Well, your contribution can be as useful as anyone's if you know what to look for! 🙂
I particularly like this combination of 8" plus tweeter drivers, and can always learn stuff myself.
What we can do here is fine tune your crossover to get the replacement woofer sounding good. It would be useful to know the Foster woofer model number too.
Crossovers make more difference to the sound than drivers, often as not. And it's a cheaper fix than new drivers. But some driver combinations are just sweet.
I particularly like this combination of 8" plus tweeter drivers, and can always learn stuff myself.
What we can do here is fine tune your crossover to get the replacement woofer sounding good. It would be useful to know the Foster woofer model number too.
Crossovers make more difference to the sound than drivers, often as not. And it's a cheaper fix than new drivers. But some driver combinations are just sweet.
Peter Snell was a very good speaker designer with very good ears. On new speakers he'd built, he used to fine tune the crossover values until his speakers matched a reference pair to within +/-0.5db.
If you bought a new Vifas M21 driver from him he would also supply the correct inductor for that woofer.
This is memory lane for me, but I once got involved in a thread about the Snell Type E.
IIRC, it was a tweeter filter around 6uF/0.6mH and an adjustable 0-5R resistor after the filter.
The bass coil I can't remember, but 2.5mH and 6uF might make sense. Probably wires negative polarity on the tweeter.
This eBay example seems to confirm most of that, though it looks to me the resistor goes in front of the filter. Which might explain why the guys "upgrade" didn't work! 🙄
IIRC, it was a tweeter filter around 6uF/0.6mH and an adjustable 0-5R resistor after the filter.
The bass coil I can't remember, but 2.5mH and 6uF might make sense. Probably wires negative polarity on the tweeter.
This eBay example seems to confirm most of that, though it looks to me the resistor goes in front of the filter. Which might explain why the guys "upgrade" didn't work! 🙄
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I looked the Snell E up today, and this might be more help to fatmarley than anyone else if he doesn't already know this, but the bass section for the Vifa M21 is 2.5mH and 12uF crossing over at 2kHz according to stereophile. Snell Type E/III loudspeaker Measurements | Stereophile.com
Seriously bassy I would think. Especially in that big reflex box. And quite demanding on the tweeter which varied a lot but always a Vifa model. It's an efficient speaker. Much tougher to do in a small box I'd reckon.
Seriously bassy I would think. Especially in that big reflex box. And quite demanding on the tweeter which varied a lot but always a Vifa model. It's an efficient speaker. Much tougher to do in a small box I'd reckon.
The Snell E used a similar woofer but different specs to the one used in the JPW AP, Snell k and Heybrook HB1.
Someone on another forum measured the Snell K components and got this:
"Speaker A .
LF filter 2.3mH and 12uF
HF filter 8.8uF 1.6 Ohm variable resistor and 0.31mH inductor
Speaker B
LF filter 2.42mH and 11.4uF
HF filter 7.5 uF , 1.7 Ohm 0.58mH"
It's a shame he didn't measure the DCR of the inductors. I was told they are aircore, so must be pretty high DCR.
Someone on another forum measured the Snell K components and got this:
"Speaker A .
LF filter 2.3mH and 12uF
HF filter 8.8uF 1.6 Ohm variable resistor and 0.31mH inductor
Speaker B
LF filter 2.42mH and 11.4uF
HF filter 7.5 uF , 1.7 Ohm 0.58mH"
It's a shame he didn't measure the DCR of the inductors. I was told they are aircore, so must be pretty high DCR.
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Looks like the Fosters have succumbed to foam rot like the original Vifas...😱
I take it those speakers are closed box around 30 litres?
I think you could fit almost any 8" bass, albeit a lot of the modern types would need a reflex port added. I'm not sure I'd throw a lot of money at this, but I don't know what is easily available in Oz. A polycone or a high efficiency paper bass would both seem viable.
You still haven't dug up the crossover details...😉
I take it those speakers are closed box around 30 litres?
I think you could fit almost any 8" bass, albeit a lot of the modern types would need a reflex port added. I'm not sure I'd throw a lot of money at this, but I don't know what is easily available in Oz. A polycone or a high efficiency paper bass would both seem viable.
You still haven't dug up the crossover details...😉
well like i said, i can buy the original Vifas for $240AUD the pair.
Is it worth that kind of cost?
And when im down in my shed tommorow i will ensure to measure it all up for you! 🙂
Is it worth that kind of cost?
And when im down in my shed tommorow i will ensure to measure it all up for you! 🙂
ARE the Fosters rotted?
What's best here depends on an initial assessment. This sort of picture tells most of what you need to know.
There's certainly no need to slavishly replace like with like with such simple designs. I never really understand why people pay huge prices on eBay for old drivers.
What's best here depends on an initial assessment. This sort of picture tells most of what you need to know.
An externally hosted image should be here but it was not working when we last tested it.
There's certainly no need to slavishly replace like with like with such simple designs. I never really understand why people pay huge prices on eBay for old drivers.
I have just recently refoamed a pair of Videotone. Very cheap way back and not worth spending big money. The results have been assessed over the last few days. Sounds quite good.
The drivers in question are new, old design drivers. I wouldnt pay that much for an old driver. Plus here in oz you will pay that price anyway for a crap driver. Also the reason i am wanting to fix these speakers is the fact that a few months ago i got a pair of monitor audio r100 speakers (woofer in your photo looks the same) that are British and i love the sound of them, even though they are at the bottom of the monitor audio line.
And yes the foam has completely vanished, gone to the same place lost socks go.
And yes the foam has completely vanished, gone to the same place lost socks go.
Audio Parts in Germany are quite good prices but they don't know their product.
They sent two surrounds that did not fit the speakers they said were OK.
Just remembered they are owe me money for sending 2/3rds of my order wrongly.
Must chase them up.
Alles om uw luidsprekers te repareren, foamranden, rubber randen, membranen, tweeters enzovoorts
Speaker repair shop are MUCH better.
I can recommend them.
There is an english language section in there somewhere. I can't do German.
Got it
http://speakerrepairshop.com/index.php?action=showbasket&lang=EN
They sent two surrounds that did not fit the speakers they said were OK.
Just remembered they are owe me money for sending 2/3rds of my order wrongly.
Must chase them up.
Alles om uw luidsprekers te repareren, foamranden, rubber randen, membranen, tweeters enzovoorts
Speaker repair shop are MUCH better.
I can recommend them.
There is an english language section in there somewhere. I can't do German.
Got it
http://speakerrepairshop.com/index.php?action=showbasket&lang=EN
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thanks Andrew!
Here in oz i use QSR (Queensland Speaker Repair) more expensive but with postage and our weak dollar it works out cheaper compared to overseas.
Here in oz i use QSR (Queensland Speaker Repair) more expensive but with postage and our weak dollar it works out cheaper compared to overseas.
The Monitor Audio R100 was doubtless a Robin Marshall design. The filter is below if I'm guessing right. You can fit almost any 94mm 88dB tweeter without crossover change. Later models got a H0414-08 19TAF/G
I wouldn't modify the cabinet, but some stuffing like a pillow might help.
I know all about that Vifa bass. But it's not the only game in town. For your JPW, see if you can dig up a cheap bass we can evaluate. Like this:
H1471-08 CA22RNY
See it hardly needs any filtering! 😎
I wouldn't modify the cabinet, but some stuffing like a pillow might help.
I know all about that Vifa bass. But it's not the only game in town. For your JPW, see if you can dig up a cheap bass we can evaluate. Like this:
H1471-08 CA22RNY
See it hardly needs any filtering! 😎
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Pics left and middle show a steeper roll off of the bass/mid relative to the roll off of the treble, even though the bass/mid has a single pole filter and the treble has a 2pole filter.
That's a toughie! You'd need to do some serious research to find a good replacement. Crossover complexity. Woofer material and efficiency and dimensions. Woofer Le inductance and DC resistance. Looks like an AE special to me. But doable I expect. 🙂
The slopes are down to the big natural rolloff that an 8" bass has. There's a much better filter for 8" bass, based on the similar KEF Celeste III and Celestion filters. But it works the bass chassis harder, and I don't really like it with ringing pressed steel chassis.
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I went and took a photo and drew a schematic of the crossover for you today system. As i said earlier though, unfortunately all the component values are hidden. I also went and got a quote on those seas drivers you linked me and they are going to cost more then the vifas! Hifi here in oz is so expensive.
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