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Tweeter Recommendation?

K

Kevviek

Active Member
Hi all…I’m restoring these Micro-Acoustics FRM-3 speakers, and thinking of swapping out the tweeters.

I bought them not knowing anything about the brand, but liked that they were a bit unusual, and on demo they sounded much better than I was expecting.

As it turns out they have had the woofers replaced with Scan Speak 22W/8534G units, with a simple first order crossover at 2500Hz.

They do sound good, but I figure the highs could be a bit crisper and given the quality of the woofers it could be worth a tweeter upgrade. I’m assuming these are originals but couldn’t find any info other than they were made with Matsushita units. Mine are marked F-4022.

Before I dive into further analysis (the peak at 2-3k is a bit troublesome) I was wondering if anyone knows of a good match already. Something that would fit with no modifications would be ideal, but as a starter something that suits a cross at 2.5kHz, woofer sensitivity is 89dB. Outer edge of the frame is 90mm, inner is 60mm and mounting holes 74mm.


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That's an 8 ohm, yours is a 4 ohm, why not keep the existing tweeter, and investigate the crossover tweeter capacitor it would be cheaper to replace and might solve the issue and probably best to do it anyway. Just an option.
 
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The Scanspeak driver you have deserves something more. To do it right, select an appropriate tweeter like a Scanspeak ring radiator. It should be able to crossover in the 1200-1500Hz range with a 2nd order LKR filter. That same 2nd order filter should work with the woofer as well.
 
John3655 said:
That's an 8 ohm, yours is a 4 ohm, why not keep the existing tweeter, and investigate the crossover tweeter capacitor it would be cheaper to replace and might solve the issue and probably best to do it anyway. Just an option.
Click to expand...
It already has new high quality caps
 
Can't help on tweeter recommendations, but those are really nice looking speakers and reportedly sound better than the Bose 301 speakers they were modeled after (a lot of people like to trash Bose, but the 301's sounded quite good in period).
 
Mr Boochie said:
How about a dome tweeter?
Click to expand...

That's my thought. Here's one of my go-to tweeters, that always seems to work in 2-way systems:

www.madisoundspeakerstore.com

SEAS Prestige 27TFFC (H0881) Textile Dome Tweeter

SEAS Prestige 27TFFC (H0881) Textile Dome Tweeter. High-quality tweeter in stock. Crossover and system matching advice available. Contact Madisound.
www.madisoundspeakerstore.com www.madisoundspeakerstore.com

BTW: I suggested the smaller, truncated-flange version of this tweeter family before, because it could fit into the original bracket. If one were willing to modify or replace that bracket, this is a much better solution. It's recommended specifically to use as a replacement in the Dynaco A25, which has an effective crossover to a 10" SEAS or Scan-Speak woofer (depending on the age of the A25 system) at about 1500 Hz.

In fact, if you get the tweeters from Madisound- they can likely provide, for an additional fee, a custom crossover design tailored to this exact driver combination, using LEAP/LMS. They sell both SEAS and Scan-Speak, so they have data on them both. That would be a no-brainer, it would work fine.

Regards,
Gordon.
 
I believe that is true, and it may have sunk the company.
It isn't as if a tweeter than can be directed in a specific direction is a miraculous invention, and there have a been companies that had such things, but somehow managed not to be sued by Bose, who is uncommonly litigious and (bizarrely) managed to claim ownership of the idea - patent courts are odd, as Ariston found when Linn sued them for using their using their own (Ariston's) design.
I had a pair of those MAs, with the foam surrounds replaced with red velvet(!). They were very nice sounding, better than the speakers they looked similar to (which may have been the problem from Bose's point of view).
I wonder if that midrange peak is a result of using a different (even if supposedly better) woofer. If 'better' means a more extended high end, you will have more midrange energy than designed for.
 
Nat said:
I believe that is true, and it may have sunk the company.
It isn't as if a tweeter than can be directed in a specific direction is a miraculous invention, and there have a been companies that had such things, but somehow managed not to be sued by Bose, who is uncommonly litigious and (bizarrely) managed to claim ownership of the idea - patent courts are odd, as Ariston found when Linn sued them for using their using their own (Ariston's) design.
I had a pair of those MAs, with the foam surrounds replaced with red velvet(!). They were very nice sounding, better than the speakers they looked similar to (which may have been the problem from Bose's point of view).
I wonder if that midrange peak is a result of using a different (even if supposedly better) woofer. If 'better' means a more extended high end, you will have more midrange energy than designed for.
Click to expand...
Yeah....they also sued an audio magazine because they didn't like the critique on the 901's.

I now have a bit of a dilemna for these speakers. The scan speak drivers are 8 ohms and the original tweeters are 4 ohms. After finishing the cosmetic restoration I've put them in my normal listening area and although they do sound very clear, with familiar material they are very lacking in bass. All the wiring is correct and I'm now wondering if it's just because the tweeter is higher efficiency. There is a custom crossover and I assumed whoever put the new drivers in knew what they were doing.

Anyway, time to pull them apart again and measure the inductors to see what is going on. I like the idea of putting dome tweeters in if I can get the bass sorted and I have some SEAS H253 that I could try before buying the 27TFFC's. From rough measurements the cabinet is about 30 litres with dual 50x70mm ports.

The alternative is just to put a cheaper woofer in that is more aligned to the tweeter, and enjoy the nostalgia value.
 
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Kevviek said:
Yeah....they also sued an audio magazine because they didn't like the critique on the 901's.

I now have a bit of a dilemna for these speakers. The scan speak drivers are 8 ohms and the original tweeters are 4 ohms. After finishing the cosmetic restoration I've put them in my normal listening area and although they do sound very clear, with familiar material they are very lacking in bass. All the wiring is correct and I'm now wondering if it's just because the tweeter is higher efficiency. There is a custom crossover and I assumed whoever put the new drivers in knew what they were doing.

Anyway, time to pull them apart again and measure the inductors to see what is going on. I like the idea of putting dome tweeters in if I can get the bass sorted and I have some SEAS H253 that I could try before buying the 27TFFC's. From rough measurements the cabinet is about 30 litres with dual 50x70mm ports.

The alternative is just to put a cheaper woofer in that is more aligned to the tweeter, and enjoy the nostalgia value.
Click to expand...
On the Parts Express page you can choose 4 ohm. Also you can sort from low price to high price. Depends how much you want to spend I suppose. This one can be crossed fairly low if that is needed. Costs a bit more...
www.parts-express.com

Dayton Audio RST28F-4 1-1/8" Reference Series Fabric Dome Tweeter 4 Ohm

Dayton Audio RST28F-4 1-1/8" Reference Series Fabric Dome Tweeter 4 OhmThe Dayton Audio RST28F-4 silk dome Reference Series tweeter offers exceptional efficiency from 1,400 Hz to 20,000 Hz with an extremely natural and dynamic sound. This unique 1-1/8" silk dome and a state-of-the-art Ferrofluid...
www.parts-express.com
 
Update...please bear with me:

I tried some different tweeters, I had some Vifa D20TD-05-08, installed them instead of the Matsishuta cone tweeters and they fit perfectly but sounded worse, not better. So, given the style of the original speakers, I think I'll keep the cones.

Next step, I measured the crossover components. I know that I need to model properly to see what's really going on, but in general...
- the cap is 3.3uF: in series with the 4 Ohm tweeter means around 10kHz
- the inductor is 0.3mH: in series with the woofer means around 4kHz

So there is opportunity - with the right crossover - for these to sound much better than they do, but...

From what I know of the Scan Speak woofer, it is harsh above 1kHz and needs to be crossed lowish. So it will only be useful if the tweeter can run that low. But in any case I think the Scan Speak woofer is wasted in this box, so I'm going to take it out and use it for something else.

Options I have already on the shelf to use as the woofer:
- Peerless 8"/8 Ohm woofer, unknown model number,
- SEAS P21REX 8 Ohm woofer, looks to have similar response to the Scan Speak. So would also need to be crossed around 1.5kHz maximum

** I have not been able to find any guidance on best crossover frequencies for cone tweeters, but I assume 1.5kHz would be ok.

The guidance I'd like:
- if I use 8 Ohm woofer, is it better to use an LPad or series resistor to make the tweeter appear closer to 8 Ohms and design the crossover to match, or just use a tool like this and leave both as is: 2/3-Way Crossover - K7MEM. I know I'll probably have to play with levels

Or should I instead try to find a suitable 4 Ohm woofer like this (budget version to suit a vintage cone tweeter): https://www.newark.com/multicomp-pro/55-3231/woofer-8-50w-30hz-to-2khz-86db/dp/43W7872 and design the XOver for 4 Ohms?
 
Might I suggest you take Gordon's suggestion and check with Madisound? I've found them to be very helpful, and while they may charge for designing the crossover, if you use drivers from them, they probably have suitable designs allready. Meanwhile, buying and trying random drivers and crossover components may end up costing much more than simply paying for knowledgeable guidance.
Of course, if your real goal is to have fun trying things out and learning as you go, you are already on your path.
 
Hi @Nat. I decided the Scan Speak driver is not suitable for these boxes and I've got a target design for it via the Madisound website, it's this driver: Scanspeak 22W/8534G00 Discovery 8" Woofer & this design Bookshelf-3WC.

The questions I have relate to getting a new woofer and crossover to match the original Micro-Acoustics 4 Ohm cone tweeter, for which there is no information against which to design a crossover properly. So I'm seeking opinions for the cheap and cheerful path :-)
 
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