Odd's n Ends Revisited 6V6 SE amp

Sparky OR · 10th March 2006, 01:31 AM

Anyone built the amp in 9/05 Audio Express by Graham Dicker. It is a 6V6 SE amp driven by a 12AX7 with potentiometers of 5k for the driver cathode and 1meg for the anode. I built it, because it seemed like a good way for a relative newbie to look at how these variables effect the sound. I used an old 5k SE OPT from a Curtis Mathis hi-fi. Sounds ok, and varying the cathode seemed to have lots more effect than varying the load. I used a cheapie Elenco function generator and an old Hewlett Packard scope to see the output results into an 8 ohm resistor. The amp did not have anything close to a square wave output an any freguency from 100 to 10khz. But when I added a feedback resistor of 6.8k bypassed by a 100pf cap I could get square wave out without too much "ringing?". Is square wave output indicative of anything relative? Or is it not worth chasing down?
Thanks

DigitalJunkie · 10th March 2006, 01:55 AM

Square wave response is worth chasing down,it's great for tuning the feedback network,among other things.

Tubes4e4 · 10th March 2006, 06:54 AM

Also, square waves are very useful to test and optimize stability at complex loads. And they come in handy to determin bandwidth (upper and lower -3dB points) fast and easy.

Tom

10th March 2006, 01:31 AM	#1
Sparky OR diyAudio Member Join Date: Jun 2003 Location: Eugene, Oregon	Odd's n Ends Revisited 6V6 SE amp Anyone built the amp in 9/05 Audio Express by Graham Dicker. It is a 6V6 SE amp driven by a 12AX7 with potentiometers of 5k for the driver cathode and 1meg for the anode. I built it, because it seemed like a good way for a relative newbie to look at how these variables effect the sound. I used an old 5k SE OPT from a Curtis Mathis hi-fi. Sounds ok, and varying the cathode seemed to have lots more effect than varying the load. I used a cheapie Elenco function generator and an old Hewlett Packard scope to see the output results into an 8 ohm resistor. The amp did not have anything close to a square wave output an any freguency from 100 to 10khz. But when I added a feedback resistor of 6.8k bypassed by a 100pf cap I could get square wave out without too much "ringing?". Is square wave output indicative of anything relative? Or is it not worth chasing down? Thanks __________________ Wish I'd studied this stuff with as much interest 30 years ago!

10th March 2006, 06:54 AM	#3
Tubes4e4 diyAudio Member Join Date: Jul 2005 Location: Leverkusen	Also, square waves are very useful to test and optimize stability at complex loads. And they come in handy to determin bandwidth (upper and lower -3dB points) fast and easy. Tom __________________ If in doubt, just measure.

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
Pros and cons of Cascoded front ends	Original Burnedfingers	Tubes / Valves	64	15th December 2011 10:21 PM
Linkwitz ASP PCB's, and other odd's and ends	Tristanc1	Swap Meet	11	27th January 2007 12:29 AM
Need help with top ends.	Socaflex	Multi-Way	2	11th June 2006 08:48 PM
odds and ends Audax drivers	Matt D	Swap Meet	0	5th November 2003 03:38 AM
Phono Leads, Wht have plugs on both ends?	mcyates	Car Audio	23	3rd April 2003 04:40 PM

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

10th March 2006, 01:55 AM	#2
DigitalJunkie diyAudio Member Join Date: Apr 2003 Location: Portland,Oregon Blog Entries: 4	Square wave response is worth chasing down,it's great for tuning the feedback network,among other things.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)