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Discussion Starter · #1 ·
Hello, would be awesome if someone could help me understand a couple of things about my set-up.

I have an amplifier, which is an old Sony F419R and speakers are Pure Acoustics Noble II F.

First off: the amp supposedly delivers 65w to each channel, and the speakers are supposedly 185W (RMS). Now, I have been reading and reading about what it means and how to pair amps and speakers, but it got me more confused than when I started. Long story short, do I need a more powerful amp to get more potential out of these speakers? (It says 185W RMS on the back of the speakers, on Pure Acoustics website it says "Power Output 185W" and a couple of other places it was written that it's 300W peak, 185W RMS. This was what confused me almost the most about these speakers)

Second: The amp has a thing called "Spontaneous Twin Drive", I know it's just a buzz phrase, but essentially there's A and B channels. My friend told me that it is used to drive two speaker set-ups in for example two different rooms. But I was thinking, since the amp does 65W to each channel, could I hook up A+B Left to Left speaker and A+B Right to Right speaker, so that 65W+65W goes to a 185W speaker, thus getting more out of it?

Third: That A+B mumbo jumbo leads me to this - the speakers supposedly have bi-wiring and was wondering if I can use that to do the A+B. This part is the actual part that confuses me the most. Recently, I lost both bi-wiring links on one of my speakers, and didn't know that they were necessary for the speakers to function properly, so I connected the positive and negative to the top pair of connectors and noticed that the speaker did not play any low freqs and the highs were kinda silent. Figured out, that they were necessary so I connected the two pairs with a wire and it works fine now. I have a vague understanding of how crossovers work and why are they needed, but what I don't get is if the speakers have crossovers inside of them (I assumed that, since one signal with all the frequencies goes into the speaker and it works correctly) why the two pairs of connectors? Anyway, is it going to change anything if I connect A+B from amp to the speakers two pairs? Or could it potentially damage something?

Fourth: I noticed, that when I turn the volume knob somewhere over half (I'm assuming somewhat 30W to each speaker of power, since the amp does 65W to each channel) the sound gets distorted. Cannot really describe how does it sound, but it doesn't do clicky noises (read about overpowered speakers hitting the backplate, or something like that). I'm assuming it's because it's underpowered? Or is the amplifier worn-out to produce such loud sounds? Or could the speakers be damaged or worn-out?

P.S. The amplifier is 1992, the speakers - I don't know how old, but aren't too young too. They were used before I got them, of course :D

Thank You in advance! :)
 

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1. Many people overestimate their power needs. Your speakers have an above average sensitivity, and so 65 watts is more than enough power to make your ears hurt. It only takes 1 watt to produce their 92dB sensitivity at 1 meter away. 2 watts gives you 95dB, and so on. You lose SPL by moving away from the speaker, but will gain some from the room.

2./3. I would not bother bi-amping, there isn't a benefit unless you do active bi-amping, but this requires speaker modification and external crossovers.

4. Knowing this, you may want to look at a new amp. If you are hearing distortion at 50% volume, then this is your amp running out of steam. As power output goes up, so does THD (distortion). You want to keep the amp operating at an appropriate level, and pushing it too hard will cause the amp to clip which can damage your speakers.

That looks to be an old entry-level stereo receiver. You can get something now from Yamaha that will put out an honest 80 watts or more and give you more headroom. Check out www.accessories4less.com for some good deals on refurbished units.
 

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Discussion Starter · #3 ·
Thank You for Your reply!

There isn't a real need to "bi-amp" the speakers, 1/3 volume is loud enough, even at small parties :D Curiosity sparked my question. Good to hear that the most probable cause of the distortion is the amp, because I was beginning to afraid that the speakers are going. Another thing I'm a little bit afraid of is that I read that underpowering the speakers can and may damage them. Should I be afraid of this using my current setup?
 

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Thank You for Your reply!

There isn't a real need to "bi-amp" the speakers, 1/3 volume is loud enough, even at small parties :D Curiosity sparked my question. Good to hear that the most probable cause of the distortion is the amp, because I was beginning to afraid that the speakers are going. Another thing I'm a little bit afraid of is that I read that underpowering the speakers can and may damage them. Should I be afraid of this using my current setup?
You can't damage speakers by providing a small amount of power, you can send 1 watt via a small T-amp and they will play fine.

What this refers to is clipping. When you push an amp too hard, it will clip the signal and this can cause damage to your speakers. The important thing is to operate your amplifier within it's means, if you find yourself needing more volume, then you need more power or you can risk clipping. Based on your listening habits, this will not be an issue for you. But if you find yourself wanting it louder, I would recommend a new amplifier/receiver.
 
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Third: That A+B mumbo jumbo leads me to this - the speakers supposedly have bi-wiring and was wondering if I can use that to do the A+B. This part is the actual part that confuses me the most. Recently, I lost both bi-wiring links on one of my speakers, and didn't know that they were necessary for the speakers to function properly, so I connected the positive and negative to the top pair of connectors and noticed that the speaker did not play any low freqs and the highs were kinda silent. Figured out, that they were necessary so I connected the two pairs with a wire and it works fine now. I have a vague understanding of how crossovers work and why are they needed, but what I don't get is if the speakers have crossovers inside of them (I assumed that, since one signal with all the frequencies goes into the speaker and it works correctly) why the two pairs of connectors? Anyway, is it going to change anything if I connect A+B from amp to the speakers two pairs? Or could it potentially damage something?

Thank You in advance! :)
If you are missing the jumpers for the speakers - then cut some small wire and use it
to connect the lower inputs to the upper inputs > black to black, and red to red - then
connect your speakers from the receiver with wire to the upper or lower section only.
I would not use both the A and B speaker inputs on your receiver.

http://i782.photobucket.com/albums/yy109/postcards_2010/P1150766.jpg
 
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