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speaker matching for pioneer a-66x.

R

robinjhorn

New Member
Hi everybody,

I,m looking for some help and advice with an amp I've just bought for my workshop. After a little trouble finding the right type of amp (and buying one wrong one already...) I've gone for a Pioneer A-66x, an "ok" late 80's amp which I suspect will be good enough quality and power for a large noisy workshop. It's rated at 80w per channel into 8ohms and crucially has two speaker channels that I intend to use (needing both channels was my problem with finding a suitable amp for a low price.)

The problem I'm having is that I've currently already got a set of Mordaunt Short Ms10i's and some Leak 2060's that i was wanting to use in the small and big space respectively. Having bought the amp though I've now discovered that the channels are rated on the back of the unit as follows:

A: 6-16ohms / speaker
B: " " "
A+B: 12 -32ohms / speaker

Here's Hifi-engines specs: http://www.hifiengine.com/manual_library/pioneer/a-66x.shtml


With the MS10i's and the Leak 2060's both being rated at 8ohms and15-60w and 50w respectively I'm concerned as to what the repercussions are and how im interpreting the channel ratings...


In my head the A+B channel rating suggests I need at least 12ohm speakers on each channel and ideally 80w or higher max input. Is this right?

Now I'm not massively concerned about the wattage as I doubt we'll be going much past halfway on the volume. We only want enough to hear the music not to have our faces melted.

but I am concerned about overworking the amp and damaging it (or the speakers for that matter) with this setup.

I understand that this is fairly basic stuff and have made some efforts to check my reasoning but at the moment I'm hellishly busy and am resorting to asking for help from the community as I really have no spare time at all!


Any advice would be much appreciated, I'd like to use the speakers I already have as I cant justify buying more on the business expenses but if this amp is a terrible idea for them (or vice versa) then I may well sell it on and buy another...

One option i thought of was to get an extra two pairs of cheapo skeapers to wre up to each channel in series to up the resistance? Would this work if necessary?

Cheers,

R.
 
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Yes, wiring the speakers in series would work, but might not sound ideal, and they may not play at the same loudness.

You say "and buying one wrong one already". What was wrong with the first amp? Do you still have it? If so, my choice would be to use one amp for each pair of speakers. Assuming you don't plan on using the tape inputs, you can run the "Tape 1 REC" jacks on the Pioneer to any input except phono on the other amp using a stereo RCA cable, and whatever you select on the Pioneer will also be selected on the other amp. This will give you independent volume control of each speaker pair. The only disadvantage of this scenario is that the volume of each pair of speakers will be totally separate - that is, if you turn the volume down on one you'll have to turn it down on the other. There may be a way around this if you tell us what type of amp the other one is (if it has preamp outputs then you can wire them together and have one volume knob control both amps).
 
Hi swechsler,

Thanks for the reply, The first amp was a cheaper marantz, pm4400 i think, but was quite scruffy, sounded pretty bad and didnt seem to be working properly, hence, the wrong one.
I'd really like to be able to use both channels (as opposed to one channel and the two speaker pairs wired in series) so that I can choose to turn off ether zone if necessary.

Ideally I'd like to know if using the Ms10's on channel A and the Leaks on Channel B at the same time will overwork the amp if its only set to about half volume. I know that one channel at a time would be fine but both might be pushing the amp/speakers a bit too much.

I was thinking that -really as a last resort - i could hook up some cheaper speakers after the Leak's and the MS's to increase the impedance on each channel for when I'm running both simultaneously and hopefuly not worry about the second set sounding sub par.

What do you think about the standard setup? does it seem too risky to you?


thanks,
R.
 
Yes, you will in theory be overloading the amp relative to the manufacturer's specifications. Check the manual first. If it says it incorporates protection circuity (for the amp) then I'd go ahead and try it. Otherwise I'd monitor the amp to see if it gets too hot while running the two pairs of speakers in parallel at your preferred level (start at a reduced level and slowly increase the volume over the course of an hour or so). If it stays cool then you're good to go. If it doesn't then you'll need to use a second amp. Saying "set to about half volume" is meaningless because amps have different volume controls and speakers have different sensitivities, so half volume on one amp/speaker combo will probably not be the same volume as a different combo. Luckily, in most listening situations you're using only a fraction of a watt even when you have the system turned up fairly loud, so you'll probably be OK.

One caveat: I notice that the Leaks are fairly old, acoustic suspension, while the Mordaunt Shorts are considerably newer and ported. The latter may end up being a lot more sensitive than the former, you may not be happy with the difference in levels of the two different pairs.
 
Based on what is on the back panel, this amp places the two sets of speakers in parallel, so that two pairs of 8 ohm speakers presents a 4 ohm load to the amp, which it apparently is not rated to handle very well. Looks like it could take 6 ohms (i.e. two 12 ohm speakers in parallel). Now it may be OK as suggested above, so you can try it.

The other thing you could do is get an impedance compensating speaker selector box. Connect your amp to the inputs and the two sets of speakers to the outputs. Regardless of whether you have one pair or both running, it maintains an 8 ohm load on the amp using internal autotransformers. Look up "impedance compensating speaker selector". Russound is a popular brand and there are others.
 
Thanks for the advice, I figured I'd keep the amp and try it with these speakers, as you say going gingerly volume wise to see how it copes for heat. I'll have a look at the manual for the protection circuitry too, good tip!

I'm definitely a little skeptical about the different era of speakers but my budget dictates not buying new ones at this stage and also not if they sound okay. They'll also be in very different sized rooms so balance between the two pairs might be beneficial even.

I'm gonna take my leaks in tomorrow and give them a try too. I'll let you know how I get on, and once again, thanks for the tips. :-)
 
Nothing wrong with speakers from different eras, they are all basically just loudspeakers and there are good ones and bad ones from every era. Let us know how it turns out.
 
I think that amp should be able to run 2 8ohm speakers A+B. Especially if at moderate levels. One set will probably be louder than the other because they are different, may not be real noticeable though. If this is an issue, figure out which is the dominate set and then maybe move around.
 
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