Lx700

[Digi]

Wow, the LX700 looks very interesting, thanks for posting that Chris. To get all of the functionality of LMS it looks like the chassis, signal generator and spectrum analyzer is needed. Will there be a package deal for these three or an upgrade price for those that have LMS? When will it be available for purchase?

Thanks,

Rob

[cstrahm]

Yes we will have a trade-in program. Join the mailing list to get more info. The link is on the main LX700 page.

[werejaguar]

One very good thing about this is, suppose you buy the basic package, LX700 mainframe, the LX711 generator and the LX721 analyzer. You have space for putting 5 more modules, buying them one by one, when you can. For example the power amp and 4 more analyzers (with their microphones), for allowing make pressure field analysis in multiple points. This looks extremely good!

[cstrahm]

Yes there are many possible combinations, that is the advantage of a modular system. You can create the exact kind of analyzer you want, with the exact features you want, and upgrade or reconfigure it in the future. Virtually unlimited.

One of the ideal combinations for production electroacoustic testing is:

- 1X LX711 Generator
- 3X LX721 Analyzer
- 1X LX741 Power Amp
- 1X LX731 I/O Interface

With that system you can measure SPL and true Impedance all at once. Amplitude, distortion, rub&buzz, you name it. And you can also control relays or other production line switching of equipment for each model.

Another modern requirement is polar measurements, where there is often an array of multiple microphones in use. You can have multiple channels of LX721 measuring all the mics at once. Greatly increases the speed of polar data.

Endless possibilities....

[werejaguar]

Chris, when you say "True impedance", are you saying the system will measure both magnitude & phase?, or will do like LMS, measure magnitude, for then calculate phase with min phase transform?

[cstrahm]

Phase is not the issue, the LX711/LX721 are sampled systems so magnitude/phase is automatic. What I was talking about was the method of measuring impedance.

The LX741 has dual Voltage/Current monitor outputs. This means you get both the voltage and current of the load while driving it with a pure voltage source. That is true impedance as measured under actual operating conditions. Think of it like a VI-Box incorporated into the power amp, but even better. With the LX741 you can do SPL and True Impedance all in one shot extremely accurate and very fast and easy. Measuring impedance by the old current source method is very poor. This was all covered in the VI-Box lit and also now in the LX741 lit.

[werejaguar]

So Magnitude & Phase are measured together and automatically.
Yes I noticed the built in VI-BOX :) . But it would be a lo-range VI-BOX because the amp is like small. The original VI-BOX has it's hi-range

So the idea is to have 3 analyzers modules, feeding with.. 1) mic signal for SPL, 2) amp's output voltage, 3) amp's output current?

This way we get SPL and true impedance all at once?

The analyzers get both voltage and current at real time, simultaneosly, so they can measure offset angle between voltage and current, and get true phase?

How much output impedance does the LX741 amp have?, does it use a series shunt like VI-BOX for getting current?

[cstrahm]

>> But it would be a lo-range VI-BOX because the amp is like small.
>> The original VI-BOX has it's hi-range

That's certainly true. Obviously we cannot put a 1000W amp in the LX700. If you need that, then the VI-Box is the way to go. However 90% of the users only care about 1W impedance measurements. But the LX741 can even do 10W/8Ohm measurements. You can easily do tri-level measurements at say 0.1W, 1W, 10W and get great LTD parameters for LEAP. That's what most care about. Comparing the test levels of a 10mA current source, which is 1mW, the LX741 gives you a 10,000:1 power increase over what many have been doing for decades.

Remember the LX741 has DC-200KHz bandwidth. Zero phase shift at low frequencies, and flat response out to very high frequencies. Ideal for precise wide range loudspeaker measurements, from the lowest subwoofers to the highest super tweeters.

We see a lot of user problems with the power amps they choose. You would be surprised how many times we get calls that the mic's response is not flat at high or low frequencies, only to find out the cause is their power amp. Many people ask us for amplifier recommendations. Many amps today are very poor quality.

Add in distortion criteria, and you will find that many people don't have the time or money to buy 10 different amps just to find something that will work, and they can trust. A reference amp that has known capabilities is highly desireable. A further benefit is the fact that you don't have an extra amp to pack around too.

>> The analyzers get both voltage and current at real time, simultaneosly,
>> so they can measure offset angle between voltage and current,
>> and get true phase?

Of course.

>> How much output impedance does the LX741 amp have?
>> does it use a series shunt like VI-BOX for getting current?

No entirely different. It measures current by a shunt, but that is inside the feedback loop of the amp stage and is removed. The output impedance is effectively zero. I think the spec says 10m Ohms just to allow for contact resisance and such.

[werejaguar]

Thanks Chris. Good to see the power amp to be integrated to the laboratory equipment and to have LinearX and Mr Strahm signature. This system will become the standard in every electroacoustic lab

[goldau]

Dear sir
The LX700 can be measure THD in loudspeakers and the amplifier:rolleyes:
What is the method of measuring the Frequency Response and SPL like LMS4.6 or user's MLS

best regards

ZhuYun

[cstrahm]

>> What is the method of measuring the Frequency Response
Miultiple methods: swept sine, lin chirp, log chirp, MLS noise, LCM noise, etc.

[goldau]

the test system is used:
1X LX711 Generator
- 3X LX721 Analyzer
- 1X LX741 Power Amp
- 1X LX731 I/O Interface

I'm want kown the "LX731 I/O Interface" is ness?
how can I buy it in CHINA?,
When can be available for purchase it;)? I'm LMS4.5user

[cstrahm]

Join the mailing list to get more info. The link is on the main LX700 page.