How you hook things up for testing?

[DualTriode]

Hello amirm and All,

Sitting on my bench I have an APx555 and an APx1701. I have been building and testing Home Brew tube stuff JFET circuits and speakers.

Recently I purchased a Geshelli DAC and headphone amp and came across your website. I want to get up to speed using the tests that you use.

amirm do have a thread that outlines your procedures and how you hook things up for testing?

Meanwhile I have made a list of the tests that you used testing the Geshelli Archel 2 Pro. Now I am going through the AP500 software manual looking up all the setting and such to do similar tests on the Geshelli Archel 2.5 Pro.

Thanks DT

 

[Blur]

Don't be afraid to reach out toe AP for help. They are really nice and getting you started.

 

[SIY]

Don't be afraid to reach out toe AP for help. They are really nice and getting you started.

This. They have a fantastic library of tech and application notes, and their hotline for tech support will connect you to some superbly knowledgeable engineers. I'm always trying to do something that the instruments aren't really intended to do, and they have been patient and amazingly helpful to me.

Also, Amir has been great about sharing his project files, so that can also help kickstart you.

 

[Blur]

The hardest parts for me when I was involved in some AP testing was first getting the test routines automated and making sense. After that it was getting custom made impedance loads for headphones testing and amp testing. Gotta love VBA coding.

 

[STUDIO51]

The Audio Precision is very intuitive. When I was a college student, I could spend a day alone and perform most measurements. Bench mode and sequence mode are on the top right. First time users may prefer to use sequence mode. The 1701 is equipped with a speaker amplifier and microphone amplifier for measuring headphones and speakers. Activated by selecting Transducer interface on inputs and outputs. In other words, it is not necessary for DAC measurements.

I have a sequence project file on AP.COM that automatically measures the performance of DACs and ADCs. Set the input and output properly and press the start button to run the test automatically.I want to find the URL, but I can't see it Contact AP.

 

[DualTriode]

Hello

What I am attempting to do is match existing procedures to compare apples to apples. How are your connections different?

First off is a new in the box Parasound Zamp v.3, two times 45 Watts Stereo amplifier.



I use one just like on my desktop. The amplifier is cute and little.



See the attached photos of the cords and cables that will be used to test one channel.

Banana plugs

6 feet of 14 AWG speaker zip cord

500 Watt resistor

2, 3way thumb operated UL wire nut sort of things

1, XLR cable

1 BNC cable with 1 BNC to RCA adapter



Thanks DT

 

[Blur]

I'm setting up my own A/B testing station so I can test 2 setups with one pair of headphones. It will be nice to swap back and forth for general amp testing.

 

[DualTriode]

Hello,



This is the right channel of the Parasound Zamp v.3 at 5 watts output into 8Ohms.



THD + N 0.0067%

SINAD 83.3 dB



The power supply has a lot of low level peaks (junk). Typical of a lot of full wave rectified power supplies.



Thanks DT

 

[DualTriode]

Looking around the site I see that asking for the hookup and test procedures is like asking for the recipe for the secret sauce. Oops!



Thanks DT

 

[Blumlein 88]

Looking around the site I see that asking for the hookup and test procedures is like asking for the recipe for the secret sauce. Oops!



Thanks DT

I don't think that is quite the case. You are asking about an AP, and beyond basic test procedures it is a specialized bit of machinery. It is not common. So there aren't a ton of people who can tell you anything helpful. Plus AP has a rep for being very helpful (I don't know haven't had one).

I think in cases where test procedure questions are more general you see plenty of responses. I'd tell you something if I knew, but I have zero experience with the gear you have.

 

[pkane]

Hello,



This is the right channel of the Parasound Zamp v.3 at 5 watts output into 8Ohms.



THD + N 0.0067%

SINAD 83.3 dB



The power supply has a lot of low level peaks (junk). Typical of a lot of full wave rectified power supplies.



Thanks DT

One recommendation is to use the @ sign in front of member names you want to invite into a conversation, like so: @amirm otherwise they may not notice your post.

I don’t have an AP but in trying to measure an amp recently I found that similar low frequency noise is often the product of ground loops or poor ground isolation. You may want to make sure you use balanced interconnects and differential probes. Isolating the AP or the device from common ground may also help.

 

[LTig]

500 Watt resistor
View attachment 44856

Where did you get the 500W load?

 

[DualTriode]

Where did you get the 500W load?

Hello,
Those resistors are used to slow down VFD drives for large HVAC fans and elevators.
see ebay.
Thanks DT

 

[restorer-john]

@DualTriode have to you measured the inductance of that resistor? Some are really low, others not so much.

 

[Doodski]

Where did you get the 500W load?

http://www.arcolresistors.com/

 

[DualTriode]

@restorer-john

Contrary to public opinion, I do not think that it matters. Do not get me started.

The last time I measured speaker impedance the speaker was replaced with a couple of Mills non-inductive resistors. Then the speaker cables were swapped out with zipcord, 12AWG stranded separate wires off a roll and CAT 6 internet cable. It was amazing the different impedance / phase performance of the various cables. A little inductance in the resistor is not going to hurt my feelings.

Okay next time that I get out the speaker impedance tool I will measure the resistor inductance.

Thanks DT

 

[Doodski]

@restorer-john

Contrary to public opinion, I do not think that it matters. Do not get me started.

The last time I measured speaker impedance the speaker was replaced with a couple of Mills non-inductive resistors. Then the speaker cables were swapped out with zipcord, 12AWG stranded separate wires off a roll and CAT 6 internet cable. It was amazing the different impedance / phase performance of the various cables. A little inductance in the resistor is not going to hurt my feelings.

Okay next time that I get out the speaker impedance tool I will measure the resistor inductance.

Thanks DT

The inductance is reactive. Meaning the resistance changes dependent on the frequency. Your multimeter won't measure that.

 

[DualTriode]

The inductance is reactive. Meaning the resistance changes dependent on the frequency. Your multimeter won't measure that.

No mention of multimeter.
APX555 and APx1701 will measure frequency dependent impedance and phase.

 

[DualTriode]

Hello All,

I have been trying a few things. This time I bought form Amazon a couple of female by male XLR cables by Worlds Best Cables with gold plated Neutrik XLR ends and Mogami NEGLEX 2549 Microphone Cable.

I cut the WBC into two equal length pieces and soldered on small #30 Muller alligator clips and hooker it all up to a Crown Com Tech 200 used movie theater amplifier.

The test cables seemed to work fine. The $50.00 amplifier looks like a lot of bang for the buck; SINAD 95 dB’s and THD+N 0.00176 %

See the attached plots.

Thanks DT