Being an 8 ohm tweeter you could (probably) get away with a 22 cap without having an effect on the response at 1200 Hz. I used a Clarity CSA for the protection cap on the one I did, wasn't willing to spend on the 2 Mundorf Supremes I would've needed to get to 32 ish, would've been like $150.
I haven't done the build yet using the AE TD8M. I did hear it in another guy's 2 way, he used it with a Transducer Labs tweeter in a pretty deep waveguide. If I recall, it was crossed somewhere around 1.5khz?? But I fell in love with that midwoofer when I heard it, very natural and articulate sounding.
The 18M sounds very similar to the 18W, which I've always loved. When I purchased the 18M I planned on using it with a 93 db, 15" woofer so I needed the extra efficiency from the M. If I didn't need the extra efficiency, I would've probably just went with the 18W just so I had the option to cross lower than 300 Hz if I wanted to because they sound so similar.
All that said, based on a lot of experience with the Scanspeak 18 Revelator series, and the limited listening session with the AE TD8M, I would pick the TD8M as the winner in the midbass/midrange category. I think it sounded more realistic, the 18 can be a smidge laid back or maybe "bloomy" sounding in comparison. Not sure how better to describe it lol. And don't get me wrong, I could easily live with both of them, but if I had to pick one, based on limited listening I'd probably pick the TD8M. My opinion might change after I spend a lot of time with it though.
Greets!
Not sure I follow, so what do you mean? Did I screw up the math somewhere?
Hi GM
IIRC the CTC should be measured from mid to mid center and not between mid and tweeter for an MTM, giving twice the distance and therefore half the maximum crossover frequency.
Regsrds
Charles
IIRC the CTC should be measured from mid to mid center and not between mid and tweeter for an MTM, giving twice the distance and therefore half the maximum crossover frequency.
Regsrds
Charles
Greets!
OK, thanks, so I've been misunderstanding this AES paper with the understanding that the math means nothing to me, so assumed the 'd' dim. in the first two figures were the same?
Also, out of curiosity I looked up D'Appolito's THOR TL and its MTM is nearly a WL between the tweeter/woofer, so clearly I'm (we?) are missing something.
OK, thanks, so I've been misunderstanding this AES paper with the understanding that the math means nothing to me, so assumed the 'd' dim. in the first two figures were the same?
Also, out of curiosity I looked up D'Appolito's THOR TL and its MTM is nearly a WL between the tweeter/woofer, so clearly I'm (we?) are missing something.
I only ever use active crossovers, and my 215W per channel MC2 amps have switch on delay so the problem does not arise for me! Sorry I cannot help as my brain cannot be picked on passives! I have used massively overpowered amps on the TPLs on occasion on drivers which are still working perfectly in my friend's system. I have moved on from the Beymas to BMS coaxials for higher output but they remain the best HF driver I have heard.
It would cost me a lot more to lose the subs due to a fault compared with the TPL so I trust to chance by having no second-level protection for them.
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You've probably chosen a larger value so that it doesn't affect your response. I can see potential benefits in making it smaller.
Hello Mr. Klinky
Regards
Chalres
So you would prefer the TPL over a BMS coax for a loud HiFi application ?
Regards
Chalres
Indeed. The TPL is a resistive 5 ohm load, and 37uF was implying a 1st order xo of 850Hz IIRC, which was far from my initial target of 1.7-2kHz. Now I'm using lower digital xo, though.
Could you elaborate on the potential benefits of going with a smaller cap?
Reduced interference from DC related effects like thumps, can use a smaller single unit, easier to find capacitors in smaller values.
Make it small enough to be a part of your rolloff, your DSP can get you the same response with or without the cap. In fact you can leave it in place permanently, even when you measure.
Make it small enough to be a part of your rolloff, your DSP can get you the same response with or without the cap. In fact you can leave it in place permanently, even when you measure.
Thank you. What would be the math involved? I believe a 2uF cap would imply a 1000Hz xo corner frequency for this tweeter, or at least that's my understanding. 20uF would be 1600Hz.
You could get 3 or 4 different NPE caps and try them for cheap- like a 15, 18, 22, and a 25 for example. Once you find the value that works the best, then spend on a good poly cap. The math is useful but only to a point.
Or get a 15, a 2, a 5, and a 10 and stack them until you get the value you're after, keep them for future experimenting.
Math? You could in theory use any capacitor value you wanted. It is logical to place it near the current rolloff but there are many small factors that you might consider one day when you have nothing else to do. It will all come together when you find the right filters to use and maybe after that you might decide to try a different value but I don't expect so.
Your approach will depend on the way you manage your cross. There are many ways to do it. If you measured with a cap in place you would simply adjust your processor to meet your main target response. If you sim the capacitor instead, you can subtract it from your target response or add it to the response you have for the driver.
If you aren't using a target response you can select a capacitor that rolls off at the same frequency as one of the processor filters and then change that filter to be one order less, and compensate for changes in the filter knee.
Sorry for the delay. I wasn't implying advanced math 🙂
A first order xo is obviously a cap in series with the tweeter. The size of the cap = 0.159/(tweeter resistance x crossover frequency). Using a 37.4uF cap in series with a 5 ohm tweeter results in a 1st order xo point starting at 850Hz. I used this as protection cap. Beyma recommends this tweeter from 1.1kHz with 2nd order xo, so I took 850 to be low enough to mildly affect response while being high enough to protect the tweeter. Pure guessing on my part.
I did measure the tweeter with/without cap and could see the 1st order xo impact. Of course this was done at low SPL to avoid damaging the tweeter without protection.
The digital xo is established above 850Hz, currently at 1300Hz, so the cap has reduced impact. I do work with a target curve so any influence from the cap is compensated by DSP/target curve.
Seems I have been on the right path. I will try smaller cap values with existing cheap caps to decide which size and then buy good "audiophile" caps to hopefully get better sound. Which caps should I look into? V-Caps OIMP come in 20uF (1.6kHz xo too high), ClarityCaps have been mentioned but have many lines (PUR, CSA, MR, etc that confuse me), or others? V-Cap ODAM are a bit too expensive for me.
BTW @mattsk8 have you decided to move forward with your project? Please keep us posted!
I have to button up a build I'm currently working on, hopefully have that done in a couple weeks. After that's finished I'm torn between starting the Beyma/18M/22W WMTMW... or I also have the drivers for a TMWW using (2) AE TD10H, AE8M, and a Faital Pro HF10AK tweeter.
One of these builds will also be active using Pascal/Marani DSP plate amps. Leaning towards using those on the Beyma build just because I think the DSP will be more beneficial on that tweeter.
Thanks for the update. Is the choice for AE8M+HF10AK instead of TPL-150 driven by expected synergy, or in other words not the best fit between TPL and AE8M?
Either tweeter would probably work well over the AE8M, that's the build I originally bought it for. And maybe I should do that build first (TD10H + TD8M) and just try both the Faital Pro HF10AK and the TPL150 and see which I prefer. Instincts tell me I'll probably pick the HF10AK but not sure, both have a very similar range but I think the HF10AK has a better upper range than the Beyma. Take that with a grain of salt because I've never worked with either.
Edit: I think you just helped me decide. I'll do the AE build active and try both tweeters in a test cabinet. Then once I choose a tweeter I'll finish the cabinets.
Then... I'll try whatever tweeter didn't work passive in that next build using the 18M. Because that build has a lot more options for tweeters.
Hey Matt.
Was wondering how your build has evolved and wanted to share that I am now driving my TPLs directly from my 45-type SET amp without protection caps and the difference is big, in a good way 🙂
In an earlier post you mentioned you might consider going active, so wanted to provide the input. Of course this is a bit risky and I explored it a bit, looked into good protection caps to upgrade what I had, and concluded a replacement diaphragm cost less than a good cap ($130) so took the plunge. No issues at all...so far...
Cheers!
Was wondering how your build has evolved and wanted to share that I am now driving my TPLs directly from my 45-type SET amp without protection caps and the difference is big, in a good way 🙂
In an earlier post you mentioned you might consider going active, so wanted to provide the input. Of course this is a bit risky and I explored it a bit, looked into good protection caps to upgrade what I had, and concluded a replacement diaphragm cost less than a good cap ($130) so took the plunge. No issues at all...so far...
Cheers!
Sorry for the late reply - missed your response.
Yes. Absolutely. (Assuming that the higher crossover frequency is acceptable in your application).
Hey. I got hooked on this MTM dipole idea too.
Now need to decide if 18wu 8747 would create good synergy with Mundorf 25d. All run from fa253. Have quite live room and it's not too big.
Had you tested your idea already? Any lobing issues?
Now need to decide if 18wu 8747 would create good synergy with Mundorf 25d. All run from fa253. Have quite live room and it's not too big.
Had you tested your idea already? Any lobing issues?