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Multi-Way Conventional loudspeakers with crossovers

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Old 16th May 2012, 09:44 AM   #1
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Default Old project - Active 3-way - Update/Rebuild/Replace?

This was my first speaker project, I must have started building them around 6 years ago when I was a poor starving student. I had tried to build the best I could with the budget I had at the time. Clearly I did not do enough research at the time.

The mid and tweeter were crossed at 5K with a cheap pre-made crossover and web calculator L-pad. The main woofer was then crossed at around 2k with an Elliott sound P09 electronic crossover. 300 and 3k would probably have been better starting points.

I have finally started catching up with my backlog of projects and finally got around to anther p09 with a 300hz crossover frequency. Plugged it in yesterday and things sounded decidedly worse.

Today I decided to pull things apart and have a play around. The sealed mid partition is 5.5L and the main cab is 28L with a 65x200mm port and a shelf brace. There is a sealed section behind the tweeter that is not really needed.

The first thing I did was to remove the 5k crossover and run the old active crossover between mid and tweeter - this was the best I have ever heard these speakers sound, this is what I had wanted them to sound like when I first made them!

I had a couple of sets of tweeters to try out seeing that the original was very shrill and coarse sounding. First up was the Vifa BC25TG15-04, again a
vast improvement over what was there before. Next up was the Nuance TW5-120LR, these impressed me - especially considering the price. While the Vifa did sound better than Nuance it did seem to stand out while the Nuance seemed to match the rest of the speaker better. I did need need to cut back the gain on the tweeters considerably as the mid is not very efficient.

I am currently running 2 Elliott sound P3A amps and a JLH class A along with the two electronic cross overs. I am not sure these speakers are on par with the equipment driving them.


Current Options:

1 - Design an build a decent passive crossover for these and build a new set of speakers with the active set-up in mind - 8-10" woofers .

2 - Replace the drivers with better performing units where appropriate and adjust the mid/high active crossover to suit. Tweeters will be changed. Could move to more sensitive woofers? two 6" drivers per cab? Aura NS6-255-8A?

3 - Build a new cabinet with better driver placement/tuning and recycle existing woofers.

Budget would be up to around $500 for replacement drivers. I'm not too fussed on the price of MDF/Ply.

Here are the speakers with the new tweets:
Click the image to open in full size.

Click the image to open in full size.


Original Tweeter:
25mm Titanium Dome Tweeter - Jaycar Electronics
Click the image to open in full size.

I managed to find the specs for the woofers online through an old jaycar catalogue.

4":
Click the image to open in full size.

6.5" woofer:
Click the image to open in full size.
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Old 16th May 2012, 02:42 PM   #2
AllenB is online now AllenB  Australia
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You have a number of options here. When I first looked at these I thought of removing the midrange, adding one extra woofer for a 2-way or 2.5-way, and crossing to a tweeter at a lower frequency, say more like 2kHz.

Based on your descriptions I might assume you'd benefit from greater control in your crossovers. The way you tailor a driver's response has a lot to do with how it sounds and even less expensive drivers can sound good. Passive or active is not the bigger issue.

Your new tweeter seems to have a waveguide. I see this as a step in the right direction as long as it can go reasonably low.
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Old 16th May 2012, 08:03 PM   #3
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Quote:
Originally Posted by AllenB View Post
You have a number of options here. When I first looked at these I thought of removing the midrange, adding one extra woofer for a 2-way or 2.5-way, and crossing to a tweeter at a lower frequency, say more like 2kHz.

Based on your descriptions I might assume you'd benefit from greater control in your crossovers. The way you tailor a driver's response has a lot to do with how it sounds and even less expensive drivers can sound good. Passive or active is not the bigger issue.

Your new tweeter seems to have a waveguide. I see this as a step in the right direction as long as it can go reasonably low.
Cheers Allen,

Removing the mid would require new cabinets as the existing ones are pretty well glued with a solid shelf located just under the mid. I don’t mind making new cabinets though.

The crossovers are set at 300 Hz and around 2 KHz - I’ll have to open up my old cross-over to confirm this. The improvement is massive over the ~2K and 5K crossovers. Low end performance is vastly improved.

The main issue is how inefficient the mid is, I have to attenuate the tweeter by a large degree to compensate. There looks to be a lot of inefficient 4” mid-bass speakers out there. I could always put in a larger mid is the 5L space - 5" or 6"?

I really like the idea of adding an extra woofer, will I need a bigger cabinet or will the 28L be ok? I will need new woofers to do this as the originals are no longer stocked at Jaycar.

The new tweeters do sound considerably better than the originals.

Maybe 6" mid and 2 8"s in a larger cabinet?

Last edited by jacobthellamer; 16th May 2012 at 08:05 PM.
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Old 17th May 2012, 03:30 AM   #4
AllenB is online now AllenB  Australia
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Quote:
Originally Posted by jacobthellamer View Post
The crossovers are set at 300 Hz and around 2 KHz ..... The improvement is massive
I would guess this has more to do with the resulting response, than about which driver was covering what range (in this case).

Quote:
~2K and 5K crossovers.
This is little more than an octave apart and may have caused difficulty in achieving the goals considering that the two would interact, in fact the mid may have had little significant involvement. Broadly speaking, when there is a choice it is better to use a lower crossover.

Quote:
There looks to be a lot of inefficient 4 mid-bass speakers out there.
It's difficult to get a 4" driver to do bass without compromising something. If it's a mid you want, look for one with a higher fs.

Quote:
I could always put in a larger mid is the 5L space - 5" or 6"?.....Maybe 6" mid and 2 8"s in a larger cabinet?
The question is why? I can understand the motivation behind choosing interesting drivers and going from there, which you can still do but there is more to it.

I suppose I could ask a few questions to get you started. Do you listen loud or comfortable? Do you like a particular tone - clean? excessive bass? Can you build any sized speaker? Would you allow subs? What do you see are the benefits of three-ways?
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Old 17th May 2012, 06:44 AM   #5
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Quote:
Originally Posted by AllenB View Post
I would guess this has more to do with the resulting response, than about which driver was covering what range (in this case).

It's difficult to get a 4" driver to do bass without compromising something. If it's a mid you want, look for one with a higher fs.

The question is why? I can understand the motivation behind choosing interesting drivers and going from there, which you can still do but there is more to it.
The current 4" does seem to be holding the whole thing back. I would be happy to leave the drivers and build a suitable passive crossover then move on. I would want them passive as I don't want to mess round with the amps and crossovers just to listen to them. I can create new speakers if it is not worth shoe-horning new drivers into these cabinets.

Quote:
I suppose I could ask a few questions to get you started. Do you listen loud or comfortable? Do you like a particular tone - clean? excessive bass? Can you build any sized speaker? Would you allow subs? What do you see are the benefits of three-ways?
I mostly listen to speakers at comfortable volume - around the level of conversation. I do like to listen loud every now and again.

I suppose I like speakers to sound clear and well defined - like good headphones do. I don't like it when lots of instruments/notes are occur at once and the speakers kind of smear them together. I like clean bass that extends down quite low.

I have a Velodyne CHT-R10 sub available if I need it to cover the very bottom end.

The speakers will be used in a large lounge and will be used for both music and movie duties. My musical tastes include a very large diversity of music so the speakers will have to be handle everything from drum and bass to opera.

I can build a larger speaker but within reason as not to upset Lisa too much

I wanted three ways when I first made the speakers because they seemed like a worth while concept at the time. Now I just want to make use of the amps and electronic crossovers I have built for the project. I already have some nice 2-ways (EV interface 1 series II) as a restoration project and a cheap pair of wide baffled 2-way speakers that I have built just for tinkering with.
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Old 17th May 2012, 07:29 AM   #6
AllenB is online now AllenB  Australia
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Looks like you are flexible I'd be happy to give you a few pointers on getting the best out of your current drivers if you'd like to link the specs (such as the tweeter, and response charts if available)....or, on the other hand discuss something new. I'm partial to wide baffle two-ways myself, or the EVs as they would already be crossed. They are known to need restoration.

Quote:
I don't like it when lots of instruments/notes are occur at once and the speakers kind of smear them together. I like clean bass that extends down quite low.
If you can get a speaker working and balanced, treat the cabinet and room a little and place them well, you should appreciate the difference.

Quote:
I have a Velodyne CHT-R10 sub available if I need it to cover the very bottom end.
Subs (plural) are a good way to balance your bass with regards to room modes, which is based on where you place them. Even if you don't feel the need for the extension or volume.

This pic is from the above link
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Old 18th May 2012, 12:39 AM   #7
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Cheers Allen

I think I will put a passive crossover in the existing speakers so that they are working and finished. Once I have finished with the crossover I will move on to something new entirely

I could not find any response charts for any of the speakers but did find a couple of old threads on the drivers, apparently the 6.5" is not verry good with reproducing mid's. It definitely sounds decent crossed at 300hz and unpleasant crossed at 2k. What do you think about 5-600Hz down low and 4.5K up high?

The EV cabs have definitely seen better days but the drivers still sound good. I have been thinking about making new cabinets out of MDF to the original dimensions. The hardest part will be replacing the acoustic lens. I have already have fixed one tweeter as the connection between the coil and terminal had oxidized right through, I also added a drop of mineral oil in to aid the dried up Ferro fluid. I think I will make a new thread when I finally get to work on them properly

Here are the specs for the tweeter:
Quote:
Nuance TW5-120LR 1/2" Mylar Tweeter


Clean and efficient Mylar diaphragm tweeter. Flush mounts into 5/8" depth recess. Buyout, limited quantities.
Specifications: • Power handling: 20 watts RMS/40 watts max • VCdia: 1/2" • Impedance: 8 ohms •Re: 6.2 ohms • Frequency response: 4,000-20,000 Hz • Fs: 4,000 Hz • SPL: 91 dB 1W/1m • Dimensions: Overall diameter: 4-3/4", Cutout diameter: 1-7/8", Depth: 2".
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Old 18th May 2012, 01:49 PM   #8
sreten is offline sreten  United Kingdom
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Hi,

You might get way with crossing the bass and mid with a first order
series x/o at around the baffle step frequency. This should give you
decent bass to mid balance, you wan't the mid to be less efficient
than the bass unit for this to work well and it is by 3dB, ~ 400Hz.

The nuance tweeter wiil work remarkably well with a single cap (and L-pad) :
see Zaph|Audio and find the Nuance tweeter.
2.7uF gives a classic 3rd order roll-off at 3.3KHz.

The titanium dome is here :
http://www.jaycar.com.au/products_uploaded/CT2007_2.pdf

The top end of the mid I cannot comment on without a response graph.

rgds, sreten.
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Old 19th May 2012, 05:05 AM   #9
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Thanks for the help sreten,

I put together this crossover today(47u instead of 50u, and 5 instead of 5.3 in the Lpad), sounds good. Let me know if there is anything I should change.
Click the image to open in full size.

I recycled the old cheap crossover board and inductor. I just added more turns until the inductor measured .385mH.
Click the image to open in full size.
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Old 19th May 2012, 06:12 AM   #10
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I was my phone as the source when testing earlier for convenience. I just switched to something better - They actually sound very good indeed!

Thanks Allen and sreten!

I'll put up a thread for the replacement speakers soon.
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