Input Needed: Peerless 830875 & Vifa XT25TG30-04

[jimofoakcreek]

First some background about me:
I’ve already built two speaker systems with routed recesses and DIY crossovers. Now I want to build an upgrade to my existing upstairs system. My goal is better bass response than what I have now. Music comes first; HT is secondary. My upstairs amp is an Panasonic XR50 digital HT Amp, 100 watts x 2.

My existing upstairs speaker was designed by Jay Kim. It’s a ported 0.5 cu ft box with Dayton RS180 woofer and Seas 27TDFC tweeter. The x-over is a pretty good design. But I would like a little more bass.

I want to build a new MTM speaker system using Peerless 830875 6-1/2" Nomex Cone HDS Woofer and Vifa XT25TG30-04 1" Dual Ring Radiator Tweeter. My cabinet choice is a Dayton 1 cu ft box that is now on sale.

My wife won’t tolerate a bigger box in the living center than 1 cu ft. A sub woofer is not an option. My cross over choice is a generic Dayton Audio XO2W-2.5K 2-Way Crossover 2,500 Hz. I could upgrade the x-over later. This would be a ported design.

Pricing this Peerless/Vifa system out with everything is around $600.

The Dayton RS722 kit is on sale for about $100 less. Is my proposed system a worthwhile/cost effective upgrade?

What do you think? Any thoughts and input would be greatly appreciated!

[ridikas]

I do understand in what you are trying to accomplish. But the proposed speakers will be a complete nonsense unfortunately. Both drivers are pretty incredible, but hard to work with. The Vifa XT25 is one of the best tweeters at any price. I've worked with both drivers extensively.

The 830875 woofers need a lot more volume than 14 liters. They need at least 19-20 liters per woofer to hit an F3 of under 50Hz. In a 14 liter enclosure, your F3 will be at best 60Hz. I can post true T/S parameters for you, but they are similar to the ones at Tymphany. Also, I would ignore most crossovers that we're modeled, they all have ridiculous amount of baffle step compensation. Initial inductor of 1.5mH should give you a full baffle step in-room. One crossover that works extremely well is 1.5mH, 12uF, 0.27mH, and a Zobel of 20uF and 8 ohm. This will give you a crossover point at around 1900Hz. If you use a premade crossover, then this project will be an instantaneous fail. My recommendation would be to build a TM monitor in a 0.75ft3 PE enclosure. Using dual ports, 2"X8" would be a good start.

The Vifa XT25 needs an LCR network. You can steal it from zaphaudio.com (1mH, 4.7 ohms, 100uF), or from Wolf who has used it in his Scandivifas project on this forum. I don't have a crossover I can recommend, but I can model something for you. This tweeter likes to be crossed over between 2000Hz-2500Hz, with an LR4 slope.

[bmaupin]

Are you picking the XT25 because you have listened to it and like it? I think it is a nice tweeter, but not for an MTM since I think that you'd like to cross below 2k, around 1.6k or lower if possible. I'd recommend the RS28A or F.

The 830875 in 14L: Unibox says F3 of 49Hz tuned to 50Hz.

Are you after an MTM because you need more SPL? An MT in 21L will get in the low 40's, 24L will provide a F3 around 38Hz. Use the 1cuft cabinet and reduce the volume as necessary. The XT25 would be better suited for an MT.

[jimofoakcreek]

Thanks to both you guys for your valuable input thus far.

I'm willing to modify my initial proposed project based on your recommendations.

What about an MT arangement with the same drivers in a 1 cu ft box? How would that compare with the Dayton RS722 kit?

Again, my goal is the deepest bass response possible in a 1 cu ft box (or smaller).

[ridikas]

If you're getting an F3 of under 50Hz in a 14 liter enclosure, then the TS parameters you are using are wrong.

[Wolf]

The Vifa XT25 needs an LCR network. You can steal it from zaphaudio.com (1mH, 4.7 ohms, 100uF), or from Wolf who has used it in his Scandivifias project on this forum. I don't have a crossover I can recommend, but I can model something for you. This tweeter likes to be crossed over between 2000Hz-2500Hz, with an LR4 slope.

I personally think 2.2kHz+ for the XT25TG30. It has also been used cauer-elliptically by Jon Marsh at 1.5kHz, apparently without issues.

I measured my XT25 with a WT2 to get the flattest impedance with the LCR, and came up with a 20AWG 1.0mH coil (0.7 ohm DCR), 3.3 ohm resistor, and a 150-160uF cap value range. +/-0.5 ohms variance through resonance and all the way up to 20kHz. I also used an AR SXO with it, voiced by ear, and second order at 2.3kHz. One of my best!

Latetr,
Wolf

[Mark65]

If you're getting an F3 of under 50Hz in a 14 liter enclosure, then the TS parameters you are using are wrong.

No, yours are. In WB&CD, 14L tuned to 48 Hz gets you an F3 ~47 Hz. Dead flat to rolloff, no EBS required. Using the T/S straight off the Tymphany spec sheet. 3" x 14.5" port.

Thing is, the RS180 will do pretty much the same thing, in a bit larger of a box. You can certainly get below 50 Hz with that Peerless, but the main advantage will be lack of metal cone breakup, not "more bass".

Could be a really nice speaker, though, and certainly NOT "nonsense".:rolleyes:


Mark

[donradick]

OP - once again, the advice is to build an existing design. The RS722 looks nice, but reading comments I would strongly agree with one: "the 2 RS180 woofers need a bigger box". I tried 2 of them in a 1 cube ported box, and was not really happy. I am now running 2 of them in a 2 cube tower (mini-statements), and they produce "gobs" of bass. I would suggest you replicate your existing upstairs speakers in a 1 cube box each for downstairs use. I haven't heard a jkim design, but have read several compliments.

You will be in danger of wasting your money on the road you're on. For a single guy, no big deal, but spouses tend to get upset if your $$$ investment does not sound great.

[ridikas]

Jimofoakcreek - Tymphany's T/S parameters can be found here: http://tymphany.com/files/HDS-P830875%20Rev1_0.pdf

They are fairly accurate and I would strongly recommend against using any other older Peerless' datasheets, as they are completely wrong.

Please also find a picture attached of the current batch of Peerless 830875 mid-woofers as measured by WT3. These T/S parameters were posted by Ron_E in this thread: http://techtalk.parts-express.com/showthread.php?t=229811

These T/S parameters are 100% accurate.

Using Unibox to do all of the modeling to get a completely flat response: http://audio.claub.net/software/kougaard/ubmodel.html

Rs = 0.5 ohms.

Using Tymphany's T/S data (less accurate):

14.2 liters (0.50ft.3)
Walls covered: F3=52Hz, Fb=49Hz.
Heavy Fill: F3=57Hz, Fb=54Hz.

12.2 liters (more accurate as it takes into account bracing, driver/crossover/port displacement, etc.)
Walls covered: F3=59Hz, Fb=46Hz.
Heavy fill: F3=60Hz, Fb=56Hz.

Using the more accurate Ron_E's WT3 measurements:

14.2 liters (0.50ft.3)
Walls covered: F3=58Hz, Fb=45Hz.
Heavy fill: F3=60Hz, Fb=54Hz.

12.2 liters
Walls covered: F3=64Hz, Fb=42Hz.
Heavy fill: F3=63Hz, Fb=57Hz.

21.2 liters (0.75ft.3)
Walls covered: F3=46Hz, Fb=44Hz.
Heavy fill: F3=52Hz, Fb=48Hz.

As you can see, 0.75ft.3 enclosure is the way to go. I'm not sure where Mark65 is getting his data from, but it is definitely wrong.

[Whitneyville1]

I too will soon to be playing with the 830875's in about 18-20 Liters ported and using the RS28F-4 tweeter, but NOT an "off-the shelf" cross-over, as you are certain to be disappointed with it. The Vifa tweeter can be made to work, just crossed at a higher frequency. I haven't simmed the 83875 in a cu. ft. sealed or ported to see what it will do. You may be at the point of trading SPL for a tiny bit of bass extension. I stopped at .777 cu. ft. (22 liters I believe) as my gains were becoming minimal. I'm a rank amateur at this, so take this with a large amount of salt, but I think your RS180's would give better bass in a somewhat larger enclosure based on other designs using them I've seen here.
Wolf, Paul Carmody, and many others can guide you far better than I can on both speaker designs, and I urge you to "pick their brains". Just a change of the L1 inductor in your current speakers could give you the bass you're looking for. Best of luck to you, and I'm certain you'll find help if you ask for it.

[jimofoakcreek]

Jimofoakcreek -

Using Unibox to do all of the modeling to get a completely flat response: http://audio.claub.net/software/kougaard/ubmodel.html

Rs.

Thanks for the link to Unibox. Now I am going to do my own modeling with different drivers to design the best possible fit to my requirements.

I may have chosen the wrong drivers. So I am going to do some modeling with Unibox.

THANK YOU!!!!

I'll be back with more questions about more drivers. :D

[arlis_1957@yahoo.com]

consider this.
http://techtalk.parts-express.com/showthread.php?t=223870

[LouC]

Make sure you are talking about T/S for the right woofer. The 830875 is a stock Peerless woofer and quite a bit different beast than the 831735 that was a $30 OEM buyout here at PE. I've used both, but seen them confused in other threads.

The 830 will do about 51 Hz vented in 14 liters. The 831 will do about 50 Hz sealed in the same box, probably low 40's vented. The current specs from Tymphany on the 830 are slightly different than those I used for my build, but the boxes are effectively the same.

The 830875 in the Veepers (http://www.lonesaguaro.com/speakers/VP/Veeper.html).

The 831735 in the PeeDei (http://www.lonesaguaro.com/speakers/Peer28/PeeDei.html).

[Mark65]

I've worked with both drivers extensively.


I don't have a crossover I can recommend, but I can model something for you.



Interesting.:rolleyes:


Ron E got his vas from added mass with the WT3. I don't trust that measurement. No slight on Ron, I just don't trust the WT3 for that, it's way too finicky.

So: Using Ron's TS (with the exception of vas, which I used from the Tymphany sheet you linked to above) I got F3 of 46.7, F6 of 41.04, F10 of 36.07. 14.2L net tuned to 47 Hz. 2.5" x 10" port.



Still not better bass than the RS, but under 50Hz. Dead flat to rolloff.:)


Mark


PS: Why on earth would you heavy fill a vented cabinet?:confused:

[bmaupin]

PS: Why on earth would you heavy fill a vented cabinet?:confused:

From my experience, it would be to kill the low end.

[Wolf]

Mark
PS: Why on earth would you heavy fill a vented cabinet?:confused:

IME;
-You can tame a rising bass response or bump if you can't physically tune lower.
-You can limit excursion a bit by impeding the flow in the vented box.
-You can reduce port-mach with stuffing.
-You can use a higher Qts woofer in a vented box.

I always use a good handful in a vented box anyway, even if it's not stuffed heavily.

Later,
Wolf

[Mark65]

A good handful, sure, but that's far from heavily stuffing a box. I use a good handful, too, but heavy stuffing is for sealed cabs, IMHO.


Mark

[Wolf]

A good handful, sure, but that's far from heavily stuffing a box. I use a good handful, too, but heavy stuffing is for sealed cabs, IMHO.


Mark

I needed a pound and a half of fill in the Attitudes to smooth out the bump.
I see no reason, if the design calls for it, not to stuff a vented box. Just leave the vent open.

Later,
Wolf

[ROTECH]

Make sure you are talking about T/S for the right woofer. The 830875 is a stock Peerless woofer and quite a bit different beast than the 831875 that was a $30 OEM buyout here at PE. I've used both, but seen them confused in other threads.

The 830 will do about 51 Hz vented in 14 liters. The 831 will do about 50 Hz sealed in the same box, probably low 40's vented. The current specs from Tymphany on the 830 are slightly different than those I used for my build, but the boxes are effectively the same.

The 830875 in the Veepers (http://www.lonesaguaro.com/speakers/VP/Veeper.html).

The 831875 in the PeeDei (http://www.lonesaguaro.com/speakers/Peer28/PeeDei.html).

Not to get nitpicky, were you meaning the 831735 which was the $30 buyout driver?

Thanks!

[ridikas]

Mark65, what program are you using to get these numbers? Because Unibox completely disagrees with you :(

And why is there a discrepancy? All programs should model the same. We need to get to the bottom of this.

[isaeagle4031]

Programs will model differnetly based on how they are written. They do not all use the same equations to derive at their answers.

Quite honestly, based on my own experience, I am quite likely to believe Mark over the other fellow here.

I use at least a handful of stuffing in all of my ported boxes for one reason or another. At least enough to line the walls and sometimes different types in the same enclosure.

[ridikas]

But the discrepancy is huge and that should not be the case.

[isaeagle4031]

Are you absolutely sure that your T/S numbers are acurate? Are you both using the same numbers? Mark stated that the method used to derive Vas can be finicky. IF your Vas is higher, then there you go.

[donradick]

But the discrepancy is huge and that should not be the case.

Dude, build your own ARTA / LIMP measurement jig, which costs maybe about $5, and measure them yourself, then you will know which is correct.

[isaeagle4031]

Agreed!

[Mark65]

I use Jeff B's Woofer Box and Circuit Designer. If there are issues with that spreadsheet, I'm unaware of them. But by all means, if the consensus is that that is not reliable, or I'm somehow misusing it, I'm more than willing to admit that I'm wrong.

I will say, though, that I derived an F3 of 50 Hz for my Deullati using that program, and Wolf has stated to me that he believes they might be going down into the forties. Nothing measured, though.:(



Mark

[isaeagle4031]

Guess we gotta get that measured! Those just may become my front three:)

[ridikas]

I've just downloaded Woofer Box and Circuit Designer 4.5 : http://audio.claub.net/software/jbabgy/WBCD.html

I've modeled the Peerless 830875 mid-woofer and got the same values as I did with Unibox.

I'm not sure how Mark65 is modeling, but I'm sticking with my data.

I've attached a picture below. I took this measurement myself (mic on-axis with the woofer, 5mm from the surface of the cone) using JustMLS. This is a single Peerless 930875 mid-woofer mounted in a 14.6 liter enclosure. With two 1.8"X8" ports. The walls are covered with Sonic Barrier.

As you can see, the tuning frequency (Fb) is 52Hz-53Hz. If I use Ron_E's WT3 T/S data from my previous post, and model in Woofer Box, I get an Fb of 54Hz. This is extremely close and way more accurate than it needs to be. Ron_E's WT3 measurements are right on.

In the modeler, I set Rs=0.52 ohms, Ql=30, Qa=40, and Qp=80.

On a further comment to the OP... If you want to hit mid 40'sHz with two woofers in a 1.0ft.3 enclosure and have a flat response, you need to use 5"-5.5" midwoofers. I recommend Seas and SB Acoustics. With 6.5"-7" woofers it's just impossible. There might be an exception, or two, but why waste the time?

[Mark65]

No low end measurement, but this might be interesting for you if you haven't seen it:http://techtalk.parts-express.com/showpost.php?p=1801212&postcount=73


Mark


PS: I apologize for the hijack. I only mentioned my design to vouch for the veracity of Jeff's program. I won't mention them again.:o

[Mark65]

I stated how I modeled it. Twice. Read my posts. I also stated that I don't buy the WT3 vas measurement. Read them again.:mad:


IF that vas measurement is correct, and, as I already stated twice now, I DON'T TRUST IT, then I stand corrected.


Mark


PS: Feel free to direct your comments about me TO me. Talking about me as if I wasn't part of the conversation is rude.

[ridikas]

I've explained exactly how I modeled, using two different softwares. And I've backed it up with a real life measurement.

I rest my case...

[critofur]

...If you want to hit mid 40'sHz with two woofers in a 1.0ft.3 enclosure and have a flat response, you need to use 5"-5.5" midwoofers. I recommend Seas and SB Acoustics. With 6.5"-7" woofers it's just impossible. There might be an exception, or two, but why waste the time?

Could you explain what you mean by that? I've seen it done with several different ~6.5" woofers...

This one: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-832

And the Exodus Anarchy are two that come to mind.

I think 1.0 CF is just about exactly the size I'd use for a pair of these Peerless HDS 6.5" woofers. I might "boost" the bass with a LARGE cap + coil low highpass if I wanted more on the bottom... (or active eq of one type or another).

[ridikas]

Critofur, 99.9% of all 6.5"-7" mid-woofers need a 0.75ft.3 enclosure. They just don't work well in 0.5ft.3. In that small of an enclosure, you'd do well to hit an F3 of 55Hz and an F6 of 45Hz. And that's usually the best case scenario.

Why do you think Zaph doesn't publish F3 in his designs? His ZRT 2.5-way has so much peaking in the bass that it's not even funny. That design needs an 80 liter enclosure to work well.

Show me a 6.5"-7" mid-woofer, with accurate third party T/S measured data and we can go from there. Manufacturer's T/S data is usually nonsense.

P.S. The pre-built PE enclosures of 0.50ft.3 have the worst of all worlds. They're too small for 6.5" woofers and too big for 5.5" woofers. I wish PE offered a 17 liter enclosure instead. Then something can at least be workable.

[johnnyrichards]

Quit feeding him, you guys.

[isaeagle4031]

I want to Johnny, but its like a train wreck, so hard to look away.

Any way, can't get lower? Hmm I've got a set of Karma Indignias that dig down into the low 40's in .4 cube, (that's a 7" driver).

This is car audio, but I have used a pair of Elemental Designs 6's in .5 cubes that had an F3 of 35Hz and sounded very good doing it.

[johnnyrichards]

I want to Johnny, but its like a train wreck, so hard to look away.

Any way, can't get lower? Hmm I've got a set of Karma Indignias that dig down into the low 40's in .4 cube, (that's a 7" driver).

:)

[LouC]

Not to get nitpicky, were you meaning the 831735 which was the $30 buyout driver?

Thanks!

10-4 it has been corrected. I've seen the same mixup in other threads.
Now, I'm no longer perfect...:(

[ryanbouma]

Ridikas, your response plot doesn't prove what you're trying to prove. There's no port response. And it looks tuned to high if you ask me.

[ridikas]

It proves that the T/S data I'm using and my modeling skills are right on. I'm getting an error of 1Hz!!!!! And what makes you think it's tuned too low? It's tuned for the lowest possible F3 and a flat response.

I will model that Dayton woofer in a 0.38ft.3 enclosure later. I guarantee you that PE hasn't got a clue on what they're modeling.

[ridikas]

Ok, so I've modeled the Dayton DA175-8 mid-woofer in a PE 0.38ft.3 (11 liter) enclosure. More like a 9.5 liter enclosure after you take into consideration the volume displacement from port(s), crossover, drivers, etc.

I've used the T/S data from Zaph Audio: http://zaphaudio.com/6.5test/compare.html

Surprisingly, I get the same exact numbers as were described in the technical write-up by PE here: http://www.parts-express.com/projectshowcase/indexn.cfm?project=karmaindignia

So I take back my previous statement, somewhat...

However, what they FAIL to tell you is that in an enclosure with only the walls covered (i.e. Sonic Barrier), the speakers will have a 2.6dB peak at 80Hz. This to me is completely unacceptable. This will be one boomy sounding speaker.

Now if I model it with "Heavy Stuffed" enclosure. I get a 1dB peak at 80Hz. Better, but still nowhere near perfect.

Moral of the story, to get a flat frequency response, these Dayton woofers need a lot more volume and a much lower tuning frequency. As a matter of fact, they need an EBS style of tuning, which brings a whole set of other problems.

Depending on one's taste, they will give a lot of boomy bass, even in a small enclosure.

[isaeagle4031]

Hmm, mine don't. At least to my ear. Pretty flat actually. My enclosures are a bit larger at 12.5L net. 1.5"x8.5" port, radiused on the outside. Actually quite a few people have built these and do enjoy them.

[50 watt head]

quit Feeding Him, You Guys.

Omg +1