Mate, you've actually got a bit of a bargain (£33!) with those well-behaved and solid chassis Vifa M21 replacement woofers. WJ or WG, well, IDK. The previous owner chose quite wisely. The tweeters are non-ferrofluid, so ought to last. 😀
The crossover is up to you to delve into, but almost a slot-in replacement IMO. My friend fatmarley did great stuff with those high Qms and Qts 0.7 woofers.
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Wilmslow audio have confused the WJ with the WG (which they sell). They are in fact very different drivers.
WJ Qts .24 v c diam 32mm
WG Qts .7 v c diam 25mm
This is all rather confusing, isn't it! 😀
Let's look at the original issue. The original Mission 770S woofers were SEAS P21 REX polycones AFAIK.
http://www.seas.no/images/stories/vintage/pdfdataheet/h0282_p21rex.pdf
Wilmslow Audio are on the money when they say the Vifa P21WO-20-08 polycone is a decent replacement.
Vifa P21WO-20-08 Diameter 215mm
But the seller has fitted a paper cone Vifa M21WJ-09-08, which must be similar to the Le 1.7mH M21WJ-49-08 below and last. It's not quite so compatible IMO, but results depend on the crossover. Which is currently unknown.
So really, Guitarist 28, you need to do a bit of work here. Otherwise you're a blind man poking about without a stick. 🙂
Let's look at the original issue. The original Mission 770S woofers were SEAS P21 REX polycones AFAIK.
http://www.seas.no/images/stories/vintage/pdfdataheet/h0282_p21rex.pdf
Wilmslow Audio are on the money when they say the Vifa P21WO-20-08 polycone is a decent replacement.
Vifa P21WO-20-08 Diameter 215mm
But the seller has fitted a paper cone Vifa M21WJ-09-08, which must be similar to the Le 1.7mH M21WJ-49-08 below and last. It's not quite so compatible IMO, but results depend on the crossover. Which is currently unknown.
So really, Guitarist 28, you need to do a bit of work here. Otherwise you're a blind man poking about without a stick. 🙂
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The original drivers of the Mission 770S are IMO:
Saire ribbed 8" polycone woofer
Seas 1" dome tweeter (H253)
The replacement drivers in Guitarist's speakers are:
Vifa M21WJ-09-08 woofer: http://www.sea.vg/vifa/M21WJ-09-08.pdf
Seas 25TN (H377) tweeter: http://www.seas.no/images/stories/vintage/pdfdataheet/h0337_25tn.pdf
Confusion is only caused by people talking about different driver models. The OP gave the correct information in post #1.
Attachment: Picture of a original Mission 770S
Saire ribbed 8" polycone woofer
Seas 1" dome tweeter (H253)
The replacement drivers in Guitarist's speakers are:
Vifa M21WJ-09-08 woofer: http://www.sea.vg/vifa/M21WJ-09-08.pdf
Seas 25TN (H377) tweeter: http://www.seas.no/images/stories/vintage/pdfdataheet/h0337_25tn.pdf
Confusion is only caused by people talking about different driver models. The OP gave the correct information in post #1.
Attachment: Picture of a original Mission 770S
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Patronising remarks aside, Dissi. 8" bass plus 1" tweeter is just one of those combinations that work as well as a two way can. Good bass and, with a bit of skill, low distortion. Some dispersion issues and compromises remain.
You and I have worked extensively with this one.
The replacement Vifa M21WJ-09-08 paper woofer, below, which you have creditably tracked down, looks easy and well-behaved enough. I have done this sort of thing myself, also below. We all worry that our friends will laugh at our loudspeakers, but TBH, what's hard here? 3 kHz crossover possibly. I'd be quite pleased to have picked these up off flea-bay for £33.
It's up to the OP, Guitarist 28 to flesh out the details. But like a good motor mechanic, you do need to delve under the hood at first. We are not psychic.
You and I have worked extensively with this one.
The replacement Vifa M21WJ-09-08 paper woofer, below, which you have creditably tracked down, looks easy and well-behaved enough. I have done this sort of thing myself, also below. We all worry that our friends will laugh at our loudspeakers, but TBH, what's hard here? 3 kHz crossover possibly. I'd be quite pleased to have picked these up off flea-bay for £33.
It's up to the OP, Guitarist 28 to flesh out the details. But like a good motor mechanic, you do need to delve under the hood at first. We are not psychic.
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Hi All,
Many thanks for your replies. Of all things at the moment, the screws fixing the speakers are in a rather sorry state so I've hopefully ordered some replacements that will fit (allen screws in this instance) and I will be able to remount the speakers in a more robust manner. I have now received my Dayton Audio iMM 6 although I've yet to decide wether to use this with my Samsung phone (cheaper software) or Ipad (Audio Tools - £14.99!).
Regards
Rob
Many thanks for your replies. Of all things at the moment, the screws fixing the speakers are in a rather sorry state so I've hopefully ordered some replacements that will fit (allen screws in this instance) and I will be able to remount the speakers in a more robust manner. I have now received my Dayton Audio iMM 6 although I've yet to decide wether to use this with my Samsung phone (cheaper software) or Ipad (Audio Tools - £14.99!).
Regards
Rob
TBH, Guitarist 28, I do sometimes wonder at the advice dished out here at diyaudio.com. Microphones are all very well, but I trust my ears more. 🙂
Fundamentally, 8 inch bass is an easy speaker. You just have to set tweeter level with the red component. It varies, of course.
Fundamentally, 8 inch bass is an easy speaker. You just have to set tweeter level with the red component. It varies, of course.
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Hi All,
This has been the first opportunity to report back due to work. I've managed to find screws, 3.5M does the trick, bolted the tweeters and drivers properly into place them and just tried them. The line up i'm using is my old Technics 580a CD player, a recently acquired A&R A60 Cambridge (Mag PU input version) and the 770s, QED 75 strand cable. I wish I now had kept my Meridian 101/103 combination but sold these when I bought home cinema.
I have a feeling that there might be a sensitivity mismatch with the amp/cd which was the same when I originally used CD with the 101. I used a QED tuner switching box which helped greatly, but alas this went when I sold amp some years ago
First impressions, bright and edgy to say the least and bottom end i'snt as good as I recall with the old white faced 770s. I was listening to the opening track from Jeff Beals Liberation album and his trumpet was geting very harsh to listen to. I may be expecting far too much from from this set up. I really can't say its easy listening straight off. However, the speakers are very detailed and revealing so I suppose this is a plus.
Any thoughts - given that, less the CD player, its cost me less that £100 so far its pretty much a bargain.
Regards
Rob
This has been the first opportunity to report back due to work. I've managed to find screws, 3.5M does the trick, bolted the tweeters and drivers properly into place them and just tried them. The line up i'm using is my old Technics 580a CD player, a recently acquired A&R A60 Cambridge (Mag PU input version) and the 770s, QED 75 strand cable. I wish I now had kept my Meridian 101/103 combination but sold these when I bought home cinema.
I have a feeling that there might be a sensitivity mismatch with the amp/cd which was the same when I originally used CD with the 101. I used a QED tuner switching box which helped greatly, but alas this went when I sold amp some years ago
First impressions, bright and edgy to say the least and bottom end i'snt as good as I recall with the old white faced 770s. I was listening to the opening track from Jeff Beals Liberation album and his trumpet was geting very harsh to listen to. I may be expecting far too much from from this set up. I really can't say its easy listening straight off. However, the speakers are very detailed and revealing so I suppose this is a plus.
Any thoughts - given that, less the CD player, its cost me less that £100 so far its pretty much a bargain.
Regards
Rob
I've jsut been listening to Queens Greatest Hits 2. Wow it is very 'brash', difficult to listen too and almost painful being so bright. I must say that for a 35 year old amp it can certainly put out some volume.
Regards
Rob
Regards
Rob
IIRC, the AUX jacks of an amp are usually fine for CD output, if it predates CD.
Can you review what you have done here? I'm not sure what the crossover is.
Vifa M21WJ-09-08 woofer: http://www.sea.vg/vifa/M21WJ-09-08.pdf
Seas 25TN (H377) tweeter: http://www.seas.no/images/stories/vintage/pdfdataheet/h0337_25tn.pdf
The tweeter is non-ferrofluid, so should be OK after all the years. The paper woofer might need more crossover work since it replaces a smoother polycone, IIRC. Plus some level adjustment.
But I'm sure we can tune this one up. This is what we do. 🙂
Can you review what you have done here? I'm not sure what the crossover is.
Vifa M21WJ-09-08 woofer: http://www.sea.vg/vifa/M21WJ-09-08.pdf
Seas 25TN (H377) tweeter: http://www.seas.no/images/stories/vintage/pdfdataheet/h0337_25tn.pdf
The tweeter is non-ferrofluid, so should be OK after all the years. The paper woofer might need more crossover work since it replaces a smoother polycone, IIRC. Plus some level adjustment.
But I'm sure we can tune this one up. This is what we do. 🙂
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Hi System 7,
Yes I have used the aux input when listing to the Queen album. I think it must be the original crossover, but I shall take this out and endeavour to supply a schematic.
I've just used a din to phono for connection from the amp to cd.
Regards
Rob
Yes I have used the aux input when listing to the Queen album. I think it must be the original crossover, but I shall take this out and endeavour to supply a schematic.
I've just used a din to phono for connection from the amp to cd.
Regards
Rob
I apologies for the schematic attached as I really struggle to draw these in a logical format. I unsoldered connections to endeavour to get a true value of the components rather than in circuit. Given that these have been glued to the plastic chassis in some cases I've had to go by the value from my multimeter than could be found on the component e.g. the 10uF polyprop capacitor.
However, I hope this helps?
Regards
Rob
https://www.flickr.com/photos/65588479@N08/25875174273/in/dateposted-public/
However, I hope this helps?
Regards
Rob
https://www.flickr.com/photos/65588479@N08/25875174273/in/dateposted-public/
Well done. The previous owner obviously replaced the drivers but wasn't able to adjust the crossover properly. The tweeter apparently is too loud and the impedance is unnecessarily low.
Of course you can try to modify the existing crossover now, but without knowing the actual coil values that's quite speculative. A new crossover probably would be more straightforward.
Of course you can try to modify the existing crossover now, but without knowing the actual coil values that's quite speculative. A new crossover probably would be more straightforward.
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I did forget that I had tester for inductors - assuming it is correct then the coil nearest the SEAS tweeter reads as 1.1R and 0.36mH, the other coil reads as 0.6R and 2.3mH. I do have another means of testing this as I've a signal generator and several oscilloscopes but I cant get to these at the moment as I'm in the middle of decorating!!
Thanks
Rob
Thanks
Rob
Geesus Rob!
Get XSim to draw your schematics it's free, and will save your schematics in a picture format you can upload directly here. 🙂
Best,
Erik
Get XSim to draw your schematics it's free, and will save your schematics in a picture format you can upload directly here. 🙂
Best,
Erik
Dissi is a pretty safe pair of hands with crossovers. 🙂
If this is what we have here, I'd look at that 2.3mH bass coil and say this is a bassy speaker best placed away from the wall.
Working with what we have, if you don't find the bass intrusive, I see problems with the 10uF tweeter capacitor and 0.36mH coil. Capacitor is way too big IMO, and likely to produce a 3kHz midrange peak. 4.7uF might be nearer.
Like I say, I wouldn't use such a big bass coil, but you can fix that later. For now, this tweeter filter might work better at the mid and top end. All you really have to do is adjust the 4.7R resistor for tweeter level. Also amp-friendly impedance.
If this is what we have here, I'd look at that 2.3mH bass coil and say this is a bassy speaker best placed away from the wall.
Working with what we have, if you don't find the bass intrusive, I see problems with the 10uF tweeter capacitor and 0.36mH coil. Capacitor is way too big IMO, and likely to produce a 3kHz midrange peak. 4.7uF might be nearer.
Like I say, I wouldn't use such a big bass coil, but you can fix that later. For now, this tweeter filter might work better at the mid and top end. All you really have to do is adjust the 4.7R resistor for tweeter level. Also amp-friendly impedance.
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Hi Steve,
Thanks for this and I dont find these speakers to bassy and from what I recall of original 770s they are a tad more tighter controlled imho. What wattage resistors do you recommend and are polyprop capacitors ok (e.g. wima's)??
Regards
Rob
Thanks for this and I dont find these speakers to bassy and from what I recall of original 770s they are a tad more tighter controlled imho. What wattage resistors do you recommend and are polyprop capacitors ok (e.g. wima's)??
Regards
Rob