SQ & output of a Tumult VS a Contrabass & a few Contrabass questions

James W. Johnson · 01-14-2004, 11:59 AM

I know the Contrabass is not necessarily a DIY subwoofer although kits have been offered in the past but it seems I have met a few Contrabass owners here in the past.

By days end today or tomorrow I should have a tracking number for my Contrabass subwoofer. I found a deal that I could not refuse so I jumped on it.

I was just about to pull the trigger on a Tumult subwoofer though so now I will wonder what I am missing ,likewise if I went with a Tumult I would wonder what I was missing with the Contrabass. The Contrabass deal will most likely never happen again though so I had to go with it and as
a bass enthusiast I will feel more complete having tryed out a Contrabass.

How will the output of a Contrabass compare with a single Tumult?
I was going to seal the Tumult in around 3cuft and based on what I have read about it I am fairly confident that this subwoofer would be very satisfying for both music and movies.
How does the Contrabass perform in the music department?

Lastly , I am putting the Contrabass in my 8.5' x12' HT room , as I understand it I am going to have to EQ the heck out of it and buy an amplifer that can drive anything.
What is a good amp and EQ for the Contrabass?

ThomasW · 01-14-2004, 02:26 PM

HTF member GM, Greg Monfort either has or had Contrabass bins. You might look him in the members list.

Normally I'd say your room is too small for the size of the Contrabass cabinets, but that may not be the case given your 'Bass Pig' cabinet design.

As for which is 'better' Contrabass vs Tumult, probably only Mark Seaton, or Dan Wiggins is in a position to say

Greg Monfort · 01-16-2004, 02:41 PM

>By days end today or tomorrow I should have a tracking number for my Contrabass subwoofer. I found a deal that I could not refuse so I jumped on it.

====

ServoDrive or DIY unit? New/used? If used, by whom, and for how long? The reason I ask is because that while they can take quite a bit of abuse, once the belt system gets worn it must be completely replaced. If the motor is in tough shape and needs replacing, then you're looking at ~the cost of a Tumult, or at least that was the replacement cost back in the late '90s. The cone 'drivers' and PRs are fairly bulletproof, so short of someone carving up the surrounds, they should be OK.

If DIY, some were assembled wrong due to a lack of info initially, others had cabs with the wrong offsets due to an error in the drawing provided and some folks just respaced everything to make it work, putting additional load on the belt system.

====

>I was just about to pull the trigger on a Tumult subwoofer though so now I will wonder what I am missing ,likewise if I went with a Tumult I would wonder what I was missing with the Contrabass. The Contrabass deal will most likely never happen again though so I had to go with it and as a bass enthusiast I will feel more complete having tryed out a Contrabass.

I was going to seal the Tumult in around 3cuft and based on what I have read about it I am fairly confident that this subwoofer would be very satisfying for both music and movies.
How does the Contrabass perform in the music department?

====

Assuming it's in good condition, the only subs that I'm familar with that can begin to compete SQ wise is a huge basshorn or extreme IB such as TW's. I haven't seen the distortion specs or auditioned a Tumult, so can't offer any opinions on it, but I would be surprised if any point source driver can compete that's not compression loaded.

The CB OTOH has such low distortion that one guy over on HTT described it as 'overly dry'. According to Tom Danley, they normally only fail in use because the FOH engr. will keep boosting them to destruction since he's listening for the perceived loudness/distortion limit he's used to hearing when tonally balancing a typical vented woofer stack.

This I can believe. Being used to low distortion horns, folks tend to listen to them quite a bit louder than a typical cone/dome speaker. Still, in playing with mine, I seriously damaged the structural integrity of my house with a pair and some pipe organ music, but not once did I hear any of the 'doubling', power compression, etc., typical of high output subs.

Its lack of a point source's 90deg phase shift makes blending to a sealed or EBS system perfectly seamless.

====

>How will the output of a Contrabass compare with a single Tumult?

====

The CB is ~92dB eff. and I've been told it can handle 2kW for a short period of time with no compression or non-linearity down to <30Hz, so I imagine it will drown out a Tumult........ It's academic though since you can't use the CB to its limits in a typical room without doing structural damage. It only took 500W with my pair.

====

>Lastly , I am putting the Contrabass in my 8.5' x12' HT room , as I understand it I am going to have to EQ the heck out of it and buy an amplifer that can drive anything.
What is a good amp and EQ for the Contrabass?

====

It depends on what motor is in it. If it's a SD unit, then any quality amp that can handle a 2 ohm load AFAIK, but check with SD to be sure. If it has the 0.89 ohm motor that many used in their DIY units, then basically you either need an amp rated to DC, such as the old Crown DC300, or use an autoformer to impedance match to a higher resistance amp. Mine had the 0.89 ohm motors and I drove them with a well used QSC USA 900 amp till it popped. It lasted for a lot longer than I expected it to, so if they're still building them like they used to, QSC would seem a good choice.

As for EQ, I haven't kept up with what's available so don't know if there's an EQ unit that goes down to <14Hz where the CB's tuned.

Anyhoo, hope it arrives in good shape, and after you get settled in with it, let me know what you think.

GM

James W. Johnson · 01-17-2004, 10:43 AM

ServoDrive or DIY unit? New/used? If used, by whom, and for how long?
>>>>>>>>>>

Its a new , never used unit from when the company was called Intersonics. I am not sure what the whole story is but he had 4 and never used 2 of them. Me and another fellow worked out a deal on both of them.
They are unfinished birch which used to be an option...
I'll probably finish mine with Formica or something.
Mark Seaton was nice enough to do a little research on them and he thinks they are legit units.

Assuming it's in good condition, the only subs that I'm familar with that can begin to compete SQ wise is a huge basshorn or extreme IB such as TW's. I haven't seen the distortion specs or auditioned a Tumult, so can't offer any opinions on it, but I would be surprised if any point source driver can compete that's not compression loaded.

The CB OTOH has such low distortion that one guy over on HTT described it as 'overly dry'. According to Tom Danley, they normally only fail in use because the FOH engr. will keep boosting them to destruction since he's listening for the perceived loudness/distortion limit he's used to hearing when tonally balancing a typical vented woofer stack.
This I can believe. Being used to low distortion horns, folks tend to listen to them quite a bit louder than a typical cone/dome speaker. Still, in playing with mine, I seriously damaged the structural integrity of my house with a pair and some pipe organ music, but not once did I hear any of the 'doubling', power compression, etc., typical of high output subs.
Its lack of a point source's 90deg phase shift makes blending to a sealed or EBS system perfectly seamless.
>>>>>>>>>>>

That is exciting! These days SQ is way more important to me that output is, its sounds like the Contrabass will blend well with my Klipsch Reference speakers.

It depends on what motor is in it. If it's a SD unit, then any quality amp that can handle a 2 ohm load AFAIK, but check with SD to be sure. If it has the 0.89 ohm motor that many used in their DIY units, then basically you either need an amp rated to DC, such as the old Crown DC300, or use an autoformer to impedance match to a higher resistance amp. Mine had the 0.89 ohm motors and I drove them with a well used QSC USA 900 amp till it popped. It lasted for a lot longer than I expected it to, so if they're still building them like they used to, QSC would seem a good choice.
>>>>>>>>>>>>>>>>>>>>>>>>
I am not sure what motor Intersonics used in theses, but I am pretty sure the other fellow in this deal with me who spoke with Mark Seaton said they are around a 3 ohm load.

As for EQ, I haven't kept up with what's available so don't know if there's an EQ unit that goes down to <14Hz where the CB's tuned.
>>>>>>>>>>>>>>>>>>>>>>>>>

THe other guy in this deal is going to be using a Crown Microtech 1200 and a Symetrix 551E 5 band analog EQ for his
Contrabass....if he is happy with this combo I may copy him.

Meanwhile I cannot afford the amp and EQ at the moment after buying the Contrabass so I will just take it easy and use a Parasound monoblock for now, it only puts out 250watts at 4ohms. Hopefully its enough so I can at least hear what the Contrabass is all about.

Anyhoo, hope it arrives in good shape, and after you get settled in with it, let me know what you think.
>>>>>>>>>>>>>..

Thanks, I have not been this excited about getting a piece of equipment in a very long time, I hope its all I expect and then some.

Seth_L · 01-17-2004, 12:04 PM

I'm going to buck the trend and say that a PR'd Tumult in about 7-8 cu ft should equal the SPL of a single contra. However, the Tumult will take several times the power to do it.

I've heard a Contra, and my own single Tumult with PRs and the Acoustic Visions Everest (2 Tumults). They all sound very good and can play very loud.

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James W. Johnson · 01-18-2004, 10:56 AM

Greg, do you know of any websites where I can chat with other Contrabass owners? It does not seem like there are very many here or at AVS and I know there are none at HTT.

ThomasW · 01-18-2004, 12:04 PM

James

Have you tried here?
http://spl-servodrive.prosoundweb.com/

Greg Monfort · 01-18-2004, 03:59 PM

>I'm going to buck the trend and say that a PR'd Tumult in about 7-8 cu ft should equal the SPL of a single contra. However, the Tumult will take several times the power to do it.

====

Dunno, the numbers I have say it won't, but have no way to prove it. Are you implying that the Tumult is very conservatively rated and can heat sink enough power to hit its Xmax? At a glance it looks like ~4.8kW into the Tumult puts it over the top of another's claimed peak for the CB.

====

>I've heard a Contra, and my own single Tumult with PRs and the Acoustic Visions Everest (2 Tumults). They all sound very good and can play very loud.

====

Yeah, I believe all these are so extreme that it's more about SQ than peak SPL in a HIFI/HT app.. The true test for these is an outdoor prosound app.. It would be interesting to see how the Tumults fare on the CB's 'home turf', though it's understood that it wasn't designed specifically for it.

====

>Greg, do you know of any websites where I can chat with other Contrabass owners? It does not seem like there are very many here or at AVS and I know there are none at HTT.

====

There's always the basslist (DIY speakers) gang that bought the kit and the Live Audio Board or other prosound forum.

GM

Seth_L · 01-18-2004, 11:46 PM

Quote:

Dunno, the numbers I have say it won't, but have no way to prove it. Are you implying that the Tumult is very conservatively rated and can heat sink enough power to hit its Xmax? At a glance it looks like ~4.8kW into the Tumult puts it over the top of another's claimed peak for the CB.

According to the numbers on the CB I've seen 114dB @ 16Hz. My Tumult can do >114dB all the way down to about 16Hz according to the simulations. Granted it takes a lot more than 200W to do so, but it does get more SPL.

Greg Monfort · 01-19-2004, 12:51 AM

OK, you forced me to actually go look up the ratings.

114dB/16Hz is its continuous rating.

It's official peak rating is 'almost' 2 acoustic watts/16Hz/m, or 'almost' 123dB, which is beyond the Tumult's Xmax, and forget it handling the power requirements.

Someone from SD will have to explain what 'almost' means, but what I can say to a certainty is that two in my open room that measures no gain down to <16Hz pegged a calibrated SLM (>120dB) with only 500W/16Hz and literally 'brought the house down'.

Regardless of whether the Tumult can match SPLs or not, if it can reach >114dB/16Hz with any degree of SQ similar to the CB it's quite a bargain. After all, the last price I saw for the CB was $3k........

GM