Efficient 2-way

In the past I've build two guitar tube amplifiers, moved on to a tube hifi stereo amplifier (6V6 PP 10-15W) and I've been contemplating building a loudspeaker for quite some time now. I started researching the Klonwall and made CAD drawings, went to 3-way, looked at Full-Range, was pointed towards a transmission line speaker by a colleague, started designing crossovers using VituixCad, discovered active crossovers: I've read so much I forgot most of it again...

At the moment I think I would like to build an efficient 2-way, (12" - )15" woofer with a compression driver, like e.g. ToneMaster (https://audio-creative.nl/projecten/audio-creative-tonemaster-ii/), Calpamos (http://www.humblehomemadehifi.com/download/Humble Homemade Hifi_Calpamos.pdf). As everything is a first I plan to do quite some research and designing on the computer. Therefore I plan to use e.g. a miniDSP 2x4 HD as an active crossover with a UMIK-1 to measure SPL. I have a (second) SS amp I can use for the time being. I've used REW for testing my tube amplifier and made myself a little box to measure speaker impedance curves with it. I feel the active crossover will allow me to let me experiment with e.g. different crossover frequencies (which I consider as part of the journey); after I've measure the drivers in the actual enclosure. Eventually I might build a passive crossover, we'll see what happens.

Now the questions:
Any great drivers? (100 to 200 euro per driver, you get bonus points for cheaper, yet good, drivers)
Any general advice?
Any (other) examples?
Books to read?
miniDSP alternatives?

As you might read between the lines I have a severe case of analysis paralysis and 'choice stress'.
Take deep breath and loose some focus for a minute, to see the big picture! :) What is it that you are after? nostalgia, top sound, good nice party, decor, all of them? Does size or price set limitations?

All speakers are bunch of compromises, and there are million details to consider as you have starting to discover. It is a good thing that you've already narrowed focus to tube amps and found out you'd probably be better of with high efficiency speaker. Usually these come with size and cost, are you prepared?:) This is usually good thing for audio quality, size and cost have been compromized for audio quality. Just watch out for marketing traps, there is no need to pay extra! I think there are good drivers available quite cheaply and it is matter of the whole speaker system design which drivers are needed and how it will sound eventually. Popular kit is very good way to start, it makes progress and you'll learn tons!

So please take your time, read anything that feels relevant and interesting. If something is too complicated leave it aside and come back later when it feels relevant. Build, especially prototype. Question anything you see on the forums, many don't build nor prototype. Big speakers can be pain in the butt to build, big and heavy so even if it is a kit preparing to have one failed cabinet (build prototype) will make you learn more and have nice finished pair eventually, instead of forcing it through and patching the first timer mistakes and then be unhappy with the results.

Questions like why would TL be better than closed box? is there something even better? what is the trade-off with it? Why is the speaker 10x the size than the other? Which one would suit my application better?

You'll learn there is always a trade-off or two to any design decision you do. Try to make sure trade-offs don't prevent you to reach your goal! For example, If you have size limit, then there is ceiling to SPL and/or bandwidth ( low frequencies are big, size of your listening room)!

Remember to think the big picture every now and then, what is it that you are after. I've found out there is roughly two camps in the forum, those who don't know what they are seeking and those who do :D

Most importantly, have fun! :)
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2010-03-02 9:29 am


The Asathor is a very affordable and solid design along the lines you proposed. Although not perfect -i.m.o the x/o is a bit too high for controlled directivity- it is a lot cheaper that the Calpamos.

For a more fundamental approach of the design of such a system, have a look at the 2-way-waveguide thread. Member Fluid demonstrates amazing skills and insight there.

Good luck, but start with a lot of reading first of all.


2009-07-12 12:38 am
Look at "Econowave" designs. 12" pro woofer + 1" compression driver and horn in a simple cabinet. It's a boring and ubiquitious design, but checks most of the boxes for "good sound" with no glaring flaws. Many combinations of drivers, horns (at all price points) and passive crossovers for them have been documented to the point of exhaustion. I've built this style of speaker with Dayton PA310, Faital 12PR300 for the woofers, B&C DE250 and Faital HF10AK for the highs. All very good, but I especially like Faital products.

By the way, using a tube pre-amp and a clean and efficient Class D power amp can give you the best of both worlds in amplification. If you spring for IcePower or Hypex plate amps with DSP you can have a versatile and convenient platform that can be recycled over and over again as you refine your tastes and build new speakers.
Personally, I pursue accuracy in reproduction, with maybe 110 db peak levels in my 3.5 m x 11 m x 2.5 m room.
Standard, piano CD/LP tracks should sound like my $3300 Sohmer 39 or used Steinway 40 pianos.
Best approximation heard yet in the flyover city, 15" woofer + 1.4" CD on plastic horn, Peavey SP2(2004) . I disdained the bass notes of their 12" woofer+1.4" CD model, the SP5. I disdained the overall sound of their 1" CD +15" woofer model, the PV15. I listened in store at about 1 W. Below 5 W SP2(2004) plots 2nd & 3rd harmonic distortion >20 db below response 80 hz - 12 khz. No other speaker I've seen asserts a limit on HD.
So I bought an approximation at 1/2 the price, SP2-XT, which has the same drivers and 3/5 the power rating, because they are crossed at 1200 hz instead of 2000 hz. Bonus, the SP2-XT has 3 db point of 22.5 deg off axis from 500 to 16 khz, so you can walk around the room without the sound changing.
I loved SP2-XT. So did the burglar, that carried them off along with all amps, mixers, wires, 2600 LP & 200+ CD.
So I'm building a very ugly replacement that will have no pawn shop value. It will be MDF with clear urethane finish for a very ugly appearance. There will be steel grills from the home store. The port will be a toilet flange. 1.4" compression drivers RX22 are available used with horns on ebay. Or new drivers are $160 .
Woofer 1505-8KADT is still available from Peavey. Since Peavey production is now in a country that caused me a lot of trouble in my 20's and is worse now, I bought eminence deltapro-15a that is made 30 miles from here. Ron G Went to a lot of trouble showing how to compensate response loss of the woofer steel frame with a shorting capacitor. Since shorting capacitor across woofer cause impedance loss and soaks more current I bought aluminum frame woofer. Still 101 db 1w1m. Since you are contemplating using a tube amp, you should enjoy a 101 db 1w1m speaker, which the SP2-XT was. The SP2(2004) is 98 db.
As an alternative to the DSP programmed with a cell phone made in the same country that caused me to be drafted in 1968, I bought 2 used 32 slider graphic equalizer for $50 each. Built in Mississippi. You'll still need some kind of tweeter protection on a CD, at least an 8 ohm resistor series a 15 w tungsten auto bulb. Dropped microphones or pops from lightning or cable pullout can damage tweeters. RX22 CD has 111 db 1w1m response compared to 100 db woofer, so tweeter needs some padding down anyway. I will cross 1200 hz first trial, deltapro-15a response rises above 1000 hz and I don't need the beaming with a 1.4" horn handling above 1200.
Response microphone not bought yet. Circular saw not bought yet, the same burglar carried off $35000 in tools. I just lost my use of a woodshop in a nearby church, they are hiring pros to build their organ. Speaker box can be sealed or ported, eminence deltapro-15a will go either way with Qt .4 . Eminence also sell kappapro15 with Qt .32 for ported only. First cut I'm going to try for 3 db point 54 hz, although if I limit power to avoid tearing the woofer suspension, I might be able to push Q3 down to 40 hz. Pianos go down to 26 hz.
Box math is in David B. Weems Designing Building and Testing Your Own Speaker System. If you have a windows computer, vituixcad which is a free download is available.
I'm trying to keep box <25 kg so I can lift it on poles over the organ without hiring a mover @ $330 for 2 hours. CD horn needs no box IMHO, will be mounted on pole separately. First cut front will be 3/4 plywood Sahel from HD, "baltic birch" is not available in US home stores. Sides top back will be 1/2" mdf. Some indication 1/2" MDF will vibrate too much, but if I keep the sound pressure down I won't need a 84 lb box like the SP2-XT was.
Other candidate woofers talked about are fatal15pr400 aesspeakers TD15x-8 McCauley 8341-8 (aluminum)
Other candidate 1.4" tweeters eminence and p-audio. I don't need 16 khz to 20 khz, my hearing stops at 14 khz due to draft status noted above.
Happy shopping planning & building.
Thanks for the answers so far.

I'm definitely going for 'top sound', up to a point. I'm a music lover that appreciates good sound, but my ears aren't trained enough to hear all the differences people hear or think they hear. I'm not a snake oil kinda guy, more of a science kinda guy.
Budget wise you should think 500-1000 euro. 4 drivers, wood is expensive, all the small stuff: it adds up. That is without the miniDSP. Size is not that big of a deal, looks also not that big of a deal. Although, somehow, the econowave is... how shall I say this... hideous :oops: I don't know if it's the size, the color or the horn.

I've read the Asathor thread and the website. My German has been better, but I managed. Nice cheap drivers. However, Faital Pro seems to pop up everywhere. Especially the 15PR400. Prices differ a lot, but I found them for 168 euro a piece (without shipping). The compression drivers are quite expensive though. And will I ever hear the difference, given my untrained ear? I'm willing to pay something extra for quality stuff, but again, up to a point. Is there any data in the datasheet I should look for? Few peaks in impedance graph? Smooth frequency respons? Motor strength? ...?

The link about ABEC modelling is too complicated for me.

I planned my tube amps meticulously and my prototype is my amp. With hardware being quite expensive, I'll try to limit physical prototyping. I hope the miniDSP will give me quite some flexibility regarding the crossover. In one of the sticky threads I found crossovers are very important.

@indianajo : I will need some more time to decipher your post. ;-)


2010-03-02 9:29 am
Even the so called (self proclaiming!) trained ears are claiming all sorts of differences, which in a blind test they would never be able to determine. Boutique capacitors or wiring for example, but cone material is another.
Furthermore, the line between hi end audio influencers and just for fun hobbyist designers is sometime a bit blurred.


2009-07-12 12:38 am
will I ever hear the difference, given my untrained ear?

a lot of expensive pro drivers are designed to deliver marginally better performance at high output levels. so for home use, not worth paying for IMO. but a two-way speaker uses components at the outer frequency limits of their design envelopes (4+ octaves per driver) so I pay attention to good behavior "at the edges."

things I think are worth seeking out:

a woofer with a natively smooth response at the upper crossover. most high sensitivity woofers have a peaky break-up. even if you stomp on it with EQ it still muddies the vocal midrange. Faital has done a better job than most at keeping the break-up under control without damping the life out of the cone.

compression drivers with a polymer diaphragm sound smoother and more natural to me. the vast majority of compression tweets are titanium. once again, a break-up thing. i think I can hear a difference, even at moderate power levels.

the acoustic qualities of the horn you choose is going to have the biggest impact on what you hear. that's a big can of worms. I started out by trying horns that other people said are nice sounding. that's one area where subjective opinions seem to be worth relying on in making a decision. and there doesn't seem to be much of a correlation between horn price and sound quality, it's more about availability.

best piece of advice I have is that a sound system isn't just a collection of parts, it's a system. it's better to have everything "pretty good" and working harmoniously than to obsess over a single parameter. there is no "magic bullet" for great sound. you can make a great speaker out of budget parts. have fun!
I'm definitely going for 'top sound', up to a point. I'm a music lover that appreciates good sound, but my ears aren't trained enough to hear all the differences people hear or think they hear. I'm not a snake oil kinda guy, more of a science kinda guy.
I think if your hearing is not destroyed by fireworks, firearms, loud motors, extreme volume concerts, (95% of males over 12 are deaf IMHO) you should be able to hear the difference between 10% hd 1% hd and .1%. Also -3b 26hz-7khz in certain key areas like the bass. My hearing goes to 14 khz, tested at work. There are a lot of adjectives about amps & speakers people use I find mysterious.
Go to some live acoustic concerts. Difficult to reproduce accurately sounds: piano, tinkly bells, taut bass drum, low notes of double bass tuba or organ (missing), mid range violin & voice (can get screechy). Then listen to CD's or unworn LP's with headphones. Even $29 headphones can be very accurate.
Whereas with speakers, some high sounds get hissy (IM distortion). S consonant in voice can hiss. Some tones vibrate in pitch, which instruments like piano cannot actually do. (IM distortion) Screechy violin & voice can get very annoying over an hour or more. Bass if the box has a hump in the response can get boomy. Taut bass drum hits can swoop in frequency if a speaker has different length sound paths for different frequencies (foldhorns).
I've had half decent amps since 1970, but accurate speakers were out of range of my hobby fund until I retired. 1% HD is slightly fuzzy (dynaco ST70) 0.1% HD more like reality (Peavey M-2600, Apex AX6). .03% HD amp (CS800s, CX302) versus .1% I can't hear a difference. Amps with a wattage limit caused by bad capacitors I can hear; the music is polite with no attack on notes (like piano that has a huge attack transient).
It is amazing what speakers are pretty good. $2 2 way speakers with a 2" woofer from Salvation Army are pretty good until source goes really high or low or volume goes over 85 db. Coax 6.5" drivers salvaged from a Mitsubishi projection TV in a vented cardboard box 14"x9"x9" sound pretty good except for low bass and top octave piano. Getting the top and bottom ends of response gets price up to $600 each new, or $200 ea on the used market. My eminence Delta-pro 15A drivers were $259 ea and the Peavey 22XT used horns were $170 the pair. I'll have a chance to audit the titanium diaphragm CD versus the organic one with those, one horn is a 22XT (titanium) and the other is a 22A (organic). I think I already own a 22A CD in a floor monitor, and I really can't hear the difference IMHO, although the SP2(2004) are in town and the Peavey CD+15" floor monitor is 30 miles away at summer camp.
Rock & pop music you can't tell a lot about how it was supposed to sound. I listen to a lot of it but accuracy does not describe electric guitar. Some people like a boost 1-2 khz on voice, makes it interesting.. Some voices are recorded that way. This is the kind of effect I would rather put between player & amp with a graphic equalizer or DSP. Leave the speaker accurate for non-voice tracks. Same with reverb or ambience. Put it in with an effects unit if desired.
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2009-01-24 2:20 pm
The link about ABEC modelling is too complicated for me.
Fair enough, but you don't have to understand the method to see the results and learn from them.

The first choice to make would be the waveguide/horn as that will dictate some choices. Are you aiming for a 1" throat or a 1.4" throat?

The waveguide used in the Asathor the Celestion 9040P is not bad

Here is a review in Audioexpress where it is used with a Celestion CD, Celestion make a few 1" drivers that are pretty good for a reasonable price.


There are not that many good choices in 1" waveguides to match up with 15" woofers, a 12" may end up being a better directivity match at the likely crossover point with a lot of 1" guides. If you don't have a subwoofer or intend to use one the 12" drivers will not likely reach quite as low as the 15's if choosing pro drivers.

1.4" waveguides are more often used to match with 15" woofers as the drivers have more output lower in frequency and the size of the waveguide tends to help match the directivities at a lower frequency.

The XT1464 is a good choice in 1.4" waveguides but the pattern is narrower, the Faital HF146 measures very nicely on this waveguide.


JBL have this 1.5" horn that is used in the 4722N Cinema Speaker, pretty big and needs a 1.5" driver of which JBL and 18Sound have some good ones, not likely as cheap as the other choices.



From there you move to 2" guides and drivers. The top end can get ragged on a 2" driver and the physical size of the source will mean that it drops off faster at higher frequencies as you move off axis, some guides like the 2380 use a diffraction slot to make the directivity more constant, but not everyone likes the result


All the pro manufacturers make good woofers, Faital's 15PR400 and 15FH500 are well liked and would perform well, 12PR320 is popular too. The Eminence Deltalite's are another reasonable choice as would be B&C or 18sound. It depends on price and availability, I don't think you would go wrong with any of them.

The Asathor and Calpamos should give you some good ideas on cabinets, and Troels Graveson has many pictures on his site of reasonable construction methods.

First thing to decide is pattern width and driver size in an available well measuring waveguide, most other choices will flow on from there.

Hopefully this helps you to narrow your choices rather add to your confusion
Fair enough, but you don't have to understand the method to see the results and learn from them.
I've tried again, but still can't filter out the results.

There are not that many good choices in 1" waveguides to match up with 15" woofers, a 12" may end up being a better directivity match at the likely crossover point with a lot of 1" guides. If you don't have a subwoofer or intend to use one the 12" drivers will not likely reach quite as low as the 15's if choosing pro drivers.
Going with the 12" version should half the volume of the enclosure. Also the CD you give with its horn is very cheap with respect to the 1.4"en 2" options. 2" might be too large right? Any cheap(er), yet good, 1.4" CD's for the 15" woofer? 12" might be a better choice...

you said I needed to decide on pattern width. I've no idea. What would you advice?

In the mean time I'm taking the first steps in enclosure design, baffle step, bracing, damping reading and 3D CAD drawing.

Build threads are always nice. Having little experience has the advantage you learn fast :)


2009-01-24 2:20 pm
Going with the 12" version should half the volume of the enclosure. Also the CD you give with its horn is very cheap with respect to the 1.4"en 2" options. 2" might be too large right? Any cheap(er), yet good, 1.4" CD's for the 15" woofer? 12" might be a better choice...
There are a number of good 1" that don't cost too much still, some of the BMS drivers like the 4550, RCF ND350, B&C DE360 can all still be found for a reasonable price, TLHP tends to have the best prices. There are other horns from Sica, RCF and 18sound that are worth looking at too. The tymphany driver used in the Asathor can reach a bit lower than some others and is popular.

In 1.4" CD's the Beyma 1014 range is still cheap and good, some of the Oberton drivers and the older BMS 4555 and 4554 but they have less output than the 4550. Faital used to be good value but their recent price hike and lack of availability is against them right now.
you said I needed to decide on pattern width. I've no idea. What would you advice?
Most horns/ waveguides will have a nominal pattern size 90x40, 90x60 or 60x40. That is the width and height in degrees where the pattern is relatively constant to gently rising with frequency. Most people tend to prefer a wider pattern in general but 90 degrees is still narrow compared to most hifi tower speakers.

Do you want to cover one seat, many seats or the whole room, the narrower the pattern the more focused it will be towards a smaller area with the sound changing more the further you move away. The flip side is that the wider the pattern the more the room sound will be returned. This is a pretty big subject with no clear "right" answer.
Hi Tom,
I have a quite "hard" room room which is also large at 45sqm. Going from a horn with 90x40 radiation to 100 in a coaxial driver was eye opening. I had to dampen the front wall with the coaxial. Try to find a shop which sell PA stuff, I listened to RCF's ART series before I bought my horns. As I recall, this ART serie consist mainly of 90x60 horns, my 90x40 is a bit narrow in the vertical angle. I like to move when listening also...
Build, especially prototype.
First prototypes ready.


The Calpamos are roughly the same size as the dogfood cardboard boxes. Fortunately my pile of paper and cardboard is large enough that I found two of them.

When I drew the woofer, their size struck me. However, the horn size was the real surprise!
There are currently two (new) 15PR400's and two (new) HF144's on a (second hand) trading site (€125,- each). Seems like a good deal.

However, I really like the look of the PH-2380, but it is 2" and availability is not great (for reasonable prices). Adapters are also hard to find. Are adapter any good? Can I make my own from a piece of wood with a conical hole?
I'm not able to find many 1.4" horns. And those that I do find: wrong angles, way smaller or not flat, shiny and plain ugly.

Am I looking for square circles?
The speaker/listening positions do not seem to be ideal, especially for large horn speakers. You can absolutely find better positioning if you can prioritize things for better sound.

Calpamos looks good and very reasonable to me. Should be a good speaker.
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