Making sense of the Aikido calculations?

[SY]

You don't want to breach Vhk(max) and you want to use the same type on top and bottom. Empirically, I've found that section to section matching within twin triodes is no better or worse than section to section matching between twin triodes.

 

[fdegrove]

Hi,

Empirically, I've found that section to section matching within twin triodes is no better or worse than section to section matching between twin triodes.

Depends on how good the original supplier is really.
If they selected them for you then you're probably O.K.
Especiallt if you plan on using high gm triodes matching the ones you want to use in a circuit a la Aikido isn't a bad idea. Makes life a lot easier especially if you don't have a o'scope to see what's going on IMO.

Ciao,

 

[ErikdeBest]

Maybe my posts where a bit off topic, but can someone comment on the questions posed?

Erik

 

[SY]

Erik, that should work, but in reality, the PSR of cathode followers is good enough that you don't have to unless you have got a really noisy supply line. With modern power supply caps and regulators, it's very easy and very inexpensive to make a quiet supply.

 

[arnoldc]

jojo, i made that suggestion because you stipulated that you're going to use 12SN7 all the way. EVEN if you'll be using different tubes for the first and second stages, my suggested scheme will still work. I don't see a reason why not, and with more than two years my SRPP has been configured that way, I still don't see why not.

ps.

jojo, your last post suggested you're dizzy now let me explain

Tube No. 1, Triode #1 = 1st BOTTOM stage, Triode #2 = 2nd BOTTOM stage
Tube No. 2, Triode #1 = 1st UPPER stage, Triode #2 = 2nd UPPER stage

Tube No. 2 heater is elevated 80V
Tube No. 1 heater is optionally elevated

pps.

the thread is about the ECC88 buffer with an active load used in the tube-buffered gainclone amp in the chipamp section. i remember the author saying that the datasheet must be checked for the proper cascode manner.

That's a 6922, and I think I've stared long enough on my RCA datasheet, and a couple of other datasheets, and there is no mention of that "order". It's like saying there is a proper order for using an OPA2134 sections.

 

[JojoD818]

jojo, i made that suggestion because you stipulated that you're going to use 12SN7 all the way. EVEN if you'll be using different tubes for the first and second stages, my suggested scheme will still work. I don't see a reason why not, and with more than two years my SRPP has been configured that way, I still don't see why not.

sorry if I gave the wrong impression that I will only use 12sn7s, well I want to maximize my Aikido like everybody else by trying different tubes. i was inspired by JB's blogs regarding the use of same pin different mu tube in the first stage.

thanks for clearing that up, I'm not dizzy anymore.

It's like saying there is a proper order for using an OPA2134 sections.

exactly! I thought maybe there is a science behind it, maybe not. at least I got it off of my head.

Thanks!

You don't want to breach Vhk(max) and you want to use the same type on top and bottom. Empirically, I've found that section to section matching within twin triodes is no better or worse than section to section matching between twin triodes.

I'll keep that in mind always and will elevate my heaters around 80V so that the top and bottom tubes donot breach Vhk(max).

Thanks!

 

[arnoldc]

sorry if I gave the wrong impression that I will only use 12sn7s, well I want to maximize my Aikido like everybody else by trying different tubes. i was inspired by JB's blogs regarding the use of same pin different mu tube in the first stage.

and will still work. example: 6922 first stage, 5687 second stage

First stage:

6922 Tube #1, 1st Triode lower tube, right channel; 2nd triode lower tube, left channel
6922 Tube #2, 1st triode upper tube, right channel; 2nd triode upper tube, left channel; heater elevated

Second stage:

5687 Tube #1, 1st Triode lower tube, right channel; 2nd triode lower tube, left channel
5687 Tube #2, 1st triode upper tube, right channel; 2nd triode upper tube, left channel; heater elevated

 

[JojoD818]

Thanks arnoldc, I'll implement that in my planned peanut tube version. Will try JB's and SY's approach in my octals first.

 

[Burnedfingers]

Could you use a 6sn7 as the input tube and 6AS7 as the 2nd tube?

 

[Burnedfingers]

Would this result in a line stage with lower output?

 

[Bas Horneman]

Could you use a 6sn7 as the input tube and 6AS7 as the 2nd tube?

Yes, I think John even has an example of the 6AS7 in last position.

 

[Burnedfingers]

Hi Bas,

Do you happen to have any of the Aikido boards left?

 

[Bas Horneman]

Hi Joe,

No...sorry. And I don't want to have new ones made because JB sells boards now and he is the "daddy" of the Aikido.

Regards,
Bas

 

[Andypairo]

Hi Bas,

Do you happen to have any of the Aikido boards left?

I have 2 novals and a power supply that I (probably) won't be using.

Mail me if interested.

Cheers

Andrea

 

[JojoD818]

Hi guys,

This is JB's octal pcb. http://www.tubecad.com/2006/05/blog0064.htm

Are those 1/4 watt resistors on the pcb?

Also, since I am in the process of upgrading my transformer, I would like to install a simple series pass regulator (using a bjt transistor with Vce of 500V).

Would it make more sense (noise wise) to use a string of 24V zeners to reach 300V, instead of using 3 series 100V zeners?

Lastly, since the triodes of V1 are on top of each other, if V1 is run at 10mA, does this mean that it is for both triode of V1? And if V2 is also at 10mA, this means 20mA per channel right?

Thanks