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preamp kit?

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Burnedfingers

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Joined 2002
While I have no quibbles with that straight forward 6SN7 design, I reiterate that the appropriate gain structure must be determined 1st. Remember the previous remarks about "hair trigger" and a SS line stage. My gut feeling is that a "unity" gain design is going to be the appropriate choice. FWIW, I've got some ideas about 10M45S loaded ECC99 cathode followers that might be suitable.
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Like I mentioned in a post above I made this line stage. I have used it with a number of SS amplifiers without any "hair trigger" effects. It is a very natural sounding and certainly better than the "kits" one might come across. Note that its not unity gain but in my humble opinion based on the fact I use mine unity gain is not a necessity. I have used mine with a number of both commercial amplifiers and consumer (home) amplifiers. It has been used with SS amplifiers with sensivity of .5 to 2.0v without problems. IT is very manageable gain wise as designed.
 

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E

Evenharmonics

Banned
Joined 2007
burnedfingers said:
Like I mentioned in a post above I made this line stage. I have used it with a number of SS amplifiers without any "hair trigger" effects. It is a very natural sounding and certainly better than the "kits" one might come across. Note that its not unity gain but in my humble opinion based on the fact I use mine unity gain is not a necessity. I have used mine with a number of both commercial amplifiers and consumer (home) amplifiers. It has been used with SS amplifiers with sensivity of .5 to 2.0v without problems. IT is very manageable gain wise as designed.
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Is this the PS for it?
 
E

Eli Duttman

Member
Joined 2004
R-Carpenter said:
NM, I see a 10k ohm even cheaper.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=023-530
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Unfortunately, that pot. has a linear taper, which makes it unsuitable. :(

"Rat Shack" catalog # 271-1721 is suitable and costs $2.99 each. While your local R/S may not have stock on hand, they can get 'em in quickly.

At $1.40 each, Mouser part # 31VJ401-F is perfect. If you can bundle other appropriate purchases, this is the obvious choice.
 
E

Eli Duttman

Member
Joined 2004
BTW whats the difference between this pot and the linear one?
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Hearing is exponential, not linear. It takes a 10X increase in power to achieve a 2X difference in observed volume level. Volume control pots. have a log., AKA audio, taper in the variation of the resistance to match hearing. A linear taper pot. would be scrunched up on the dial, not nicely spread out.

OTOH, linear taper pots. are appropriate in hum balance and measurement trimming situations. It's a matter of "horses for courses".
 
B

Burnedfingers

Member
Joined 2002
A linear taper pot. would be scrunched up on the dial, not nicely spread out.
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I don't know about you but I for one don't look at the control to see how far I have turned it. I'm generally quite happy if I turn the control and get a clean clear action as a result. From the graph I posted in a prior post you are clearly correct in the amount you turn the control will differ. one control will have to be turned farther to reach the 50% point. In reality as I see it the control still functions and will still provide ample control and there will be no sonic differences between the two controls.
There are some that are probably willing to jump in here and tell us that our controls should be junked in favor of some high dollar resistive stepped controls and that probably has some merit.

The way I see the preamp thing is quite different than maybe others view it. As long as I can get the control I want out of a particular line stage then I'm happy. With respect to the gain or lack of I view the volume control as the factor to help me compensate for the lack of or abumbance of gain. I only situation that I have gotten into where I had too much gain was when I built a 6Au6/5687 Aikido line stage. It sounded great but was hair trigger with the gain.

How about we move forward now and go back to suggestions for preamps/line stages that the thread asked for. Your point is well taken with respect to the amount of gain available from a CD player. I for one happen to like the flair that different line stages have on the quality of the program input to them. Maybe that is also why there are so many different Power Amps for example. They vary in circuit design and power and that difference is heard by us the listeners.

Just my .02:)
 
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Eli Duttman

Member
Joined 2004
Could someone suggest an easier power supply to build to power Franks line stage?
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That circuit requires 250 VDC, for the B+ rail. Grienacher ("full wave") voltage double the O/P of a Triad N-68X isolation trafo. Use a Maida style regulator to lock the rail at 250 VDC.

A nice way to get GOOD signal tubes for that design is to use 14N7s. The 14N7 is a "12" V. heater, Locktal based, twin triode that's electrically equivalent to the 6SN7. Some Sylvania made 6SN7s enjoy a sterling reputation. AFAIK, regardless of label, only Sylvania's Emporium, PA plant made Locktals, in the US. The Locktals were fabricated in the 1940s and early 1950s. They are the real deal, at a very attractive price.
 
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