Am I Trading Watts or Caught in the Upgrade Cycle?

[estebanelequente]

Here is my situation.
I have a 7.2.4 Dolby atmos system. My front soundstage are all 4 Ohm Martin logan Speakers.
Before you tell me I am listening too loud, I know I am, but that is how I like my movies. I have noticed that when I whatch a particularly dynamic movie my front soundstage clipps. I have identified that it is likely clipping and not the speakers distorting because I purchased a 200WX2@8 anthem amp for my Mains (Martin Logan Theos) and the clipping stopped on them. I hoped that this would cure the clipping coming from Martin Logan Motion C2 Center since I thought I was removing the most power hungry speakers from the equation. however I am hearing the same thing only in the loudest portions of extremely dynamic movies (Bladerunner 2049, Godzilla vs Kong, Mad Max Fury Road etc.). The rest of my system consists of 8 ohm speakers with the exception of my Logan Center. I am maxed out on my current AVR the Denon X3700H which is rated at 105wX2 at 8 Ohms. However I can not find the all channels driven specs for 8 ohms much Less 4 ohms. I have a lead on an inexpensive older adcom 5 channel amp (GFA 6000) that is rated at 150w at 4 ohms all channels driven on the 3 channels. but only 60w at 8 Ohms for the other 2. Its about $250. My issue is what I am getting with the denon with 9 channels driven is a total unknown but I feel like If I even borrowed 3 channels of amplification I am removing enough stress from my AVR to avoid the clipping. But Will I? and am I just trading watts considering I wouldn't be stepping up substantially? If all things are equal the 5 channels driven rating at 8 ohms on the Denon is 100w based on ASR then 6 ohms jumps to 1% THD. But Im running 9 right now and 1 of those is a 4 ohm speaker. The 100w 8 ohm rating on the adcom is the same with lower distortion on the adcom, the transformer is much bigger and I have a known 4 ohm value at a much lower distortion and would imagine benefit from more current or better circuitry. But I don't know enough and a 200W X3 or X5@8ohm amp is outside of my budget at the moment. I may have the option to buy and try with very little risk since it is sold locally by a vintage stereo shop. But I am curious what the brilliant minds here have to say on the subject. Also does anyone have a clue what the input sensitivity is on the adcoms of that era? It isn't in the manual.

 

[antcollinet]

If you are driving the amp to clipping, that is most likely a voltage limit. In which case it is not a shared load limit - so even if you only drive one speaker at that level, you will still get clipping. You've simply hit the highest voltage that the output stage can deliver.

If this is the case, then your only solution is (significantly) more power for all channels, remembering a doubling of watts is only 3db.

 

[estebanelequente]

If you are driving the amp to clipping, that is most likely a voltage limit. In which case it is not a shared load limit - so even if you only drive one speaker at that level, you will still get clipping. You've simply hit the highest voltage that the output stage can deliver.

If this is the case, then your only solution is (significantly) more power for all channels, remembering a doubling of watts is only 3db.

I’ve never heard of that. Excuse my ignorance, I’m. Or challenging you, but if you could clarify. If I had only 3 speakers clipping and they were the speakers with the most difficult load and I’ve already eliminated clipping on 2 of them by upgrading my amp on those 2 how would I not eliminate clipping in the 3rd speaker by replacing it with an amp that is more stable on a 4ohm load. Not necessarily the adcom but let’s say something with similar wattage and current as my anthem? You are saying it is an all or nothing proposition even though I’m only offended by my center at this point? Also what if I ran a dedicated circuit to my media room or am I misunderstanding what you mean by voltage. I looked up voltage limit clipping really quick and most of what I saw was about car audio. I’m just now learning about power amps.

 

[antcollinet]

Sorry - I was answering why taking the two speakers off as loads from the AVR didn't help with the third. My statement that more power is needed for that one channel is of course answered if you replace the AVR amp channel with one of higher power, such as your anthem

 

[Webninja]

How do you know you are clipping? And what are you using to measure volume (how many db is your too loud)?

 

[estebanelequente]

How do you know you are clipping? And what are you using to measure volume (how many db is your too loud)?

I am 13.5ft away my room is 17x15 the peak I measured through a db meter on my phone was 95db it was loud but not too loud.

 

[estebanelequente]

Sorry - I was answering why taking the two speakers off as loads from the AVR didn't help with the third. My statement that more power is needed for that one channel is of course answered if you replace the AVR amp channel with one of higher power, such as your anthem

I found a steal on a sunfire cinema grand in great shape for $500 I think I’m going to pick it up. It does 400wx5 into 4 ohms. I’m debating passively biamping my mains with it and running my center with it then using the anthem for my rear right and left. Thoughts?

 

[izeek]

holler back after you biamp, please. id like to know what you thought of the results.

 

[estebanelequente]

I never ended up biamping them. The 400w from the sunfire was more than enough and they sound great on that amp. I did a lot of research and without exception I found that it would provide little to no benefit to me.