A TL for the A7

[Bob Brines]

I have just completed a 36" folded TL for the A7 that is only 17" tall. I will be introducing it on the full range forum once I get my stuff in one basket. This is my first real attempt at a speaker with a driver smaller than 6" nominal and I am impressed. Excluding a few spikes, it's pretty much flat 80-8K. Even a bit of BBC dip that I like. With a bit of bass boost, it's even usable down to near the 40Hz I require for a successful single driver design. As such, they will be best suited for computer speakers or small bedroom speakers if any real volume is required. I am using the now in 15'x24' room in my standard 8' triangle and I find them adequately loud for my favorite baroque orchestra or a girl-and-a-guitar.

I put these speaker on my HT and ran them as "large" and found the bass lacking (go figure!). However, using the HT DSP crossover to a rather nice 10" sub of my own design at 160Hz, the results are stunning. Maybe it's just that my ears are too old and beat up to here it, but I don't find that the A7's are particularly unforgiving to less than kilo buck equipment. The handled the regular TV and Blueray stuff very well, even the Sirius Radio that streams through Dish Network. Sure, not as good by a mile compared to 24/96 files straight from my PC, but very listenable.

My problem with the A7's is the ringing above 8K, particularly the twin peaks at ~12K and 16K. This starts to ramp up at ~8K. While the A7 is not particualr sibilant, it is definitely edgy. I can easily EQ this out with DSP. but it may be a problem passively.

Any thoughts?

Bob

[markaudio]

Originally Posted by Bob Brines

I have just completed a 36" folded TL for the A7 that is only 17" tall. I will be introducing it on the full range forum once I get my stuff in one basket. This is my first real attempt at a speaker with a driver smaller than 6" nominal and I am impressed. Excluding a few spikes, it's pretty much flat 80-8K. Even a bit of BBC dip that I like. With a bit of bass boost, it's even usable down to near the 40Hz I require for a successful single driver design. As such, they will be best suited for computer speakers or small bedroom speakers if any real volume is required. I am using the now in 15'x24' room in my standard 8' triangle and I find them adequately loud for my favorite baroque orchestra or a girl-and-a-guitar.

I put these speaker on my HT and ran them as "large" and found the bass lacking (go figure!). However, using the HT DSP crossover to a rather nice 10" sub of my own design at 160Hz, the results are stunning. Maybe it's just that my ears are too old and beat up to here it, but I don't find that the A7's are particularly unforgiving to less than kilo buck equipment. The handled the regular TV and Blueray stuff very well, even the Sirius Radio that streams through Dish Network. Sure, not as good by a mile compared to 24/96 files straight from my PC, but very listenable.

My problem with the A7's is the ringing above 8K, particularly the twin peaks at ~12K and 16K. This starts to ramp up at ~8K. While the A7 is not particualr sibilant, it is definitely edgy. I can easily EQ this out with DSP. but it may be a problem passively.
Any thoughts?
Bob

Hello Bob,
Your folded TL project sounds very interesting and thanks on advance for the time when you'll post more details on the forum. I'm already very curious to see pics of the project. Hoping you can post a plan?

I'm pleased to read that the Alp7's are doing what's expected. It's to the Alp7's credit, that with only a 70-mm diameter cone, your getting successful results inside a large room of 15' X 24'.

On the issue of partnering amps and source equipment, Alp7's usually require descent gear. There's several threads where I've said "make sure the up-stream part of the system is up to the task". Your right, it's not necessary to spend "Kilo-bucks". I've posted a pic of my home system using Tony's 300B. With 4 inputs, it runs the TV, DVD (Blue-ray), CD and Mac-Mini. I bought Tony's 300B with all its vintage goodies for US$700 while my CD player is an old Accuphase DP65 cost US$500 (from my memory). I've recently heard Alp7's on cheap EL34 China brand amps and an old Denon DCD CD payer, very impressive sound.

On the Alp7's higher range output, yes they can be "edgy" as you put it. This is an intentional part of their design. The Alp7 cone and power-train are very resonance to micro-resonance sensitive. This gives Diyers the opportunity to tune the project or system to suit their needs, optimise equipment partnering, experiment with on/off axis room positioning etc. I'm blessed with good hearing for a 53 year old. I've retained excellent audibility to 16-kHz while my hearing's pitch accuracy remains good. I run my 7's an home without any need for any equalisation. The imaging and detail from my Alp7 system is fab. My listening space is smaller than yours, so I'm likely not driving the Alp7's as hard as your set-up.

Take a look at the other project thread and posts on the Alp7 to read the about the successes other Diyers have achieved with the Alp7.

More important, your feedback comes at a good time. Perhaps this is right moment for me to announce the making of the next Generation of Alpair 7. More on this in the coming weeks.

Thanks

Mark.

[ultrakaz]

Originally Posted by markaudio

Hello Bob,
On the Alp7's higher range output, yes they are "edgy" as you put it. This is an intentional part of their design. Its cone and power-train are very resonance to micro-resonance sensitive. This gives Diyers the opportunity to tune the project or system to suit their needs, optimise equipment partnering, experiment with on/off axis room positioning etc. I'm blessed with good hearing for a 53 year old. I've retained excellent audibility to 16-kHz while my hearing's pitch accuracy remains good. I run my 7's an home without any need for any equalisation. The imaging and detail from my Alp7 system is fab. My listening space is smaller than yours, so I'm likely not driving the Alp7's as hard as your set-up.
Mark.

Mark, any chance of another version of the A7 without the rising top end? Some of us like a flatter on axis response. A 4" is going to start breaking up around 4kHz so if it possible through modern design to "damp" the cone/response or push it out further so that it is flat or even down a couple of dbs around 8kHz would appeal to another set of listeners. Most of us realize published sensitivity is different than what the efficiency is at a 100Hz or less; ie, 4" drivers of like composition have roughly the same sensitivity at 100Hz.

Also, it is not only how well you hear, but rather how sensitive one is to a particular frequency(s). For me any peak at around 7 or 8kHz kills me. I only offer this because you seem to be more open to feedback from us diyers.

Sorry if you already know all of this.

[markaudio]

Originally Posted by ultrakaz

Mark, any chance of another version of the A7 without the rising top end? Some of us like a flatter on axis response. A 4" is going to start breaking up around 4kHz so if it possible through modern design to "damp" the cone/response or push it out further so that it is flat or even down a couple of dbs around 8kHz would appeal to another set of listeners. Most of us realize published sensitivity is different than what the efficiency is at a 100Hz or less; ie, 4" drivers of like composition have roughly the same sensitivity at 100Hz.
Also, it is not only how well you hear, but rather how sensitive one is to a particular frequency(s). For me any peak at around 7 or 8kHz kills me. I only offer this because you seem to be more open to feedback from us diyers.
Sorry if you already know all of this.

Hi Ultrakaz,
This is where designing drivers becomes interesting but also challenging. Here's a recent comment from member Ra7 (direct quote):

"If the cone material doesn't have a good sound, a flat response can also sound quite lifeless."

The Alpair 6M and CHP-70 is favoured by those Diyers who want a more controlled response. Interestingly, I received some criticism recently for making the Alp6M's Mid-HF response, too restrictive.

I think the answer is for me to try making more driver variants. But this will cost more money and time. Being a small business, its a big challenge but I'll try my best.

Thanks

Mark.

[Bob Brines]

Mark,

Here are pictures of my A7 TL. I'm still collecting data, but what bothers me is the way the waterfall rings at the top. I understand you point, and I can easily EQ the down. Designer's choice, no?

Bob

Alpair 7 TL.jpg

Tl Interior.jpg

Waterfall.gif

[ultrakaz]

Originally Posted by markaudio

Hi Ultrakaz,
I think the answer is for me to try making more driver variants. But this will cost more money and time. Being a small business, its a big challenge but I'll try my best.
Mark.

Thanks for the response.

I've been messing around with full range (wide band) drivers for the last 10 years or so. I'd list them all but I've forgotten most of them. The ones that do stand out though as widebands are the ones that I initially thought were too dead sounding. Diatone 610mb, Altec 755c, Fostex 168eSigma first version, and even the Feastrex d10nf all sounded polite at first, but now I favor them for not imposing its own sound on the music. Sure, all could use more top end, but not at the expense of overall sound. And there are more edgy sounding drivers that sound "better" but only briefly on selected tracks before a group of listeners. However, in the end I'm the only one listening to it for hours on all types of music.

Yes, it is impossible to please everyone with one driver, so it would be great to see another variant of the A7.

[markaudio]

Hi Bob,
Nice looking build. Looking at the front baffle, how thick is the material? Did you manage to round-off or angle the inside of the driver cut-out? The thing that worries me a bit is the close proximity of the top of the internal baffle to the rear of the driver. I guess you've adding damping material to mitigate internal reflection.

Re "ringing at the top"? You've surprised me with this comment. With just over 7000 units in use, I'd have received allot of flack by now, if I were so far-off with this driver's design. Extended decay at this high F range is part of the performance extension to near 30-kHz. Looking at your waterfall, the Alp7 is doing what's expected with its 70-mm cone.

For those DIyers who desire a flatter response, Eq out or adjust using axis positioning. Those Diyers who favour more imaging and detail in the high ranges will keep this part of the drivers performance characteristics.

Its worth looking at MJ Magazine's (Japan) Alp12 test review and comparison to the Diatone's P610 and Diato's Voice DS-16, particularly the off-axis performance differences. The 12's better off-axis and lower distortion levels won many converts. Alpairs using Multi-form cones have a much wider dispersion as they allow for practical choice on the extension and use of high range.

Just goes to show thats its pretty much impossible to build a full-ranger to do everything and fit all expectations and tastes. Commercial considerations have to kick in. Yes, I can build drivers with flat responses but sales of drivers with rising responses are proving more appealing. Will I sell enough flat response units to pay the bills? I don't have the answer to this so glad of more feedback.

1- Make drivers that are easily tuned.
2 -Try to make more variants when resources permit.

Cheers

Mark.

[markaudio]

Hi Ultrakaz,

I've possibly answered some of your thinking in previous posts. If more Diyers come forward and sufficient numbers want me to make flatter-response units, I'm happy to do it.

But its a commercial risk and I went through this process 2+ years back where I got panned for making drivers too flat/resonance neutral.

If I had a ton of money, I've love to make more variety of drivers.

Thanks

Mark.

[_henry_]

mark,

is group buy possible for another version?

any chance on neo magnets?

cheers
henry

[markaudio]

Originally Posted by _henry_

mark,
is group buy possible for another version?
any chance on neo magnets?
cheers
henry

Absolutely, I welcome all help right now. The Japan situation has hit me quite hard. No complaints considering what many thousands of coastal folks are enduring.

Neo, possibly, but these magnets will likely push up the rising response even more. I think I'm already in enough hot water with Bob and Ulk as it is!

Thanks

Mark.