quote:Originally posted by Meyer: Well, the reason for such a small gain is because the amplifiers efficiency is drastically reduced. The amplifiers are not being used as they were designed. I am not sure if you know this, but when you strap 2 Bd1501's together, their effeciency drops to 25%; and these amps are designed to do this. Just think of what happens to an amplifiers effeciency when not being used properly. Another reason, is that you lose a lot of energy to heat. Essentually, energy is power, so you can't afford to lose too much of it. I will try to get more detailed information, but I am sure thiguys tests were legit as one of my good friends was a witness to them.
So, when it comes to competing in the lanes, if you want to strap say 8 Mojo's on 4 coils----more power to ya. Just don't be surprised if someone w/ 4 Mojo's beats you. Like I said before, it can be done but the results were far less then satisfactory.
Later,
Jason Meyer
Just curious, but where did you get this information from? I would really love to talk to whoever did these tests, and ask them specifically what they did, and how they measured results. As far as the 25% efficency goes on a BD 1501, I think I would need some more evidince before I believe that (not saying its not necessarily true).
The brand of amps that I am most familiar with is crossfire, and have done by far the most amount of testing with them, so I will use them as an example.
When you take two VR1000ds and you "strap" them... you are doing essentially just what we are talking about, running the outputs in series. In all of my tests I have no evidence that would lead me to believe that the efficency drops at all, much less to 25%. Also, when you strap these amps, the voltage IS doubled.
The only other thing I have to say for now is that you guys are forgetting just one thing. I have ALREADY done this... with very excellent results (with the 202s, as explained before) Voltage DID double, and the amps performed nearly flawlessly. As I said, more tests will be underway soon, and I will inform you of the results.
Is there anyone else out there thats reading this, that has FIRSTHAND experience and results trying a setup like this? (not a friend of a frind...) I'm very eager to hear your results and some specific data
As I stated before, I will be conducting more tests very soon, and will let you all know of the reult, either good or bad
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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posted
Also, I plan on taking some pictures, however I do not have access to any ftp server to upload them to. Would anyone be able to help me out and store some pictures for me on the web for a little while? Thanks in advance.
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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posted
The 25% is accurate on both Rockford amps and crossfire amps. The information about the Bd1501's came from the Riley's and Rockford. The information about the crossfires came directly from Casey at crossfire(which I believe he doesn't work there anymore).
Example: A VR1000d is capable of producing 2200 watts peak. A pair of VR1000d's strapped are capable of producing 3200 watts peak. Remember, these amps are designed to do this. Thus, it is common sense that tells an amp won't perform very well when wiring it differently then how it was designed to be wired.
I have had plenty of experience w/ crossfire and I love their amps. In fact I will be running them this year, but I really don't see these amps or any subs being able to handle what you are trying to do. I think the only results you will get when you try to do this w/ large amps is a lot of distortion+ extreme heat= blown amps and/or blown coils.
Later,
Jason Meyer
-------------------- 2004 SS 1-2NW World Champion 2005 World Finals SS 1-2NW 2nd Place 2006 World Finals SS 1-2NW 3rd Place Team Maxxsonics Member of Broken Silence Competition Team Posts: 194 | From: Sedalia, MO, USA | Registered: Aug 2000
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-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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posted
I don't get it. Why are you so intent on using optocouplers when a simple transformer will isolate the inputs and keep the signal intact? After all, a transformer secondary is essentially a floating ac voltage source.
Posts: 768 | From: Ottawa, On, Canada | Registered: May 2000
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quote:Originally posted by netlohcs: Also, I plan on taking some pictures, however I do not have access to any ftp server to upload them to. Would anyone be able to help me out and store some pictures for me on the web for a little while? Thanks in advance.
quote:Originally posted by Meyer: The 25% is accurate on both Rockford amps and crossfire amps. The information about the Bd1501's came from the Riley's and Rockford. The information about the crossfires came directly from Casey at crossfire(which I believe he doesn't work there anymore).
Example: A VR1000d is capable of producing 2200 watts peak. A pair of VR1000d's strapped are capable of producing 3200 watts peak. Remember, these amps are designed to do this. Thus, it is common sense that tells an amp won't perform very well when wiring it differently then how it was designed to be wired.
I have had plenty of experience w/ crossfire and I love their amps. In fact I will be running them this year, but I really don't see these amps or any subs being able to handle what you are trying to do. I think the only results you will get when you try to do this w/ large amps is a lot of distortion+ extreme heat= blown amps and/or blown coils.
Later,
Jason Meyer
My MTX 1501d's do around 2100 individually and do a little more than 4200 strapped...
-------------------- Scottie Johnson Sound Pressure Technologies
quote:Originally posted by Meyer: The 25% is accurate on both Rockford amps and crossfire amps. The information about the Bd1501's came from the Riley's and Rockford. The information about the crossfires came directly from Casey at crossfire(which I believe he doesn't work there anymore).
Example: A VR1000d is capable of producing 2200 watts peak. A pair of VR1000d's strapped are capable of producing 3200 watts peak. Remember, these amps are designed to do this. Thus, it is common sense that tells an amp won't perform very well when wiring it differently then how it was designed to be wired.
I have had plenty of experience w/ crossfire and I love their amps. In fact I will be running them this year, but I really don't see these amps or any subs being able to handle what you are trying to do. I think the only results you will get when you try to do this w/ large amps is a lot of distortion+ extreme heat= blown amps and/or blown coils.
Later,
Jason Meyer
My MTX 1501d's do around 2100 individually and do a little more than 4200 strapped...
ditto
-------------------- 2005 Florida Street C Champion 2004 SBN Street C Champion 2004 SBN IDBL No Wall Champion 2003 NOPI Nats Street B Champion
How did you measure the output when standing alone and when strapped?
If all you are going off of is ac voltage, that won't always be a true reading of power. I am just asking because a lot of people just read voltage then plug that # into a formula and bam my amp is doing X watts. Also, when you strap amps, a lot of previous givens change.
I would like to know, because I get approx. 3800 watts out of each X7 that I have.
Later,
Jason Meyer
-------------------- 2004 SS 1-2NW World Champion 2005 World Finals SS 1-2NW 2nd Place 2006 World Finals SS 1-2NW 3rd Place Team Maxxsonics Member of Broken Silence Competition Team Posts: 194 | From: Sedalia, MO, USA | Registered: Aug 2000
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posted
I'm guessing Scottie's got an amp clamp. He does have everything else you could need for testing a sound system. FYI, I believe he's running 9 Brahma 15s with 2 strapped pair of the MTX amps (over 8000 watts) per sub. May be wrong, but it's something along those lines.
posted
Why not run a seperate charging system for the head unit? So say you have two seperate charging systems. First is the amp system. Second is the signal system. Mount the alternator with a non-conductive material, then ground system #2 directly to the alternator case. Rubber mount the h/u and ground it directly to alternator case. Then you should have no contact between signal - and amp -. I might have missed something, but hopefully you see what I'm seeing in my head.
-------------------- Hello, my name is Danny and I am addicted to slurpies. Hey, wanna check out my sounddomain site? http://members.sounddomain.com/tocooldrw2 Posts: 425 | From: Port Orchard Wa | Registered: Jun 2003
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posted
The way RCA cables work is that the signal is carried on one wire, which corresponds to the center pin part of the plug, and that signal is referenced to the other wire/shielding/whatever that is the outside shield part of the plug. That shield is referenced to ground. There has been talk in this thread about signal isolation because the amps' batteries will be at different potentials, therefore the signals' ground references will be at different potentials. Giving the HU it's own charging system won't help this at all, and in fact, I believe that during netlohc's testing, the HU essentially had it's own charging system because the amps were powered by batteries that were not connected to the primary electrical system of the vehicle.
-------------------- Hello, my name is Danny and I am addicted to slurpies. Hey, wanna check out my sounddomain site? http://members.sounddomain.com/tocooldrw2 Posts: 425 | From: Port Orchard Wa | Registered: Jun 2003
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posted
Ok, so I hardly ever get on here any more so this may be my only post on this subject....
Sounds like you are onto something, but it seems like way to much work.....
So here is the easy solution:
STEP 1. Take your normal mono block amps, strap them together and you double the power
I am concerned with people saying that the crossfire developed less then double the power when strapped together....
in my testing experience using the AP the only way this is possible is if your power supply is not capable of supplying double the current
A test that shows results like they are talking about is usually done with batteries or a weak power supply. Remember that amps of this size are drawing 200 amps of current+ and maintaining 14v-18v with 200 (one amplifier) to 400 amps (2 amplifiers) of current requires an investment of at least $10,000 for a decent power supply that runs off of 480v A/C (ohh yea that was for a used one!!)
Once I had access to this kind of power supply my testing was way more accurate.....
On to the good news and the easy way to strap 4, 6, or 8 amplifiers onto a single voice coil!!!!!!
STEP 2: Take a second "pair" of "strapped amplifiers" and parallel them to the voice coil.....
Now you are saying "ok no increase in power".....
Well, you are correct, but what we have now gained is an amplifier (actually 4 of them) that is capable of twice the current....
Now to get more power take away your 2ohm voice coil and replace it with a 1 ohm voice coil.....
and you have doubled your power.....
Or even better, add another pair or two and try a half ohm coil.......
what I ended up with was 8 (we will call them "brand xyz") amplifiers playing burps into 36 refrigerated (yes I put them in the fridge!!!) .5 ohm resistors @ a bit over 15,000 watts
Even this taxed the power supply and should have been closer to 18,000 watts @ 18 volts......
So the answer is yes it can be done (no blaming me for blown up amplifiers trying, as I blew up more then a few...)
As for reliability... IT IS NOT GREAT...... Could you make it through 1 competition?... Probably...
Can you find some .25 ohm quad coils? ... Probably not......
My only concerns with this are phasing problems and the fact that when one amp goes down it usually takes at least 4 of them with it...
Hope this helps, and like I said, I hardly have time to get on here anymore so I will check back in a few weeks and see what else you crazies have come up with!
Thank you for your time, and some fun posts about the future of car audio
Gary Bell
(ohh yea and the easy solution is just building bigger amplifiers, it is in the works and the only real problem is getting someone to pay the bigger money for them!)
-------------------- Member of Team XS-SPL --------------------- Posts: 242 | From: Tustin , Ca USA | Registered: Dec 2000
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posted
Strapping is a funny marketing term. I still rather call it "bridging the bridged amplifiers".
This technique will work if you know how to do it. It's for the electronics saavy person who knows what is going on.
To get a better grasp, start with the ideal situation and work backwards.
1. Same amplifiers.
2. isolated +12v batteries from each amp.
3. isolated input signals (use an audio isolation transformer).
4. the amplifier DC-DC converter output ground is isolated from the power input ground (chassis ground).
Paralleling amplifiers to increase current is another interesting project -- if you have some very low impedance woofers, lets say 1/8 ohm impedance parallel four 1/2 ohm stable same brand amplifiers with matched gains.
I'd rather buy that new JBL/Crown 10kw? amp that is coming soon, 1000 ampere draw? /hehe
Post pics when you are done bridging the bridged amps Posts: 47 | From: California | Registered: Feb 2003
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quote:Originally posted by Nomad84: I'm guessing Scottie's got an amp clamp. He does have everything else you could need for testing a sound system. FYI, I believe he's running 9 Brahma 15s with 2 strapped pair of the MTX amps (over 8000 watts) per sub. May be wrong, but it's something along those lines.
Your guess is correct... sorry I don't have any prizes at this time
-------------------- Scottie Johnson Sound Pressure Technologies
quote:Originally posted by Meyer: Question to those with the MTX 1501's----
How did you measure the output when standing alone and when strapped?
If all you are going off of is ac voltage, that won't always be a true reading of power. I am just asking because a lot of people just read voltage then plug that # into a formula and bam my amp is doing X watts. Also, when you strap amps, a lot of previous givens change.
I would like to know, because I get approx. 3800 watts out of each X7 that I have.
Later,
Jason Meyer
Measurement with a high end fluke DMM set on Vac and a fluke clamp meter so we are dealing with RMS values. Multiplying those two values gives RMS power.
As an example each of my mtx 2300x's, when run into a DCR impeadance of 4ohm, are rated to do 600 per MTX. Playing 38hz in my long ago nowall install had them doing 748 watts each by multiplying rms power with rms current.
Output per amp (mtx 81000d) does not change in my case weather strapped or individually set up. Each amp given the same impeadance in both setups. Severe voltage drop to 10.7 or so. When it was maintained at a higher voltage the amps went crazy making power.
-------------------- 2005 Florida Street C Champion 2004 SBN Street C Champion 2004 SBN IDBL No Wall Champion 2003 NOPI Nats Street B Champion
quote:Originally posted by Nomad84: I'm guessing Scottie's got an amp clamp. He does have everything else you could need for testing a sound system. FYI, I believe he's running 9 Brahma 15s with 2 strapped pair of the MTX amps (over 8000 watts) per sub. May be wrong, but it's something along those lines.
Your guess is correct... sorry I don't have any prizes at this time
You've got Vipers..and Yellowtops... I'd settle for either
posted
I haven't posted on this topic in a while, i have been too darn busy with the shop I have some "larger" amps on the way though however, and plan on doing some more testing very soon... so stay tuned, I will let you all know how it turns out.
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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posted
OK, our team did some REAL WORLD TESTING in a real dBdrag car!!! We did not refrigerate our resistors becuase we used REAL AMPS in a REAL dB drag vehicle!
we tried strapping 2-2000 watt class d's brand -x they are not strappable from the factory but the factory said we could do it simply and we followed their EXACT directions. they held at low to medium short burps BUT when we tried to get a gain over what we had then FIRE occured!!! the factory said it works perfect on our test bench!!! with resistors on our power supply and it should work in your setup, BUT as everyone in dBdrag knows a TEST BENCH AND RESISTORS NEVER IMMULATE real world application!!
-------------------- S.W.A.T. TEAM KINETIK TEAM OHIO GENERATOR T3 AUDIO TEAM BUDWIESER Posts: 3656 | From: Omaha, NE | Registered: Oct 1999
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quote:Originally posted by TRENDSETTER: OK, our team did some REAL WORLD TESTING in a real dBdrag car!!! We did not refrigerate our resistors becuase we used REAL AMPS in a REAL dB drag vehicle!
we tried strapping 2-2000 watt class d's brand -x they are not strappable from the factory but the factory said we could do it simply and we followed their EXACT directions. they held at low to medium short burps BUT when we tried to get a gain over what we had then FIRE occured!!! the factory said it works perfect on our test bench!!! with resistors on our power supply and it should work in your setup, BUT as everyone in dBdrag knows a TEST BENCH AND RESISTORS NEVER IMMULATE real world application!!
Hmmmm very interesting What brand amps did you use out of curiosity? And, if you dont want to divulge that information, could you possibly at least tell us what their exact instructions were? I would be very curious to know....
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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quote:Originally posted by TRENDSETTER: OK, our team did some REAL WORLD TESTING in a real dBdrag car!!! We did not refrigerate our resistors becuase we used REAL AMPS in a REAL dB drag vehicle!
we tried strapping 2-2000 watt class d's brand -x they are not strappable from the factory but the factory said we could do it simply and we followed their EXACT directions. they held at low to medium short burps BUT when we tried to get a gain over what we had then FIRE occured!!! the factory said it works perfect on our test bench!!! with resistors on our power supply and it should work in your setup, BUT as everyone in dBdrag knows a TEST BENCH AND RESISTORS NEVER IMMULATE real world application!!
quote:Originally posted by TRENDSETTER: OK, our team did some REAL WORLD TESTING in a real dBdrag car!!! We did not refrigerate our resistors becuase we used REAL AMPS in a REAL dB drag vehicle!
we tried strapping 2-2000 watt class d's brand -x they are not strappable from the factory but the factory said we could do it simply and we followed their EXACT directions. they held at low to medium short burps BUT when we tried to get a gain over what we had then FIRE occured!!! the factory said it works perfect on our test bench!!! with resistors on our power supply and it should work in your setup, BUT as everyone in dBdrag knows a TEST BENCH AND RESISTORS NEVER IMMULATE real world application!!
Looks like they got it to work.
Lat NeillBarber
What amps were they using at SBN? Anybody know??
-------------------- Nate Scholten Team Sounds And Motion SS 1-2 3rd place 2004 finals -THE BUILD- ~Our Drinking Team Has A Stereo Problem~ Posts: 4253 | From: Rhinelander,WI | Registered: Dec 1999
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