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Old 8th January 2008, 10:04 PM   #1
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Default Carver PM1.5A - Bridgable?

I'm thinking no, but there are a lot of wiser people than I on here. I have two and would like to put them to good work.

Thank you in advance.
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Old 8th January 2008, 10:17 PM   #2
anatech is offline anatech  Canada
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Hi AltheaToldMe,
They are bridgeable, but watch your speaker impedance and your AC supply impedance. Practically speaking, the amplifier will probably run into trouble due the poor AC line regulation.

Now for one last question. Do you have any idea how much power you are dealing with in normal stereo mode???? How about in mono-bridge mode? You will run out of AC power before you run out of Carver power. Your speaker(s) may offer themselves up to the fire god. Most woofers will not be able to handle the full output from a Carver in normal mode for very long, not unless your AC supplies are drooping badly.

Last point. If you are really going to do this (recommend that you don't), the old filter caps may give up the ghost. You had better have that amp serviced properly before you embark on this idea.

-Chris
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Old 9th January 2008, 12:28 PM   #3
djk is offline djk
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On 10mS tone bursts at 8R in stereo, a PM-1.5 can put out in excess of 200V peak-to-peak.

This implies 400V P-P bridged.

At 8R in bridge mode on bass the collector bond wire for the outputs could fail (25A peak rating).

I might try it if driving a 16R load that can handle in excess of 1.2KW on program material.
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Old 9th January 2008, 02:51 PM   #4
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Thank you for the quick replies!

As they are bridgable, can you clue me in as to which two speaker binding posts result in the bridged (mono) configuration? There is not information about this on the amps themselves.

I'm aware of the power of these puppies, but I love to have tons of headroom. I am using a set of Infinity SM125's right now, but have a set of Paradigms inbound.

I am using a line conditioner by PowerVar to power the units. Hopefully this will temper any AC irregularities that may come about.

Thanks again for the sage advice!
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Old 9th January 2008, 04:55 PM   #5
anatech is offline anatech  Canada
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Hi AltheaToldMe,
Quote:
As they are bridgable, can you clue me in as to which two speaker binding posts result in the bridged (mono) configuration?
The two "positive" speaker terminals.

Quote:
I'm aware of the power of these puppies, but I love to have tons of headroom.
You already have excess headroom. I don't think any amp sounds good in bridge mode. This effect varies with the amp. Remember that your damping factor just got cut in two, and that is not the entire reason for the difference in sound.

Quote:
I am using a line conditioner by PowerVar to power the units. Hopefully this will temper any AC irregularities that may come about.
That is the very worst thing you can do! Do not run these Carvers through anything. Use really good quality outlets rated at 20 amps minimum. Wire each amp directly to the breaker panel directly, and on the same phase. Nothing ever gets put between a high power amplifier and the AC supply.

Think about this. Carver amps chop up the incoming AC waveform. What possible good would anything do here? All that will happen is that your voltage drop will be much worse if you use any conditioner no matter what that manufacturer says about them.

-Chris
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Old 9th January 2008, 06:39 PM   #6
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Points well taken. I really appreciate the advice.

While I am still here, do you have a listing of the specs for the PM 1.5's? I'd love to know.

Also; What would be a couple of good tip for PM on these. Anything in particular to pay attention to as far as components reaching end of life?

I'd like to buy you a beer for your help. Perhaps wine?
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Old 9th January 2008, 06:55 PM   #7
anatech is offline anatech  Canada
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Hi AltheaToldMe,
I think it was rated at 450 WPC into 8R. I never bothered trying to remember that stuff. Besides, the power is so high that it doesn't matter and the ability to deliver that amount of power hinges on the AC supply at those levels. I'm pretty sure the specs are out there. I can tell you that the supply rails were spec'd at 125 VDC, plus and minus. I normally set them for 118 VDC as they tend to creep up over time. That should send chills up your back.

The filter capacitors on the first two tiers will be degraded by now for sure. There are some resistors that tend to overheat on the power supply PCB as well. Standard solder joints and the fan bearings need lubricating. Blow the dust out. The rest depends on how hard a life it's lead. You may or may not have other thermal problems.

Lastly, these are different amps than most. You need a real Carver technician to work on them. People who are only sure they can fix them will cause damage.

Well, I'm in Canada. So it's a long way to fire a beer, but thank you. Why not send some $ to the site instead. It will go to help more people.

-Chris
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Old 10th January 2008, 10:24 AM   #8
Bigred is offline Bigred  Canada
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Give careful consideration to Chris's comments. FWIW forget about bridging. As far as specs: 450WPC@ 8R 600WPC@ 4R 1200W bridged. If you decide to bridge then ***No loads below 8R bridged*** FYI the M-1.5 and PM1.5 pro amp are essentially the same amps.
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Old 10th January 2008, 03:45 PM   #9
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I'm with Chris on this one - don't even think about trying to use carvers in bridge-mode!

you'll just end up with dead speakers and possibly dead carvers.

I don't agree with the power conditioner discussion.
Here in the UK, our mains frequency is 50Hz, the carvers were designed for 60Hz operation.
The result over here is that the power supply runs out of power a little early so we don't use them on bass bins.
There is no thermal sensor in the transformer windings so the amp is prone to overheated windings - smoke and a smell of urine !
The chokes between the inlet and the triac are a little on the flimsy side so the carver 'carves up' the mains.
(you get a dimmer-type buzz picked up around the system).
We're using industrial triac surpressors (30A choke in a can with class X and Y capacitors) wired back-to-front (like you would on a washing machine, because the interference is generated on the load side).
we use 1 per amp - its a little bulky but stops the famous 'carver buzz' dead.
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Old 11th January 2008, 09:32 PM   #10
anatech is offline anatech  Canada
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Hi AudioSystemsEng,
Quote:
Here in the UK, our mains frequency is 50Hz, the carvers were designed for 60Hz operation.
I can't see that happening. What is more likely is that the added resistance from this ....
Quote:
We're using industrial triac surpressors (30A choke in a can with class X and Y capacitors) wired back-to-front (like you would on a washing machine, because the interference is generated on the load side).
is causing the line voltages to sag badly when the Carver attempts to grab a ton of current.
Quote:
There is no thermal sensor in the transformer windings so the amp is prone to overheated windings - smoke and a smell of urine !
The reason the transformer might smoke is the - voltage drop created by the filter!!!! Carver amps have very good amplifier protection, but it wasn't designed to be used with high resistance power supplies. When the voltage drops, the regulation circuit requires the amplifier to draw more current (just like a standard switching supply) to compensate.
Quote:
The chokes between the inlet and the triac are a little on the flimsy side so the carver 'carves up' the mains.
The chokes are not going to deal with the chopped sine or distortion. They are there to filter out RFI. I can't say as I've ever really noticed them actually.
The Carver power supply uses a "transformer" designed to work on current pulses. It will saturate on a normal sine wave input.

-Chris
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