Question (DIY Audio) Questions in regards to my set up.

dancerehab

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I have a pair of sony bookshelfs (SS-CSPZ50 50W 6Ohms) that I have been using on my pc with a lepai mini amplifier(Lepai LP-2020TI). Yesterday i bought a used car amp (semtoni 300watt amplifier) This exact amp though branded semtoni. It has 4 channels each rated at 75W but 40watts continuous power. I tested one of my bookshelfs on the amp and it sounded so damn good. Today i also got an extra Sony Hi-fi speaker (SS-EX6) one rated at around 70 watts, 6Ohms. I tested the speaker and it also sounded good(i tested at low volume because it's at night though). Later today I get to test all the three speakers on the big amp. Do you guys think that my configuration is okay so far for a budget music/movie watching system? NB: I also have a cheap mini active sub-woofer that i plan to add to the set up once i balance all the three speakers.
 
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delaro

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Herald
  1. You should add Speakers in sets preferable at the same ohm loads.
  2. Odd numbers are discouraged unless it's on a bridged configuration which isn't going to happen with those speakers.
Will it work? Probably but under high volumes, you will eventually blow a Rectifier, being that is an amp from 2004 and used is that something you want to risk?
 
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dancerehab

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  1. You should add Speakers in sets preferable at the same ohm loads.
  2. Odd numbers are discouraged unless it's on a bridged configuration which isn't going to happen with those speakers.
Will it work? Probably but under high volumes, you will eventually blow a Rectifier, being that is an amp from 2004 and used is that something you want to risk?
Thank you Delaro. I figured that it would be safer to just pair the same speakers on the same channel 'sides'. You mentioned that this is an amp from 2004, well in regards to sound is it that bad of an option?
I tested the three speakers btw and when they are all on i get a a slight rattling noise on the tweeters, 'sounds like a radio connected directly to a small solar panel on a cloudy day' After troubleshooting i discovered that my pc's power supply cannot handle that much current, funny enough when i disconnect two speakers the remaining speaker works well , but when playing a good beat i can see slight dimming on the power light. I think I will leave it at the one speaker and use my bookshelfs for a few more days on the smaller amp as i look for a more powerful power supply, probably 20+ amps.
 

delaro

Splendid
Herald
PC supplies are not designed for Audio use, you will likely always have noise to deal with. A test bench amp and a 4700 uF Capacitor would be more ideal since it will eliminate any possible noise but that is going to run you $40+ for a 5 Amp.

Another Lepai and a balanced load would be more ideal, this actually sounds quite nice together for the cheap price.
Dayton Audio B652 + Lepai LP-2020TI $49

You could substitute the 2X 2020's for a Lepai LP-269FS $40 since it's a 4 channel if you want less clutter but you will sacrifice some sound quality in the process.
 

dancerehab

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Noted, when i look at my options i still have to consider tax and shipping cost because i am not in USA, that alone makes the budget quite a lot. Getting one of this locally is cheaper compared to the other options. My worry is if i get a 12v 30Amp power supply can it fry the amp or? I know the amp is normally used with car batteries hence high current needed.I just need to be sure.
 
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delaro

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Herald
You only need the rated amount of Amps, having more is irrelevant. Think of Amperage as the pull, a device will pull what it needs. Voltage, on the other hand, is the push, whatever is present the device will take until it faults out.
 

dancerehab

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You only need the rated amount of Amps, having more is irrelevant. Think of Amperage as the pull, a device will pull what it needs. Voltage, on the other hand, is the push, whatever is present the device will take until it faults out.
Okay thank you, but my issue is with the pc power supply that does 12v 8amps at the moment is not enough to run the amp. when playing music and i look at the power led i can see it's dimming slightly. not stable at all. also the sound starts to have a slight clip when i introduce three speakers all playing at an average volume. This is a car amplifier and a car battery is normally rated 30+amps, that's why i knew i have to have the right amount of current, or what do you think?
 

delaro

Splendid
Herald
Well in a Car your running of the Alternator most of the time so your getting between 13.5 to 14.7 Volts and a 2A buffer. Car amps are rated higher than 12V typically around 14.4V even though they may list 12V.

A pc supply is precise with Voltage it has a metered 12V +/- 5%, it's possible to modify them to 14V but the how depends on the Class "AB or D"

Switching supplies you are going to run into the same situation, you need to make sure you have the option to adjust the voltage so you're not limited to 12V.

Either a PC supply or Switching should be running at 80% or less load so for a 300W Amp you want a 400W supply or larger, either of these will struggle under heavy bass because of the lack in voltage on a 12V limit but they can work.

AC/DC converters- could work as well but they get expensive fast.

Test bench supplies start at 13.5V for the cheap Pyramid models and the better versions are fully adjustable.

Are you seeing why I recommend a Home amp yet, it's just less of a hassle.

Where do you live by the way? When you get into audio it sometimes is easier to find things outside the US since there is a larger DIY community for it.
 

dancerehab

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Apr 10, 2018
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Well in a Car your running of the Alternator most of the time so your getting between 13.5 to 14.7 Volts and a 2A buffer. Car amps are rated higher than 12V typically around 14.4V even though they may list 12V.

A pc supply is precise with Voltage it has a metered 12V +/- 5%, it's possible to modify them to 14V but the how depends on the Class "AB or D"

Switching supplies you are going to run into the same situation, you need to make sure you have the option to adjust the voltage so you're not limited to 12V.

Either a PC supply or Switching should be running at 80% or less load so for a 300W Amp you want a 400W supply or larger, either of these will struggle under heavy bass because of the lack in voltage on a 12V limit but they can work.

AC/DC converters- could work as well but they get expensive fast.

Test bench supplies start at 13.5V for the cheap Pyramid models and the better versions are fully adjustable.

Are you seeing why I recommend a Home amp yet, it's just less of a hassle.

Where do you live by the way? When you get into audio it sometimes is easier to find things outside the US since there is a larger DIY community for it.
I get it, all the voltage hustle and all. Damn true a home amp is more worth it to be honest. So i am guessing a switching power supply set to around 13/14 volts 20+amps should work right?I am in Nairobi kenya. In general my conclusion is that a decent DIY audio system can be quite expensive depending on what a user hopes to achieve.
 

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