I just bought a used set and the original tweeters had been changed out to the Morel MDT29 4 ohm tweeters. This seems to be a common replacement but I was hoping to find something better. The Morels sound "forward" if that is the correct term. I am trying Kef T33 SP1197 at the moment. They us a smaller magnet so a thin spacer behind them is required to mount them. They sound more neutral than the Morels but I'm going to have to listen to them for awhile before I know if I'm going to stick with them. Has anybody found a better match for 104/2's.
The Kef T33 SP1197 is the original 4 ohm tweeter, AFAIK.
Explore KEF - Reference Series Model 104/2 - KEF United Kingdom
The Morel MDT29 4 ohm is a suitable replacement by all accounts:
https://www.youtube.com/watch?v=YlZuaTBnzLQ
The Morel has a removeable front faceplate that makes this doable, but as you say, the spacing needs some bodging.
Nevertheless some sensitivity adjustment is often needed. You could either put an ohm or more in front of the tweeter filter to take the Morel down at the top end, or fit about 1 ohm/10ohm attenuator to generally reduce output if it sounds forward. We are talking a couple of dB here. I've used this tweeter in 8 ohm version so I know what it sounds like. Taking out the 10uF in the tweeter filter out would reduce the very top output a bit too.
Getting tweeter level right is one of the more critical adjustments. Often a single dB will make or break. Soft domes are soft domes IMO. They all sound much the same. I see a reasonable stab at one of KEF's 4 ohm filter below. Not sure how the Martin Colloms quoted R104II schematic relates to your model, but the 3rd order tweeter filter is as expected for 4 ohms.
Explore KEF - Reference Series Model 104/2 - KEF United Kingdom
The Morel MDT29 4 ohm is a suitable replacement by all accounts:
https://www.youtube.com/watch?v=YlZuaTBnzLQ
The Morel has a removeable front faceplate that makes this doable, but as you say, the spacing needs some bodging.
Nevertheless some sensitivity adjustment is often needed. You could either put an ohm or more in front of the tweeter filter to take the Morel down at the top end, or fit about 1 ohm/10ohm attenuator to generally reduce output if it sounds forward. We are talking a couple of dB here. I've used this tweeter in 8 ohm version so I know what it sounds like. Taking out the 10uF in the tweeter filter out would reduce the very top output a bit too.
Getting tweeter level right is one of the more critical adjustments. Often a single dB will make or break. Soft domes are soft domes IMO. They all sound much the same. I see a reasonable stab at one of KEF's 4 ohm filter below. Not sure how the Martin Colloms quoted R104II schematic relates to your model, but the 3rd order tweeter filter is as expected for 4 ohms.
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The sp1191 is the original and the sp1197 has a smaller magnet. I might try to adjust the level of the morel down a couple db.
I don't know how well I can describe this, but you could listen to the Morel 30 degrees off axis, and if it then sounds reasonable, that suggests it's the very top around 10kHz that needs taming. A zobel around 6 ohms and 2uF might do that as an alternative to taking out the 10uf. You could even remove the 10uf and add the zobel for a serious impact on the very top end without mucking up impedance.
Impedance Equalization (L-Pad) Circuit Designer / Calculator
If it's still forward around 3kHz, the whole thing needs attenuating. Presumably the T33 SP1197 is just quieter than the SP1191. But it would be worth measuring its DC resistance.
I certainly hate an overly bright speaker. But there is always the issue of whether the speaker is designed to be toed in to the listener or pointed straight ahead for best result, because top end dispersion inevitably falls off off-axis.
Impedance Equalization (L-Pad) Circuit Designer / Calculator
If it's still forward around 3kHz, the whole thing needs attenuating. Presumably the T33 SP1197 is just quieter than the SP1191. But it would be worth measuring its DC resistance.
I certainly hate an overly bright speaker. But there is always the issue of whether the speaker is designed to be toed in to the listener or pointed straight ahead for best result, because top end dispersion inevitably falls off off-axis.
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I don't know if this tip is important for the acurate tonal balance :the Kef 104/2 were optimized for a front wall at around 60 cm of the speakers (never knew if it was from the rear side or the front side !).
Mine (first mono wired model) sound good and not shiny with the original tweeter. It rocks, but not in all rooms... I find them to be a snapy and dynamic speaker despite its poor 50 Hz at -2 db and its mat treble... mid-bass is very pleasant.... hum off topic but just to say you don't need climbing treble for a snapy mid-bass with this speaker !
Mine (first mono wired model) sound good and not shiny with the original tweeter. It rocks, but not in all rooms... I find them to be a snapy and dynamic speaker despite its poor 50 Hz at -2 db and its mat treble... mid-bass is very pleasant.... hum off topic but just to say you don't need climbing treble for a snapy mid-bass with this speaker !
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I tried using the morel in one speaker and the Kef sp1197 in the other and did some listening tests. I'm going to remove the morel and install the other sp1197. The morel just doesn't match as good as the sp1197 to the midrange units. I have them about 2' from the back wall and about 6' from the side walls. The room is about 16' X 20'. I've tried two different amps with the same results. A Yamaha A-1020 and a Dynaco st-70.
I found a direct replacement at Midwest Speaker Repair. https://www.midwestspeakerrepair.com/mw-audio-mt-1191-1-inch-dome-tweeter-for-kef-104-2-speaker. No modifications needed and it sounds great. I listened to two 24-bit 92 mHz remixes buy Steven Wilson and the clarity, definition and presence is awesome. I never appreciated my KEF's so much. KEF wanted $150 each for a replacement and I has to ship them back the entire speaker section. These were $45 each.
I do not have the equipment to measure curves and even if I did I did not have any working tweeters to compare against. I acknowledge that my assessment is purely subjective. Since I did not have any T33 speakers that were repairable, these replacement speakers were my best option and I am quite pleased.
What are you trying to debug? Everywhere I've read folks are looking for a replacement 4 ohm speaker for the 30-year old T33. Here is an option. Maybe someone can measure the curve, but to me that is irrelevant. The speaker is a direct replacement with no physical mods and sounds great. I'm not a high end audiophile, but I'm am a happy listener again.
normd;
thanks for the lead and your comments.
i'm one of those 30 year + owners in need of replacement tweeter.
i'll definitely order when they get more in stock.
mlloyd1
thanks for the lead and your comments.
i'm one of those 30 year + owners in need of replacement tweeter.
i'll definitely order when they get more in stock.
mlloyd1
hi normd:
a couple of questions if you don't mind:
1. are you still liking those kefs ? (just kidding, of course you are 🙂 )
2. did you order a pair of tweeters or just one? i am curious about matching if purchasing a pair.
thanks,
mlloyd1
a couple of questions if you don't mind:
1. are you still liking those kefs ? (just kidding, of course you are 🙂 )
2. did you order a pair of tweeters or just one? i am curious about matching if purchasing a pair.
thanks,
mlloyd1
Yes, I have the KEF's as my surround speakers replacing my Polk towers because the KEF has more transparent highs. I bought Focal 1028be's as my main speakers displacing the KEF's. Definitely replace both left and right tweeters. You want matched drivers.
What I like in the kef 104/2 treble is their suave tonality without making too much, a forgiving tweeter, at least for my taste ! For sure metal dome have more détails and "presence" (?)... not sure it gives a better tonal balance (I am asking yet ! having my main with aluminium dome...btw certainly less smooth than Be tweeters!)
I ended up going with the Morel tweeters. I am currently using my Magnepan 1.6's as I think they sound more to my liking. The Kef's are good speakers but I havent found a tweeter that matches up good yet. I even tried a pair of Vifa XT25TG30-4 tweeters but ended up putting the Morels back in.
just thought I'd come back with an update.
it took a while but midwest finally got some more tweeters in stock.
i got a pair and put them in my kefs.
all i can say is i knew the tweeters needed replacing but i never realized how much until i put the replacements in.
(mine were purchased new in the mid 1980s)
wow, it's like welcoming back a long lost friend ...
thanks normd for the lead to the replacements; i appreciate it!
🙂
mlloyd1
it took a while but midwest finally got some more tweeters in stock.
i got a pair and put them in my kefs.
all i can say is i knew the tweeters needed replacing but i never realized how much until i put the replacements in.
(mine were purchased new in the mid 1980s)
wow, it's like welcoming back a long lost friend ...
thanks normd for the lead to the replacements; i appreciate it!
🙂
mlloyd1
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cool,
I re ferrofluided my T33s (old one: kef 104/2 ref mono amplified version) ...but saw one of the dome was not stiff anymore ! 😱
Has anyone some idea please how to give a new surface treatment to recover the necessary stiffness (and proofness I assume as it is a fabric dome!)... but without wasting the genuine T33 : I can push with a finger the top of the dome of one of the T33 more than easily to a "Satori tweeter shape"(but the dome comes back to the otiginal shape...it has just lost his surface treatment with the time ) while the second tweeter is stiff enough ( assume it had the double coating treatment in factory, lol) to keep its dome shape just getting down the surround.
Thanks a lot in advance if any inputt on how to solve this issue 🙂
I re ferrofluided my T33s (old one: kef 104/2 ref mono amplified version) ...but saw one of the dome was not stiff anymore ! 😱
Has anyone some idea please how to give a new surface treatment to recover the necessary stiffness (and proofness I assume as it is a fabric dome!)... but without wasting the genuine T33 : I can push with a finger the top of the dome of one of the T33 more than easily to a "Satori tweeter shape"(but the dome comes back to the otiginal shape...it has just lost his surface treatment with the time ) while the second tweeter is stiff enough ( assume it had the double coating treatment in factory, lol) to keep its dome shape just getting down the surround.
Thanks a lot in advance if any inputt on how to solve this issue 🙂
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I am currently using a pair of Infinity High Output Polycell tweeters with a resistor in parallel to reduce the output. They are the best match that I have tried so far. I saw that Midwest had a new shipment in, so I think I'll order a pair and give them a try.
seadoo,
based on what you've said about the morel tweeters you've tried, you may end up using a resistor to reduce the output for the midwest tweeters also if you try them.
i'm still listening to various recordings to see that the tonal balance matches my preferences. so far, i'm happy, but have only listened to a few CDs and LPs.
I may yet change my mind and pad the tweeters down a bit, but i don't think so right now.
I wish I could get kef to come to my house with their equipment and measure them, so I can tune them up to be JUST like they were when they first came home.
🙂
mlloyd1
based on what you've said about the morel tweeters you've tried, you may end up using a resistor to reduce the output for the midwest tweeters also if you try them.
i'm still listening to various recordings to see that the tonal balance matches my preferences. so far, i'm happy, but have only listened to a few CDs and LPs.
I may yet change my mind and pad the tweeters down a bit, but i don't think so right now.
I wish I could get kef to come to my house with their equipment and measure them, so I can tune them up to be JUST like they were when they first came home.
🙂
mlloyd1