteen years ago and now only sells series (factory assembled or diy). Frankly, the more I read and agonize, the more I'm moving toward using two, mono, Goldpoint, 24 or 47 step series models.
A dozen years ago I got one of the last shunt boards that Goldpoint had, and I still have them. I've since made a couple mono series attenuators with new Goldpoint boards. With mono attenuators you can sort of use them as a balance control but the steps are a bit large at thr usual 2db. step, but 47 step switches allow for smaller steps.
I've made a series attenuator from a Percy kit and frankly I think the Goldpoint boards are a lot easier to work with.
I now prefer LDR's, but that's another story....................
This was suggested in the Pass forums as a step above 'other' forms of Attenuation.
intact audio
May even be true. Try it?
intact audio
May even be true. Try it?
Just pulled the trigger on two, mono, 47 step, Goldpoint, factory-built, attenuators.
Don't want to think about the subject any more.
Thanks for the help, guys.
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