Yamaha A-s801 impedance

[Testpoint Jerry]

Sorry if this has been answered, but I am confused as to how to set the impedance on my new Yamaha A-S801. I will be using 2 sets of floorstanding speakers, one JBL and one Athena Technologies. Both are fairly efficient.

The Audioholics review says "NEVER touch impedance switch, leave it on 8 ohm high setting"

I get the reasoning, and not starving the amp of usable power, but here is my confusion. The amp does not say 8 ohm for high setting. It is defined as follows:

Low- A or B 4 OHM EACH
A And B 8 OHM EACH

High- A or B 6 OHM EACH
A AND B 16 OHM EACH

Note: The Yamaha runs the A and B speakers in parallel, So I will effectively have a 4 ohm load.

So which do I choose to safely listen to both sets of speakers at upper moderate levels. Not earsplitting, but driving fairly.

Thanks for any advice!!

-Jerry

 

[j_garcia]

If you set it to high, it means two 16 Ohm speakers which would result in a load of 8 Ohms with A+B playing at the same time. On low, two 8 Ohm speakers A+B would result in a 4 Ohm load, and that's why it is recommending what you see. So it looks like you would need to use LOW.

 

[Testpoint Jerry]

That is the Mfg. recommendation, as it is on all amps, however the Audioholics review of this amp say to leave on high even for 4 amp load??????

From Audioholics:

The A-S801 has a detachable two-prong power cord that is convenient for installation purposes and for audiophiles that pray to their cables and want to use esoteric alternatives as expensive tone controls. You see that impedance selector switch on the backpanel? Don't touch it! Leave it at its factory default ‘high’ setting regardless of the speakers you connect, or else you will be starving your speakers of power just to validate a UL heat dissipation test that is required to list 4-ohm capability on the silkscreen.

Do NOT change the impedance switch from it's default setting.
The A-S801 utilizes high quality gold-plated RCA line level connections and 5-way speaker binding posts. You can connect two pairs of speakers to the A-S801 and they are wired in parallel to avoid the sonic degradation that happens when you connect two pairs of speakers in series. Just be warned if you do connect two pairs of speakers and use them at the same time to make sure they are 8-ohm nominal impedance, since the amplifier will see the parallel equivalent load of 4 ohms in this scenario.

So I'm still confused......

 

[j_garcia]

Hmmmm.... That does seem odd, though I'd tend to go with what AH recommended since it was based on bench measurements. Though this unit is clearly 4 Ohm stable, I wouldn't run it in low impedance mode with two sets of speakers simultaneously.

From the measurements section:

There is a dreaded impedance switch on the back of the A-S801 that reduces the output power of this unit for certification purposes only. We recommend leaving it at the default 8 ohm setting and NEVER changing it.

 

[Testpoint Jerry]

Yes I'm perplexed. Never changing it whether you use 4 ohm or 8 ohm speakers would mean they recommend using the high setting (factory default) with a 4 ohm load, as they state in the full review. Effectively 2 sets of 8 ohm speakers in parallel is the 4 ohm load. Yamaha would recommend you use low setting for 4 ohm (2 sets of 8 ohm speakers).

Who to believe..........

 

[PENG]

Yes I'm perplexed. Never changing it whether you use 4 ohm or 8 ohm speakers would mean they recommend using the high setting (factory default) with a 4 ohm load, as they state in the full review. Effectively 2 sets of 8 ohm speakers in parallel is the 4 ohm load. Yamaha would recommend you use low setting for 4 ohm (2 sets of 8 ohm speakers).

Who to believe..........

AH suggested to leave it in the 8 ohm setting even for 4 ohm speakers for performance reasons. Manufacturer has to tell you to use that switch most likely because of UL, CSA requirements. If you know when to turn down the volume, then you know the right answer to your question right?

 

[Testpoint Jerry]

OK PENG, So 2 sets of 8 ohm in parallel for a 4 ohm load total. Leave it in high position (Yamaha 6 ohm) for maximum performance as to not have the power output reduced. Just don't use at MAX volume and monitor for heat or shutdown. Since amp is basically 4 ohm stable all should be fine, correct??

 

[M Code]

Popular 16 Ohm loudspeakers are non-existent..
Leave it in the HIGH position, better dynamics..
Just make sure U have adequate free-air clearance of 4-5" for the unit's L/R sides and top cover. And don't stack anything on top.

Just my $0.02...

 

[PENG]

OK PENG, So 2 sets of 8 ohm in parallel for a 4 ohm load total. Leave it in high position (Yamaha 6 ohm) for maximum performance as to not have the power output reduced. Just don't use at MAX volume and monitor for heat or shutdown. Since amp is basically 4 ohm stable all should be fine, correct??

Most amps, such as the A-S801 can provide much higher dynamic output than their rated continuous output, to take care of the dynamics in music. It is sustained high current output into low impedance load that is the real concern. I am not sure if the A-S801 is "4 ohm stable" as such, also remember your 4 ohm speakers (2- 8 ohm speakers in parallel) may have impedance dips that could be well below their so called nominal impedance too.

If you want to play it safe, then you should use the low setting, but then it will limit the amp's dynamic capability resulting in poorer sound quality. If you leave it in the high setting, then you must exercise more care, "monitor" for heat, and any slight trace of audible distortion is definitely a good idea.

In addition, please also pay attention to M Code's post#8.

 

[Testpoint Jerry]

Thanks for the advice! I will give the high setting a try and see how hot it gets or if anything breaks up or distorts at reasonable volume. If so, then it's back to low.

As I mentioned the detailed review of this amp by the audioholics guys tells you to leave the switch high and never touch it no matter what impedance speakers you connect. I, however was a little more cautious at $953 I don't want to burn it up.

For the record I'm an Industrial electronic tech, audio is just not my line. Giant 3 phase ac inverter motor controls....no problem!

Cheers!

 

[PENG]

Thanks for the advice! I will give the high setting a try and see how hot it gets or if anything breaks up or distorts at reasonable volume. If so, then it's back to low.

As I mentioned the detailed review of this amp by the audioholics guys tells you to leave the switch high and never touch it no matter what impedance speakers you connect. I, however was a little more cautious at $953 I don't want to burn it up.

For the record I'm an Industrial electronic tech, audio is just not my line. Giant 3 phase ac inverter motor controls....no problem!
Cheers!

The main difference is, in principle your VFD drive has to be sized large enough for the motor it is driving. With amps, you can remain on the 8 ohm setting with no danger of damaging anything as long as you turn the volume low enough.

 

[Testpoint Jerry]

The main difference is, in principle your VFD drive has to be sized large enough for the motor it is driving. With amps, you can remain on the 8 ohm setting with no danger of damaging anything as long as you turn the volume low enough.

Excellent analogy. Thanks again for the advice. Amp is arriving today! Cheers!

 

[Testpoint Jerry]

Quick update for those that offered advice. Yamaha A-S801 Amp arrived. Left impedance in factory high position. Connected both sets of floor standing speakers. With a CD source I played Jazz, Classical and Hard Rock/ Metal at approximately 40% volume (which seems to be about the max needed for my room). The amp never flinched, not a whisper of distortion and cool as a breeze. Not even a little warm. It's on it's own shelf of my rack with full clearance. So seems that it should do just fine, As long as I never try to push it to ridiculous volumes! Sounds very clean and amazing as well.

Thanks again for the help!

 

[Obxdrew]

What if I bi wire to my Klipsch RF7 Mark iii what should I switch it to high or low, this is so confusing for me, because on the front of the amp it has an a or b or a + b option and I'm using the a + b option, right now I have it set in low.. any help would be appreciated thank you

 

[lovinthehd]

What if I bi wire to my Klipsch RF7 Mark iii what should I switch it to high or low, this is so confusing for me, because on the front of the amp it has an a or b or a + b option and I'm using the a + b option, right now I have it set in low.. any help would be appreciated thank you

There is no good reason to bi-wire generally. Why do you think it will be a benefit? Sounds like you're trying more to passive bi-amp, too. Neither is worthwhile IMO. Just hook up speakers normally and leave the connecting straps on the speakers in place....if you need more amp get a more powerful amp. IMHO.

 

[Obxdrew]

There is no good reason to bi-wire generally. Why do you think it will be a benefit? Sounds like you're trying more to passive bi-amp, too. Neither is worthwhile IMO. Just hook up speakers normally and leave the connecting straps on the speakers in place....if you need more amp get a more powerful amp. IMHO.

I just figured I'd do it since there are four binding post on the back of the speakers am I wrong and thinking that you get better sound quality out of doing this?

 

[lovinthehd]

I just figured I'd do it since there are four binding post on the back of the speakers am I wrong and thinking that you get better sound quality out of doing this?

Yes, you are. It's more a marketing thing than anything of real value. Many speaker designers have mentioned that they only include the dual posts due to marketing pressure, not a need. There can be a slight electrical advantage but not likely an audible one

 

[Obxdrew]

Okay well I just connected the standard red and black to the back of the speakers and put the binding posts connectors back on switching it to a and high impedance we'll see

 

[lovinthehd]

Okay well I just connected the standard red and black to the back of the speakers and put the binding posts connectors back on switching it to a and high impedance we'll see

I'd just generally recommend finding good stuff to listen to....and the quality of that will vary, too.

 

[Obxdrew]

I try lol, I subscribe to Tidal HiFi and stream through a bluesound node 2i via coax to my 801. This is a whole new world for me