Speakers and amplifiers! please help

[altuss]

So I've been wanting to hook up my record player to some external speakers as the internally built ones are burning out. I've done a load of research on the topic but there are some gaps in my knowledge still.

I've bought an amp, an old one i believe, after understanding I must hook up my turntable to the phono inputs of my amp. The amp is a Fisher Studio Standard CA-30R. It says 120w on the back, with 2 channels at 8ohms. Bare in mind i did not receive a manual with this second hand purchase and I can find almost nothing on the product online.

From this information, my research tells me the amp can handle two 40w speakers at an 8ohm load (one per channel). Is this correct?

Also, above the outputs of my amp is where the "8ohms" is located. Now does this mean each channel (im assuming channel means one output for one speaker, say the left one for example) takes 8ohm loads, or 4 each distributed through both channels?

Once i have all of this worked out, I'd like to also use this set up so that my PC is the input, rather than the turnable, and be able to switch between the two. From my understanding, I'm able to just use a universal 3.5 jack to rca cable so that I can lead the output from the green socket in my PC to the phono input of the amp. Is this correct?

Thank you for your time, buying this amp with no information as a complete newbie to this field of interest was real tough.

 

[delaro]

That Amp is actually a 2X70 watt @ 8ohm minimum So the output of each speaker max is 35watts. Typically home speakers are 8, 12 or 16 ohm while Car amplifiers use 4 ohm.

Here is something you should know about House setups. The ohm rating on an amplifier is actually a current rating but instead of being expressed in amps it's expressed in "minimum ohm" to make it easier for you to understand the information. You can use any speaker rated 8 ohms or above on your amplifier.

The difference is that you can get as much as a 50% power reduction. For example, 2.83 volts across 8 ohms produces 1 watt. The same 2.83 volts across 16 ohms produces 1/2 watt. Due to the lighter loading the amplifier will be able to put a slightly higher voltage into the 16 ohm load so the actual loss will be somewhat less than 50%. Assuming the an 8 ohm speaker and a 16 ohm speaker have the same sensitivity rating the 16 ohm speaker will play - 3 dB softer than the 8 ohm. Speaker sensitivity varies dramatically however. Take an old Altec A7 "Voice of the Theatre" with 16 ohm drivers and it will play a good +10 dB louder than the typical 8 ohm home theater speaker. So don't worry about the slight loss in power, it takes a 10x power increase/decrease to seem like a double or half in volume. With 16 ohms your amplifier will run cooler and if anything, have a greater life expectancy than if it were powering 8 ohm speakers.

You shouldn't have a issue running a 3.5mm jack to RCA splitter, I use a USB to RCA adapter myself the sound quality is a little better and I have more control in the software over the output. This also allows me to switch on the fly over the 2 analog outputs and the USB.

 

[altuss]

Thank you for your swift response! So you're actually suggesting that I run 2 speakers of 35watt power each, with 16 ohm loads? However, choosing speakers that are 8ohm is okay too? Also, how do you know my amp is 2x70 watt? Without sounding like I'm compromising your feedback, I'd like to be able to get to the point that I can look at an amp and understand its capabilities.

Just another question, though the max output is 35 watts with a minimum 8ohm load, would I be able to use 40 watt speakers at 8ohm? or do they have to be 35 watt and/or below?

Brilliant! I really appreciate this, thank you also for the USB to RCA adapter recommendation too!

 

[altuss]

That Amp is actually a 2X70 watt @ 8ohm minimum So the output of each speaker max is 35watts. Typically home speakers are 8, 12 or 16 ohm while Car amplifiers use 4 ohm.

Here is something you should know about House setups. The ohm rating on an amplifier is actually a current rating but instead of being expressed in amps it's expressed in "minimum ohm" to make it easier for you to understand the information. You can use any speaker rated 8 ohms or above on your amplifier.

The difference is that you can get as much as a 50% power reduction. For example, 2.83 volts across 8 ohms produces 1 watt. The same 2.83 volts across 16 ohms produces 1/2 watt. Due to the lighter loading the amplifier will be able to put a slightly higher voltage into the 16 ohm load so the actual loss will be somewhat less than 50%. Assuming the an 8 ohm speaker and a 16 ohm speaker have the same sensitivity rating the 16 ohm speaker will play - 3 dB softer than the 8 ohm. Speaker sensitivity varies dramatically however. Take an old Altec A7 "Voice of the Theatre" with 16 ohm drivers and it will play a good +10 dB louder than the typical 8 ohm home theater speaker. So don't worry about the slight loss in power, it takes a 10x power increase/decrease to seem like a double or half in volume. With 16 ohms your amplifier will run cooler and if anything, have a greater life expectancy than if it were powering 8 ohm speakers.

You shouldn't have a issue running a 3.5mm jack to RCA splitter, I use a USB to RCA adapter myself the sound quality is a little better and I have more control in the software over the output. This also allows me to switch on the fly over the 2 analog outputs and the USB.

?

 

[Cristi72]

That Amp is actually a 2X70 watt @ 8ohm minimum So the output of each speaker max is 35watts. Typically home speakers are 8, 12 or 16 ohm while Car amplifiers use 4 ohm.

Here is something you should know about House setups. The ohm rating on an amplifier is actually a current rating but instead of being expressed in amps it's expressed in "minimum ohm" to make it easier for you to understand the information. You can use any speaker rated 8 ohms or above on your amplifier.

The difference is that you can get as much as a 50% power reduction. For example, 2.83 volts across 8 ohms produces 1 watt. The same 2.83 volts across 16 ohms produces 1/2 watt. Due to the lighter loading the amplifier will be able to put a slightly higher voltage into the 16 ohm load so the actual loss will be somewhat less than 50%. Assuming the an 8 ohm speaker and a 16 ohm speaker have the same sensitivity rating the 16 ohm speaker will play - 3 dB softer than the 8 ohm. Speaker sensitivity varies dramatically however. Take an old Altec A7 "Voice of the Theatre" with 16 ohm drivers and it will play a good +10 dB louder than the typical 8 ohm home theater speaker. So don't worry about the slight loss in power, it takes a 10x power increase/decrease to seem like a double or half in volume. With 16 ohms your amplifier will run cooler and if anything, have a greater life expectancy than if it were powering 8 ohm speakers.

You shouldn't have a issue running a 3.5mm jack to RCA splitter, I use a USB to RCA adapter myself the sound quality is a little better and I have more control in the software over the output. This also allows me to switch on the fly over the 2 analog outputs and the USB.

Are you really sure? Check again all your statements.

 

[delaro]

Thank you for your swift response! So you're actually suggesting that I run 2 speakers of 35watt power each, with 16 ohm loads? However, choosing speakers that are 8ohm is okay too? Also, how do you know my amp is 2x70 watt? Without sounding like I'm compromising your feedback, I'd like to be able to get to the point that I can look at an amp and understand its capabilities.

Just another question, though the max output is 35 watts with a minimum 8ohm load, would I be able to use 40 watt speakers at 8ohm? or do they have to be 35 watt and/or below?

Brilliant! I really appreciate this, thank you also for the USB to RCA adapter recommendation too!

I use to own one, you can find the specs listed on the Chinese version of Ebay there are a few for sale. So yes 2 8 ohm speakers rated at 35 Watts or less.

Are you really sure? Check again all your statements.

The more ohms, the less output from the amplifier. Conversely, the less ohms, the more output from the amplifier. Does that make more sense for you? Now to add to this a Good Quality pair of Studio Speakers 16 ohms or better using 1/2 the watts as a 8 ohms speaker will be louder.

 

[Cristi72]

The more ohms, the less output from the amplifier. Conversely, the less ohms, the more output from the amplifier. Does that make more sense for you? Now to add to this a Good Quality pair of Studio Speakers 16 ohms or better using 1/2 the watts as a 8 ohms speaker will be louder.

Not necessarily, especially because you just mentioned about the acoustic efficiency problem.

Anyway, the things which triggered my intervention are:

1 - For an amplifier rated at 70-watt / 8Ohms per channel, you will need at least a 70-watt / 8 Ohms rated speaker. In this specific case however, you are right (lucky? I hope not ) when saying a 35-watt speaker will do, because the CA-30R is rated at 20 W RMS per channel at 8 Ohm (max. 35W with 10% THD).

2 - The amperage is useful when designing the final stage, so it has no meaning for the final user. The output voltage on the other hand is much more important, giving, in conjunction with the speaker's impedance, vital indications about the audio power capability of the amplifier (and it's much easier to measure of course).

 

[americanaudiophile]

The 120 watt figure on the back is probably near the power cord and tells you how much power the unit will draw from the AC not how much it will put into your speakers. You should use speakers that are 6-8 ohms and have a minimum power rating of between 20 - 30 watts. The higher the efficiency of the speaker the louder it will play with less power so if you want high volumes this is important.
If you want to connect your PC you would connect it to any input (aux or tape) on the Fisher other than phono as this input has an additional circuit board that would not work with any other type of source.
Also if your turntable has build in speakers it is a record player not just a turntable. Does it have RCA outputs on the rear? Are they line level or phono level? That will determine which input you would use on the Fisher. If there are no RCA outs then you can use one of these:
http/www.crutchfield.com/p_142LOC80/Scosche-LOC80.html
connected to the speaker wiring inside the record player and connect it to any input other than the phono input. That is because that extra circuit board is already inside the record player.