Ampeg SVT Cab Crossover

[Skinhorse]

Hello!

I have Ampeg SVT 410HLN cabinet and the crossover seems to have stopped working; apparently this is a common fault. The horn controller has completely stopped working and cab seems a lot less responsive. I have replaced all four 10" speakers, cleaned/checked the wiring, replaced the bulb and used my head with a similar Ampeg cabinet (to rule out the head) but it continues to sound dull and quiet.

Has anyone been able to source a replacement crossover for Ampeg cabinets?

Many thanks!
Ben

 

[T-Bird]

Hi Ben.

The search for Ampeg SVT 410HLN crossover proved unfruitful for some reason, but I'd be surprised if there was anything fancier than 2nd order LP/HP somewhere around 2K + the L-Pad attenuator for the Hi-Freq in there.

Can You take a pic (both sides) or even draw a sketch of the crossover?

Except for the HF protection bulb(s), there's really not too many components that can go bad, but craked solder joints or broken leads is always a possibility.
Especially with heavy inductors.

The dullnes and quietness in multi driver cabs is very often a result of polarity problems, one or more speakers are 180deg out of phase with the rest.

9V battery test will reveal that.

Regards
Sam

 

[Skinhorse]

Hi Ben.

The search for Ampeg SVT 410HLN crossover proved unfruitful for some reason, but I'd be surprised if there was anything fancier than 2nd order LP/HP somewhere around 2K + the L-Pad attenuator for the Hi-Freq in there.

Can You take a pic (both sides) or even draw a sketch of the crossover?

Except for the HF protection bulb(s), there's really not too many components that can go bad, but craked solder joints or broken leads is always a possibility.
Especially with heavy inductors.

The dullnes and quietness in multi driver cabs is very often a result of polarity problems, one or more speakers are 180deg out of phase with the rest.

9V battery test will reveal that.

Regards
Sam

Thank you Sam, I will grab the cab and post some photos up within the hour!
Many thanks!

 

[Skinhorse]

Apologies for not adding any photos yet, In the meantime, I have been pointed in this direction by the Mackie Factory Repair Center Europe.

[Invalid or Expired Link Removed]

This is the part in question, but unfortunately they are out of stock until October.

 

[beans-on-toast]

I have replaced all four 10" speakers, cleaned/checked the wiring, replaced the bulb and used my head with a similar Ampeg cabinet (to rule out the head) but it continues to sound dull and quiet.

Have you tried the battery test that Sam mentioned? This will tell you if all the speakers are connected in phase.

Normally you would disconnect the horn, plug a speaker cable with a ¼" plug to the cabinet, and momentarily touch a 9 volt battery to the tip and sleeve of the ¼" plug, you should see all the speakers moving either in or out in unison. If one is moving in the opposite direction of the others, it is out of phase and the cable connections to it need to be reversed.

The other possibility that you haven't mentioned is that the horn has blown. It needs to be tested. Disconnect it and connect something like an MP3 player to it and see if you hear anything coming out of it.

More often, problems with the crossover are in the connectors. Inspect the board carefully and look for any signs of damage, a burnt (black charing) component, a loose component, or a solder joint that doesn't look proper. Reseat all the connectors by pulling them and reinserting them.

 

[T-Bird]

Hi.

Apologies for not adding any photos yet, In the meantime, I have been pointed in this direction by the Mackie Factory Repair Center Europe.

[Invalid or Expired Link Removed]

No worries Ben, that pic reveals quite enough for a start.

If only the manufacturers would use the standardised markings .
The component values are too much to ask from them, that's for sure.

Anyway, looks like one of those "one size fits all" type of deals, great from the manufacturers POV, for the consumer, not that much.

Easy enough to test with a multimeter though.
Looks like the C3+L2 is parallel with the woofers, so lifting one end will take the crossover out of the equation as long as the L-pad assembly is not connected.

Regards
Sam

 

[Skinhorse]

Hi guys, thank you for all your help so far!! I have tried the battery test and all speakers were in phase. The board and it's components we're clean and I re-sat each connector. The tweeter also works fine by itself. But, the problems persist.

I have a gig this evening so no more time to test; I have disconnected everything and removed the entire back-plate. The speakers are now wired to a single jack on a replacement plate. A short-term fix until I can test the PCB and components!

Again, many thanks for your help, it is greatly appreciated!

Ben

Sent from my iPhone using TalkBass

 

[beans-on-toast]

You covered some of the bases that needed to be looked at. I would inspect the solder joints on the crossover board. The red coil doesn't have the ends glued down and they may have been vibrating. Carefully tug in the wire at each end to make sure that they are soldered well onto the board. Sometimes the joint looks good but the connection isn't.

 

[Chris 'Wighat' Jordan]

What did you replace the 10's with?

 

[Skinhorse]

You covered some of the bases that needed to be looked at. I would inspect the solder joints on the crossover board. The red coil doesn't have the ends glued down and they may have been vibrating. Carefully tug in the wire at each end to make sure that they are soldered well onto the board. Sometimes the joint looks good but the connection isn't.

Thanks man, I will check the red coil. And, I replaced the speakers with four Eminence Legend BP 102-4 Bass Guitar 10" Speakers-- 4 Ohm /200 Watt.


Sent from my iPhone using TalkBass

 

[anderbass]

Has anyone been able to source a replacement crossover for Ampeg cabinets?

Try this shop: http://www.service.lselectronics.net/

 

[will33]

Check for a break in the circuit through the l-pad and/or lightbulb socket.

That's a simple 12db filter, not as much going on as the diagram posted further up. Not too many things to go wrong there.

 

[will33]

Hi.



No worries Ben, that pic reveals quite enough for a start.

If only the manufacturers would use the standardised markings .
The component values are too much to ask from them, that's for sure.

Anyway, looks like one of those "one size fits all" type of deals, great from the manufacturers POV, for the consumer, not that much.

Easy enough to test with a multimeter though.
Looks like the C3+L2 is parallel with the woofers, so lifting one end will take the crossover out of the equation as long as the L-pad assembly is not connected.

Regards
Sam

Was trying to make sense of the 3 capacitors as I did not see an actual part in the L2 spot.