Aikido using a #26 tube?

[Original Burnedfingers]

Ok, given the formula for figuring the second half of an Aikido circuit could a #26 Aikido be made? Anyone that has played with a #26 tube can tell you of the hum associated with it and the need for a battery heater supply.

Would the Aikido circuit therefore be capable of nulling the hum factor without using the battery and charger setup?

Wouldn't this make a nice diy project?

[kevinkr]

check out my article on a 26 transformer coupled pre-amp at Positive Feedback online or go to my website where you will see most of the sameinformation..

http://www.kta-hifi.net/

The problems you are likely to have with the 26 revolve around its high microphony, doing good 1.5V dc filaments supplies is relatively easy.
Transformer coupling works very well with this type and because of the low overall gain mechanical disturbances are not amplified as much as would be the case for RC coupled designs.

I would seriously recommend anyone using these or the 01A mount them on a mechanically isolated (soft rubber bushings) subchassis in their pre-amp design.

Note that they are also quite sensitive to external electrostatic fields and benefit from shielding. (I use cheap copper foil cans around mine.)

Kevin

[andyjevans]

Anyone that has played with a #26 tube can tell you of the hum associated with it and the need for a battery heater supply.>

Well, I thought that until I connected one side of my balanced 26 line stage to SLA batteries and the other side to a Thurlby Thandar PL154 bench power supply (0-15v, 4A). On my system hum was practically non existant on the bench supply and the sound quality was virtually identical. My speakers are Monacor SPH-130AL single aluminium 5" drivers, sensitivity listed at 88db. the line stage handles the output from my DAC digital board.

So, in these circumstances, I feel confident you could use a well filtered DC supply. My line stage is balanced - no idea if that lowers hum but I doubt it. There is a very low level of hum, by which I mean barely audible with your ear against the cone. Whether this would be a worry on a high efficiency horn I can't say. No hum on the batteries. Andy

[Original Burnedfingers]

Gee, I must be doing something all wrong. Even with a battery I was unable to get rid of the hum. The hum was there if I used a regulated supply or battery. There is a chance I may be hearing more noise because my speakers are in excess of 100db 1w 1m.
Even with over 100,000 mfd of cap I still had hum so I gave up on it.

[Original Burnedfingers]

http://home.pacifier.com/~gpimm/battery%20charger.gif

This is an example of someone elses need for the battery charger and battery setup when trying to tame the #26 hum problem.

[Original Burnedfingers]

http://vinyl.and.triodes.net/diy/26_preamp/26pre.htm

And this

[Giaime]

Originally posted by burnedfingers
my speakers are in excess of 100db 1w 1m.

Whoa are you into horns? I like them, if only I could afford some...

[Original Burnedfingers]

My speakers are 3 way and have horn HF and Mid.

[kevinkr]

My speaker system is the old JBL Rhodes C37 cabinet with 075 horn tweeter and D130 15" woofer. The Rhodes cabinet is a reflex design, overall efficiency is well over 100dB, no audible hum from the pre-amp with my 300B se amplifier which has around 22dB of gain.

You can definitely get quiet out of a 26, putting an electrostatic shield around it may help.. You can make one to try out of tin foil.. LOL

edit: fix my usual stupid typos

[Original Burnedfingers]

Kevin,

Do I have to use the UTC HA 133 transformers or can I use a choke or plate resistor? The reason is that I am finding the HA133 is very hard to come by.

Thanks