BDS PP-131 Spectrum Analyzer

[amirm]

This is a review and detailed measurements of the BDS PP-131 stereo spectrum analyzer. It was kindly drop shipped to me by a member and costs US $359.

I am impressed by the nearly 1000 bars spread nicely across the full audio band. There are a number of modes of operation although I didn't find them that useful other than the default (stereo or mono). Back side impressed me with included power supply and support for XLR balanced input:

The "vibe" I get is that this is a professional piece of equipment. Alas, the actual operation doesn't lend itself to that. There is no calibration or any way of knowing what levels are being displayed. The display clips very early requiring sensitivity to be turned way down. If you turned down the input to allow for higher gain, then you get ghost bars. And main level which constantly changes its upper bars.

Using it as a music visualization is also hard due to above issues and lack of any type of AGC (automatic gain control). Quiet parts of the music show nothing, or random stuff if you turn up the gain. Once you get things dialed up, the display is real-time and quite bright and dynamic. But as a whole, it is rather disappointing.

BDS PP-131 Measurements
I put my Audio precision into its internal loop back mode (input going to output) and then fed the signal to PP-131's input alone:

The result is no impact on the input signal path which is a major plus. Every other VU meter I have tested, has loaded down the input, distorting it. Here, there is no impact if you simply use a Y adapter to split your signal, one going to this box and the other to your amplifier.

If you choose to use the output in the analyzer and save the money on the Y cable, you will be disappointed with the results (I am):

Performance is degraded by both distortion and fair amount noise which I can imagine is coming from the internal processor/display. The gain is also not unity (output should be 4 volts). Lowering the input doesn't help:

There is one bonus: with active path comes the benefit of unbalanced to balanced conversion:

But again, with that noise and distortion penalty.

Frequency response is also rolled off a bit at the top end:

Shame we don't get to better transparency. As such, I wish the was a switch for pass through mode, bypassing the active output buffer.

Conclusions
The PP-131 gets a lot of things right at a bargain price for its feature list. It sort of delivers on some of it if you stay with input mode only, and manually tuning the display sensitivity so that you get data, rather than noise and randomness. The pass through mode is active and unfortunately, is not well implemented. Lots of potential. But not a great story at the end.

I can't recommend the BDS PP-131 Audio Analyzer.
------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

 

[ObjectiveSubjectivist]

Here is clip showing how it looks:

I'm not gonna lie, I don't like it at all.

 

[respice finem]

This is a review and detailed measurements of the BDS PP-131 stereo spectrum analyzer. It was kindly drop shipped to me by a member and costs US $359.
View attachment 535219
I am impressed by the nearly 1000 bars spread nicely across the full audio band. There are a number of modes of operation although I didn't find them that useful other than the default (stereo or mono). Back side impressed me with included power supply and support for XLR balanced input:
View attachment 535220
The "vibe" I get is that this is a professional piece of equipment. Alas, the actual operation doesn't lend itself to that. There is no calibration or any way of knowing what levels are being displayed. The display clips very early requiring sensitivity to be turned way down. If you turned down the input to allow for higher gain, then you get ghost bars. And main level which constantly changes its upper bars.

Using it as a music visualization is also hard due to above issues and lack of any type of AGC (automatic gain control). Quiet parts of the music show nothing, or random stuff if you turn up the gain. Once you get things dialed up, the display is real-time and quite bright and dynamic. But as a whole, it is rather disappointing.

BDS PP-131 Measurements
I put my Audio precision into its internal loop back mode (input going to output) and then fed the signal to PP-131's input alone:
View attachment 535222
The result is no impact on the input signal path which is a major plus. Every other VU meter I have tested, has loaded down the input, distorting it. Here, there is no impact if you simply use a Y adapter to split your signal, one going to this box and the other to your amplifier.

If you choose to use the output in the analyzer and save the money on the Y cable, you will be disappointed with the results (I am):
View attachment 535223
Performance is degraded by both distortion and fair amount noise which I can imagine is coming from the internal processor/display. The gain is also not unity (output should be 4 volts). Lowering the input doesn't help:
View attachment 535224

There is one bonus: with active path comes the benefit of unbalanced to balanced conversion:
View attachment 535225
But again, with that noise and distortion penalty.

Frequency response is also rolled off a bit at the top end:
View attachment 535226

Shame we don't get to better transparency. As such, I wish the was a switch for pass through mode, bypassing the active output buffer.

Conclusions
The PP-131 gets a lot of things right at a bargain price for its feature list. It sort of delivers on some of it if you stay with input mode only, and manually tuning the display sensitivity so that you get data, rather than noise and randomness. The pass through mode is active and unfortunately, is not well implemented. Lots of potential. But not a great story at the end.

I can't recommend the BDS PP-131 Audio Analyzer.
------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

So, to paraphrase youknowwhom - it's a PINO (professional in name only)

 

[Raticosa]

Thanks Amir for this review.
Even if is clear is not a true measuring instrument it would have been very interesting to check for frequency resolution of each single bandpass filter, doing a frequency sweep and checking if, for each center frequency, how many bars will light up (ideally only one if filters are selective enough).
Also amplitude resolution matters, i.e. check how many dB you need to increase the input signal to light up every single dot of each bar.
Pity for bypass mode.

 

[amirm]

Even if is clear is not a true measuring instrument it would have been very interesting to check for frequency resolution of each single bandpass filter, doing a frequency sweep and checking if, for each center frequency, how many bars will light up (ideally only one if filters are selective enough).

I tried to assess this a week ago when I started to test thing. It is just very frustrating to deal with due to noise issues. Sidebands show up easily depending on what level you are using. From what I recall, the bandwidth of each filter is wide enough to encompass two of the sidebands. Again, depending on level.

 

[amirm]

Also amplitude resolution matters, i.e. check how many dB you need to increase the input signal to light up every single dot of each bar.

That was even more frustrating. As soon as you reduce the level from peak, the upper parts of the graph go on and off for any value in between. At times, you can get 2 or 3 LEDs turning on and off! Even when you adjust precisely to a level, the top LED can be dim or full. It kind of sort of works in dB but the foundation is just poor.

 

[pos]

Thanks Amir for this review.
Even if is clear is not a true measuring instrument it would have been very interesting to check for frequency resolution of each single bandpass filter, doing a frequency sweep and checking if, for each center frequency, how many bars will light up (ideally only one if filters are selective enough).
Also amplitude resolution matters, i.e. check how many dB you need to increase the input signal to light up every single dot of each bar.
Pity for bypass mode.

Agreed, the test is focusing on the wrong things.

 

[LTig]

I prefer the RTA display of my Behringer Ultracurve DEQ 2496 by far. It's much more customizable. A few times I used it during mixing of live concerts to check for feedback outside my (age limited) hearing range.

 

[amirm]

Agreed, the test is focusing on the wrong things.

It is not if you read the intro.

 

[OrangeWalrus]

All I want is some cool visualization without sonic artifacts. How hard can it be?

Apparently, very hard.

 

[NTK]

All I want is some cool visualization without sonic artifacts. How hard can it be?

Apparently, very hard.

??? Did you read the review? Use a y-adapter cable to split your signal to the display, and do not use the output.

 

[OrangeWalrus]

??? Did you read the review? Use a y-adapter cable to split your signal to the display, and do not use the output.

Yes, I read. I'm more disappointed in the poor/noisy visual performance. I guess we shouldn't complain too hard about eye candy.

It also has XLR-RCA conversion, but it seems that adds artifacts.

 

[OrangeWalrus]

Using it as a music visualization is also hard due to above issues and lack of any type of AGC (automatic gain control).

On the picture of the back, there appears to be a small hard-to-see toggle labeled "AGC". Did you try that?

 

[aagstn]

I have found memories of my cassette tape days with my deck hooked up to a Technics Spectrum Analyzer. The pretty lights flashing in the background while music played was quite a treat. I eventually wanted to scale my system down to just CD in the early 2000's and sold it and I have always regretted selling it.

 

[Grenadine]

If I wanted to use this device visualization only, can someone recommend a cheap microphone for 1/4" input?

 

[phoenixdogfan]

Obviously, anyone who buys it will use it for eye candy. Reminds me of when I first became interested in the hobby, a company called SAE made things like this to insert into the signal chain to "monitor" your output. Back in the day, affluent audiophiles had their own darkened little salon retreat with a pile of McIntosh blue lit separates complete with VU meters and an SAE spectrum analyzer sitting in their equipment rack--all of it glowing away while the owner sat in his Eames chair with a Baccarat crystal tumbler of single malt scotch listening and taking it all in. Pretty sure an SAE cost a crap ton of money in the early '70's, but that was kind of the point, wasn't it?

Thanks for letting us look under the hood for this piece of retro high tech, Amir.

 

[NTTY]

Great idea as a review, thank you @amirm!

That gives me an idea too, but need to remember where’s the device

 

[Redacted]

The word "pro" is a marketing term.
The packet of seeds for my budgie is "pro food".
I will pay anything to keep my budgie happy.

 

[dtaylo1066]

A nice light show for 360 clams. Can't say I have a use for that type of eye candy. "Not terrible." Some like a good light show. My occasional ocular migraines already provide that, with lots of color. I will spend my 360 on a DAC or something useful.

 

[Yersinia Bestmate]

It baffles me a bit why these kind of gimmicks are nowadays quite frequently reviewed here but then again "to each his own", and it seems some folks really do like the light show and are willing to send their devices to be tested. And yeah, "frequently" can also be interpreted in many ways so do not take this as an offence.