• New Patreon Tier and Early Access Content available. If you would like to support AVForums, we now have a new Patreon Tier which gives you access to selected news, reviews and articles before they are available to the public. Read more.

high level input blown?

Tone DeFeet

Active Member
Hi sub fans, I was wanting to add a few extra low Hz to my setup (sig) so blew the dust off my long retired acoustic solutions av sub which had been living in the loft for a few years, but it seems to have developed a fault. As soon as I touch a + speaker wire to the high level inputs it rumbles like hell "PFRRRRRRRRRRR" (even with the amp off ??). The low level input works fine from my ipod but my amp doesn't have a low level out so I need to use high. Does this sound terminal?

Also while I'm here - I don't want to add to the speaker impedance as I'm already running 2x8Ω speakers per channel. Am I right in thinking that adding a sub at high level input isn't pulling extra from the amp as it is just using the speaker outs as reference only and amplifies it's own signal?
 

Nimby

Distinguished Member
If it's an active sub with its own amplifier, then no, it doesn't draw power.

You are going to have to explain the 2 speakers per channel.

Just because a speaker says 8 Ohms doesn't mean it is 8 Ohms at all frequencies. The impedance often drops dramatically at some point in the response.

Playing loud could be very hard work for the amp into only a couple of Ohms. Check the amp's external heatsinks, if any, after a listening session.
 

Tone DeFeet

Active Member
Thanks for reassuring me about the active sub question.

Essentially I've got the evo 3's as my fronts and the castles as rears although they are both driven by my stereo amp. My amp is rated for 4-8Ω so (from what I've read anyway) it can comfortably accommodate a pair of 8Ω speakers per side (8Ω+8Ω=4Ω) and besides I hardly ever crank the dial past 9 o'clock. My concern was that by adding the sub I'd be pushing the amp just a wee bit too far.
 

Nimby

Distinguished Member
I'd say your amp is at risk from the speakers unless you do keep levels down.

If you really want to get the most from your system while staying with your stereo amp then try and find a used Yamaha DSP E800 surround processor with 3 channels of amplification.

Put a wanted ad in the AV Forum classifieds. It shouldn't cost you very much though it's quite a hefty lump to post.

The DSP E800 provides the 5.1 processing you need for proper surround sound. It drives the center channel and rears leaving your stereo amp to drive the fronts.

The Yamaha has been discontinued for quite a while but works wonders if you can get hold of one. I use one just for DVD film watching with my stereo system to avoid wasting money on an expensive AV Receiver. I like the sound quality of the Yamaha combined with my stereo system. :smashin:
 

Tone DeFeet

Active Member
Thanks for the tip I'll keep an eye out for a DSP E800 but the Mrs. is getting pretty hacked off with me pumping dough into the stereo, which is why I resurrected the old cheapo sub. ;)

Any idea about the "PFRRRRRRRRRRR"?
 

Nimby

Distinguished Member
Just to be certain: You are running two cables from the speaker terminals on your amplifier to the high level connections on the subwoofer?

Do you have the volume set low on the subwoofer and the stereo amp?

I'd turn everything off before messing with any cables.

PS If you are strapped for cash stop wasting it on fancy cables!
 

Tone DeFeet

Active Member
Yup everything as above. :smashin:

..... regarding the cables "ok mum"! :D

I did make my own interconnects tho.
 

Nimby

Distinguished Member
If you want to save some more money then use ordinary lighting flex to connect the sub by high level connections. The sub and amp will never know due to the high impedance and low currents involved.

Perhaps the sub got damp or too hot up in the loft?

If it isn't a quality sub you may be wasting time with it anyway.

Better no sub than a bad sub.
 

Tone DeFeet

Active Member
I had a peek inside and all looks ok. It sounds to me like a capacitor noise and I wondered if it might have been a common fault with hi level inputs.

Better no sub than a bad sub.
I hear ya.
 

The latest video from AVForums

Fidelity in Motion's David Mackenzie talks about his work on disc encoding & the future of Blu-ray
Subscribe to our YouTube channel
Support AVForums with Patreon

Top Bottom