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- ani_101 5:33AM
- rjj45 5:33AM
- Steve_Lee 5:33AM
- Tieftoener 5:33AM
New Project with RS180P, Request for Advice
Hello and an early Happy New Year to all from Oz
I'm not in a hurry, but my next project will be a two way bookshelf using some surplus drivers.
I'm limited to Dayton RS180P-8s and Vifa BC25TG15 tweeters and can use WinISD to work out the cabinet and vent. I've seen a couple of projects with the RS180P and DC28F, but I prefer the sound and build quality of the Vifa and only have one of the DC28s anyway.
I don't have any measuring equipment, so looked for something using those drivers. The closest I can see would be Paul Carmody's "Hitmakers", which use the DA175. I compared the factory specs (att.) and the FRs look very similar in profile, although the RS180P is consistently 4 to 5 dB louder.
Other specs such as Xmax, qts and fs are different but I can deal with most of those issues in the WIN SD model.
I thought perhaps I could tweak that design to at least get me something to work with? If I use the factory supplied specs for the Daytons and Vifas (I used fptrace for the Vifa) , the models won't be accurate, but I will be comparing 'like with like'. I attach my first effort, which is just changing the tweeter padding.
I'd greatly appreciate any thoughts on this, apologies for all the attachments
Thank you
Geoff
Comments
__Geoff - I understand. Your RS180Ps are MUCH different than than the DA175., and I think they deserve a better tweeter, IIRC, can't you get SB tweeters reasonably?
SB tweeters are available here and good value, but I'm limited by budget.
If it becomes clear that there's a mismatch with the drivers and this isn't going to work well, I'll just need to wait awhile.
NB I posted here about a project with these Daytons a while ago and sought advice on which tweeter to use, but those plans didn't come to fruition and the budget has changed.
Geoff
If you can post your FRD files and box drawing we can easily add baffle step to them with the Blender program. We can guess at the offset and create a custom crossover in Xsim. There are a bunch of us who like to do this.
I'm gonna toss this your way just in case the additional info is helpful, or if you can obtain the beast modes easily.
http://woggmusic.com/supernova-minimus-speaker-build/
Hi there Grumpy! j/k John :-)
Hmm I don't remember saying anything about adding a zobel???
Or an L-pad! lol
Thank you all for your comments and advice, much appreciated!
I had a look at the Minimus some time ago, but the tweeter was a bit pricey here. The cabinet is perhaps too '70s looking for WAF, but I really liked the simplicity of the crossover.
I haven't drawn the cabinet yet. Baffle would be 9" wide, depth and height tbd by aesthetics. I think this would suggest a 2.5 to 3.0mH inductor for the woofer as a starting point?
The easy option would be to base it on my "Slapshot MTM" cabinet, but halved in volume, which would make the external dimensions 9"w x 11"d x 17"h, using 3/4" material. This gives a larger volume than suggested by Parts Express but the proportions look OK.
C to C 6.5" between woofer and tweeter, tweeter centered on baffle, tweeter centre 3" from top of cabinet but will draw it up - literally, as I'm hopeless at CAD type stuff.
As suggested above, here are the RS180P raw frd files from Dayton and the BC25TG files from fptrace. Of course, the Vifa graph may not be accurate.
Many thanks
Geoff
There is nothing wrong with that tweeter.
That's good to hear (no pun)!
I've used it in several builds with cheaper woofers and like its sound, but then I don't play at unfriendly volumes which might push it.
Geoff
The factory supplied FR for the Vifa may be a little optimistic in terms of dB output.
I found a graph for a measured sample and got a different curve (frd file and pic of response curve att.). It's around 2-3dB lower in dB than the factory supplied data.
I hope this doesn't confuse things; I did not use this graph for the files I posted above.
I hope the attached baffle drawing isn't too rough.
Thank you
Geoff
Update to post, I've now had an extremely kind offer of measurement and project assistance from an awesome Forum member, so please don't worry further about my request.
Thank you all for your advice and help, you guys are great
Happy New Year
Geoff
Regarding the post above...Thank you Geoff for the kind words, you have always been helpful to others seeking advice, so I'm glad I can be of assistance.
For those wanting to help, I am going to build a prototype cabinet and take all of the measurements in a replica of Geoff's cabinet with actual drivers. I will post everything here in a zip file and Geoff can use them, but so can anyone who wants to sim a crossover. But it will be in about 3 weeks.
For those who like box modelling, below are burned in measurements for two RS180P-8s as well as those from the Mfg Spec Sheet. What would YOU do?
@GeoffMillar - half of the Slap Shots is about 0.64 cf which I think you will find measures pretty good, so you probably won't be far from this volume. Regarding aesthetics, here is a comparison of your suggested box size above (W x D x H) 9" x 11" x 17" vs a shorter and deeper 9" x 12" x 15.5" which is very close to the same internal volume.
I like the look of the shorter and deeper enclosure.
Many thanks, that's very useful indeed
The shorter cabinet is almost the same dimensions as my 'mule' test build boxes, so I'll be able to mess about with parts etc until I'm ready to proceed with proper cabinets.
Value!
Geoff
I estimate driver, bracing and port will take up about 0.04 cf leaving a net 0.60 cf in the box which is half the size of your Slapshots. Tuned to 52Hz gives you a nice flat response with an F3/F6/F10 of 56/47/40Hz. (See below). Let me know if this is the box you want to use or if you want to play around with the box modeling a little. Once you decide, I'll get it glued up.
What are your options for port diameter? With dual RS180Ps the Slapshots needed a larger port than you will need for the single. You can probably get away with a 2 inch port now. A 2-1/2 inch would be better, but isn't always readily available. One thing WinISD isn't great at is modeling the port length, but if you let me know what diameter you will use I can adjust the port length until I get the right tuning and let you know what length I end up with. Let me know how you plan to line the cabinets (e.g., open cell foam, denim damping material, etc.) so I can do the same and get things as accurate as possible.
Thanks, I hadn't got around to thinking about ports but of course they're a critical part of the design.
The Slapshots have 'Precision Ports', suggested by Curt and I followed his advice on size and location; however, as per Dayton drivers, the prices are now silly.
I used the attached for my other projects:
https://speakerbug.com.au/index.php?route=product/category&path=62
The nearest to 2.5" is the 68mm (2.8") x 220mm port - not sure how the taper affects the calculated length compared to a straight pipe.
I'll go with your 'shorter and deeper' option, it looks better. The F3 etc will be fine. I usually stuff the cabinets with polyfill for pillows and put thin foam on the rear panel.
Thank you again for so much help with this
Geoff
Okay, I think this is the same port from PE. (Based on the descriptions I didn't think so at first, but Speakerbug shows the taper is from 58mm to 68mm which averages 2.5" vs the 2.8" of the 68mm end.) I will use this port and cut it down until I get a perfect 52Hz tuning. (Unless you want it tuned a little high/lower, which will increase/decrease the modest 0.5dB hump in the plot above.)
52 Hz looks fine, thank you
Geoff