Full Range Cabinet for Archtop Guitar & Crossover Questions..

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Hi, I'm new to this forum; I hope someone here can help me with my guitar cabinet dilemma!

I'm looking to build, buy or modify a lightweight guitar cabinet for use with my fully-hollow archtop guitar. The guitar has a single magnetic neck pickup and an internal DPA mini condenser microphone; I like to blend the two sources together or switch back and forth between the two. I may eventually replace the mic with a transducer-style acoustic pickup to reduce feedback issues but regardless, one of the sources will require a full-range speaker system.

I have a couple of old octal tube amp heads that I use at home, but for gigging purposes I will probably go with one of the many small solid state amps that are currently available - Quilter, Acoustic Image, Henriksen, Raezer's Edge, etc., so I'm looking for a passive, full-range speaker cabinet to use with one or more of these amps. I would also like to use the same cabinet for acoustic guitar.

Finding a cabinet that sounds equally good for both electric and acoustic guitar pickups usually requires some sort of compromise and I'd like to get some advice on this subject. Eminence alpha/beta speakers and front ported/closed back Raezer's Edge cabinets with adjustable tweeters are the usual choices in these circumstances, but these eminence speakers are not the first choice for most electric guitarists. Also, these Eminence speakers have a limited frequency range that tops out around 3500 hz, which is not ideal IMO. My understanding is that archtop guitars have a harmonically rich spot between 4000 & 6000 hz, and ideally the main speaker would have a range that would include these frequencies.

I had a thought: I have access to a NOS EV Force 10 speaker, which has a range of 75 - 7000 hz, and am wondering if perhaps this would be a good choice. Along with the Altec 417, 425, etc., I think the EVM/SRO speaker lines were originally designed as more of a general purpose PA and musical instrument speaker (correct me if I'm wrong); they just happened to be a great choice for electric guitar cabinets. These speakers all have a wide frequency range topping out in the 6000 - 8000 hz range.

So my questions:

Would the Force 10 match well with a tweeter/crossover/LPad for an extended range closed back ported cabinet? I realize that these are heavy speakers (EV Force 10 is 13 lbs, for example), but perhaps a lightweight pine or 1/2 plywood cabinet could make up the difference.

What sort of crossover should I use? Passive or active? What frequency should the crossover happen at? What tweeter? Cabinet design recommendations?

I'll consider anything that would be suitable as long as it is not overly large or heavy. Thanks for your time and stay healthy!
 
your barking up the right tree in my opinion with the EV Force 10 but if it was an EVM12L you'd be all the way home IMHO and tweeters would be a non issue.


no correction necessary the EVM/SRO line was intented as such but let's keep in mind the philosophy of the era was that linearity and distortion where the enemy so yeah if your after clean tones and lack of cone breakup that distortion fanatics prize, the EVM12 L is worthy in my opinion (i like em so much i once used them in the mid of my pa system )


can't coment on the Altec 417 as i can't recall ever hearing one but it's pedigree would suggest it would work well.
 
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oh and keeping any form of crossover out of the picture when it it come a musical instrument signal is best... but that just stems from my time as a live sound tech....


i hate trying to mike an amp that has a multi source speaker configuration ....i get lost on where to put the mic...and if i gotta use multiple mikes how do i sum the phase to make it coherent through the PA....time for a scotch and some contemplation.
 
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your barking up the right tree in my opinion with the EV Force 10 but if it was an EVM12L you'd be all the way home IMHO and tweeters would be a non issue.


no correction necessary the EVM/SRO line was intented as such but let's keep in mind the philosophy of the era was that linearity and distortion where the enemy so yeah if your after clean tones and lack of cone breakup that distortion fanatics prize, the EVM12 L is worthy in my opinion (i like em so much i once used them in the mid of my pa system )


can't coment on the Altec 417 as i can't recall ever hearing one but it's pedigree would suggest it would work well.

Hey, thanks for the response, much appreciated! Happy New Year!

From what I have seen from the spec sheets that I have found, all of these speakers we're talking about (EVM, SRO, Altec, Force, etc.) have a similar frequency range ending in the 6000 - 8000 hz range. For example, an EV Force 12 has a range of 60 - 7000 hz, 99 db, and my Altec 417-8C has a range of 60 - 8000 hz, 100db.

I was thinking about the Force speaker line instead of the EVM because it is 150 watts instead of 200 watts and several pounds lighter; I believe that these were specifically intended for guitar amps and were built due to the success of the heavier units.

Two problems I see, however:

1) I see your point about not having multiple speakers and crossovers and that this is a better way to go, but since my fully-hollow archtop has an internal condenser microphone that I'm blending with the magnetic pickup, I don't see any of these speakers managing the frequency range of the mic on their own. I need double the frequency range that any of these speakers can offer. Also, I would like to be able to use the same cabinet for my acoustic guitars.

2) These speakers are way louder than my application requires. I am thinking home practice, band rehearsals and small to medium sized venues. I don't imagine I will ever be putting enough power through these speakers to get them to their sweet spot, plus with the high efficiency they'll be blowing my head off.

I know Celestion has recently come out with a single cone speaker for guitar modelling systems that is truly full range: Celestion F12-X200, 60 -20 000 hz, 97 db:

Celestion F12-X200 - 12in Ceramic Full Range Speaker

But again, this is a 200 watt speaker. Might be a good alternative though.

Cheers!
 
Sorry, correction - The Celestion F12-X200 still has a crossover and high frequency compression driver, but it has been built into a single unit that looks like a regular guitar speaker. I don't know precisely what is going on here, but it appears to be different from a typical coaxial speaker and apparently has been designed to solve the problem we're talking about. Most PA type systems seem to have the crossover point too low to be ideal for electric guitar; perhaps they've found a solution here.
 
Celestion F12-X200...interesting driver... would be worth hearing.


even though the mic has greater range i still don't think it necessary to have the speaker's high frequency range to go that high flat, accentuated peaky response is usually objectionable (but that's where dsp eq comes in) but a smooth rolloff above 5k i find gives a good natural tone for an acoustic guitar the harmonics are still there but at the reduced level they should be, unlike some acoustic amps with tweet's that boost that range for artificial sparkle that always sounds phony. it attracts attention and makes people take notice but for the wrong reason ....


it may be that many of the popular "acoustic amps" i've heard had piezzo tweets or tweet's that definitely where not time and phase aligned and thats what grates on me...
 
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it can be done passively but it's hadrer to get right and parts costs escalates quickly. and it does come down to the distance/time interval to be corrected.



so an active x-over that has delay functions is the best bet.


the Celestion coax is likely a good solution in that without more info i would think has the low and high frequency voice coils in really close alignment thus reducing the problem to begin with and i would think their x-over is designed with that in mind.


i still have my reservations as to needing much above 5k for what your doing.
 
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it can be done passively but it's hadrer to get right and parts costs escalates quickly. and it does come down to the distance/time interval to be corrected.



so an active x-over that has delay functions is the best bet.


the Celestion coax is likely a good solution in that without more info i would think has the low and high frequency voice coils in really close alignment thus reducing the problem to begin with and i would think their x-over is designed with that in mind.


i still have my reservations as to needing much above 5k for what your doing.

Ok, that's interesting. I will look into the Celestion a bit more, as it seems like a simple way to solve the problem. Although it does concern me that I can't turn the high end off if I wanted to when not using the mic. But I imagine that I could cut the high frequencies with some sort of EQ(?).

I admit that I may be mistaken about the frequency range required for my application. I'm micing both my archtop and acoustic guitars; my experience is that I usually get the best results from the mic when going through my PA system or one of the better acoustic guitar amplifiers on the market. (I've tried out quite a few.)

On that note, I recently tried out the newly released Genzler Acoustic Array Pro: 10" woofer w/4 x 2.5" cone driver line array:

Acoustic Array Pro - Genzler Amplification

As far as small portable amps are concerned, my archtop's mic has never sounded better than through the Genzler. However, as one would imagine, the magnetic pickup in the archtop didn't sound great through these acoustic/PA type systems, so that's the problem I'm trying to solve.

Thanks for your input.
 
8 kHz off a 10" speaker will have nothing for a coverage angle. Which is probably a good thing, keep it faced the back of your legs. A tossup for acoustic guitar. The attack of the note actually adds a little to the guitar. The problem with tweeters is that they are subject to feedback in a live setting. I have some 8" drivers that I am adding horn tweeters to at some point as monitors/PA duty for coffee shop/home concert type of situations. I am seriously thinking of biamping with them. I tried some piezo tweeters and they added some top end. They would survive the occasional abuse.




You posted just under the wire on me. I looked at the amp you posted, I thought I would rather have a cone speaker rather than a horn for the highs. I like the idea of a group of them as the amp has although I would rather they be mounted above the woofer and in a horozontal arc for the coverage angle desired. I get why the array would be more practical in a build context.
 
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does the Genzler truly solve the high to low transistion....we need to get together for a glass of scotch....and some jammin'....

Sounds good - I am a big fan of both whisky & jammin'! If you add good cigars to that, it's pretty much as good as it gets!

Incidentally, I ended up finding one of those Genzlers down south. A dealer had bought a bunch of new stock from a music store that went out of business and was selling it off. I bought the amp dirt cheap and had it shipped to a friend's house in the Boston area. I'll pick it up later - shipping to Canada is super expensive these days, and I travel to the US pretty regularly (or at least I did pre-Covid). Great little amp for acoustic instruments, and the EQ is very well designed, IMO.

I managed to contact Jeff Genzler some time ago; he said this re. the Acoustic Array Pro:

"The 10” speaker starts to roll off on the top end around 1200 - 1500 Hz and that is where the array column starts to roll in."
 
8 kHz off a 10" speaker will have nothing for a coverage angle. Which is probably a good thing, keep it faced the back of your legs. A tossup for acoustic guitar. The attack of the note actually adds a little to the guitar. The problem with tweeters is that they are subject to feedback in a live setting. I have some 8" drivers that I am adding horn tweeters to at some point as monitors/PA duty for coffee shop/home concert type of situations. I am seriously thinking of biamping with them. I tried some piezo tweeters and they added some top end. They would survive the occasional abuse.




You posted just under the wire on me. I looked at the amp you posted, I thought I would rather have a cone speaker rather than a horn for the highs. I like the idea of a group of them as the amp has although I would rather they be mounted above the woofer and in a horozontal arc for the coverage angle desired. I get why the array would be more practical in a build context.

This is my thinking as well - small cone speakers for the highs are probably a smoother sounding option than a tweeter; this seems to be the case with the Genzler.

I bought the Genzler because the price was right and it's a good choice for my acoustic guitars, but it still doesn't solve the problem for my archtop. The magnetic pickup in my archtop doesn't sound great through (which was expected), but the mic sounds stellar. Like most acoustic amps, I think (and this is a guess, mind you) that the crossover is too low (1200 -1500 hz) to be ideal for my electric guitar.

I still want to find or build a passive cab that sounds equally good with my archtop's magnetic pickup and internal mic. So let's say I wanted to build a cabinet like this using an EVM 12L or that lower wattage Force 10 that I mentioned. What active crossover and high frequency driver or tweeter should I be looking at? Or should I just get the standard Eminence Alpha/Beta + passive crossover/tweeter combination?

I know Eminence makes a 5000 hz crossover that would probably pair well with these EV/Altec speakers:

PXB2:5k0 - Crossovers | Eminence Speaker

And here's a tweeter/horn combo:

APT:80 - Supertweeters | Eminence Speaker
 
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