Help with bypassing sub plate amps

[Liquid Air]

Need help from some of you clever sound guys out here. My House was recently struck by lightning which fried out a lot of my audio equipment including the plate amps of both my Subs and a few various other components. So a friend suggested to bypass both plate amps and connect my Martin Logan and Klipsch RT-12D via 10 gage speaker wire and connect them to an external amplifier which I have a crown 2,500 Watt amplifier. However the signal is not strong enough so I have them run with RCA cables to my separate tube phono preamp to boost the signal. The work, trouble is when I turn it up too loud there is a popping sound like the voice coil is bottoming out and certain bass tones or at medium too loud volume. How can I avoid this and is this the best possible way of hooking things up without replacing the Subs? Thanks ion advance..

 

[lovinthehd]

If your sub's plate amps were fried but not your drivers you could easily use another amp. How you bypass the plate amp could be key, how did you do that?

 

[TLS Guy]

Need help from some of you clever sound guys out here. My House was recently struck by lightning which fried out a lot of my audio equipment including the plate amps of both my Subs and a few various other components. So a friend suggested to bypass both plate amps and connect my Martin Logan and Klipsch RT-12D via 10 gage speaker wire and connect them to an external amplifier which I have a crown 2,500 Watt amplifier. However the signal is not strong enough so I have them run with RCA cables to my separate tube phono preamp to boost the signal. The work, trouble is when I turn it up too loud there is a popping sound like the voice coil is bottoming out and certain bass tones or at medium too loud volume. How can I avoid this and is this the best possible way of hooking things up without replacing the Subs? Thanks ion advance..

You first job and expenditure is to get your house up to NEC 24 electrical codes to very substantially reduce the risk of this happening again. So this means SPD-1 surge protections at the entry of electrical service to your home. Then you need SPD-2 surge protection at every panel.

We need more information about those subs. Are they ported or sealed? If they are sealed then you need original plate amp replacements. If you want to use an external amp then you need to disconnect the sub driver from the plate amp, and connect the sub driver directly to the speaker terminals of your power amp. The plate amp needs to be put back in, or the hole where is was closed up.

Now you do need to check the impedance of the sub driver, as some subs have drivers of unusual impedances.

The last issue is that the drivers may very well have been damaged in the lightning strike, and may well have damaged voice coils with shorted wire turns. So you need to check the DC resistances of the woofers VCs. The DC resistance is usually about 60% of the driver impedance at least, and anything less indicates a partially fried VC. The DC resistance can be as high as 90% of the impedance, but this is unusual. It generally is very close to 60%. The chance of the driver being fried is high after an event like this.

 

[Liquid Air]

If your sub's plate amps were fried but not your drivers you could easily use another amp. How you bypass the plate amp could be key, how did you do that?

I ran the speaker wire form the actualy speaker to a seperate amp then through a phono preamp using RCA then preamp to my reciever, it works but there are trade offs

 

[Liquid Air]

You first job and expenditure is to get your house up to NEC 24 electrical codes to very substantially reduce the risk of this happening again. So this means SPD-1 surge protections at the entry of electrical service to your home. Then you need SPD-2 surge protection at every panel.

We need more information about those subs. Are they ported or sealed? If they are sealed then you need original plate amp replacements. If you want to use an external amp then you need to disconnect the sub driver from the plate amp, and connect the sub driver directly to the speaker terminals of your power amp. The plate amp needs to be put back in, or the hole where is was closed up.

Now you do need to check the impedance of the sub driver, as some subs have drivers of unusual impedances.

The last issue is that the drivers may very well have been damaged in the lightning strike, and may well have damaged voice coils with shorted wire turns. So you need to check the DC resistances of the woofers VCs. The DC resistance is usually about 60% of the driver impedance at least, and anything less indicates a partially fried VC. The DC resistance can be as high as 90% of the impedance, but this is unusual. It generally is very close to 60%. The chance of the driver being fried is high after an event like this.

You first job and expenditure is to get your house up to NEC 24 electrical codes to very substantially reduce the risk of this happening again. So this means SPD-1 surge protections at the entry of electrical service to your home. Then you need SPD-2 surge protection at every panel.

We need more information about those subs. Are they ported or sealed? If they are sealed then you need original plate amp replacements. If you want to use an external amp then you need to disconnect the sub driver from the plate amp, and connect the sub driver directly to the speaker terminals of your power amp. The plate amp needs to be put back in, or the hole where is was closed up.

Now you do need to check the impedance of the sub driver, as some subs have drivers of unusual impedances.

The last issue is that the drivers may very well have been damaged in the lightning strike, and may well have damaged voice coils with shorted wire turns. So you need to check the DC resistances of the woofers VCs. The DC resistance is usually about 60% of the driver impedance at least, and anything less indicates a partially fried VC. The DC resistance can be as high as 90% of the impedance, but this is unusual. It generally is very close to 60%. The chance of the driver being fried is high after an event like this.

It is a Klipsch RT-12D. That is a triple sub, one sub facing forward 2 Passive radiators to form a triangle non ported. I did bypass the plate amp totally and connected speaker wire to the. Speaker terminals. But there was not enough. Juice in the line even though I hooked it up to a 2500 Watt amp so I had to run it through a phono preamp. So I thought I had too much amp pushing them which is why I'm hearing the voice coil bottom out. But I will get with my friend and have him check what you suggested about. Checking the resistance on the VC. Thank you so much.

 

[ski2xblack]

I did bypass the plate amp totally and connected speaker wire to the. Speaker terminals

I hope you meant you connected the speaker wire directly to the driver, and not the speaker level inputs on the plate amp.

The Crown may have lower gain than whatever is powering your mains, which can be compensated for by trimming back the other channels relative to the sub channel.

Introducing RIAA equalization by inserting a phono pre into the sub channel is not helping. So lose that and trim back the other channels instead.

Those subs are reflex designs using passive radiators instead of ports, and the passive radiators will decouple from the active driver at some point down low, so you really need to high pass the sub amp with a subsonic filter to prevent it from destroying the sub with subsonic material. I don't know exactly where that will happen with the Klipsch sub, probably mid to low twenty hz area, but with such power on tap, it's necessary. Some Crown amps have such filters. Does yours?

 

[TLS Guy]

It is a Klipsch RT-12D. That is a triple sub, one sub facing forward 2 Passive radiators to form a triangle non ported. I did bypass the plate amp totally and connected speaker wire to the. Speaker terminals. But there was not enough. Juice in the line even though I hooked it up to a 2500 Watt amp so I had to run it through a phono preamp. So I thought I had too much amp pushing them which is why I'm hearing the voice coil bottom out. But I will get with my friend and have him check what you suggested about. Checking the resistance on the VC. Thank you so much.

As others have said, that is the WRONG way to do it. You can't use an RIAA phono amp as it has the RIAA curve and is miles away from flat.

Trim the levels. Be careful, that sub is an ABR unit. The passive radiators replace ports, but decouple from the box alignment fast. So a ported sub rolls off at 24 db per octave below F3 but an ABR at 36 db per octave. So in those designs there is usually a high pass filter around F3 to prevent driver over excursion. So not high passing the driver with your external amp could be causing damage if you play content with a lot of deep bass at high volume.

 

[lovinthehd]

I ran the speaker wire form the actualy speaker to a seperate amp then through a phono preamp using RCA then preamp to my reciever, it works but there are trade offs

Not sure what speaker wire from the "actualy speaker" means....but a phono pre-amp is definitely not something to use due RIAA eq being applied. Got pics of this setup/wiring?