How to drive 8 pairs of MJL21193/94? - Page 5

wg_ski · 11th May 2009, 02:39 PM

Quote:

Originally posted by nigelwright7557
I now use +/-60V and that seems to be a lot better.
Sadly the price of electrolytics rockets above 63V.

Amplifier power rockets above 63V, too. And amp rails are never as stiff as you expect them to be based on trafo regulation specs.

tinitus · 11th May 2009, 03:35 PM

LarsClausen(LCAudio) once showed how to use seperate standard +/- supply fore each half of the balanced/bridged amp, using smaller voltage caps
But ending with a single higher voltage cap across + to -
Ground would be sort of floating

nigelwright7557 · 11th May 2009, 03:57 PM

Quote:

Originally posted by wg_ski

Amplifier power rockets above 63V, too. And amp rails are never as stiff as you expect them to be based on trafo regulation specs.

Thats becasue the output power is V squared/ speaker impedance.

destroyer X · 11th May 2009, 04:40 PM

Do you have speaker enougth to all that power?

Will be some special application, alike football field or enormous open air alive performance or something in a such direction?

Man!.... this heatsink cannot hold all that power.

I feel curious....just that.... i have some speaker here, used into automobile, so bad they are(low efficiency) that needs 400 watts RMS to move..is this your case?

Carlos

destroyer X · 11th May 2009, 05:05 PM

I am very curious about yours....please, let me know.

regards,

Carlos

http://www.youtube.com/watch?v=2SBEJffbwHk

sajti · 11th May 2009, 07:30 PM

I want to use it for 2 different application:

- home system to drive my 8ohms Focal loudspeaker, mainly in class A, up to 100W.

- to drive the front, and subwoofer in a party (my subwoofer contains 2x18" Beyma loudspeakers, and can handle 1800W rms)

I know that this heatsink is not enough. This is for test only. I'm not sure the final solution. I have two possibilities:

1, 40cm long heatsink for each module
2, keep this heatsink, and use forced cooling with variable speed fan

Sajti

sajti · 26th August 2009, 08:01 AM

I had no time in the last few weeks, but now I start to do some measurements, and try some other solution.

So, the prototype contains now: 4pairs of MJL21193/94, and NJW0281/0302 as drivers and no predriver. I measured the input impedance, which is 12kohms, with 2ohm load (it means 4ohm nominal load for the bridged amplifier). It's not so hard load, and I can drive it with White follower using ECC99 (150V/18mA anode current). I still working to put it together...

Sajti

AndrewT · 26th August 2009, 08:33 AM

Zin=12k with 2r0 load.
Zin>4k with 2ohm reactive load?
What about Zin dips when abuse occurs?

sajti · 26th August 2009, 08:38 AM

The driver tube can drives 1kohm load with full output swing (60Vpp), so some impedance drop can not be problem. If I use all the output devices (8pairs), there will be no B drop even with 2ohm balanced load.

Sajti

AndrewT · 26th August 2009, 08:55 AM

tell me if this is balderdash.

Maximum output 30Vpk.
Maximum current into 2r0 15Apk.
Maximum current into 2ohm ~45Apk.
Maximum current through each output device ~5.6Apk (during normal use - no abuse).
typical gain @ 5.6Apk ~ 45 to 60.
typical maximum base current ~45Apk/45 ~1Apk.
typical NJW gain @ 0.1Apk to 5Apk, ~constant @ 100.
typical driver base current ~10mA+driver bias ~?mA. Try 20mA
typical impedance 30V/0.02A ~1k5 for normal drive conditions.

11th May 2009, 05:05 PM	#45
destroyer X diyAudio Member Join Date: Feb 2004 Location: Recife - Brasil Northeast	I understand that some applications needs power. I am very curious about yours....please, let me know. regards, Carlos http://www.youtube.com/watch?v=2SBEJffbwHk __________________ Dx Super A - Brazil - Layout Zimmer; http://www.youtube.com/watch?v=yxpYnUA6Bj0

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
mjl21193/94 indestructable??	mikefromaus	Solid State	2	16th January 2008 02:34 PM
FS: MJL21193 and MJL21194 - new	zener_diode	Swap Meet	9	27th December 2007 03:36 AM
MJL21193/21194s	N-Channel	Swap Meet	1	18th September 2005 03:04 AM
MJL21193 and MJL21194	HuntTheShunt	Parts	1	5th December 2004 12:11 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


	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

11th May 2009, 03:35 PM	#42
tinitus diyAudio Moderator Join Date: Nov 2005	LarsClausen(LCAudio) once showed how to use seperate standard +/- supply fore each half of the balanced/bridged amp, using smaller voltage caps But ending with a single higher voltage cap across + to - Ground would be sort of floating

11th May 2009, 07:30 PM	#46
sajti diyAudio Member Join Date: Apr 2003 Location: Vác, Hungary	I want to use it for 2 different application: - home system to drive my 8ohms Focal loudspeaker, mainly in class A, up to 100W. - to drive the front, and subwoofer in a party (my subwoofer contains 2x18" Beyma loudspeakers, and can handle 1800W rms) I know that this heatsink is not enough. This is for test only. I'm not sure the final solution. I have two possibilities: 1, 40cm long heatsink for each module 2, keep this heatsink, and use forced cooling with variable speed fan Sajti

26th August 2009, 08:01 AM	#47
sajti diyAudio Member Join Date: Apr 2003 Location: Vác, Hungary	I had no time in the last few weeks, but now I start to do some measurements, and try some other solution. So, the prototype contains now: 4pairs of MJL21193/94, and NJW0281/0302 as drivers and no predriver. I measured the input impedance, which is 12kohms, with 2ohm load (it means 4ohm nominal load for the bridged amplifier). It's not so hard load, and I can drive it with White follower using ECC99 (150V/18mA anode current). I still working to put it together... Sajti

26th August 2009, 08:33 AM	#48
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Zin=12k with 2r0 load. Zin>4k with 2ohm reactive load? What about Zin dips when abuse occurs?

26th August 2009, 08:38 AM	#49
sajti diyAudio Member Join Date: Apr 2003 Location: Vác, Hungary	The driver tube can drives 1kohm load with full output swing (60Vpp), so some impedance drop can not be problem. If I use all the output devices (8pairs), there will be no B drop even with 2ohm balanced load. Sajti

26th August 2009, 08:55 AM	#50
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	tell me if this is balderdash. Maximum output 30Vpk. Maximum current into 2r0 15Apk. Maximum current into 2ohm ~45Apk. Maximum current through each output device ~5.6Apk (during normal use - no abuse). typical gain @ 5.6Apk ~ 45 to 60. typical maximum base current ~45Apk/45 ~1Apk. typical NJW gain @ 0.1Apk to 5Apk, ~constant @ 100. typical driver base current ~10mA+driver bias ~?mA. Try 20mA typical impedance 30V/0.02A ~1k5 for normal drive conditions.