QuestionQUESTION: I've recently bought an amplifier and other hifi separates, and it's my first time buying a 'proper' system. I'm a bit confused by certain things. I've a Marantz PM6002 amplifier. This is the details of it in my user guide:
RMS power output: 45w x2 [8 ohm load]
60w x2 [4 ohm load]
Power consumption: [4 ohm, 45w x2 output] 250w
I bought a pair on Monitor Audio Bronze speakers with 100w power and an impedance of 6. That was before I knew the importance of impedance. Everything is working ok, despite the Marantz amp having am impedance guide of 8. But I'm wondering how much this amp could take. I'm buying a subwoofer, which has an amp of its own, so I've been told that makes no difference to how hard my amp will have to work.
I was looking at maybe buying a centre speaker and another speaker, which would make 4 speakers and a subwoofer. But I just want to know how I can safely do it.
From what I've read, my two speakers at 6 ohms are in reality half that when together? So if I buy two more light speakers at 8 ohms, would my amp be safe as long as it was wired the correct way? I've read that it can be wired in such a way as to increase the impedance...but haven't looked at it in detail.
My subwoofer will be a powerful 275w and my speakers, as I've said, are 100w at 6ohms, so if I bought a couple of speakers at maybe 60-80w at 8ohms and wired everything right, should my amp be ok?
I've a bit of learning to do on this.
Thanks.
ANSWER: Hi Paul.
Your amp is a two channel amp so it will not 'do surround' with only two channels. Surround Sound is actually much more than just a few decent speakers placed around you.
To answer the main concern, your amp is FINE with a 6 ohm load per channel (a range of 4 to 8 Ohms is allowable).
As to the wattage they are currently receiving:
6 Ohms is between 4 and 8 so your power (to each channel) at 6 Ohms is about 52.5 watts RMS. If you actually could supply both speakers with 100 watts you will not get them much louder than 52 watts will.
Doubling the power only gives you +3 Db of gain. Doubling the amount of speakers usually yields a +6 Db gain.
IF you bought 2 more identical speakers at 6 Ohms each and wired them in parallel (each speakers' pair of wires going directly to the same channel outputs on the amp) you would only have a 3 Ohm load per channel. *When wiring more than two speakers (of different impedance) in parallel the total impedance load on the amp is 'reciprocal' and more difficult to solve in the design stages than 2 speakers of the same impedance.
Of course, you can NOT wire in the 6 and 8 ohm speakers parallel either or your amp may overheat become a paperweight (load would be about 3.43 Ohms)!!
Wiring the speakers to increase the impedance (series wiring) would give you 14 Ohms (6 + 8) which is no good either. Series wiring is easy to solve in your head.. just add them up.
Impedance calculator:
http://colomar.com/Shavano/impedance_proc.php
Be sure your impedance 'load' is within the amps' specified range (per channel) and you will be 'safe'.
If you want to get into Home Theater, you really need a multi-channel HT Receiver or HT amplifer. Then you will have the tools needed to sort it out proper when you set it all up. Many options for room size and delay times for each speaker ect are needed to do HT properly. Reputable HT components have them.
Suggested reading on HT receivers:
http://www.crutchfield.com/learn/learningcenter/home/receivers.html
Additional reading (FAQ) about home speaker wiring ect:
http://www.crutchfield.com/learn/learningcenter/home/receivers_faq.html
Help on basic impedance:
http://www.harmony-central.com/articles/tips/speaker_impedance/
You have the desire, now you need to exercise patience and do some of the basic learning! The dividends can be remarkable in getting what you want/need the 1st time while leaving pertinent options available for future upgrades without scraping the entire system.
I hope this helps. I do not want to overwhelm you. Get through the meat of theose links and please let me know if I can be of further assistance.
JM
---------- FOLLOW-UP ----------
QUESTION: Ok, thanks for the answer/info. I've only just bought the amp, so I guess I'll stick with it for a while. The sound quality is certainly a big step up from what I've had before, and I haven't even got the subwoofer yet, so I can't complain too much.
What do you think my best options would be once I get the subwoofer, in your opinion?
AnswerOh yes, the setup you have should drive nails as is (for what it is)!
I always prefer a straight-forward, front loaded stereo system (with a sub if it needs one). When you add a sub it is referred to as a 2.1 system.
I have never found a 5.1 or 7.1 HT system that made me really feel like I was outside a hanger next to a jet taxiing or passing by ect.
Dolby 5.1 or 7.1 HT is neat and IS different sounding than a conventional 2.1 stereo system but the jury it still not buying it as it being anything close to perfect yet. Center Channels can be an effective way to make most of the dialog appear to come from the screen, but I would rather it be in two channel stereo. I prefer the imaging and staging of the simple and time tested 2.0 or 2.1 stereo system (realizing I may be out of luck when it comes to hearing Dolby 5.1 and 7.1 encoded movies to some electronic engineers' idea of 'correct').
This means that in my opinion, if the speakers and sub sound good to you, you are done!
If you have trouble setting it up, understand that you will likely need to do a bit of tweaking to the location of the speakers and the sub as well as setting the relative volume levels between the two before it will sound best to you.
Tune the system to its weakest link (depending on which sub/amp combo you choose, the weakest link will probably be the two stereo speakers' limit). One mark of 'good speakers' is a pair which sound very similar no matter where you place the pair. Your set may be this way, but as you listen for an extended time with various material, you will probably notice the subtle changes when you move them.
For now I would go with the sub give it some auditioning and time then see how that goes.
If you want to get into Home Theater 5.1 or 7.1 there are many solutions available but unless you want to buy all component amps (durable, costly, very flexible, but not very simple), it would be easiest and probably best for a novice to get an all-in-one, 5 or 7-channel HT receiver.
See those attached links for more on that.
Save the Marantz for the study :)
JM
