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    the safety precautions around high voltages.

Match priorities to schematic & toobs

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rick57

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Joined 2002
#1
A talented & kindly friend :wiz: has offered to ease some of my sonic torment (aka diy torpor :ashamed: ), and design and build a preamp (for compensation of cause). :drink:

Initial thoughts are where conflict emerges, priority is given to/ not given to:

Lack of harshness 95% :cloud9:
Detail 80% :up:
Transient response 90% :checked:
Warmth 60%
845 like meaty richness 75% :worship:
Extension 50% :apathic:

You might say (without triggering other debates) the smoothness & detail of ribbons, with the dynamics of horns 😀


And design ideas:

(Because it will be driving horns and no gain is needed) 0 or 1 gain stage. 0?
Phono stage will be Hageman off-board
Lower mu tubes
Lower current Tubes
Maybe PX25/ 801/ 10/112A/ RE134/ 6072?
Or class A?

fcuk modernity, maybe built into say an old bakelite mantle radio case :cubist:


Existing contenders are:
Audio Note M7
SY Heretical
a Rankin preamp?
Rozenblit’s Grounded grid

Which of the above, or something else, should best achieve the above priorities?

Thanks kindly
 
#3
If you have enough of a budget for a transformer coupled dht pre I happily 😉 recommend my 26 based, transformer coupled line stage, it has all of the attributes you describe. (Well in my mind anyway :whacko: )

Adaptable to the 01/201 as well, and undoubtedly other similar low voltage, low mu dht's.

The link to the PFO article featuring it is on my site.
 
#8
Hi Rick57

I can recommend Frank's preamp: A 12BH7A WCF with gain slightly less than 1. I build it (including the regulated power supply) and the system (i won't say the preamp) sounded much better than with just a passive stepped attenuator. You can find a lenghty thread searchinf for 12BH7A.

Erik
 
#17
jeff mai said:


It's unity gain and it does nothing to the sound. Why use it?
Click to expand...

To raise and lower volume, switch sources, and drive cables and amp inputs. As a bonus, it breaks up grounding problems. What it does not do is give a characteristic coloration. rick57 wants an effects box, really, and I'm sure that there are plenty of good circuits that could give it to him- I've certainly heard my share of preamps that left distinct fingerprints on the sound...

BTW, it is not restricted to unity gain. A step-up input tranny will give gain and be capable of being optimally loaded.
 
#18
> rick57 wants an effects box, really

Well a mix of no negative effects, and a recognition that there are always trade offs.

Though as a separate issue, to offset the often mediocre SQ of much of the music I listen to, if colorations could be switched in via a different circuit,. .
 
#19
Well, let me be a bit clearer- your recognition that you might not want the sound served "a la nature" is a pertinent one. And despite the shibboleths of "straight wire with gain," there is often a benefit to having the preamp prettify the sound. Were I you (and I congratulate you for recognizing what you really want), I'd look for a circuit that gives a relatively high THD, but heavily oriented toward even order, and monotonically decreasing with increasing order.
 
#20
SY,

I understand the possible benefits and I agree that they are valuable.

My question was more of a philosophical one aimed squarely at the notion of using any unity gain preamp that does nothing to the sound. It has nothing to do with the excellent preamp of your design.

Cheers
 
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