Beogram: Dust covers on or off during when playing

[Giorgione]

Glitch wrote:

It seems like a significant amount of the engineering innovation was a result of overcoming the compromises dictated by the styling. This seems most evident in the speakers made between the 1980’s and 2010’s.

That’s what most people, let alone the audio-files think and gifted the world with such hilarious B&o folks stereotypes personificated by the yuppie neighbours as seen in “National Lampoon’s Christmas Vacation”, ouch! I had Pentas, always thought these pipes and towers were’t really great, the “Sausalitos” were fine, even the BL3 for restricted spaces. But all these powered speakers were lacking something I found again in passive gear.

Giorgione wrote:

I’d like to hear opinions/findings/speculation/test results about these alleged disturbing resonances transmitted via the lid

Have you considered duplicating the pro-jectusa test? This seems like an easy test to setup. You would also have the benefits of testing at the listening levels that you normally use along with your exact equipment location and room acoustics. I don’t put much merit in other people’s “listening tests”. There are too many possible variables that make any results meaningless. Glitch

Easy to setup? How? I don’t think I have the gear to do that – only the ear, ha ha. I don’t pretend my test to be objective but if it sounds better to me either wa it’s still meaningful, to me at least. I also think that most parameters remain the same, whether doing a hearing as well as an instrumental test, the only variable being the lid.

[Glitch]

Giorgione wrote:

Easy to setup? How? I don’t think I have the gear to do that – only the ear, ha ha. I don’t pretend my test to be objective but if it sounds better to me either way it’s still meaningful, to me at least. I also think that most parameters remain the same, whether doing a hearing as well as an instrumental test, the only variable being the lid.

One would already have most of the equipment needed for the test as part of their normal stereo system. Additionally, a multimeter and a phono preamp would be needed to take the reading from the turntable. The phono preamp linearizes and amplifies the signal from the cartridge. The amplified signal should be large enough to measure with the multimeter on the Vac setting. MP3/FLAC test tones would provide the source tones. The only other thing needed is a fair amount of patience to take and record the readings.

I would expect that you will have a difficult, if not impossible, time running a meaningful subjective test. I won’t go into all of the details, but Google something like “A B audio test pitfalls” and you’ll find plenty of info. In addition to the things typically listed, you will also have to deal with echoic memory in the relatively long time it takes to switch lid positions.

I guess in this case, “easy” is a very relative term ;-).

Glitch

 

[Giorgione]

Thanks for the instruction but I neither have an external phono pre-amp nor a multimeter. The physical principle according to the project test seems to clearly indicate that there is an effect and I don’t see any commercial reason faking something here. Maybe a say 4002 will make a difference due to its construction? I will listen to a full record first with closed and then without lid, so there will be a target onject A/B but target group A only – me! Maybe I will repeat the test with other record the upcoming days and eventually stick with whichever versions sounds better to me, and to me only 🙂  I never cared about figures much, only wondering whether somebody in the community came along this question in the past. Seemingly not really.

[Glitch]

It is important to distinguish between “different” and “perceptibly different”. Pretty much any time one makes a change, it will be “different”. This even includes items that were meant to be the same. It was not surprising to me that the three lids positions had different results. What isn’t clear is if any of them are perceptibly different.

What I believe that the test needed to show is a comparison between the noise signal (i.e. the lid/chassis resonance at the cartridge) and the equivalent cartridge signal. The measured relative difference between these two is important. There are many studies that define what a typical human can differentiate. Something like this https://www.ussi.com/acoustical-rules-and-demystifying-decibel.php (this was simply the first hit I noticed on Google).  The good thing about running a test like this is that it takes the monkey out of the loop.

My postulation is that, at typical listening levels and room acoustics, the level differences between the signals, lid up/down/off, are lower than can be perceived. The problem with human judgement tests is that people will “hear” what they want to hear. Sort of like the audio equivalent of “these are not the droids you are looking for”. 😉

I have very good hearing, but I don’t trust my brain to get it right. This is because I’ve tried running a test myself, then getting help from others and running a similar test double blind. The results were different.

Maybe someday I’ll try to run my modified pro-jectusa test and know for sure.

Glitch

• This reply was modified 7 hours, 8 minutes ago by Glitch.

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