P-Audio C18 650EL

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JohnG
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#1 P-Audio C18 650EL

Post by JohnG »

Is anybody familiar with this brand and will it be useful as a suitable bass driver for a OB ?
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IslandPink
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#2 Re: P-Audio C18 650EL

Post by IslandPink »

Looks very heavy duty with high cone mass. Are you going to use this with ESL57's ?
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chris661
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#3 Re: P-Audio C18 650EL

Post by chris661 »

The brand's okay. I have one of their top-end 21" subs which goes out for party rentals.

With regards to that particular driver, it looks reasonable. Xmax is a bit on the low side and Fs is a bit high, but the demodulating rings should keep distortion low.
I'd probably add some mass to the cone to get Fs down to 30Hz ish, which would also push Qts up. That'd gain some LF extension at the expense of upper-band efficiency.

Chris
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#4 Re: P-Audio C18 650EL

Post by IslandPink »

While what Chris says is useful, I think he would typically use drivers at much higher SPL levels than you would ever need to augment the 57's. I would much prefer something like the Eminence Beta 15 for this application myself. A bass driver that's designed for 650w ( or is it 1200W ? ) will likely sound quite grey & lifeless at low dB levels. I know those P-Audio's look cool but it's got nothing to do with how they'd sound.
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JohnG
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#5 Re: P-Audio C18 650EL

Post by JohnG »

I do not intend on using these or any other bass drivers as a permanent partner with the 57's. I am looking to build a OB so I am casually looking into affordable bass drivers, and these ones appeared.
I was wondering how they would compare to a Beta, but it seems the Beta is still the recommendation.
As part of the learning and R&D, I will play with the bass drivers and the the 57's, I,m just curious as to what will happen when a OB bass extension is added.
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#6 Re: P-Audio C18 650EL

Post by chris661 »

IME, to do OB bass properly, you need some serious LF capability.
I set up some parts of my current PA system as an OB, and with a 15" a side EQ'd flat to 25Hz, cone excursion was hitting 30mm p/p when the program material demanded low bass. It was at somewhere near "demo levels", ie, too loud for conversation. The sound itself was pretty good. Some of the best bass I've heard, but the mid-high (dipole mid handing over to a horn-loaded HF) wasn't right. I attributed that to having a weird polar pattern through the crossover frequency. While the front side measured flat, the stuff coming back from the room had some serious spectral imbalances.

Anyway, just because a driver is rated for hundreds of watts, doesn't mean it'll sound bad driven quietly. It just means it can dissipate heat if needed. I'd argue the driver in question should be more than a match for the usual Eminence drivers, which have basic ferrite motors.

Chris
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#7 Re: P-Audio C18 650EL

Post by IslandPink »

chris661 wrote: Wed Oct 18, 2017 7:54 pm Anyway, just because a driver is rated for hundreds of watts, doesn't mean it'll sound bad driven quietly.
So far in my experience this has always been the case. I don't agree with you and your arguments & numbers betray the sort of listening you're used to - but I don't have much energy to argue any more at the moment. I just want to make sure that John doesn't waste his money.
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chris661
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#8 Re: P-Audio C18 650EL

Post by chris661 »

Hi Mark,

It seems you think I routinely listen at excessive levels, and that really isn't the case. Given that I'm in a semi-detached house, the speakers built into my laptop go as loud as I play my music from the stereo. No, really. That said, I do believe that a stereo should be able to play any music at pretty much any (sensible) volume, so I like to build in some headroom.
The OB I mentioned was at demo levels, with peaks of over 100dB. That's not especially loud in the grand scheme of things, but it certainly isn't quiet either. At relaxed levels, the cones weren't moving so much.

Given that the Eminence drivers are also rated for a few hundred watts, how might they be different to this driver?

If you've decided that my opinions aren't worth anything because I'm involved in live sound, that's okay. I'll save my energy.

Chris
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#9 Re: P-Audio C18 650EL

Post by steve s »

My bass drivers are fane 18xb they work fine with less than a watt...
They have a first order low pass around 250hz, the next speaker up is critical, a wide band large magnet speaker around 10-12" arguments the bass and provides upper bass detail and midrange just avoid drivers that peak too much here.
Then theres just the 2k upwards to sort.
But there are lots of other ways to do it.....? Some better than others
Lower efficiency speakers are easier to build with. But the result is generally a speaker with less realism. But you may have to double up the bass drivers or eq them
If you want economical speakers buy the better 'used ' drivers...
It's a slippery slope, but for me after spending more than 20 years building speakers I've reached point I want to be...( till I hear something better) I just want to build another identical pair for my music room to replace my white lighthouses
Ali's speakers are a very good step to open baffles in my view
But a bass driver to use with statics is a difficult ask, you need real acceleration to keep up.. so cheap speakers are out... but you have the advantage of being able to filter the higher frequencys and still be left with comparable efficiency.
Best of luck..
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#10 Re: P-Audio C18 650EL

Post by JohnG »

I am thick when it comes to electronics and not learned like the experimenters in this community
.
I am looking for a bang for buck bass driver, and every so often a pair surface well under their new price. Hence the enquiry, all replies are very welcome.
I do not intend on producing a sub woofer to be a permanent partner to the 57's, but a temporary partner to trial while I go through the motions of building a OB from the bass up.
I will at a later date put the Audax HD-3P Gold Piezo in with the 57's as a trial and also attempt to use it on the OB's.
I suppose it is now time to make a few winter by the fire projects to make the most of the long nights.
As said before Ali,s crossover choice is appealing to me for the very user friendly interface.

I hope to drive these speakers trials with a 25 watt PP 845 monoblock and a 25 Watt stereo K5881 amp.
So keep on replying, I,m all ears.
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Ali Tait
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#11 Re: P-Audio C18 650EL

Post by Ali Tait »

I don't think you will get much more bang for buck than the Eminence Beta TBH.

Lots here have used them and we know they sound good.
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IslandPink
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#12 Re: P-Audio C18 650EL

Post by IslandPink »

chris661 wrote: Wed Oct 18, 2017 10:06 pm Given that the Eminence drivers are also rated for a few hundred watts, how might they be different to this driver?
The Beta 15a is rated 300W (RMS) with an Rms of 1.6. This is significantly better in my books to the higher-power drivers discussed.
chris661 wrote: Wed Oct 18, 2017 10:06 pm If you've decided that my opinions aren't worth anything because I'm involved in live sound, that's okay. I'll save my energy.
It's not quite that bad - I just think the advice needs to be tailored to the problem. The ESL 57's are some of the most subtle speakers ever made - they respond to low-level signals like very few speaker units. They need a bass solution that's suited to the task. OB is a very good start because of the low group-delay, but I think the bass driver needs to be a lower cone mass and lower mechanical damping. I would choose the Supravox 285 or 400EXC of course, if money was no object :D
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chris661
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#13 Re: P-Audio C18 650EL

Post by chris661 »

Yep, in terms of price-to-performance, the Eminence 15"ers are the way to do it.
I'd expect the 18"s in question to be better overall, since there's a powerful motor and more Xmax (ie, a bigger linear region for the driver to work in), but they're also considerably more expensive than the Eminence drivers.

In response to Mark's post that's just appeared, I see your point. I think that, for low bass frequencies, it's not such a problem. Depends if it needs to be a dedicated subwoofer (running below 80Hz or so) or a woofer running up to a few hundred Hz. For the former, I expect the 18" in question to be fine. For the latter, the heavy cone might start getting bendy past 200Hz.

Chris
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