A novice project

[astute]

Hi all,

I have only recently discovered an interest in sound and hi fi. I have been researching speakers for home theatre and music use and have been reading reviews and trying to work out what I am looking for in a set of speakers. I have a nice plasma TV and have recently bought a solid mid-range AV Receiver (The Sony 5400ES).

Speakers are much more difficult to choose. After a lot of reading, I figured the best way to work out what I want is to get my feet wet and try out a few things. So, I took the super cheap ($15) option of buying a set of 4 little plastic Panasonic satellite speakers to help me answer the question "Do I really want the hassle of surround sound, or should I just stick with a good stereo setup?" That gave me enough to know that with the right movie, surround sound is fantastic and well worth investigating further.

So now, I really want to learn more about speakers and what makes good sound. I thought that the drivers in these panasonic speakers might make for a worthy low-cost "first build" project/experiment for a novice such as myself. To my inexperienced ear, these speakers have reasonable sound up high, but relatively poor midrange and bass.

So, my thought was: can I take the drivers from these little plastic speakers and build some cabinets that make them sound better? I have disassembled one of the speakers and come up with the following information:

- The speaker is a 2 way design with a volume I would estimate at somewhere between 1 and 1.5 litres. It has a small cylindrical port on the front as well
- The tweeter is about 5 cm in diameter and has 8 ohms printed on the back of it. It also has the "65PH513A2" printed on it (I think, the printing is difficult to read). A quick google for this didn't give me any hits
- The woofer is about 7 cm in diameter and also has 8 ohms printed on the back, as well as "G8P529B2". Unfortunately this didn't get me any hits in google either.
- The crossover seems to consist of a Richey 4.7uF50V capacitor wired to the tweeter.

I was wondering if anyone has any ideas on identifying these drivers? Does anybody think it would be a worthwhile project to build some cabinets for these? Would a nice MDF box of the appropriate volume enhance the frequency response, or are the woofers just too small to be worthwhile experimenting with?

Thanks to anybody who made it this far! Any suggestions or advice would be much appreciated

Cheers,
Michael.

[PeteMcK]

astute,

Info on Panasonics (Matsushita) is virtually impossible to find,
the only way without flying blind is to test them yourself:

ARTA http://www.fesb.hr/~mateljan/arta/download.htm
ARTA Jig - http://zobsky.blogspot.com/2008/01/s...t-jig-for.html

As to the speakers you have, you'll probably find that they do SOME of the spectrum well, but they'll have limitations (after all, they're from consumer product built to a price). It's fun to play with these, and they may well make good surround speakers,
a good first project, but for your mains, there's no substitute for quality drivers...

Once you have the parameters and an impedance curve, you can probably improve the existing performance with a better box and crossover, but I wouldn't expect the improvement to be dramatic, unless you are lucky, some Panasonic drivers are gems...

[Moondog55]

Welcome to an addiction.

I second Petes comment about fun, but I have never found the sound of any of those "HT in a Box" speakers to be worth long term listening.

If you give the forum members lots more information on what you expect from the project, your budget, what your room looks like and how big it is you may get much more information than you can cope with, but it will be worthwhile.

My limited experience says that the centre and the left and right speakers have to match, and anything smaller than a 5inch driver (135mm ) can't produce the volume (SPL) needed without distorting.

[ChrisA]

Originally posted by astute
Hi all,

I have only recently discovered an interest in sound and hi fi. I have been researching speakers for home theatre and music use and have been reading reviews and trying to work out what I am looking for in a set of speakers. I have a nice plasma TV and have recently bought a solid mid-range AV Receiver (The Sony 5400ES).

Speakers are much more difficult to choose. After a lot of reading, I figured the best way to work out what I want is to get my feet wet and try out a few things. So, I took the super cheap ($15) option of buying a set of 4 little plastic Panasonic satellite speakers to help me answer the question "Do I really want the hassle of surround sound, or should I just stick with a good stereo setup?" That gave me enough to know that with the right movie, surround sound is fantastic and well worth investigating further.

So now, I really want to learn more about speakers and what makes good sound. I thought that the drivers in these panasonic speakers might make for a worthy low-cost "first build" project/experiment for a novice such as myself. To my inexperienced ear, these speakers have reasonable sound up high, but relatively poor midrange and bass.

So, my thought was: can I take the drivers from these little plastic speakers and build some cabinets that make them sound better? I have disassembled one of the speakers and come up with the following information:

- The speaker is a 2 way design with a volume I would estimate at somewhere between 1 and 1.5 litres. It has a small cylindrical port on the front as well
- The tweeter is about 5 cm in diameter and has 8 ohms printed on the back of it. It also has the "65PH513A2" printed on it (I think, the printing is difficult to read). A quick google for this didn't give me any hits
- The woofer is about 7 cm in diameter and also has 8 ohms printed on the back, as well as "G8P529B2". Unfortunately this didn't get me any hits in google either.
- The crossover seems to consist of a Richey 4.7uF50V capacitor wired to the tweeter.

I was wondering if anyone has any ideas on identifying these drivers? Does anybody think it would be a worthwhile project to build some cabinets for these? Would a nice MDF box of the appropriate volume enhance the frequency response, or are the woofers just too small to be worthwhile experimenting with?

Thanks to anybody who made it this far! Any suggestions or advice would be much appreciated

Cheers,
Michael.

You might learn a little bit about how to built stuff but I doubt you'd improve the sound very much. Likely they are already in an enclosure of the correct volume and the port size is also likely correct.

If you want new cabinets than copy the existing design. Before you could begin to improve the cabinet you wouod need to do a number of sophisticated measurements on the drivers. You would need to determin the

See http://en.wikipedia.org/wiki/Thiele/Small and then
scroll down to the section titled "Measurement techniques"

It is hardly worth theeffort as these drivers will never do what you want. So, first define what you want. Music or movies sound tracks? What size room? What kind of misic. What volume level? Will you be upgrading the amp later? What space do you have, what is the largest size speakers you can use. bigger is always better

[PeteMcK]

FWIW, over the years I collected heaps of drivers from the side of the road, cheap consumer audio speakers that no one wanted,

Last year i tested them and ditched most, but I built a pair of 3 way computer speakers which sound pretty good - used a pair of 20L cabinets, 4" mid-woofer to 1KHz, 4" upper mid to 6 KHz, and cone tweeter above that. That was the best combination based the FR responses.
the hard part is to find a woofer that will respond low enough, many of these drivers have an Fs approaching 100Hz, and at the upper end the response of most cheap drivers is more than a little ragged.

[astute]

Thanks everyone for your replies.

I have a few follow up questions for you, Pete:

1) That ARTA software looks great. Do I need to have a particular kind of microphone to get a useful result, or will a standard computer microphone do the job?
2) The little circuit to use for testing the drivers looks quite simple. When testing the drivers, do you just have them sitting out on a bench or something, or should they be in some type of enclosure? I imagine that they would at least need to be clamped to something so that they don't rattle around?
3) Would using two of the little woofers in a cabinet (perhaps in an MTM configuration) extend the usable low end frequency response? I do have 4 woofers and 4 tweeters to play with after all...
4) I guess the crossover circuit for a MTM configuration would likely be significantly more complex than a normal 2-way configuration?

Thanks again!
Michael.

[PeteMcK]

1: ideally you should use a calibrated mic with a flat frequency response - being tightar$ed I just use an electret lapel mic - using the same mic for all measurements, at least i get consistent results. (most electret/conderser mics are pretty flat, the cheap ones have a peak in the upper mid-lower treble range)

2: for freq response tests, you need to put the drivers on a baffle. For the impedance curve and TS parameters, I hang them from the ceiling on a piece of string...

3: No, 2x a piece of cr@p is just a bigger piece. You may be able to get lower response by trying an 'EBS' alignment, where you tune the box below the Fs of the driver (at the expense of some level)

4: I think most MTMs use at least a 2nd order xover, don't really know much about them

Caveat: this is only my rough & ready approach, others think that more precision is required (which then goes out the window once you start tweaking )

[astute]

Ok, thanks again Pete.

I will use these drivers to have a play with some of the software that you have suggested but I won't bother making new cabinets for them.

Cheers!

[Moondog55]

You can make some improvements with the use of felt and fiberfill, cleans up the midrange a good bit, but don't expect miracles.

[astute]

Hi Moondog,

Can you tell me a bit more about how felt or "fibre fill" might be used, or point me to a link?

Thanks!