Maybe a stupid amp question for the guys at SVS (1 Viewer)

[JerryW]

I've been searching around for an amp for my soon to be purchased 25-31CS and I'm curious, can a person use a car amp on a home sub?
http://www.valcoelectronics.com/caudio/la220.htm But, my budget is stretched really thin these days.
Thanks.
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September 11, 2001
"Those who died will always be remembered.
Those who killed will never be forgotten.
We who remain will not let it happen again."

 

[BryanZ]

By the time you add in the power converter, you may be better off getting a cheap stereo to use to power it. Perhaps even a cheap monoblock sub. Look around for used amps and receivers. Pawn shops, thrift stores, and garage sales can yield excellent deals.

 

[JerryW]

Well, the amp is $52 and the power supply is $46.
http://www.valcoelectronics.com/psupplies/ps14.htm
So, with shipping I can have almost 300W of power for $110. Not bad.
Anyone think this is just a completely stupid idea?
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September 11, 2001
"Those who died will always be remembered.
Those who killed will never be forgotten.
We who remain will not let it happen again."

 

[Ryan Schnacke]

Well, completely stupid sounds pretty harsh. But do you really expect to get 300 watts from a brand new $52 amp? Shoot, the description and the picture don't even agree. The description says
quote: Legacy LA220 300 Watt 2 Channel Bridgeable High Performance Car Audio Amplifier
(...) 2x150 Watts Total Output, 1x300 Watts Output Bridged Mono[/quote]
But the amp in the picture clearly has "LA220" and "200 Watt" printed on it.
I'm sure you could use this. But it'd be an ugly set-up. And who knows if it would play loud or clean. I'd feel more comfortable buying a used amp at a pawn shop, where I could at least try it out first.
[Edited last by Ryan Schnacke on November 05, 2001 at 03:43 PM]

 

[JerryW]

Well, bridged it's 200W into an 8ohm load and 300W into 4ohm. Looks really don't matter to me as I'll have it tucked in behind some furniture.
My reasoning is that if Tom could use a KLH stereo receiver (2x100W) to power a pair of CS subs successfully, and they sounded great, then maybe this would perform pretty well too.
Again, this is just a thought.
Also, I'd be getting these from a source that the company I work for buys from regularly... if they really suck I can RMA the suckers.

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September 11, 2001
"Those who died will always be remembered.
Those who killed will never be forgotten.
We who remain will not let it happen again."
[Edited last by JerryW on November 05, 2001 at 04:04 PM]

 

[Trey Jones]

Go to parts express and order one of their 250 watt plate amps. They are going for about $135-140 with a remote adjustment knob.

 

[Geoff L]

Jerry,
Though your idea will work, this is not the way to go......
Finding a power supply AC to DC converter that is capable of supplying enough currant when the sub wants it, will be very expensive. (Not to mention the cheaper ones cabable of the currant needed are very noisey, currant wise)
Any 100 watt two channel reciever, Amp, or DC-Amp will more than supply enough jucie to shake your foundation. Even 50 watts will suprise you with an SVS.
All kinds of 100 watt two channel $100.00 recievers by many brands are available daily at BB and CC. {Barter a little for a better price}! Though you will only use one channel, thus leaveing an extra one for future use. Maybe another SVS or a rear center!
In short the car amp is a bad idea, to work properly will cost far more than a new cheap two channel receiver. Also the amp your looking at, the specs are over rated for power. ~(I sell them)~ It will play clean but at about roughly half rated power. Im not trying to rain on your idea, but it's just bad from the get go. Not to mention very ugly in a HT room, just my opinion...
The suggestion on pawn shops, garage sales, ect, and I will add Ebay into the mix, can find you what you need and at a very very reasonable price giveing you the performance you will desire.
Good luck
Geoff

 

[Wayne A. Pflughaupt]

Finding a AC to DC power supply converter that is capable of supplying enough current when the sub wants it will be very expensive.

I’ll elaborate on this a little: There are two ways to deliver power in the electrical world: Voltage and amperage. If less of one available, an excess of the other is required to get the job done. For example, consider how much amperage is required to do the smallest electrical tasks in a car: for about as much amperage as it takes to operate a few light bulbs, you can run a washing machine in your house!
Likewise, an amplifier’s ability to deliver its rated power is a function of available voltage and amperage. With home amps there is a lot of voltage available, so they need relatively low current (amperage) for optimal performance.
Car amps have to work with low voltage, so they need tremendous amounts of current. For instance, the 50 x 4 amp in my car (200 watts total) has a pair of 30-amp fuses—so it takes up to 60 amps to deliver 200 watts RMS.
As you can see, Jerry, there is no way the amp you want to use will deliver anywhere near 300 watts with a DC power supply delivering only 12 amps. You will find that high-current power supplies are much more expensive than just buying a decent home amp.
Also, a lot of budget power supplies deliver “dirty” power--that is, less than pure DC voltage)--and can introduce audible hum and/or other artifacts.
Regards,
Wayne A. Pflughaupt
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My Equipment List

 

[Tom Vodhanel]

two mains things to consider,
1)how many amps will the unit draw at full output into a single 4ohm load when bridged? Likely more than 12-14...which is the limit on the PS.(plus,the inexpensive PS can be hell-a-noisy in a good home system)
2)how accurate are the specs?
As others have noted...the PE $125(250w) plate amp would seem to be a much safer choice.
TV

 

[JerryW]

Ok... I relent. I'll just bite the bullet and get a 2 channel amp. PE has one in particular that looks pretty good. http://www.partsexpress.com/pe/showd...=5436&CATID=46
It should put out about 300W@4ohms if it's bridged.
------------------
September 11, 2001
"Those who died will always be remembered.
Those who killed will never be forgotten.
We who remain will not let it happen again."

 

[Tom Vodhanel]

MCM was selling the 200w per channel fidek for $199 recently. Might also be considered,
TV

 

[JerryW]

Tom, if a person only had (at most) $200 to spend on sub amplification that's what you would recommend?
------------------
September 11, 2001
"Those who died will always be remembered.
Those who killed will never be forgotten.
We who remain will not let it happen again."

 

[Tom Vodhanel]

If it meets your *faeture-set* needs, it would be a value.
If you needed a LP crossover or speaker level inputs(for example)than the plate amp from PE would be the way to go.
I would take the fidek over the pyramid amp...but only because I have personal experience with the fidek unit.
TV

 

[Brian Treinen]

Jerry,
About a week ago I picked up this amp - http://www.partsexpress.com/pe/showd...=9388&CATID=43
Turned out to be $135 shipped and I made a simple box for it. I didn't have to defeat the bass boost, it came correctly defeated!! I was on the fence for a long time between the 20-39PS and 20-39CS and some outboard amplification. I'm very happy I went this way. Tons of power, tons of bass. Good luck.

 

[JerryW]

Wow, you're sure it was shipped with the BB properly disabled? If that's the case, then that looks like a great direction to go. Not that I'm afraid of soldering, it's just that I don't have a lot of experience working on small components. Plus, I was thinking that I would really like the flexibility of adding a 2nd sub in the future. Much to think about...
Hmmm... actually, wouldn't it be cool if a person were to set the boost on that amp to +3dB in the 20-23Hz range if you were going to get a 25-31CS that's custom tuned to 24Hz (or even just buying a 25-31CS that's un modified)? I would think it would make the response pretty much flat down to 20Hz with a decent amount of bass left into the 15-19Hz range due to the roll-off. And you wouldn't be sacrificing as much extension because you'd have a lower overall enclosure "size" (due to a shorter port).
Comments?
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September 11, 2001
"Those who died will always be remembered.
Those who killed will never be forgotten.
We who remain will not let it happen again."

 

[Brian Fellmeth]

Sorry Jerry, that dog don't fly. You can squeeze some extension out of a SEALED sub with low boost, but a driver cannot put significant energy out of a ported enclosure below its tuning frequency by giving the signal a little boost. Thats the trade off of a port- extension hangs in to the tuning frequency then drops like a stone below it.
Also, you casually mentioned bridging 2 channel amps to double the avaliable power. Don't assume that any old consumer receiver or amp can be bridged- this is tricky. Unless the amp is specifically designed to be bridgable, results are lilely to be poor and possibly involve acrid smoke.

 

[JerryW]

Ummm... ok. It was just a thought. I guess there really isn't a way of getting something for nothing.

Also, you casually mentioned bridging 2 channel amps to double the avaliable power. Don't assume that any old consumer receiver or amp can be bridged- this is tricky. Unless the amp is specifically designed to be bridgable, results are lilely to be poor and possibly involve acrid smoke.

Understood, but I only mentioned bridging those particular amps because their literature said they are bridgable. I wouldn't consider doing that with just any old receiver.
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September 11, 2001
"Those who died will always be remembered.
Those who killed will never be forgotten.
We who remain will not let it happen again."

 

[Brian Treinen]

Jerry,
About the boost being disabled - yes for sure it was shipped with 0 boost. I talked to PE before and they said there has been such a demand to kill the boost they normally ship the amp with a bunch of resistors just for that purpose and have requested the manufacturer to disable it standard and allow people to add if they want.
I didn't get any resistors so I went to Radio Shack, naturally the ones I needed only came in a variety pack of 1000 which was like $10. I bought them, went home and took the amp apart and prepared for surgery. I, too, was quite aprehensive since I haven't ever done anything like this before. For whatever reason I checked the exisiting resistors on the preamp to see what they were rated after I had calculated the color combo I'd need - lo and behold they were set for 0 boost! I called PE and the tech said I must've gotten a newer one and the manufacturer was finally listening to them. I went over the color combo with him and he verified it was the right parts to defeat boost!
As far as upgrading to two subs in the future, I figure for another $135 I can add another amp and build another box and it won't have cost me much more than buying the Fidek (for example) now. Besides, my wife said there is no possible way we're getting another sub. ;^) But we know how that goes!!

 

[Marcelo T]

JerryW, I had the same idea, to use a car amp to drive a sub, but it seems to be a really bad idea. You guys really spoiled my fun
[Edited last by Marcelo T on November 09, 2001 at 01:47 PM]