2. amps-preamps
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need help with impedance on SF power 2

I just get a Sonic Frontier power 2 and Genesis APM-1. On the manu, APM-1 impedance is 4 ohms and I am not sure what is the normal impedance for power 2. Is all SF power amp @ 8 ohms. I read on the manu said I have to make sure impedance match with speaker. What effect if I have 8 ohms on the amp and 4 ohms on the speaker? I felt like I need to turn up the volume quite high in order to get a good sound level. BTW, the APM-1 is 90db sensitivity.
waip7
waip7 OP
11 posts
 
Thank you, Gsselling & Kana813. The power 2 I got is actually SE version, they use the kt88. If I put it on 8 omh tap, will it shorten the life of the tube?
kana813
956 posts
 
You are very luckly to get an SE.

Using the 8 ohm tap will not shorten tube life.

Just make sure the tube bias is set correctly, which is very easy to do on SF amps.

If you decide you don't like the amp, please contact me.
waip7 OP
11 posts
 
I set up every thing today and put the power 2 into 8 phms tap. I also have a line 2 pre amp. However, I felt that i need to turn the volume up to 60-70 (line 2 volume control from 0-95) in order to get a enough volume level. I check the bias and it is right. Did I do some thing wrong? The APM-1 is a 5way speaker. It has its own amp for the 15" woofer. So, the power 2 just need to push two 6", one 5" and two 1". It should not need to push that hard. I am using the trivista as the source. Since the trivista doesn't have the xlr output. I put the RCA to line 2 and from line2 to power2 using the xlr. Will that cause any trouble?
kana813
956 posts
 
Waip7- I also have a SF Line 2, running a single-ended/RCA
source in and balanced XLR out to the amp is perfectly
fine.

A volume level between 60-70 for loud normal playback
is also fine. I normally listen between 55-65, but my amp's
input sensitivity is lower than the Power 2. It also depends on the output level of the source and the size of your room.
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