Proper amp for Tumult (1 Viewer)

[Jeffrey Stanton]

Hey John:

I guess anything's possible in this case. Could be the driver. Amp could've been clipping. Or maybe BOTH scenarios occurred. Let us know what you guys find when the driver eventually gets to you and is examined.

Thanks,

Jeff Stanton

 

[Jeffrey Stanton]

Hey guys:

For all you who thought there were no pro amps available with rumble filters, can you say "Mackie 1400i"?


http://www.8thstreet.com/product.asp...wer_Amplifiers

Rumble filter adjustable from 0-170 Hz. Even has a subwoofer crossover, clip limiters, blah blah, check it out. Nice piece of work. Should be enough to make any Tumult happy.

Thanks for your inputs.

Jeff S.

 

[Jeff Meininger]

I know what a sub bottoming sounds like... I'm the proud owner of an EBS shiva in an oversized living room.

But what does an amp clipping sound like?

At times of massive excursion, an AV15 sub I helped my stepdad build for his house would start to sound "funny". It wasn't so much a single noise that could be isolated from what you were supposed to hear... the bass just got a little funny-sounding to me. Bubbly, or warbly, or something. Much more subtle sound than "bottoming out". Is that clipping? His sub (250L, 20Hz) is being powered by a PE 250W plate amp. This observation was made during the initial "wow factor" testing with the amp's gain knob at half, and the AVR's sub gain set at 0. Calibrated level has the plate amp gain at about 1/3.

But DAMN 250W can make that cone move. I was scared the thing was going to self-destruct... not so much because of the subtle noise, but because of the amazing visual impact of seeing that cone moving so far. LspCAD says that my maximum excursion would be 35mm point to point at a spot below tuning and above the rumble filter's significant control... so maybe I shouldn't have been worried since I guess I have 46mm to work with. Wow.

I ordered my own AV15 driver along with him... both of ours are early (original preorder) runs that are dual-voice-coil. His sounds really nice (particularly at normal listening levels), and I look forward to building my own. Poor driver has been sitting collecting dust for a long time now. I don't have time to build a nice box sub, so I'll probably downfire it in a sono. Shame, though, because watching that cone move is almost as much fun as watching the movie.


Brian_DR: what order rumble filter do your plate amps use? I know the PE uses a 2nd order butterworth fixed at 18Hz.

 

[Jeffrey Stanton]

Well, the Tumult arrived yesterday. Took the AV-15 out and lo and behold guess what I found? The sub was wired so that BOTH voice coils were wired to their respective posts. Well, what's wrong with this, you might ask? The Rythmic Audio amp I is not rated for 2 ohm usage, and unless I'm missing something here, the driver was supposed to be wired IN SERIES so as not to fry things by having the wrong load for the amp.

So it looks like what was happening was I had the Rythmic amp with it's 380 watts going to ONE voice coil, with a resultant 2 ohm load being presented to an amp that isn't designed to handle 2 ohm loads. Ouch.

Kyle or John, if you are out there can you give me an address to send the AV-15 in for repair? Also, my thumb went through part of the foam surround when my drill slipped, so there's a small tear in that which will need repairing also.

 

[Jeffrey Stanton]

Well I got the extra 600 gms of clay & washers added to each PR & got the Tumult wired up to the Mackie. I am sending the stereo (L,R) LFE output of the Yamaha to one channel of the Mackie, and the mono LFE to the other channel.

There's almost no sound coming from the subwoofer except some very low rumbling. Both channels are connected to the amp properly because if I raise and lower the amp gain for each channel the "rumbling" will rise and fall also.

Seems to be a problem with the amount of voltage the sub amp is getting. This is what makes NO SENSE to me: Other subs work quite well with the Yamaha's LFE. I run a Klipsch KSW-15 off it, a Yamaha YST-80, and the Rythmic Audio subwoofer plate amp. None of these had any problem with the voltage from the Yamaha's LFE. The other pro amp I had wouldn't work off the LFE either. I thought that maybe it had a built-in rumble filter that was causing the problem, so I bought the Mackie 1400i as it has an adjustable/defeatable rumble filter. Now I am encountering the same problem with the Mackie: NO subwoofing.

Does anyone have any ideas as to how to get my Tumult woofing?

 

[Brian Bunge]

Jeff,

First of all, your AV15 was not wired up incorrectly internally. Whoever assembled it, John or Kyle, wired each VC to each binding post to allow for the most flexibility in running the sub. I mentioned this in your thread in the speaker forum. By wiring each VC to each set of posts, you can run the VC's in series, parallel, or on independent channels. So the VC's weren't wired incorrectly, but rather you connected the amp incorrectly to the sub. I realize you did this unknowingly, but there'd be no reason to have dual binding posts on the back of the cabinet if the VC's were wired in series or parallel internally. It sounds like there was simply a miscommunication between you and Kyle.

Concerning the Mackie and your Tumult, I'm a bit confused as to how you have things connected. How are the VC's of the Tumult connected? How is the Tumult connected to the binding posts? To both pairs, or just one? And I'm also confused as to how you're running the Mackie. Are you running each channel to a set of binding posts? You may be shorting out the VC's.

 

[Kyle Richardson]

Yes, all dual voice coils are wired to each binding post on the input cup as to allow the variety of wiring options. I'm sorry if I didnt make that clear.

Yes, please explain how you have the Mackie hooked up. I'm not sure why you would have the stereo LR hooked up to one channel and the LFE to the other.

 

[Jeffrey Stanton]

Hi Kyle:

OOooops on the connection of the Rythmic amp to the sub. So I should've gone to the (+) on one set of posts & to the (-) on the other set? I had just gone to the +/- on only ONE set of posts...


As for the present wiring set-up:

The DSP-A1 has 3 LFE subwoofer outputs: a "left", a "right", and a "MONO". I used all three to try to get more voltage to the Mackie...I sent the "MONO" LFE to one channel and used a y-splitter to sum the "left" and "right" LFEs to the other channel of the Mackie. I also have each VC of the Tumult connected the same way the AV-15 was wired. All I'm getting is a hum and some faint, diffuse sort of bass response. What gets me is why other subwoofer amps will work but as soon as I put a pro amplifier into the mix I get nada.

I had talked with someone else on this forum who is using the same Mackie 1400i amp to run a couple SVSs with his Denon A/V receiver and has no problem with it. I might add that the first pro amp I used (with the same subwoofer results) works just fine as a regular stereo amplifier. What in the heck do you think is going on here?? :frowning:


Jeff S.

 

[Brian Bunge]

So I should've gone to the (+) on one set of posts & to the (-) on the other set?

Plus the jumper from the other + to the other - posts like I mentioned for series wiring.

 

[Jeffrey Stanton]

Here's some technical specs FOR THE A/V amp and the SUBWOOFER amp which may or may not help to determine why the Tumult is making no bass as of yet:

OUTPUT LEVEL/IMPEDANCE for Yamaha DSP-A1:

SUBWOOFER (SPLIT L,R) (EFFECT OFF)...1.2V/1.2kOhm

SUBWOOFER (MONO) (EFFECT OFF)........2V/1.2kOhm



And for the Mackie pro amp:

INPUT IMPEDANCE................20 kOhm
INPUT SENSITIVITY...1.23 volts (+4dBu) for rated power into 4 ohms
MAXIMUM INPUT LEVEL........9.75 volts

Any obvious mismatches here? Seem to me that for the input sensitivity of the Mackie (1.23 v) is matched OK with the output of the LFEs from the Yamaha (1.2 v and 2 volts).

But what about the impedance of each? The Yamaha has 1.2 kOhms impedance while the Mackie has a 20 kOhm impedance rating. What does this mean?

Any help would be greatly appreciated. I've spent close to $2000 on this project which started last October, and I'll I've got to show for it is a shattered AV-15 and a brand new Tumult in a great enclosure that just sits there and hums at me.

Surely SOMEBODY out there has some idea of what is going on here...if not, can any one suggest somebody I could talk to who might be able to help me get this thing off the ground?

C'mon, somebody throw me a bone on this one.. Would offering a reward of some sort help or should I start another thread (maybe this one's gone on too long) or maybe just seek assistance from a qualified professional?

Thanks,

Jeff Stanton

 

[Jeffrey Stanton]

Can anybody take a look at the above post and see if there's poosibly a voltage/impedance mismatch between my LFE and the Mackie amp?

Thanks,

J Stanton

 

[Craig Woodhall]

buddy, i was running a Mackie FR-1400 to a variety of subs, and it worked flawlessly. imo, you are wiring it up wrong somewhere down the line.

If i were you, forget the 3 sub outs. run the mono subwoofer output to one input on the back of the Mackie. wire the Tumult in series for a 4ohm load and then bridge the mackie and run it to the Tumult.

Craig

 

[Jeffrey Stanton]

The answer appears to be "none of the above". I undid everything, & hooked up the sub again EXCEPT I used a Pioneer C-60 pre-amp in conjunction with the Mackie. This time it worked. The number of sub inputs I tried to use has absolutely nothing to do with it.

Maybe someone can explain why my sub/amp needs a pre-amp and evidently no one else's around here does.

Thanks for your response Craig

 

[Dan Hine]

Pro gear typically needs a higher input voltage than home audio gear puts out. You need a preamp to boost the signal from your Yamaha. Also, I'm assuming that you have the gain knobs on the Mackie turned all the way up. If not, you should.

- Dan

 

[Jeffrey Stanton]

Thanks Dan:

The gains on the Mackie are turned up all the way, and the volume control on the Pioneer pre-amp needs to be 3/4 to ALL the way up (or somewhere in-between) to get the little red lights on the Mackie to come on occasionally...

 

[Dan Hine]

Hmm...you don't really want your red lights to come on. Unless it's just a flicker during a very bass heavy scene. Anyhow, with the preamp in place are you getting bass response you're pleased with or are you still having troubles?

 

[Jeffrey Stanton]

Hey Dan:

I've been adjusting the frequency of the flashing of the red lights with the volume control of the pre-amp so that they only flash occasionally with music and with heavy bass scenes, like you indicate. I know that they're clip indicators so you do not want them "on" all the time...I guess the question is where exactly do I draw the line as to their frequency.

With the pre-amp in place I was a little surprised at having to have the volume control up to 3/4 or even as high as all the way up (depending on the source).

But the response is quite adequate, using the performance of the AV-15 with the Rythmic Audio as a reference (which I was using before the Tumult). Like Kyle Richardson told me, it isn't a night and day difference, but the SPL is a bit greater with the Tumult, and I had added 600 gms to each of the PRs so the Tumult sounds a little different(lower).

As it turns out it looks like I was running the previous driver (the AV-15) as a 2-ohm load with the Rythmic amp because there was no jumper connected to the inputs. I think I was probably sending the AV-15 a lot more than the 380 watts I thought I was (Brian Ding, are you out there to comment on this)?

Jeff S.

 

[JesseSilver]

>>As it turns out it looks like I was running the
>>previous driver (the AV-15) as a 2-ohm load with
>>the Rythmic amp because there was no jumper
>>connected to the inputs. I think I was probably
>>sending the AV-15 a lot more than the 380 watts
>>I thought I was

I'm not Brian, but I'll offer my thoughts. I received an AV12 last week that I briefly tested with my multimeter. It's a Fluke 87III, so it's really accurate and I completely trust it's measurements. The AV12 I tested (which shares the motor assembly with the AV15) had a DC resistance of about 1.6 ohms across each of it's two voice coils. This is even less than the 2 ohms it's supposed to be, but not a problem if properly hooked up in series to yield a bit over 3 ohms. You were pushing that 380 watt (at 4 ohms) into less than two ohms, so the wattage could have easily gone to 700+ watts, and frankly I'm a bit surprised you didn't ruin the amp as well. The fact that you ruined the driver isn't a big surprise. You were pushing those 700+ amps through only ONE of the voice coils, so assuming each has the ability to dissipate a certain amount of power as heat, you had half as much heat dissipation capability as you normally would have. In series, all circuits have the same current, so your current wasn't higher than it would have been, except the wattage probably doubled, so I'm not sure what effect that had on the current.

Summary? I seriously seriously doubt you would have had any problem running that AV15 with the rythmik amp if it had ben properly wired. Plus, it would have sounded awesome, whereas you only had one magnet hooked up so it was as if Stryke had designed the AV15 with half as thick a magnet and half as long an active voice coil! Not good for sound...

I really hope people read this whole thread because anyone stopping on the first post will get a very negative impression of Rythmik and possibly Stryke, neither of which is at all warranted (in my opinion)

Oh, and with regards to the Mackie... are you at all familiar with -10/+4 ? Pro and consumer gear output and expect input at very different levels, much to the dismay of people who try to mix pieces together. I suspect you are one such person, as your Mackie probably expects inputs at +4, and your sub output is probably at -10. The 14 db difference is easily audible (as 10 db sounds, more or less, like half the volume), so the preamp is necessary to make up for this level difference. This is just a guess, though... I have a lot of recording studio experience, but it's been a while

 

[Brian-K-Owens]

"had a DC resistance of about 1.6 ohms across each of it's two voice coils. This is even less than the 2 ohms it's supposed to be, but not a problem if properly hooked up in series to yield a bit over 3 ohms."

DC resistance of the coil is less than the impedance of the coil. When you send an AC signal through the sub, the impedance will change with frequency.


I could not tell you if that amp can actually double its power at 2 ohms. I am not trying to sound negative about the amp; I have never used it, but if it can double its power at 2 ohms, then there would be a good chance the mininum impedance rating would be less than 4 ohms, so I doubt he was actually driving the sub with 700+ watts. I could be wrong. . . .


I have never met Jeffery, but I am the reason he began to raise such big concerns over the AV-15 sub. I feel strongly that he has a valid agruement as to his driver failure, and I told him so in an email, as what I had to say I did not want to spread all over a public forum. I will also say that I am not being negative about the AV-15; it is a GREAT driver, and I will continue to buy them in the future, but in his case it is possible that the driver failure was not his fault. . .even if he did not connect it properly.

Brian

 

[Jeffrey Stanton]

Just a little "heads-up" for Stryke/Acoustic Visions re: instuctions for hooking up an AV-15 sub. It would have helped a lot and in fact may have averted this whole mess if they (someone) would have included a note or something with the shipped sub with some brief instructions as to how to hook the driver to a given amp.

In all fairness, I do recall John J. briefly going over some wiring instructions with me on the phone one morning. When I finally did get the sub some weeks later, but not having a xerox copier for a brain, I must have forgotten the "jumper" part. And I could not see inside the sub to see how it was wired. As there was no jumper or instructions included, the first thing I tried (as I recall) was to connect one driver lead to the (+) on set of posts and the other lead to the (-) post of the other set. As I got nothing from that, I tried the (+) and (-) of ONE set of posts and got PHENOMENAL bass output. For a couple of weeks, anyway, then things started going sour after a couple of DD/DTS heavy bass scenes.

That AV-15 is right up there with the Tumult in performance, no matter how I had it wired. For the price, it wins handsdown in the bang/$ competition.

And the Rythmic amp performed extraordinarily well considering what was being asked of it!! Yow.

But the whole point of this is that some brief WRITTEN instructions would have done a world.

Sorry for any misunderstandings,

Jeffrey S.