Finished up my stock Iron Pre this afternoon. Sounds really nice so far! Was a breeze to build and setup. I only ever use a single source at a time, and bypassed the relay's and twister for now. As stated in a previous post, I'm using a regular old pot for attenuation to start with, and then hope to swap in the Slegle $200 autoformer pair for attenuation soon. Shooting for an Iron Pumpkin Lite, if you will
Thanks to ItsAllInMyHead for the free prototype board! I used his BOM for anything I didn't have, and it worked perfectly. I say these are definitely ready for the store.
Last but not least, thanks to ZM for the superb design, layout, and constant help. You're the best!!
Thanks to ItsAllInMyHead for the free prototype board! I used his BOM for anything I didn't have, and it worked perfectly. I say these are definitely ready for the store.
Last but not least, thanks to ZM for the superb design, layout, and constant help. You're the best!!
Attachments
That doesn’t sound normal… .....
agree
and , taking in account simplicity of both concept and construction, I can't even think of any scenario what Cody ooked there?
as far as I remember Iron Pre was already made with all 3 types of xformers - Edcor, Jensen, Cinemag
I may need to double-check resistor values? I kinda feel like it may be an output impedance issue. I was also looking back to see if the Jensen required any clipping, bridging, etc
*Edit* Since I recovered these Jensen's from my F6 boards, also considering the fact that perhaps I boogered up a winding..
*Edit* Since I recovered these Jensen's from my F6 boards, also considering the fact that perhaps I boogered up a winding..
Last edited:
Hey Jim!
Nothing is hooked up to CT thru holes. The transformer has two 18V secondaries, wired in series to get my 36V. Voltages in the reg are rock solid at +/- 15V. 1263 is the final wiring. Also included a better board shot here. Signal ground is coming from RCA in (confirmed isolated from chassis) to the input. PCB is grounded at a single star point in chassis (via onboard NTC). I confirmed continuity to chassis.
Confirmed correct resistor values in the buffer section.
Out of curiosity, I hooked a powered sub I have. Take a parallel set of RCAs from the pre out to the sub. Normally there’s no detectable change in sound, but this time I noticed what sounded like even more roll-off. The sub had a pretty high input impedance, so not sure how/why it had that impact, but perhaps greater minds will prevail.
Nothing is hooked up to CT thru holes. The transformer has two 18V secondaries, wired in series to get my 36V. Voltages in the reg are rock solid at +/- 15V. 1263 is the final wiring. Also included a better board shot here. Signal ground is coming from RCA in (confirmed isolated from chassis) to the input. PCB is grounded at a single star point in chassis (via onboard NTC). I confirmed continuity to chassis.
Confirmed correct resistor values in the buffer section.
Out of curiosity, I hooked a powered sub I have. Take a parallel set of RCAs from the pre out to the sub. Normally there’s no detectable change in sound, but this time I noticed what sounded like even more roll-off. The sub had a pretty high input impedance, so not sure how/why it had that impact, but perhaps greater minds will prevail.
Attachments
Last edited:
Hey, problem solved! 6L6 noticed that I'd tied my two secondaries in series at the transformer, as opposed to running those legs to the CT spot for the series connection. I just made the switch and I've now got full range and full power. Thanks Jim!
you're lucky that we have Hawk Eye Jim around ( thing of Trade, I believe)
I can bet that guiding wannabee Pilots is easier than coping with regular Greedy Boyz
I'm really glad that you didn't ( at least that we know of) made so substantial omission, while making monoblocks
say - same situation as going out on jogging, with laces on your joggies ........ unlaced
Yeah, it’s fair to say I didn’t take the same level of care with this project.
- Home
- Amplifiers
- Pass Labs
- What's wrong with the kiss, boy?