What's wrong with the kiss, boy?

[Russellc]

Do you have a non-AJ amp to try? Random I know...and I'm no grounding expert. AJ and Iron is super nice though—My AJ isn't quiet however. And I've tried a lot of things to make it so....Noise went up a hair with Iron Pre for some reason, and Iron Pre alone was quiet. Inputs shorted—headphones on the outputs—stethoscope style (Don't fire it up with headphones on your ears!).




@Russellc and Dennis re gain settings: We preferred 6db. 12db was fine—seemed better at 6db though—something about "more clarity, less crunch", feelings mostly, but audible we felt. HOWEVER. This was with M2X... Iron + Iron. On my list is to try it with the F5. I'm feeling that could be a winner.

I've listened to it with M2 and Aleph J Quite a bit, lately have been really liking it with BA3.

Russellc

 

[Zen Mod]

A few more checks. Still on single board powered up only.

Psu is 14.98 +/-
Pin 2 is 0.0mV

I removed the jumpers / bypasses I installed for cinemags and used 12db jumpers. Still hums. Shorting an input silences that channel. Other channel still hums.

try routing your input twisted pair directly to buffer input

hot to end of R28, gnd to central GND point

 

[rhthatcher]

Still humming into R28 hot side and straight to ground.


I'm poking around the transformer traces.


Pin 1 goes to: J2&3, C3&4, E2 Appears OK
Output - J5, C11, E5 Appears OK

Pin 3 goes to: J1, C5, E1 Should it be C2 instead of C5?
Ground: J4, C2, E3 Should it be C5 instead of C2?
Does the swap of C2/C5 really matter? Is it P1:S1 / P2: S2 for Jensen and Edcor P2: S1 / P1:S2 for Cinemag? Does this matter?



I can't find a trace for the connection on the schematic from Pin 3 / J1 (Primary 1) to J8 (Secondary 2). That's the jumper added. It appears this won't work for Jensen, Edcor, or Cinemag. Is that true?

 

[rhthatcher]

Well.... upon closer inspection I think my snubber caps are swapped! I’ll let you know results after a correction.

 

[Abx74]

Hi,

is it possible to use IronPre before a BA3 (meaning BA3 Amp and FE) ?
And has someone try different transformer Jensen, Edcor, or Cinemag ?


Damien

 

[6L6]

Yes, of course!

All the transformers are good. 😀

 

[Abx74]

Ok Thanks, it is good To know that there is no bad choice 🙂

 

[Abx74]

Is there a BOM available for the IronPre ? I don't see it...


Damien

 

[Zen Mod]

Iron Pre SE files

you can make your own from enclosed files
print parts placement in proper size then use ruler to get pinout for few parts - elcos for example

all resistors are regular metal films (600mW, 0207 size)

caps - none of them needing more than 35Vdc rating

note: one pcb for stereo (two channels)

 

[Zen Mod]

Iron Pre (Bal) files

note: one pcb per channel

 

[6L6]

ItsAllInMyHead made a BOM for Iron SE.

 

[Zen Mod]

BOMs

note - Eagle generated, so compare with schmtc, triple check

schm name/values are reference

 

[ItsAllInMyHead]

ItsAllInMyHead made a BOM for Iron SE.

Yes, I am happy to share my personal BoMs for both the SE and BAL. PM if needed. With that said, I just used the same files that ZM posted to create mine. I got direct recommendations from ZM for the relays and the volume pot(s). Where I needed specific guidance was to find the proper input selector to match the physical layout of the "twister" board to ensure a proper fit (pins) and that it was the proper switching mechanism. I also did my own tweak to have my "mute" for the balanced version to have an LED. Nothing in the BoM should be too challenging to source.

An absolutely fabulous (IMO) pre-amp that hasn't left my system since I put it in. Listening to it right now. 😀 I need to give it a better chassis, but I can hardly bear to take it out in order to do the mods. Maybe in the winter.

 

[Zen Mod]

just make another one

 

[ItsAllInMyHead]

Hmmmmmmmmm.....

I don't think the current chassis is toooooo bad, but it deserves better. Posted pics earlier. Just really sloppy drilling for Neutrik XLR inputs and outputs. I also want to have my lettering CNCed into the panel vs. my label maker tape. 😀

I have boards and parts for another few builds. I want to try a Muses with Iron, but I was going to use existing boards. I could build one with Muses and leave existing. Can AVC work with this properly? I don't see why not, but there is still a dream of the proper Turtle / Pumpkin. That could lead to some interesting fun.

I need to also put my SE in a chassis. Since I switched over to the balanced, it is lonely.

 

[Zen Mod]

oh, sweet torments ......

🙂

 

[qwertyl]

Just wondering about the attached schematic - is M1 (IRF9510) connected correctly or should Drain and Source pins be swapped?

 

[Zen Mod]

source is at rail, drain to GND, applies to both M1 and M2

so, drawn properly

I can make F5 killer of it, if you wish

 

[qwertyl]

source is at rail, drain to GND, applies to both M1 and M2

so, drawn properly

I can make F5 killer of it, if you wish

Yes, M2 is Ok - source at rail, drain to GND, but M1 looks like source is to GND and drain at rail. Or is it just my tired eye? 😉

 

[Zen Mod]

blame Eagle part package if inherent diode is ooked up

I don't care (or remember orientation) for inherent diode or even an arrow - I'm always looking that gate pin is closer to source pin on symbol

🙂