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Budget 18s in gsub?

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bmholbro View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bmholbro Quote  Post ReplyReply Direct Link To This Post Posted: 21 March 2018 at 3:05pm
Markie--I don't disagree with your comments and have no intention on making additional cabinets with these.  I had a budget Yamaha dual 18 with a couple of failing drivers that I thought I would see what would happen with these things. The box cost me $300 used years ago so its not worth putting anything proper in them. 
My current G Sub build will be loaded with L18P400 drivers. I had considered loading RCF's into this cabinet but if I invest in the extra drivers it won't cost me much more to build another pair of G Sub boxes.   This cabinet is made of particle board so would probably take a lot of work sealing and bracing.  Additionally, the G sub is slightly shorter than the Yamaha cabinet which I like.  By my measurements I can squeeze 4 G subs in my Expedition because of this difference.  I do a number of events at venues with adequate house sound if I just drop subs in there. 
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 21 March 2018 at 6:49pm
Doubt you're going to get the performance of two drivers with 5.5mm xmax, but this topic has been done to death already!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bmholbro Quote  Post ReplyReply Direct Link To This Post Posted: 21 March 2018 at 7:03pm
I'm sure.  That said, I am replacing a driver that isn't exactly spectacular.  I think the Yamaha driver has an XMax of 6mm and is rated to handle ~600RMS with a similarly light 3" VC. 
Haven't wired it yet, but looking at it closer the cone is definitely shallower and there is little to make me think this will surprise any of us. 
 
With what the 4 L18P400 cost me, this is cheap fun.
 
  
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JonB67 Quote  Post ReplyReply Direct Link To This Post Posted: 21 March 2018 at 7:08pm
Pretty sure that comment was aimed at markie not you.

But as markie said he hasn't read the whole thread.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bmholbro Quote  Post ReplyReply Direct Link To This Post Posted: 15 April 2018 at 2:53am
Finally loaded both Rockville’s in the old
Yamaha cabinet. Tomorrow I’m taking them to an outdoors park party where I should be able to give them a nice open air test.

I did hook the cabinet up to the Inuke amp and confirmed it made sound etc, but I was in the garage and it was a little late to push them. At a fairly minimal level I played the Yamaha with the Rockville and one of my RCF loaded G subs just making sure both were sound to play. 

Quick thoughts:
—For lighter drivers the Rockville’s don’t move as easily as I would expect them to and clearly don’t have the Xmax the RCF does. 
—with gains set the same on the identical amps, the G sub definitely had a more pronounced sound and was louder. This was expected versus the stock Yamaha
—nothing sounded “bad” .... Definitely did not have any issues playing in the mid 30s when I did a couple tone tests
—thankful for the foam in my Yamaha’s so I don’t have to look at the cheesy logo on the cone of the driver

Will give you guys feedback on the open air test tomorrow. I won’t be able to max anything out tomorrow but should be able to get some decent volume. 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 15 April 2018 at 8:30am
Quote with gains set the same on the identical amps, the G sub definitely had a more pronounced sound and was louder.
Most interesting result! Depending on what you mean by 'louder' obviously. With low frequency test tones or with music?

If you enter the Rockville TS parameters as published and simulate them, they actually appear to be very efficient (100dB/Watt), but if you look at a lot of other budget 18" drivers in the same (or lower) price range, a 93-95dB/Watt sensitivity rating is quite normal. (RCF L18p400 is 97.5dB/Watt)

Measurements, even really rough ones with whatever mic you might have laying around (quality of frequency response not so important) might help if it's hard to articulate the difference in words.



Edited by Hemisphere - 15 April 2018 at 8:31am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bmholbro Quote  Post ReplyReply Direct Link To This Post Posted: 15 April 2018 at 1:26pm
I will bring my portable recorder. The more applicable side by side test is supposed to be Yamaha stock versus Yamaha with Rockville—I just happened to have a Gsub with the grill off next to it. 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 15 April 2018 at 4:07pm
True - the Yamaha's are 70 litres external larger than the G-Subs so they're probably tuned lower and would be a bit quieter, but they may also have tuned them to have a peaking response at cutoff so all bets are off until a like for like test

Actually the -10dB points of those cabinets are the same according to the specs, obviously that will be driver dependent. If the Yamaha is taking 70 more litres to produce the same f10 that's probably the driver's fault (cheaper drivers usually like bigger enclosures).


Edited by Hemisphere - 15 April 2018 at 4:10pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bmholbro Quote  Post ReplyReply Direct Link To This Post Posted: 15 April 2018 at 8:38pm
at the event now... when I did a side by side I couldn’t really tell a difference between which Yamaha had the stock or the Rockville drivers. We are only running the whole system up to about 118 db so not pushing either cabinet set to its limits. 

The GSubs definitely are a much more solid box than the Yamaha’s in terms of the vibration you feel on the cabinet at this level. The Gsub stack is about 25% louder when the amps are matched at he same level settings—I played with the levels to even both out.

Will do a quick measurement of Yamaha vs Yamaha to see better than my ear test—I’m actually not sure which cabinetnis which without looking at the serial numbers.

I feel better about the Rockville experiment now though... they at least seem to do what the Yamaha did for the typical event I do. I’m not sure how often I will use the Yamaha cabinets, however, as my truck only fits 2 dual 18s with my mains. If I used 4 cabinets often I would definitely make another pair of G subs and load with the RCF....

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Post Options Post Options   Thanks (0) Thanks(0)   Quote LunchieTey Quote  Post ReplyReply Direct Link To This Post Posted: 06 May 2018 at 12:19am
Originally posted by Hemisphere Hemisphere wrote:

Actually the -10dB points of those cabinets are the same according to the specs, obviously that will be driver dependent. If the Yamaha is taking 70 more litres to produce the same f10 that's probably the driver's fault (cheaper drivers usually like bigger enclosures).

Cabinet volume doesn't dictate tuning. Just because the Yamaha is 70L bigger does not mean it is tuned lower or goes lower. 

Same with the f10 point. A higher port tuning(common on commercial cheaper subs to fatten up the 60hz area) will mean f10 will be higher. A large box tuned slightly high gives a lot of 60-80hz which is helpful in selling cheap gear to inexperienced users. It's not necessarily a result of cheap drivers. A cheap driver can be made to go low in a big box quite easily. Power handling and efficiency obviously may suffer but the c218v is not a huge power box.

Yes VERY cheap 18s have trouble going low but even a Dayton PA460 can do sub 30hz with the right box(ar the expense of output)

Contrary to the opinions of most guys who run huge systems, 95% of the population can't pick or even care if a system has a -3db cutoff at 30 or 40hz. They're all off their faces focusing on trying to have fun or pick up women/men. This is the real reason most 'mobile' 18s from large companies(Yamaha JBL etc) have fairly high cutoffs. Small is popular as well as thimping 50-60-80 hz sells more boxes to young DJs than a flat to 30hz response with a loss in output. The high turning also gives s lot of mechanical power handling at kick frequencies for usual top 40 music.

Exactly the same reason cheap car subwoofers are all tuned to 40hz or so in prefab boxes. They 'sound' louder at the expense of the extreme low end.

Interested in the Rockville results. Have a use for a cheap 18 in the near future so would be interested in any measures results or even a direct comparison to the Yamaha. If they match the yamaha drivers, for the cost that's all I need. Making a smallish house party system using a pair of plastic(debadged) skytec boxes with new far better drivers with a crossover I will design using measurement and some form of sub. Rockville do a 4 ohm version so a single would run well off one amp channel. A quick blast with black spray paint will deal with the logo.


Edited by LunchieTey - 06 May 2018 at 12:38am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bmholbro Quote  Post ReplyReply Direct Link To This Post Posted: 07 May 2018 at 8:27pm
Hi Lunchie--I don't know when the next time I will be able to pull these out in an A/B setting.  Based on my last outing I would not hesitate to throw one of these things in a small party box in terms of output and "going low". 
 
I could not tell the difference between the Yamaha and Rockville without looking at the serial #'s on the back.  Both cabinets seemed to hit the same volume when I played them side by side in the park.  The only thing I noticed was that when they were in a stack together there was a bit of muddy sound from this stack versus my G-subs. I assume this was because this stack had different drivers in each cabinet. It was fairly slight but audible. 
 
The driver itself is slightly lighter than the Eminence and has a kind of plastic feeling dust cap. The banana plug connections on the drivers also were a bit odd to find and something I added a dab of silicon on top of to keep it in place.  They state 900W RMS handling and I am sure this is inflated, but I expect it safely handles what the Eminence does.
 
Don't mistake this for a ringing endorsement for the drivers, simply a statement that I would spend $70 on them before I spent $160 on one of the Eminence drivers.  If I had to do this over again, I probably would have just re-coned both stock drivers so I had a matching stack and maybe better resale but doubt the resale would cover what the repair costs.
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LunchieTey Quote  Post ReplyReply Direct Link To This Post Posted: 09 May 2018 at 6:07am
Nice,  thanks for the feedback. If they are as good as an average sub driver from a mid level name brand cabinet or at least close enough then that will do me. Being in Aus makes drivers either hard to ship or local agents want stupid money. For example, a base level 18 from a better brand from a dealer here is about the same price as a decent B&C shipped from overseas off ebay. There are also very few supported brands as well.

I pay basically the cost of the Rockville in shipping but it still works out a good deal here. It's around $300 for a bottom end 18 from eminence(delta pro 18) the Rockville would be a bit under $200au. There are a few Chinese drivers around for similar money but not sure about them until I can find anyone who has used one.

Either that or I just put extra cash away and go for a TBX100


Edited by LunchieTey - 09 May 2018 at 6:16am
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