Iron Pumpkin(s) and other smaller vegetable animals

Official Court Jester
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Hi zenmod! Looks great. And those $200 AVC's look interesting too!

With regards to the diamond buffer, what is the benefit of the current mirror over a CCS of some kind? And how did you tune it to a similar distortion structure as the jfet complementary buffer?

if you look again at buffer schematics , BD transistors are doing all work , while small JFet (MMBF5486) is working as 5mA CCS , which is , again , biasing current mirrors up and down on rails

so , there it is , you have CCS :clown:

THD spectra is result of currents and voltages involved

besides - that Diamond buffer is hardly anything new under the sun
 
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ZM - thank you, but I should have phrased that better. Why that particular type of CCS? I see it's quite elegant to use the one jfet for two (matched!) Ccs's... Actually, I guess that's the why. :D :dunce:

Thank you - cheers for the explanation. :)
 
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Official Court Jester
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I did write that ..... AVCs are on Hitachi Metglas cores , my own custom ones

winder is not exactly Beautiful nor Virgin ....... but he is a friend :clown:

maybe I'll open Trade thread later tonight , but all technical info is ( I think) already there

regarding Cinemags and Jensens ........ we can mention them only in context of Iron Pre , which is pretty similar but certainly enough different beast - distinctions already written about more than once

Jensens deliberately chosen for Iron Pre pcbs , by 6L6 ..... I'm not doubting his choice and reasons

I believe you will get them and JFets , as part of Store package
 
Official Court Jester
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yup

there are wirepads on board for regular pot (right after selector) ; cut trace between pads, include pot ;

wire any other autoformer instead of AVC

that speaking of Iron Pumpkin

speaking of Iron Pre - 6L6 is having first pcbs ; I can always edit gerbers to accommodate pinout for other autoformer
 
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Official Court Jester
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Hi Zen-Mod,

Impressive work. No wonder it took a while.

I'm thinking about the Iron Turtle SE AVCs and whether they can be used for multi-channel preamp applications. In particular, for my case, for digital crossovers.

I don't need the capability now, but if investing in the Iron Turtle AVCs, it would be nice if they would work in that application in the future.

So can the SE AVCs be ganged via the flat cable or is that capability just used on the balanced AVCS?

Or could there be a special rotary switch with multiple flat cable outputs?

The Iron Turtle ability to tweak output gain per channel would be another plus for multi-channel applications.
 
Official Court Jester
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yup

you can daisy chain control of Iron Turtle ......... at least 20 of Turtles controlled with one rotary switch :clown:

edit - that's why I put place for two 50pin pcb connectors on Turtle pcb

so , besides having flat cable going through connector to second (etc.) connector (sorta as IDE cable having Master and Slave connectors) , there is also possibility of second cable

so , dress/organize them as most convenient
 
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Zen Bro, Regarding your statement:

"Disclaimer – as for difference to almost all AVCs on market , these aren't intended to be Swiss Knife universal jobbies , they are constructed to be driven with buffer or , at least , pretty potent signal source apparatus."


How potent? (thinking of output impedance of DACs and also tube buffers)
 
Official Court Jester
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say that anything above 50R of Rout is anyway wimpy , at least by my standards

I did wrote in Iron Pre thread , speaking about Iron Pumpkin development , that Iron Turtle is easily driven with Toshiba JFet complementary buffer

that's it ......

regarding tube buffers - I like tubes , and exactly because of that ,I know that there are no many tube buffers around , being both capable ( cojones) and linear ( not compressing one side of signal ......

for small signal , you can hardly beat Toshiba JFet buffer