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Ergo Edition X

And I thought being a new electronic wizard you'd have gone for the transform! But no I think you are right, I think too much effort becomes a little unhealthy for the amp and speakers.

I hope you don't need best of both drivers and decide to put another amp and XO in the system ;)
 
There is a cheapskate half way house to LT that is often worth trying, especially you have some spare gain in the low frequency channels.

This is just a simple passive shelving filter, set so it gives 6dB/oct cut above say 20Hz, with the upper corner at say 50Hz. This will give about 9dB of boost at 20Hz, which would get you close to flat.

To do this, you just need two resistors and a capacitor. Place R1 between source (LF output of xover) and LF power amp. Connect R2 and C between LF amp input and earth.

Something like 10K for R1, 5K (4K7 ?) for R2 and 0.47UF for C should be close enough to be worth trying.
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              __ 0.47U
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Thanks for the shelving idea, PD. Wouldn't the corner frequency depend on the impedence of the active XO and amplifier? It seems too much hit or miss for my need for certainty, whereas I have used the Scan-speak 25W before, and I know it'll get me the extension I'm missing.

I hope you don't need best of both drivers and decide to put another amp and XO in the system
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Not likely. I'm more likely to build a whole new loudspeaker system with a pair of 15" woofers. Anything more than three ways is overkill. ;)

James
 
Hi James. Have you measured those P/l woofers to see if their actual parameters match the published specs?
 
RustyB said:
Hi James. Have you measured those P/l woofers to see if their actual parameters match the published specs?
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No. I'm not really set up to measure T/S params accurately. Could you use the 830669s in your stash or foreseeable business??

James
 
Not really. I'd seriously suggest getting hold of WT3 from Parts Express, it's a really useful and easy to use tool.

Strictly speaking, one should buy woofers, measure them, then run them in with a Sig Gen, then measure again, before settling on a cabinet design. Tedious, I know, but good insurance.

I noticed some variation between the parameters in the Mad Cat and those BBPro coughed up, could just be complementary of course.
 
RustyB said:
Strictly speaking, one should buy woofers, measure them, then run them in with a Sig Gen, then measure again, before settling on a cabinet design. Tedious, I know, but good insurance.
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I recognise this is particularly important for reflex enclosures, but sealed boxes are much more tolerant of variations. It's usually a trade-off of one param for another and the correct box volume rarely changes. It's another reason why I like Scan-speak. Their published specs are generally reliable.

James
 
Not always. The Vifa PL26's I have require a significantly larger box than you would build based on the published parameters.
 
James said:
Thanks for the shelving idea, PD. Wouldn't the corner frequency depend on the impedence of the active XO and amplifier? It seems too much hit or miss for my need for certainty, whereas I have used the Scan-speak 25W before, and I know it'll get me the extension I'm missing.
Click to expand...

The output impedance of the crossover is low, way less than 100 ohms, so the uncertainty it gives is tiny - much less than 0.1dB. The power amp input impedance is in // with the output resistance, and I have assumed that it is reasonably high compared with 5K; if not you can increase R2 appropriately so the parallel combination comes close to 5K.

Because this is all 1st order stuff, with no gain or resonant components in the system, it is very forgiving.

I'm not suggesting this as the ultimate long term solution, but it is something that can be tried in minutes, to see if this class of idea, or possibly a proper LT, scratches your bass itch.
 
RustyB said:
Not always. The Vifa PL26's I have require a significantly larger box than you would build based on the published parameters.
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The PL26s are *similar* to the W26-09-08 I used for the PFM-Specials, no? If so, the Vb for Qtc of 0.7 should be around 45L. Based on the published spec, this seems to be the case. Have you measured significantly differently?

James
 
PigletsDad said:
I'm not suggesting this as the ultimate long term solution, but it is something that can be tried in minutes, to see if this class of idea, or possibly a proper LT, scratches your bass itch.
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Thanks again, PD. I'm generally less comfortable with electronic intervention lest I blow something up. It took me long enough to muster the courage to put together the P09/P05 AXO/PSU. Since I already have a pair of Scan-speak 25W woofers on their way, I'll try that first before the LT or pseudo-LT treatment.

James
 
The Peerless 830669s are out and the Scan-speak 25W8565-00s are in.

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There is absolutely no doubt the real McCoys reach deeper into the mix. I've been listening to a bunch of music I bought in the last few months and hearing nuances I've never heard before. The extra half-octave has added the gravitas that I've missed with the Peerless. I've had to turn down the trimpots on the MF/HF active filter to compensate for the lower sensitivity of the Scan-speaks but that's about all.

Whilst there is no denying the 12" woofer provided a real presence, the slightly PA quality of the rolled-off bass response was not worth the compromise. I only wish Scan-speak would make a 12" version of the 25W.

At last, the E-Xs now sound like the full-range loudspeaker I intended.

James
 
I advertised these for sale at a local online auction site for NZD3,000. There were plenty of interest/watchers and positive comments. In the closing two days, I thought I'd better connect everything up to make sure they worked. I also thought it'd be a good idea to internalise the passive crossover, which looked a little silly sitting in a little wooden box behind the towering monoliths. Together, they had not been used for the best part of 18 months, maybe more. I certainly couldn't remember how they sounded. The E-IIIRs had been firmly in place all that time and sounding superb.

Another reason for internalising the passive crossover was to parallel the MF/HF sections. Previously, I had configured them as separate filters; each driven by an amplifier. I have six channels of Densen comprising 1 x B-340 and 2 x B-350, which was how the E-Xs were powered the last time. As a minimum, they would need two stereo amps or one quad amp, which is where the B-340 comes in nicely.

After a weekend of work and many leftover Neutrik connectors and scrap wires everywhere, I hooked the E-Xs up to the 60W x 4 B-340, which had the same front end (B-400XS) and control (C-21 / active crossover). The result seriously questioned my sanity for wanting to sell them at any price, let alone the relatively paltry sum of NZD3K. This pair of loudspeakers took me the longest time to build (about two years, including the active XO design), is the purest design purpose dictating form, and there isn't another pair like them in the world, now and forever.

Thankfully, no-one had placed a bid. So I raised my reserve to NZD10K to avoid someone's gain and my insane loss. No-one in their right minds would pay that amount for a pair of DIY loudspeakers, which is just as well. The E-Xs are not for sale; not while I still have my listening faculties and the full complement of marbles in my head.
 
Hi James
So what is it about them, I am working on something similar a 3 way with passive mid/treble and active bass crossovers powered by 4 hackernaps it's a version of Troels ellam flex3w.
I have 4 scan 25W which I am going to try 2 in an undersized box with linkwise transform.
Geoff
 
Compared directly to the E-IIIRs, with a similar Scan-Speak 25W woofer (-01 variant, rather than the -00), the E-X offers a greater sense of weight. I think this is partly a function of boundary loading. The wide baffles also seem to make the loudspeaker more sensitive to toe, and the expansiveness of acoustic illusion is more easily and accurately dialled in to the correct size. The E-IIIRs have a slightly more transparent midrange, but that is more likely due to the superlative Seas M15CH001 trumping the Seas P18RNX. I may consider a change of midrange driver from the Seas 18cm range.

Other than that, I will keep these in place for a minimum of a few weeks to see how they re-establish themselves. I also haven't fully optimised their room positioning. That's a job for next weekend.
 
I've decided the E-X, E-IIIR and E-IXs are not for sale.

My next project is to internalise the E-IIIR and E-IX crossovers, and finish the PFM-SIIs. I borrowed the latter's tweeters for the last pair of E-IXs I shipped.
 
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