Mini-Me phono preamp

Some nice info here :).
First (about capacitors on bottom side), I did not expect that these tubes emit that much heat that would harm capacitors, but photo from Jazid tells me otherwise (and a thing to consider when designing a case). Regarding other capacitors, thanks for the tip about Solens, I may give them a try, firstly I have to check my stash :).
Alos, BOM is allways handy - perfect.

As for transformer, I haven't really considered ebay sellers (30 USD for piece is really nice), but I can always send and email. I might as well check locally for options.
Thanks!
 
From boydk,

Quote:
Originally Posted by Boydk View Post
I got mine made a little smaller. Wrote an E-bay seller if he could get them made, and yes, 5-7 workdays, so guess he´ll be shipping them about now.
PRIM 0-115, 0-115
SEC 0-120v 40mA
0-120v 40mA
0-6,3v 1,2A
0-6,3v 1,2A

I ordered 5 pcs. and got them for 25$ a piece.

https://www.ebay.com/str/along1986090

My source:2N1357 voedingstrafo voor buizenversterkers 48VA

I need some clarification..
According to schematic output is 2 x 12V, 100mA, and you ordered 40mA, that is OK?
And other secondary is 2 x 6.3V, and per schematic is 1 x 12V, so just curious, why the complication?

Sorry about quoting, something may be wrong on my side.
Thanks
 
Jazid got it :)
I wanted to keep it as small as possible and versatile for future builds (120v x 2 or 240v x 1, 6,3v or 12,6v).
6N16B is an astonishing sounding tube for audio, but doesn´t need more than a couple of mA´s per section = 40mA is more than enough. 2 X 6,3v = 12,6v.
12v or 12,6v....... potato.... potaaaato :)
 

PRR

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...Heaters seem to only consume 760mA for all four, spec suggests 400mA? They look just fine and run at 200mA if at 12.6V. ...

If they were perfect resistors, rated 400mA at 12.6V, and you run at 12.0V, then we expect 762mA. 762=760 for any practical purpose.

(Red-hot filaments are NOT "perfect resistors", their resistance rises with temperature, but for a 5% difference of V the R won't vary much.)

And in nearly any case, oxide-coated cathodes in low-level audio, rated 12.6V, work just as well as 12.0V. There is a wide tolerance before they get "under-heated". "potaaaato" indeed.
 
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Alternative for powertransformer see schematic below.

Use two transformers.
One 36va with 230 or 115v primairy according to your net, with 2 x 12v/1,5a secundairy.
And one 12va with 2 X 115v primairy / 1x 9v.

Connect as in schematic and you have 1 x 12v/1.5a, and 2 x 125/130v/25ma output AC for the mini-me.

Cost will be about €25,-.
 

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Playing music at last, and insulating sleeves fitted for safety. It's still in its 1st hour and lovely wide and deep soundstage, still settling in of course. I'll let it settle down for say 50 hours to see how I feel and then move it to a case. Any suggestions on something available in Europe that looks nice - have to be 45mm clear height inside minimum, and advice on how close the trafo should be while avoiding hum? What have people used succesfully here?




An externally hosted image should be here but it was not working when we last tested it.
 
This one.... with 8mm black, blank plexiglass/acrylic front looks really gorgeous, and the price doesn´t scare anyone :)

DIY AUDIO Chassis Toroidy DT5 - Shop Toroidy.pl

I used these in full size (width) for my X-Ono phonostage and PSU. Looks really good (at least I think so) :)
My DIY DAC at the bottom, PSU and X-ONO and on top is my DIY Silk Audio SUT.

Maybe you should just use 2 enclosures, 1 for riaa and 1 for PSU :)
 

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Playing music at last, and insulating sleeves fitted for safety. It's still in its 1st hour and lovely wide and deep soundstage, still settling in of course. I'll let it settle down for say 50 hours to see how I feel and then move it to a case. Any suggestions on something available in Europe that looks nice - have to be 45mm clear height inside minimum, and advice on how close the trafo should be while avoiding hum? What have people used succesfully here?

An externally hosted image should be here but it was not working when we last tested it.

To avoid contact humm place transformer in seperate housing.
 
Know, this was for Koifarm, just my input....
Depends on, what you mean by "similar material". Alu isn´t very good for screening transformers. That´s why I chose Toroydi´s cases. They´re made of steel, and do a much better screening. Guess you could get away with transformer in same enclosure, if you use a full width enclosure, mount the transformer as far away form the Mini-Me and encapsulate it in some kind of steel screening case, but it´s just a guess.... haven´t tried :)
 
Thanks BoydK the toroidy cases look right for my needs.
Koifarm, how does putting the trafo in a separate box stop the hum that a shield of similar material wouldn't? Not challenging, just interested to know...

The tubes are microphonic and everything what is vibrating(50/60hz transformer) without mechanical decoupling to the tubes will insert humm thrue the tubes in to the audio signal. Best decoupling is to use separate housing for powersupply(housing) So this is no magnetic or electrical induced humm but mechanical induced humm.
 
Good point Koifarm.... although our experiences might vary on the subject :)
My own DIY dac in 2modul/43 cm enclosure uses one 6N16B-V pr. channel in SRPP mode as final gain stage. It suffers from 3 toroids in the enclosure, and it´s absolutely free from any hum or other bad influences.
But of course I agree with your point.... Different enclosures are the optimal solution :)