I'm a bit over my skis. I purchased a stereo balanced stepped attenuator for my balanced iron pre, and I'm not sure how to wire it. I took a picture and labeled the connection points between the boards and the attenuator. Do these connection points look correct? The ground, in and out labels correspond to the labels provided by the manufacturer.
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Sorry for those that saw the previous post before I deleted it. I had a brain fade... you need BALANCED.
Common is "GND"
Output is the terminal on the pot that goes lower in resistance relative to GND when you turn the pot in the way you want the volume to decrease.
Input is the input signal.
So if your pot is labeled correctly - the simplest way (for me) without going through each set of 3 connections is...
If you have your pot labeled properly.
CCW on board goes to EARTH on POT
Wiper on board goes to Out on POT
CW on board goes to In on POT
That's true for all four sets of three. You currently have them mixed between the positive and inverted signals. (In post 3781)
As always... someone should double / triple check my work.
Edited for simulpost - Second diagram above looks correct, and I added a note, so others can follow.
Common is "GND"
Output is the terminal on the pot that goes lower in resistance relative to GND when you turn the pot in the way you want the volume to decrease.
Input is the input signal.
So if your pot is labeled correctly - the simplest way (for me) without going through each set of 3 connections is...
If you have your pot labeled properly.
CCW on board goes to EARTH on POT
Wiper on board goes to Out on POT
CW on board goes to In on POT
That's true for all four sets of three. You currently have them mixed between the positive and inverted signals. (In post 3781)
As always... someone should double / triple check my work.
Edited for simulpost - Second diagram above looks correct, and I added a note, so others can follow.
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Thanks so much. I'm surprised I don't see more balanced pots/attenuators in completed builds, as most are using dual. Am I missing something (probably)? I would go crazy constantly trying to get the volumes equalized.
4 gang pots are becoming more and more rare. Also... you get your own "by ear" balance control with the dual pot method. Totally understand if that may make you nuts. It did to me at first, but then when I realized that it was AWESOME for the 95% of the time I sat way off axis... I got over it.
Any time - Truly didn't mean for it to be a "gotcha" type statement. I really do get a better experience when I sit off axis. I sit on a couch sometimes that is perpendicular to the "listening" couch. It's great. I know some people agonize (and I appreciate that they do) with things as nifty as pointing their tweeters where their left and right ears may be typically to get 'perfect' imaging. That's not me. I wander around the room a lot. Having an easy / quick way to adjust the balance without the pitfalls of some balance solutions... is pretty cool. It truly does outweigh the one negative (which is rarely all that great anyway in most pots) of having easy-peasy channel matching.
Mainly - Enjoy your build. Looks like it's going to be fantastic!
Exactly. 🙂
Oh I didn’t take it as that. I sincerely appreciate your help and agree with your comment.
I used a 4-gang EIZZ stepped attenuator for one Iron Pre Balanced build and love it. Recently I made another as a gift for a good friend, and he wanted dual pots, so I used two stereo EIZZ attenuators, since he wanted the ability to balance each channel when sitting off-axis. That is a great feature for those of us who don't have a "perfect" seating location, and I've got a few preamps with dual controls that work well for me, though I know some people don't like them.
I've built all my preamps (including the SE Iron-pre) with separate L&R volume pots for the same reason(s) as IAIMH's. I move around my room some which doesn't put me directly between my speakers when I sit down. It's a bit of a pain but you learn to appreciate the simplicity/flexibility. I've always wanted to try this route (https://www.academyaudio.com/product-page/vcu-hi-end-muses-micro-volume-control-board) but never could motivate myself to give it a try.
Cheers,
Pete
Didn't know whether this should be posted here or in the other sub-forum (What's wrong with the Kiss, boy?). My build & my playing around....I built the board according to the BOM/parts supplied in the kit. I had a 3/8 aluminum plate sitting around from something else so that was used for isolation from (possible) transformer noise. As mentioned in #3791 I used dual mono pots for better L-to-R balancing.
It was a wonderfully clean, sharp & uncolored signal between the DAC input and output to the amp. Bass response was succinct & unmuddy. It really is a preamp that gets out of the way of the signal/music. But, I preferred a bit more warmth to the sound and a tad more spaciousness. Could have been my amp's character, or my speakers or my 60+ yr old ears. My comparison preamp was Wayne's BA2018 which I preferred more than any of Papa's DIY front ends or preamps.
I won't go thru how I arrived at this ending but the Iron-pre is now as beautiful as it was before but a bit more bottom warmth to what I hear (mostly classical & jazz)... values of components are unchanged.
Vishay naked Z-foil resistors (0.1%) at R28&29
Matched DALE RN55s at R30-33 (tried 0.5W Audio Note Tantalum resistors here..just awful sounding)
Nichicon KAs at C12-15
Audio Note Kaisei polars at C16-19
Audiofool components fer sure. But many thanks to His Lord & Master Foogly ZM for a great sounding preamp. I may have to repost the picture if it comes out with lousy resolution. The pic was taken with the stock components,
Cheers
It was a wonderfully clean, sharp & uncolored signal between the DAC input and output to the amp. Bass response was succinct & unmuddy. It really is a preamp that gets out of the way of the signal/music. But, I preferred a bit more warmth to the sound and a tad more spaciousness. Could have been my amp's character, or my speakers or my 60+ yr old ears. My comparison preamp was Wayne's BA2018 which I preferred more than any of Papa's DIY front ends or preamps.
I won't go thru how I arrived at this ending but the Iron-pre is now as beautiful as it was before but a bit more bottom warmth to what I hear (mostly classical & jazz)... values of components are unchanged.
Vishay naked Z-foil resistors (0.1%) at R28&29
Matched DALE RN55s at R30-33 (tried 0.5W Audio Note Tantalum resistors here..just awful sounding)
Nichicon KAs at C12-15
Audio Note Kaisei polars at C16-19
Audiofool components fer sure. But many thanks to His Lord & Master Foogly ZM for a great sounding preamp. I may have to repost the picture if it comes out with lousy resolution. The pic was taken with the stock components,
Cheers
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that one doing lousy job, comparing to trice thinner ferrous plate, speaking of barrier to magnetic fields
you can always try some loading of output; 10K pot across output and fiddle; if you like it in some position, disconnect, measure and replace with fixed resistor
idea is loading buffer/autoformer combo to invoke some more 2nd
Your preamp, as built, is dead quiet. Nothing heard when ears close to woofer or tweeter...but, I could mount a 1/16 to 1/8 inch (1.5 - 3mm) steel plate on one side of the aluminum plate.
Without a scope it would be hard to exactly match L&R outputs harmonics with just one's ears? Papa Pass had a similar option on BA3 when used as just a preamp.
Overall, a great diy preamp.
Cheers
if quiet already, why bother
not scope but relatively simple THD Spectra measurement setup - 'puter, sound card and software; but - no rocket science - sweet spot must be found by ear and nature of the beast is that you'll don't need measuring to confirm uniformity between channels
easy to try and 50% chances that it'll do something to your liking
I purchased a rotary AC switch for this project and am struggling to wire it. It allows two transformers to be switched on in a staggered fashion. The three positions are: all transformers off, transformer 1 on and transformer 2 off, and both transformers on…I would of course always have both on. Any guidance would be greatly appreciated.
