It is currently Thu Nov 15, 2018 3:43 pm

All times are UTC - 8 hours




 Page 1 of 1 [ 10 posts ] 
Author Message
 Post subject: ZPA 0.3 and 0.5 output testing
PostPosted: Sun Aug 18, 2013 3:09 pm 

Joined: Thu Dec 13, 2012 4:24 pm
Posts: 71
Location: PA
I did more testing with the ZPA's. The two that I tested are a v1 0.3 and 0.5. Both have had v2 upgrades and capacitor replacement. Both channels (one amplifier at a time) are measured at the same time (with only one channel driven output is higher, which would give a false two channel output test) with two 400W 4ohm non-inductive dummy load resistor banks. I also used two DMM to measure individual channel output and a DC clamp meter to measure DC input current. I used a 10v line driver on the rca input side. I did not test the output of the line driver although I did not have the gain adjusted to max.

My left channel resistor bank was about 1.17 ohms higher than the right during testing (after they warmed up). Even with a fan on both banks the left got much hotter. This caused the output for the left channel on both the 0.5 and 0.3 were slightly less than the right (at least I think that is why).

ACV and DC current is measured at max gain under clipping. The gains are adjusted higher at 14V testing. This gain setting at 12V will clip the output. Other amp I have tested showed the same gain setting gave non-clipped output at both 12V and 14V. Unique?

Testing was done with a 1Khz sine wave.

0.5
DCV battery 11.95
ACV(L)28.35 or 200.9wrms
ACV(R)27.6 or 190.44wrms
DC current 59.45A and 3.3A at idle

0.5
DCV battery 13.9
ACV(L)34.82 or 303.1wrms
ACV(R)35.11 o 308.18wrms
DC current 74.5A and 5.75A at idle


0.3
DCV battery 12.29
ACV(L)24.0 or 144wrms
ACV(R)23.43 o 137wrms
DC current 39.7A and 2.77A at idle

0.3
DCV battery 14.15
ACV(L)26.94 or 181.4wrms
ACV(R)28.42 or 201.9wrms
DC current 46.12A and 3.4A at idle

***I only did one short test per channel. Averaged multiple short testing bursts with cooler resistor banks might yield slightly different results but I doubt it will be a difference you could hear.

Both amps gave considerable more output at 12V then rated. Both amps measured the same as manufacturer specs at 14V. I also had to readjust the gain settings on the amplifiers for 12v and 14v testing. If I used the same gain setting at 12v that I used at 14v the amplifiers would clip hard, interesting. I would suspect 4ohm mono is rated. I will test this with my other two 0.5's when I get the back from being restored and upgraded.

**Note** When using an ipod touch (0.7v max output) as the source without a line driver I had very low output. I was not able to get either amp to clip and at max gain they had a max output under 5wrms per channel. Additional testing in the future will include a minimal input voltage required to drive these amplifiers to clipping.


Offline
 Profile  
 
 Post subject: Re: ZPA 0.3 and 0.5 output testing
PostPosted: Sun Aug 18, 2013 4:44 pm 

Joined: Thu Dec 13, 2012 4:24 pm
Posts: 71
Location: PA
I also plan on testing this with a pink noise signal versus a sine wave. I have a feeling that the amperage draw on a 1khz sine wave will be higher than that on music.


Offline
 Profile  
 
 Post subject: Re: ZPA 0.3 and 0.5 output testing
PostPosted: Thu Aug 29, 2013 2:56 pm 

Joined: Thu Dec 13, 2012 4:24 pm
Posts: 71
Location: PA
49 views and no replies. There will be no point in me posting further testing on this forum


Offline
 Profile  
 
 Post subject: Re: ZPA 0.3 and 0.5 output testing
PostPosted: Thu Aug 29, 2013 3:02 pm 

Joined: Sun May 06, 2012 8:01 am
Posts: 1652
While it may be slightly different with sine waves I highly doubt you'll be able to hear any difference in balance with music and a few watts. Also did you try matching them with the gains once your feeding the sine wave? Or does it chance/vary with time/heat.

The ZPA0.5 I have draws 4.7amps at idle and have heard/read it can draw around 7-8 at idle.

Have you checked the DC offset for the channels to see what they measured and if you could slightly adjust it (pain in the ass as those pots are not easy to adjust....no wonder my friend suggested I replace them with 10-turn pots.)



The ZPA 0.5 has the ability to supply 160v (peak to peak), so the 1600watt at 4ohms is pretty realistic and accurate with proper electrical system and line driver.


Offline
 Profile  
 
 Post subject: Re: ZPA 0.3 and 0.5 output testing
PostPosted: Thu Aug 29, 2013 4:28 pm 

Joined: Thu Dec 13, 2012 4:24 pm
Posts: 71
Location: PA
trickyricky wrote:
While it may be slightly different with sine waves I highly doubt you'll be able to hear any difference in balance with music and a few watts. Also did you try matching them with the gains once your feeding the sine wave? Or does it chance/vary with time/heat.

I gain set the gains to at slightly under visual clipping. My DSO Nano has a small screen so there could be a margin of error there.

The ZPA0.5 I have draws 4.7amps at idle and have heard/read it can draw around 7-8 at idle.

Have you checked the DC offset for the channels to see what they measured and if you could slightly adjust it (pain in the ass as those pots are not easy to adjust....no wonder my friend suggested I replace them with 10-turn pots.)

They are adjusted by my repair guy. He is extremely knowledgeable with these amplifiers. I am 100% sure he has them set properly.

The ZPA 0.5 has the ability to supply 160v (peak to peak), so the 1600watt at 4ohms is pretty realistic and accurate with proper electrical system and line driver.


That is nuts!


Offline
 Profile  
 
 Post subject: Re: ZPA 0.3 and 0.5 output testing
PostPosted: Fri Aug 30, 2013 6:34 am 

Joined: Sun May 06, 2012 8:01 am
Posts: 1652
I haven't run into many (heck can't even think of any) amplifiers that put out over 1600watts @ 4ohms, these are seriously SQ & very powerful amps.

So your saying you adjust the gain to max prior to clipping? If so then why not just turn the higher channel down a bit to match the lower channel? That way they both be balanced and read the same, then again it might be different with different sine waves.


Offline
 Profile  
 
 Post subject: Re: ZPA 0.3 and 0.5 output testing
PostPosted: Fri Aug 30, 2013 8:04 am 

Joined: Thu Dec 13, 2012 4:24 pm
Posts: 71
Location: PA
I adjusted both channels to slightly under clipping for measurements. In an installation I would adjust each channel the same output and tune from there. Both channels are probably identical in output given the exact same load. In my testing equipment there is a high margin of error and the resistor banks are not 100% identical.


Offline
 Profile  
 
 Post subject: Re: ZPA 0.3 and 0.5 output testing
PostPosted: Mon Oct 21, 2013 5:36 am 
User avatar

Joined: Mon Mar 21, 2011 4:47 am
Posts: 250
Location: Finland
I know the ZPA 0.5 is legendary and all, but lets do the math. It has 50V rail caps so that limits the rail voltage and theoretical maximum power to about 1200W at 4ohms bridged.
I finally found pics of ZPA 0.5 guts without heatsinks and was wowed to find out it has 12 output drivers per channel!



_________________
--
M50, MS275, MPS2500, ZX450, ZPA0.3
Offline
 Profile  
 
 Post subject: Re: ZPA 0.3 and 0.5 output testing
PostPosted: Wed Feb 12, 2014 10:28 am 
User avatar

Joined: Sun Oct 24, 2010 3:12 pm
Posts: 169
Location: Old School, USA
I match my channel gains and still get slightly different output on each channel when I test amps also...it's not you. Cool test, thanks for sharing.



_________________
Old School Car Audio Amp Tests and More:
http://www.youtube.com/BigDWiz

Also see my old school website for tests, reviews and more;
http://www.oldschoolstereo.com
Offline
 Profile  
 
 Post subject: Re: ZPA 0.3 and 0.5 output testing
PostPosted: Wed Feb 12, 2014 10:45 am 

Joined: Thu Dec 13, 2012 4:24 pm
Posts: 71
Location: PA
bigdwiz wrote:
I match my channel gains and still get slightly different output on each channel when I test amps also...it's not you. Cool test, thanks for sharing.


Great.

BTW Shawn does all my restoration :)


Offline
 Profile  
 
Display posts from previous:  Sort by  
 Page 1 of 1 [ 10 posts ] 

All times are UTC - 8 hours


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

cron