Bagby Mandolin DIY Speaker Review

[Everett T]

As promised, checked up with Meniscus on the design discrepancies for this speaker and here is what I found:

1. The tweeter position was changed by Jeff and so the drawing is correct and so the review speaker is as he intended in that regard. This also means I do not plan to change the speaker I built.
2. The box tuning difference is going to require some additional research and should have a response tomorrow.

In any case, it is a solid performer for the price and, as it is DIY, the port length can be adjusted to taste. Once Amir returns it, will try the longer port and do a nearfield measurement comparison.

Thanks for confirming this. I know the BMRs I built had a few changes and made it a bit more difficult when dealing with the literature.

 

[sarumbear]

That's incredibly loud from a listening position for a speaker.

It is not really. What’s incredible is how vague the mentioned loudness is.

No measurement distance, no frequency range and no signal envelope is defined. Nobody knows if the measurement is made at 1m or 3m. Was a sine wave, pink noise or music used as source? Was the SPL meter averaging or peak reading? Were there any weighing involved?

It’s simply meaninglessness drivel…

However the thread is full of discussions like this with numbers floating around. Come on people, respect science a bit and use units properly when declaring numbers. Let us learn together but please do respect the basic scientific notion, measurement.

Please.

PS. Some try and declare some part of the unit but almost never all of it.

 

[Everett T]

It is not really. What’s incredible is how vague the mentioned loudness is.

No measurement distance, no frequency range and no signal envelope is defined. Nobody nows if the measurement is made at 1m or 3m. Was a sine wave, pink noise or music used as source? Was the SPL meter averaging or peak reading? Were there any weighing involved?

It’s simply meaninglessness drivel…

However the thread is full of discussions like this with numbers floating around. Come on people, respect science a bit and use units properly when declaring numbers. Let us learn together but please do respect the basic scientific notion, measurement.

Please.

PS. Some try and declare some part of the value correct but almost never all.

Agreed, I just took it at listening position and with audio playback. I know, I'm assuming a lot

 

[beagleman]

That's incredibly loud from a listening position for a speaker.

I value my hearing far more than when in my 20s.
Never listen at levels like that for more than a few minutes.

 

[sarumbear]

So, not a mid-field monitor?
I can't speak for others, but I do often measure > 110db peaks at my listening chair. Maybe my "live listening levels" aren't the norm.

Assuming you are about 3m away from the loudspeakers and listening to two speakers playing out stereo music with sustain tones like electric guitars then each speaker is generating around 114dBSPL/m.

110dBSPL at listening position +10dB for 3m distance, -6dB gain for each speaker in a stereo pair = 114dBSPL at 1 m per speaker

That is louder than a chainsaw, which requires sound protective equipment to be worn while operating.

As we have been seeing almost every speaker @amirm measured had unlistenable levels of distortion at 96dB and above, two questions arise:

1- Are you sure your metering is correct?
2- What speaker you are using, which can work at 114dBSPL/m without intolerable distortion? As it can reproduce music order of magnitude louder than anything I see measured at ASR.

 

[richard12511]

Unfortunately the speakers are too large to move and the quad amp and crossover are likely too much of a burden to setup in his test environment. Additionally, I have some concerns about his testing methods when it comes to testing dipole speakers. SL designed all of his speakers with priorities surrounding room interactions. If you read his writings you'll understand that his objective was to make the room part of the music experience instead of fighting to eliminate it as most audiophiles do. Furthermore, while I understand Amir's take on single speaker subjective evaluations, it's not the way SL envisioned his speakers to be evaluated.

I've listened to some of the most highly regarded speakers at CES shows, dealers (including the one I used to work for), folks homes, and even in my own listening room. The LX521.4 system in my non-ideal room sounds so much better than most everything else I have experienced. As I've mentioned in other posts, the JBL 708P was a great sounding speaker, and the third best sounding one I've owned, but in the end, and in my opinion, it's really not in the same league as my LX521.4 system.

Anyone local to Amir in Seattle is welcome to come take a listen (just pm me). The invite also remains open to Amir.

I agree with some of what you say. Everything reviewed by ASR is kinda reviewed against the Harman standard, which I agree is probably inappropriate for a a dipole speaker like this that's designed to use the room.

Still, it's hard to think of a speaker that would be more useful to have complete measurements for. I agree that the review part may not be all that useful, since we have no standard to compare it to. This is why it would be hugely beneficial for science, though. The Harman metric is a great way to assess monopole speakers, but we just don't have anything like that for Dipole or Omni designs. The LX521 is what I would consider an "end game dipole" speaker, so seeing measurements for it will go a long way towards giving us that standard that other dipoles might be judged against.

Since you live in Seattle, maybe you could drop both speakers off at Amir's(most can't do that because it would double shipping costs). Perhaps @amirm could agree to just measure it, and then just give it a "I don't know mailman" panther as he did with the in walls(essentially saying I don't know, since we have no standard to compare to). I would be very interested to hear Amir's impressions of a stereo comparison to his Salon2s, which represent end game monopoles.

Ultimately up to you, and I honestly don't blame you for not wanting to, but I do think it would be hugely beneficial for the science loudspeakers, and especially useful for those of us(like me) who plan to own this speaker some day. As @Francis Vaughan brought up, I'd also be willing to chip in money to help with transportation costs, and I'd bet others would be too. I'd actually be willing to chip in up to $100 .

 

[sarumbear]

Everything reviewed by ASR is kinda reviewed against the Harman standard…

I read about the Harman target FR curve for headphones, but what is the Harman Standard for loudspeaker?

 

[richard12511]

I read about the Harman target FR curve for headphones, but what is the Harman Standard for loudspeaker?

I would say, anechoically flat on axis and LW, with smoothly decreasing early reflections and sound power. I was also kinda referring to evaluating speakers in mono.

 

[maverickronin]

I read about the Harman target FR curve for headphones, but what is the Harman Standard for loudspeaker?

I would say, anechoically flat on axis and LW, with smoothly decreasing early reflections and sound power. I was also kinda referring to evaluating speakers in mono.

Also the Olive score. Some people love a nice simple number.

 

[sarumbear]

I would say, anechoically flat on axis and LW, with smoothly decreasing early reflections and sound power. I was also kinda referring to evaluating speakers in mono.

I don’t know what LW is but I’m sure Tannoy, Wharfedale, Altec Lansing, James Lansing, etc. would object that “a flat frequency response in the audio range” to be named after Harman.

 

[richard12511]

I don’t know what LW is but I’m sure Tannoy, Wharfedale, Altec Lansing, James Lansing, etc. would object that “a flat frequency response in the audio range” to be named after Harman.

LW stands for listening window.

I'm sure there are other manufacturers, too. Harman wasn't the first one to strive for a neutral response. I didn't mean any offense by calling it the "Harman target", it was just an easy and quick way to label it in a way where most people will immediately understand. Harman(and the NRC before them) are (afaik) the ones most known for the semi large sample size, 3 second switch, double blind research showing that such a response is preferred by the majority of listeners. Toole's research was based on researchers that came before them(as you point out), and Toole does a great job of pointing that out in his book.

 

[sarumbear]

I didn't mean any offense by calling it the "Harman target", it was just an easy and quick way to label it in a way where most people will immediately understand. Harman(and the NRC before them) are (afaik) the ones most known for the semi large sample size, 3 second switch, double blind research showing that such a response is preferred by the majority of listeners.

No offence taken by me.

However, I still can’t understand why a flat frequency response was considered to be “preferred” or even needs to be discussed. A loudspeaker is part of the Hi-Fi audio reproduction chain. Isn’t it normal that we expect a flat response throughput the entire operating range of a transducer, DAC, amplifier, etc. is designed for?
If we need a deviation from that flat response we have the equaliser to use.

What am I missing?

 

[Rick Sykora]

No word from Meniscus on box tuning today. Requires some searching of older computer so may take a while...

 

[yourmando]

I agree with some of what you say. Everything reviewed by ASR is kinda reviewed against the Harman standard, which I agree is probably inappropriate for a a dipole speaker like this that's designed to use the room.

Still, it's hard to think of a speaker that would be more useful to have complete measurements for. I agree that the review part may not be all that useful, since we have no standard to compare it to. This is why it would be hugely beneficial for science, though. The Harman metric is a great way to assess monopole speakers, but we just don't have anything like that for Dipole or Omni designs. The LX521 is what I would consider an "end game dipole" speaker, so seeing measurements for it will go a long way towards giving us that standard that other dipoles might be judged against.

Since you live in Seattle, maybe you could drop both speakers off at Amir's(most can't do that because it would double shipping costs). Perhaps @amirm could agree to just measure it, and then just give it a "I don't know mailman" panther as he did with the in walls(essentially saying I don't know, since we have no standard to compare to). I would be very interested to hear Amir's impressions of a stereo comparison to his Salon2s, which represent end game monopoles.

Ultimately up to you, and I honestly don't blame you for not wanting to, but I do think it would be hugely beneficial for the science loudspeakers, and especially useful for those of us(like me) who plan to own this speaker some day. As @Francis Vaughan brought up, I'd also be willing to chip in money to help with transportation costs, and I'd bet others would be too. I'd actually be willing to chip in up to $100 .

+1, I’d be willing to chip in as well to get @mac’s LX521s measured. Even with out the standard time compare to, this exercise would be highly educational. There are plenty of smart people here, including Amir, that can speak to what limitations the NFS may or may not have with dipoles. And his subjective impressions would be interesting too, because he has well trained ears.

 

[richard12511]

I'd entertain having my LX521.4's measured by Amir but a listening session would have to predicate it. I'm not even sure Amir's interested in entertaining the prospect.

Here's a real unprocessed in-room recording using cheap Behringer C2 stereo mics placed at listening position & Scarlet audio interface. YouTube compresses the audio. Play using a set of IEM's or headphones. I use no room EQ because it's not needed.

Sounds great on speakers here! One of those end game speakers I really want to hear someday.

Honestly, I think we have the monopole box speaker measurement to preference correlation decently established. Speakers like this interest me much more.

 

[Rick Sykora]

Back our regularly scheduled review...

No word from Meniscus, so for now will stay with tuning as specified and built.

As for the droop around the crossover point, seems to me like the tweeter has more to contribute than the woofer does. So, modeled the design in VituixCAD. Lowering the crossover frequency while maintaining good driver integration meant tweaks to both filters, but is readily done.

 

[MrHifiTunes]

Back our regularly scheduled review...

No word from Meniscus, so for now will stay with tuning as specified and built.

As for the droop around the crossover point, seemed to me like the tweeter needed to contribute than the woofer could. So, modeled the design in VituixCAD. Lowering the crossover frequency while maintaining good driver integration meant tweaks to both filters, but is readily done.

Which of your builds you like most? What are the strong and weak points of the speakers you made?

 

[Rick Sykora]

Which of your builds you like most? What are the strong and weak points of the speakers you made?

Would take a bit more effort as would want to rate them on multiple attributes. Only one that is a bit harder to build is the Selah Integrity due to the truncated frame for the midrange, but the reward is a the best overall sound of the bunch. Most of them are much smaller than I normally would prefer, so would have to ask whether you plan to use nearfield, far, with or without a subwoofer?

Even though not quite finished, and has the advantage of an active crossover, my preliminary listening suggests that the first Directiva will exceed all the others btw.

 

[alexis]

Wow - I keep looking at it to make sure this is real Mandolin. Is this the "original" NRX driver or is this the Mandolin 2?

I built this 10+ years ago when Jeff initially designed it. Back then, the measurement tool wasn't that user friendly. The OmniMic was just coming out. My measurement is very similar to Amir published. The 100 Hz bass bump is not a problem. So many two way small speakers out there behave that way to give users a perception of more bass. You can hear the difference when you compare that with a flat bass tuning speaker like Philharmonic BMR Monitor. The dip in the 2-4K Hz is real. However, in real listening it wasn't that bad. I'd probably like a bit more BSC. I sold my build to a friend and he is quite happy in his home theater as L and R.

This just brought up so many memories with Jeff B (He passed away). He was really helpful when I'm building it. I think he answered tons of my questions...

 

[Rick Sykora]

Wow - I keep looking at it to make sure this is real Mandolin. Is this the "original" NRX driver or is this the Mandolin 2?

I built this 10+ years ago when Jeff initially designed it. Back then, the measurement tool wasn't that user friendly. The OmniMic was just coming out. My measurement is very similar to Amir published. The 100 Hz bass bump is not a problem. So many two way small speakers out there behave that way to give users a perception of more bass. You can hear the difference when you compare that with a flat bass tuning speaker like Philharmonic BMR Monitor. The dip in the 2-4K Hz is real. However, in real listening it wasn't that bad. I'd probably like a bit more BSC. I sold my build to a friend and he is quite happy in his home theater as L and R.

This just brought up so many memories with Jeff B (He passed away). He was really helpful when I'm building it. I think he answered tons of my questions...

Thanks for sharing! The review unit is a Mandolin 2.