What's wrong with the kiss, boy?

[stoolpigeon]

in general, with repeater coils (old name for 600:600 jobbies) it's irrelevant which one you use as secondary and which one as primary

further - if you see one side having more Rdc, that's secondary

if all windings are having same Rdc, irrelevant

Thanks again Zen Mod, my friend has measured them and it looks like all windings are the same and around 50 ohms or a bit less dc (he just has a primitive analog meter for car repairs).

sp

 

[Zen Mod]

good

when you get it, if you have problems with pinout, just buzz for help

all you need is DVM and laptop/PC soundcard output - they're made for headphone load, so useful for noncritical test

and yes, either simple prog for sine generator or file of 400Hz-1Khz

 

[peppennino]

Ha!

Got a Letter from 'Talian Cousin .......

View attachment 1102852

 

[Abx74]

Hi everybody

Is there anything wrong using autoformer for 6 ou 12dB gain with a salas DCB1 ?

Damien

 

[schultzsch]

Hello Damien,

6db is 2x voltage gain or 2x turns ratio, 12db is 4x voltage gain or 4x turns ratio.

The impedance ratio(your question if it works or not is related to this) is equal to its turns ratio squared this meaning that:
-for 6db your output impedance will be 2x2 x input impedance, so output impedance will be 4x input impedance
-for 12db your output impedance will be 4x4 x input impedance, so output impedance will be 16x input impedance

The dcb1 output impedance is ~120r.

With 6db trafo you will have ~480r output impedance and with a 12db trafo you will have ~1920r.
480r is ok but 2k is a bit high.

What is the input impedance of the next stage you wanna drive with the dcb1+autoformer ?

 

[Abx74]

Thanks for this answer.

Next stage could be VFet P-channel, BA3, Pass AB100...depend of the mood...

 

[schultzsch]

@Abx74 if you have some spare time I do suggest reading this article https://www.psaudio.com/pauls-posts/output-impedance/

Now you know the output impedance you will get with with your 6db or 12db preamp and you also know the input impedance of those amps you mentioned above.
Read the article in the link and then check if your preamp-amp combo satisfies the condition mentioned in the article.

 

[Ylab]

Question for mighty ZM, for trim pots P3 and P4, better to go with 20R or 25R if I can not find any 22R?

Thank you!

Hubert

 

[Zen Mod]

good praxis, always doubt in Mighty ZM's musings

22R isn't exactly standard value for pots, even if it is for resistors

so, just another Brainfart of MZM, nothing unusual, I did learn from The Best One

(don't tell anyone, but I did catch Pa melting 5 channel amp, according to Iq settings in Service Manual)

yup, 20R

 

[Ylab]

I’m having a hard time finding a relay that is equivalent. The Fujitsu RY-24W-K is out of stock.. I’ve found this Panasonic AGN20024 that seem compatible. But I’m not sure, so many parameters.

Edit: oups, didn’t saw they don’t have the same footprint. Back to research

​

 

[Zen Mod]

use RY-12W-K

need to change just one zener in circuit - 27V is for 24, 16V is for 12V relays

as I see, drekload of these, link above

 

[Ylab]

Great thank you ZM

 

[Abx74]

Mighty Zen,
I run dual mono with my amp, is there any advantage to choose dual mono with a preamp ?

Damien

 

[Zen Mod]

always

in case of Iron Pre SE, there are cap multipliers for each channel rails

in case of Iron Pre Bal, fully dual mono, if there is dedicated mains xformer for each channel ...... or dedicated secondaries in case of using one mains xformer, common for bot channels

 

[Abx74]

And what do you think about separated PSU ?
xformer/rectifier bridge/first cap in a box and another cap near the circuit in a second box...

 

[chromenuts]

Picture’s worth a thousand words…

https://www.zenmod.in.rs/iron-pumpkin-another-one/

 

[Zen Mod]

And what do you think about separated PSU ?
xformer/rectifier bridge/first cap in a box and another cap near the circuit in a second box...

I'm always following Monkey which is most successful in rattling my Cage

Feel free to do the same



(last time I checked Iron Pre , I had all rectification and filtering on board)

 

[Zen Mod]

Picture’s worth a thousand words…

https://www.zenmod.in.rs/iron-pumpkin-another-one/

this is thread about Iron Pre, not that one

 

[chromenuts]

Yeah…just figured you building fancy smancy Iron Pumpkin with tranny in same case was a “goose and gander” example

Didn’t mean to create confusion 😁

 

[Zen Mod]

yeah, but then, I'm using custom Donuts - having both Static and Magnetic shield

not wound for low flux, just normal proper

smaller Donut 10VA used for relays (and logic/TFT if used)
bigger Donut 20VA used for audio circuit, each channel having separate secondary, so practically dual mono