JonMarsh

Notice pricing has increased for all the designs in this section of the forum. People should use the BOM's and check with suppliers for current prices

This Saturday I got around to testing the SCC300 Sonic Craft woofers, and the TC2+ woofer in the Arvo MkIII test mule. The Sonic Craft woofers did exhibit the sensitivity gains I was looking for over the Titanic MkII's, but had a bit higher mechanical Q than I was expecting. Their response is pretty smooth out to 400 Hz or so, but gets a bit ragged above that. No surprise all in all, but didn't exactly Knock me off my feet.

The TC2+ had a lot to live up to, given expectations about this driver, and for $15 more apiece than the SCC300, it delivered handily.

Total sensitivity was not as high in the mid bass as the SCC300, but low bass held up quite well in the U baffle down to nearly 50 Hz without EQ. Quite pleasing was the lack of glitches in the impedance curve until well above 1 kHz, and the relatively low amplitude of these glitches- this is a very well behaved large cone.



I also did chirped sine testing, and this was interesting- the TC2+ is clearly very articulate and "fast". Very interesting driver.

Here's the test mule with the "full aluminum load"- TC2+ woofers, HiVi midwoofers, and SS9800 Scanspeak tweeter.





And from the back,





I went back and tweaked up the passive crossover design after importing the new measurement data. Didn't take a lot of work to adjust for the new driver impedance and response- no topology changes were involved. Note that NO diffraction control is in place, so there's some roughness in the upper end of the tweeter reponse that should be "gone" in the finished speaker. Love that SS9800 tweeter....

This is without any external EQ, folks.... even I wonder if this isn't too good to be true, but we'll just have to build the crossovers and see what happens. At least at the measuring point, about 4 feet from the front of the speakers, this should be the response. It will be interesting to look at the system power response over a 30 degree arc, and see how that turns out.





Hmmmm, got to start getting the coils and caps together! Now, the question is, do I build the crossover starting from the bottom up, or the top down? Probably better do an inventory on parts and see what I've got- I bought quite a few for the last version, so by unwinding a few inductors, I should be set to go soon.

Regards,

Jon

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Dennis H

Dang! That's impressive unequalized response, Jon!

Ya know, that looks about like a natural B2-40 low end rolloff. That means, for HT, you could use most any prepro with a 40 Hz XO. Most of them have a B2 highpass and an LR4 lowpass so that would give a nice LR4 acoustic XO to the sub.

Dennis H

Jon, did you check the T/S parameters of the TC drivers. The O-Audio site is confusing. It says they are dual voice coil drivers but the published T/S parameters appear to be for a single coil driven with the other open. The following numbers from the PDF file are internally consistent so that implies Q was calculated with one coil.

Re = 4.1
Bl = 14.2
Qe = .57

But that would give a low Q with both coils driven. Todd's simulated response curves for both coils driven are inconsistent with that. He has a 60 liter, Q = .7 box but that's the correct size for a single coil, not both coils. And he has the same sensitivity for either series or parallel wiring. As well, he has Re = 3.8 on the HTML page but that's not internally consistent with the other numbers.

Help. Confused. :?

ThomasW

When Jon and I last spoke, he said when wired in series, the VC's were 5.something ohms. I don't remember if he said 5.6, 5.9 ........ anyway something like that.

I'm pretty sure he didn't measure other T/S parameters. Our fundamental concern was if the stated efficiency was accurate (it is), and where the 1st cone breakup mode was (~1.4kHz)

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JonMarsh

Thanks for the kind words... there is some shaping in the crossover network, obviously, and the way the network design works with the tapered U baffle for the woofer, but no external active EQ. The original Arvo I hoped to get down to 70 Hz flat without EQ; this is better, and as you observe could support a lowish crossover point to a monopole sub. That's exactly what I have in mind... when these are done, next task will be to get my HE-15 out of the closet...

The best thing about this is that it's picked up about another 3 dB of sensitivity; I expet the net sensitivity to be 87 dB for 2.83 VRMS; not exactly a SET friendly load, but considering most of the Seas Excel based systems are on the order of 82-83 dB after baffle step compensation, not shabby.

And no stack of amps and active crossovers, as with Linkwitz's Orion and Phoenix.

We'll see if it all pans out as well as hoped, but then there's the MkII current version with DPL-12's at Thomas's, which works quite well... so I have some confidence.




Based on what I'm seeing, the specs are reasonably consistent and correlate tolerably well with the driver as delivered.

This is one of those things I hate about this business; ultimately you can only go by the delivered hardware, and hope they deliver it consistently!

That impedance plot is for two drivers; the VC's for each driver are wired in series, then the driver's are wired in parallel. It's pretty normal for the midbass impedance minima to be only slightly higher than the DCR. Based on that, I should be seeing 4.1 to 4.4 ohms at the minima, and that's pretty much the case. OK, I confess, I haven't had my CLIO system calibrated to an NIST standard, but it's probably pretty close...

I didn't measure the T/S parameters yet- I'd like to burn them in a bit and then check. It was a near miracle just finding the time to do the work yesterday- after I finish this post, it's back to work emails. Yuck. I feel like a victim of our success at Infineon....

Anyway, I'm encorage by what I'm seeing; in a different baffle design, I'm thinking that a set of four per side will work pretty well with my RD50 ribbons. While our current preference for crossing over the RD's is 4th order L-R at 600 Hz, I suspect than an 8th order elliptic LR equivalent at 400 Hz might be OK, and just the ticket with these 12's. They seem well behaved up to 800 Hz, aside from the beaming.... a 400-600Hz crossover may be reasonable- something I wouldn't ever consider with any other 12 than the Eton.

Thomas's comments are based on the LspCAD prediction of the minimum impedance; which is based on crossover reactance and interaction with driver impedance; because of how the driver model is converted to an electrical model which interacts with the crossover impedance, sometimes it gives numbers that are a little low- but also, there's the interaction with the midbass crossover, and LF crossover.

I'm probably going to look at this a few times over the next days, and make sure there's nothing obvious I'm overlooking before beginning construction.

~Jon

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Dennis H

Hey guys,

I know you are partial to metal domes but I'm wondering how hard it would be to make a Scan 9700 or a Seas Millennium work in the Arvo. Just looking at objective facts and figures, without listening to them, both fabric domes look superior to the 9800. The 9800 has 0.1mm Xmax. The 9700 has 0.4 and the Millennium has 0.5. SL has tested (and used) all of them. He found the 9700 had quite a bit less stored energy than the 9800 and the Mill was better yet but not by all that much. Cost, cheapest to most expensive, Mill, 9700, 9800. Of all those factors, Xmax looks like the biggest deal to me but what do I know?

Just curious, inquiring minds and all that good stuff....

JonMarsh

Well, you know how it is, Dennis, I have my own wacky reasons....

First, let me say that the Excel T25CF-002 is probably the finest soft dome tweeter made; the only other high value part of tested which comes to mind, and which I ruled out because of it's more limited range is the Hiqaphon series.

The SS9800 is flatter in portions of the spectrum which I care about, though, because of the crossover characteristic. Also, part of how I ended up choosing the SS9800, besides it's basic performance, including low distortion due to the SS SD2 motor, is due to the impedance curve and physical properties- it's very easy to drop it into the same hole (literally) as a Vifa XT25, with only minor tweaks if any to the Zobel.

With the crossover I use, equivalent to an 8th order L-R for the first 48 dB or so of attenuation, the specified Xmax hasn't been a problem.

Some of the energy storage issues for the unmodified version of this driver are due to that horrid little diffusor they put on it; the bane of hard dome tweeters and their manufacturer's attemps to make the measured response/dispersion above 15 kHz plot better (numbers over sound). It's very easily removed....

Without the diffusor, there's a shallow roll off above 15 kHz (and I mean shallow), which I suspect is due to the time difference between the center and edge of the tweeter- I've seen the same thing with similar modified MB Quart tweeters.

Last, due to differences in distribution channels, we pay less for the SS9800 than we would for the Excel, particularly at the quantites we buy.


That's an awful lot of rationalization for this early on a Sunday morning!


~Jon

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Al Garay

Is there an update on the Arvo project?

I lost track when Jon was going to Colorado for his Arvo vacation.

Thanks,

Al

ThomasW

Jon's Colo vacation was canceled a couple of weeks ago by his boss..........

At this point the only thing to 'update' with regard to the Arvo design is to fine tune the XO. Given Jon's recently revised work/travel schedule for Jun, July and Aug, we're not sure when time will be available for the XO update will be finalized........

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Al Garay

When you have a chance, can you expand on your impression of the SCC300? I realize it did not measure up to the TC2+ for the dipole Arvo project. But what about as a woofer for a 3-way (crossed at 275Hz) or a sealed subwoofer (crossed below 50Hz)?

I have a pair of SCC300 but would not be hard to replace with a pair of TC2+. I would appreciate the lower extension, smaller cabinet size perhaps even a 60 liter instead of 81 liter box (better WAF)and less likely to clip with some movies and not to mention the greater flexibility. So, I'm talking myself into a change. Just need some guidance from the master(s).

Thanks,

Al

JonMarsh

I haven't had time to do exhaustive testing on the SCC300, because I've been too exhausted myself! However, compared wtih most "subs", it's a better choice if you want to go up to 250Hz or so.

In a sealed box with low crossover, I'd probably pick the DPL12 over the SCC300. OTOH, the SCC300 is more sensitive, but keep in mind it has a lower XMAX also. The DPL12 is one of the lowest distortion drivers below 100 Hz in it's XMAX class. Though designed for dipoles, its a great sealed box driver.

Now, the SCC300 is a little bit of the jack of all trades, master of none school. With any driver, it's the total optimization and tradeoffs, and what do you need for your application? I may end up putting the pair I have into smallish sealed boxes with PE plate amps for the bedroom. Haven't really made up my mind. They would work in the dipole, they would also be fine in an IB; and do have the higher sensitivity I desired (compared with DPL12's or Titanic MkIIs), but for my application the TC2+ was a closer fit. Just right, instead of very close.

Regards,

Jon

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goskers

Hi Thomas and Jon,

I am very intrigued by the arvo as I am a previous orion owner. My orion complaints were lack of overall lowend output and complexity with multichannel amps and cables everywhere.

The arvo looks like it may be right up my alley when all is done. Can someone make a guess on if the output with two mids and two tc sounds woofers will be greater than the orion's?

Will there be a passive option for a high pass that will make adding a sealed sub for the sub frequencies an option or should that be active?

Thanks and waiting in anticipation.

wasser

ThomasW

Al,

The TC2+ was chosen because of it's 'fit' into the Arvo design with it's all passive XO. There's certainly nothing wrong with the SCC.....

Hi Joel,

I received your email, and have replied...........

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JonMarsh

Hello Wasser,

Having greater output capability than the Orion was a consderation in this project- obviously, comparing the XLS 10" 12 mm Xmax woofers and single W22 midwoofer to the dual TC2+ 12" woofers (18 mm Xmax) and dual HiVi M8a woofers shows where I was headed. Another goal was wanting to have a system that could be driven with a sinlge amplifier channel on each side.

Now, the Orion is a great speaker, and I understand full well the arguements behind doing a three way active crossover and implementing all the necessary filters that way. Heck, the first 3 way active speaker I built was in the early 70's, with a homemade DIY rackmount active crossover (12 dB/octave), so it's not like I don't have a little experience there...

But, my preference in this case was also having something of a test bed for listening to relatively high power amplifier designs I mess around with (150 watts/ch and up), and I have two pairs of Aragon Palladiums as well as an 8008 BB X3 and so forth, plus some projects in progress, so amplifier power wasn't an issue.

The idea was to try to juggle and optimize the acoustic aspects of the design so that minimal or readily implmented filtering in the crossover was mostly all that was required, with some small amount of additional LF EQ.

The results with Thomas's first system using the DPL12's was quite encouraging, but to optimize for passive, we needed a bit different woofer parameters, hence the search for a slightly different woofer with a bit higher sensitivity, and readily parallelable (i.e., roughly 6-8 ohms). The TC2+ seems to fit that bill very well.


Do keep in mind that the first limit on output is the woofer and mid bass excursion; even quadrupling the acoutic power capability results only in a 6 dB output level improvement.

The goal was to produce a speaker that can be comfortable with 90 dB+ average and peaks to 110. I think this will be the case in the finished Arvo, and considering the real "footprint" isn't that much bigger than a pair of the bookshelf M8's on stands, I'm pretty excited.

For more output, there's my next project, which invovles the RD50 BG ribbon at it's core, from 600Hz or so to 5-6 kHz; and possibly four TC2+ in an array on each side from 600 Hz down, and some kind of ribbon tweeter array in the final version. Crossed over to a monopole sub below 50 Hz or so; Stryke HE15.

It's annoying having all these parts sitting around and so little time to work with them lately! I've had the RD50's for two years...

Anyway, I did order about $500 worth of crossover components today from Parts Express, to finish up what this first set should need (did I mention a high power passive crossover at 200 Hz and 1.25 kHz isn't inexpensive?), so with luck the crossovers will start coming together within a week or two. Tons of hardware work to do for my day job, though, and overseas travel the second half of July. I can't believe June is over half over already, either!

Realistically, I'm expecting to have these updated version running before the end of the summer. I wish it were sooner, but if you saw what I'm doing in my day job right now, I think you'd understand.

BTW, there's no reason this set couldn't be used with an active crossover to a monopole sub, anywhere from 60 or 75 Hz and down. I'd recommend staying as low as possible in the crossover point to keep the benefits of dipole midbass.



~Jon

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goskers

Hi Jon,

I know this is not complying to the thread but I am interested in your use of the rd50 as well. How would you do the xo in the rd50, tc2+ and may be fountek* full ranger? Active - passive?
This would seem as it is a no-brainer for cost no object, last speaker I would ever build type project.

Thanks

ThomasW

At this time it's almost pure speculation, but I imagine there would be a mix of XO's depending on how the system shapes up.

We'll probably buy one Hi-Vi M-12 to do a shootout between it and the TC2+ .

Pretty much any system can be built all passive, but sometimes it's not the best performance choice. Also there are times when going all passive is virtually as expensive as going active.

The Fountek ribbons are one lower cost option, their performance probably isn't on par with some of the higher end ribbons like those from Aurum Cantus or the newly upgraded Ravens.

Given the current backlog of projects, it's likely going to be years before any significant amount of effort is directed toward this project.

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Hank

That's a surprising lesson I've learned on this forum from the Poohbahs.


Oh-No! That's the project I got the Poohbahs interested in a year (2 years) ago.

goskers

For now I will go ahead and build the arvo part. I hope that someday the time is made available for the rd50 project to take shape. An end all system would be great!!

Thanks for all the hard work guys.

JonMarsh

I don't know whether Thomas is being overly realistic, or a little pessemistic!

Hmmmm, let's see. Projects.


1. Arvo Part - in progress, obviously!

2. Aragon Xmod- started PCB layout, after completing 4th spin on electrical design. Completion for 1st boards uncertain- Autumn, perhaps? Most parts on hand.

3. Line Array- untitled - how about, "That RD50 Thingie"?
The only thing that stays the same is the midrange-


I'm thinking about doing a "mule" after I finish these Arvo's, setup just for evaluating 4-12" and the RD50, not worrying about a tweeter line for the time being, but just evaulting getting 75Hz to 15 kHz done as well as possible, without a super tweeter. Expected crossover point is ~500 Hz. I could proto this with an active crossover by modifying my X1 active crossover. It has some shelving EQ capabilities, in the LF which would work just right.

While I'll never say never, (regarding an active crossover for this project), the intent all along was to go mostly passive, with perhaps a simple analog EQ box (one of my balanced Diff gain cells), and use an active crossover just to go to a monople sub below 60 Hz somewhere. I've got a Sumo Delilah II I've been reserving for those duties...

The question is, should I build the RD50 mule sooner, rather than later, and temporarily mount my four TC2+ in it for evaluation before finishing the cosmetic versions of the AP2? Probably would be a good idea... plus it would be a fun, if cruel, tease to Hank...

Of course, it might also just distract me more than a little!

~Jon

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David Meek

What ever happened to the Eidolon clones?

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ThomasW

We should probably publish a schedule. But that might get us into even more trouble..........

Right now the priorities are the Arvo, and the Aragon X-mod project.

The RD-50/75 hybrid line array was shelved because we didn't have a good woofer option, and everyone was coming out with new ribbon tweeters. Now we have a solid woofer and tweeter options, but the money has been redirected to the projects listed above.

So yes eventually we'll do the line array, but it certainly won't be this year....

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goskers

OK, i give. I am definitely sold on the Arvo so I am itching to have that be first on your plate.

Can you tell me a little more about the new pcb's for the Aragon stuff? Will this be for sale? What exactly does it replace in the internals? How does this stack up with other stuff in regards to sonics and overall presentation?

Again, thanks to all for my new found favorite hideout.

wasser

ThomasW

The X-Mod is Jons project for updating the 800x series of classic black Aragon amps.

The goal is to have a powerful amp that has a sonic signature similar to Ayre, Theda or other high-end nonglobal feedback designs.

The plan is to reuse the chassis, heatsinks, transformers and a few selected components from the original PCB's.

The complexity and expense and scope of the project has grown considerably over the last 8 mos. The component cost and construction time will probably make it unrealistic for us to bring it to the retail market. We've talked about trying to make a DIY version, but we're using some fairly rare and not readily available components.

As the project moves from the planning and procurement phase to the actual building stage we'll create a thread about it.

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JonMarsh

Ooops - my bad. They should have been on the list. Actually, David, they're more like a cross between an upgraded Eclipse and Arcus, than an Eidelon, as they're two ways, while the Eidelon is a three way. Upgraded, in the sense of lower IM in the bass and upper mids/lower highs. And a bit more bass extension, too. Finding a week off to do the veneering and build the crossover enclosures is the main "hold up"- the crossover design is pretty much done (it's "just" a glorified M8, ya know, take to it's illogical extreme). You know, if some's good, more's better, and too much is just enough.




That's not really supposed to be a "public" project yet- it's been worked on and off for a couple of years- primarily because Thomas and I have quite a few Aragon's between us... some would say an embarassing number of Aragon's! You know, some folks are Bryston freaks, well, we had an Aragon period back when I was building the X1 clones, which actually continued for sometime there after. Even though they're not "state of the art" sonically, they're a pretty well balanced all around design, and as "conventional" amps go, you have to pony up to something like Krell or big ML's to get something better.

But we're also fans of Ayre products (company who's principle designer is the original founder of Avalon), an old friend of mine, and the non loop feedback thing really does work pretty nicely. We've got 2 Ayre V5's, currently both at ThomasW's, and even before getting the V5, I was playing around with some non loop feedback circuits; they have a certain naturalness which is hard to find in solid state gear; more prevalent in very good tube equipment.

Anyway, the Xmod is a combination of a complete new channel PCB, (basically completely rebuilding each channel; only original component used is the heatsink and speaker relay), and a new power supply board will also be incorporated. It's gone through two major evolutions; the current circuit is what I'm planning to have a number of PCB's built up, so we can retrofit amps. The basic design sort of evolved and "got away from itself"; it's designed to be inherently balanced input, using FETs in parallel for low noise and high class A bias current and linearity in the front end stage. The complementary differential stage is cascoded, then coupled into a complementary VAS stage by both common emitter and folded cascode connections. This uses both sides of the differential current to drive the VAS stage, and keeps linearity high. The front end is true class A in that the signal swing required to clip the amp is less than 1/4 of the idle bias current, even considering the heavy local degeneration and low gain. To allow operation of the amplifier as a DC amp and not worry about preamp offsets, I've added an option for a revised front end gain and using a Jensen bridging transformer on the input. Bandwidth with the transformer is reduced a bit on the top end (-3 dB at 130 kHz open loop, compared with 225 kHz), but the bottom end holds up well, being down -3 dB at 0.2 Hz. Yeah, I said two tenths of a Hertz. No need to worry about LF group delay.

The output stage is a variant on an emitter follower triple, designed for very high open loop linearity (typically 0.004%) and optimized for driving capacitive loads without an output decouping inductor. It uses 230 watt On Semi extended beta transistors (MJL4381 and MJL4302) instead of the 150 watt Toshiba devices. All modded amps will have the full complement of outputs usually used in a Palladium or 8008 BB, not the reduced count used in 8008ST or 8002.

The power supply board replaces all the supply caps (roughly doubling storage capacitance, and adding PP film bypass), fast rectifiers, and a new grounding scheme, plus a DC input filter to keep the toroidal power transformers quiet and working in the most linear flux region even when called to deliver high power levels. One of the weaknesses of most toroidal transformers is their susceptibility to flux imbalnce if there's small amounts of DC on the neutral to hot connection (I mean small, like a hundred or two hundred millivolts). The low impedance of the windings, and small core which gives toroidal transformers low voltage drop and relatively light weight can result in significant DC bias current with a small offset voltage, and cause the transformer to start to saturate prematurely under heavy load. Big EI core tranformers are much less susceptible, because the winding resistance is usually higher, and the core size larger for a given primary magnetizing inductance.

Because of the number of parts involved and the local regulation and stuff, I don't know that I'd call this a DIY project- if there was interest or demand, I could probably sell PCBs. The parts aren't hard to get; between Digikey, MCM, and Newark you could source just about everything or close equivalents. I'm ambivalent about doing that, though, because I don't want to publish schematics; there's some things I learned on some consulting projects which are in this design, and that has to be restricted. But I don't really want to start up a cottage industry building new Aragon modules, though I have a tech friend who would like the assembly work. Basically, it's up in the air, which is why we're aren't talking about this much.

Oooops.

We'll just have to see. Maybe we won't even like how the finished ones sound... but the brassboard is promising, and measures well for an "open loop" type design.

~Jon

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Hank

Yes it would, but us DIY-ers have a touch o' masochism, don't we?
Financially, I can't invest in RD's, woofs and tweets this year (due to two IV's running from my wallet to two college students), so I'm not pushing the Poohbah's. You should probably finish what's on your plate and save the RD50 Thingies for next year, and hopefully Jon will either manage his job hours down or find a job requiring fewer hours.



Yes it would - the daily questions would drive you nuts. This is supposed to be a fun hobby, right?

JonMarsh

Yes indeedy it is!

Today it was a fun day- there was $500 worth of crossover parts waiting for me in a relatively small but heavy box... oh goody!

Jantzen and Solen inductors, Dayton polypropylene caps, mills resistors, and AudioCap Theta caps. The AudioCaps are pretty cool- 10uF film and foil are much heavier and denser than their more reasonably priced metalized brethern. The 10uF AudioCaps, though physically much smaller, weigh MORE than the 100uF Daytons. The Daytons are going to be used in the woofer crossover; the AudioCap Theta caps will be going into the tweeter crossover, of course. True film and foil caps are a little pricey, but I think they're justifiable in the tweeter circuit, and sometimes in midrange low pass.

I'm going to do some physical measurements on these caps, too, just to satisfy my curiousity. Though I don't really think ESR and ESL tells much of the story regarding sound.

Regards,

Jon

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JonMarsh

OK guys, this is in response to requests for prelimin detailed info on current baffle design, crossover, and LSPCAD modeled behavior.

This is NOT the finished design- this is an evolutionary step, what I'm calling Release Candidate 1 on the V2 design. This is a newer/different design than ThomasW is listening to, and pretty pleased with, but that doesn't mean it's better, it's just NEWER; new baffle design, new crossover, etc.

This is not intended for you to go out and make saw dust and solder with, but it's a reference point in the development, and should allow you to estimate the cost and effort involved, as well as the kind of results we're shooting for. OK? Right click and save to disk.

3/17/05 Note the links below are broken and can't be fixed, since the hosting server no longer exists. See the end of this thread or the other Avro thread for the latest data.


Front Dimensioned Drawing PDF


Side Dimensioned Drawing (PDF)


Prelim Crossover Schematic PDF


LSPCAD Plot Diagrams


The cabinet diagrams don't detail the Oak side panels or other trim features I'm considering. It also doesn't detail the rear relief bevel I'm using for the drivers- like this...





Have a good weekend, folks.

~Jon

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Dennis H

Bravo, Jon. Take that, all you alligators!

A couple of questions.....

Is the tweeter wired with reverse polarity?

The mids have a separate Zobel circuit. Does that just patch in somewhere in parallel with the leads going to the pair of drivers or does each driver get its own Zobel?

You show the 2 woofers in series but that's a series/parallel arrangement of the 4 voice coils, right?

ThomasW

Dennis,

Yes the tweeter is electrically out of phase. We reverse the polarity of the tweeter output leads at the zobel input/output connector. That way the tweeter itself is then wired in phase. This may seem confusing and of course it is ...

The M8a are single VC drivers.

As far as I know there are no zobels for the midwoofers

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IB subwoofer FAQ page

ThomasW: curmudgeon in training, putting the no in innovation

JonMarsh

The net electrical phase of the tweeter is out of phase, becuase the crossover, in the transistion region, is mimicing an 8th order L-R, which requries out of phase connection, as does the 2nd order L-R.

The "free floating" zobel is just connected to the input. It's optional, but it reduces the otherwise drastic impedance swings which would occur going from an 4 ohm tweeter to a series connected 16 ohm midwoofer load. With it, the impedance curve is pretty consistent from 100 Hz to 20 kHz. Not that I think there will be very many SET amps used with these... (see the cruel impedance modelled at LF- not sure if that will be "real"- I expected something closer to 3 ohms with dual 6 ohm drivers). But non feedback solid state amps also have a somewhat higher output impedance than conventional high feedback designs, and this will minimize any tonal/voicing errors wtih different amplifiers. I hope...

~Jon

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the AudioWorx
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Modula MT
M8ta
Modula Neo D CC
Ardent
Modula MT XE
Modula Xtreme


still coming in 2010....

Ardent Cxi (updated design, new woofers)
Ardent CCX (Compact Center Xtreme)

JonMarsh

Well, I finally spent a little time on a weekend on something other than (no, I'm not even going to say it, out of deference to Hank and others in similar pain... )

ANYWAY, crossovers built, crossovers wired up to the test mule, test mule setup. I've never had a speaker sound this good before any tweaking or adjustment of crossover, but then I've got a pretty serious stack of drivers here; not much surprising there!

Only one speaker running. Stere image is a little narrow....

Great definition, very transparent.

I also hooked it up with one of my M8 MkIV and did some video- marked improvement in soundstage widt and depth over two M8 MkIV; I think that's because the dipole is over on the right, and I'm sitting to the left of the CRT projector, and the dipole has more uniform off axis power response. Just a guess....




Listening to "Women of the World Celtic" collection from Putumayo World Music; Maire Brennan, Fiona Joyce, Karen Matheson, Mary Black, etc. Really sweet.... I think I'm gonna like these speakers....



~Jon






LF Crossover

(Don'tcha just love those AWG 12 inductors? )



MidWoofer Crossover




Tweeter Crossover

The LPAD will be removed and fixed resistors (Mills) installed when value is finalized. Yeah, those are AudioCaps Theta Film and Foil in the Tweeter crossover. Expensive, but they sure sound good.

Female voice sounds REAAALLLLLYYY good on these speakers....

Attached Thumbnails

       

__________________
the AudioWorx
_______________________________

Modula MT
M8ta
Modula Neo D CC
Ardent
Modula MT XE
Modula Xtreme


still coming in 2010....

Ardent Cxi (updated design, new woofers)
Ardent CCX (Compact Center Xtreme)

JonMarsh

Today I got most of the materials for building the 2nd V2.5 test Arvo, though it will be with a different front panel construction, partly because of problems getting the materials I used for the last two, and to try out something I may use for the RD40 based ribbon system.

Also, the 24 ft Kimber 4TC for wiring the drivers and crossovers together came in. This is a low inductance braid, teflon insulated, with net AWG of 13 per conductor. It will be used for all the driver interconnect wiring.

After considering some ideas for a home constructed "wood look" box for the crossovers, I'm now leaning towards a black anaodize rack chasis for the crossovers for each speaker, sort of like a monoblock amp.

Gotta go get some more glue now, it's a smoking 95+ in Livermore, so I've setup to do gluing in my kitchen!

~Jon

__________________
the AudioWorx
_______________________________

Modula MT
M8ta
Modula Neo D CC
Ardent
Modula MT XE
Modula Xtreme


still coming in 2010....

Ardent Cxi (updated design, new woofers)
Ardent CCX (Compact Center Xtreme)

Dennis H

Hey Jon,

For the "wood look," it's hard to beat edge-glued solid wood panels. IMHO they would work fine for baffles (maybe 2 layers) as well as for the extra pieces. You can glue them up yourself but, unless you have a surface planer and a surface sander, or a whole lot of time to spend with a belt sander, it's pretty inexpensive to buy them. Here's one source.

Solid wood panels

Hank

My humble suggestion would be a "wood" box at the back of the speaker, at the bottom, "resting" on the base. The base would be extended 4-5" to the rear of the bottom of the cabinet, so that the crossover box is vertical, almost as wide as the cabinet, and maybe 3" thick.