Verdant Audio Bambusa MG 1 Speaker Review

[617]

Lower crossover point =better directivity

The directivity mismatch between differently sized direct radiators will exist at any practical frequency. Cross a 28mm tweeter low enough and its output is extremely wide, while the woofer is naturally very narrow. If you cross it high, the woofer directivity has narrowed, and eventually becomes irregular due to cone break up.

Robust tweeters like this SEAS unit permit designers to make two ways with larger and larger midwoofers, but this is not an approach motivated by the pursuit of smooth off axis response. For me, I would rather have a 40 dollar tweeter and a 80 dollar midrange than any 300 dollar tweeter.

 

[Dennis Murphy]

Dennis, I had a brian fart. If you have a driver of 18cm and one which is 28mm obviously there will be a directivity mistmatch (I feel like an idiot telling this to you of course.) Robust tweeters crossed low and with gentle slope can help the situation, but in my opinion a superior with direct radiators is the use of small midranges. This gives the best result without a waveguide, and in my measurements the smaller the midrange the better. I seem to remember some speakers which even use something like a 35mm dome tweeter as an upper mid crossing to a small tweeter, which is an interesting approach. I agree with you somewhat that the waveguide approach is not the be-all-end-all, but the advantages with 2 ways with 6+" woofers are clear enough. I personally prefer the sound of big waveguides or traditional wide dispersion 3 ways.

I have had luck with big tweeters and 15cm woofers, but the output levels you get there are not impressive, and nobody is making a 3 way with a 15cm woofer. I'm sure you're familiar with Jeff Bagby's continuum - I built a very similar speaker using the sb15 aluminum woofer and the same tweeter.

You may find this chart I prepared a while back interesting; it shows piston directivity at different sizes and frequencies. The curved lines indicate the point at which the piston is down a certain number of db at 40 degrees. I think the stair step lines show a sort of idealized 3 way with only a 4db mismatch between consecutive drivers. I wouldn't claim these crossover points are ideal, but it is interesting to look at.

View attachment 57267

Well, I think we've narrowed our area of disagreement considerably, and maybe we don't disagree at all. I deliberately designed my BMR 3-way to have the widest possible dispersion across the board, and that meant using a special and very small midrange driver, combined with the super thin RAAL ribbon, and a woofer-mid crossover point low enough to avoid beaming from the 7" woofer. And if you check the Audioholics Spinorama measurements, the directivity is quite even. I worked very hard to avoid peaks and dips in the off axis response, although quite frankly that was as much for obtaining pretty pictures as for concern that any such little blips would actually be heard. I have never heard any two-way, with or without a wave guide, that can replicate the sound of the BMR or a speaker like it. So you have no argument with me about the importance of broad dispersion. But we may have a disagreement about whether using a wave guide in a two-way is necessary to get as close to the sound of a 3-way as possible. I've had a whole lotta 2-ways in the house with varying types of wave guides (Geddes, JBL, Klipsch, Buchardt, and various Andrew Jones speakers), and while I admired a couple of them (a JBL monster and a Klipsch monitor), none of them came closer to sounding like a good 3-way than my own Affordable Accuracy 2-way, and most had distinct colorations that were almost certainly due to the wave guides. So, for me, I see no reason to resort to wave guides for 2-ways, and certainly not for 3-ways. I don't want to do anything that will restrict the dispersion of the tweeter even if that means a less-than-perfect directivity match-up in the crossover region.

 

[richard12511]

Well, I think we've narrowed our area of disagreement considerably, and maybe we don't disagree at all. I deliberately designed my BMR 3-way to have the widest possible dispersion across the board, and that meant using a special and very small midrange driver, combined with the super thin RAAL ribbon, and a woofer-mid crossover point low enough to avoid beaming from the 7" woofer. And if you check the Audioholics Spinorama measurements, the directivity is quite even. I worked very hard to avoid peaks and dips in the off axis response, although quite frankly that was as much for obtaining pretty pictures as for concern that any such little blips would actually be heard. I have never heard any two-way, with or without a wave guide, that can replicate the sound of the BMR or a speaker like it. So you have no argument with me about the importance of broad dispersion. But we may have a disagreement about whether using a wave guide in a two-way is necessary to get as close to the sound of a 3-way as possible. I've had a whole lotta 2-ways in the house with varying types of wave guides (Geddes, JBL, Klipsch, Buchardt, and various Andrew Jones speakers), and while I admired a couple of them (a JBL monster and a Klipsch monitor), none of them came closer to sounding like a good 3-way than my own Affordable Accuracy 2-way, and most had distinct colorations that were almost certainly due to the wave guides. So, for me, I see no reason to resort to wave guides for 2-ways, and certainly not for 3-ways. I don't want to do anything that will restrict the dispersion of the tweeter even if that means a less-than-perfect directivity match-up in the crossover region.

Very interesting. Going with this, it would seem that for most speakers, waveguides actually make the loudspeaker worse, not better.

What type loudspeaker do you think waveguides can improve?

 

[TimVG]

I won't continue this debate other than to ask again why you think lowering the crossover point won't help even out directivity. I will--it's physics.

Just to be clear - where you do you assume the Bambusa's drivers cross in the current design, and where would you suggest crossing (lower) to improve its directivity.

 

[Dennis Murphy]

Very interesting. Going with this, it would seem that for most speakers, waveguides actually make the loudspeaker worse, not better.

What type loudspeaker do you think waveguides can improve?

I don't want to go that far. I'm just saying that wave guides aren't essential to produce good sound in 2-ways, and that wave guides are tricky to implement. Above all, don't dismiss a speaker out of hand just because it doesn't use a wave guide. With or without them, it all comes down to solid engineering and knowing what live music really sounds like.

 

[Dennis Murphy]

Just to be clear - where you do you assume the Bambusa's drivers cross in the current design, and where would you suggest crossing (lower) to improve its directivity.

Judging from the vertical off-axis plots, it looks like the crossover is already at or below 2 kHz. But don't know the slopes, or what attempt was made to get the drivers to sum flat. If the crossover had been optimized correctly, without an on-axis sag or elevated highs, the speaker would probably sound excellent even if the DI had a bump or grind or two. There are too many successful implementations of these drivers to think otherwise.

 

[TimVG]

Judging from the vertical off-axis plots, it looks like the crossover is already at or below 2 kHz. But don't know the slopes, or what attempt was made to get the drivers to sum flat. If the crossover had been optimized correctly, without an on-axis sag or elevated highs, the speaker would probably sound excellent even if the DI had a bump or grind or two. There are too many successful implementations of these drivers to think otherwise.

I believe you are correct, and I don't believe with this in mind, lowering the crossover further would bring any useful benefit (which is what I was getting at). I completely agree that if the direct sound will be optimised, this speaker will sound better. A -slight- depression in the on-axis, where the off-axis bloom is widest could also perhaps work in its favor.

 

[thewas]

Just about any conventional speaker will have messed up vertical directivity. But I don't think we're at the point where we know whether that's important or not. Soundstage does sneak a bit of vertical information in their listening window plot, which includes the response 15 degrees up and down from the listening axis. I have to assume that the people who designed the NRC protocol thought detailed vertical off-axis plots weren't very important, or that they would be difficult to evaluate.

Its a big difference if you have a vertical dip at 15° of-axis (which is often a listeners height) of 3 or more than 6 dB as it often happens at designs with shallow slopes like for example current B&Ws.

Look for example at the vertical directivtiy of the D&D 8c despite its large mid driver and distance to the tweeter, thanks to its waveguide and steep crossover its very smooth

(Source: https://www.stereophile.com/content/dutch-dutch-8c-active-loudspeaker-system-measurements)

versus the one of the B&W 805 D3

which thanks to its shallow slopes still manages a smooth horizontal directivity

(Source: https://www.stereophile.com/content/bowers-wilkins-805-d3-loudspeaker-measurements)

Also the here measured Neumann KH80 shows a very smooth vertical directivity for a non-coaxial design

Now about the people of the NRC, their measurements are based on the work when Toole was there. Harman never considered much the vertical directivity, maybe also due to the fact they never had a great coaxial product and the audibility can be discussed, but here we talk about the technical/theoretical optimum and IMHO its hypocritical to ignore this significant factor just as most products don't manage it very well, especially in current times were enough products are there to show that it can be done well.

 

[tuga]

The directivity mismatch between differently sized direct radiators will exist at any practical frequency. Cross a 28mm tweeter low enough and its output is extremely wide, while the woofer is naturally very narrow. If you cross it high, the woofer directivity has narrowed, and eventually becomes irregular due to cone break up.

Robust tweeters like this SEAS unit permit designers to make two ways with larger and larger midwoofers, but this is not an approach motivated by the pursuit of smooth off axis response. For me, I would rather have a 40 dollar tweeter and a 80 dollar midrange than any 300 dollar tweeter.

I know that science says I don't prefer it, but if I'm listening on-axis nearish-field (~2m) I'll take the better tweeter with flat on-axis response and larger woofer with presence-dip off-axis over a "compromised" tweeter and smaller woofer with a smoother off-axis response, even if the side-walls aren't treated.

 

[thewas]

I know that science says I don't prefer it, but if I'm listening on-axis nearish-field (~2m) I'll take the better tweeter with flat on-axis response and larger woofer with presence-dip off-axis over a "compromised" tweeter and smaller woofer with a smoother off-axis response, even if the side-walls aren't treated.

But why chose between 2 obvious compromises when there exists a better 3rd solution which doesn't necessarily must cost much more?

 

[tuga]

But why chose between 2 obvious compromises when there exists a better 3rd solution which doesn't necessarily must cost much more?

I agree, but I was commenting on that particular A or B choice.

 

[verdantaudio]

The question is "o they have enough sex-appeal" to play the big league.

The website put me off, it's too amateur in terms of navigation and not sufficently "lifestyle-pretty" either.
And the speakers don't look particularly expensive nor stylish nor high-tech nor vintage.

Regarding the web-site, I am going to go through and do a redesign to make it more in-line with our Art Audio US site which is easier to navigate. I haven’t had the time.

to bring it up to a higher standard, it costs money. Particularly photo shoots. This is a self funded venture and I did not sell another business to fund it.

 

[verdantaudio]

I have added the Verdant Audio Bambusa MG 1 to Loudspeaker Explorer where it can be compared to other speakers.

Looks like the speaker has a significantly better response when listened to slightly off-axis - I wouldn't toe these in:

View attachment 57059

These angles in particular might be a bit better:

View attachment 57061

. At CAF, we had these displayed side by side with our Blackthorn and Nightshade products and you are right. They were toed slightly but where we had our other product toed to a point where the sweet spot was the mid point between the two rows of seats, with these the sweet spot would have been well behind the 2nd row, through the wall, in the bathroom.

 

[617]

But why chose between 2 obvious compromises when there exists a better 3rd solution which doesn't necessarily must cost much more?

The science says that the closer you are, the less this matters, since the proportion of reverberant energy you hear is lower the closer you are to the speakers... eventually they become headphone

 

[617]

I don't want to go that far. I'm just saying that wave guides aren't essential to produce good sound in 2-ways, and that wave guides are tricky to implement. Above all, don't dismiss a speaker out of hand just because it doesn't use a wave guide. With or without them, it all comes down to solid engineering and knowing what live music really sounds like.

The obvious comment here is - why is a flat baffle, effectively a 180 degree waveguide with edge diffraction superior to restricted coverage? Have you ever designed a speaker with minimal baffle around the tweeter, for example?

For the most part I agree with you but the gentle shallow waveguides such as those used by revel and many diyers seem to be a great compromise between the uncolored sound of direct radiators and the performance of more hornish configurations. Even the SS 9900 has a waveguide you could argue.

On a separate note have you heard the big wavecor waveguide unit?

 

[ctrl]

The directivity mismatch between differently sized direct radiators will exist at any practical frequency. Cross a 28mm tweeter low enough and its output is extremely wide, while the woofer is naturally very narrow. If you cross it high, the woofer directivity has narrowed, and eventually becomes irregular due to cone break up.

Would agree in principle, but one has the possibility to make the overall radiation relatively even.
For example, the baffle around the tweeter could be made a bit narrower so that the radiation at lower frequencies is somewhat wider .
At the height of the tweeter, the baffle is reduced in width, so that the edge diffraction moves to higher frequencies and the tweeter radiates less wide in the 2-4kHz range.
This allows a more even radiation at the transition between woofer and tweeter.

Even when using a 0.75'' tweeter with a 6.5'' bass driver the horizontal radiation is more or less even. But this does not work with an "standard" baffle design. On the other hand, the baffle with a horizontal constriction around the tweeter no longer appears so elegant.

Bambusa MG 1

0.75'' tweeter with a 6.5'' woofer and "special baffle" (baffle is reduced in width at the height of the tweeter)

The too much "sound power" in the range 3-6kHz has to be compensated with a slight dip on axis.

The vertical radiation pattern is similar, except that in my example the crossover frequency is deliberately chosen higher in order to extract "sound power" in the area of the ear canal resonance (at about 2.7kHz).

Bambusa MG 1

0.75'' tweeter with a 6.5'' woofer and "special baffle" (baffle is reduced in width at the height of the tweeter)

Even simple 2-way loudspeakers can be designed in such a way that the radiation is certainly not optimal, but still quite even.

 

[617]

Would agree in principle, but one has the possibility to make the overall radiation relatively even.
For example, the baffle around the tweeter could be made a bit narrower so that the radiation at lower frequencies is somewhat wider.

Even when using a 0.75'' tweeter with a 6.5'' bass driver the horizontal radiation is more or less even. But this does not work with an "standard" baffle design. On the other hand, the baffle with a horizontal constriction around the tweeter no longer appears so elegant.

Bambusa MG 1
View attachment 57304

0.75'' tweeter with a 6.5'' woofer and "special baffle"
View attachment 57305
The too much "sound power" in the range 3-6kHz has to be compensated with a slight dip on axis.

The vertical radiation pattern is similar, except that in my example the crossover frequency is deliberately chosen higher in order to extract "sound power" in the area of the ear canal resonance (at about 2.7kHz).

Bambusa MG 1
View attachment 57307

0.75'' tweeter with a 6.5'' woofer and "special baffle"
View attachment 57308

Even simple 2-way loudspeakers can be designed in such a way that the radiation is certainly not optimal, but still quite even.

I'm confused here - what is the 'special' baffle you are referring to here?

 

[HammerSandwich]

Look for example at the vertical directivtiy of the D&D 8c despite its large mid driver and distance to the tweeter, thanks to its waveguide and steep crossover its very smooth

Having the crossover at only 1.2kHz helps as well.

Interesting to compare the 8C with the Kii (Stereophile measurements), because the Kii's waveguide & mid are roughly half the diameter. You can see that the 8C has a narrower horizontal pattern, but polar smoothness appears similar in both horizontal & vertical. Although the vertical plots cover only a narrow window, we can find worse examples.

 

[Robbo99999]

I've seen a few posts here in reference to wave guides and directivity and the importance of how that is integrated into the woofer's interaction with the tweeter...if I understand this broadly (I'm a bit of a newbie). I just wanted to ask if EQ'ing a speaker close to or over the frequencies of a speakers crossover could cause unwanted effects even if the EQ was accurately following the curve of your choice (e.g. Harman)? I only say this because I've recently bought JBL 308's and have EQ'd them to my room using UMIK-1 and miniDSP (and Equaliser APO in some implementations), and I've got it matching the Harman curve pretty good, but I feel it's removed some of the spatial feel (even though it sounds more balanced)....these speakers almost used to sound like surround sound when watching movies before I EQ'd them (2 channel system I have) with certain sound effects even sounding like they were coming from behind me for instance. I ask because my intuition tells me it's related somehow to waveguides and 'tuning' which has been referred to in this thread...ie this manufacturer had great parts but didn't put them together too well.....have I kinda destroyed some aspects of my speakers tuning by EQ'ing them? I don't want to derail this thread, but I couldn't help notice some kind of relevance to what has been discussed in this thread re. 'tuning' and I wanted to just ask this quick question.

 

[ctrl]

I'm confused here - what is the 'special' baffle you are referring to here?

Sorry for that!
At the height of the tweeter, the baffle is reduced in width, which causes the edge diffraction to migrate to higher frequencies and the tweeter radiates less widely in the 2-4kHz range.
This allows a more even radiation at the transition between woofer and tweeter.