Modula Xtreme follow up

[1Michael]

There are a lot of people giving the minidsp a try.

[AdelaaR]

I use the DAC in my edirol UA-700 ... and I like it very much.
Bought the thing second hand for $170 5 years or so ago ... it does phantom power condenser mics pretty well and has an input for my guitar too
The DAC is of course one of the most important things in the system after speakers, so if you want to pay $4000 for one and feel that you gain $3600 worth of fidelity over the $400 version ... sure.

[Face]

There are also plenty of people who will tell you that you're crazy spending $400 on a DAC instead of using the one in a receiver or $150 BDP, etc... To each their own.

[Cort]

I am thinking of combining this
minidsp http://www.minidsp.com/onlinestore/d...ts/minidsp-kit
with this sure 4 channel amp

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=320-302

Seems like a couple hundred usable watts per 4-way speaker and crossover for under $200 per speaker, Sounds sweet.

[Silver1omo]

I am thinking of combining this
minidsp http://www.minidsp.com/onlinestore/d...ts/minidsp-kit
with this sure 4 channel amp

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=320-302

Seems like a couple hundred usable watts per 4-way speaker and crossover for under $200 per speaker, Sounds sweet.

Cort,

Just as a note on the Sure amp, the manual says that you should not use a pre amp.

The 2 channels amp has DIP switches to adjust the gain and is supposed to be usable with a pre amp. Manual of 2 channel amp

[Hdale85]

I have one of those boards, I don't know that I'd consider it real high quality though as far as the sound. It's certainly good for the money, but I think the Modula Xtreme would benefit greatly from better equipment.

[Cort]

I agree that the sure is not up to par with the modula, however this might be getting a little closer from 41Hz audio there are also some upgrades as well on the DIY audio board.
http://shop.41hz.com/shop/item.asp?catid=44&itemid=796.
It just seems it would be fun to kick back on the couch with the laptop hooked to a cal'ed mic and dsp and dial in a speaker for the room.

[JonMarsh]

Well, you can get an idea yourself by taking the crossover schematic and working up your own BOM. There's a reason we call this DIY.






Ignore R12 and C12- not used.

Detail values will change for the SO, but the topology and configuration will not be very different- this can give a fair cost estimate. The SO may be even less, as it may not take as much shaping on the midrange- but that's just informed speculation, so to speak.

Had a request for updated crossover values assuming woofers about 2 dB less sensitive than the Scanspeaks I used originally - worked this out this afternoon. Posted in case this is of use or reference for anyone else.


On the midrange, change R1 to 5.1 Ohms, change R4 to 20 ohms.

On the tweeter, it's a bit different situation because of the waveguide and the way we handle compensating it's frequency response and level- Change R5 to 4.0 Ohms, and change C6 to 3.9 uF. If you don't change C6, there will be a presence range emphasis- will be too hot there, even though the rest of the level is OK. R5 and C6 interact with the driver characteristic to determine level and frequency response- it's a minimum component solution from a design viewpoint, but requires changing both to change level.

[claudius]

Hi Jon,
Having built the Modula Xtreme (not veneered yet), I have a few annoying questions for you,( please be patient).
In the baas crossover i'm using the Mundorf T130 transformer core inductors , what do you recomend forL9 and L10.
Moving on to C173n-T6-90 the L8 is presumably a correction inductor so as long as ri=1.200ohm the wire gauge is not important Ahh.. but what aboutL2 and L4 and while i have you're atention C4 is 300uf what type of caps should i use.
Finally and you're not going to like this ...but would it be too hard to sustitude the mighty Be6640 or even the not so mighty Accuton C30 in place of D 2608.

[capww8]

Jon,

There was a lot of talk in the Ardent thread about launching a website documenting your projects. Has this ever come to fruition? I've been scouring your threads but have not located a link.

Thanks!
Adam

[JonMarsh]

Jon,

There was a lot of talk in the Ardent thread about launching a website documenting your projects. Has this ever come to fruition? I've been scouring your threads but have not located a link.

Thanks!
Adam

Sadly, not yet. This has been the summer of my discontent, as it's been mostly 7 days a week at work, due to the inability of one team to hire a replacement engineer since the end of February because of one that quit (due to having personal style issues with the Mktg Manager, who tends to micromanage unless you go toe to toe with him). Which I do. But the work is still there- as last weekend again, and up again at 2 AM to get something out by 2 PM yesterday afternoon, followed with a conference call with Asia at 7 PM. Ugly.

However, I'm promised by my real manager to be off this hook by the end of September. I'm also doubting that he can deliver, as this other product group hasn't had a person for me to interview for them since April.

We'll see....

[JonMarsh]

Hi Jon,
Having built the Modula Xtreme (not veneered yet), I have a few annoying questions for you,( please be patient).
In the baas crossover i'm using the Mundorf T130 transformer core inductors , what do you recomend forL9 and L10.
Moving on to C173n-T6-90 the L8 is presumably a correction inductor so as long as ri=1.200ohm the wire gauge is not important Ahh.. but what aboutL2 and L4 and while i have you're atention C4 is 300uf what type of caps should i use.
Finally and you're not going to like this ...but would it be too hard to sustitude the mighty Be6640 or even the not so mighty Accuton C30 in place of D 2608.

First, re inductors:

L9 can be a high DCR inductor with small gauge wire- just change the resistance of R11 so that the combination adds up to 3 ohms. It's a shunt shaping network.

L10, OTOH, is a series inductor and should be low DCR- recommend AWG 12 or 14. L1 in the original design was a Jantzen C Core inductor- individual checked and tuned for inductance with an LCR meter. I've since "think" I've identified some hysteresis losses and inductance modulation, and having replaced a similar inductor in the Ardents with an AWG 12 air core, prefer the sound- more focus and better integration of fundamental and overtones in bass instruments like stand up bass- haven't had an opportunity to try that with these yet.

L2 was an AWG 14 part; note the R internal rating of 0.4 ohms. Some purists think foil inductors will work better on midrange series, due to lack of skin effect, but my calculations show this isn't a factor for solid wire at AWG14 up to about 30 kHz. AWG 15 Jantzen was used there. L4 is also a low impedance zobel, so AWG18 or 20 is OK, just adjust the size of R2 to get the total R = 8 Ohms. C4 I use film caps- either Dayton metalized polypropylene or Jantzen Cross Cap or Solen Fast cap. The cheap solution would be bipolar electrolytics, but the dissipation factor and stability is a question mark in my mind.

Something else to keep in mind that I didn't pay enough attention to, is the volume which the resulting crossovers take up- my conclusion was that the 3rd cabinet was needed to house the LF crossovers, freeing up space for the woofer volume, AND to raise the whole system up off the floor, which improved the launch, frequency response, and imaging.

Last question- tweeters- do you have in mind ditching the waveguide? If so, then those hard domes are feasible to develop for. With the waveguide, I don't personally think so, though I haven't tested exhaustively that way. My experience so far is only a few tweeters couple well without resonance problems to the waveguide, and I've yet to pull it off with a hard dome of any kind. Also, the Accuton and SS Be tweeter have plate designs which would make it very problematic. OTOH, using them as a more conventionally mounted tweeter should be feasible- my tentative plan now is to rebuild this system into a new dedicated cabinet, probably more akin to an Avalon Isis than anything else, and use the SS 6640 as a direct radiator tweeter for the top end. I have both that tweeter and the Accuton C30 on hand, so later in the fall it wouldn't be hard to prototype a new network- problem right now is free time- or lack of it.

I am going to be testing the Ciare MT32 with the Jantzen waveguides, but probably not for this system; I have in mind a souped up NatlieP with Illuminator woofers and the waveguide plus tweeters.

Real progress won't happen until my work issues get resolved; I hope to be free of supporting this other team by the end of September. There's a lot of things even on the back burner for my real/main job at work, to say nothing of my personal life...

L10

[claudius]

Thank you for the detailed response.
As you've stated the low frequency network with total of almost 900Uf film caps per box takes some room but it's worth the pain and resulting sound is superb.In my own case, I went from constructing boxes for what was to be Tony Gee's Galactica at well over five feet to Isies at just under five and eventually somthing much smaller and let me tell you folks if you've never had to progressively chop down you're lovingly made speaker boxes while maintaining some dimentional accuracy, you haven't lived and that mean's avalable room for the crossovers shall be at a premium.I'll just have to work somthing out.
correct, replacing tweeters would mean ditching the waveguide as well as changing the head unit completly.
Finally Jon, having been through somthing similar to you're work situation a few years back,I empathies with you, all i can say is to keep you're chin up and may the force be with you and rest assured that you're loyale disciples here at HT shall patiently await you're triumphant return to all things audio.

Regards

Bill

[JonMarsh]

Thanks for the thoughts, Bill.

I'm just finishing packing up for a week on the East Coast; was in the lab yesterday most of the day. Big meetings with my management and guys in our division at HQ in Europe; I'm doing a couple of key presentations on direction and technology; should be interesting to see how the rest plays out. I may also get to do more interesting things at work the next six to nine months. But I've got to get this other division to hire the warm body they'v had a req for (that I've been filling in for), since February, and so far have made no progress. In fact, no candidates to interview in the last two months!

The last guy I interviewed on the East Coast for our division in late June, has accepted our last offer, and should start the end of September; he's pretty promising, though young, he's got an MSEE and PhD. This doesn't directly help me, though eventually it should mean I'm not going out to the East Coast as often.

~Jon

I feel for you with the cabinet situation- I'm already sketching new cabinets for this driver complement on the midrange and woofer but with probably the 6040 direct radiator on top to see what I can come up with. I expect the economy to be slowing (well, it can't really slow any more, it will go in reverse, I suppose!) next year, and hope to have more free time. We'll see how that works out!