Wharfedale Diamond 9.1 + Marantz PM6004 Bass Distortion Issue


Novice Member
Hi all,

so I've hooked up my Wharfedales and Marantz amp for the first time, hoping to have my first "dream set up".

All working well so far but I have an ongoing bass distortion issue with the speakers and I can't figure out how to fix it...

So far all I've tried is using the Source Direct function on the amp, which works sometimes, but not always. And this is even when the bass control is turned down to 0.

Any tips and suggestions welcome!


Active Member
Without hearing it, it's almost impossible to know what is causing it. Is it both speakers or just 1? Does it sound like the bass cone is distorting? or vibration from the cabinet?

Helix Hifi

Well-known Member
If the speakers are blown, then the bass cones are going to make scratching noises.

You’ll hear it immediately.

Just to be sure. Stream piano music. Listen to the tweeter. If it does sound normal, then it’s fine. If the tweeter makes scratching sound, then it’s not fine.

Then stream bass heavy music.

Blown speakers are easy to spot. If it sounds normal, no damage.
There can be good news too.

While streaming music loud, not too loud. There might be vibrating sound from the speakers. Then the book shelves cabinet etc, is going to make annoying vibrations sound, epically from bass heavy music.

Then try to put sorbothane feet’s underneath the speakers, this should help.

While streaming music, it’s never wise to have the volume too loud. If the speakers starts to sound thin/stressed. Then turn the volume down, immediately!

The Marantz amplifier is quite powerful, though if you have the volume too loud, then of course there are going to be scratching noises.

Btw, I advice you to use speaker cables with banana plugs. I seem to remember it says in the Marantz manual, if there are ongoing issues with the sound, then check if the connections are okey.

Helix Hifi

Well-known Member
The reason I’d advice you to stream piano music, is because this kind of music has lot of high frequency information.

So the tweeter should sound clear, open, then it’s fine. As mentioned it should not be difficult to see if the speakers are blown.

How loud is the volume control when this issues appears?

The Marantz amplifier is 40 watts amplifier. I can’t remember what the sensitivity, ohm the speakers have.

Still this combination should be fine. Though I’d advice you to not listen any louder then minimum 9 a clock.

Or when the volume is nice and clear.


Novice Member
Ok thanks so much. I'll try some banana plugs as it's bare wire at the moment.

I NEVER have my music too loud as I'm very conscious of my neighbours, the volume dial is literally at 7o'clock and no higher, ever.

They're brand new speakers so it can't be that they're blown, especially as I never turn the volume up.

Issue is occuring when I connect turntables to the amp via phono AND when I use a jack-to-RCA via my laptop. Not every single thing I play on the laptop causes distortion, but a fair few mixes I've played have been problematic.

Speakers are not on stands or against a wall.

Helix Hifi

Well-known Member
No TT expert, so can’t help you there. But it can be the cables are broken. Or the plugs on the cables.

My theory the analog inputs are broken on the amplifier. Does it only happens when you adjust the volume?


Well-known Member
The only thing I can suggest is that your amp has developed a fault. Can you get access to another amp to test, then if that shows nothing then try to test the am with another set of similarly specified speakers.
The 6004 model is getting a bit long in the tooth now so might have developed a fault.

Helix Hifi

Well-known Member
7 o’clock is not loud, not loud at all. I’ve owned Marantz amplifiers before with analog volume controls.

The volume controls needs to be around 8 o’clock to be reasonable loud.

If the volume starts to act strange then, it’s probably something wrong with the amplifier.

Did you buy it used?

As mentioned the analog inputs might be broken. Classic symptoms are crackling sound when the volume is adjusted.

Then you need to solder the analog inputs.

Or it can be the speakers. You need to do AB/testing to rule out if it’s the TT or the laptop.

Doubtful it’s the speakers...

As mentioned try and use banana plugs instead of bare wire. Much more secure then bare wire.

If you want to continue using bare wire, you need to tighten the speaker terminals.

You need to use some gentle force then. With banana plugs, this is not necessarily.


Novice Member
I think it was just as simple as the volume from my inputs (mixer and laptop) was too high. Didn't realise how powerful the amp was til now...

I'm making sure the volume is low on my devices, and using the amp volume dial as the main way to adjust loudness and it seems to be working.

Total novice here, obviously!


Distinguished Member
Speakers rarely go wrong if well looked after.

Do you have another working amp to rule out the Marantz amp?

Has the amp ever been serviced?

Do you have another pair of speakers you know are working fine to try on the Marantz amp?

edit: ignore my post, I usually read threads and my own posts after I post.

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