DIY Front End 2022

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The steel trafo covers are made by Antek and (like William mentioned) use a plastic shoulder washer and acorn nut, no shorted turn. For the money these covers are pretty nice.

Eric, I did notice Q5 can get warm to the touch so I put the heatsink on, probably just my OCD and not necessary.

Gary, Thanks for the helpful feedback, I started to search the thread for builder impressions with your Toshiba combo. I guess further down the rabbit hole I will go....
 

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Very nice Vunce.

Why the heatsink on Q5 ? I’ve never monitored its temperature, should I ?

I put heatsinks on my mosfets too but I have to admit that they are overkill and not necessary according to the numbers.

By the numbers, Tj max=175 C, Rthja=62C/W. If ambient=30C, then Pmax= (175-30)/62=2.3W

If current draw is 50mA total (conservative), maximum voltage drop across mosfet=2.3W/.050A= 46V. If we want to apply a safety factor, say 2, then 23V. Unless the transformer was vastly oversized for voltage, the voltage drop will be nowhere near 23V so no heatsink necessary. However that can be verified by measuring the voltage drop across the mosfet, and the current can also be determined by measuring the voltage drop across the preamp R9 or R10, so an accurate power dissipation may be calculated.

Edit: corrected a whoopsie re: current demand
 
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Hi

FE 2023 was done for Balanced Inputs, Dual Rail PSU with indications it is very flexible and inputs / PSU could be changed.
Pictures examples of Balanced XLR inputs with Dual Rail PSU: Baard #691
Pictures and/or Schematics of Unbalanced RCA inputs with Single Ended PSU +24V 6L6 #321 & #454

I would like to do Balanced Inputs XLR with Single Ended PSU +36V. I couldn't find examples and i would like to check with one of you the proper connection
In particular, should i add a connection between Input "VG" and PSU "0V" /"-"?
(dotted line on the picture, with question mark)

Thanks in advance
 

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I finally finished my FE 2022 after starting and stopping for over a year. Compared to my Whammy and Noir HP amps used as a preamp, the FE 2022 adds a lot more oomph in good ways. Pictures attached.

I fit this into a Hammond 1455T2201 enclosure. Powered by a 48V wall wart. I used a buck converter to avoid frying the 12V LED on the power switch. The cool thing about it is that I can easily set the brightness with it, too.
 

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Aavid makes a heatsink for the TO-92, and DigiKey + Mouser sell it. Check the parts list for the Noir Headphone Amplifier in the diyAudio Store -- it calls for one of those heatsinks per channel.

Some people report good results using a plastic zip-tie, to attach a TO-92 transistor to a US $0.25 coin ("quarter"), by drilling two holes for the zip-tie and using a bunch of Thermalkote heatsink grease. This merde-rig has the advantage of low cost and zero shipping fees, but the disadvantage of not having a measured, tested, guaranteed thermal resistance Theta-JA to aid design and reliability calculations. There's quite a bit of copper inside a quarter (although the exterior surface is zinc), and copper is a great heat conductor. Certainly I'm not going to publicly recommend sanding/filing/diamond honing down the surface roughness of legal tender coins -- but smoother might perhaps be equivalent to better.

https://www.aliexpress.com/item/1005005213975053.html
 

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I guess that must be an April Fools joke in #1,428, to copy the text of an older post and paste it without reference or attribution.

Aavid makes a heatsink for the TO-92, and DigiKey + Mouser sell it. Check the parts list for the Noir Headphone Amplifier in the diyAudio Store -- it calls for one of those heatsinks per channel.

Some people report good results using a plastic zip-tie, to attach a TO-92 transistor to a US $0.25 coin ("quarter"), by drilling two holes for the zip-tie and using a bunch of Thermalkote heatsink grease. This merde-rig has the advantage of low cost and zero shipping fees, but the disadvantage of not having a measured, tested, guaranteed thermal resistance Theta-JA to aid design and reliability calculations. There's quite a bit of copper inside a quarter (although the exterior surface is zinc), and copper is a great heat conductor. Certainly I'm not going to publicly recommend sanding/filing/diamond honing down the surface roughness of legal tender coins -- but smoother might perhaps be equivalent to better.
 
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Bonjour messieurs,
Si on place un potentiomètre en (avant), quelle valeur ? J'ai un journal TKD de 20 K ohms, est-ce correct ?
Quelle est l'impédance de sortie du Front-end ?
Merci d'avance.

:cop:

English please. Rules.

Hello gentlemen,
If we place a potentiometer in (front), what is the value? I have a 20K ohm TKD log, is that correct?
What is the output impedance of the Front-end?
Thanks in advance.