#26 pre amp

[martyh]

Thanks for the replies,

After Kevin’s description of the biasing schemes he has tried I will just stick with the grid bias connection. I’m gonna quit rethinking and start soldering. Hopefully I have learned enough by reading this thread and Kevin’s article that I can get it done.

[coolzero]

Originally Posted by martyh

Thanks for the replies,

After Kevin’s description of the biasing schemes he has tried I will just stick with the grid bias connection. I’m gonna quit rethinking and start soldering. Hopefully I have learned enough by reading this thread and Kevin’s article that I can get it done.

Martyh, grid bias which Kevin mentioned, works like charm. Fairly easy to setup. I tried both the biasing methods (cathode and grid with 9V alkaline batteries) and latter is the most sonically superior and least hum. If you check the first page of this thread, I have put the schematic used.

[coolzero]

Just replaced the RIFA 0.15uf coupling cap of the grid bias circuitry with Mundorf RXF 0.1u. Couldn't believe the magic just this simple mod has done. A whole new life to my 26 pre. Tried few different brands/types of caps including Tantalums but this was the best so far. Hope a better cap like Mundorf silver/oil would do more wonder.

Myrtyh, if you are trying the grid bias, spend some on the coupling cap straightaway. Pretty sure you will not regret.

[Curly Woods]

Originally Posted by coolzero

Just replaced the RIFA 0.15uf coupling cap of the grid bias circuitry with Mundorf RXF 0.1u. Couldn't believe the magic just this simple mod has done. A whole new life to my 26 pre. Tried few different brands/types of caps including Tantalums but this was the best so far. Hope a better cap like Mundorf silver/oil would do more wonder.

Myrtyh, if you are trying the grid bias, spend some on the coupling cap straightaway. Pretty sure you will not regret.

Careful there coolzero, some here do not believe that coupling capacitors can affect the sound quality one can achieve. Pure snake oil Enjoy. I bet the 26 does sound heavenly!

[coolzero]

Originally Posted by Curly Woods

Careful there coolzero, some here do not believe that coupling capacitors can affect the sound quality one can achieve. Pure snake oil Enjoy. I bet the 26 does sound heavenly!

I know it is subjective but what I hear is what could believe. 26 certainly does not need any of these because it sounds wonderful with anything but I heard a definite change in the character of sound (in a positive way) specially with Mundorf coupling caps every time I use them. This mod was purely unintentional one and just did because I had a pair of RSX in hand. It may complete snake oil technically about changing different type /brands of coupling caps but I could hear a difference most of the times I do that. Ultimately what we need is best sound possible out of anything, even if it is snake oil;isn't it?

Guys..share your thoughts if you wish..seems to be an interesting topic to discuss..

[bequerel]

Coolzero,

Mighty fine linestage you have there.

Regarding the schematic you posted on the first page of this thread, I do not understand the cathode arrangement. The 26 is a DHT, but the drawing shows an IDHT where a filament heats the catode... or am I misunderstanding?

[coolzero]

Originally Posted by bequerel

Coolzero,

Mighty fine linestage you have there.

Regarding the schematic you posted on the first page of this thread, I do not understand the cathode arrangement. The 26 is a DHT, but the drawing shows an IDHT where a filament heats the catode... or am I misunderstanding?

Sorry for my poor skill of schematic drawing. I didn't have proper software to draw the schematic and barely manage to draw it using a free tool available on the net. Hence don't give much attention to the symbol I used for 26. This final schematic which I used was originated out of valued suggestions provided by Kevin and it proved it's capabilities when I built it.

[bequerel]

Coolzero,
No need to apologize, would have done the schematic drawing much worse mylself!

Btw. what do you use as volume control in this linestage? An ALPs? A TDK?

[coolzero]

This how exactly I connected components on my current 26 pre.

[martyh]

Originally Posted by coolzero

Just replaced the RIFA 0.15uf coupling cap of the grid bias circuitry with Mundorf RXF 0.1u. Couldn't believe the magic just this simple mod has done. A whole new life to my 26 pre. Tried few different brands/types of caps including Tantalums but this was the best so far. Hope a better cap like Mundorf silver/oil would do more wonder.

Myrtyh, if you are trying the grid bias, spend some on the coupling cap straightaway. Pretty sure you will not regret.

Thanks, I’m starting with vitamin Q’s for the inputs. Some people don’t like them but I do. I don’t have nearly the experience substituting parts as the rest of you do but I’ve built whole projects with metal film resistors and modern foil caps and others with carbon resistors and vintage oil caps and the latter gets me much closer to the sound I like. That’s the approach I’m taking this time but since there are only the two input caps it should be pretty easy to experiment. I am hoping though that it sounds so damn good out of the chute I just move on to the next project