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Ross Systems H-218CD speakers anybody? Mine are missing tweeters.
Ross Systems H-218CD speakers anybody? Mine are missing tweeters.
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Old 13th February 2018, 05:21 AM   #1
ericj is offline ericj  United States
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Default Ross Systems H-218CD speakers anybody? Mine are missing tweeters.

Last night i brought home speakers with a lower WAF than any i have personally had an opportunity to own. Good thing I'm single.

A bar in salt lake city wanted to get rid of them - story was that they were bringing in a new house band that had their own gear that they wanted to use in the rehearsal space upstairs and these were taking up a lot of room.

I paid zero dollars. I just had to show up before 9pm and make them disappear. The pair of them just barely fit in the back of my '94 land cruiser. Stacked on their backs.

I'm told that bands like Slaughterchrist and Evil Innocence gigged with them in the 90's. I was offered an opportunity to meet the guy from Slaughterchrist, who was just upstairs, but, passed.

If i use my speakers that were used to disperse death metal with my cables that were used to produce donna summer albums, does some kind of a portal open? I guess I'll find out.

I don't have pics of mine yet (sorry) but you can see some shots of the somewhat smaller H-215CD here:

OBO P.A. Spkrs ROSS Hurricanes (pair) Saanich, Victoria

I understand that Ross Systems was a flash-in-the-pan brand headed by Bud Ross of Kustom fame. That these were made between 1986 and 1989 as that was pretty much when Ross Systems existed. And that these were the top of the line - they were mentioned in some magazine as a new product, per google.

They're in pretty reasonable shape. The grilles need some hammer time and some rustoleum and some additional mounting hardware imho. Some boob pushed in the domes on the midranges (the big horn) and today i discovered that the midrange horn is affixed to the front baffle, and to a bracket that is bolted to the top of the enclosure, and i needed more wrenches than i had at hand to extricate it. I'll try the gaffer-tape-on-a-stick trick tomorrow maybe.

Thanks to the Utah Indoor Clean Air Act they do not smell like an ashtray. The carpet isn't even ratty - just a little bit beer stained. I'm considering borrowing mom's carpet machine and using the upholstery wand on them. A little work and they'll look 25 years younger.

The cabs are 5/8" plywood, and not cheap plywood either. There is substantial internal bracing.

Some gut shots of one of them here:

Ross Systems H-218CD - Google Photos

I'll add more photos to the album over time. And yeah i noticed that a resistor appears to have been on fire at some point.

They seem to mostly work. some of the connectors need some deoxit and maybe a rifle brush. I am pretty sure that speakers rated at 1kw RMS maybe ought to have internal wiring fatter than 20ga. I have already ordered new 'lytics from madisound.

Thing is i just have squares of masonite where the dual tweeters should be.

My guess, based on the vintage, is that they may have been the motorola piezos that were so popular back in the day.

Does anyone actually know? Parts Express sells a Goldwood horn that is the spitting image of the tweeters in the rest of the Ross Systems line. I can't find a photo online of an H-218CD. PE also has at least 3 piezo tweeters that claim to be clones of one specific Motorola piezo tweeters, and opinions of them would be welcome.

I'm also aware that those horns might not provide full or loud enough treble next to the other drivers. But lacking specs -- and i really lack them -- i'm guessing here.

Last edited by ericj; 13th February 2018 at 05:28 AM.
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Old 13th February 2018, 10:45 AM   #2
chris661 is offline chris661  United Kingdom
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Cool find!
They look like they'll be fun speakers. Not the 4" audiophile ones that only with girl & guitar music, but something to rock out with.

With regards to the tweeters, you might just find they're not necessary. It looks like there's a 2" compression driver on a large horn, and you might find that runs high enough into the treble to keep you happy as-is.
If not, I'd take a look into using something like an Eminence APT150 rolled in above 5kHz or so.
I'd avoid piezos unless you're willing to do the work to make them sound good. They do not sound good right off the bat.

EDIT - looked at the photos again. Looks like a 5-6" mid on the horn, so you'll need the tweeters. I'd look for a 1" driver good for 2-3kHz, and a horn that fits the cutout dimensions. One per side will do the job and likely sound better than using 2 per side, but if you want them to look right, install a couple of extra horns.

If you can write up a list of drivers that are installed as well as a crossover schematic, we'll have a much better idea of what's going on in there.

Chris

Last edited by chris661; 13th February 2018 at 10:48 AM.
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Old 13th February 2018, 04:19 PM   #3
ICG is offline ICG  Germany
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Location: I had a Déjà Moo - I've seen that BS before!
Yes, that are piezo tweeters and a 6" mid driver. Different tweeters are a must, the rest is likely fine though. You have to modify the crossover and that's not that easy. Do you have any measurement equipment?
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Old 13th February 2018, 06:02 PM   #4
ericj is offline ericj  United States
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The woofers are house brand, all i know is the numbers i photographed. Ross just called them L18. I don't expect to find much on the midrange.

Treble is absolutely lacking.

I mean, it's ok as part of a bass guitar rig, but yeah.

Measurement tools? Various multimeters, 1hz
to 2mhz function generator, 12mhz scope, etc.

I have one of those panasonic mic capsules and keep meaning to make a speaker measurement rig.
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Old 13th February 2018, 07:20 PM   #5
ericj is offline ericj  United States
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I have a Kustom KM100 keyboard amp here that came with a piezo tweeter that looks a hell of a lot like some of the cheap piezos that PE offers are motorola replacements, and it mostly just produced some hiss at the very high end.

Kustom hadn't used any kind of crossover network but i don't think that would have suddenly given me full treble.

I had pretty good results replacing it with a Pyle PDS442 and a PRV horn that fit the cutout, along with a 12db/oct crossover at 3khz. I need to go back in to adjust the values a bit because i seem to have a hump right around 3khz. Just by ear, playing with the knob on the function generator. I will probably bump it up to 3.5khz or so.

Like i said, i am betting that when i extract the midrange from the horn-and-hat deal, it will not have any meaningful data on it. just house numbers.

At this size, the perceived bass level is highly dependent on the size of the room, right?

So it's the midrange driver that the tweeter really needs to be matched to.

If i measure it, probably the entire midrange horn assembly as a unit, i should be able to determine it's efficiency and then match tweeters to it.

How involved might that be? I have never measured speakers before but i have aspired to and i think i have most of the gear.
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Old 13th February 2018, 08:03 PM   #6
ndcraig is offline ndcraig
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Quote:
Originally Posted by ericj View Post
Does anyone actually know? Parts Express sells a Goldwood horn that is the spitting image of the tweeters in the rest of the Ross Systems line. I can't find a photo online of an H-218CD. PE also has at least 3 piezo tweeters that claim to be clones of one specific Motorola piezo tweeters, and opinions of them would be welcome.

I'm also aware that those horns might not provide full or loud enough treble next to the other drivers. But lacking specs -- and i really lack them -- i'm guessing here.
Put "piezo horn" into Ebay search and came across this:

NEW Pair Of MR DJ TE-180 4"x10" 300 Watts P.M.P.O Piezo Horn Tweeters | eBay

Looks to be a clone of the one I remember from way back that looked like the ones in that picture you posted of the H-215.

I would definitely recommend a single unit similar to the Eminence APT instead.

Your woofers look to be stamped-frame Eminence that were oem'd for Ross. Probably safe to say the mid horn is an Eminence sealed-back unit like the Alpha 6.
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Old 13th February 2018, 10:40 PM   #7
conanski is online now conanski  Canada
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LOL.. Did the cat come with the speakers too? He/she looks to be roughly the same dusty color.

Yeah piezos were common back when these things were created, I'm avoiding saying designed because the driver layout all wrong... but then these are from a guitar company. And they would need two of them to keep up with the other drivers.. piezos aren't terribly efficient. Based on my own experience with them I'd suggest substituting a dynamic compression driver super tweeter and modifying the tweeter crossover to something in the 5khz range... depending upon test results for the midrange of course.
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Old 14th February 2018, 12:44 AM   #8
ericj is offline ericj  United States
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Yeah these look pretty much exactly like the tweeter waveguides in the pictures of the H-215CD and others:

Goldwood GT-400PB 1" Horn 1-3/8"-18 TPI

Fits the cutouts in the baffle too.

If i select a driver to use with that which is bigger in diameter than 4-3/8", I can fab up some spacers to angle the tweeters left and right by enough degrees so they clear each other in the cabinet. Shouldn't be a huge deal - glue up a couple boxes and miter cut them.

Last edited by ericj; 14th February 2018 at 12:47 AM.
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Old 14th February 2018, 05:39 AM   #9
ericj is offline ericj  United States
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Quote:
Originally Posted by conanski View Post
LOL.. Did the cat come with the speakers too? He/she looks to be roughly the same dusty color.
That's just my lab assistant Rama. He's always skeptical of these projects.
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Old 17th February 2018, 10:49 PM   #10
jefflaf is offline jefflaf  Canada
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Default Ross Systems H-218CD

I have a pair of these Ross Hurricanes. I am not sure if the previous owner replaced one of the speakers but I notice they don't sound the same between the two of mine. I have the same issue with some idiot poking in the mid-range dome. Do they sound phenomenal? No. Do they sound bad? Not at all. Decently impressed by these old beasts.
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