#26 pre amp

[Vinylsavor]

Originally Posted by merlin el mago

So if I use LL1660 & TVC can I avoid the output cap?

Yes, but the last cap in your PSU or reg if you have goes fully into the signal path and will influence the sound. Only the best should be used there

Thomas

[merlin el mago]

Ok thanks for advice Thomas.

Felipe

[Vinylsavor]

Hi!

Originally Posted by coolzero

I tried simple cathode bias and filament bias but end up with battery gird bias because I liked the sound. I initially tried passive LCL as well for PSU. But when used SALAS HVPSU, I felt a big improvement over sound and noise level so started using that.

LCLC is not sufficient filtering for the linestage unless you use very high inductance chokes. The fact that you still had noise confirms that.

best regards

Thomas

[andyjevans]

I have to admit that my LCLC filtering is exactly the same as Rod Coleman's. I don't have an issue myself.

What do you guys think of glow tubes? I've used them in the past, but not sure they are any better than caps and chokes.

Andy

[Vinylsavor]

Hi!

Keep in mind that the sonic influence of the PSU is not the same with each circuit. A LC or RC coupled stage will react very different compared to a transformer coupled stage. It is important to keep the whole system in mind when you evaluate such things. What might work will in one context may not sound as good in another!

Best regards

Thomas

[andyjevans]

Originally Posted by Vinylsavor

Hi!

Keep in mind that the sonic influence of the PSU is not the same with each circuit. A LC or RC coupled stage will react very different compared to a transformer coupled stage. It is important to keep the whole system in mind when you evaluate such things. What might work will in one context may not sound as good in another!

Best regards

Thomas

Yes, that's a good point!

Andy

[coolzero]

Originally Posted by andyjevans

I have to admit that my LCLC filtering is exactly the same as Rod Coleman's. I don't have an issue myself.

What do you guys think of glow tubes? I've used them in the past, but not sure they are any better than caps and chokes.

Andy

What values you use for L1, L2 and C4?

[andyjevans]

Initial capacitor is a 0.1uF Russian teflon. L1 is 10H at 100mA, then 50uF cap, L2 is 15H at 30mA, then 47uf cap. Inside the preamp chassis I have a dropping resistor and then a 10uf cap. All caps are polypropylene motor runs. I have a 25K resistor to ground after L1 for critical inductance.

andy

[Vinylsavor]

Hi!

I use LCLCLC filtering in my preamps. I use large inductances of 50-100Hy. Caps in the range 40-50uF. I want my preamps to be hum free.

The last LC section is separate for each channel.

Ultrapath requires much more ripple free B+ unless it is used in hum cancelling mode which I'm not doing. With conventional circuit you might get away with LCLC, but I'd use much bigger inductances. With the small currents needed by the 26, 100Hy is easily available

Thomas

[coolzero]

Originally Posted by andyjevans

Initial capacitor is a 0.1uF Russian teflon. L1 is 10H at 100mA, then 50uF cap, L2 is 15H at 30mA, then 47uf cap. Inside the preamp chassis I have a dropping resistor and then a 10uf cap. All caps are polypropylene motor runs. I have a 25K resistor to ground after L1 for critical inductance.

andy

I used almost similar configuration earlier (except different cap type) but I could hear slight noise. It almost disappeared with SALAS HV.