New sub design? Constricted Transflex, simple build (series tuned 6th order)

[freddi]

post 2000 was for a 0.7 scale University Classic S9 horn. Its still at Triticum Audio so don't know how it will do in reality - it will run an Eminence made bass guitar 10 -

here's the input I used
http://www.diyaudio.com/forums/mult...-classic-folded-midbass-horn.html#post4807724

S9 and scaled S9 - the 0.7 scale version is made of 5/8" Baltic birch plywood
and weighs 51lb without the driver
http://i.imgur.com/I8gf898.jpg

sim with 10" bass guitar speaker
http://i.imgur.com/9ulddu8.jpg

 

[mattcalf]

Thanks again for a comprehensive reply, MMJ!

Mattcalf ,
Aperture style "E" is definitely a great solution in that cabinet
The 30hz-ish tuning would be considered more ideal for movies (home theater) and will also make a fine multipurpose sub for general usage ......

There is also a low-budget way to do it with a signal generator, a resistor, and a volt meter (i could walk someone through this procedure if they wanted to try it , it is pretty easy really)

In our previous chat you mentioned connecting a lightbulb in series to the woofer, where and what value resister would I need in this test circuit?

My tuning process was going to be as follows:

• Cut aperture E arc into baffle
• Ratchet strap/clamp baffle to box
• Run test circuit at 30Hz
• Slide the baffle up or down until the bulb is brightest/volt meter reads highest

NOTE: If someone felt like they needed even more resonance near tuning with this design they could obscure part of the driver's cone using an aperture "E" with reduced arc , or no arc at all (to "shade" the top of the driver with the front panel) or add some K style wings or some such thing, but keep in mind that this would also shift the cabinet tuning downward a little (which is easily compensated for, the procedure is mentioned above*) ........

I will keep this in mind.

 

[Matthew Morgan J]

Lightbulb/Resistor explanations , Web Based tone generator, good stuff

Thanks again for a comprehensive reply, MMJ!

.

You are very welcome Mattcalf

In our previous chat you mentioned connecting a lightbulb in series to the woofer, where and what value resister would I need in this test circuit?

That is correct , a small lightbulb (like a mini hobby bulb) in series with the driver will do the trick , it will shine brightest right at the cabinet's tuning ....You would just want to run your signal generator up and down in frequency by 10hz above and below your target tuning while keeping an eye on your bulb to see at which frequency it becomes brightest............................In this sort of setup you can also take a voltmeter (in A/C mode, low voltage) and connect it across the lightbulb to see the changes in more detail .... The higher the voltage reading you are getting on your meter means the closer you are to the current cabinet tuning as you adjust the frequency on your signal generator .... (in this case you can even just replace the lightbulb with a 10 ohm resistor and pay attention solely to the voltmeter as you sweep your signal generator back and forth slowly through the general bass range in question)..


NOTE: If you don't already have a signal generator (to drive your amp in the above tuning and experiments) then I wanted you to know that there are some software signal generators out there , and i was even able to find a really cool and totally free web based signal generator! Go to the link , this is really cool , i think you will like it ..

Online Tone Generator - generate pure tones of any frequency

My tuning process was going to be as follows:

• Cut aperture E arc into baffle
• Ratchet strap/clamp baffle to box
• Run test circuit at 30Hz
• Slide the baffle up or down until the bulb is brightest/volt meter reads highest

.

You have the right idea here by using the clamps to allow you to easily swap out the front panel to experiment with the aperture shape (just make sure to clamp it well enough so there are no leaks)..... ...I do highly recommend experimenting with different aperture shapes and styles for fun and learning if you have the time to tinker with it (but i also know that some folks don't have that kind of spare time for such fiddling, and in that case "E" should suffice) .......

. Keep in mind that the aperture not only effects tuning but also the quality of resonance and amount of resonance .....

It would be easiest to run the tone/frequency up and down on the cabinet to perform your measurement in order to determine the tuning (Fb), i would do this first with the front panel installed and aperture "E" arc mounted right at the top of the driver as shown in the sketch (and as seen in my most recent photos of the Karlflex prototype box) .........

STRATEGIES:
If you see that the tuning is too low for your tastes i would recommend pulling the woofer out and trimming the end of the internal duct extension, or applying a hole saw to it (that would be the preferable method rather than raising the aperture arc) ...

If you discover that the tuning is initially too high then you can lower the aperture's arc to shade the top of the driver somewhat, this will shift the tuning downward by extending the path length (Fb) ...

Attempting to tune this cabinet below 30hz will be counterproductive, so i would consider 30hz to be the lowest i would go with it ..... It is a matter of finding a happy balance as bass "extension" is traded for bass "presence" ....................... With my light 12" PA driver I had to tune much higher to develop enough bass presence to keep up with it's midrange output, but of course your Lab15-4 is an entirely different sort of beast

 

[mattcalf]

Just a quick post to check in: got the cabinet together today, tuned to 33hz (no real reason why, I do like Larry Bird though). Doing the final glue up at the moment, will fill gaps and sand tomorrow and begin with my finish.

I'm going to stain the aperture and finish it gloss and use chalkboard paint on the rest of the cabinet. I know, bit wtf but hopefully it works!

I'll post finished pictures and video ASAP, but gotta leg it now to get ready for the mighty Swans vs Demons!

 

[Matthew Morgan J]

JOYOUS OCCASION! =D

Just a quick post to check in: got the cabinet together today, tuned to 33hz (no real reason why, I do like Larry Bird though). Doing the final glue up at the moment, will fill gaps and sand tomorrow and begin with my finish.

I'm going to stain the aperture and finish it gloss and use chalkboard paint on the rest of the cabinet. I know, bit wtf but hopefully it works!

Mattcalf,
EXCITING STUFF!!
Congrats on your new build!

If you don't mind i have a few questions:

Where did the tuning land when you first fired her up with Aperture "E"?

Did you find that it was easy enough to determine the tuning (Fb) with the resistor and A/C voltmeter method?

Did you have a chance to play any music over it and if so what did you think of the sound? and what did you neighbors think of the sound? Hahahaha

I'll post finished pictures and video ASAP, but gotta leg it now to get ready for the mighty Swans vs Demons!

I am very much looking forward to the photos and video! Swans vs Demons must be a football thing? Enjoy!

 

[mattcalf]

Mattcalf,
EXCITING STUFF!!
Congrats on your new build!

Thanks, I'm excited to get it finished off too!

Did you find that it was easy enough to determine the tuning (Fb) with the resistor and A/C voltmeter method?

It was terribly difficult until I found out I was using a 10k ohm resistor instead of a 10ohm resistor. After that it got a lot easier.

Where did the tuning land when you first fired her up with Aperture "E"?

I must be honest, I'm limited for time on the build and had a few mishaps today: used the wrong resistor, broke the thread on my speakon cable etc. So when I attached the aperture in a rough approximation of what I thought E should be and I measured it, it came out at 33hz and it was so late in the day that I was happy with that.

Did you have a chance to play any music over it and if so what did you think of the sound? and what did you neighbors think of the sound? Hahahaha

I got to play a few snippets of music before I tuned it, got the cabinet sealed, figured out the pre/power amp crossover and bridged the amplifier (more power). Two words for now: huge and controlled.

Attached is a photo of my test paint/stain.

 

[freddi]

exciting build - mattcalf - what's the approximate internal volume of your Karlflex ? I'd like to sometime try one with a traditional K-aperture but traditional K had a frontal aspect that allowed the aperture to barely "shade" the cone diameter as with this vintage Karlson "Eight" loaded with FE206EN. With a rising top end driver I might be able to get away with aperture "A" or MMJ's "Flask"

 

[freddi]

could there be such a variant as a "Kick-Karlflex" form tuned higher with higher gain in the hit region ? If so - would have any advantage whatsoever over other type? ( Regular K are kinda tuned that way )

140g mms B&C woofer in small Karlfles vs EV15L in littke Kalrson-Acoustic 115BK

115bk were ~19" inside width and had radial arc aperture - -Fb ~53Hz

115bk - EVM15L - mic on the ground - cabinet upright vs baffle "upright" - this cabinet sounded
real good on guitar

 

[Matthew Morgan J]

Oh! Such suspense! I patiently await any further feedback or data =)

It was terribly difficult until I found out I was using a 10k ohm resistor instead of a 10ohm resistor. After that it got a lot easier.

Hehe , that makes a big difference!

I must be honest, I'm limited for time on the build and had a few mishaps today: used the wrong resistor, broke the thread on my speakon cable etc. So when I attached the aperture in a rough approximation of what I thought E should be and I measured it, it came out at 33hz and it was so late in the day that I was happy with that.

33hz should be a good all around multipurpose tuning for both movies and music

I got to play a few snippets of music before I tuned it, got the cabinet sealed, figured out the pre/power amp crossover and bridged the amplifier (more power). Two words for now: huge and controlled.

Attached is a photo of my test paint/stain.

That sounds promising!

I am very much looking forward to any more reports, images or videos that you have for this build

 

[Matthew Morgan J]

I love this idea Freddi

could there be such a variant as a "Kick-Karlflex" form tuned higher with higher gain in the hit region ? If so - would have any advantage whatsoever over other type? ( Regular K are kinda tuned that way )

Freddi ,
I think that a "Kick-Karlflex" is a marvelous idea! Perhaps tuned somewhere between 60hz to 80hz .......

Using quarterwave loading we should be able to develop more resonance and gain as long as the cabinet isn't made too small ... Using quarterwave loading does come with it's own set of difficulties though, such as harmonic ripple and the cancellation hole etc but we can find ways to work around those issues just as we did with the low-tuned Karflex , in fact i fully expect that the higher tuning will make this less challenging to design and more fun!

If built i would expect a very lively sound, kicky and exciting with an abundance of midbass presence .. The only drawback being that a separate subwoofer cabinet would be required to fill in the lows for modern music playback, but that is a worthwhile trade-off for the increased efficiency , power handling , dynamics, presence and other benefits you gain when tuning your tops higher up

I would go with a series-tuned arrangment for drivers with typical motor force values , and possibly something parallel-tuned or hybrid, maybe like a SUPER PLANAR variant for use with drivers that have more capable motors .... I am contemplating an idea that would allow the usage of a K-slot with a parallel tuned 6th order alignments . .

 

[mattcalf]

Hi team,
Sorry for the gap between replies, I've been busy snowboarding of all things! Attached is a recent picture of the front, the sides and rear are a matte black chalkboard paint that hasn't seen any chalk yet but I'll keep you guys posted. I will post a video some time this week once all my neighbours go to work.

The sub sounds amazing, it's obviously effortless in its job, even at lower volumes and sounds great. It's not overpowering (which I was afraid of) but when I start turning the volume knob up it lets me know that it could induce a pneumothorax at any moment.

Thanks for the PM, MMJ, I figured I'd reply here incase anyone else was following along. My only question at this stage would be about crossover for the sub. Up to what frequency (<250hz) should I let the sub handle?

Freddi, the internal volume should be around 100L. I was also planning on utilising the K aperture but time was getting away from me.

 

[Matthew Morgan J]

WONDERFUL ! =D

Hi team,
Sorry for the gap between replies, I've been busy snowboarding of all things! Attached is a recent picture of the front, the sides and rear are a matte black chalkboard paint that hasn't seen any chalk yet but I'll keep you guys posted. I will post a video some time this week once all my neighbours go to work.

The sub sounds amazing, it's obviously effortless in its job, even at lower volumes and sounds great. It's not overpowering (which I was afraid of) but when I start turning the volume knob up it lets me know that it could induce a pneumothorax at any moment.

Mattcalf,

Your Karlflex cabinet looks great!

With the "E" style aperture lowered slightly (and shading just the top of the driver) it gives you a very cool aesthetic appeal I like it a lot , and it should be technically solid with enough well controlled resonance down low to give you some great subbass presence for such a compact cabinet ..

I also really like the finish that you used .... Very attractive .... That ended up working out well

Thanks for the PM, MMJ, I figured I'd reply here incase anyone else was following along. My only question at this stage would be about crossover for the sub. Up to what frequency (<250hz) should I let the sub handle?

I appreciate that you posted this publicly, so folks can see how things turned out ......

As far as the crossover is concerned that Lab15-4 driver was really meant to be used strictly for bass reproduction and according to it's published graph it is not that great above 150hz so we know it is good up to that point at least (as the Karlflex design itself was meant to have a very wide bandwidth which means that the cabinet will not the limiting factor here) , but i have to admit that I am curious about how high up in frequency it will play reliably when loaded with that driver (not that you would actually want to use it up that high for regular listening, unless you had a stereo set of them perhaps) ...

 

[gkh]

Hi guys,

now it's time for me to build a Karlflex 15, to be equipped with a Thomann speaker.

Here's my first drawing, all dimensions converted to metric:



Braces and stuffing / lining omitted on purpose, will add later. Comments and criticism is welcome!

 

[Matthew Morgan J]

=D

Hi guys,

now it's time for me to build a Karlflex 15, to be equipped with a Thomann speaker.

Here's my first drawing, all dimensions converted to metric:

View attachment 628790

Braces and stuffing / lining omitted on purpose, will add later. Comments and criticism is welcome!

Gkh ,
You definitely have the right idea with this panel sketch

The driver that you will want for the Karlflex is a different model though , the 15LB100 is the one to go with because it has enough motor force to work well in this compact cabinet

 

[gkh]

Gkh ,
You definitely have the right idea with this panel sketch

The driver that you will want for the Karlflex is a different model though , the 15LB100 is the one to go with because it has enough motor force to work well in this compact cabinet

Thank you
It was the speaker I wanted to link, but, you know, during the first coffee such things can happen

Edit:
Do you know the mounting hole diameter? Annoyingly enough, it's not on the data sheet

 

[Matthew Morgan J]

Lets get into contact with Sebastian

Thank you
It was the speaker I wanted to link, but, you know, during the first coffee such things can happen

Hehe ,
GOOD MORNING AGAIN! Such timing ... Speaker design has become our morning routine i guess

Edit:
Do you know the mounting hole diameter? Annoyingly enough, it's not on the data sheet

I think Sebastian still has one of his 15LB100 drivers just hanging around unused (not loaded into a cabinet yet), or at least that was the case when i talked to him about those drivers recently, so he should be able to get the measurements that you need from that one ..

I will notify him about this post ..

 

[gkh]

Hehe ,
GOOD MORNING AGAIN! Such timing ... Speaker design has become our morning routine i guess

The (early) morning is my most creative time - so it's definitely the best time for speaker design

I think Sebastian still has one of his 15LB100 drivers just hanging around unused (not loaded into a cabinet yet), or at least that was the case when i talked to him about those drivers recently, so he should be able to get the measurements that you need from that one ..

I will notify him about this post ..

Thanks, I'm looking forward to his reply!

 

[schlager]

Hi gkh, the mounting hole is 7 x 9 mm. Looking forward to hear how The Box is doing in the next Karlflex build

View attachment 166844_specification.doc

 

[gkh]

Having MMJ's approval and a few cups of coffee later, added bracing, stuffing etc:



I really hope that putting the box on 2" wheels wouldn't affect it's FR too much?

 

[USRFobiwan]

Does this design have 3 different tunings, or do I look at it the wrong way?