Bagby Mandolin DIY Speaker Review

[gopher]

Thanks for reviewing these. I have always had great respect for Jeff Bagby and his designs, although I have yet to actually hear one. His designs have had incredible success and seem to have almost universal acceptance, so this is the first review with detailed and objective measurements I've seen which seem to give a slightly different perspective. I'm still a novice speaker-designer having only built kits and subwoofers, but I do still believe that DIY speaker kits are probably still the best way to get high performance at a reasonable cost.

*** EDIT - Started new thread about the Joseph Crowe model 1159 here ***

I had been looking at both of JB's Mandolin and Piccolo kits at Meniscus Audio, which I think really only differ in the size of the midwoofer. But then I recently stumbled upon a fellow Canadian named Joseph Crowe who does fascinating and beautiful work on his waveguide and horn designs. He offers what he calls the "Model #1159 Stand-Mount Series Monitor" which uses exactly the same 5" SB Acoustics woofer and tweeter as Jeff Bagby's slightly smaller Piccolo kit, but offers a gorgeous CNC-machined, solid walnut baffle with perfect time alignment of the woofer and tweeter for what I think is pretty reasonable price. The pic below is of Joseph's own build, not mine:

More info: https://josephcrowe.com/collections/see-all-no-1159-products/products/speaker-no-1159-baffle-only

 

[DanTheMan]

I just showed that picture to my wife and her first comment was on the plant behind the speaker.... anyway, that whole stereo looks beautiful!

 

[sarumbear]

I recently stumbled upon a fellow Canadian named Joseph Crowe who does fascinating and beautiful work on his waveguide and horn designs. He offers what he calls the "Model #1159 Stand-Mount Series Monitor" which uses exactly the same SB Acoustics woofer and tweeter as JB's Piccolo kit, but offers a gorgeous CNC-machined, solid walnut baffle with perfect time alignment of the woofer and tweeter for what I think is pretty reasonable price. Joseph even offers a full-flatpack for this design too. His blog post about the design indicates that a very simple first-order crossover is all that is necessary here. Has anyone heard or tried these? Any of the DIY speaker guys here care to comment?

View attachment 127455

More info: https://josephcrowe.com/collections/see-all-no-1159-products/products/speaker-no-1159-baffle-only

Hence diffraction free enclosures is possible for the DIY market.

 

[ROOSKIE]

Thanks for reviewing these. I have always had great respect for Jeff Bagby and his designs, although I have yet to actually hear one. His designs have had incredible success and seem to have almost universal acceptance, so this is the first review with detailed and objective measurements I've seen which seem to give a slightly different perspective. I'm still a novice speaker-designer having only built kits and subwoofers, but I do still believe that DIY speaker kits are probably still the best way to get high performance at a reasonable cost.

I had been looking at both of JB's Mandolin and Piccolo kits at Meniscus Audio, which I think really only differ in the size of the midwoofer. But then I recently stumbled upon a fellow Canadian named Joseph Crowe who does fascinating and beautiful work on his waveguide and horn designs. He offers what he calls the "Model #1159 Stand-Mount Series Monitor" which uses exactly the same SB Acoustics woofer and tweeter as JB's Piccolo kit, but offers a gorgeous CNC-machined, solid walnut baffle with perfect time alignment of the woofer and tweeter for what I think is pretty reasonable price. Joseph even offers a full-flatpack for this design too. His blog post about the design indicates that a very simple first-order crossover is all that is necessary here. Has anyone heard or tried these? Any of the DIY speaker guys here care to comment?

View attachment 127455

More info: https://josephcrowe.com/collections/see-all-no-1159-products/products/speaker-no-1159-baffle-only

I have checked his site from time to time and he has a few youtube videos as well.
Really beautiful work and seems to know his stuff.

He says he is working on a Purifi based floor stand speaker with the same horn/tweeter and dimple dome.

By the way in the 1159, he is using the 5" Sb Acoustics woofer not the 6.5". Still very similar in terms asking "what can be done with the same drivers and yet very different designs".

 

[Everett T]

An 83db sensitive speaker that produces moderate distortion at 96db. I suppose this speaker might appeal to someone.

I'd assume that above 90db no one is considering this speaker. As a 2ch, midfield speaker it behaves as expected.

 

[ROOSKIE]

An 83db sensitive speaker that produces moderate distortion at 96db. I suppose this speaker might appeal to someone.

This is not really far from just about every smaller 2-way in terms of distortion. Sensitivity of 83 db is more common that not. Yah, 85/86 is the norm with maybe 87/88/89 for a few 2 ways.
Looks like the speaker has 6db or so of BSC built in (which is why Amir was confused about the nearfield drop off mesurement)
These are for being pulled out well away from walls and still have very full bass. (true "audiophile" style)

Plus lets be honest.
Not very many people listen @ 96db. Peaks are one thing, 96db constant is very loud and very different.
I think most people would be shocked to realize how loud 96db testing sweeps are and how loud other testing signals are.
Most people would be best to look at the 86db distortion profiles and assume that is what they will see/hear.

I do listen loudly sometimes, and so I can understand why the testing for 96db is a good thing. Still it is a high value SPL.

 

[Nathan Raymond]

This is a review and technical measurements of the (late) Jeff Bagby Mandolin DIY kit as built by our member, @Rick Sykora. Looks like the drivers and crossover for a pair cost US $316.42. Rick will have to advise as to the rest of the cost.

As usual, Rick has built this speaker as a tank, weighing far more than commercial speakers its size:

View attachment 127295

As expected, there is a port in the back:

View attachment 127296

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

I performed over 1400 measurement which resulted in error rate of around 1%.

Testing temperature was around 65 degrees F.

Reference axis for measurements was the center of the tweeter (by eye).

Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.

Bagby Mandolin Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:
View attachment 127297

On-axis response is less even than I like. We have some peaking around 100 Hz but then a broad dip up to 700 Hz. There is another dip around crossover region of 3 kHz. Tweeter is beaming due to lack of waveguide as you will see later.

Efficiency is low averaging around 83 dB (by eye) so you need a lot of power to drive this speaker.

Port resonance is not an issue but woofer seems to be running out of steam before tweeter takes over:


View attachment 127298

Early window reflections show the results of tweeter narrowing:
View attachment 127301

And here is the combined, predicted response:

View attachment 127302

Horizontal beam width shows the uneven directivity of the woofer and tweeter:

View attachment 127303

I have shown a secondary upward arrow to show the physics of beam width reducing in size as frequencies get smaller (relative to size of the tweeter). Same is seen in contour graph:

View attachment 127304

Vertical response shows more degrees of freedom than some other 2-way speakers:
View attachment 127305

Distortion is good at 86 dBSPL:

View attachment 127306

View attachment 127307

Finally, impedance at nearly 7 ohm should be easy for any amp to drive (that has the power this speaker needs):

View attachment 127308

Speaker Listening Tests
Garden season has started and with me spending a lot more time outside during fruit tree blossoming, my ears are fully plugged today. I did a quick listen and could hear the effect of bass boost around 100 Hz since I also have a room mode there. Lowering that peaked not only helped with a bit of boominess but also resulted in more clarity upstream indicating lowering of distortion. Above bass my ears were to clogged to asses anything so not much else to report.

Conclusions
I don't have any since I could not complete my subjective evaluation. You all can post what you think.

------------
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

 

[Nathan Raymond]

...to clogged to asses...

I believe you meant to write "too clogged to assess".

 

[Rick Sykora]

Thanks for reviewing these. I have always had great respect for Jeff Bagby and his designs, although I have yet to actually hear one. His designs have had incredible success and seem to have almost universal acceptance, so this is the first review with detailed and objective measurements I've seen which seem to give a slightly different perspective. I'm still a novice speaker-designer having only built kits and subwoofers, but I do still believe that DIY speaker kits are probably still the best way to get high performance at a reasonable cost.

I had been looking at both of JB's Mandolin and Piccolo kits at Meniscus Audio, which I think really only differ in the size of the midwoofer. But then I recently stumbled upon a fellow Canadian named Joseph Crowe who does fascinating and beautiful work on his waveguide and horn designs. He offers what he calls the "Model #1159 Stand-Mount Series Monitor" which uses exactly the same SB Acoustics woofer and tweeter as JB's Piccolo kit, but offers a gorgeous CNC-machined, solid walnut baffle with perfect time alignment of the woofer and tweeter for what I think is pretty reasonable price. Joseph even offers a full-flatpack for this design too. His blog post about the design indicates that a very simple first-order crossover is all that is necessary here. Has anyone heard or tried these? Any of the DIY speaker guys here care to comment?

View attachment 127455

More info: https://josephcrowe.com/collections/see-all-no-1159-products/products/speaker-no-1159-baffle-only

Welcome to ASR!

While clearly some nice woodworking, any further discussion of these clearly belongs on a new thread. Feel free to start one and I (and anyone else who is willing), will help evaluate.

 

[ROOSKIE]

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.

Mid field is a fairly broadly used term.
I didn't say anything about them not being appropriate for any particular listening distance.
I do think they were designed for less wall support, pulled out and well away.
No 110db peaks are not common. I understand a few folks will want that however I personally don't know 1 single person who listens that way.
My max is about 90db with 100ish db peaks and while wonderfully fun is way louder than most people. Sitting 10-11 feet away, speakers 9 feet apart in a medium listening room. This is right around the play-back level where 2 ways with 6" drivers start to really need to be high passed to subs in order to play all things cleanly.
Obviously for some folks 110db is factor but I really think that the typical cat/dog/fool or whoever is unlikely to hit those levels ever, nit even showing off for friends. (again just speaking about the typical audio oriented persons threshold)
Plus that HD test at 96db is a true 96db sweep, not a summmed 96db pink noise test. It is much louder so the HD test is really likely closer to distortion levels with peaking not with a c-weighted average sort of spl.
IMD would be a better test but is really fairly complicated to run.

 

[tktran303]

Looking closer at the distortion measurement @96dB

first off, above 300Hz it is still very low- the 2nd harmonic is ~45 down and the 3rd harmonic is ~55dB down. Higher order harmonics are likely ~65dB or more down, and thus likely below the noise floor of the room.

So from a harmonic distortion view, as a midrange only, is very good showing
what’s curious is that things fall apart below that, and much faster below 100Hz.
Is it average for a 6.5” driver? Worse than average?
Let’s take a look at another 6.5” two way-

https://www.audiosciencereview.com/...s/jbl-306p-mk-ii-review-studio-monitor.18505/

At 96dB AND 86dB, it visually appears like a mess!

but lots of research into THD has shown that it alone doesn’t correlate with sound quality-

how does it sound to the ear? @Zvu @hardisj

 

[ta240]

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.

Edit: Link added.

Based on your equipment list it would appear you don't use sub $500 small speakers either.

I would think this is a classic case of making sure ones equipment matches their needs.

A person that would build and use these speakers would likely be terribly disappointed in the speakers you use if they put them in the same place in the room

 

[restorer-john]

You are mistaken. Mass producing angled edged enclosure panels is no different to straight cornered ones.

I know from experience.

Every single manufacturing process/step costs money. Each machine has a cost per hour. Straight cuts have minimal material wastage (more panels per board) are by far the most efficient and can be done at the lowest cost.

I also say this from experience.

 

[Everett T]

Mid field is a fairly broadly used term.
I didn't say anything about them not being appropriate for any particular listening distance.
I do think they were designed for less wall support, pulled out and well away.
No 110db peaks are not common. I understand a few folks will want that however I personally don't know 1 single person who listens that way.
My max is about 90db with 100ish db peaks and while wonderfully fun is way louder than most people. Sitting 10-11 feet away, speakers 9 feet apart in a medium listening room. This is right around the play-back level where 2 ways with 6" drivers start to really need to be high passed to subs in order to play all things cleanly.
Obviously for some folks 110db is factor but I really think that the typical cat/dog/fool or whoever is unlikely to hit those levels ever, nit even showing off for friends. (again just speaking about the typical audio oriented persons threshold)
Plus that HD test at 96db is a true 96db sweep, not a summmed 96db pink noise test. It is much louder so the HD test is really likely closer to distortion levels with peaking not with a c-weighted average sort of spl.
IMD would be a better test but is really fairly complicated to run.

I think your thinking is inline with most listeners.

 

[richard12511]

Thanks for reviewing these. I have always had great respect for Jeff Bagby and his designs, although I have yet to actually hear one. His designs have had incredible success and seem to have almost universal acceptance, so this is the first review with detailed and objective measurements I've seen which seem to give a slightly different perspective. I'm still a novice speaker-designer having only built kits and subwoofers, but I do still believe that DIY speaker kits are probably still the best way to get high performance at a reasonable cost.

I had been looking at both of JB's Mandolin and Piccolo kits at Meniscus Audio, which I think really only differ in the size of the midwoofer. But then I recently stumbled upon a fellow Canadian named Joseph Crowe who does fascinating and beautiful work on his waveguide and horn designs. He offers what he calls the "Model #1159 Stand-Mount Series Monitor" which uses exactly the same SB Acoustics woofer and tweeter as JB's Piccolo kit, but offers a gorgeous CNC-machined, solid walnut baffle with perfect time alignment of the woofer and tweeter for what I think is pretty reasonable price. Joseph even offers a full-flatpack for this design too. His blog post about the design indicates that a very simple first-order crossover is all that is necessary here. Has anyone heard or tried these? Any of the DIY speaker guys here care to comment?

View attachment 127455

More info: https://josephcrowe.com/collections/see-all-no-1159-products/products/speaker-no-1159-baffle-only

That's a pretty speaker! Also, Joseph is a member here at ASR. @Joseph Crowe. I really enjoy his videos, and I have little to no interest in DIY.

 

[richard12511]

I do listen loudly sometimes, and so I can understand why the testing for 96db is a good thing. Still it is a high value SPL.

My serious listening is usually mid to high 80s, c weighted. For someone like me, I'm guessing that means the 96dB sweep is pretty relevant for average listening? I wonder what the average bass and low mid levels are for these volumes. Obviously the 96dB is not relevant for treble, at least not for my average level.

 

[ROOSKIE]

My serious listening is usually mid to high 80s, c weighted. For someone like me, I'm guessing that means the 96dB sweep is pretty relevant for average listening? I wonder what the average bass and low mid levels are for these volumes. Obviously the 96dB is not relevant for treble, at least not for my average level.

IMHO as far as correlation between HD values acheived with the sweep at 86db during the sweep and playback SPL using a c-weighted meter mid 85 playback is roughly indicated by the 86db HD test.
Look at the levels of the frequency spectrum in REW ot another app that shows the full band broken down.
Using 2 speakers with room gain is a factor as well. Even bass which is where a lot is demanded of the system is getting real reinforcement from the room.

 

[tktran303]

My serious listening is usually mid to high 80s, c weighted. For someone like me, I'm guessing that means the 96dB sweep is pretty relevant for average listening? I wonder what the average bass and low mid levels are for these volumes. Obviously the 96dB is not relevant for treble, at least not for my average level.

I think there’s a pretty easy (and quick/dirty) test to get a real feel for that.

Just set your system volume for whatever you generally like to listen at.

then unplug all but one speaker.

then go sit at 1m to that speaker, then play this sweep

https://www.audiocheck.net/testtones_sinesweep20-20k.php

Using an SPL meter (or equivalent eg. iPhone with MobileTools or favourite SPL app- these will get you in the ballpark +/-1dB)

wind up (or down) your main volume control until you read 96dB-

You may be surprised that 96dB @1m from a single speaker is quite loud- near the limits of what you can tolerate.

 

[Everett T]

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.

Edit: Link added.

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

 

[ROOSKIE]

Not currently, but if I did it would be LXmini.

I have that on my list as well.