Speaker connection

[Kamranbites]

I have 4 bookshelf speakers 2 Kenwood (45w each 6 ohms) 2 aiwa (45w 6ohms each) I bought a amplifier brand nobound ns-20g 

200w amplifier so i need help connection my speakers to my amp. In your opinion what is best should I connect my speakers in parallel or series my amplifier supports only 2 channel and Speaker Impedance   4~8ohm

 

Thanks for making your way till here  

 

[OhYou_]

well if the amp only supports 4 ohm, the effective 3 ohm of them in parallel could cause problems.

I would first try parallel anyway, and if you notice clipping at higher volumes, switch to series.

[cmndr]

I would NOT try to hack dissimilar speakers together on a 2 channel amp. 

What is your goal? If it's to get surround sound, you're better off buying an old, cheap AVR for like $100 off craigslist or FB market and actually doing it right instead of fiddling with running dissimilar speakers in a series or in parallel off of an amp that would perpetually be struggling. 

 

[Kamranbites]

8 hours ago, OhYou_ said:

well if the amp only supports 4 ohm, the effective 3 ohm of them in parallel could cause problems.

I would first try parallel anyway, and if you notice clipping at higher volumes, switch to series.

Tried using series and parallel wiring no clipping of sound under both methods 

[Kamranbites]

6 hours ago, cmndr said:

I would NOT try to hack dissimilar speakers together on a 2 channel amp. 

What is your goal? If it's to get surround sound, you're better off buying an old, cheap AVR for like $100 off craigslist or FB market and actually doing it right instead of fiddling with running dissimilar speakers in a series or in parallel off of an amp that would perpetually be struggling. 

 

I tried looking for 4 channel amp but i was unable to find one moreover this speaker are very old and spending more on them i thought would not be a great idea moreover finding a 6ohms 4 channel amplifier is hard what i usually see  is 2.1,5.1 7.1, my speakers are 3way speaker so my requirement will be 4 channel exactly and  6ohms 

[cmndr]

Any reason why you wouldn't be fine with just two speakers? Stereo done well usually beats janky done poorly. 

What's your goal?

As stated, if it's "surround sound" having the same sound in stereo repeated twice is NOT what you're looking for. 

There's used $100ish AVRs that'll actually do proper sound processing. People practically give them away since anything pre-HDMI is suboptimal for a TV set up. 

[Kamranbites]

1 hour ago, cmndr said:

Any reason why you wouldn't be fine with just two speakers? Stereo done well usually beats janky done poorly. 

What's your goal?

As stated, if it's "surround sound" having the same sound in stereo repeated twice is NOT what you're looking for. 

There's used $100ish AVRs that'll actually do proper sound processing. People practically give them away since anything pre-HDMI is suboptimal for a TV set up. 

Can use just 2 speaker but the other two will be just lying around moreover when connecting this two the sound increase drastically moreover the amp i bought is 200w connection just 2- 45w Speaker don't sound good speaker might not handle the sound output also we cannot utilise the full power of amp  about AVR i looked but very hard to find 6ohms 4 channel amp so got a mini amp it is protable so less space consuming and can handle 4 speaker as it is 200w RMS so i thought it would be best deal  4 speaker 45+45+45+45

(180)  one channel aiwa and Kenwood speaker other channel same so it might be little bit balanced on both side same configuration so no conflicts of watts or ohms or brand both channel has same brand and same specs speakers 

[cmndr]

6 hours ago, Kamranbites said:

Can use just 2 speaker but the other two will be just lying around moreover when connecting this two the sound increase drastically

Generally speaking, more speakers means more comb filtering, which is awful for sound quality. The sound from one speaker ends up partially cancelling out the other speaker. 
https://www.sweetwater.com/insync/what-is-it-comb-filtering/#:~:text=Eliminate Comb Filtering-,What Is Comb Filtering%3F,%2C up to 15ms–20ms.
 

6 hours ago, Kamranbites said:

moreover the amp i bought is 200w connection just 2- 45w Speaker don't sound good speaker might not handle the sound output also we cannot utilise the full power of amp 

Wattage is more like a speed limit than a requirement. Chances are your amp will spend 99.9% of its life producing under 10W of output. 

A speaker with an efficiency of 85dB at 1 meter per watt will be "loud enough" for most people using 1-5W unless you're really far away. This is a fairly low efficiency rating for a speaker. 

6 hours ago, Kamranbites said:

about AVR i looked but very hard to find 6ohms 4 channel amp so got a mini amp it is protable so less space consuming

Most AVRs can handle between 4-8Ohms. Even really cheap, old ones. 
Also, 4 channel only AVRs are rare but 5 channel AVRs are SUPER common. You just don't hook up the center channel.

The space saving argument is valid though. 

6 hours ago, Kamranbites said:

and can handle 4 speaker as it is 200w RMS so i thought it would be best deal  4 speaker 45+45+45+45 (180)

It doesn't work that way.
With non-identical speakers, the resistance at a given frequency will be different. If you're pulling 45W from one speaker, it's almost certain that the other one will be either higher or lower than that because the resistance at a given frequency WILL be different. The ohm figure is usually kind of a "medium bad" overall figure but it WILL vary. 

Also, unless you're playing in a large open field, you won't be hitting anywhere close to 45W. 

As an FYI, the job of a receiver isn't just to power the 4 speakers, it's to take a signal and to split up the frequencies going to all of the speakers so that the sound doesn't turn out like mud. 

FYI, 200W near field is enough to cause permanent hearing damage. My AVR can probably pump out a few hundred watts, I'm probably running it at around 0.05 - 5W 99% of the time. 

I'll use my own (err similar) speakers as an example. 
The minimum impedance is "only" 3.6Ohms. There's good chunks of the frequency where it's over 14Ohms though. 


If you compare against a different set of speakers I own, there are similarities but they're NOT the same. 

6 hours ago, Kamranbites said:

one channel aiwa and Kenwood speaker other channel same so it might be little bit balanced on both side same configuration so no conflicts of watts or ohms or brand both channel has same brand and same specs speakers 

I mean it'll probably work, especially if you're not listening to things at high power output levels, but you really would be better off picking the better speaker and sticking with that, assuming it's all in the same room. 

 

[Kamranbites]

5 hours ago, HenrySalayne said:

Please punctuate your posts. Nobody can understand this mess.

 

Just use 2 identical speaker (one for each channel) and be done with it. "more is better" is literally wrong when it comes to speakers.

Ignore the power rating of your speakers and your amplifier. It doesn't matter if it's in the two or three digit range and most ratings are just made up numbers anyway.

Regarding impedance. you only need to make sure your amplifier's minimum impedance is lower than the impedance of the speakers you are connecting. If you have 6 Ohm speakers, an amp with a minimum impedance of 4 Ohm is fine, an amp with a minimum impedance of 8 ohm doesn't work.

More is better ya it is wrong but in my case i am just matching my amplifier wattage with my speaker wattage as i have mentioned before my amp is true 200w RMS and connecting 4 45w speaker gives me 180rms which is ok if i just connect one per channel amplifier will blow up my speakers moreover i want to fully utilise my amplifier 200w

[Kamranbites]

51 minutes ago, cmndr said:

Generally speaking, more speakers means more comb filtering, which is awful for sound quality. The sound from one speaker ends up partially cancelling out the other speaker. 
https://www.sweetwater.com/insync/what-is-it-comb-filtering/#:~:text=Eliminate Comb Filtering-,What Is Comb Filtering%3F,%2C up to 15ms–20ms.
 

Wattage is more like a speed limit than a requirement. Chances are your amp will spend 99.9% of its life producing under 10W of output. 

A speaker with an efficiency of 85dB at 1 meter per watt will be "loud enough" for most people using 1-5W unless you're really far away. This is a fairly low efficiency rating for a speaker. 

Most AVRs can handle between 4-8Ohms. Even really cheap, old ones. 
Also, 4 channel only AVRs are rare but 5 channel AVRs are SUPER common. You just don't hook up the center channel.

The space saving argument is valid though. 

It doesn't work that way.
With non-identical speakers, the resistance at a given frequency will be different. If you're pulling 45W from one speaker, it's almost certain that the other one will be either higher or lower than that because the resistance at a given frequency WILL be different. The ohm figure is usually kind of a "medium bad" overall figure but it WILL vary. 

Also, unless you're playing in a large open field, you won't be hitting anywhere close to 45W. 

As an FYI, the job of a receiver isn't just to power the 4 speakers, it's to take a signal and to split up the frequencies going to all of the speakers so that the sound doesn't turn out like mud. 

FYI, 200W near field is enough to cause permanent hearing damage. My AVR can probably pump out a few hundred watts, I'm probably running it at around 0.05 - 5W 99% of the time. 

I'll use my own (err similar) speakers as an example. 
The minimum impedance is "only" 3.6Ohms. There's good chunks of the frequency where it's over 14Ohms though. 


If you compare against a different set of speakers I own, there are similarities but they're NOT the same. 

I mean it'll probably work, especially if you're not listening to things at high power output levels, but you really would be better off picking the better speaker and sticking with that, assuming it's all in the same room. 

 

Thanks for the explanation so you expect me to just use 2 speaker instead of 4 right ? 

[cmndr]

In most cases you're better off just using two speakers that are well positioned. 

There are exceptions in either VERY large rooms or if you're trying to play in two different rooms. Doubling up on speakers doesn't make the sound twice as loud (about 10dB to feel like it's twice as loud) as it only increases the sound pressure output by 3 dB (not counting in certain frequencies getting outright cancelled by comb filtering). There are some benefits if you want to cover twice as much space (think placing the other speaks 20 meters away). 

Ideally you go for a layout somewhat similar to this, with the tweeters on each speaker pointed towards your ears. 

 

 

35 minutes ago, Kamranbites said:

More is better ya it is wrong but in my case i am just matching my amplifier wattage with my speaker wattage as i have mentioned before my amp is true 200w RMS and connecting 4 45w speaker gives me 180rms which is ok if i just connect one per channel amplifier will blow up my speakers moreover i want to fully utilise my amplifier 200w

Chances are your tiny, class D amplifier rated for 200W isn't going to really be able to sustain more than 50-100W in practice. The ratings put on those things are borderline lies. They'll only do that at a VERY VERY low resistance that isn't seen in the real world. 

You're more likely to damage the speakers or amps with mismatched speakers than with  an "overpowered" amplifier. 


Just don't play VERY loud things at the loudest possible loudness. 

This shouldn't be hard. If you're targeting a reference level of 85dB (still very loud and louder than I find comfortable) and you have 85dB/m/w efficient speakers (kind of meh/normalish) and you're listening to them from 3 meters away, you'll use under 9W. If there are very short transient peaks of 95dB the amp will pull at most 90W. 


I want to emphasize, 200W for most speakers at a normal listening position (not 3m, maybe 1meter - as in you'd expect severe discomfort/pain and permanent hearing damage within 5 minutes) is enough to cause almost immediate and permanent hearing damage. You're NOT going to hit this limit in the real world. 

[Kamranbites]

1 hour ago, cmndr said:

In most cases you're better off just using two speakers that are well positioned. 

There are exceptions in either VERY large rooms or if you're trying to play in two different rooms. Doubling up on speakers doesn't make the sound twice as loud (about 10dB to feel like it's twice as loud) as it only increases the sound pressure output by 3 dB (not counting in certain frequencies getting outright cancelled by comb filtering). There are some benefits if you want to cover twice as much space (think placing the other speaks 20 meters away). 

Ideally you go for a layout somewhat similar to this, with the tweeters on each speaker pointed towards your ears. 

 

 

Chances are your tiny, class D amplifier rated for 200W isn't going to really be able to sustain more than 50-100W in practice. The ratings put on those things are borderline lies. They'll only do that at a VERY VERY low resistance that isn't seen in the real world. 

You're more likely to damage the speakers or amps with mismatched speakers than with  an "overpowered" amplifier. 


Just don't play VERY loud things at the loudest possible loudness. 

This shouldn't be hard. If you're targeting a reference level of 85dB (still very loud and louder than I find comfortable) and you have 85dB/m/w efficient speakers (kind of meh/normalish) and you're listening to them from 3 meters away, you'll use under 9W. If there are very short transient peaks of 95dB the amp will pull at most 90W. 


I want to emphasize, 200W for most speakers at a normal listening position (not 3m, maybe 1meter - as in you'd expect severe discomfort/pain and permanent hearing damage within 5 minutes) is enough to cause almost immediate and permanent hearing damage. You're NOT going to hit this limit in the real world. 

As per online reviews and the IC it looks like it is 200w RMS amplifier moreover it is a reputed brand (output power is improved to 200W American TI Texas Instruments TPA3116 ×2) and about over power amplifiers that what my fear is there is no problem in just using two of my speakers but i dought my 45w aiwa pair might not be able to handle them compared to connecting 4 at once there is no distortion on full volume nor heat issues but i fear due to ohms mismatch as connecting 6ohms together in parallel it will be 3 ohms per channel which is less then the rated capacity of my amplifier (4-8)

[Kamranbites]

1 hour ago, cmndr said:

In most cases you're better off just using two speakers that are well positioned. 

There are exceptions in either VERY large rooms or if you're trying to play in two different rooms. Doubling up on speakers doesn't make the sound twice as loud (about 10dB to feel like it's twice as loud) as it only increases the sound pressure output by 3 dB (not counting in certain frequencies getting outright cancelled by comb filtering). There are some benefits if you want to cover twice as much space (think placing the other speaks 20 meters away). 

Ideally you go for a layout somewhat similar to this, with the tweeters on each speaker pointed towards your ears. 

 

 

Chances are your tiny, class D amplifier rated for 200W isn't going to really be able to sustain more than 50-100W in practice. The ratings put on those things are borderline lies. They'll only do that at a VERY VERY low resistance that isn't seen in the real world. 

You're more likely to damage the speakers or amps with mismatched speakers than with  an "overpowered" amplifier. 


Just don't play VERY loud things at the loudest possible loudness. 

This shouldn't be hard. If you're targeting a reference level of 85dB (still very loud and louder than I find comfortable) and you have 85dB/m/w efficient speakers (kind of meh/normalish) and you're listening to them from 3 meters away, you'll use under 9W. If there are very short transient peaks of 95dB the amp will pull at most 90W. 


I want to emphasize, 200W for most speakers at a normal listening position (not 3m, maybe 1meter - as in you'd expect severe discomfort/pain and permanent hearing damage within 5 minutes) is enough to cause almost immediate and permanent hearing damage. You're NOT going to hit this limit in the real world. 

Pics of my speakers and config 

[cmndr]

That's about as bad as it could get from a comb filtering perspective. I had initially thought you were putting the speakers in kind of a corner layout (which isn't the worst thing in the world) or with one pair at front and one pair on the sides. Something like this based off of the official dolby spec (which is what movies assume is the layout when they do mastering for home theater set ups). https://www.dolby.com/siteassets/about/support/guide/setup-guides/5.1-virtual-speakers-setup/5_1_spkrplc.jpg?width=2880&quality=80




You basically get all the "bad things" mentioned in this topic but way worse since the effect is MORE than doubled up.
https://www.avsforum.com/threads/what-disadvantage-to-using-two-bookshelf-speakers-as-a-single-center-channel.1424389/


Imagine a mono signal (same signal going to the left and the right channels - basically any time when there's a voice). On the bottom set of speakers you'll have noise cancellation at a different set of frequencies (imagine deep gaps in the sound at say 500Hz, 1000Hz, 2000Hz, 4000Hz, 8000Hz, 16000Hz, etc) because of wave cancellations. Now imagine the top two speakers have gaps at 800Hz, 1600Hz, 3200Hz, 6400Hz, 12800Hz.... now imaging the top left and the center left (along with the mirrored pair) has gaps at 600Hz, 1200Hz, 2400Hz, 4800Hz, 9600Hz, 19200Hz... Now imagine the top left and the right speaker have gaps at 700Hz, 1400Hz, 2800Hz, 5600Hz, 11200Hz...

It's basically going to be a mess. This doesn't even touch on the peaks (not as much of an issue, it's only +3dB). 
Also there might be some mismatches due to difference in group delay.

Your sound's wave form is going to be a muddy, spiky, smeared mess relative to just using the two best speakers. 

You'd be better off disconnecting the bottom speakers and using them as speaker stands for the top speakers. 

If you want to fact check that try playing this - Ideally everything is very close to the same loudness after around 200Hz or so. If there's gaps or sudden loudness spikes... that's comb filtering. 
https://www.youtube.com/watch?v=EWkekP1f1Z4

--------------------------------------------

Not fully related to the above but your sound stage and imaging is going to be messed up by the "fake" center. 
https://www.youtube.com/watch?v=4CuJqtNdcJU

Compare that song using headphones vs 2 speakers (you should be able to close your eyes and pin point the location of objects) vs 2 speakers twice. 

[Fendrick]

You will be completely fine, did a similar thing for a very powerful bluetooth speaker.

 

https://www.diymobileaudio.com/threads/what-will-happen-if-i-wire-1-4-ohm-tweeter-with-2-8-ohm-full-range-mid-bass-on-the-same-amp.455413/

 

 

[Fendrick]

7 minutes ago, cmndr said:

That's about as bad as it could get from a comb filtering perspective. I had initially thought you were putting the speakers in kind of a corner layout (which isn't the worst thing in the world) or with one pair at front and one pair on the sides


You basically get all the "bad things" mentioned in this topic but way worse since the effect is MORE than doubled up.
https://www.avsforum.com/threads/what-disadvantage-to-using-two-bookshelf-speakers-as-a-single-center-channel.1424389/


Imagine a mono signal (same signal going to the left and the right channels). On the bottom set of speakers you'll have noise cancellation at a different set of frequencies (imagine deep gaps in the sound at say 500Hz, 1000Hz, 2000Hz, 4000Hz, 8000Hz, 16000Hz, etc) because of wave cancellations. Now imagine the top two speakers have gaps at 800Hz, 1600Hz, 3200Hz, 6400Hz, 12800Hz.... now imaging the top left and the center left (along with the mirrored pair) has gaps at 600Hz, 1200Hz, 2400Hz, 4800Hz, 9600Hz, 19200Hz... Now imagine the top left and the right speaker have gaps at 700Hz, 1400Hz, 2800Hz, 5600Hz, 11200Hz...

It's basically going to be a mess. This doesn't even touch on the peaks (not as much of an issue, it's only +3dB). 
Also there might be some mismatches due to difference in group delay

Your sound's wave form is going to be a muddy, smeared mess relative to just using the two best speakers. 

You'd be better off disconnecting the bottom speakers and using them as speaker stands for the top speakers. 

You apply way too much theory to what would in practice be likely completely fine.

[cmndr]

5 minutes ago, Fendrick said:

You apply way too much theory to what would in practice be likely completely fine.

I'm actually pushing for testing it instead of just going with what I stated. Also backing it up with links to standards and discussion

Though yes, there's A LOT of theoretical reasons why it does more harm than good to repeat the same signal. 

It's basically a worse version of this
https://www.audiosciencereview.com/forum/index.php?threads/the-problem-with-many-center-channel-speakers-by-erin.30716/

 

As an FYI you can actually play with a comb filtering demo here - https://www.falstad.com/ripple/

[Fendrick]

3 minutes ago, cmndr said:

I'm actually pushing for testing it instead of just going with what I stated. Also backing it up with links to standards and discussion

Though yes, there's A LOT of theoretical reasons why it does more harm than good to repeat the same signal. 

It's basically a worse version of this
https://www.audiosciencereview.com/forum/index.php?threads/the-problem-with-many-center-channel-speakers-by-erin.30716/

I am sure this guy will get great sound out of it, the only thing that will change is the maximum volume he can push from the amp since the OHM's will drop, this happened to my amp powering the bluetooth speaker I made, 2 8ohm driver with a 4 ohm bullet tweeter drops the total resistance on the amp, however it can still play cleanly up to 75% of the dial, around 85% is where we hear distortion, at the point I am at 75% dial it is ear piercingly loud and need to turn it down anyway.

 

It is also clear the OP is not an audiophile, just help them hear their sound safely, no one cares.

[Kamranbites]

16 minutes ago, cmndr said:

That's about as bad as it could get from a comb filtering perspective. I had initially thought you were putting the speakers in kind of a corner layout (which isn't the worst thing in the world) or with one pair at front and one pair on the sides. Something like this based off of the official dolby spec (which is what movies assume is the layout when they do mastering for home theater set ups). https://www.dolby.com/siteassets/about/support/guide/setup-guides/5.1-virtual-speakers-setup/5_1_spkrplc.jpg?width=2880&quality=80




You basically get all the "bad things" mentioned in this topic but way worse since the effect is MORE than doubled up.
https://www.avsforum.com/threads/what-disadvantage-to-using-two-bookshelf-speakers-as-a-single-center-channel.1424389/


Imagine a mono signal (same signal going to the left and the right channels - basically any time when there's a voice). On the bottom set of speakers you'll have noise cancellation at a different set of frequencies (imagine deep gaps in the sound at say 500Hz, 1000Hz, 2000Hz, 4000Hz, 8000Hz, 16000Hz, etc) because of wave cancellations. Now imagine the top two speakers have gaps at 800Hz, 1600Hz, 3200Hz, 6400Hz, 12800Hz.... now imaging the top left and the center left (along with the mirrored pair) has gaps at 600Hz, 1200Hz, 2400Hz, 4800Hz, 9600Hz, 19200Hz... Now imagine the top left and the right speaker have gaps at 700Hz, 1400Hz, 2800Hz, 5600Hz, 11200Hz...

It's basically going to be a mess. This doesn't even touch on the peaks (not as much of an issue, it's only +3dB). 
Also there might be some mismatches due to difference in group delay.

Your sound's wave form is going to be a muddy, spiky, smeared mess relative to just using the two best speakers. 

You'd be better off disconnecting the bottom speakers and using them as speaker stands for the top speakers. 

If you want to fact check that try playing this - Ideally everything is very close to the same loudness after around 200Hz or so. If there's gaps or sudden loudness spikes... that's comb filtering. 
https://www.youtube.com/watch?v=EWkekP1f1Z4

--------------------------------------------

Not fully related to the above but your sound stage and imaging is going to be messed up by the "fake" center. 
https://www.youtube.com/watch?v=4CuJqtNdcJU

Compare that song using headphones vs 2 speakers (you should be able to close your eyes and pin point the location of objects) vs 2 speakers twice. 

That bottom speaker looks like cente speaker but are connected in parallel with the aiwa speaker  left one with left and right one with right 

[Kamranbites]

21 minutes ago, TechlessBro said:

Aesthetic sure.

Acoustics no.
 

There isn’t anything really wrong with what you are doing but it isn’t ideal.

 

this is all pretty much already covered by cmndr above anyway.

 

Each set of speakers have different tone and responses, even the volume per watt (sensitivity) is different. When mixed and matched they muddy up everything just a tiny bit.

 

Sound stage how wide and where instruments are placed when you close your eyes will be messed up. Test that out by running 2 and then the 4 speakers repeating the same song.

Since you have the same channel from two different locations and that messes up the timing your brain uses to determine where the sound is coming from.

Your brain is sensitive enough to determine the time a sound takes to arrive at each ear to work out the direction it came from.
 

So what you have both influences the perceived width and clarity.

 

You could try the second set pointing outwards to bounce off the walls as fill then the timings would be longer and not as bad.

If it sounds good to you and you like it then keep it. You could just unhook the middle pair and have it for looks. For parties or groups of people around many speakers at low volume actually work fine.
 

Worst case you learn about audio through practical experimentation.

 

Audiophile is a bad word. Acoustics is not.
Learning about one can make you poor the other can earn you money.

When connecting just 2 of them the sound is ok but when all 4 are working it gives a theator effect with heavy bass. In  both scenario ( 1+1, 2+2) voices is not getting distorted but huge difference in loudness and bass 

[cmndr]

There's no "center channel" unless there's an AVR that takes out identical information that would otherwise go to the L+R and extracts it to only play in the center. 

For what it's worth my AVR has an option for "center channel spread" which plays the same sound on the center and the L+R. 
For laughs I've tested it (also had a friend confirm and I didn't tell her which was "better")

For my set up L+R with center disabled > center enables > sound on all 3. The comb filtering from having 3 tweeters and 4 woofers was a downgrade. 
It's actually not THAT far from OP's set up, though there's probably a little bit of logic on the AVR to make it less bad.


 

[Fendrick]

Just now, Kamranbites said:

When connecting just 2 of them the sound is ok but when all 4 are working it gives a theator effect with heavy bass. In  both scenario ( 1+1, 2+2) voices is not getting distorted but huge difference in loudness and bass 

Did your amp come with a 32v 5 amp power supply?

[Kamranbites]

1 minute ago, Fendrick said:

Did your amp come with a 32v 5 amp power supply?

While ordering  i ordered it without power supply as it was way less 19v 4a. so i ordered charger separately which is 20v 10A HP adaptor 

[Kamranbites]

28 minutes ago, cmndr said:

That's about as bad as it could get from a comb filtering perspective. I had initially thought you were putting the speakers in kind of a corner layout (which isn't the worst thing in the world) or with one pair at front and one pair on the sides. Something like this based off of the official dolby spec (which is what movies assume is the layout when they do mastering for home theater set ups). https://www.dolby.com/siteassets/about/support/guide/setup-guides/5.1-virtual-speakers-setup/5_1_spkrplc.jpg?width=2880&quality=80




You basically get all the "bad things" mentioned in this topic but way worse since the effect is MORE than doubled up.
https://www.avsforum.com/threads/what-disadvantage-to-using-two-bookshelf-speakers-as-a-single-center-channel.1424389/


Imagine a mono signal (same signal going to the left and the right channels - basically any time when there's a voice). On the bottom set of speakers you'll have noise cancellation at a different set of frequencies (imagine deep gaps in the sound at say 500Hz, 1000Hz, 2000Hz, 4000Hz, 8000Hz, 16000Hz, etc) because of wave cancellations. Now imagine the top two speakers have gaps at 800Hz, 1600Hz, 3200Hz, 6400Hz, 12800Hz.... now imaging the top left and the center left (along with the mirrored pair) has gaps at 600Hz, 1200Hz, 2400Hz, 4800Hz, 9600Hz, 19200Hz... Now imagine the top left and the right speaker have gaps at 700Hz, 1400Hz, 2800Hz, 5600Hz, 11200Hz...

It's basically going to be a mess. This doesn't even touch on the peaks (not as much of an issue, it's only +3dB). 
Also there might be some mismatches due to difference in group delay.

Your sound's wave form is going to be a muddy, spiky, smeared mess relative to just using the two best speakers. 

You'd be better off disconnecting the bottom speakers and using them as speaker stands for the top speakers. 

If you want to fact check that try playing this - Ideally everything is very close to the same loudness after around 200Hz or so. If there's gaps or sudden loudness spikes... that's comb filtering. 
https://www.youtube.com/watch?v=EWkekP1f1Z4

--------------------------------------------

Not fully related to the above but your sound stage and imaging is going to be messed up by the "fake" center. 
https://www.youtube.com/watch?v=4CuJqtNdcJU

Compare that song using headphones vs 2 speakers (you should be able to close your eyes and pin point the location of objects) vs 2 speakers twice. 

And that bottom speaker are not one both are separate bookshelf speakers just for better view i have placed them that way 

[cmndr]

As an FYI, most amps want a very specific power input. It's possible that 20V input would work (not sure about your unit) but it could also slowly be destroying the amp. Check your amp's  power specificiations. 

With audio stuff, more stuff is NOT better. 

You probably only need 10W of amplification for bookshelf speakers. 200W makes sense for a subwoofer or a series of tactile transducers.