Noob Question Re: Bridging Any Stereo to Mono - diyAudio
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Old 3rd May 2013, 05:24 AM   #1
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Default Noob Question Re: Bridging Any Stereo to Mono

I am looking at setting up a pair of amps to run as mono-blocks and online several sites have posited this as a solution: I want mono blocks just because I can.

Quote:
Connect the speaker leads across the two red binding posts.... There is no connection to the black posts.
So what is going to happen should I attempt this? Is my GFCI going to melt? Will my drivers fuse? Silence? Sparks?

Or just a properly functioning bridged amp with increased impedance handling and wattage with a mono output of the input?

Will this affect tube amps more than SS (and I am guessing the answer is yes to tubes no likey)?
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Old 3rd May 2013, 10:14 AM   #2
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if your amplifier is rated for 8ohms speakers then in bridged you MUST use 16ohms speaker or higher.

If your amplifier is rated for 4ohms speakers then in bridged you MUST use 8ohms speaker or higher.

If your amplifier is rated as stable, or safe, into 4r0 resistor, this probably means it can drive an 8ohms speaker.
4r0 (resistive load) DOES NOT mean it can drive a 4ohms speaker that is reactive as all speakers are.

The fact that you are asking these questions tells me your are not safe to be let loose on using any mains equipment beyond the manufacturer's recommendations.
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Old 3rd May 2013, 11:52 AM   #3
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Quote:
Originally Posted by AndrewT View Post
The fact that you are asking these questions tells me your are not safe to be let loose on using any mains equipment beyond the manufacturer's recommendations.
Thank you for the advice.
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Old 3rd May 2013, 01:26 PM   #4
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Quote:
Originally Posted by AndrewT View Post
The fact that you are asking these questions tells me your are not safe to be let loose on using any mains equipment beyond the manufacturer's recommendations.
Thank you for the advice.
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Old 3rd May 2013, 01:49 PM   #5
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You'd need four mono-blocks for two speakers, i.e., stereo. There's another catch. Bridged operation requires that one amplifier be driven by an inverted signal. You'd need a way to do that. IMO you'd be better off with a pair of stereo amps designed for bridged operation like most Crown power amps or other commercial/pro/reinforcement/pa/guitar amps. You flip the stereo/bridged switch on the back, connect to one input, and the amp takes care of the rest. Because they designed it for bridge operation there's at least some probability that it will survive!
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Old 9th June 2014, 03:17 PM   #6
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Quote:
Originally Posted by AndrewT View Post
The fact that you are asking these questions tells me your are not safe to be let loose on using any mains equipment beyond the manufacturer's recommendations.
The fact that you penned such a reply tells me that you are not safe to be let loose in any instructional, training, or educational environment.
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Old 21st July 2014, 05:37 AM   #7
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Quote:
Originally Posted by Conrad Hoffman View Post
You'd need four mono-blocks for two speakers, i.e., stereo. There's another catch. Bridged operation requires that one amplifier be driven by an inverted signal. You'd need a way to do that. IMO you'd be better off with a pair of stereo amps designed for bridged operation like most Crown power amps or other commercial/pro/reinforcement/pa/guitar amps. You flip the stereo/bridged switch on the back, connect to one input, and the amp takes care of the rest. Because they designed it for bridge operation there's at least some probability that it will survive!
I have tried to kludge my valve amps and no joy, so they wont do it. No blue flames, just silence when attempting to run one channel from both ground taps. Don't know the circuit topology.

Another way is to run an RCA-Y-Splitter to split each single male to two and to bi-wire each side.

Each amp would receive two channels of identical signal, each channel of the amp would have an output, and both outputs would lead to one speaker/driver/listening channel. Maybe this could cause issues with each side seeing the same bridged load, but should not be an issue.
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Old 21st July 2014, 06:48 AM   #8
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Quote:
Originally Posted by miragem3i View Post
I have tried to kludge my valve amps and no joy, so they wont do it. No blue flames, just silence when attempting to run one channel from both ground taps. Don't know the circuit topology.

Another way is to run an RCA-Y-Splitter to split each single male to two and to bi-wire each side.

Each amp would receive two channels of identical signal, each channel of the amp would have an output, and both outputs would lead to one speaker/driver/listening channel. Maybe this could cause issues with each side seeing the same bridged load, but should not be an issue.
Y-splitter will not solve the problem. The signal, going to one of the bridged amplifiers, needs to be inverted (180 degrees phase shift). See here for the proper bridging adapter:

Bridging Adapter For Power Amplifiers

Andrew's comments are 100% valid.

Cheers,
Valery

P.S. Read about the bridging pitfalls carefully, right above the schematic in the article.
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Last edited by vzaichenko; 21st July 2014 at 06:56 AM.
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Old 21st July 2014, 01:28 PM   #9
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Thanks for the circuit suggestion.

Quote:
Originally Posted by vzaichenko View Post
Andrew's comments are 100% valid.
I am just now realising that this site is run by and for terminal degree'd engineers ONLY and that no other points of view are all allowed. It's not really a hobbiest site, is it? More like a ''seek approbation for your idea from the engineers'' site.

Andrew and you could have worded it this way:
""You are asking a lot of beginner questions that an Engineer would immediately not ask. When you work on circuits be careful - but you seem responsible and cautious, if not highly educated in circuit topology. Just use basic common sense and a few simple rules and you will be fine. Here is the link to basic safety practices as a revision. Begin with low-V DC when you experiment.""

THAT'S how you could phrase it.

Last edited by miragem3i; 21st July 2014 at 01:34 PM.
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Old 21st July 2014, 01:58 PM   #10
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Hi miragem3i,

My answer to the first sentebce is "No"
This is a great international community for everyone, regardless of knowledge, experience, etc. We try to help, but as most of us communicate in many threads, we normally put things right to the point.

Sorry if it looked "offensive" - believe me, nobody meant it.

If you have more questions, including the ones with regards to bridging, you are welcome - me or somebody else will try to help

Best regards,
Valery
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