First speaker build : Bagby Continuum questions

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Hey guys!

First post for me here. I've been scouting and reading the forum for long but I'm glad to get into the mix of posting! I'm an international grad student in Atlanta, love listening to high-quality audio gear, and am looking to get into DIY audio.

Long post ahead :

Music taste : Jazz, blues, old rock, acoustic instruments, vocals, folk


I'm relatively new to DIY speakers, and was going to start on my first build project this summer, and from reading for a few days I've (kind of) decided to go ahead to do a Jeff Bagby designed speaker. I am,however, extremely confused as I am on a pretty tight budget (student life) and will be committing to these speakers at least for a few years, so I really need to justify the budget I'll be investing into the project, I was thinking a maximum of 1k-1.1k including speaker kit+cabinets, amplifier, cables, subwoofer if required etc.

While initially I was very attracted towards the Kairos, my budget started pulling me more towards the Continuums. I've only heard fantastic things about them, owing to a sweet midrange and lush highs, and it sounds like the speaker to have. I had some questions regarding filling into the bass category though.

I am not a basshead, neither do I care for maximum extension. I prefer what is there to be clean, tight and not overdone. I'm happy with a speaker going down to 35Hz within the budget if it allows for better SQ than going down to 20Hz

- As per integration of bass to lower mids, will the continuum + subwoofer mix be far different from the 3-way design available?
The 3-way from rough calculation would come out to about $800 for the project unless I'm mistaken. Also would be the slight difficulty in the build with increased components. I'm happy to spend about 200-250$ on a sealed subwoofer to keep costs at around 600$, so I can have 300-400 for the amplifier.

Also, because of the 3-way integration, I'm assuming I would need a better amplifier to push the speakers ( as opposed to a smaller amp and active subwoofer). Would the 3-way significantly push my amplifier budget?

- I've heard of the TL design by Maynardg, but I haven't heard much about the sound signature changes. How different will it be vs continuum with sub?

- Will the continuum + subwoofer be subjectively compareable in sound to the Kairos standalone? I know they were designed with different objectives, but just in terms of reproducing great listenable sound without the time alignment, will it do as well?

- Does the subwoofer addition allow the continuums to be pushed to a slightly higher SPL? I've heard they are limited in that area. But I have no reference as to what "reasonable levels" are or what "loud" is. These will be played in a smallish room(10x10x10) maybe, and not too far away from the wall. I usually prefer medium volume, but I would like to crank it up a bit for a few songs or maybe once or twice for movies.

A few questions about cabinet construction :
I will have access to a shop with several tools, CNC etc for the entireity of the project, however it will be my first woodworking project. I was fascinated with the idea of different non-rectangular cabinets, and am willing to experiment as long as it doesn't interfere with the SQ.

- I saw some translam cabinets built and fell in love with the concept. With appropriate inner bracing, keeping baffle dimensions the same and volume the same will it sound the same? Can I flush mount the baffle which will be easier in this case?

- If someone did do a flatpack of the design, after I purchase the kit, would someone be legally and willingly able to share the design files with me?


And a few questions regarding amplifiers :
My only experience with amps so far have been a Marantz AVR(lower end) and an SMSL 30W amp. Marantz was pretty sweet sounding to me, but that could have been the Dali speakers they were running. I find it very hard to distinguish between whether a sound feature was because of the amplifier or because of the speaker.

If I was in the market for an amplifier to run the Continuums, budget (200-400 maximum) , and was happy to look at used systems, what should I watch out for? I've heard classic NADs do a good job, old Yamahas do as well but for newer age models I've heard the Music Hall a15.2 , Rega Brio etc are a step above. Are they significantly different in driving the Continuums? In anyones experience, which budget amplifier did they find a great fit with these speakers?

Lastly, does someone in the Atlanta area have built JB designs that I could possibly audition? It would really help affix my decision. If not, is it possible to compare the sound signature of the continuums to something available in the commercial market, so I can audition those instead? In my experience, I have loved Dali Zensors,
Magneplanars, and B&W D802 sound. I definitely was not impressed by several Paradigm speakers, B&W 683/5 series, Polk Audio Rti series etc. I've had both good and bad experiences with the LS50 and Monitor Audio Silver series.


PS : I apologise for bombarding so many questions at once, I know its a long post. But I could really do with some advise, as this first build is probably going to be my main speaker set for a coming few years.

A big thanks to the forum, and especially to Mr.Bagby for providing us these invaluable designs, it really helps young newbies like us to confidently step into this world.

Regards
 
TL Continuum

I have heard the mass-loaded TL version Maynard created from Jeff's Continuum design, and Jeff himself described it as a "Continuum with bass"! In a small room like yours I doubt you would be feeling any need for a subwoofer. I design only TLs of one form or another and Maynard did a very good job on his version of Jeff's creation.
Paul
 
Thanks for the reply! That helps a lot. I certainly do consider building the MLTL version.

As I've never built a TL before, do you think it adds significant difficulties in the build process for the cabinets?
MaynardG:
Also ,

Internal height of the MLTL is 40". Internal cross section is 6.5" X 5.5". Woofer is 7.75" from the top mounted on the wide face. Port is 2" x3" mounted 2" above the bottom (internal). Stuffing is .75 lb / sq ft in the top 1/2 only

is the only information I could get from that thread. Is there a good resource I could use to find out how to build a MLTL speaker?
Thanks again!
 
You have about all the info you need to build Maynard's ML-TL design and it's really not at all difficult:
"Internal height of the MLTL is 40". Internal cross section is 6.5" X 5.5". Woofer is 7.75" from the top mounted on the wide face. Port is 2" x3" mounted 2" above the bottom (internal). Stuffing is .75 lb / sq ft in the top 1/2 only"

You will need to mount the drivers on the baffle the same distances from the top and sides as on Jeff's version stand-mount version (I'm assuming you have that info) in order to be able to use the crossover as Jeff designed it (Maynard specifies the woofer's center to be 7.75" below the top (although he doesn't say whether that's an internal or external reference). The internal dimensions of the box are as Maynard lists, 40"H x 6.5"W x 5.5"D. The center of the mass-loading port is located 2" above the internal bottom (38" below the internal top), and the port has a diameter of 2" and a length of 3". The stuffing density of 0.75 lb/ft3 translates to about 5 ounces of polyester fiber uniformly installed in the top 20" of the cabinet.

You probably ought to add some braces, like a couple of "window" braces, one just below the woofer and another about 1/2 way down from the first one.

Thanks for the reply! That helps a lot. I certainly do consider building the MLTL version.

As I've never built a TL before, do you think it adds significant difficulties in the build process for the cabinets?
MaynardG:
Also ,



is the only information I could get from that thread. Is there a good resource I could use to find out how to build a MLTL speaker?
Thanks again!
 
frugal-phile™
Joined 2001
Paid Member
You probably ought to add some braces, like a couple of "window" braces, one just below the woofer and another about 1/2 way down from the first one.

Braces should run the length of the line, both because they are more effective and they do not cause constrictions in the line.

We have done at least 1 set of builds were the original designer used window braces in his ML-TL and one with braces running vertically. The latter was significantly better. I just burned the boxes of the standard pair.

To the OP, i would forget about adding a sub to the Continuum for now, you don't have the budget -- build the ML-TL, it will get the most bass extention out of the driver. Spend more on the amp. And with your limited budget i'd personally consider a FR system.

An ML-TL looks like a BR but has one significantly longer dimension… some consider them to be BRs, but Martin King clearly showed that it functions quite differently from a BR. Many have built BR in a high aspect ratio box and complain that the tuning was off (a result of the BR software not dealing with the ¼ wave resonance.

dave
 
Thank you, Paul, for your valuable advise! It seems the MLTL version isn't that hard to build. I am however confused as to how the poly material will stay installed in the top half and not fall, do I have to add another brace to support this? I had initially assumed TL speakers had an inner angled channel that guided the air away from the driver and that it complicated the box.

For this version of the Continuum, can the crossover remain inside the poly area(top)? Will it mess with the air volume required? Thanks again!


@Dave, Thank you for that input, I'll keep that in mind. I can do the MLTL build for under 500 I assume, leaving as much for the amplifier. I am open to considering Full range designs, only that I haven't ever heard them and that slightly worries me - I have heard several 2-way bookshelves and kind of know what to expect from them. That said, which FR design would you recommend that could in sound quality(most importantly clarity, imaging, separation and natural mids and non-harsh highs) match the Continuums? I did enjoy looking at some Frugal horn builds, I wish I could hear them though!

Thanks again!
 
frugal-phile™
Joined 2001
Paid Member
The fill that you put into a TL has to be well teased… it usually stays in place just with friction. If you are worried about it falling, a screen can be installed to hold it up or the hook part of velcro attached to the walls.

40g (1.4 oz) of acoustastuff teased compared to the same in the bag.

40g-acousta-stuff.jpg


Interesting your mention of the Frugel-Horn, i was thinking a set of FHXL with A10p or A10.3 would satisfy your criteria (that was what i was thinking when i posted the comment above), and with no XO produce a better image/soundstage and a degree of continuity very hard to achieve with any speaker that has an XO. 2 sheets of ply & the drivers ($220/pr for a stock set). Sounds like you have tools available. Cutting is trickier than a rectangular box, assembly not that difficult.

<aside> i am not a big fan of translam construction. Usually very wasteful, and you are not using the material in the direction that it works best in. Braces are not as effective (unless you cut them separately and they are 1 piece and run perpendicular to the layers in the translam). Good for creating unusual shapes thou.</aside>

Where in the US are you? Perhaps we can find a set for you to audition. Do note that 2-ways vary in quality as much as any other speaker, listening to one example tells you little about others.

What are you using as source? i suspect you will need more "other" than just an amp -- as to amps i can highly recommended the PASS ACA kits available from the diyAudio store. $300 and they sound like they have way more power than their rating would suggest. Even with my least efficient speakers & my big room, rarely do i hear them clipping. Leagues better than the Marantz and better than the TI based Class D amps (which are very good value).

dave
 
Dave, I agree that vertical braces will often be a better choice, but this box is so small in terms of width and depth, I wouldn't think it would be that much more advantageous and I wanted to use the "KISS" method.
Paul

Braces should run the length of the line, both because they are more effective and they do not cause constrictions in the line.

We have done at least 1 set of builds were the original designer used window braces in his ML-TL and one with braces running vertically. The latter was significantly better. I just burned the boxes of the standard pair.

To the OP, i would forget about adding a sub to the Continuum for now, you don't have the budget -- build the ML-TL, it will get the most bass extention out of the driver. Spend more on the amp. And with your limited budget i'd personally consider a FR system.

An ML-TL looks like a BR but has one significantly longer dimension… some consider them to be BRs, but Martin King clearly showed that it functions quite differently from a BR. Many have built BR in a high aspect ratio box and complain that the tuning was off (a result of the BR software not dealing with the ¼ wave resonance.

dave
 
Oh, cross braces would be just fine or a number of wooden dowels at various places. I prefer window braces because I dado them into the side panels, or back and baffle, which allows me to build a really square cabinet very easily. As to how much a window brace would restrict the cross-section, it all depends on how large their members need to be based on the cross-section's dimensions. You're certainly entitled to your preference just as I am.
Paul

In that case horizontal window braces would significantly restrict the cross-section, even more reason to not use them. And why is a number of horizontal braces more difficult than a vertical brace? Or even a cross?

dave
 
frugal-phile™
Joined 2001
Paid Member
I like to build really solid boxes that are unlikely to resonate.

Dowel cross-braces are unfortunately the least effective, but better than nothing.

Internal cross section is 6.5" X 5.5"

Even if the window brace is only 1" wide that is a restriction down to 44% of specified cross-section (in this case).

With the driver on the wide side, a single vertical brace, front-to-back, just off-centre would do. The brace can also allow the midbass driver to be braced against the back to reduce the load on the baffle. With 15mm ply a holey brace that is 30-40% holes would dictate a 10mm increase in the width of the box.

dave
 
The fill that you put into a TL has to be well teased… it usually stays in place just with friction. If you are worried about it falling, a screen can be installed to hold it up or the hook part of velcro attached to the walls.

40g (1.4 oz) of acoustastuff teased compared to the same in the bag.


Where in the US are you? Perhaps we can find a set for you to audition. Do note that 2-ways vary in quality as much as any other speaker, listening to one example tells you little about others.

What are you using as source? i suspect you will need more "other" than just an amp -- as to amps i can highly recommended the PASS ACA kits available from the diyAudio store. $300 and they sound like they have way more power than their rating would suggest. Even with my least efficient speakers & my big room, rarely do i hear them clipping. Leagues better than the Marantz and better than the TI based Class D amps (which are very good value).

dave


Thats really great info, especially the picture of it. You are very helpful!

I'm based in Atlanta GA, and true I would like an audition before building anything. Ive heard great things of both the Frugels and the Continuums so its hard to decide, unless someones really heard them both.

the Amp camp amp looks amazing and really fits my needs I feel. I can go in for the bare parts kit for 150 and figure out a cheaper wood/aluminium/heatsink chassis for it.

As a source I was thinking of going a (some sort of) Raspberri Pi/Hifiberry/Sabre dac way under 100$, as most of my listening is digital.
It will also be useful as a preamp with volume control to feed into the ACA.
I haven't looked into that as yet, I thought I would think of the speakers and amp first.

Thanks again, please let me know if there are people in Atlanta with the builds in the thread!
 
frugal-phile™
Joined 2001
Paid Member
Thanx for linking to that paper.

As they say in the paper, its more a poke to get people exploring than definitive. The 1st 2 problems i see are that he is only using the excitation energy from the air in the box (much more is transmitted directly from the driver to the box), and the exemplar they used for the box panels in the sim is crappy plywood.

dave
 
Jeff Bagby Mandolin speakers are a noticable step up. The SB17NRXC has a very low inductance motor which smooths the high frequency crossover region. The soft dome has good HiFreq extension with a resonant-free gentle roll-off.

If you download specs on the two SBAcoustics drivers you will buy the Mandolin. There are also diyAudio threads on 3-way designs which add 8" or 10" woofers to these drivers to leave some dreams ahead. Parts Express often has sales on good pre-built cabinets...just route the baffle.

$350 - $375
The kit features drivers from SB Acoustics. Please click the pdf link below to read Jeff's design process and overall description.

All parts are included to build one pair of kits, except for the cabinet. Plans are included.

SB29RDC, Ring Tweeter
SB17NRXC-8-UC, 6.5" Mid Bass - we like the uncoated, but there is no performance difference.
Assembled Crossovers using PulseX caps and our inductors.
Big Post, binding posts
Internal damping material
Port Tube Hook Up wire Mounting screws.

Mandolin Speaker Kit / Pr
 
I just finished test cabinets for Mandoline. I must say that the room they are in is similar to what the OP said his speakers will be listened in.

For my ears, Mandolines are too bass heavy. The room goes into equation but lower midrange sounds muddy too. Since I made large coil on the bass out of two smaller coils 1.4mm thick wire (1mH+1.5mH=2.5) i bypassed the 1mH and it immediately started to sound better. In larger rooms and with more potent amplifiers it may sound better to go with JB xover but in smaller rooms something has to be done with that heavy sound. I am preparing to make frd and zma files this weekend to make the crossover that suits me.

P.S. If you are to be in a smallish room for a few years i'd suggest not to put ports on the rear of the cabinet. Make the cabinet a little taller and put it on the front side. Rear ports in small rooms where speakers are near the back wall sounds just awful.
 
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we are fortunate to have mikejennens on this forum. He has built both the MA 7.3
Frugelhorn and the MLTL Continuum. The latter was easily my preference. You could ask him about the 7 3/4" measurement from the top. They went down to maybe 50 hz but I would not use a sub with them. Integrating subs with speakers is not for the feint of heart. Mike had them in a much better room than
yours, maybe double the size. Coincidentally he also used a (relatively) inexpensive
Marantz amp (PM8003). Recorded music was played at a med. vol.

Please describe what you mean by medium volume. I agree with the front porting.
I would used plywood myself. I use Frostking damping sheets from Home Depot
to limit cabinet vibration. Very cheap and very effective. does not eat up a lot of internal volume. Dave's bracing scheme would be great but be sure to account for
volume losses regardless of how you brace. External strip bracing can also be used
instead! think L shaped supports that brace ea. side and come out from the speaker
at the bottom to form extensions to keep the things from falling over.

The J. Bagby speakers were some of the best I have ever heard at any price, and I have heard a few. Cheap caps in the xovers too, so they could be upgraded when you come into some dough.

Every speaker has its limits. What is loud to one person is soft to another. Forget about low powered amps with an 83 db/watt/meter speaker.

Can you be happy with 90 db? Go with the MLTL.
 
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Thanks for the great inputs guys! After reading all this I still feel, without getting a chance to listen and for my room, the Continuum MLTL will be fit. The Mandolin did seem a big speaker for the small room, somewhat like the Kairos. Boomy bass and lower mids is not a problem I want to solve. I haven't heard if the Tributes are better than the Continuums, and the MLTL possibility does seem intriguing. Argh, decisions!

Would you say the Amp camp amp (Class A), recommended kindly by Planet10, might not drive the MLTL too far even for the small room? Its hard for me to understand what 90dB is, with no way of measuring and no speakers currently. I would say medium is (definitely) lesser than live music, but still loud to a point where I can hear subtle details, all instruments and voices clearly and well-separated.

I have another question regarding the amplifier : If I use a Raspberry Pi + (sabre 9023 based dac) directly feeding the amplifier, will the impedance matching be a problem? Do I have to use a preamp between the two for the sound to "open up"? Im sorry for the silly questions, I just have read a lot of these things without really experiencing them myself. My budget won't allow me to experiment for an A/B comparison in most cases.

If the ACA is not powerful enough, which other DIY build/preused buy would you recommend?

Thanks!
 
If you want to use this first build for some education on crossover circuits and cabinet construction, you could purchase the speakers from Madisound for ~$220/pair +ship, and start with a standard crossover topology which you could simulate with free Xsim, and gradually "tweek" to match your ears, cabinet, and room. Xover parts ~$80/pair + ship. After a few Xsim runs, you will be able to select useful extra R-L-C parts to add to your order for experiments.

There are MLTL cabinet designs for the SB17NRXC-8, as well as 3-ways from adding either the 8" SB23NRX45-8 or 10" SB29NRX75-6. A well designed 3-way will always sound better than a 2-way MLTL, because the midrange can now use a superior transient sealed box without large Xmax low freqs.

SB29RDC, Ring Tweeter ~$52 Madisound
SB17NRXC-8-UC, 6.5" Mid Bass - $58 Madisound
Highest quality/$ that I could find.
 

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