I like the eventual design to play at least as loud over at least the freq range as the originals. So, perhaps we are looking at a 5" mid.
Doug
The Gale used a 4" midrange and so using a similar or "better" 4" midrange is going to work. I suggested the SB 4" mid but if you want efficiency then perhaps the Audax HM100Z0. A 4" midwoofer/fullrange tends to be less efficient and fullrange drivers can have low power handling (I don't know for your driver?). This follows from needing to be able to handle lower frequencies in the way a midrange does not.
The 5" midrange helps both efficiency and a lower crossover for the more wooferish 8" drivers. The cost is a lower crossover frequency for the tweeter and the consequent need to use a reasonable and a bit more expensive 1" tweeter rather than something like the SEAS 19TFF.
It is trivial to connect drivers in series. 
I see a lot of advantages to doing so. Take any decent design and double up the drivers and cabinet volume. All you have to do is then double inductance and resistance, and halve capacitance in the filter for the doubled drivers. By some miracle of the maths it actually sounds right. And has a nicer, higher impedance.
So nothing hard about this one: ScanSpeak-3W-Discovery
I see a lot of advantages to doing so. Take any decent design and double up the drivers and cabinet volume. All you have to do is then double inductance and resistance, and halve capacitance in the filter for the doubled drivers. By some miracle of the maths it actually sounds right. And has a nicer, higher impedance.
So nothing hard about this one: ScanSpeak-3W-Discovery
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It is trivial to connect drivers in series.
I see a lot of advantages to doing so. Take any decent design and double up the drivers and cabinet volume. All you have to do is then double inductance and resistance, and halve capacitance in the filter for the doubled drivers. By some miracle of the maths it actually sounds right. And has a nicer, higher impedance.
So nothing hard about this one: ScanSpeak-3W-Discovery
Hi System7
Thanks. I suspected there would be little problem with a series connection.
To clarify: Are you suggesting I use use the same 3 drivers (& an extra woofer)? ... because Troel's design is ported, not sealed. (I wish to use a sealed design.)
??
Doug
Doug, you're dealing with people who understand how speakers work here.
You're having a laugh mate. That is a reflex driver @Qts 0.33, whatever it is. And why should it be anonymous?
I'm starting to think you are a timewaster.
I was having a joke (on this occasion), as I think I recall (compatriot) PeterMcK posting about Jaycar woofers in previous threads unrelated to this one. Just wanted to see if he'd twig to the identity. Anyway, enough frivolity. Back to the woofer hunt.
Just to reassure you: Building the cabinets will be a doddle for me, as I have access to all the tools I need. All that needs to be settled is whether there exists a modern WMTW combo that will do the job at a reasonable budget.
Thanks Pete. (A Dia-1chi SP8-100, eh?) Plugging in the values to a sealed box calculator gives a very high volume for this one. Perhaps I'm making an error?
Why would you want to connect in series? The obvious configuration is a pair of 8 ohm speakers in parallel to get a 4 ohm design. Unlike in the 70s 4 ohms is not a problem for most amplifiers these days. If you look at an amplifier's power rating for 8 ohm and 4 ohm loads you typically get nearly twice as much power into 4 ohms.
A case for a pair of 4 ohms drivers in series to give an easy 8 ohm load might be a wish to use valve amplifiers. But they would have to be huge ones given you want to use a small sealed box with reasonable bass extension and the laws of physics consequently dictate a lowish efficiency.
I cannot see a reason to use a pair of 4 ohm speakers in parallel to give 2 ohms. Nonetheless there are modestly priced amplifiers around these days that will drive 2 ohms woofers if you wanted to do it. Perhaps if you already owned 4 ohm drivers.
I'd too use 8 Ohm woofers in parallel and 4 Ohm ones in series.
Budget-wise I can't find anything substantially better (going by published figures) than those Beymas I mentioned earlier. They do about 89dB 1W/1m each so two in parallel should be good for 92 or 95dB (I keep forgetting if it is 3 or 6 dB gained) which seems a good match with the 4" Audax you mentioned.
Just not sure if either is easily available in Australia.
Budget-wise I can't find anything substantially better (going by published figures) than those Beymas I mentioned earlier. They do about 89dB 1W/1m each so two in parallel should be good for 92 or 95dB (I keep forgetting if it is 3 or 6 dB gained) which seems a good match with the 4" Audax you mentioned.
Just not sure if either is easily available in Australia.
Zut alors, this thread is hard work. I fixed the broken link so we're singing from the same songsheet for the SP8-100 polycone:
SP8-100 | Wagner Electronics, wagneronline.com.au
The Gale, of course, was highly inefficient acoustic suspension. That uses a very heavy AR cone with a low Qts, and some natural low rolloff.
This SP8 50 paper cone is not really the same animal at all, but is foam surround:
SP8 50 | Wagner Electronics, wagneronline.com.au
It's more like the famous old Vifa M21 with a Qts around 0.7.
I think 2X 4 ohm woofers in series is quite a neat idea if you are horrified by the prospect of a series wired 16 ohm bass section. The problem with all three ways is the low impedance, and having a 4 ohm woofer section only makes it worse.
But it still looks like just a slightly modified standard three way to me.
SP8-100 | Wagner Electronics, wagneronline.com.au
The Gale, of course, was highly inefficient acoustic suspension. That uses a very heavy AR cone with a low Qts, and some natural low rolloff.
This SP8 50 paper cone is not really the same animal at all, but is foam surround:
SP8 50 | Wagner Electronics, wagneronline.com.au
It's more like the famous old Vifa M21 with a Qts around 0.7.
I think 2X 4 ohm woofers in series is quite a neat idea if you are horrified by the prospect of a series wired 16 ohm bass section. The problem with all three ways is the low impedance, and having a 4 ohm woofer section only makes it worse.
But it still looks like just a slightly modified standard three way to me.
I just dug up the specs on those Acoustic Research 8" woofers:
Measurements for 8" woofers and 1.25" tweeter - Acoustic Research - The Classic Speaker Pages Discussion Forums
There's also some Gale measurements:
GS401 Speaker | galeaudio.com
I'm quite surprised that the Gale woofer has a Qts of 0.659 and Fs of 37Hz and Vas of 34L. I thought acoustic suspension used a lower Qts around 0.3.
But in a shared cabinet of about 50L, which was bigger than AR used, it has a Fc of 55Hz looking at impedance, which is quite deep.
Maybe this whole business of finding a suitable closed box woofer is quite easy?
Measurements for 8" woofers and 1.25" tweeter - Acoustic Research - The Classic Speaker Pages Discussion Forums
There's also some Gale measurements:
GS401 Speaker | galeaudio.com
I'm quite surprised that the Gale woofer has a Qts of 0.659 and Fs of 37Hz and Vas of 34L. I thought acoustic suspension used a lower Qts around 0.3.
But in a shared cabinet of about 50L, which was bigger than AR used, it has a Fc of 55Hz looking at impedance, which is quite deep.
Maybe this whole business of finding a suitable closed box woofer is quite easy?
An option aimed at preserving the sound and spirit of the Gale GS401 using standard range drivers might be (price excludes VAT):
- 2 x Dayton RS225-8 (£47.92 each)
- 1 x SB Acoustics SB12MNRX25-4 (£31.95 each)
- 1 x SEAS 19TFF1 (£15.95 each)
- Q=0.7, f3=58Hz in a sealed stuffed 40 litre box
- 4 ohm
- sensitivities around 88 dB
- crossover at approx 500Hz and 5kHz
- 2 x Dayton RS225-8 (£47.92 each)
- 1 x SB Acoustics SB12MNRX25-4 (£31.95 each)
- 1 x SEAS 19TFF1 (£15.95 each)
- Q=0.7, f3=58Hz in a sealed stuffed 40 litre box
- 4 ohm
- sensitivities around 88 dB
- crossover at approx 500Hz and 5kHz
- Status
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