Punchy 813 Poweramp

ak_47_boy · 2nd January 2007, 04:01 AM

I am looking to build a tube amp for bass in a biamp system. The 813 looks extreemly interesting. I would like between 70-140wpc. I would like strong bass that is punchy. I found these links:

http://www.pmillett.com/813_se_triode_amps.htm
http://members.aol.com/analogengineer/813mat.htm
http://homepages.ihug.co.nz/%7Erwillis/alex/
http://home.zonnet.nl/horneman/813.htm
http://www.izzy-wizzy.com/audio/powamp813.html

When can i add a second 813 in parallel to double the output (only pushpull?)? Assuming PSU can handel it.

What do you think?

thanks

sorenj07 · 2nd January 2007, 05:36 AM

any time you parallel tubes, you double the output and halve the plate resistance.

ak_47_boy · 2nd January 2007, 05:40 AM

Plate resistance would change alot?

ReidK · 2nd January 2007, 07:43 PM

"Halve" means "divide by two" (just like paralleling any two equal resistances.) In this context, yes that's a lot. If you double the number of output tubes, your output transformer would have to present half the load impedance of the single-tube design, in addition to handling twice the power . Many transformers allow the use of a different tap to acheive the correct impedance; the power handling will probably be the chief issue, especially for low frequencies.

Reid

ak_47_boy · 3rd January 2007, 10:08 PM

I did not realy say that right, when i said "plate resistance would change alot?" i was talking about all the values of resistors and capacitors changeing. Can i parrellel on SE? Say i wanted to parallel this scematic: http://homepages.ihug.co.nz/%7Erwill..._schematic.jpg
I would use a 3K transformer?

kevinkr · 3rd January 2007, 10:54 PM

I don't think using a beam power tetrode in SE parallel or not is going to net you the bass you are looking for. The output impedance even in the UL connection is going to be at least a couple of ohms relative to an 8 ohm tap, frankly I suspect higher than that. You would need of feedback to get a reasonable damping factor (say 10) This tube requires a lot of voltage drive as well and plate voltages of around 1KV for good performance.

Why not try something with a couple of parallel 6C33? Low Rp with a properly chosen transformer would allow for low/no feedback operation in SE.

ak_47_boy · 4th January 2007, 12:27 AM

Quote:

Originally posted by kevinkr
I don't think using a beam power tetrode in SE parallel or not is going to net you the bass you are looking for. The output impedance even in the UL connection is going to be at least a couple of ohms relative to an 8 ohm tap, frankly I suspect higher than that. You would need of feedback to get a reasonable damping factor (say 10) This tube requires a lot of voltage drive as well and plate voltages of around 1KV for good performance.

Why not try something with a couple of parallel 6C33? Low Rp with a properly chosen transformer would allow for low/no feedback operation in SE.

I was kind of aiming for a pushpull. What type do you think is better suited to clean powerfull and punchy bass? I am open to al options.

Sheldon · 4th January 2007, 12:32 AM

My initial thought too, that PP would be the choice for your application, but the references you cited are SE amps. Bet Kevin would have a good PP example in your power range.

Sheldon

ak_47_boy · 4th January 2007, 04:20 AM

That would e great if i could get a pp scematic. The only one i could find on the net was 1KW. Thats to big..

kevinkr · 4th January 2007, 01:28 PM

How much power do you need? I've got a couple of possibilities, not available for general consumption, but I'd be willing to share.

2nd January 2007, 04:01 AM	#1
ak_47_boy diyAudio Member Join Date: Sep 2006	Punchy 813 Poweramp I am looking to build a tube amp for bass in a biamp system. The 813 looks extreemly interesting. I would like between 70-140wpc. I would like strong bass that is punchy. I found these links: http://www.pmillett.com/813_se_triode_amps.htm http://members.aol.com/analogengineer/813mat.htm http://homepages.ihug.co.nz/%7Erwillis/alex/ http://home.zonnet.nl/horneman/813.htm http://www.izzy-wizzy.com/audio/powamp813.html When can i add a second 813 in parallel to double the output (only pushpull?)? Assuming PSU can handel it. What do you think? thanks

3rd January 2007, 10:54 PM	#6
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	I don't think using a beam power tetrode in SE parallel or not is going to net you the bass you are looking for. The output impedance even in the UL connection is going to be at least a couple of ohms relative to an 8 ohm tap, frankly I suspect higher than that. You would need of feedback to get a reasonable damping factor (say 10) This tube requires a lot of voltage drive as well and plate voltages of around 1KV for good performance. Why not try something with a couple of parallel 6C33? Low Rp with a properly chosen transformer would allow for low/no feedback operation in SE. __________________ www.kta-hifi.net

4th January 2007, 01:28 PM	#10
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	How much power do you need? I've got a couple of possibilities, not available for general consumption, but I'd be willing to share. __________________ www.kta-hifi.net

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
YAP - Yet Another PowerAmp	syn08	Solid State	315	4th October 2011 11:39 PM
Recomnbed woofers/Mids for punchy yet deep bass?	xenu	Multi-Way	14	21st April 2009 02:32 AM
Worth upgrading cheap av with a punchy driver?	VvvvvV	Subwoofers	2	24th November 2005 01:29 PM

2nd January 2007, 05:36 AM	#2
sorenj07 diyAudio Member Join Date: May 2006	any time you parallel tubes, you double the output and halve the plate resistance.

2nd January 2007, 05:40 AM	#3
ak_47_boy diyAudio Member Join Date: Sep 2006	Plate resistance would change alot?

2nd January 2007, 07:43 PM	#4
ReidK diyAudio Member Join Date: Jan 2006 Location: Los Angeles (a.k.a. Hell on Earth)	"Halve" means "divide by two" (just like paralleling any two equal resistances.) In this context, yes that's a lot. If you double the number of output tubes, your output transformer would have to present half the load impedance of the single-tube design, in addition to handling twice the power . Many transformers allow the use of a different tap to acheive the correct impedance; the power handling will probably be the chief issue, especially for low frequencies. Reid

3rd January 2007, 10:08 PM	#5
ak_47_boy diyAudio Member Join Date: Sep 2006	I did not realy say that right, when i said "plate resistance would change alot?" i was talking about all the values of resistors and capacitors changeing. Can i parrellel on SE? Say i wanted to parallel this scematic: http://homepages.ihug.co.nz/%7Erwill..._schematic.jpg I would use a 3K transformer?

4th January 2007, 12:32 AM	#8
Sheldon diyAudio Member Join Date: Dec 2003 Location: San Diego	My initial thought too, that PP would be the choice for your application, but the references you cited are SE amps. Bet Kevin would have a good PP example in your power range. Sheldon

4th January 2007, 04:20 AM	#9
ak_47_boy diyAudio Member Join Date: Sep 2006	That would e great if i could get a pp scematic. The only one i could find on the net was 1KW. Thats to big..

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

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