Is there a problem that anuyone knows of about using a push pull ot on a single ended amp.
The only reason im asking is the tube im using has a high plate resistance and only the pp trans go high enough.
Also is hammond a good output transformer & what other brands are out there.
Thanks Nick
The only reason im asking is the tube im using has a high plate resistance and only the pp trans go high enough.
Also is hammond a good output transformer & what other brands are out there.
Thanks Nick
I would not go that route, using a P-P OPT for SE application is opening a can of worms.....
What tube are you using ???
WHat operating conditions are you operating this tube at???
What performance are you expecting????
Once this info is known, then some of the members of this forum can chime in on suitable transformer options...
Chris
What tube are you using ???
WHat operating conditions are you operating this tube at???
What performance are you expecting????
Once this info is known, then some of the members of this forum can chime in on suitable transformer options...
Chris
How are you going to run AB1 in single-ended???
In any event, p-p transformers are generally not suitable for SE service except at VERY low powers. The absence of a gap means that the DC will saturate the core.
In any event, p-p transformers are generally not suitable for SE service except at VERY low powers. The absence of a gap means that the DC will saturate the core.
kinda didnt give enough info sorry. the tube is a zero bias triode.
I want to run it at 3000vdc that gives me a max signal plate current of around 350ma requires 12.5 watts rms drive z= 4300 ohms.
Hope to get a useful 200 to 250 clean watts rms more would be better.
If I have to though I can lower the B+ to 2kvdc to lower the z
Nick
I want to run it at 3000vdc that gives me a max signal plate current of around 350ma requires 12.5 watts rms drive z= 4300 ohms.
Hope to get a useful 200 to 250 clean watts rms more would be better.
If I have to though I can lower the B+ to 2kvdc to lower the z
Nick
ok so I'm assuming you cant run ab1 or to unless it's pp with 2 tube.
Forgive my ignorence I'm use to rf and class c .
The spec sheet on the tube refernce to class ab2 for af thats what i'm going by.
Would this be class a
Forgive my ignorence I'm use to rf and class c .
The spec sheet on the tube refernce to class ab2 for af thats what i'm going by.
Would this be class a
Well, you'd have to run class A because this isn't a tuned circuit. That means your efficiency is going to be pretty terrible (25% on a good day, wind at your back, going downhill). And a SE transformer for that current and voltage will cost a fortune, not to mention being too heavy to lift unassisted.
As you've noted, tubes in this class tend to need very high anode loads, which means that the transformers are even more difficult to make without severe bandwidth restrictions.
All of this is a long way of saying:
1. Don't use SE for high powers.
2. Don't use power tubes that require high impedances.
As you've noted, tubes in this class tend to need very high anode loads, which means that the transformers are even more difficult to make without severe bandwidth restrictions.
All of this is a long way of saying:
1. Don't use SE for high powers.
2. Don't use power tubes that require high impedances.
so pp is the way to go I could run it at 1500vdc in push pull and an output transformer isnt a problem or is this a bad idea?
Well, that eases the weight issue, but you'll still have the issue of needing a transformer with a high turns ratio. That's not good for stability or bandwidth.
Given that this is a tube that needs noisy cooling and is not terribly linear, there are better design choices.
Given that this is a tube that needs noisy cooling and is not terribly linear, there are better design choices.
Is that 1600 for a single tube? If so, you need about 6400 for push-pull, which is pretty reasonable.
Now how are you going to manage cooling fan noise?
Now how are you going to manage cooling fan noise?
yes I just rechecked the specs and the numbers per tube. I've also been contimpleting trying a 813 because 4 3-500zg costs $600.
I'm not as concered with fan noise becuase I was plannig on building the amp in a rack box and putting it in a sound proof rack cabinet that I have with nice 6" inch fans in the top.
So tell me this you get better low frequency responce from se or pp.
Nick
I'm not as concered with fan noise becuase I was plannig on building the amp in a rack box and putting it in a sound proof rack cabinet that I have with nice 6" inch fans in the top.
So tell me this you get better low frequency responce from se or pp.
Nick
If "better" means "more accurate," then push pull for sure. 5-10% distortion is not my idea of "accurate," and that's not an unusual number for an SE amp at lower frequencies.
Ok correct me if I'm wrong 'now mind you I ask this just for sheer clarification though' two tubes in parallel cuts the impedance by half doesn't it
Yes, that's right. I'm almost afraid to ask why this question.... (envisioning eight 3-500Z in push-pull parallel)
Jezz if I had millions of dollars maybe but luckly no but could you amagine an pp ot that could handle 2kilowatts. Ya I'd say about 50 pounds of iron.
I'm thinken of a cheaper tube but you have cleared alot of things up so thank you.
I do have 1 more question though in the rf realm you it's easy to figuare you z because your frequency spread is narrow most of the time.
So in audio equpment is the z figuared for the higest frequency or the middle.
Really thanks for the help
I'm thinken of a cheaper tube but you have cleared alot of things up so thank you.
I do have 1 more question though in the rf realm you it's easy to figuare you z because your frequency spread is narrow most of the time.
So in audio equpment is the z figuared for the higest frequency or the middle.
Really thanks for the help
Audio, being broadband, uses things like transformers for impedance matching rather than stuff like pi networks. The nice thing about transformers is that they are inherently broadband (in a general sense). Also, the tube admittances are also relatively constant over the frequency span. So the load calcs are the same at 100Hz and 20kHz. Makes life easy, huh?
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