more output transformer questions - Page 2

SY · 12th January 2007, 08:26 PM

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.

nhuwar · 12th January 2007, 08:30 PM

at 1500 volts the z= is 1600 thats not to high

nhuwar · 12th January 2007, 08:31 PM

I've just always been hung up on big power tubes thats all

SY · 12th January 2007, 08:37 PM

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?

nhuwar · 12th January 2007, 08:53 PM

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

SY · 12th January 2007, 09:06 PM

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.

nhuwar · 12th January 2007, 09:40 PM

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

SY · 12th January 2007, 10:53 PM

Yes, that's right. I'm almost afraid to ask why this question.... (envisioning eight 3-500Z in push-pull parallel)

nhuwar · 12th January 2007, 11:58 PM

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

SY · 13th January 2007, 12:11 AM

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?

12th January 2007, 08:26 PM	#11
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	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. __________________ If there's a sucker born every minute, where do the rest of them come from?

12th January 2007, 08:37 PM	#14
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	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? __________________ If there's a sucker born every minute, where do the rest of them come from?

12th January 2007, 09:06 PM	#16
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	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. __________________ If there's a sucker born every minute, where do the rest of them come from?

12th January 2007, 10:53 PM	#18
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	Yes, that's right. I'm almost afraid to ask why this question.... (envisioning eight 3-500Z in push-pull parallel) __________________ If there's a sucker born every minute, where do the rest of them come from?

13th January 2007, 12:11 AM	#20
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	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? __________________ If there's a sucker born every minute, where do the rest of them come from?


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12th January 2007, 08:30 PM	#12
nhuwar diyAudio Member Join Date: Jan 2007 Location: Cypress Texas	at 1500 volts the z= is 1600 thats not to high

12th January 2007, 08:31 PM	#13
nhuwar diyAudio Member Join Date: Jan 2007 Location: Cypress Texas	I've just always been hung up on big power tubes thats all

12th January 2007, 08:53 PM	#15
nhuwar diyAudio Member Join Date: Jan 2007 Location: Cypress Texas	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

12th January 2007, 09:40 PM	#17
nhuwar diyAudio Member Join Date: Jan 2007 Location: Cypress Texas	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

12th January 2007, 11:58 PM	#19
nhuwar diyAudio Member Join Date: Jan 2007 Location: Cypress Texas	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

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