Ergo Number Nine - Adventures in Micromonitor Design

[Richard Nichola]

I think mine went from 45Hz to 35Hz. Spec is 30Hz and I just think they take a lot of playing to get down to that frequency. Oddly enough my Scanspeak 97000 tweeters were within 5 Hz of their published spec of 500Hz right out the box.

 

[James]

Sounds like he's got a pair of mids by mistake.

I've had a pair of Scan-speak mids, but these play music like proper midbass drivers. I think I had a slightly dodgey measurement set-up. This weekend, I'll take both free-air measurements and baffled readings if fs is close to 30Hz.

James

 

[RustyB]

Most likely.

I am reminded, however, of Troel's "Mini-Strad" design, using Seas CA22's. He found that the measured T/S parameters were so far out of whack that, had he built the cabs prior to measuring the drivers, they would have been useless.

 

[James]

After playing some music loudly through them yesterday and today, I took a fresh set of measurements. What a world of difference! The 15W mid-woofer now has its resonance at around 65Hz in-box, which is not far off the mark for a predicted fb of 60Hz for a Qtc of 0.707. I'm sure more running would soften the suspension further and reduce the fb. Here is the impedance graph as I measured it this afternoon.

With much better and cleaner data, modelling the perfect XO for the E-IX should be a breeze. Or so I thought. I was aiming for a second-order Linkwitz-Riley crossover, but simply could not get the phase to line up even remotely closely. I tried crossing over from as low as 1,800Hz up to 4kHz, but it just wouldn't cooperate. Then I remembered the exact problem with the E-IVs, and that required a 4th order crossover to get good phase alignment.

Some of you might think 4th order is just 2 order too many LCR components. If it was a text-book 4th order, then absolutely. But I managed to get away with implementing a 3rd order electrical on the LP filter and a 2nd order electrical with a zobel on the HP filter. This combination crosses the 15W to the MDT37 at 2,200kHz, and results in a 4th order Linkwitz-Riley symmetrical transfer. The XO is deceptively simple:

For even-order crossovers, a handy way of telling if the phase and drivers are aligned is to reverse the polarity of one driver. With perfect alignment, there should be a deep and narrow null where the sound cancels out at the crossover frequency. This is the exact result I managed to extract tonight with a little bit of LspCAD wizardry. A picture paints more words than I can type.

The transition from the mid-woofer to the tweeter is almost seamless, and the gentle roll-off beyond 10kHz complements the similar response below 80Hz. With room-gain added into the equation, these little babies would have no problems hitting a clean 40Hz or lower in a domestic listening environment.

I'll now take an inventory of the parts I need and send for an order to build the XO for both the E-IX and the revised E-IIIs tomorrow.

James

 

[James]

I've ordered parts today, but only for the free-space version. With any luck, my order should be here before the weekend and the E-IX would finally be complete. I'll validate the wall mount design at a later date. If anyone would like to build a pair of E-IXs, I'm happy for these plans to be used. Just start a new thread and I'll be happy to guide you though the building exercise.

James

 

[James]

Number Nine is ALIVE!!!

I'm gob-smacked, seriously. The little 8-something litre loudspeaker sound anything but small. My whole belief system that was based on the effortlessness of large loudspeakers may be destroyed forever. The three words I'd use to describe the E-IXs are:

Real - it's way past my bedtime but I couldn't stop playing music. The illusion of people playing music in my lounge has never been so tangibly, unequivocally, fabulously real. It's an old cliche, but I'm hearing not so much more detail, but more nuance and subtlety in phrasing and expression.

Coherent - I'm really bad at listening to lyrics, and most often prefer to simply enjoy the tune and tempo. With the E-IX, it's hard not to notice with almost perfect clarity what each performer was singing. Music just seems to make more sense.

Giant Killing - The 5-1/4 inch drivers totally surprised me with how much authority they lend to the bottom end. To put this into context, I think only the E-IIIs and E-Vs go lower, and very marginally so. Sure, the lowest octaves are not produced with the same degree of effortlessness, but you hear them perfectly clearly and in the correct proportion. I'm still shaking my head in disbelief.

I'll post a more detailed assessment later ...

James

 

[James Evans]

Fantastic work James. Have followed this thread in awe. I'm very tempted to get the plans off you and hoard them for a time when I've got some time to have a crack at these! Any photos of the finished article? Are the XOs internal or external?

James

 

[AshleyD]

Congratulations and very well done James. I think there is something very right about small loudspeakers, probably because small English living rooms need them!

I'll be starting on some soon, just got to build 6 raised panel doors for a bathroom project first, shouldn't take me long....

Well done agian,
Ashley

 

[Mr Tibbs]

Glad you like them James

it's hard not to notice with almost perfect clarity what each performer was singing. Music just seems to make more sense.

With the ES14s the above quote is also very true. Over the next day or two I bet you'll find that every instrument (save perhaps the lowest notes on bass) is more real. Now you can fully appreciate why I'm finding it hard to go back to the big 3-way speakers...

Mr Tibbs

 

[chiily]

Great news James. They look superb too.

So a set of these for the second system upstairs on the end of a NAP160 and a Starfish. Sounds like a plan to me.

 

[Fatmarley]

I'm not completely surprised about the mid-range but i am about the Giant killing sound - would be nice to get rid of my subwoofer.

I've been keeping an eye on this thread and i'm still up for building these, especially now that i have a more permanent job and will hopefully get paid for the last one (could make a few sets of these if i get paid)
Before i get started, i'd like to wait and see how you get on with the wall mount version.

One more thing - Being a natural tweaker, i'd like to build the crossover in a seperate box - Would that be ok? I wouldn't mess with the values, but i may want to try different capacitor types.

Nice one!
Matt

 

[vuk]

james.

well done! sorry if i have missed this somewhere, but didn't you make two sets of enclosures, one out of black american walnut (i think)? what happened to those? can i buy them off of you if not in use? i wouldn't mind giving this project ago, with a bit of help, of course.

vuk.

 

[James]

Hi Folks,

Fantastic work James. Have followed this thread in awe. I'm very tempted to get the plans off you and hoard them for a time when I've got some time to have a crack at these! Any photos of the finished article? Are the XOs internal or external?

James, the plans are in this thread and the XOs are designed to be in the cabinets.

I think there is something very right about small loudspeakers, probably because small English living rooms need them!

LOL! In that case you might want the wall-mount XO variant, which I've yet to build. The ones I have right now are designed for free-space and they do NOT leave you wanting in the lower octaves. I suspect they might be wrong for small English closets, ummm, I mean rooms.

Over the next day or two I bet you'll find that every instrument (save perhaps the lowest notes on bass) is more real. Now you can fully appreciate why I'm finding it hard to go back to the big 3-way speakers...

The E-X project may be shelved indefinitely, especially if I pull the E-III revision off with equal surprise.

I'm not completely surprised about the mid-range but i am about the Giant killing sound - would be nice to get rid of my subwoofer.

A sub is most definitely not needed with the E-IXs.

I've been keeping an eye on this thread and i'm still up for building these, especially now that i have a more permanent job and will hopefully get paid for the last one (could make a few sets of these if i get paid)
Before i get started, i'd like to wait and see how you get on with the wall mount version.

I'd love for everyone on PFM to build for themselves a pair of these. But I would really prefer it if these were not built and sold for profit, unless you'd like to pay me a royalty, of course.

One more thing - Being a natural tweaker, i'd like to build the crossover in a seperate box - Would that be ok? I wouldn't mess with the values, but i may want to try different capacitor types.

Externalising the XO would be fine. Should make very little difference.

... but didn't you make two sets of enclosures, one out of black american walnut (i think)? what happened to those? can i buy them off of you if not in use? i wouldn't mind giving this project ago, with a bit of help, of course.

Vuk, the ABW cabs are sitting quietly in my room. I've only just received some black grill cloth, with which I'll finish making the grill. I hadn't intended to sell them just yet, but I'll keep you at the top of mind.

James

 

[Fatmarley]

I'd love for everyone on PFM to build for themselves a pair of these. But I would really prefer it if these were not built and sold for profit, unless you'd like to pay me a royalty, of course.

Sorry James, i didn't mean it like that. Just meant i'm owed a lot of money.

Do you know if they are fully run in? or are expecting them to improve some more?

 

[Fretless Eric]

I'm going to re-read this thread with a serious eye to building. I'm just sorry I don't have the workshop capability (or AshleyD's helping hand, of course).

Well done James!

 

[James]

Do you know if they are fully run in? or are expecting them to improve some more?

They are gaining even more clarity and startleability by the hour. These are going to set the benchmark against which all future Ergos will be judged. I wish I had a pair of genuine LS3/5a handy for a direct comparison.

James

 

[hacker]

These are going to set the benchmark against which all future Ergos will be judged.

High praise indeed!

Nice one James. Even though it'll take me a few months before I start, I really fancy a pair of these bad boys.... BTW, got any crossover pr0n?

 

[James]

High praise indeed!

Nice one James. Even though it'll take me a few months before I start, I really fancy a pair of these bad boys.... BTW, got any crossover pr0n?

Thanks, Carl. The first remark my wife made when she listened to them was "wow, they sound a lot bigger than they look". She also felt they conveyed a sense of realism (if not the entire sense of scale or effortless compared to her then favourite E-IIIs) she hadn't heard before. I wished I spent more time listening to them critically during the weekend, but alas it was spent rebuilding the E-III Revision crossovers. The least I could do was give the E-IIIs a right of reply.

I have taken a few pics of the E-IX crossover, and setup during the measuring phase, which I'll post later on. It's just been manic trying to sort out two designs simultaneously.

James

 

[AshleyD]

I'm going to re-read this thread with a serious eye to building. I'm just sorry I don't have the workshop capability (or AshleyD's helping hand, of course).

Well done James!

G'day Eric, go for it, I reckon these little guys can be built with only one power tool, the router of course. BTW I noticed I still have your roundover bit, do you want me to post it on to you?
Ash

 

[James]

Here are some pics to show the E-IX during their XO development phase.

Far-field measurement at 1m. Proximity of E-IIIs doesn't matter because the gated measurement discounts any reflections, but this also limits useful readings below 500Hz. This is supplemented by nearfield measurements of the woofer, which is then spliced with the far-field one.

The microphone output is amplifier by this neat little 9V powered preamp.

One of my best recent investments, a Goot soldering station. Needed for hardwiring the drivers during the measurement phase. First measurement is tweeter only, followed by woofer only and tweeter and woofer combined, with the mic at 1m. Then the woofer near-field measurement is taken.

Part of the hassle factor is moving the PC into the lounge. Here is JustMLS in action.

Two Nines and one Three. Here, the E-IIIs are sporting a new midrange driver that is the subject of another thread.

The E-IXs perched on their stands and looking like they need another coat of Danish Oil.

Finally, the hardwired XO.

James