file Needing to be as sure as possible !!!

5 years 2 weeks ago - 5 years 2 weeks ago #21883 by bjm362
I have used some amps with bridge mode before, just none that did not come with the correct circuitry. I have read numerous conversations on how this can be done and what the risks are. However since even if this is done theoretically correct, it still has potential for disaster I want to be as certain as I can. I want to bridge an amplifier not set up for bridge mode operation. Please fill in any blanks and correct any errors as best as possible. going through the audio chain in order. Item one, mono signal source. Item two signal splitter/ y adapter. item 3 dual line attenuator with exact same add/ reduction on both channels ( the attenuator serves three purposes. to provide + signal to two places and to prevent the split signal from clipping due to impedance drop as well as assure the signal adjustments are the same on both leads.)Next I need an inexpensive device to reverse the phase on one lead. Next connect the normal positive lead to amp channel A and the phase reversed lead to channel B. Connect the positive lead from driver to positive connection on channel A, and the negative lead on the driver to the positive connection on amp channel B. connect power cables with all switches off and all forms of level/ attenuation all the way down. Power on signal source. power on amp last. begin adding signal in small incremental adjustments.
If I have that part correct, I have all the parts except the inexpensive phase reversal device. I also am not certain if this method is the one where you only use the gain on channel A or not.
Most of the parts specific models are not relevant to the test, but the amp model could be. The amp in question is not a great amp, If this works however this should in theory make it very useful to me. It is a Technical Pro Torque Audio AW1. It is supposed to be 2 ohm stable, but I have no intention of connecting a 4 ohm load to it in bridge mode. If this works I intend to connect an 8 ohm driver rated at 800 watts continuous and 1600 watts peak. With a rating of 360 watts rms per channel at 4 ohms, this bridge configuration should net 720 watts rms or 1018.8 watts peak into an 8 ohm load. Any help would be appreciated.

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5 years 2 weeks ago - 5 years 2 weeks ago #21905 by bjm362
Replied by bjm362 on topic Needing to be as sure as possible !!!
SOMEONE PLEASE AT LEAST ATTEMPT TO HELP!!!
I know that was a lengthy post, but I wanted to be detailed to be sure anyone who read understood that I have researched this including here. There is a small part of this I am not quite able to put together and really would appreciate any help.

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5 years 2 weeks ago #21906 by mini-mad
Replied by mini-mad on topic Needing to be as sure as possible !!!
dont piss around trying to bridge an amp that wasnt designed to... in theory yes, it would work but it wont be stable and your better off sticking both gains on both channels of the amp on as high as they will both go or solder in a "stereo" gain pot to channel A so both are turn at the same time to create a near perfect balace between the channels and it MAY work "ok".... but for what the driver is worth your plugging it into.... buy a better amp!
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5 years 2 weeks ago #21907 by mini-mad
Replied by mini-mad on topic Needing to be as sure as possible !!!
....and dont be so damned rude!!!! no one is EVER likely to help you with that fuukin' atitude!!!
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5 years 2 weeks ago - 5 years 2 weeks ago #21908 by audiomik
Replied by audiomik on topic Needing to be as sure as possible !!!
You don't need attenuators to run an Amplifier in bridge mode, a simple reversed phase input - usually channel 2 - by suitably wiring a 'Y' lead to one channel will work, by swapping connections to pins 2 and 3 in the Ch 2 input XLR.
However in order to balance both amplifier channels properly, have both level controls set at maximum.

Use your mono signal source to control level or add an additional single, good quality, balanced line attenuator at the output of your signal source which feeds your amplifier.

Output then is between '+' on the output of channel one 'Hot' and '-' on the output of channel two 'Hot' connections.

Try this into a 6 Ohm dummy load of adequate power rating, with a 'Scope and AC Voltmeter first to ensure that the Amplifier is suitable for what you are trying to achieve

Hope this assists
Mik
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5 years 2 weeks ago - 5 years 2 weeks ago #21910 by bjm362
Replied by bjm362 on topic Needing to be as sure as possible !!!
First off thank you for your reply. I actually had lost track of this site and long missed the value of experience and engineering expertise available here. If and can break down a few parts of your response we may even get further.
You certainly have a valid point in that If I were able to purchase the amps I want I wouldn't need to try this experiment which has a high risk level. however there are some counterpoints that may be of interest in this conversation. 1) My back is injured and I am just into 2 years in recovering from what I thought would only keep me down a few days. The chances of me being able to make that kind of purchase in the near future are extremely grim!
"

"dont piss around trying to bridge an amp that wasnt designed to"

Amplifiers in and of themselves are not inherently designed to be bridged, there are amps that were manufactured with the additional circuitry required to accomplish that in a stable and effective manner. The unstable attempts to do that normally are the result of a part of that circuitry being connected improperly, not being properly accounted for or left out entirely. I am attempting to emulate that circuitry externally as best as I can and requested advice due to the lack of clarity in most of the posts I have found on this topic. I chose this forum as a place to request that information because I do have a great deal of respect for the membership here!

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5 years 2 weeks ago - 5 years 2 weeks ago #21911 by bjm362
Replied by bjm362 on topic Needing to be as sure as possible !!!

mini-mad wrote: ....and dont be so damned rude!!!! no one is EVER likely to help you with that fuukin' atitude!!!

As best as I can tell there is nothing in either of my posts that could be construed as rude. However since posts in text do not totally transcribe attitude it is possible there was something I missed . If so, I humbly apologize. I certainly did not have any intent of offending anyone, nor do I expect that I will have.
The two things I can see from that that might have come across as rude are that I started with a long post in an effort to provide thorough information, then when I didn't get any response after 3 days and 10 hours I became a bit ancy and asked in a shorter post for someone to attempt to help. I don't see that as rude, but again if it came across that way I apologize!

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5 years 2 weeks ago #21912 by bjm362
Replied by bjm362 on topic Needing to be as sure as possible !!!

audiomik wrote: You don't need attenuators to run an Amplifier in bridge mode, a simple reversed phase input - usually channel 2 - by suitably wiring a 'Y' lead to one channel will work, by swapping connections to pins 2 and 3 in the Ch 2 input XLR.
However in order to balance both amplifier channels properly, have both level controls set at maximum.

Use your mono signal source to control level or add an additional single, good quality, balanced line attenuator at the output of your signal source which feeds your amplifier.

Output then is between '+' on the output of channel one 'Hot' and '-' on the output of channel two 'Hot' connections.

Try this into a 6 Ohm dummy load of adequate power rating, with a 'Scope and AC Voltmeter first to ensure that the Amplifier is suitable for what you are trying to achieve

Hope this assists
Mik

This certainly assists to say the least! There are a number of useful points in that reply that helped clarify things for me. I have some more comments to add to that, but my puppy is demanding my attention right now.

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5 years 2 weeks ago #21913 by mini-mad
Replied by mini-mad on topic Needing to be as sure as possible !!!
The idea of switch the cables within a "Y" lead is not a good one if its a cheap amp that dieant have balanced line in as you WILL need a box to inverse the phase if its unbalanced or your just be feeding channel B the ground cable and it wont work.

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5 years 2 weeks ago #21914 by audiomik
Replied by audiomik on topic Needing to be as sure as possible !!!
the Amplifier inputs aren't the critical ones, so long as there is a bi-phase source!

Mik
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