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Old 12th January 2010, 12:57 PM   #61
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Old 16th January 2010, 06:59 AM   #62
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Default latest proto

Thank goodness the Qts is now lower! 0,8 i suspect would be ok for a sealed design, but with that Vas and Qts a BR would be huge. so 2 Qts versions as you state may indeed be a flexible option to DIYers, though with an MMS of 12g im not all that sure that youd be offering a 'lighter' option than many of the other 'budget' drivers:

http://www.hautparleur.fr/_audax/ap170m0.jpg

just for reference, (it was a 6" driver wasnt it?)

http://www.hautparleur.fr/_audax/ap210m0.jpg

and again for reference, in case it was an 8"

given that these drivers are now obsolete, and were never perfect, if there is such a thing. They did however, fit into a 'budget' system and were easy to implement with minimal crossover componenets. This is something i can see you are trying to achieve with these non-FR drivers, and is the reason i am interested, and was using the Audax drivers at the time.

As for the tweeter, im not sure why all that talk of extending FR to 30kHz...I know i can hear to about 17kHz, and possibly the effects of unheard harmonics out of hearing range may influence the audible sound, but is it really necessary?

Someone once said to me, in regard to FR:

'if i can reproduce 100Hz to 15kHz, within +/- 1 dB; rather than 50Hz to 30kHz +/- 3dB, which should i do?'

in respect to tweeter OR FR, if the Mms is more than, um, 5grammes; transient response of HF is going to be awful anyway, within a stiff cone. Even using breakup to extend HF isnt going to improve that hugely i shouldnt think, 'searchlight' HF being the compromise
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Last edited by mondogenerator; 16th January 2010 at 07:05 AM.
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Old 16th January 2010, 07:11 AM   #63
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Quote:
Originally Posted by human.bin View Post
manies open bafflers would like an affordable tweeter that can handle without struggle a low xo point like the around 1250 of Linkwitz's Orion...
I dont do OB's but i have to agree. Id prefer the tweeter to give up the extension to 30kHz and instead extend downward to say 300-500Hz easily, a la the 2" cone tweeters of old, albeit with the technology of today

even maybe a inverted dome 2"?

Oh and the black cone is good, but i have to say the white one gives it that "80's studio monitor" look. I dont see why that doesnt appeal to everyone!!!
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Old 16th January 2010, 07:24 AM   #64
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Default another aside...bear with me mark :p

just out of interest this is the tweeter im currently using:

http://www.visaton.com/bilder/freque...g20sc_8_fs.gif

whilst the FR isnt perfect it seems to be within +/- 2dB, and for most of its range less deviation than that, it wasnt really budget i guess at about 25 GBP, but im my experience, at any less than that you get less performance.

I have tired of cheaper tweeters that LOOK smooth but sound harsh still. The G20sc is smooth as silk and has a great value: performance ratio, in my opinion.

I have tried many Audax tweeters, which at the time were fairly highly regarded, and i was never satisfied with the outcome. One exception was a 30mm Audax softdome(cant think of the name), this went from about 800Hz to 16KHz(just!) and did so very cleanly.

If there was one thing the G20sc driver should do better it would have a lower Fs so it was easier to implement with lower crossover points.

EDIT: found the 34mm tweeter....on axis isnt perfect, and certainly NOT flat to 30K, but it sounded great, wish i had kept them

http://www.hautparleur.fr/_audax/tw037y0b.jpg
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Last edited by mondogenerator; 16th January 2010 at 07:30 AM.
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Old 16th January 2010, 10:33 PM   #65
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Quote:
Originally Posted by mondogenerator View Post
Thank goodness the Qts is now lower! 0,8 i suspect would be ok for a sealed design, but with that Vas and Qts a BR would be huge. so 2 Qts versions as you state may indeed be a flexible option to DIYers, though with an MMS of 12g im not all that sure that youd be offering a 'lighter' option than many of the other 'budget' drivers:

http://www.hautparleur.fr/_audax/ap170m0.jpg

just for reference, (it was a 6" driver wasnt it?)
Hello Mondogenerator,
You've raised many interesting comments but you may have fallen into a couple of sand-traps by being overly selective when interpreting driver data and in the case of tweeters, assuming the data shown by those makers hasn't been smoothed.

Let's start with my Woofer:
Agreed, my latest pre-production samples (black cone) will be more versatile and user friendly. Interesting you're quoting the Audax AP170. As I've said many times, I'm more than reluctant to specifically comment on performance merits of a competitors product. So you'll understand that I'll discuss these topics in more general terms.

I researched many woofers some time back, most had moving masses above 12g. Most values appear in the 15g to 18g area because the designer is striking a balance between various performance features.

Much depends on what folks want from a woofer. Low MMS will result in a "trade off" somewhere else in the driver's performance envelope. Usually, the outcome is the raising of a driver's Fo, typically in woofers this size from the low 40's up to near 60Hz. Shorter Xmax, power handling and distortion may also be an issue for some drivers that follow this design rout. Many light coned-low mass drivers maybe be more efficient and therefore easier to drive. So they're likely to be found on lower powered systems where issues of power handling aren't so challenging. Bear in mind that most woofers usually find a home on systems where power is more plentiful so MMS and Xmax can be features to consider at when selecting drivers to suit amplification output.

I'm well known for "stretching" the performance envelope in Full Range but I have to face commercial reality with a driver of this sort. It's a very different world from Full Range. Low Fo, wider Xmax and flat response to near 5-kHz, power handling and lower cost are features that most audio folks look for in a woofer. To date, this thread has generated 77 emails enquires to me. All these communications talk about the features I've mentioned, hence my latest effort with the black cone prototypes.

There's always a compromise to be struck whenever a driver is designed and made. You're correct in the "less than" perfect. This of course applies to all human activity.

I'll deal with Tweets in another post.

Cheers

Mark.

Last edited by markaudio; 17th January 2010 at 03:35 AM. Reason: Typo mending
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Old 17th January 2010, 02:43 AM   #66
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Hello again Modongenerator

Re the matter of Tweets, sadly some makers, shall we say "massage" their graphic illustrations. I've always felt uncomfortable following suit. In the early days of Markaudio, I was hammered by a few on this forum for producing RAW data. They failed to observe the differences between RAW and smoothed data when making their comparisons. As a result, I had to follow much of the rest of the driver industry and smooth. I'm now able to produce more RAW data again as more audio guys become aware of the differences.

Having looked at some of the examples you mention, I urge you and anyone else reading this post to take more time when interpreting and comparing published data. Please don't automatically assume that a frequency range is near flat. It may not be the case in reality and may explain some of your dissatisfaction with some tweets. Interestingly, I'm finding a greater acceptance for drivers with more variable range response. Scott's comments on the Alpair 12 illustrate my work in this area:

Initial Impressions: Alpair 12 full-range driver by Mark Fenlon

Onto the subject of a Tweets range. Again its a question of commercial reality. There's allot of low priced Tweets tracking to 20-kHz so there's no point in me reproducing the same. My Tweeter No. 3, as its now named has already received favourable feedback in beta testing in Canada. Have I got the performance V price mix right? Only time will tell. But of this I'm sure, I had to offer more HF performance with this tweeter to make it attractive to the majority of prospective buyers. Since my 6.5" woof's looking good to around 5-kHz, the cross points are in the region of 2 to 4.5-kHz. Frankly speaking, I personally wouldn't rely on any small tweet to handle low extension, there's just too many technical and acoustic problems.

Now when it comes to making a wide 2" unit, now you're heading more into territory that for me feels comfortable. The issue of lower extension comes is more technically achievable and goes part of way to explaining my efforts with the 2" proto.

Cheers

Mark.

Last edited by markaudio; 17th January 2010 at 03:46 AM. Reason: typo mending
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Old 17th January 2010, 02:36 PM   #67
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i take all you have mentioned in good stead. In my experience, most manufacturers smooth their FR curves, fact of life. The fact you do not bodes well and would tempt criticism from those that do not know this. Also Mms on the Audax drivers are after all a standard deviation, and i dont think these numbers were EVER changed or updated on a batch basis. This is unlike the visatons im using. The net result of this was that the specs on drivers were actally quite a long way out, back when i purcahsed drivers. In the viatons case this is not so, and i thus have more confidence in them. In no way would i say that they were better than your drivers or worse. They were very light paper cones and also used godawful foam surrounds, which although may have supporters, I personally cannot stand. Their one advantage i guess is their comparative lightness compared with neoprene. I dont exactly know what material you use for surrounds but from appearances at least, it appears to be a far more robust offering, even if it is thinner.

So as you said, compromises have to be made.

The drivers ilinked were shown, mainly just to illustrate that there are drivers with a lower MMS out there, whether this is good or not. And also, although i know you cannot comment on this, I believe that these are drivers which COULD have been so much better, but started with what i believe are common goals to your own.

As my father worked on the goodmans version of the LS3/5a, and further research and protos after the aquisition of the contract, i understand the change in driver philosphies over the years. I also understand the compromises. What were in reality, theoretically poor drivers(bad bad bextrene, high Mms, low eff.), actually sound very good, even to this day, and are rarely bettered by many commercial products under 1000/pair, perhaps more.

It is though, a totallly different school of design, to your own. albeit with different limitations. This is what brought me into DIY in the first place. At an early stage i wanted to build something of the ilk of the LS3, however now i believe lighter, more WB is the way to go. Whether it be FR or a WB 2 way.

dont take any of my comments as a critique of your designs, it isnot. merely thinking where other designers/manufacturers have gone alittle awry, maybe you could accomplish something new. Rather like you have already in the FR world...It wouldnt be the first time ive said that im not into the whole fostex fanclub thing, they sound too 'old' and tuned to me, even if they are good transiently.

so anyway good luck
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Old 17th January 2010, 06:15 PM   #68
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Quote:
Originally Posted by mondogenerator View Post
dont take any of my comments as a critique of your designs, it isnot. merely thinking where other designers/manufacturers have gone alittle awry, maybe you could accomplish something new. Rather like you have already in the FR world...It wouldnt be the first time ive said that im not into the whole fostex fanclub thing, they sound too 'old' and tuned to me, even if they are good transiently.

so anyway good luck
Hello Mondogenerator,
Thanks for this reply. I've found your comments refreshing, understand your sentiments and have similar feelings on much of much of your thinking. Making a woof is a new challenge for me. In some ways, working on Full Range is easier because the goals are clearer. Mostly, it's about extending the usable frequency in an FR driver. It gets a bit more complex for woofers because of the wide variety of customer needs. This shows up in the wide variation on the specs for 6.5" woofers.
For my part, having listened to what folks have been saying on this thread, I've concentrated on near flat response to make it easier to cross; And getting the driver to deliver set of T/S for easier cab designs. I've kept the cone light so I'm able to make it micro-resonate. Last but not least is cost. I had to juggle between my natural instinct to up-grade while recognising that it's economically tough for most folks at this time. So doing my bit to produce a lower cost unit is also important.

Cheers

Mark.
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Old 18th January 2010, 10:12 PM   #69
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Hi Guys,
There could be an interesting discussion developing on the limits of human hearing. This subject was raised by forum member Tresch in relation to my work on Tweeter No.3. This emitter has extended output to 30-kHz.

Post contributions to this issue have been moved to a new dedicated thread. New contributions to this subject can now be made on this thread:

Upper Limits of Human Hearing

Many thanks

Mark.

Last edited by markaudio; 18th January 2010 at 10:14 PM.
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Old 18th January 2010, 10:17 PM   #70
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ok Mark send each member in the discussion a free demo pair so that we can run test under control ...no... really what's the price? i can't see it on the website
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