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Awesome build, Dan! My work schedule has been heinous for the past month, so I’m just now catching up on your adventures. Using silver wire this way is a bit of work to get things cut to proper length. It’s not the easiest, but I still have plenty of silver left over, so that’s what I used. I’m thinking Zen’s iron pumpkin is my last preamp build, it’s a real beauty!
Bummer about your tree! I had a big one come down in a storm a few summers ago, interrupted my speaker build, very inconsiderate!!
Bummer about your tree! I had a big one come down in a storm a few summers ago, interrupted my speaker build, very inconsiderate!!
quite logical last one you needed to build, but certainly not last one you want to build
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Ha, gotta agree there! A few more builds and I’ll need a bigger house!
I gotta follow up here.....
I've been living with the Iron Pumpkin in my main "system" since November when it knocked down a +100ft tall Douglas Fir in my backyard. The Pumpkin still amazes me with both its power and finess, and all living creatures within earshot are obsessed with the sound. This is the best preamp I've ever owned. I've run this into F5m, Aleph Jzm, XA252, F4, ACA Mini, and Pass Labs x350.5 and they all sound amazing. I want to build another it sounds so good.
I'm so happy to be an Iron Pumpkin owner!!!!
Thank you Zen Mod!
I've been living with the Iron Pumpkin in my main "system" since November when it knocked down a +100ft tall Douglas Fir in my backyard. The Pumpkin still amazes me with both its power and finess, and all living creatures within earshot are obsessed with the sound. This is the best preamp I've ever owned. I've run this into F5m, Aleph Jzm, XA252, F4, ACA Mini, and Pass Labs x350.5 and they all sound amazing. I want to build another it sounds so good.
I'm so happy to be an Iron Pumpkin owner!!!!
Thank you Zen Mod!
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seconding ( probably been said many many times before ) I have "no" desire to try anything else [ no in "" because the elusive turtle still plagues my dreams ]
I have never been at peace with my system but oddly enough, I am now.
..dB
Hi Patrick, I’d be interested to hear your thoughts on how much of a step up in SQ the Pumpkin offers over the Iron Pre ?
Unless I’m missing something (highly likely!), this would seem to have quite profound gain structure implications. With a normal resistive volume controller it would seem mad to add gain that you don’t need and to then throw it away again by turning the volume down. In contrast with the AVC, adding gain but turning the volume down would seem to have no penalty and may even be better. Am I right?
technically, everything is clear - Rout falling with square of voltage ratio, where initial being Rout of buffer itself; from top of my head that's no more than 30-35R (just starting first morning coffee, so even dumber than later in the day)
sound-wise - for my ears, no comparison between resistive attenuator and inductive
disclaimer - making simple resistive is darn simple and usually cheap - thinking of "passive pre"
complications arose when going from there, in any direction
Iron Pre nice specimen of "activated passive" with nice band-aid, in form of autoformer on output ......... as silly-free-lunch ingredient
at least for majority of Greedy Boyz, who did tried
sound-wise - for my ears, no comparison between resistive attenuator and inductive
disclaimer - making simple resistive is darn simple and usually cheap - thinking of "passive pre"
complications arose when going from there, in any direction
Iron Pre nice specimen of "activated passive" with nice band-aid, in form of autoformer on output ......... as silly-free-lunch ingredient
at least for majority of Greedy Boyz, who did tried
Hiya!
All caveats apply per usual re: not being able to offer terribly meaningful impressions, but ... I have a few thoughts. Mostly it depends on the Iron Pre and the attenuation you choose.
For me / after a good bit of time having the Pumpkin Balanced as the primary pre in my system and not swapping it out for anything else since I built it, except to briefly test a few things, I can say with confidence that it is the best pre-amp I've ever had for listening at what I commonly call "don't wake wifey" levels.
Here's the rub though.... I think (I don't know) that specific attribute is largely due to the Turtle.
To me... I never heard a big difference (if at all) when I swapped out Alps pots for fancy (still resistive) pots in my original Iron Pre SE or Balanced.
I thought I heard a noticeable difference when swapping from the original Iron Pre to the new Iron Pre SMD. I think when I was testing it, I sent his mightiness a note with the words "snappy" and "fast" and "articulate" or something like that. He sent back an emoji, per normal. The new SMD Iron Pre is a bit closer to the Iron Pumpkin in it's character, which makes sense.
When I build the Iron Pre SMD Balanced with the Muses controls from Frank, I thought it was an improvement, particularly at lower levels (higher attenuation) even though technically, it's still resistive attenuation. I could have lived with that pre-amp forever, but I really, really wanted to try the Pumpkin.
When I swapped in the Pumpkin, at 'normal' listening levels / dance party levels, if you blindfolded me... I truly doubt I could tell the difference between Pumpkin and Iron Pre Balanced with Frank's Muses.
tl;dr - My gut tells me that an Iron Pre with a Slagle (or other) AVC may be dangerously close to a Pumpkin. Only his Mightiness or others that have compared the two would really know for certain.
as long listening room isn't overloaded, there is a substantial (enough) and justified difference; most easily described as greater sense of easiness of sound
above that, In Vino Veritas
Close, but no Cigar
that for SE
speaking of Bal, taking in account that I really couldn't find (anywhere else) proper balanced AVC, go figure
^ It's just that good.... 
Plus, I could never think of a clever back panel for my Iron Pre builds. I love my Great Pumpkin....
Plus, I could never think of a clever back panel for my Iron Pre builds. I love my Great Pumpkin....
Wow IAIMH
I’ve only been hoarding what you’ve already built and tried.
I snagged a pair of Slagle autoformers that came up cheap in the swap meet recently for an Iron Pre build that I want to put together to replace my trusty old DCB1 that I “KISSed” with Jensen iron several years ago. It would be for my secondary system.
Maybe I should just send the Slagles to you for comparison testing!
The Iron Pumpkin is coming along slowly…sometimes just a few parts at a time. It’s not easy to be hunched over the bench for a long period of time.
I didn’t realize how long it’s been since I ordered the original Pumpkin boards. Must have been before BAF 2019.
I was looking for some reference pics for my board version and had to dig through the beginning of the thread to find something the same.
Oh well, if I had built it right away I wouldn’t have the opportunity to have all the bells and whistles and the sexy case 😉
Had some fun playing origami with pot legs yesterday to try and get them to fit the footprint of the boards without interfering with resistors nearby.
I’ve only been hoarding what you’ve already built and tried.
I snagged a pair of Slagle autoformers that came up cheap in the swap meet recently for an Iron Pre build that I want to put together to replace my trusty old DCB1 that I “KISSed” with Jensen iron several years ago. It would be for my secondary system.
Maybe I should just send the Slagles to you for comparison testing!
The Iron Pumpkin is coming along slowly…sometimes just a few parts at a time. It’s not easy to be hunched over the bench for a long period of time.
I didn’t realize how long it’s been since I ordered the original Pumpkin boards. Must have been before BAF 2019.
I was looking for some reference pics for my board version and had to dig through the beginning of the thread to find something the same.
Oh well, if I had built it right away I wouldn’t have the opportunity to have all the bells and whistles and the sexy case 😉
Had some fun playing origami with pot legs yesterday to try and get them to fit the footprint of the boards without interfering with resistors nearby.
^ Awesome!!!!
The Iron Pre is just that good... it blew me away. Then, there were a 'few' iterations over time as we got it into the store.
I know that I've built at least 14 full Iron Pre projects. That's separate from a few boards that went to friends for 'testing' etc. or just swapping out pots or other simple changes (like swapping out Jensen / Cinemag / Edcor)
Oh, my 'project wait list' (the pile of boards and parts) is embarrassing.
The Iron Pre is just that good... it blew me away. Then, there were a 'few' iterations over time as we got it into the store.
I know that I've built at least 14 full Iron Pre projects. That's separate from a few boards that went to friends for 'testing' etc. or just swapping out pots or other simple changes (like swapping out Jensen / Cinemag / Edcor)
That is very, very kind, but please hang onto them. All of my Iron Pre builds found their way to other members.
Recently decided to see if there was anything to the "never stack components" maxim. Been meaning to for some time, but the system sounded so good, it was easy to put off.
I am still trying to comprehend how as little a change as can be seen in the before and after pics can yield such dramatic results.
Nothing new was introduced except the hardware store furniture sliders in place of the casters, just rearranged the components using the vibration dampening pads (from Herbie's in Austin, TX) that were already in use.
SQ improvement put a big grin on my face that is still there every time I listen. I'm talking across the board better, particularly female vocals.
I even think I know now what "micro dynamics" can do for sound reproduction .
I've said before that the "music was all there", well now maybe that is actually so.
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