HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

Tim Catt wrote:

Dr Bunsen Honeydew wrote:I hate subs, unmusical nasty things

what do you hate the most subs, high streets or estate agents?

Silly question.

Dr Bunsen Honeydew wrote:

Tim Catt wrote:

Dr Bunsen Honeydew wrote:I hate subs, unmusical nasty things

what do you hate the most subs, high streets or estate agents?

Silly question.

Its estate agents isn't it...

No probably hi-fi retailers.

Dr Bunsen Honeydew wrote:No probably hi-fi retailers.

On this my freind, we most definitely agree.

Hello all,

I can see this is an old post but hopefully someone is still listening!

I bought a pair of Goodmans Mag Ks recently. Strangely the bass is rather thin, and they sound generally like something is out of phase somewhere.

I'm focusing on the bass first for simplicity. Thus far I have temporarily swapped the existing crossover for a much more recent B&O unit to see if the bass improved. It didn't really, and comparing the sound to my reference wharfedale 505.2 they sound very thin.

I'm going to desolder the bass drivers and while they're mounted in the cabinet connect them directly to the amplifier to see the bass response. If this fails I'm stumped as these drivers in a cab this big should make some bass.

Any help would be greatly a appreciated ad I'm a few tens of hours in so far lol!

Have you done the basic trouble-shooting, such as playing some music and putting your ear next to the woofers to check they are working on each channel?
And placing the speakers face to face, playing some music, swapping the phase on 1 channel and playing the music again, to see which connection gives the louder, in-phase bass?
And checking that the midrange drivers and tweeters haven't been swapped for drivers that are far more efficient. And that the woofers are the original ones, with the correct impedance.

I would agree with what Lindsay says. Are these a sealed design ? If so check the cabinet is still completely sealed. A leak can lower Q and bass output.

Have they been steel lined or the stuffing removed ? I am not familiar with these speakers but reading this whole thread suggests there are potentiometers involved in level setting. These will be very old now and quite possibly fooked. Bloody awful things.

Are the bass driver surrounds in good shape ?

Hello, thanks for your prompt responses.

The cabs are perfectly sealed. Drivers are mint. Everything is as it should be. I replaced all the cables. Pots are a bit duff but they don't affect the bass. It's strange because these are 12" drivers in 50 litre enclosures. They're currently breaking the laws of physics!

If my crossovers are duff then maybe this explains it. I'm going to connect the bass drivers directly to the amp without crossovers as I presume this will provide the driver with the full bass signal. Is my logic sound here? Thanks again

Yeah it's a good idea although you will have to ignore any break up resonances that occur.

50l is not very much for a big driver in a sealed box, when drivers are tested they are usually tested in at least a 300l enclosure to give a set of readings and to plot the resonant peaks

A sealed enclosure will also start to roll off at a comparatively higher frequency than a ported or otherwise loaded cabinet so they can sound thin because they can start to roll off more gradually from a few hundred hz rather than hitting a brick wall at say 60 hz or lower. The port output props up the percieved low frequency extension until it drops off around or just lower than the resonant frequency of the driver
If you are used to ported boxes this can seem abit counter intuitive as a big driver can sound like it has much less bass than a much smaller driver in a smaller box. The strength of a sealed box is that there is no port noise, no lag between the port output and the driver output which can lead to lumpy bass, and a more linear tighter low frequency performance
My speakers use a 15" driver in initially a 120l sealed box, i have now changed this to aperiodic loading with a very large vent with high density wool felt in it.

It may be simply a case of thats how they sound compared to what you had before.

A big driver doesnt necessarily mean big bass. Arbitrarily changing the crossover will not make much difference to the bottom end performance as the big driver will not be cut off at the bottom of its response, it will be cut off at the top of its response to integrate with the driver handling the mid portion of the spectrum. At one end of the spectrum a simple one part crossover using an inductor can be used to roll off the top of that driver, or it can be infinitely more complicated