Verdant Audio Bambusa MG 1 Speaker Review

[TimVG]

Well, you won't be able to achieve a perfect directivity index (and neither does the Elac with a wave guide), but I don't consider that of prime importance. And it's not true that you can't improve matters by lowering the crossover point. The Excel tweeter's off-axis behavior is very even up to around 2 kHz, and the W18's is better there than higher up. One of my favorite personal designs is the Salk HT-1, which uses the W18 with a proprietary RAAL tweeter crossed a little lower than 2 kHz. If you were listening blind, I bet you wouldn't raise any issues about the perceived radiation pattern, and the last thing I would want to do to the RAAL is slap a wave guide on it.

Again, it's physics. I hope one of you redesigns the crossover and among other things, lower the crossover point. I hope we'll get to see the revised measurements. The 'mess' as described above by a fellow member, in terms of uneven directivity will simply move to a different point. I can't make any comments about a hypothetical blind test. It's pointless. What the science says is when those first lateral reflected sounds match the direct sound in terms of timbre, they are unlikely to be mistaken for coloration - that is what I aim for in a design.

 

[GXAlan]

In my initial work, I made the same cabinets out of MDF, Baltic birch, bamboo, cf reinforced ABS that was 3D printed, fiberglass and carbon fiber, both with Nomex cores.
I used the same drivers and crossovers in each and evaluated them in terms of sound profile and detail listening to the same songs taking careful notes.

In order from best to worst I found CF, Fiberglass, bamboo, Baltic birch, MDF and the CF reinforced plastic cam in dead last.
The difference between MDF, Baltic Birch and Bamboo wasn’t huge and they measured similarly. I used bamboo because I like the look and although pricier, when you take out the need to veneer it, the costs weren’t outrageous and are less than 1/3 of what I pay for a fiberglass cabinet.

the real market for active speakers is that there is no need for additional amplifiers and wires. Takes up a lot less space. That is why I feel like the plate amp is essential.

But that generates the iMac problem. If the amp in an active speaker is as good as the AHB2 but you move to a larger room or advances in driver technology improve, you cannot upgrade just your speaker.

latency can be a problem too unless the whole system is well integrated.

Meridian did active speakers for a long time. Linn. Devialet. Kii. Dynaudio Acoustics.

 

[Dennis Murphy]

Again, it's physics. I hope one of you redesigns the crossover and among other things, lower the crossover point. I hope we'll get to see the revised measurements. The 'mess' as described above by a fellow member, in terms of uneven directivity will simply move to a different point. I can't make any comments about a hypothetical blind test. It's pointless. What the science says is when those first lateral reflected sounds match the direct sound in terms of timbre, they are unlikely to be mistaken for coloration - that is what I aim for in a design.

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.

 

[thewas]

Well, sure, there are limits, and everything in audio is a compromise, but it seems to me there's still a lot you can do just with the crossover and cabinet. I think the main point @Selah Audio was saying is that the primary problem is the crossover.

For example

Here's the Focal Sopra No1. (soundstage network):
View attachment 57212

Q Acoustics Concept 300:
View attachment 57214

Both two-ways with 1 inch tweeters (inverted dome in the focal's case) paired with 6.5-inch woofers and no waveguides(unless you count the slightly shaped trim ring around the concept 300 as a wave guide). Both flat on axis and with directivity smoothness close to many waveguided speakers, while having wider directivity than most waveguided speakers.

You can have a quite smooth horizontal directivity even with a relatively large (mid-)woofer and a tweeter without a waveguide by having a non-steep slopes at the crossover, but you mess-up the vertical directivity, something unfortunately not shown at the Soundstage measurements.

 

[q3cpma]

But that generates the iMac problem. If the amp in an active speaker is as good as the AHB2 but you move to a larger room or advances in driver technology improve, you cannot upgrade just your speaker.

latency can be a problem too unless the whole system is well integrated.

Meridian did active speakers for a long time. Linn. Devialet. Kii. Dynaudio Acoustics.

Bad news, mate: amplifiers, like DACs, aren't audible as long as you don't run into a degenerate case or lack of power leads to clipping. People buy thousand dollars amps not because of sound quality itself, or do you think that a THD of 0.01% (which is bad by amplifier standards) matters when speakers themselves are in the 0.1-0.5% range in the best cases? Especially when the ear isn't very sensitive to harmonic distorsion?
If Genelec or Neumann have no problem with "badly measuring" chipamps like the LM3886 or TDA7292/3, I don't either.

I thing more people here should relax by buying some Crown/Behringer/Yamaha poweramp and counting the money saved not buying a Benchmark or Hypex nCore.


But yeah, I agree with the external and replaceable electronics concept. Sadly, vendors like to keep their electronics proprietary and tied to a specific model.

 

[LTig]

A bit unrelated, isn't Genelec the commercial pioneer for waveguides?

Could be - the 1022A was sold from 1985 to 1990 and looks as having a waveguide for mid and tweeter.

 

[andreasmaaan]

A bit unrelated, isn't Genelec the commercial pioneer for waveguides?

Could be - the 1022A was sold from 1985 to 1990 and looks as having a waveguide for mid and tweeter.

AFAIK, Genelec was one of the earlier commercial adopters. Perhaps they were the first outside of the PA world - I'm not sure.

But anyway, the groundwork for "constant directivity horns" (as they were called then) was Don Keele, who determined the fundamental principles and physics involved in the mid-70s with Electro-Voice.

This is the key technical paper (1975).

EDIT: Peavey was also developing early "constant directivity horns" in the mid-70s. I hope I'm not disrespecting any of their engineers, though, when I say that Keele's work at Electro-Voice was what laid the technical groundwork for future generations of "waveguides".

 

[q3cpma]

Could be - the 1022A was sold from 1985 to 1990 and looks as having a waveguide for mid and tweeter.

There's the 1019A in 1979, apparently.

 

[q3cpma]

AFAIK, Genelec was one of the earlier commercial adopters.

But the groundwork for "constant directivity horns" (as they were called then) was Don Keele, who determined the fundamental principles and physics involved in the mid-70s with Electro-Voice.

This is the key technical paper.

Thanks, interesting paper. But, as always, it's hard to make the difference between horns and waveguides. I am of the opinion that diffraction must be negligible compared to horns to make a difference; otherwise CD horns would be waveguides, indeed.

Some would say that Geddes' 1991 paper "Acoustic Waveguide Theory" is the work that formalized a lot of it.

 

[617]

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.

Dennis- I agree. My experience designing 2 ways with robust tweeters is that a relatively high crossover point produces the smoothest directivity, although this is not without issues. Woofers which play really high are rare.

 

[andreasmaaan]

I am of the opinion that diffraction must be negligible compared to horns to make a difference; otherwise CD horns would be waveguides, indeed.

The problem is, this would rule out all dome tweeter and ribbon "waveguides" like those used by Genelec etc., since Geddes' work applies only to compression drivers.*

But yeh, certainly the term "waveguide" is something Geddes either coined or became most associated with, and it was him who (AFAIK) first focused intensively on throat diffraction at the interface between compression driver and throat.

*EDIT: or theoretically, any driver that produces a planar wave at the throat, but in practice of course this means only compression drivers.

 

[Dennis Murphy]

You can have a quite smooth horizontal directivity even with a relatively large (mid-)woofer and a tweeter without a waveguide by having a non-steep slopes at the crossover, but you mess-up the vertical directivity, something unfortunately not shown at the Soundstage measurements.

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.

 

[akarma]

Dennis- I agree. My experience designing 2 ways with robust tweeters is that a relatively high crossover point produces the smoothest directivity, although this is not without issues. Woofers which play really high are rare.

Lower crossover point =better directivity

 

[Dennis Murphy]

Dennis- I agree. My experience designing 2 ways with robust tweeters is that a relatively high crossover point produces the smoothest directivity, although this is not without issues. Woofers which play really high are rare.

I'm not sure who you're agreeing with. Did you mean to say "relatively low" rather than "relatively high," or are you agreeing with TimVG?
If the latter, how can you get more even directivity at a higher crossover point, where the woofer radiation will be narrower compared with the tweeter than it would be further down?

 

[napilopez]

I'm not sure who you're agreeing with. Did you mean to say "relatively low" rather than "relatively high," or are you agreeing with
napilopez? If the latter, how can you get more even directivity at a higher crossover point, where the woofer radiation will be narrower compared with the tweeter than it would be further down?

I think you meant someone else =]

 

[Lao Lu]

I think ASR testing has clearly shown where the future of 2-way Bookshelf speakers the approximate size of the MG1, M16, R162, JBL 530, DBR-62 will be going:

Build the physical box as solid as practical, 5.25 -6.5 woofers as long throw as possible, tweeters that don't break up or with resonances - and waveguides layout etc to give the best possible DI.

Then throw out the fixed analog crossover. Directly bi-amp each driver. Preceed the external (for future service/upgrade) 'quality AB dual amp' (90 + SINAD, no hiss) with a full DSP pre-processor with fully configurable digital XO, shelving, driver leveling, phase, and multiple/8 PEQ per driver.. Controlled by an Android app on your phone

The 70 yo can shelf raise the treble...Someone else might shelve the bass.. Others PEQ distortion points, resonances, port rasping, etc. One - or everything...

Something like the $449 R162 pair plus $500 for the 4-channel amp and pre-processor... Designed and built as a system...not unlike the Genelec 8431. For $1000.

The 'next generation' of active bookshelf speakers.. No Roon EQ necessary. Nor AutoEQ or miniDSP. It's all included. All configurable.

Are we there yet?

Sounds good....

 

[Dennis Murphy]

I think you meant someone else =]

Ooops Make that TimVG. I've edited my original post.

 

[Lao Lu]

I’d love to see a Fritz Carbon 7 reviewed. I used to have a pair and they sounded really good to me. Fritz is a really nice guy, too.

http://www.fritzspeakers.com/DreamWeaverFritzCarbon7Mk2SpecPage.asp

Martin

Those and the ATC 11s or 19s..listening to Bill Frisell's guitar on the 19s right now and they sound wonderful....I wonder how they would measure...

 

[DeeJay]

Sure. Here are the two (in-room) responses on the same graph:

View attachment 57219

Teal color graph above is at 10 vot, the red one at 2.83. Other than absolute level, there is no difference between them. If I manually move the red graph above, they land on top of each other:

View attachment 57220

Ok, so you meant you would see that and than show to us. I thought so but wasn't sure.
Would that be too much work for you to put all (more) of this graphs in ZIP? Something like extended set of graphs.

 

[617]

I'm not sure who you're agreeing with. Did you mean to say "relatively low" rather than "relatively high," or are you agreeing with TimVG?
If the latter, how can you get more even directivity at a higher crossover point, where the woofer radiation will be narrower compared with the tweeter than it would be further down?

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.