I was dismayed to discover one of the tweeters silent on these speakers i have loved for 20 years!
Checked output at the crossover ok, found the tweeter to read about 1K, so unfortunately not broken at the leadouts where a repair can be done. The other reads about 8R. I play loud, but not to have overloaded, but maybe so? I can see the ferrofluid still looking wet in the gap.
Has anyone been through this and where to get a pair of tweets to suit, any ideas most welcome!
Checked output at the crossover ok, found the tweeter to read about 1K, so unfortunately not broken at the leadouts where a repair can be done. The other reads about 8R. I play loud, but not to have overloaded, but maybe so? I can see the ferrofluid still looking wet in the gap.
Has anyone been through this and where to get a pair of tweets to suit, any ideas most welcome!
Ooh, a mylar cone tweeter! Good sound. 
Monacor SPP-90: SPP-90
Monacor HT-22: HT-22/8
Visaton FRS 5X (Which will need an enclosure): FRS 5 X - 8 Ohm
Visaton TW70: TW 70 - 8 Ohm
Some attenuation required too. A couple of resistors. You'll need to work out the crossover circuit. HW 2/70 NG - 8 Ohm
Monacor SPP-90: SPP-90
Monacor HT-22: HT-22/8
Visaton FRS 5X (Which will need an enclosure): FRS 5 X - 8 Ohm
Visaton TW70: TW 70 - 8 Ohm
Some attenuation required too. A couple of resistors. You'll need to work out the crossover circuit. HW 2/70 NG - 8 Ohm
You only need your ears to set tweeter level.
Thing is, you have the speakers in front of you. So since no-one on the entire internet seem to have rolled their sleeves up and delved, it looks like you have to do it here.
Looks like a simple second order 3kHz crossover to me, but I'd need to know the component values.
I have already given you a choice of 4 similar tweeters. Which one fits easiest?
Putting a 22R 10W wirewound across the tweeter and a maybe 6 ohm in series at the front of the filter won't be hard. Wirewound Resistors - Resistors | Maplin
Thing is, you have the speakers in front of you. So since no-one on the entire internet seem to have rolled their sleeves up and delved, it looks like you have to do it here.
Looks like a simple second order 3kHz crossover to me, but I'd need to know the component values.
I have already given you a choice of 4 similar tweeters. Which one fits easiest?
Putting a 22R 10W wirewound across the tweeter and a maybe 6 ohm in series at the front of the filter won't be hard. Wirewound Resistors - Resistors | Maplin
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Of course, why pay inflated ebay prices for a twenty year old tweeter!
That circuit board looks like it has plenty of room for soldering in a couple of 99p resistors to adjust level...
Believe me, you will get these speakers sounding good again. Ideally you'll replace both tweeters for a match. IMO, cone tweeters have a uniquely good sound whatever they are made of. Put me down as a fan.
Measure the cutout size of the tweeter to make some progress, and do what you can with component values, especially capacitors. If you get serious, I'll sim the circuit to give you an accurate first guess on resistor values.
That circuit board looks like it has plenty of room for soldering in a couple of 99p resistors to adjust level...
Believe me, you will get these speakers sounding good again. Ideally you'll replace both tweeters for a match. IMO, cone tweeters have a uniquely good sound whatever they are made of. Put me down as a fan.
Measure the cutout size of the tweeter to make some progress, and do what you can with component values, especially capacitors. If you get serious, I'll sim the circuit to give you an accurate first guess on resistor values.
Cheers for that offer, I'm not an expert at design and modding, just fault -finding and repair. i did try changing the tweeter series cap to a film type, but put the NP back in as it made them too bright and i didn't have faith in my abilities to get them balanced. I still have the caps, so i shall now use them.
The cutout is 66mm diameter, the tweeter cap is 4uF, the other is 8uF, the two inductors are both ferrite cored, but no values printed on them.
I was also wondering would Falcon, Wilmslow or Wembley Speakers have worked out a match for this, as it was used in a lot of Castle Models.
The cutout is 66mm diameter, the tweeter cap is 4uF, the other is 8uF, the two inductors are both ferrite cored, but no values printed on them.
I was also wondering would Falcon, Wilmslow or Wembley Speakers have worked out a match for this, as it was used in a lot of Castle Models.
The Monacor HT22-8 will fit well. It's a good tweeter.
Quick sim suggests 6.2R series in front of the filter and 22R shunt across the tweeter for 6dB reduction. Or an attenuator after the filter of 3.9R and 6.2R.
I'd guess 4uF and 0.3mH tweeter here. Possibly 1.8mH and 8uF on the bass if it's an 8 ohm driver.
You probably needed to add an ohm or so when brightening up to a MKP capacitor over the NP. Every ohm is a 1dB reduction.
Quick sim suggests 6.2R series in front of the filter and 22R shunt across the tweeter for 6dB reduction. Or an attenuator after the filter of 3.9R and 6.2R.
I'd guess 4uF and 0.3mH tweeter here. Possibly 1.8mH and 8uF on the bass if it's an 8 ohm driver.
You probably needed to add an ohm or so when brightening up to a MKP capacitor over the NP. Every ohm is a 1dB reduction.
Have you tried contacting the manufacturer for a replacement? Castle Acoustics is still a going concern. Castle Hifi - Home
I dug up another photo of some Castle Trent biwireable crossover. Looks a doddle to fit in a couple of resistors with all those spare tracks!
Since size is important, I think you might get away with 7W wirewounds which are not too long.
Looks like a couple of polyfuses there, designed to cut out overcurrent condition, but which you could take or leave IMO.
Since size is important, I think you might get away with 7W wirewounds which are not too long.
Looks like a couple of polyfuses there, designed to cut out overcurrent condition, but which you could take or leave IMO.
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Thanks Steve, i shall see about getting your recommended Monacors, also get hid of the protection if it may be detrimental, as they don't need to be idiot proofed. I may ask you for more instruction when i get round to fitting.
I'm going to use a sig gen on my smartphone to compare with the original to get the level right.
Again, i really appreciate the help !
I'm going to use a sig gen on my smartphone to compare with the original to get the level right.
Again, i really appreciate the help !
TBH, bikelectro, I am being conservative with an unknown tweeter crossover because I don't want to blow up your amplifier!
I really don't know what that tweeter coil is. I think I'd try the 3.9 and 6.2 resistor attenuator first. If that gets a bit bright at the very top, we might try a Snell type attenuator which is another way of lowering treble response, and can be flatter. Below.
But if the coil is below about 0.3mH, it can lower impedance dangerously to near 3 ohms. So give my initial idea a go. You might then try 6.2R in series with the monacor HT-22 if the coil is around 0.5mH.
But trust me, we'll fix this. And I hope you have noticed just how cheap that Monacor is. Amazing tweeter IMO.
I really don't know what that tweeter coil is. I think I'd try the 3.9 and 6.2 resistor attenuator first. If that gets a bit bright at the very top, we might try a Snell type attenuator which is another way of lowering treble response, and can be flatter. Below.
But if the coil is below about 0.3mH, it can lower impedance dangerously to near 3 ohms. So give my initial idea a go. You might then try 6.2R in series with the monacor HT-22 if the coil is around 0.5mH.
But trust me, we'll fix this. And I hope you have noticed just how cheap that Monacor is. Amazing tweeter IMO.
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I got the Monocors and fitted one. Using a sig gen app on my phone, I thought things were about right, but on music the new one is much louder. I was wondering whether to buy an L-pad control ( parts express ) in order to get the sound right and then fit appropriate fixed resistors? Where exactly do I fit the resistors?
I told you you'd need to do some attenuation on the tweeter!
About 6dB. 6.2R in front of the filter and 22R across the tweeter. I think we can get away with 7W wirewounds.
Or 3.9R and 6.2R attenuator.
Get a 40W soldering iron from Maplin. Maybe some 30A fuse wire to hook up stuff. And do a bit of surgery.
You could lose those polyfuses too. The left hand nut is the positive input. The right hand is earth. The top is the tweeter filter.
About 6dB. 6.2R in front of the filter and 22R across the tweeter. I think we can get away with 7W wirewounds.
Or 3.9R and 6.2R attenuator.
Get a 40W soldering iron from Maplin. Maybe some 30A fuse wire to hook up stuff. And do a bit of surgery.
You could lose those polyfuses too. The left hand nut is the positive input. The right hand is earth. The top is the tweeter filter.
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