All caps finally extricated from xover board without any serious damage to pcb, tracks or caps, real pain to get off as were glued to pcb & to each other when in pairs, as well as having leads bent over on solder side.
Capacitance values:
High filter:
C6: specified 0.68uF, measured 0.675uF
C7:specified 1.0uF, measured 0.962uF
Mid Filter:
C4: specified 2.2uF, measured 2.37uF
C5: specified 1.5uF, measured 1.45uF
Low Filter:
C1: specified 4.7uF, measured 5.32uF
C2: specified 3.3uF, measured 3.63uF
Capacitors were all marked xuF/100 on one side & ITT GB PMT/2R on reverse, which from web search eg
'High quality Molded Metallized Polypropylene Film Capacitors made by ITT. Excellent capacitor for High Quality Audio Circuits.
How does that sound, I dont have ready access to pspice or other simulation software.
Capacitance values:
High filter:
C6: specified 0.68uF, measured 0.675uF
C7:specified 1.0uF, measured 0.962uF
Mid Filter:
C4: specified 2.2uF, measured 2.37uF
C5: specified 1.5uF, measured 1.45uF
Low Filter:
C1: specified 4.7uF, measured 5.32uF
C2: specified 3.3uF, measured 3.63uF
Capacitors were all marked xuF/100 on one side & ITT GB PMT/2R on reverse, which from web search eg
'High quality Molded Metallized Polypropylene Film Capacitors made by ITT. Excellent capacitor for High Quality Audio Circuits.
- Manufacturer: ITT / GB
- Material: Metallized Polypropylene Film
- Capacity: 2.2uF
- Tolerance: 10% (5% Measured)
- Voltage: 250VDC
- Dimensions: 32x13x23.5mm (LxDxH) excl. Terminals
- Terminal Pitch: 27.5mm
- Terminal length: 30mm
How does that sound, I dont have ready access to pspice or other simulation software.
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Sighs. Looks like the HF 1300 doesn't really output enough level here for decent high ends. 🙁
We must find a substitute. TW 70 - 8 Ohm
Will need some slightly different crossover values, being 8 ohms. Fancy trying it? I'll model it if you are interested.
We must find a substitute. TW 70 - 8 Ohm
Will need some slightly different crossover values, being 8 ohms. Fancy trying it? I'll model it if you are interested.
Had an evening off tonight & just reading through the thread :
Capacitors look OK, unlikely to be problem with coil.
4001s almost inaudible on the high filter but produce a lot more sound when connected to mid filter. As irext pointed out may not be doing 4001 any good with this higher level & lower frequencies?
HF1300s produce decent level on mid filter and reasonable level on high filter, but possibility that lack of hi freqs due to aging, need to check what they sound like on mid filter with L3 shorted out.
Have tried 2 sets of HF1300 but both pairs are old so may be suffering from same fault, likely? Diaphragms aged, can replace, but have read that cones break up?
Revisit listening to 4001 & HF1300 connected to Trio xover to try to see which is failing to produce hi freqs.
2 different replacements recommended, TW70 for HF1300 & H0414 for 4001 (SteveSystem7 to help with diff cap values modelling), or new 4001s (expensive if not fix) still not sure which driver is failing to produce top end, maybe buy cheap tweeter with wide range to experiment with on both filters, before committing?
See if I can setup a frequency response sweep to definitively see where hi freqs missing, currently don't have decent microphone, revisit signals scoped at drive units on scope?
Capacitors look OK, unlikely to be problem with coil.
4001s almost inaudible on the high filter but produce a lot more sound when connected to mid filter. As irext pointed out may not be doing 4001 any good with this higher level & lower frequencies?
HF1300s produce decent level on mid filter and reasonable level on high filter, but possibility that lack of hi freqs due to aging, need to check what they sound like on mid filter with L3 shorted out.
Have tried 2 sets of HF1300 but both pairs are old so may be suffering from same fault, likely? Diaphragms aged, can replace, but have read that cones break up?
Revisit listening to 4001 & HF1300 connected to Trio xover to try to see which is failing to produce hi freqs.
2 different replacements recommended, TW70 for HF1300 & H0414 for 4001 (SteveSystem7 to help with diff cap values modelling), or new 4001s (expensive if not fix) still not sure which driver is failing to produce top end, maybe buy cheap tweeter with wide range to experiment with on both filters, before committing?
See if I can setup a frequency response sweep to definitively see where hi freqs missing, currently don't have decent microphone, revisit signals scoped at drive units on scope?
I really don't think the crossover is the problem. It's the HF1300 which isn't loud enough. It actually does most of the work above 3kHz!
I did think a Monacor HT22-8 was a good substitute after some modelling. This is a £6 cone tweeter much like the HF 1300 in response, if not dispersion. Available at Blue Aran.
I modelled it very roughly tonight. It's gonna look a bit like this. BTW, I found a 0.1mH on the Coles 4001G tweeter was better, but not a biggie. Bottom line, is you attenuate the Monacor and keep it round 16 ohms load. It's a 92mm tweeter with a near 63mm cutout plus leads. Big spade connectors. Resistors should be less than £1 a pop for 10W wirewound aka ceramics. Doubtless some fiddling for level required.
I don't think there is a strong case for changing the Coles 4001G supertweeter or 0.2mH coil, but the diagram shows how you would do it for an 88dB 8 ohm substitute.
My intuitive methods frequently have other people here throwing there hands up in horror, but TBH, I've never had a disatisfied customer. 😀
I did think a Monacor HT22-8 was a good substitute after some modelling. This is a £6 cone tweeter much like the HF 1300 in response, if not dispersion. Available at Blue Aran.
I modelled it very roughly tonight. It's gonna look a bit like this. BTW, I found a 0.1mH on the Coles 4001G tweeter was better, but not a biggie. Bottom line, is you attenuate the Monacor and keep it round 16 ohms load. It's a 92mm tweeter with a near 63mm cutout plus leads. Big spade connectors. Resistors should be less than £1 a pop for 10W wirewound aka ceramics. Doubtless some fiddling for level required.
I don't think there is a strong case for changing the Coles 4001G supertweeter or 0.2mH coil, but the diagram shows how you would do it for an 88dB 8 ohm substitute.
My intuitive methods frequently have other people here throwing there hands up in horror, but TBH, I've never had a disatisfied customer. 😀
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System7Steve, really do appreciate all your kind efforts on my behalf, looks like you keep nearly as weird hours as I do!
I will order some Monacor HT-22/8s as you suggest, as a possible replacement for the HF1300s and if nothing more they at least give me a new known working quantity to try substitution with and at a price that it doesn't matter if they don't prove to be the final solution or indeed if I kill them during experimentation!
I think I will hold off on replacing the 4001 until I have tried the Monacor HT-22/8s. I see you have recommended VISATON G20SCs as well as the SEAS 19TAF-G, both 8 ohm metal dome. Can I try the HT-22/8 on the hi filter as a sub for the 4001 as an expt?
Will replace all the caps in the pcb as they are all in tolerance & it doesn't look from your responses that I need diff values. BTW what would be the expected effect on the HF1300 of shorting out L3, I presume it would be to extend the output freq up to its max, I might try that.
BTW I have seen that you can replace the diaphragms on HF1300s, anyone tried this? Is it simple. What is cone breakup, mentioned in earlier response?
I will order some Monacor HT-22/8s as you suggest, as a possible replacement for the HF1300s and if nothing more they at least give me a new known working quantity to try substitution with and at a price that it doesn't matter if they don't prove to be the final solution or indeed if I kill them during experimentation!
I think I will hold off on replacing the 4001 until I have tried the Monacor HT-22/8s. I see you have recommended VISATON G20SCs as well as the SEAS 19TAF-G, both 8 ohm metal dome. Can I try the HT-22/8 on the hi filter as a sub for the 4001 as an expt?
Will replace all the caps in the pcb as they are all in tolerance & it doesn't look from your responses that I need diff values. BTW what would be the expected effect on the HF1300 of shorting out L3, I presume it would be to extend the output freq up to its max, I might try that.
BTW I have seen that you can replace the diaphragms on HF1300s, anyone tried this? Is it simple. What is cone breakup, mentioned in earlier response?
I finish work at 2AM a lot of nights, and unwind here... it makes me think. 😀
The DM4 is a speaker I heard years ago, along with the bigger but similar DM2. Bexrene bass was always good for classical music, but lacked dynamics for Rock.
Surprisingly, and I just can't explain it beyond noticing it works with the 3.3uF to produce a 8kHz resonant peak, removing 0.1mH L3 actually reduces the top end output of the HF 1300. So not recommended.
I'm just using the soft-dome Visaton G20SC as a modelling guide, since tweeters are tweeters IMO. I just like to get a feel for how the circuit works. But actually, metal domes like the SEAS 19TAF/G are better on detail IMO.
But keep the mylar Coles 4001G supertweeter as it is, I reckon. Nothing wrong with it.
Glad you're willing to have a bash with the Monacor HT22-8. It works well enough on 2.5kHz crossover. I like it a lot. Metal dustcap, you see.
Personally I might also shunt a, say, 33R 3W across the Coles for a better supersonic impedance, which is something I can hear, making the amp more stable and making for a cleaner sound.
Cone breakup is where the cone goes into all sorts of asymettric breakup modes. It sounds fuzzy and harsh. Usually kicks in above 5kHz with 6" drivers. Best to have the driver well rolled off (>10dB down) at this point.
https://www.klippel.de/fileadmin/klippel/Files/Know_How/Literature/Papers/KLIPPEL_Cone_Vibration_Poster.pdf
Can't comment on replacement diaphragms for the HF 1300, but I don't think it's going to help.
The DM4 is a speaker I heard years ago, along with the bigger but similar DM2. Bexrene bass was always good for classical music, but lacked dynamics for Rock.
Surprisingly, and I just can't explain it beyond noticing it works with the 3.3uF to produce a 8kHz resonant peak, removing 0.1mH L3 actually reduces the top end output of the HF 1300. So not recommended.
I'm just using the soft-dome Visaton G20SC as a modelling guide, since tweeters are tweeters IMO. I just like to get a feel for how the circuit works. But actually, metal domes like the SEAS 19TAF/G are better on detail IMO.
But keep the mylar Coles 4001G supertweeter as it is, I reckon. Nothing wrong with it.
Glad you're willing to have a bash with the Monacor HT22-8. It works well enough on 2.5kHz crossover. I like it a lot. Metal dustcap, you see.
Personally I might also shunt a, say, 33R 3W across the Coles for a better supersonic impedance, which is something I can hear, making the amp more stable and making for a cleaner sound.
Cone breakup is where the cone goes into all sorts of asymettric breakup modes. It sounds fuzzy and harsh. Usually kicks in above 5kHz with 6" drivers. Best to have the driver well rolled off (>10dB down) at this point.
https://www.klippel.de/fileadmin/klippel/Files/Know_How/Literature/Papers/KLIPPEL_Cone_Vibration_Poster.pdf
Can't comment on replacement diaphragms for the HF 1300, but I don't think it's going to help.
I'd be inclined to try new HF1300 diaphragms first just out of curiosity if nothing else. I assume they are not hugely expensive. You had previously found them satisfactory when you first bought them so something has changed. If it was your hearing then every speaker you listened to would be lacking in HF. I know my hearing top end has deteriorated over the years but speakers I liked 20 years ago I still like. I've had KEF T27s which had identical DC resistances and appeared to be in perfect order but had quite different acoustic outputs. If the diaphragms do the job then nothing else needs to be altered. If they don't then you've got two pristine HF1300s to put on fleabay and go ahead with System 7s very helpful advice.
I can only find replacement diaphragms for 4 & 8 ohms HF1300s (French Ebay see link below), unless someone knows better?
Replacement Diaphragm Tweeter Celestion HF1300 Ditton 25 8 Ohms | eBay
Replacement Diaphragm Tweeter Celestion HF1300 Ditton 25 8 Ohms | eBay
Ive noticed a discrepancy on the B&W circuit diagram and the circuit & photo of back of xover pcb from earlier post from Malefoda, the 2 capacitors 1u & 0.68u in the hi pass filter are reversed. System7Steve could you model the 2 filters to see if there is any significant difference to the hi freq response, if Malefoda's is better I will change round the caps. BTW what modelling sw do you use, any recommendations?
Traditionally, the 0.68uF comes first, before the coil. The bigger 1uF one is after the coil. Simple as that.
I was scratching my head why the HF1300 is negative polarity. That is not what you usually get with 6" bass and tweeter. By my reckoning it works better positive polarity. The Coles stays negative polarity.
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So it may be. But the 8" bass Spendor BC1 was positive polarity too.
Spendor BC1
Not wildly dissimilar to a DM4. 🙂
I quite wish I had this speaker on my bench. 😀
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There's one big difference - the DM4 has 2nd order filters and the Spendor has 3rd order.
I'd like a pair on stands in my room.
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