Gale Gold Monitor into Camper Van

[raygreen]

If there is anyone out there with expertise in building speakers. I have taken apart 2 Gale Gold Monitors and rebuilt boxes from 3/4" MDF to fit in my VW Transporter. I have even inserted the bass cones to the design (Sorry I should have included a photograph - could do this another day). The bass and tweeter are fixed onto the face of the speaker which is covered by a carpet trim used to line vans. This is then screwed to the speaker box to close up the speakers (the carpet does wrap around the face and would not produce an air tight seal (DOES THIS MATTER?). I have used quality cables and everything is connected up as it should be.

I listened to the Gale's on my hi-fi system and they sounded pretty good (not as good as my Celestions I might add!). The boxes for the Gales were damaged so I did not mind taking them apart.

I am getting quite a lot of distortion in the bass with any reasonable volume or with any music that is bass heavy.

My care stereo is a Blaupunkt RCD200 - I think this provides 20W per channel. The front speakers are the factory fitted ones. OK but nothing special. I expected the Gales to blow them away.

Why are these not reproducing the same quality sound. Is it the head unit or the boxes?

[Macca]

could be a number of things but if we assume the head unit is fine and it is the speakers at fault then what changes did you make when you put them into the new cabs? Did you transplant the crossover complete or did you take that apart too? if you have missed a component out that could be causing the problem.

If that is not the issue check the bass drivers for damage. An air leak in the cab will not cause bass distortion.

[awkwardbydesign]

The head unit may be 20w peak into 4ohms. Which is a hell of a lot less than you would need for loud and bass heavy with domestic speakers!

[raygreen]

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What I meant by the sealed unit is around the speaker box, not the cab of the van. I tested these before by connecting my Arcam Alpha to the Gales and I am still getting distortion. At mediocre volume or music with relatively moderate bass I am getting some buzzing from the bass cones. The sound is also not as sweet or crisp as it should be.


The boxes are not the actual size that they look in the photographs as there is a small shelf built in which is at the level just above the tweeter. However taking the original Gale boxes into consideration they are perhaps larger in volume than I thought due to their triangular shape.
One thing I will try is squaring these off which will make the volume smaller and inserting some speaker fleece. Would this smaller volume produce a tighter, crisper and punchy sound? Will the fact that the ports are facing sideways make any difference? Thanks. It is an interesting exercise sorting this one out but I will look forward to listening to an improved sound on the car park that is the M60 on my way into work.

[awkwardbydesign]

If you change the box volume from the original, then the ports will be wrong. I would keep the larger volume boxes for now, block the ports and mount the drivers properly; seal them to the cabinets without leaky carpet. That includes the tweeters! Make proper SEALED boxes and see how that is. If the bass drivers are not loaded properly, that is sealed so the back pressure controls the cone movement, or a correctly designed ported box, you may get the bass drivers hitting the stops. And buzzing! Side facing ports shouldn't make much difference.
Sealed boxes generally give tighter bass, but it all depends on many variables.
And when Macca referred to the "cab" I believe he meant speaker cab(inet).

[raygreen]

If you change the box volume from the original, then the ports will be wrong. I would keep the larger volume boxes for now, block the ports and mount the drivers properly; seal them to the cabinets without leaky carpet. That includes the tweeters! Make proper SEALED boxes and see how that is. If the bass drivers are not loaded properly, that is sealed so the back pressure controls the cone movement, or a correctly designed ported box, you may get the bass drivers hitting the stops. And buzzing! Side facing ports shouldn't make much difference.
Sealed boxes generally give tighter bass, but it all depends on many variables.
And when Macca referred to the "cab" I believe he meant speaker cab(inet).

That all sounds like it makes sense. The problem does sound like it's with the cab (inets......sorry Macca). Will have to have a re-think at the weekend. I will probably start thinking a pair of 6x9 car speaker would have been such an easy option.

[Macca]

I'm not convinced the problem is the ported cabinets but it is really hard to diagnose these things remotely so who knows. The 6X9 car speakers might be a better idea, they will be a lot more efficient than the Gales and that could be the issue.

[awkwardbydesign]

I'm not convinced the problem is the ported cabinets but it is really hard to diagnose these things remotely so who knows. The 6X9 car speakers might be a better idea, they will be a lot more efficient than the Gales and that could be the issue.
That's true, and they would cope with temperature, humidity and vibration better too. I wonder if it is the van panels vibrating?

[Reffc]

Sounds like it could be any number of things: getting the ports wrong is unlikely to cause bass distortion as you describe it unless the box you've used and the ports have together lowers the tuning point below the resonance point for the bass drivers.

The amp I think is 200WPC and not 20WPC (4 Ohms) but I could be wrong. If it's 200WPC it's unlikely to be distortion due to clipping. If it's 20WPC then its highly likely it's distortion due to clipping. Check the amp connections again and also that you have it all wired up correctly would be a good place to start.

Getting the port tuning out wont necessarily cause distortion as you describe unless you've tuned lower than the resonance point of the speakers (port volume and diameter are a fixed relationship for the correct tuning point for a specific volume dictated by the Thiele-Small parameters for the drive units, namely, Vas, Qts and Fs). If you compare the new box volume with the old, what do you get? Have you used ports or gone with sealed boxes?

[awkwardbydesign]

This is fun. I suspect it has gone way more technical than the OP bargained for! :lol:

[raygreen]

Oh yes......

My neighbours son was back tonight who has build some very nice speakers of all sizes. He had a listen and reckon I need to adjust the following;

- Reduce the volume size which is why they are sounding a little muffled
- seal the electrics from behind so they are air tight - losing a lot of pressure through there
- line the insides and base with speaker fleece
- seal the insides with silicone sealant
- remove the carpet from around the base drivers and front panels
- one of the base drivers was not as secure as it should be causing a little vibration

I will also find some thin rubber sheet and cut out a template to fit behind the speaker cones for an air-tight seal. He thinks that will bring them up to what they were. Worth a try... will be fun...