Would love to build a serious Mic Preamp. Suggestions?

Started by iandy4, November 04, 2011, 03:39:16 AM

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iandy4

So I can't afford the n72 seventh circle kit yet but I'd like to try this hamptone design in the meantime.  I was hoping someone can give me advice on a few of the components in the schematic that are unclear to me. 

http://www.tangible-technology.com/ipr/AE230/html/wk_6/hamptone_fet_scan.pdf

As for as the transformers go, for the mic preamp design that he shows, the schematic shows one 1:1 transformer and one 1:10 transformer.  What should the ohm's be for those and which manufacturer should I go with if I quality is the top priority?  I have some quality 10k:10k transformers from edcore and those standard xicon ones as well.  Would 10k:10k be good for the 1:1 transformer? What values for the 1:10 transformer?

Also in the schematic the resistors have either "Q" or "H" after there values.  What does that mean?

One electrolytic cap also says "LO ESR" What does that mean?
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artifus

#21
QuoteAlso in the schematic the resistors have either "Q" or "H" after there values.  What does that mean?

Q = 1/4W
H = 1/2W
1% metal film

QuoteOne electrolytic cap also says "LO ESR" What does that mean?

Low ESR Capacitors: Fact or Fiction?

http://www.jensen-transformers.com/apps_sc.html

http://www.lundahl.se/schematics.html

Johan

Quote from: iandy4 on November 08, 2011, 12:48:19 PM
As for as the transformers go, for the mic preamp design that he shows, the schematic shows one 1:1 transformer and one 1:10 transformer.  What should the ohm's be for those and which manufacturer should I go with if I quality is the top priority?  I have some quality 10k:10k transformers from edcore and those standard xicon ones as well.  Would 10k:10k be good for the 1:1 transformer? What values for the 1:10 transformer?

I've had good experience with OEP A262A3E ( RS has them ) they are 1:6,3( or 1:3.15 or 1:12.6 depending on how you hook them up) and quite good at budget price( ~15euro). you can hook them up for 150 Ohm or 600 Ohm primary, so most mic's can get their optimum loading. don't forget the screening can...
J
DON'T PANIC

iandy4

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