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Old 12th July 2008, 08:18 AM   #1
pp173 is offline pp173  United States
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Default Help with HiVi F8 Project

This is my first post, and I'd like to start out by saying I'm a complete novice - but I've wanted to try some kind of speaker project for 20 years. This started by trying to find decent replacement drivers for a pair of Mission speakers I had...

I came across a program called WinISD. I enterd the dimension of my enclosure and port and tried plugging in various speakers from the Parts Express catalog to see how they might perform. HiVi F8's seemed to be pretty flat and within my price range.

I was pleased with the replacement - they far outperformed the original 8" drivers. The low end get much deeper and better defined.

I thought the cabinets may have been a limiting factor to the efficiency of the drivers. And, some frequencies around 100-300hz were distorted at times. I was able to live with that... But, then the particle board backs of the cabinets started pushing past their retaining screw heads! What a racket!

So, I read a little (and probably far too little), and I decide to build my own cabinet. I also chose Morel MDT-20 tweeters (not sure now if that was a great choice) and Dayton 2Khz crossovers - both from Parts Express.

Here's where I get into trouble...

When I go to put HiVi's recommended box volume of 35 liters into WinISD, I noticed there was an option to show the driver parameters from their database. I noticed the parameters were different that what HiVi posted on their website. I decided to go with HiVi's values.

The recommended enclosure size still only came to a little over 30 liters. But, I decided to go with the 35 liter enclosure anyway. I used 3/4 MDF and built a pair of rough boxes for testing. They sounded TERRIBLE!

I then built enclosures based on the 30 liter design the HiVi specs yeilded in WinISD. The result sounded better - but still far, far worse than when the speakers were mounted in the Mission cabinets (which were about 19 liters).

So, it seemed like the values in the WinISD database must be MUCH closer to what the actual specifications of the driver are. But, so far I've found 3 different sets of specs for this driver (HiVi's website, Parts Express's website, and WinISD). With that much disparity, how would I even know if WinISD is correct?

Also, I'm not sure how to take into account the volume of the driver in the enclosure. HiVi doesn't publish the driver volume, and I'm I wouldn't think you could really use a rule of thumb. It would explain the descrepency in enclosure sizes (if it took up about 15 liters) - but it still wouldn't explain the different specifications.

The current state of things is this:
My enclosure is 14.5w x 16h x 8d (external). WinISD called for a 10.25" x 3" port to tune to its' recommended 45hz. I found through experimentation that I like the sound of a 13" x 3" tube better. Due to the limitations of the enclosure size, the tube exits the top. I don't have dampening material on the sides of the enclosure yet - I'm still trying to figure out if I'm going to need to build another one!

The tweeter is installed with an adjustable 100w lpad, which seems to sound best half open.

The mid-range is quite harsh to my ears, and - though, as a whole, it outperforms the Mission experiment - the bottom still sounds like the enclosure isn't correct.

There's also noticeable distortion in the 1200-2200hz range. I'm not experienced enough to know if this is due to my lack of dampening material, a poor enclosure design, poor choice of a crossover point, or all of the above (and then some).

You read through the posts, and the first thing you pick up is that the advice to newbies is to build an existing design!

I've been using a DSP card in my PC to perform some parametric EQ functions, as I don't have a good EQ. And, BTW, these are being driven by a Kenwood KA880D integrated amp. I needed a fair bit of correction to get them to sound pleasing. I can post where and how much if it would help solve my problem.

With my limited experience, the best I could figure is that I need to build a better enclosure (requiring the proper specs), lower my crossover point to give the woofer a better shot at doing what it does well, and find a tweeter with extended response in the low end.

Any thoughts are greatly appreciated!

Peter
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Old 12th July 2008, 08:03 PM   #2
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Join Date: May 2006
Do yourself a favor and buy a woofer tester II or III from
Parts express. Very acurate mesurements with it.
I no longer rely on manufacturer's specs ( used HI-VI' s a couple
of times, excellent drivers for the money) but very unreliable specs.
The woofer tester is a good investement!.
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Old 12th July 2008, 08:28 PM   #3
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Location: Central Florida
Peter,
You've chosen a difficult path for learning loudspeaker design, but not an impossible one.
First and foremost, find a book on the subject that explains the golden ratio for cab dimensions and also rudimentary xover designs. As you read it you will understand what is happening in your cab. The cab volume is not the problem, it's the stackup of resonant frequencies and the lack of damping that you're hearing.
Dont give up, you'll work it out.
Bill
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Old 12th July 2008, 10:23 PM   #4
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Default Re: Help with HiVi F8 Project

Quote:
Originally posted by pp173
[B]This is my first post, and I'd like to start out by saying I'm a complete novice - but I've wanted to try some kind of speaker project for 20 years. This started by trying to find decent replacement drivers for a pair of Mission speakers I had...

I came across a program called WinISD. I enterd the dimension of my enclosure and port and tried plugging in various speakers from the Parts Express catalog to see how they might perform. HiVi F8's seemed to be pretty flat and within my price range.

I was pleased with the replacement - they far outperformed the original 8" drivers. The low end get much deeper and better defined.
Well they are far better drivers than what Mission used in most of its speakers, Hi-Vi are used even by ultra high-end commercial speakers. Many Hi-Vi drivers are inspired by famous high-end European drivers (Dynaudio and Focal) but they're the opposite of cheap knock-offs: in many cases Hi-Vi has actually improved on the original design which explains why they measure differently. Like all "F" drivers from Hi-Vi the F8 is derived from a Focal driver, quite a prestigious pedigree. Low price is due to Hi-Vi being a Chinese firm but don't let that fool you, there are audiophiles in China who know darn well what it takes to make a high-end driver.

That said dropping a Hi-Vi or any "foreign" driver in a system originally designed for a different driver is often an endeavor fraught with frustration: the new driver will likely be poorly matched with the crossover and/or cabinet, or both.

Quote:
I thought the cabinets may have been a limiting factor to the efficiency of the drivers. And, some frequencies around 100-300hz were distorted at times. I was able to live with that...
Were the new drivers broken in when you noticed that?

Quote:
But, then the particle board backs of the cabinets started pushing past their retaining screw heads! What a racket!
Wow, new drivers blowing off cabinet panels is not something you hear about often lol

But then screwed on panels is a rare occurrence in hi-fi speakers.

Quote:
You read through the posts, and the first thing you pick up is that the advice to newbies is to build an existing design!
That's to build up self-confidence and give you the satisfaction of producing a nice sounding speaker on your first attempt. You can then listen to those speakers while working on your own design(s) which usually takes a long time.

Quote:
With my limited experience, the best I could figure is that I need to build a better enclosure (requiring the proper specs), lower my crossover point to give the woofer a better shot at doing what it does well, and find a tweeter with extended response in the low end.
Or use a steeper slope. An electronic Xover would be very useful to determine if various types of Xovers would iron out the problems without actually having to build them, which is costly. A professional grade electronic crossover such as the Behringer Ultradrive Pro DCX2496 is a must-have tool for any speaker designer. It costs about $330 which is less than you would have to invest on Xover parts if you were to test many different configurations. You use the Behringer to determine slope, type and crossover frequency that yield the best results then build a passive crossover based on those results.
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Old 12th July 2008, 11:48 PM   #5
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Quote:
When I go to put HiVi's recommended box volume of 35 liters into WinISD
I just pulled up the F8 spec sheet, it said recommended box volume was 19L with a tuning frequency of 40 hz.
Are you using one woofer per box?

Anyway, you really need a custom crossover. I've never had a crossover built with formula result values work.

JJ
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Old 14th July 2008, 02:33 AM   #6
pp173 is offline pp173  United States
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Join Date: Jul 2008
I want to thank everyone for helping me!

Turboyam, I just ordered the woofer tester 3. At $100, I've actually spent as much on MDF while experimenting! It seems like a wise purchase. I have to think the most important starting point is accurate specifications.

Bill Fuss, I've done some reading on the golden ratio. When I have my new specs, I'll be making sure I build according to the ratio. I was thinking about starting to use Winspeakerz - does it automatically output dimensions in the golden ratio?

Willitwork, the drivers were broken in when the 100-300hz range was "weird. And, yeah, I was also lauging when I found the source of my rattle was the back covers on the cabinets. But, I have to think part of it was the joy of knowing I didn't blow my woofers! I don't think I'll be ponying up the cash for the external crossover. But, I have begun some reading on deciding and constructing.

Jupiterjune, I went back to the Swan Speaker website to make sure I was looking at the right specs. It still gives me 35L. Are you going to this link?:
http://www.swanspeaker.com/product/htm/view.asp?id=74

Thanks everone for getting me off on a good start. Does anyone know what the volume I have to add to the cabinet for the F8 is?

Thanks again,
Peter
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Old 14th July 2008, 09:13 AM   #7
sreten is offline sreten  United Kingdom
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Location: Brighton UK
Hmmm......

Clueless. And building cabinets is a poor way to develop speakers.
FWIW the 19L boxes are too small but probably sound somewhat
more balanced (but poor bass) due to the underdamped bass
alignment giving you some BSC (baffle step compensation).

PE off the shelf crossovers are a joke, to be bought by the inept.
Golden ratios and rudimentary c/o design is a waste of time.
Rudimentary = wrong.

Peruse these sites until it starts to make some sense :

http://www.zaphaudio.com/
http://www.rjbaudio.com/projects.html
http://www.troelsgravesen.dk/Diy_Lou...r_Projects.htm
http://www.humblehomemadehifi.com/
http://htguide.com/forum/forumdisplay.php4?f=39

http://www.rjbaudio.com/Audiofiles/FRDtools.html
http://www.geocities.com/woove99/Spkrbldg/


/sreten.
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Old 14th July 2008, 05:36 PM   #8
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Join Date: Jun 2007
The Golden Ratio is about visually appealing cabinets, not necessarily about sound, unless I have the wrong Golden Rule.

"The width is, therefore, 1.414 times the height and the height is 1.414 times the depth." (Badmaieff/Davis)

In this case, the person is describing a bookshelf speaker laying on its side. width being the longest dimension, height the second longest, and the depth being the shorted.

Put another way, your dimension ratios should be like this

1.414 to 1.000 to 0.707 (H to W to D) [Height being the longest dimension)

So, assuming our bookshelf speakers are now standing on the small end. If the width is 10 inches, then the height is 14.14 inches, and the depth is 7.07 inches.

14.14" x 10.00" x 7.07"


So, pick a width, say for illustration, 12".

Then the longest dimension, which I will call the height, is -

12" x 1.414 = 16.968".

The shortest dimension, the depth, is then -

12" x 0.707 = 8.484".

17" x 12" x 8.5 " = 1734 Cu.In or 1734/1728 = 1.00347 Cu.Ft.

Converted to Liters, about 28.3L.

Or is there another 'Golden Rule'?

Now people certainly don't follow this absolutely. Towers aren't built on these ratios. But you do want to stay away from multiples of the same number.

30" x 20" x 10" is too many multiples of 10.

36" x 18" x 12" is too many multiples of 12.

For what little I can add.

Steve/bluewizard
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Old 14th July 2008, 06:30 PM   #9
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Quote:
Originally posted by pp173
I don't think I'll be ponying up the cash for the external crossover. But, I have begun some reading on deciding and constructing.
Just to be clear, I didn't mean for you to use the active Xover as a permanent part of the speaker only as a design aid. It's not worth the expense if you only intend to build a single design unless it's a high-end set.
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Old 14th July 2008, 11:30 PM   #10
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Quote:
Jupiterjune, I went back to the Swan Speaker website to make sure I was looking at the right specs. It still gives me 35L. Are you going to this link?:
No, I got it off the spec. sheet posted under product information at Parts Express. I guess the woofer tester is your best investment -- it will be the surest way to know you are designing with the correct parameters.

I have Xover pro from Harristech. The specs are preloaded into it (the old ones though). I could post simple 2nd order crossover values for you to try. (I already simm'ed it, but with what are likely the wrong values.)


JJ
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