# Thinking of using a cheater amp for a tri way config



## Buickmike (Aug 10, 2012)

I'm sure most of you are not a fan of using a 2 channel amp in a tri way config, but don't knock it until you try it. I've done it with a couple small amps in the past due to budget constraints and I have to say there is something that is very natural sounding when using this setup. Probably because everything is in lock step. 

Back in the day I had a Hifonics Cupid running tri way with a 4 ohm sub, and a set of components. It was really clean, but not super loud. The amp did great though. It ran at 1/2 ohms of what it was rated at all day long and never got hurt.

So now I'm thinking to recreate this, but step it up a notch with an old school cheater amp that is 1/2 ohm stable. Not sure if that is a good idea or which amps would be good. I still find affordable HCCA 225's every once in awhile, but am not sure if they are clean when pushed to low ohms. I would love one of the OS Hifonics Platinum amps, but when they show up, they are $$$

Any thoughts on this?


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## GEM592 (Jun 19, 2015)

Maybe the most important amplifier engineering concept is the gain-bandwidth product. Roughly this means that the wider the bandwidth you require a channel to drive, the less clean power you can expect. When you run tri-way your bandwidth demand per channel is maximized. At high power, even the best amp is going to tend to mix low frequency power into the upper frequencies (Intermodulation distortion) that will pass your crossovers and get delivered to your mids and tweets. This is why these days most don't try this. This is also why the typical sub upgrade with a separate amp is so easy to sell - right away it cleans up the rest of the system.

I do understand the appeal. A three way system with only one two channel amp that sounds good at power would be a novel achievement - very cool. But it is hard. However, if your results are good I say that's good enough. I would think headroom would be extremely important - you basically want a big big amp. Also the crossovers would be crucial. You would need a very clear sense of how load impedance varies with frequency to choose a good amp. And limited/lack of independent level control would I think be a problem at high power levels - if you want to turn it up your crossover would need to account for this.

I don't doubt that the tri-way approach may sound very good at lower volumes. Just about every decent stereo does. I think you would need to be satisfied with low listening volumes to have success, which is fine.


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## Buickmike (Aug 10, 2012)

I sounds really clean at reasonable volumes. The couple times I did it, I had help building 12db/octave passive x-overs. I was just thinking that with more power it would be a fun experiment.


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## smgreen20 (Oct 13, 2006)

One of the baddest of the bad boys would be a LANZAR Opti50c. 1/4 ohm stable stereo at 400w per ch. THD at that power was around .01%

Sounds like it would fit your needs/wants/requirements.


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## wheelieking71 (Dec 20, 2006)

Here, let me give you some advice. I can not explain the science behind what I am about to say. But, I have been playing with this stuff for a very long time. I do know a few things. Quit worrying about "cheater amps" and 1/4ohm loads. If you need the headroom of 400watts per channel? Buy a 400watt per channel amplifier. At 4ohms, or 8ohms, or whatever nominal impedance the drivers you are using happen to be. Don't stack a bunch of drivers in parallel to load the amp down, to make a bunch of power. Do you listen to music? Or test tones? Seriously. Tri-mode is a great option, and can sound fantastic. I know, I have done it many times. But, if you need power? buy a bigger amp, and run it at reasonable loads. Your ears, and your amp will thank you.


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## vwguy383 (Dec 4, 2008)

I'very done tried mode before and loved it. I had set of 5.25 boston comp running stereo with 2 8wo's mono on a PPI PC2300.2. People couldn't believe that I was running everything off that little amp. Go for it man!


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## Buickmike (Aug 10, 2012)

Thanks for all the advice. Not exactly looking to load a cheater amp to the max, but would love to have something that can handle between 1.5 and 2 ohms per channel with plenty of headroom to go.


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## GEM592 (Jun 19, 2015)

Buickmike said:


> I sounds really clean at reasonable volumes. The couple times I did it, I had help building 12db/octave passive x-overs. I was just thinking that with more power it would be a fun experiment.


I would definitely encourage the experiment. Anything that goes against conventional wisdom but is well thought out and interesting I am all for.


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