What's wrong with the kiss, boy?

[Baobei]

I measure 8.2V across ZD2 (which seems correct looking at the schematics). ZD1 seems odd though, measuring around 1.5V first and steadily dropping to around 3mV. Maybe I got the wrong diode or fried it somehow?

EDIT: That's the one I got

 

[Zen Mod]

if there is any mistake, blame me ........ or even better - blame Pa

this will help

edit: ignore ZD1-ZD2 designation

as I wrote somewhere, due to mishap with my PC years ago, I unfortunatelly lost consistency between sch and brd Eagle files for this project, so had to wrestle with that even until now, evidently

red written numbers are how zeners needs to be placed

 

[Baobei]

That makes sense, thanks. I guess previous builders actually knew what the parts are supposed to be doing and were not just following the schematics

 

[Zen Mod]

I've told you , blame Pa

that's what I'm doing, whenever my responsibility becomes an issue

keep us informed what you did

 

[Baobei]

I swapped the diodes and I measure ca. 22V across + and -. The relays seem to work. Still no music unfortunately, but I think the problem is with the volume control... so need to figure that out.

 

[codyt]

When using an AVC with the Iron Pre, would the AVC ideally replace the existing onboard iron? I'm sure this is written somewhere, I just haven't found it.

 

[Zen Mod]

yes, just short pot pads and that's it

 

[codyt]

And if I'm using just one input, I can skip the relay's, their PS parts (M3, ZD1, ZD2, R25, C13), and input directly at wiper and ccw?

 

[Zen Mod]

sorry, point me to schematic of your reference

 

[codyt]

I was just following traces on the PCB I have, but looking at the schematics makes it a bit more straightforward. I don't see an issue, but you may

 

[Zen Mod]

yup, no relays, no need for parts situated in upper right corner

and yes, input ditto at wiper and gnd beneath

then to AVC of your choice and World is your Oyster

I'm spoiled - once when you properly try inductive attenuator, there is no back to resistive one, doesn't matter how it's made

 

[codyt]

I'm excited to give it a try!

 

[flocchini]

With your Singing Bush it will be Audio Nirvana

 

[ItsAllInMyHead]

Cody, I can't wait to hear what you think. I have my SE Iron Pre staring at me longingly. The balanced is in my system. I may try to outfit the SE with an AVC and give it a try before going with the full Pumpkin. You've inspired me.

 

[Zen Mod]

Boyz, you can't tell that I didn't gave you (that) simplest recipe - myriad of times

 

[ItsAllInMyHead]

Yes, ZM, you are correct. I have the recipe. I have to order one key ingredient (the AVC), and quit drinking the cooking sherry.

Cody just inspired me to get my apron out and show that a home cook and replicate the recipe from the master chef.

 

[Zen Mod]

 

[flocchini]

I went back and read the first twenty or so posts of

Iron Pumpkin(s) and other smaller vegetable animals
Iron Pumpkin(s) and other smaller vegetable animals

the Gain Structure piece and the PSM LS Cookbook

What a wealth of information and what a Pre

My favorite description by Aleksandar

"well - foot-tapping , music is there ..... no thoughts about spectrum dividing , music is simply there"

 

[Russellc]

Following up with the 2016 board, stereo.

I changed my speakers from Pioneer SP-FS-51LR to Polk lsi15. This increased the hum. I cut the ground trace and this resolved the issue.

Still sounds sweet, with babelfish 2j as the amplifier.

Thanks again ZM !

I also built the 2016 boards, and had a similar hum. I forget now without going back in this thread to where I built mine, but later to clear up some other minor deal. I went ahead and also cut those other traces around the relays that ZenMod suggested. Total quiet, no popping between channels, etc. Really love the PS and relay board (I usually use a teabag Inselect here) all on one board.

Hopefully this will be available in the store soon. I believe it is likely my best preamp at this time. It really depends on the mix of other components. The 2018 WLS is very nice. I'm going to build another, board done, and combine it with one of those Muse volume controls. Will make a fine pre I'm sure.

No love lost for the BA3 either, I use two of those! Glad your Iron Pre worked out, you will get much pleasure from that one.

Russellc

 

[Russellc]

Cody, I can't wait to hear what you think. I have my SE Iron Pre staring at me longingly. The balanced is in my system. I may try to outfit the SE with an AVC and give it a try before going with the full Pumpkin. You've inspired me.

I will be watching this one for sure. Will have to wait for another board to be available, (maybe I'll get inspired enough to do this one) hate to not have this pre as is. On other hand, I'm headed to build a SE version of Iron Turtle at some point...

Which AVC are you going to use? The $200.00 dollar one discussed in the other thread, or ZenMods?

Russellc