I fully admit that I get a certain grin on my face when I look at a new schematic and know that I have a part in my stash that will work. Party on!
Just a follow up to IAIMH's most recent post regarding additional items for the iron pre. The Alps RK27 10k link is for a dual pot, so suitable for the SE version, I assume. So one dual pot required for SE. Can anybody confirm?
I found 2 other Alps RK27 single pots on mouser with part numbers RK271111001T and RK2711120026. The RK2711120026 is detented with 31 positions while the RK271111001T has no detents. I'm assuming these are the pots needed for the balanced version and 2 single pots are required? Again, can anyone confirm?
*EDIT. I just noticed the single pots are 100k Ohms, so are these suitable at all? I guess there's always the option of using 2 dual 10k pots and just use them as singles? *
BTW, I'm basing this on the Modushop's SE and Balanced chassis that are available for the Iron Pre. (aside: what's the plural form of chassis? It's chassis. I had to look that one up).
Big thanks to IAIMH! And of course huge thanks to some user named Zen Mod 🙂
I found 2 other Alps RK27 single pots on mouser with part numbers RK271111001T and RK2711120026. The RK2711120026 is detented with 31 positions while the RK271111001T has no detents. I'm assuming these are the pots needed for the balanced version and 2 single pots are required? Again, can anyone confirm?
*EDIT. I just noticed the single pots are 100k Ohms, so are these suitable at all? I guess there's always the option of using 2 dual 10k pots and just use them as singles? *
BTW, I'm basing this on the Modushop's SE and Balanced chassis that are available for the Iron Pre. (aside: what's the plural form of chassis? It's chassis. I had to look that one up).
Big thanks to IAIMH! And of course huge thanks to some user named Zen Mod 🙂
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I was in the same situation for my last build of this preamp and I was happy to have most of the extra parts like you mentioned. I am no expert but I don't think that a capacitor will degrade substantially for a few years after manufacture. As to reforming them, it would seem that would likely apply mostly to high voltage caps, right fellas?
Hi @anoob -
The link to the pot should be to a dual gang pot. One gang for each channel left and right => one of those pieces for an SE unit.
For a balanced version you need four gangs (+L, -L, +R, -R signals). So, you'd either need a quad gang pot (they are available) or 2x dual gain pots like the ones linked. The Modoshop Iron Pre Balanced chassis has holes pre-drilled for two pots in the front panel.
Sorry for using the word dual to mean two separate things, I can see how that may cause confusion.
I hope that makes a little more sense.
The link to the pot should be to a dual gang pot. One gang for each channel left and right => one of those pieces for an SE unit.
For a balanced version you need four gangs (+L, -L, +R, -R signals). So, you'd either need a quad gang pot (they are available) or 2x dual gain pots like the ones linked. The Modoshop Iron Pre Balanced chassis has holes pre-drilled for two pots in the front panel.
Sorry for using the word dual to mean two separate things, I can see how that may cause confusion.
I hope that makes a little more sense.
SE requires one dual pot.
Balanced requires two dual, or one quad-gang pot.
Balanced requires two dual, or one quad-gang pot.
Sort of a semantics type of thing except these are two different preamps using the same circuit design, but one is double of the other. This may be one of the reasons that I stay away from balanced designs. Unless you have a need by way of source or amp in your system, you might as well stick to using only half of the circuitry required for SE use. I had an almost completely balanced system once. Man was there ever a lot going on.
Found post #3690 on page 185 about halfway down. Just great looking work. I am starting to wire my present project am still glad now that it isn't balanced. That is a lot of wiring, but fortunately the Iron Pre negates the need for as much wiring with the relays.
@edwinjones4 with the balanced boards orientated as you show, the best place for the pot IS the front.
There is a reasonable argument that extensions are better for the SE board, particularly when mounted longitudinally, but I put the potentiometer on the front of SE and it's quiet and sounds great.
There is a reasonable argument that extensions are better for the SE board, particularly when mounted longitudinally, but I put the potentiometer on the front of SE and it's quiet and sounds great.
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I've linked an Alps RK27 Remote Mount 3D print design that can be used with the Iron Pre SE. Currently in draft as of today, and I'll update the thread with the latest revisions once it's been tested out in the wild. As 6L6 noted, probably not needed for Iron Pre Balanced if mounting boards as he did, but for the SE version, it can be used reduce wire length if the board is oriented front to back in the chassis.
https://www.diyaudio.com/community/...t-remote-extension-mount.418116/#post-7801500
https://www.diyaudio.com/community/...t-remote-extension-mount.418116/#post-7801500
Can we get a Balanced Chassis face plate with a Single volume control hole (rather than two as show below). And further, can the single volume control
hole be center aligned to the label text above it - so that it basically has the same visual appearance as the SE Chassis? I think this would be a tiny CAD file change. Are others interesting? I intend to use a single rotary encoder that will feed either MUSES or ladder attenuator.
What sort of output drive capability does this Iron Pre have? I have all balanced, transformer input tube amps. My Lynn Olson Amity Clone's are tough to drive because the reflected miller capacitance of the driver tubes grids appear at the input transformer. I think it's equiv to 600pF. LOL!
hole be center aligned to the label text above it - so that it basically has the same visual appearance as the SE Chassis? I think this would be a tiny CAD file change. Are others interesting? I intend to use a single rotary encoder that will feed either MUSES or ladder attenuator.
What sort of output drive capability does this Iron Pre have? I have all balanced, transformer input tube amps. My Lynn Olson Amity Clone's are tough to drive because the reflected miller capacitance of the driver tubes grids appear at the input transformer. I think it's equiv to 600pF. LOL!
say that smd iteratioon of balanced Iron Pre is having Rout under 300R
do your math ..........
though, 600pF is most likely wrong number
Attachments
I've been working on this project for a while... I finally finished it.
Here's my take on the Iron Pre Amp with AVC (Iron Pumpkin Jr.?). I love the way this pre-amp sounds. Actually it's the way it doesn't sound, it's so transparent. Thanks again to ZM and ItsAllInMyHead et al for getting these to the store.
Cinco
Here's my take on the Iron Pre Amp with AVC (Iron Pumpkin Jr.?). I love the way this pre-amp sounds. Actually it's the way it doesn't sound, it's so transparent. Thanks again to ZM and ItsAllInMyHead et al for getting these to the store.
Cinco
I ordered myself a balanced kit. I have this pair of really nice vintage Daven/Shallcross 24 position make before break switches. Torn between choosing to build the pots or buy just buy a COTS and get going instead of building. What are folks preferences?
In case I go the build route, any one hve resistor values for 10k (i am assuming that is optimal) pot?
Regards, Vinay
In case I go the build route, any one hve resistor values for 10k (i am assuming that is optimal) pot?
Regards, Vinay
I am still trying to wrap my head around this beautiful piece of work. So... this is what a TVC would turn out to look like. I just didn't have that much of a picture in my mind's eye. I really like the chassis as well. Good and heavy duty.
