RV build TL, OB, Horns, Top horns with TL or OB bass, sub or no sub?

Good question🙂

My Edgarhorn speakers are rated at 99db sensitivity, 99db at one watt, they take little power to get quite loud, I have a 10 watt per channel amp I used on them. I am replacing the bass lower section with something that fit into the space much better and wanted to go lower than the 80hz they produce. Something close if not at 99db with 1 watt input so I could play the whole system on the same amp channels which is asking for quite a lot I know when going lower in frequency. Not sure that is possible but was looking into it and asking for advice on how to get there. Then again, wanted high SPL like the horns that will be on top, not used often but like it when I can do it🙂

Trying a different way now fully aware it might not work out but seems like a fun easy to build project, the eight 8" driver SLOBs which are going to be quite compact sitting under the horns, I do not know how they will do with the 10 watt amp running the horns and them together and know the crossover at a minimum will need some tweaking but I am prepared to go active and run a second amp for the bass units which should really get it on with enough power applied and just might go low enough to not need a sub which I hope is the case.

If the SLOBs and/or the horns do not work out I will come up with another plan but have to try to get the horns setup well and hope I get lucky with it all🙂

Rick
 
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AllenB, I did not see your last post until just not for some reason.
Everything in the RV remodel has been fine tuned to give maximum ulitlity combined with the style we like, added insulation, etc...down to the minute detail and there is simply no good place for multiple small subs. I like the idea and if in a house it would be something I would seriously consider, or an RV I had not so carefully planned out.
I have had a mental block for some reason and just not able to get my head around hornsrep but I will continue looking into it. That and I like doing something different than I have done before as well as can make different test enclosures pretty easily as have lots of time, once the weather is good because I work outdoors and winter is here now. I want to try the SLOB just because it is cool in my viewpoint, pretty easy to do, low cost...and might not need a sub at all.
I will check out the link you posted next, thanks!
Rick
 
I am replacing the woofer section with something much smaller than that part of the Edgarhorns that covered 80-300hz with what I hope turns out to cover at least 30-300 but might do better and get down to around 20 then up to 300 and leave more open space in our 430 sq ft RV.

You are making me rethink a bit of this which led me to consider when I redo the flooring I plan to drill access holes to blow in more insulation. I have to be careful due to water tanks, hydraulic, water and electrical lines, furnace ducts, etc....the chassis is 12" deep but only the bottom few inches are insulated so I plan to fill all the voids. I could fish speaker cables to areas now unreachable and build in small subs into the floor, bottom level of a cabinet, etc....I just did not think of this until you brought it up, thanks🙂

I still hope to not need subs and I do have a to support the horns, huge crossovers, etc so going to take up some floor space. The Edgarhorn bass sections are 14.5 wide and 21 deep and approx 36 tall, the SLOB to replace them would be more like 13 wide, 14-15 deep at the most, 32 tall. In our tiny living space that does make a difference🙂

I want a solid bass section capable of pretty high SPL, the Sd of the eight 8" drivers under each horn would be around the same as two 15's in a tiny space. I would still have room to fill in the bottom with sealed subs if needed.

If not for wanting to use the mid/tweeters of the Edgarhorns, not sure if you saw the post Dr Edgar was my friend, I would do something quite different indeed and most likely a single driver system and if possible without subs but subs if needed.

Lots of great and affordable drivers available so I might end up building a number of test speakers over the next few years until I find something I fall in love with and then build a really nice set of them. Or, I might just keep testing different things as I always need a hobby and audio has always been a part of my life, cars to but I finally burned myself out on them a few years back. I do still have a 400HP Fiesta ST with fully built suspension, BBK (big brake kit I developed) drivertrain, big turbo, big cooling, etc, $50k into a Fiesta I did all the work on and built the majority of parts for. I have not driven in 4 years. It was planned to be my last project in 2014, 1,000 hours into it, no longer interested in such things and no longer that kind of funding but speakers and other audio gear can be done for pennys in comparison, or nickles, dimes and quarters to the dollar at least.
 
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I did not state that well. The huge crossovers are in the Edgarhorns, mostly it is the very large oil filled mil spec capacitors, the inductors are flat wound copper ribbon and good resistors, point to point wiring, good terminals. They will be built into enclosures at the back of the horns as they are now but much more streamlined and modern looking. They will make no significant difference in using up floor space but the bass modules do so needed to make something much smaller.

Searched but came up with no answer as to how much power I would need for the SLOB setup, I guess I just did not use the right search terms🙁 I had only read, in many places, about OBs that use very little power.
 
With open baffles the front and rear energy, which is out of phase, meets and cancels to some degree. The lost energy is compensated for by way of increased excursion from the drivers and increased power from the amp.

The bass region is where this becomes significant. Here is a model from Siegfried Linkwitz site.

dip.png

The woofer is 8" and the baffle is 16". The axial pressure loss at 20Hz is 29dB. For a conventional closed box it is 6dB (a 23dB difference) (and it is flat all the way rather than sloped). This means you need about 200 times the power at 20Hz for open baffle, plus the excursion, and you have to equalise to get it.

If you look at the plot that xrk971 posted, the bass is down around 31dB at 20Hz after reaching its -3dB rolloff point at around 80Hz.

1651185947134.png
 
Yeah, I don't see the advantage of OB in an RV, better to use the drivers in a sealed box and EQ it flat/whatever to best blend in such a space.

If you bought the GRS 6PR-8 with a calculated 85.21 dB w/m (assumes T/S are accurate, which in my limited experience the brand is way off and not in a good way), then to get to 99 dB requires 99-85.21 = +13.79 dB, 10^(13.79/10) = 23.79, so (24) of them/channel.
 
Thanks very very much!!!!

I ordered the GR8PR-8 not the 6

I am OK with something like 30hz, is that feasible with my situation or still asking to much?

I can add EQ, a good amount of D class power, if worth it, I can run 12 volt amps and get good deals on quality ones.

Sincerely,
Rick
 
OK, same calc'd eff = same (24) drivers/channel.

30 Hz? If still planning on a SLOB, don't know the math to calculate, but the driver's max flat tuning in a sealed box = (0.707*52 Hz Fs)/1.11 Qts = ~33 Hz, but this assumes a negative ~36.2 L sealed box, so the box could be just big enough to house them and DSP it to a flat 20 Hz/whatever Fb with the understanding that between tuning it below Fs + minimal Xmax it won't make much peak SPL, maybe not even the 99 dB since that would be a mid-band, not Fb, tuning eff..
 
Thanks again, much appreciated!
I believe I will go ahead and build the 8x8 SLOBs because I will enjoy the project and it will not cost much nor take much time to build. If subs end up being needed then will add one per side behind them as I can build them partially into the yet unfinished wall so they would be very shallow but large enough area for plenty of air space even for the 15" Image Dynamics I have on hand which are very good subs. If for some reason the SLOBs just do not do what I need I will build something else, love building stuff, always have, always will🙂

I will stick with 110V amps though I considered 12v when doing the 20" length extension to the RV but recalled why not. It would of been a 35ft run with at least 00 wire, which I have on hand, but that is a very long run and I have two dedicated 110v properly twisted and shielded circuits just for audio, one 20 amp and one 15 amp but wired with the next gauge up so could be 30 and 20 amp circuits. Though not needed I just wanted bigger wire since going to the considerable effort to use a 3 wire twist and run the lines in separate conduit that does not touch any metal in route and at least 2 ft from each other, conduit not connected at outlet end to the outlets. I still need to look into AC filtering as well, saw the nice boards on the site here, etc...needs to be DIY unless something good that is very affordable is available pre built.

Not sure how long the rest of the full remodel will take and how long for getting what I want for the audio system, I keep saying just 1,000 hours to go and put in twice that this year so far but I will always need a hobby and have a lovely wife that supports me and loves audio even more than I do🙂

Rick
 
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RAAM,

I am watching this thread with great interest. I consider it a unique challenge to achieve the goal intended. Fortunately, you have the knowledge and needed computer skills to model the ideas that come to mind. I am shooting from the hip here, but it occurred to me to ask if there is a possibility of using either a floor or wall as a baffle for the sub-woofer. I have long wondered of this concept even for a house listening situation. Seeing as you are in the remolding stage, this would be the most appropriate time to consider this.
Also, I would like to mention that I have built both the original DNA and DNA2 and would also guess that neither would work for your situation, as you have already said. I found the DNA to not go down that low, and so built the larger model in hopes that it could compensate for the rest. Depending on the drivers used it mostly failed in the bottom octave, and only the Scan Speak 18W driver excelled. Too much money in my humble opinion, yet what was I to do when a customer gifted me with a pair?
 

Ixnay,​

Thanks for the compliment but in this case I am relying far more than others than myself as they have far more experience in this area than I do. I have had more hobbies and interests than I can remember, started at a very young age and never stopped. I just had the belief there was nothing I could not do if I put my mind, and body, to it and have huge success nearly always. I consider myself, in most areas, a jack off all trades but master of none except maybe bating🙂
I have been blessed to meet many amazing true masters that all were glad to share what they knew and guide me along then I just got busy and did it, often times finding little aspects to make improvements to end results or how to get there then would share them with others. I have come up with original ideas, at least to me, many times as well.
I have also gone off track many times but in the end I still learned valuable lessons and or added to my skills so was still worth it. When I got into car audio competition I went kind of nuts but it was my therapy after a heartbreaking divorce where my beloved children were suddenly 1500 miles away, it was nearly the end of me. I jumped in feet first, rebuild the entire system in my backyard, 5 times in less than a year, 4th system, 5th competition, beat a prior world champion that had a huge shop and big money clients, in front of two of them. That was payback for laughing at me when I said I was going to go for the title 5 months earlier when he beat me with a basic but nice street system in my Tacoma. Then I rebuilt it completely again and two months later he showed up, sans customers, in a brand new vehicle and high end system to beat me, I still won🙂
All that said, I leaned how to do so well from listening and following great advice, primarily from Eric Stevens and Matt Bougart at Image Dynamics, two dang fine people I am honored to know. That is where I met Dr Edgar as well, another great guy and teacher. I put in many many hours and developed my own line of sound deadening at the same time, average sleep 4 hours a night that year and the next but worth it in every way.
Rick
 
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Rick,

In some ways I can relate to you. I appreciate your sharing life's experiences. Starting at an early age, I was enticed by all things sound. It was all around me, and my only confusion was that it seemed most of the rest of the world couldn't or wouldn't hear it. This naturally led me to all things audio, but most of the time, I was underwhelmed. Like you, I had to learn the hard way that if wanted anything done right, it really was up to you. Hell, I didn't want to change my own oil or do my own mechanic work, but often times it was just as well that I did. Unfortunately, we are often times at the heel of professional need and must trust those who are licensed to do their jobs. It can work out beautifully or not.
The fact that you know when to listen and then consider the advice from its source (and the source as well) tells me that it pays off.
 
I agree completely! I have paid top "experts" to do a job I did not want to do, turbo systems, roll cages, very few car repairs...and none ever did it right so I would buy the tools and do own even when I had plenty of funds to pay to have it done. I have actually had to completely rebuild two turbo systems, had two shops blow up engines that should not of done so, cut out a "roll cage" so poorly done it was a death trap and my first attemp past the most stringent inspection in racing I know of. The first time, a very long time ago, that I paid a shop to fix a car I did not have a place to work on or the tools the morning I picked it up the fan came off, trashed radiator and opened the hood as broke the latch, ruined the hood, broke the windshield and I stopped 10 from running into a telephone pole.

I go against advice at times knowing it probably will not work and sometimes not, sometimes it does, sometimes better than expected or hoped for. I do listen as we both agree upon and as I said I sure appreciate the help I have received here and will admit if things do not go that well🙂

I may of mentioned this already, built my first speakers around 1966, installed first car stereo in 1968, just about finished the office/audio extension project but ran out of time to side it before winter hit to hard. I am going to make my own Shou Sugi Ban siding for the whole RV including thin material for the ends of the slides. I only moved the wall in the drawings, no new plans, just built the new steel frame, side and end wall, toughest parts were the frame and curved roof. I was up and down the ladder, 13ft high roof, 20 times some days, crawling under the unit many times some days, not bad for 70 and still waiting for the VA disability determination, I pay the price in a lot of pain but I just deal with it. Craigslist most everything, around $5-6 k in materials and probably 120 hours or maybe much more, I have less than $1k into it.

OK, getting a bit off track here, to say the least, I did all this for two reasons, better windows and views and room for a decent audio system. Next year I get to play with speakers but also have a ton of cabinets to build, more than many houses I have been in, 2cm Brazilian green soapstone counter tops to install, other end of the RV to rebuild like this end I am sitting in, a few more windows to change out, a huge amount of work on the siding....if only we get a good summer again without smoke, the heat this year was bad enough but I got in 6-9 hours everyday.

And I get to play with speakers, design fold down TV mount, maybe DIY amp(s), Xovers, cables, etc....
 
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Dude,

You know why I am laughing. HA, the pain is worth it...unfortunately. Your first description of car repair sounds about right! But then as you also know, the knowledge of some doesn't seem to extend to the fingers.
Don't forget to pick your battles though. I tried many years ago to tell my sons this, but they don't listen.
 
GM,

Thanks for the reply. First time that I saw this as a concept was before my time in the 50's one guy had the idea to use a closet door for the 'sub' baffle. Hmmm. Doors were solid in those days.
RAAM, do you have a closet on the other side of a wall?
 
You're welcome!

Yes, often used as IB for the large full range 15" RCA, Altec 600 series coax and similar that ideally required huge cabs 'to be all they could be' when coupled to impedance matching and/or various DF tone controls tube amps.
 
I decided early on to just do my own thing as far as my children were concerned and invite them to participate if they wanted to. I used to pay my son, now 34, $20 to help me build computers for my customers, I only built a few a month as it was a side job, full time Navy back then. He was 4 or 5 years old so not a great deal of help but he loved it and it helped him learn to be self sufficient and he is though not into building things he can fix most anything, very proud of him🙂 One daughter into music and acting but wise enough to know to keep it mostly hobby, she is good but that is not enough in that tough industry but I always supported here, bought her gear she wanted to try out, etc...My eldest daughter loved math, has a few degrees, is a CPA but got burned out at a very tough job so taking time off from it. I did advise her to take an easier and higher paying job but she loved the challenge as has been told many times nobody else could do what she was capable of. They each have their own level of "success" which I always advised was doing what you love to do no matter how much or little you made at it as long as you had enough to live on decently.

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No doors here but quite familiar with IB and was going to do it in a 53/05 Studevette project I was building, panels behind seats covered fuel tanks on each side, switch to a fuel cell in the trunk floor and have two 21" subs, with custom wound voice coils by Eric Stevens. The tiny dash was perfect for building in two huge horns, drivers above the very deep foot wells, horn mouths would of been very wide and fairly tall. Under the horn drivers the foot wells were covered with a panel that had enough room for an 8 or 10 on each side, would of used frame rails, etc for more air space as needed, horns not quite enough space so possibly OB, it was not fully sorted out when decided to sell off everything and go RVing full time.

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RV, started out with a toyhauler with a 400HP fully built street/track/site seeing Fiesta ST in the garage, still have the car but parked for a few years, just not into it anylonger, need to fix a few things and sell it. Sold the toyhauler and bought this Teton as the very best chassis ever built, got it cheap, was in great shaped but we are changing at least 90% of it except chassis though I did make that longer by 20" 🙂

I tore out the interior leaving the fiberglass cap and was going to add layers of glass, embed the sides, top, etc into it and use the floor, part of side wall, etc for the enclosure. Also going from three windows to one big dual panel Anderson casement window but it ended up far more difficult glass work than I cared to do so just tore the end off the RV, built new steel frame, super insulated, new side wall extensions and back wall. It ended up being a lot more work than imagined, always is, but gained much more room to add another door, floor space and audio space so well worth it and though tough at times great fun!

Might be the only RV with a 30x60 free standing oval tub we both can fit in😉 Certainly will have one of the best audio systems in an RV as well.

Rick
 
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