Posted by: delakova

PRE-AMP VOLTAGE - 04/02/17 11:18 PM

I hope someone can shed some light into my issue. I just purchased a 7200 It is practically new very few hours not a sratch. Now from what I understand the input sensitivity is 1.433 volts minimum. My Onkyo Tx nr 707 has the pre- outs at 1 volt so I connected the amp and I find no difference in amplification. I understand that the speakers the room how far I am from the speakers all that taken into cosideration. But sonically I hear no difference. Is my Onkyo Hindering the performance of the 7200? Also I want to ask another question I was told that I needed a power conditioner like a 20 amps minimum for that amp but I find them very expensive. Some people swear by them others just say is a waste of mobey any thoughts?
By the way here is my set up
10x20 room 15 foot ceiling room is open in the back for the dinning and the right side to the kitchen
Martin Logan Motion 35 x
Martin Logan motion 8 front
Martin logan motion 4 surround
2 free channels
Oh and a Klipsch 10 inch sub w 150 continuous
Thinking of getting a HSU research 12 the newest one w front firing driver and two ports adjustable but we will see I just want to solve this issue first
I thank you in advance
Posted by: XenonMan

Re: PRE-AMP VOLTAGE - 04/03/17 06:16 PM

I couldn't find specs on the TX-NR707 but the SR707 has a power output rating of 100 wpc. I am sure that rating is based on 1 or 2 channels driven and goes down as more channels start using power. The 7200 will put out 300 watts to every channel if pushed to the wall with an input of 1.43 volts from the processor. Since the processor is only capable of outputting 1 volt the amp is not getting all the signal it needs to provide the rated output. I would guess that since your are providing a little more than 2/3 of the needed input you are getting about 2/3 of the rated output. I would estimate that the 7200 is putting out about 200 wpc into 4 ohms. That extra power will only result in a 3 db improvement in sound pressure level at best. Your speakers appear to be 4 ohm impedance so they are a bit harder to drive but will present no issue for the 7200 with the full input voltage. What you do gain from the 7200 is headroom. Also by feeding the 7200 only 2/3 of its rated input I would expect you will never have that amp clip at any volume level even though you may not notice a big increase in available spl.

As far as a power conditioner, you will need one capable of providing about 2000 watts of power which is what the amp could POSSIBLY draw in worst case. is highly unlikely you will ever push that amp anywhere near its limits. The power supply in the amp does not need conditioning unless you live in an area where the voltage sags or peaks frequently. What you really need is a good surge suppressor so lightning or other grid failures don't take out your expensive gear. I use power conditioners to provide superb suppression but there are many good suppressors available that don't cost a lot and provide a lot of protection. If you get one make sure it gives you some type of warning when it is no longer capable of surge protection. Some turn on a light but the best ones just prevent power output if the device can't do it's job protecting you stuff.
Posted by: delakova

Re: PRE-AMP VOLTAGE - 04/03/17 10:02 PM

I thank you for the quick reply and the great knowledge . Do you think something like a power surge protector from Furman is good enough or a Panamax ? Also one last question does the brightness in sound come from the pre or the amp? I find it a little too bright but maybe my room. It may need treatment. Thanks again for your great input
Posted by: EEman

Re: PRE-AMP VOLTAGE - 04/04/17 12:33 PM

I have a Tripplite (LCR2400 I think) and have never had a problem.

Outlaw sells the SurgeX. I have no experience with those models though so I can't comment.
Posted by: XenonMan

Re: PRE-AMP VOLTAGE - 04/04/17 01:32 PM

Furman, Panamax, Tripplite and APC all good stuff. Assuming the system isn't using some enhancements (in the processor) to the audio such as treble boost or some sort of equalizer, the brightness is likely due to your room conditions. You can hang stuff on the walls to reduce the frequency bounce somewhat. The fact that the room is large and opens into another room is part of the problem. I doubt your speakers are making the sound brighter and although many people say they can hear big differences in amp sound I don't think that is your issue either.