Phase shifts from using full range bridged amps?

Last night a well known car audio guy said:


“You do not want to bridge two channels into one mono channel for broadband use, there are multiple phase shifts through the bandwidth. You don’t have this issue when bridging an amp for sub use when your bandwidth is set the less than 100 hz. When using amp amp in bridged (mono) for bandwidths that cover broader ranges you will encounter phase shifts between the two channels at certain frequencies. This tends to destabilize image and stage as the phase changes.


You will be having phase shifts, it happens in ALL 2 channel amps when bridged to mono use over broad frequency ranges. It’s the inter-reaction between the two channels.”


I am neither agreeing nor disagreeing with him because in my +35 years of being an amateur car stereo guy this is the first time that I have ever heard that.


To put this in context the discussion was about using bridged (or monoblock) full range amplifiers on door speakers. So I wanted to see if anyone has anymore information on Phase shifts from using full range bridged amps?

I've never heard that either and had bridged an A/B 4ch amp for >80Hz range for years. But I didn't RTA at the time so would never have known if it did cause anything.

I think he means don't run a stereo signal to an amp that's been bridged, the two channels will want to fight each other. A single channel amp needs to see a mono signal.

seems like the statement needs more context

I've never heard of this, and don't see how it is possible. If it was, then running amps in stereo would have phase shifts too between the channels, and it would still screw up the stereo image.

The comments are from Sound Quality Competitors

https://www.facebook.com/groups/sqco...omment_mention

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Originally Posted by BigAl205

I think he means don't run a stereo signal to an amp that's been bridged, the two channels will want to fight each other. A single channel amp needs to see a mono signal.

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This seems to be the most accurate explanation. Back in the day (only because I don't see it much anymore), several amps had a Stereo/Mono switch. When switched to Mono, both channels would be driven from a single RCA input. I'm not sure how you'd get phase shift with a single input.

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Originally Posted by BigAl205

I think he means don't run a stereo signal to an amp that's been bridged, the two channels will want to fight each other. A single channel amp needs to see a mono signal.

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That makes more sense. But then why would you ever merge a L and R signal for a single speaker playing high frequencies. But I guess people could make that mistake. But wouldn't most amps just ignore the other input anyway because it's only taking the one input it identifies for bridged?

Never heard that one before.
I'm also kinda doubtful.

If the phase between channels was bad enough to be heard in bridged mode, then it should also be audible if you use those two channels in a stereo pair right?

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Originally Posted by Justin Zazzi

Never heard that one before.
I'm also kinda doubtful.

If the phase between channels was bad enough to be heard in bridged mode, then it should also be audible if you use those two channels in a stereo pair right?

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I am a responder on that Facebook post, the guy who made the statement is an ex phase linear tech

i did respond by stating I have never measured any difference in phase (which would effect timing also) between a stereo channel and then when I bridged the same amp onto the mids also, so I stated I didn’t see how it could be an issue

he wasn’t talking about a stereo input, he specifically was saying it in response to someone who wanted to bridge an amp to run various drivers (not subs)

I got told I didn’t know who he was or words to that effect, I replied with when I’ve done exactly this I have never seen any difference in phase at the speakers actual output when measured at the listening position

he does definitely know his onions and has pedigree, but I dismissed it as a none entity

as in theory at least if one pair of channels induces some kind of phase shift then the other pair of channels would, and so the phase would still match if anything changed at all

i understand that when bridging the phase is inverted on one channel of a pair to be bridged as it’s driven from the negative vs the first channels positive so when combined there is a push pull effect occurring, but that won’t effect the phase of the output as it just makes a bigger sine wave with twice the voltage effectively

curious as to what he’s speaking about… but I haven’t measured it in any case where I’ve been using stereo channels and then swapped to bridged channels and I do like measuring phase :)

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Originally Posted by Justin Zazzi

Never heard that one before.
I'm also kinda doubtful.

If the phase between channels was bad enough to be heard in bridged mode, then it should also be audible if you use those two channels in a stereo pair right?

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This was my thought, the two channels are outputting the same phase so that when bridged you get twice the voltage, if not you wouldn’t and imaging would suck between two channels and ta would be a nightmare!

as I say above he is a very well known engineer of amps who worked at phase linear, so who knows

Maybe they should have named the company Phase Nonlinear

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Originally Posted by dumdum

I am a responder on that Facebook post, the guy who made the statement is an ex phase linear tech

i did respond by stating I have never measured any difference in phase (which would effect timing also) between a stereo channel and then when I bridged the same amp onto the mids also, so I stated I didn’t see how it could be an issue

he wasn’t talking about a stereo input, he specifically was saying it in response to someone who wanted to bridge an amp to run various drivers (not subs)

I got told I didn’t know who he was or words to that effect, I replied with when I’ve done exactly this I have never seen any difference in phase at the speakers actual output when measured at the listening position

he does definitely know his onions and has pedigree, but I dismissed it as a none entity

as in theory at least if one pair of channels induces some kind of phase shift then the other pair of channels would, and so the phase would still match if anything changed at all

i understand that when bridging the phase is inverted on one channel of a pair to be bridged as it’s driven from the negative vs the first channels positive so when combined there is a push pull effect occurring, but that won’t effect the phase of the output as it just makes a bigger sine wave with twice the voltage effectively

curious as to what he’s speaking about… but I haven’t measured it in any case where I’ve been using stereo channels and then swapped to bridged channels and I do like measuring phase :)

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Out of curiosity, someone should ask this possible ex-Jensen tech if the same thing occurs when you bridge a 4 channel amp to 2 channels.

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Originally Posted by Euphonic

Out of curiosity, someone should ask this possible ex-Jensen tech if the same thing occurs when you bridge a 4 channel amp to 2 channels.

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That’s the exact same just done twice

Btw, I am not trying to criticize him but, trying to understand what he was saying.

Btw, he is a well known Amp guy but, as far as I know he didn't work for Jensen or Phase Liner.

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Originally Posted by dumdum

That’s the exact same just done twice

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I know, but companies like a/d/s/ didn't make powerful 2 channel amps so people would bridge the 4 channel models for more power.

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Originally Posted by KillerBox

Btw, I am not trying to criticize him but, trying to understand what he was saying.

Btw, he is a well known Amp guy but, as far as I know he didn't work for Jensen or Phase Liner.

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He could be a genius, but a statement such as that requires an explanation that makes sense.

From all of the amps measured over at ASR, only very poor ones have phase mismatch issues. Most have channels that are identical.

Even this dual da10004d amp had channel matching in phase (top left graph)

https://www.audiosciencereview.com/f...plifier.25765/
https://www.audiosciencereview.com/f...-d-png.147410/

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Originally Posted by Jdunk54nl

From all of the amps measured over at ASR, only very poor ones have phase mismatch issues. Most have channels that are identical.

Even this dual da10004d amp had channel matching in phase (top left graph)

https://www.audiosciencereview.com/f...plifier.25765/
https://www.audiosciencereview.com/f...-d-png.147410/

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Not sure where you have seen phase at high freq measured? A single freq doesn’t confirm what this guy was saying, low freqs are simpler according to this engineer, I will ask amir if he can measure some to check, any amp should exhibit this stability if bridgable I would think…

by the way I’m not saying there’s any weight to the engineers statement, just that his statement was that low freqs are not where issues arise

I hope this isn't true...A few weeks back I emailed with ARC asking what the best way was to power a 4Ohm midbass and a 8Ohm midrange to get over 150W per driver using SE4200s. One of the suggestions was to use 2 SE4200, one for the left and one for the right with the channels bridged. He said they do this all the time in competition cars. I'm thinking ARC would know if that caused phase issues...

Unless the "well known car audio guy" comes over here and starts posting, this isn't a thing.

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Originally Posted by Justin Zazzi

Unless the "well known car audio guy" comes over here and starts posting, this isn't a thing.

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= Ray Rayfield and I think the post referenced was in the SSQ group. https://www.facebook.com/ray.rayfield

He's no dummy!

Edit: maybe not SSQ. Possibly someone has the link.

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Originally Posted by DaveG

= Ray Rayfield and I think the post referenced was in the SSQ group. https://www.facebook.com/ray.rayfield

He's no dummy!

Edit: maybe not SSQ. Possibly someone has the link.

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There is your problem....you are going to facebook for information..... ;)

Get off that crap...even facebook employees know how bad it is due to internal research!

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Originally Posted by Jdunk54nl

There is your problem....you are going to facebook for information..... ;)

Get off that crap...even facebook employees know how bad it is due to internal research!

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How about Google?

https://www.google.com/search?q=ray+...hrome&ie=UTF-8

That doesn't tell me much about anything that he knows or doesn't know. I can see his education and career information from the linked in profile, but even then, it doesn't make me want to believe everything he says. Plenty of people with fancy titles don't know about how things work, and his formal education also doesn't support his potential knowledge.

I am also not going to spend the time in here researching Ray Rayfield beyond this. If he wants to join this forum and give us an explanation as to why this statement was made, I'll listen. But currently, this is smelling like snake oil to me to sell more expensive amps instead of cheaper amps that you can bridge to get more power.

Otherwise, as Justin said, this isn't a thing in a well designed product, could very well be in a poor designed product though.

Ray's the head honcho at Linear Power

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Originally Posted by BigAl205

Ray's the head honcho at Linear Power

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He is, after their resurrection in 2009-2010. I do know back in the day on Diyma, he and Linear Power had both fans and detractors. I'm not sure if he's right about this phase issue or not, but an awful lot of people have run bridged amps over the years. You'd think someone would have noticed this issue prior to Ray stating it.

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Originally Posted by BigAl205

Ray's the head honcho at Linear Power

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That doesn't tell me about his technical reasoning behind the statement he made, just that he knows how to run a company. Lots of people that run companies have no clue how their products function on a technical level. Shoot, some managers break things because they don't know how they actually work. They are great at their job though, managing people/company.

This will be my last comment on this thread unless Ray comes in here and can explain the technical reason behind his statement with data backing it up (or anyone for that matter)

Otherwise I am calling BS on this one as everything I have seen shows this being a non issue in well designed products.

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Originally Posted by Jdunk54nl

That doesn't tell me about his technical reasoning behind the statement he made, just that he knows how to run a company. Lots of people that run companies have no clue how their products function on a technical level. Shoot, some managers break things because they don't know how they actually work. They are great at their job though, managing people/company.

This will be my last comment on this thread unless Ray comes in here and can explain the technical reason behind his statement with data backing it up (or anyone for that matter)

Otherwise I am calling BS on this one as everything I have seen shows this being a non issue in well designed products.

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I agree with you, his initial assessment doesn't make sense to me.

...neither does the price of their equipment

I wouldn't put too much value in what Ray has to say. He's made a lot of bs claims over the years.

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Originally Posted by ca90ss

I wouldn't put too much value in what Ray has to say. He's made a lot of bs claims over the years.

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I hope he's just trolling. Then again his is Ray we're talking about. He has become a laughing stock to a lot of people including me.