Audioromy fu-29 - push pull! - Page 2

milosz · 14th June 2011, 08:55 PM

Yes it's true that the tube's power capability is fixed, based on the tube design / construction. However, a lower feedback design will have more distortion as you ask the tube for more power- while a higher feedback design will let you push the tube harder. If you arbitrarily set 1% THD as the maximum allowable distortion level, the low NFB design will produce less power at that limit.

Here you can see that you can get about 3 watts at 8 ohms at 1% THD with high negative feedback, and less than 2 watts at 1% THD without NFB.

Cayin A-300B, 4 ohm tap, high negative feedback, distortion (%)vs 1kHz continuous output power into (from bottom to top at 1W): 16, 8, 4, 2 ohms, one channel driven.

Fig.7 Cayin A-300B, 4 ohm tap, zero negative feedback, distortion (%)vs 1kHz continuous output power into (from bottom to top at 1W): 16, 8, 4, 2 ohms, one channel driven.

Jeb-D. · 14th June 2011, 09:59 PM

Ok, you are correct if using the 1%THD rating for output power. I was reffering to maximum output (clipping).

milosz · 30th January 2013, 06:10 PM

This amp has been in daily use for about 2 years now, filament on one 6N1 failed (opened) so replaced that tube.

Good reliability.

30th January 2013, 06:10 PM	#13
milosz diyAudio Member Join Date: Oct 2006	Long term reliability Audioromy FU-29 amplifier This amp has been in daily use for about 2 years now, filament on one 6N1 failed (opened) so replaced that tube. Good reliability.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
"Push-Pull" for push und "Push-Pull" for pull (like Gamnut) - whats the right name?	tiefbassuebertr	Solid State	70	15th August 2012 08:08 PM
Yet another Push-Pull	croccodillo	Solid State	3	2nd October 2009 12:24 PM
modify parallel push-pull EL84 to single push-pull	chungtat	Tubes / Valves	12	3rd November 2005 11:25 PM
Push Pull	bellx	Solid State	3	25th January 2004 10:59 AM
Double push-pull versus single push-pull	jraraujo	Tubes / Valves	19	19th October 2002 12:23 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

14th June 2011, 08:55 PM	#11
milosz diyAudio Member Join Date: Oct 2006	Yes it's true that the tube's power capability is fixed, based on the tube design / construction. However, a lower feedback design will have more distortion as you ask the tube for more power- while a higher feedback design will let you push the tube harder. If you arbitrarily set 1% THD as the maximum allowable distortion level, the low NFB design will produce less power at that limit. Here you can see that you can get about 3 watts at 8 ohms at 1% THD with high negative feedback, and less than 2 watts at 1% THD without NFB. Cayin A-300B, 4 ohm tap, high negative feedback, distortion (%)vs 1kHz continuous output power into (from bottom to top at 1W): 16, 8, 4, 2 ohms, one channel driven. Fig.7 Cayin A-300B, 4 ohm tap, zero negative feedback, distortion (%)vs 1kHz continuous output power into (from bottom to top at 1W): 16, 8, 4, 2 ohms, one channel driven.

14th June 2011, 09:59 PM	#12
Jeb-D. diyAudio Member Join Date: Nov 2005 Location: SoCal	Ok, you are correct if using the 1%THD rating for output power. I was reffering to maximum output (clipping).