• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

01A question

Sorry guys while we're on the AZ1 rectifier, what would the ideal Ac v out be from the transformer. Am looking into a CLC or CLCLC stage. Haven't got the chokes so don't know the resistant. Besides I've no experience with the AZ1 don't know what the voltage drop be like under load. Chokes will be 10 henries or more

Thks again
 
My PSU for my 4P1L SE has two AZ1 mesh in parallel. It's 300v AC into a hybrid (Graetz) bridge. This gives me 265v after CLCLC. Chokes are about 100 ohms each, caps 40uF polypropylene, and the load of the amp is around 150mA. So there's quite a big drop with the AZ1s. But the current for an 01A preamp is tiny so it would be a different story. Choke input would be the way to go.
 
There are theories on why globes sound better than ST or later types. Most revolve around the globe having less mica support inside the bottle. Mica is known to outgas over time which could result in the tube with more mica having a poorer vacuum.

Other think that the less supported structure inside the globe will vibrate more and through microphonics impart a euphony to the sound. Personally I don't like the sound of microphonics so this seems less likely to me.
 
Yes, it was the bulit-in instrument in the other side of the large workroom.

The extra load was only about 400pF//1MOhm.



IMHO 201a internal resistance a bit high and its driving capacity is limited even with CCS or gyrator loading.


Hi Bela,
In my experience, In a hybrid mu-follower with gyrator load you can get the -3dB @ 100KHz with 100k load. The treble response is noticeable and output impedance is lower, even when filaments are starved.
Cheers
Ale
 
Ale brought round his preamp - the one on his blog - and we listened to it in my system. I remember his power supply was shared with his 4P1L preamp but not what was in it. He probably did have a Salas reg, but that would come after the rectifier. Use an AZ1 mesh if you want the best.


Indeed, HT is shared as have limited space and a good HT supply in the 4P1L already available. No need for a shunt regulator if the HT filtering is good as the gyrator provides a good PSR. I have a choke input LCLC using damper tubes and using film caps. I think the diagram is somewhere in my blog. Best investment is on the LT supply and in the Rod Coleman regulators in my experience.
Ale
 
maybe a dualmono supply like in my 10 dht pre ?
dead quiet about 110µV noise on outputs, input terminated.
-3 db at 63 khz, 10v peak out when 2vpeak in, thd at 10v peak 0,023% at 1 khz, 0,03% at 20 khz

Rods excellent filamentsupply, of course!
 

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It would seem that the transformer would greatly influence the sound of the 26 so a comparison to the 01a would be misleading. Have you guys tried the 26 with a mu follower?

Not a constant voltage mu follower like Ale, but I use a constant current mu follower in my 26 preamp. No issues with soft treble, plenty of air and 3-D imaging. The 26 feeds an autoformer (Slagle silver-wound) in parafeed.