Zen Output Question

stefanobilliani · 17th January 2008, 05:00 PM

What happens connecting the Zen output this way?

wuffwaff · 18th January 2008, 09:43 AM

Hi,

just try. DC shoud be the same on both sides of the speaker once powered.

Don´t know about the turn on thump though......

William

stefanobilliani · 18th January 2008, 01:06 PM

Hello William ,

I did try . Dc ok on both sides , no turn on thump.

Different sound , less gain , higher distorson , were the impressions ...

Babowana · 18th January 2008, 02:09 PM

The speaker does not see ripple voltage?
No hum?

GRollins · 18th January 2008, 03:09 PM

I see at least one potential problem. C1 and C2 will not divide the rail voltage evenly. Assuming that they're normal electrolytics, and rated +10-20% or some such, you should see that the voltage divides unevenly according to the ratio of their actual capacitance. The usual solution is to use a resistive divider to force equal voltage across the two capacitors. If you can manage to get the amp to set an equal DC potential--and hold it--you might have a viable circuit.
In principle you can delete the Source resistor under the MOSFET.

Grey

stefanobilliani · 18th January 2008, 04:16 PM

Quote:

Originally posted by GRollins
C1 and C2 will not divide the rail voltage evenly.The usual solution is to use a resistive divider to force equal voltage across the two capacitors.

Grey

Well they do and hold the point and dont seem to give problems . The speaker see just fiew millivolt if the DC output point is at half the rail .I was thinking of the resistive divider too and I am sure it may help in case the dc point of the amplifier isnt half the rail ( Zen V9 for example )

Regarding the possible hum , It is easy to understand that if the amp itself is well filtered ,to add two more capacitors par rail cant hurt . Infact I didnt noticed any additional hum testing that situation .

Babowana · 18th January 2008, 04:19 PM

Great!

wuffwaff · 18th January 2008, 04:52 PM

Hi,

I thought DC would be set by the left side of the amp. The speaker is just a resistor connecting the drain with the to caps on the right side. So DC will be just the same value as on the left and the offset will be zero.

William

stefanobilliani · 18th January 2008, 05:02 PM

Quote:

Originally posted by wuffwaff
Hi,

I thought DC would be set by the left side of the amp. The speaker is just a resistor connecting the drain with the to caps on the right side. So DC will be just the same value as on the left and the offset will be zero.

William

Indeed it is like that . But guess is not pratical to use the (sensitive ) speaker as a dc resistor ...

GRollins · 18th January 2008, 05:10 PM

Good. I think wuffwaff is on the right track in that the circuit itself is able to source/sink sufficient current that it holds the node between the capacitors steady.
Don't be surprised if you get a moderate-sized pop through the speaker if you connect the speaker while the amplifier is already on. The caps will have charged to some arbitrary voltage and they'll have to equalize with the circuit through the speaker. Connecting the speaker only while the amp is off will circumvent this problem.
The resistive divider probably won't accomplish much the way things are going, so just leave it off.

Grey

18th January 2008, 09:43 AM	#2
wuffwaff diyAudio Member Join Date: Aug 2001 Location: Ingolstadt Germany	Hi, just try. DC shoud be the same on both sides of the speaker once powered. Don´t know about the turn on thump though...... William __________________ een ooievaar is geen konijn want zijn oren zijn te klein!

18th January 2008, 04:52 PM	#8
wuffwaff diyAudio Member Join Date: Aug 2001 Location: Ingolstadt Germany	Hi, I thought DC would be set by the left side of the amp. The speaker is just a resistor connecting the drain with the to caps on the right side. So DC will be just the same value as on the left and the offset will be zero. William __________________ een ooievaar is geen konijn want zijn oren zijn te klein!

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
Output Noise question	ianc13	Tubes / Valves	2	20th August 2007 10:48 AM
Calculating SE Output Question	Trout	Tubes / Valves	9	15th March 2007 04:12 AM
nub question about output caps	MEXXX	Chip Amps	3	10th November 2004 01:46 AM
The output question of GC	digi01	Chip Amps	1	29th January 2004 12:28 AM
OTL Output Cap Question	Andrewbee	Tubes / Valves	6	12th January 2004 07:45 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

18th January 2008, 01:06 PM	#3
stefanobilliani diyAudio Member Join Date: Jun 2002 Location: Italy	Hello William , I did try . Dc ok on both sides , no turn on thump. Different sound , less gain , higher distorson , were the impressions ...

18th January 2008, 02:09 PM	#4
Babowana Formerly "jh6you". R.I.P. Join Date: Jul 2006	The speaker does not see ripple voltage? No hum?

18th January 2008, 03:09 PM	#5
GRollins diyAudio Member Join Date: Feb 2001 Location: Columbia, SC	I see at least one potential problem. C1 and C2 will not divide the rail voltage evenly. Assuming that they're normal electrolytics, and rated +10-20% or some such, you should see that the voltage divides unevenly according to the ratio of their actual capacitance. The usual solution is to use a resistive divider to force equal voltage across the two capacitors. If you can manage to get the amp to set an equal DC potential--and hold it--you might have a viable circuit. In principle you can delete the Source resistor under the MOSFET. Grey

18th January 2008, 04:19 PM	#7
Babowana Formerly "jh6you". R.I.P. Join Date: Jul 2006	Great!

18th January 2008, 05:10 PM	#10
GRollins diyAudio Member Join Date: Feb 2001 Location: Columbia, SC	Good. I think wuffwaff is on the right track in that the circuit itself is able to source/sink sufficient current that it holds the node between the capacitors steady. Don't be surprised if you get a moderate-sized pop through the speaker if you connect the speaker while the amplifier is already on. The caps will have charged to some arbitrary voltage and they'll have to equalize with the circuit through the speaker. Connecting the speaker only while the amp is off will circumvent this problem. The resistive divider probably won't accomplish much the way things are going, so just leave it off. Grey

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