[flashollie]

Originally Posted by t5pilot

So, they don't sound quite"right"?
That's what I would expect tbh. Yeah, if you just leave them like that, they will probably deteriorate until the HK amp gives up & fries.
Like I said, just check carefully if that Audison amp is actually compatible.
I remember my choices were very limited. I was fortunate, as I like Hertz stuff, it was the first manufacturer I checked.

Yeah they don't sound right, better than the stock but not right.
So speaking to the car audio guy hes said he will use it as a 3 channel set up.
so channel 3 and 4 are bridged to be one channel for use in the future with another sub if I need more oompph
So 4 channels will become 3 by :

130 w x 2 at 2 Ohm channels 1 and 2 (my woofers are 90w RMS at 2 Ohm) and the 3rd (bridged 3 and 4) will be idle at 260w at 4 Ohm

[t5pilot]

Ah, I see. I didn't know you could have an 'idle' channel if using the other part of the split. Nice one, this should work a treat then.
When it's fitted, make sure he shows you where the 'gain' control is. You can then adjust that to your own taste, to get your own ideal volume balance of the woofers. Some like them to blend, others like them to dominate. I'm sort of midway. This needs to be adjusted with the main system volume set at least to 70%. So find somewhere to do it, lol. Cos the whole setup is going to be louder when the HK amp isn't directly driving the woofers. You'll know exactly what I mean when you come to do it.....

[t5pilot]

Originally Posted by winther1

The 4-ohm ISUBBMW4 Focal subs:
Max. power 180W
Nom. power 90W RMS
Sensitivity (2.83V/1m) 83dB
Frequency response 35Hz-200Hz

For comparison, what are the specs for the HK subs?

There is a really technical thread somewhere in the American section.... But it's pretty mind-boggling tbh. And IIRC, I don't think there was a definitive answer on the specs.
BUT... there was strong conclusion that the woofers themselves were good, and will sound miles better if driven from a dedicated amp.

[flashollie]

Originally Posted by t5pilot

Ah, I see. I didn't know you could have an 'idle' channel if using the other part of the split. Nice one, this should work a treat then.
When it's fitted, make sure he shows you where the 'gain' control is. You can then adjust that to your own taste, to get your own ideal volume balance of the woofers. Some like them to blend, others like them to dominate. I'm sort of midway. This needs to be adjusted with the main system volume set at least to 70%. So find somewhere to do it, lol. Cos the whole setup is going to be louder when the HK amp isn't directly driving the woofers. You'll know exactly what I mean when you come to do it.....

Yeah Ive learned quite a bit on all this stuff.
Loads more complex than what I'd hope for with Plug and Play!

[winther1]

Originally Posted by t5pilot

There is a really technical thread somewhere in the American section.... But it's pretty mind-boggling tbh. And IIRC, I don't think there was a definitive answer on the specs.
BUT... there was strong conclusion that the woofers themselves were good, and will sound miles better if driven from a dedicated amp.

SWS might be worth considering too if a straight swap - certainly seems more powerful:
Earthquake Sound SWS-8X, 4 Ohms:
Specifications:
• Model: SWS-8X
Size: 8" high performance sub
• Freq resp: 20-300Hz
• Max Power: 300W
• RMS Power: 150W
• Impedance: 4Ω
• Sensitivity: 86.7dB

[t5pilot]

Originally Posted by winther1

SWS might be worth considering too if a straight swap - certainly seems more powerful:
Earthquake Sound SWS-8X, 4 Ohms:
Specifications:
• Model: SWS-8X
Size: 8" high performance sub
• Freq resp: 20-300Hz
• Max Power: 300W
• RMS Power: 150W
• Impedance: 4Ω
• Sensitivity: 86.7dB

I've heard the earthquakes & they're not bad at all. They're just a bit boomy (imo of course). After my Audisons, second choice would have been Bavsound Ghosts, followed by the Focals, with the earthquakes in 4th.
Let's be right though, they're all very good, given the lack of flexibility in mounting replacement woofers & sound pretty incredible when amped properly.
If you listen to any of these, you can't be anything other than impressed.
I was lucky as I'd heard the Audisons in direct comparison to earthquakes. And I've heard the ghosts, but not in direct comparison.
Unless you're an audiophile, I'd go with any of these, based on the best deal you can secure. None of these are cheap.

[dss0110]

Originally Posted by t5pilot

I've done a sub upgrade with additional amp (HK from factory).
Done a couple of write ups. I'll dig them out & post the links...

Edit: Links below...

https://forums.m3cutters.co.uk/threa...ptions.228786/

https://forums.m3cutters.co.uk/threa...eakers.225857/

https://forums.m3cutters.co.uk/threa...eakers.231951/

Hi mate. Read your write up on m3cutters. I noticed you didn’t use a LOC. I’ve got the OEM HK underseats and have already got a sub in the boot wired using t tap connectors, LC2i and JL 500/1 amp. Any advice on how to amplify the HK underseats and how to go about wiring it without the Technic harness?