KEF Q300 + Pioneer SP-BS22-LR + Yamaha A-S500 = Amp turning off below half power? Why?

most.fm

Member
Oct 28, 2021
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0
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Dear What Hi Fi'ers,

I've recently connected my old speakers (Pioneer SP-BS22-LR) and my new speakers (Kef Q300) to an Amp I thought would be enough (yamaha a-s500). I bought the amp used but in very good condition - i think, but I'm not an expert.

I connected the amp and the speakers and it all works fine up to about 30-40% power (depending on the music) but at some point the amp just turns off abruptly aftera while.

I checked the malual and here is what is says:
yamaha.PNG


Could anyone help me shed some light on what I'm doing wrong and or how to narrow down what's the exact issue?
Is it because the two speakers have different impedance (Pioneer is 6ohms and Kef are 8)?
Or is it because it doesn't have enough power? Or maybe it's something to do with the wires?

I'm a total noob, so if it's obvious please don't get frustrated!

Anyhow, thank you very much for any help and insight you can provide!

Most
 

RoA

Well-known member
Feb 11, 2021
340
187
570
It reads like the amplifiers protection circuit is activated.

It's likely because it gets too hot. Do you listen fairly loud when it cuts out?

Whilst 30 - 40% of total power doesn't seem much when turning the volume dial it is likely the amplifier volume pot is calibrated so that only small adjustments are needed for relatively large jumps in volume. The result can be that you reach max volume on the dial far earlier than it may would otherwise on a properly calibrated product which utilises more of the potentiometer (and which often results in better S/N figures).

Not ideal but common on analogue potentiometers.

Furthermore, it's likely the manufacturer specifies 8ohm minimum when connecting 2 pairs of speakers simultaneously. Few speakers meet that spec these days. Try operating with one pair only or upgrade to a product that is specified to drive several pairs at the same time with a lower ohm rating when doing so.

There is of course a possibility that something is wrong with product.
 
Last edited:

abacus

Well-known member
Sep 24, 2008
684
378
19,270
When you switch on speaker outputs A & B the speakers are connected in parallel, which means 2 8ohm speakers become 4ohms at the speaker terminals (2 4ohm speakers become 2ohms at the speaker terminals), so as mentioned above by connecting your 2 speakers (Which will lower the impedance at the speaker terminals) is probably outside of what your amp is designed to accept, so you will either need to keep the volume low or just use one set of speakers at a time.

Bill
 

most.fm

Member
Oct 28, 2021
2
0
20
Thanks a lot guys! Could you maybe recommend an amp that could handle this setup? Or is there any other workaround i could try to implement?

I'd love to keep the speakers as they are if possible. If not - would this AMP work if I connected two pairs of identical 8ohm speakers?
 
Thanks a lot guys! Could you maybe recommend an amp that could handle this setup? Or is there any other workaround i could try to implement?

I'd love to keep the speakers as they are if possible. If not - would this AMP work if I connected two pairs of identical 8ohm speakers?
It should but in practice most amplifiers are designed to run only one pair of speakers at a time. Are your second pair in a different room?
 

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