How would a WOPL1000 stack up against a pair of these

JustMike

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Lazarus Short

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There is a lot of excitement at AK over one a fellow in the UK took home from a salvage facility - cheap too - they call it a "scroe".
 
Northwinds

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Yep, that's what prompted the question. I wonder how a WOPL1000 would stack up against a pair of these in 4-8ohm. They look impressive but all the weight. The 700 only weighs 55lbs and puts out about the same power at 8ohms maybe more. Being these are monoblocs, it would require two to equal a WOPL right (at least at 8 ohms)
 
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JustMike

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Northwinds said:
Yep, that's what prompted the question. I wonder how a WOPL1000 would stack up against a pair of these in 4-8ohm. They look impressive but all the weight. The 700 only weighs 55lbs and puts out about the same power at 8ohms maybe more. Being these are monoblocs, it would require two to equal a WOPL right (at least at 8 ohms)
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If both amps (two for the mono blocks) were driving a quality set of speakers say with a nominal impedence load of 8 ohms,
they would probably sound very close in a blind test.
But if the speakers had a difficult load such as Infinity IRS V where the nominal load is 4ohms and can dip lower than 2 ohms,
The mono blocks would be more stable at the same spl.
If you are lucky enough to own the Infinitys, I guess you could probably afford those mono beasts, But
for the money invested in a WOPL amp and a good pair of speakers that the WOPL can drive,
What would be a fair comparison?

Ron, your new avatar.......LMFAO !!!!
 
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You're also talking class A here, if the info is accurate. It would be like sitting next to an oven with it just idling along. Efficiency wise, class A sucks but it should be sonically better than a class B amp.
 
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JustMike said:
Ron, your new avatar.......LMFAO !!!!
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LOL, that picture has a story but you would have to be a Dean Guitar Forum member to appreciate it. The gentleman with the KFC bucket in that picture is a good friend of mine named Jeff. He had an interesting way of making light of things people take too serious and he did it with a good heart
 
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gadget73 said:
You're also talking class A here, if the info is accurate. It would be like sitting next to an oven with it just idling along. Efficiency wise, class A sucks but it should be sonically better than a class B amp.
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The WOPL's are Class A/B. I think the big advantage is for people looking to build a monster PA system, otherwise, these amps can never see their full potential. The WOPL's are hard enough. My little FC 400 overwhelms my CV's... I have yet to experience her at full song

Idling Class A amps run hot but when you open them up with volume, they cool down. I have had a few Class A amps but none of them had enough wattage and headroom to enjoy them at max levels. The Yamaha I had was a great amp but paled in comparison to a WOPL in sonics and delivery
 
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the power efficiency thing is largely why most of them don't have huge headroom. A friend has a Nelson Pass designed class A amp. I think its good for 25 watts a channel, and its pretty much the same size as my PL 700. Nearly the same weight too. I'm a low power guy at heart, so that really doesn't bother me if its paired with the right speakers. With enough efficiency, you can make enough sound at 25 watts that your ears will hurt. My current favorite amplifier is a 25 wpc tubed Bogen amp. The PL is louder, but the Bogen blows it out of the water in terms of straight up sound quality.



The WO board makes the PL output stage run in AB ? Must make a lot more heat that way. I'm guessing fans become a must-have at that point? The stock design is class B according to the service manual and that follows the ~0.4v of bias voltage fed to the base. To get the output stage into AB, I expect you'd need a fair bit more heat sink, and changes to the resistor on the driver to get enough voltage developed across it to get the stage into AB without burning the driver transistor to death.
 
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gadget73 said:
the power efficiency thing is largely why most of them don't have huge headroom. A friend has a Nelson Pass designed class A amp. I think its good for 25 watts a channel, and its pretty much the same size as my PL 700. Nearly the same weight too. I'm a low power guy at heart, so that really doesn't bother me if its paired with the right speakers. With enough efficiency, you can make enough sound at 25 watts that your ears will hurt. My current favorite amplifier is a 25 wpc tubed Bogen amp. The PL is louder, but the Bogen blows it out of the water in terms of straight up sound quality.



The WO board makes the PL output stage run in AB ? Must make a lot more heat that way. I'm guessing fans become a must-have at that point? The stock design is class B according to the service manual and that follows the ~0.4v of bias voltage fed to the base. To get the output stage into AB, I expect you'd need a fair bit more heat sink, and changes to the resistor on the driver to get enough voltage developed across it to get the stage into AB without burning the driver transistor to death.
Click to expand...
My owners manual states clearly that the PL700 is class AB. The complementary output stage may be class B but there is a DC
component applied to bias the output transistors for lower distortion which makes it class AB.
I'll let Joe explain it to you Gadget, I'm just a guy that likes PL amps.
I have been collecting Bogen amps for 50 years and own some of the best ones they made. In fact the Quicksilver amps
are basically Bogen design. The DS265 Bogen tube amp I have has a beautiful sound, one of the best old amps I have ever
heard driving Efficient Speakers. But trying to drive my Dahlquists ,No Way. Thats where the Pl700 blows the Bogen away.
Both great amps, two different animals.
 
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JustMike said:
My owners manual states clearly that the PL700 is class AB. The complementary output stage may be class B but there is a DC
component applied to bias the output transistors for lower distortion which makes it class AB.
Click to expand...

dunno, the service manual for the 700-II with quasi-comp says its class B. They wrote it, not me :) I don't actually have a service manual for a fully comp version. The base voltage just doesn't seem to be high enough to actually switch the output devices on at idle. Turn-on voltage for those big outputs can't be much under a half volt. I didn't bother to dig up a datasheet but I expect its probably somewhere in that 0.2-0.6v bias range that the manual specifies. I might be dead wrong, I'm not a solid state guy at all but thats what seems to make sense to me as I understand it. It would be easy enough to confirm. If there is no voltage drop at all across the 0.33 ohm emitter resistors, then they aren't conducting. Half the reason I got the PL is for the learning it offers. Can't learn to work on solid state gear unless you actually own one to work on.


I have been collecting Bogen amps for 50 years and own some of the best ones they made. In fact the Quicksilver amps
are basically Bogen design. The DS265 Bogen tube amp I have has a beautiful sound, one of the best old amps I have ever
heard driving Efficient Speakers. But trying to drive my Dahlquists ,No Way. Thats where the Pl700 blows the Bogen away.
Both great amps, two different animals.
Click to expand...
The Quicksilver amps are basically a clone of the MO-100a circuit if you're talking about the ones I think you are. I have a pair of MO-100a on my refurb list, though I'm converting them to 6550 or KT88 outputs and just a pair of them vs the original quad. Front end will be a 6AN8 pentode-triode tube. Not my design, a guy much smarter than me already did the research and testing to come up with the schematic. My DS-225 lives in the bedroom and does a wonderful job on the Klipsch KG-4's. I'm picking up a DB-230 soon too, which I haven't decided where that will live yet.
 
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gadget73 said:
the power efficiency thing is largely why most of them don't have huge headroom. A friend has a Nelson Pass designed class A amp. I think its good for 25 watts a channel, and its pretty much the same size as my PL 700. Nearly the same weight too. I'm a low power guy at heart, so that really doesn't bother me if its paired with the right speakers. With enough efficiency, you can make enough sound at 25 watts that your ears will hurt. My current favorite amplifier is a 25 wpc tubed Bogen amp. The PL is louder, but the Bogen blows it out of the water in terms of straight up sound quality.



The WO board makes the PL output stage run in AB ? Must make a lot more heat that way. I'm guessing fans become a must-have at that point? The stock design is class B according to the service manual and that follows the ~0.4v of bias voltage fed to the base. To get the output stage into AB, I expect you'd need a fair bit more heat sink, and changes to the resistor on the driver to get enough voltage developed across it to get the stage into AB without burning the driver transistor to death.
Click to expand...

The only class A is in the V/A stage...on a WOPL or PL...
 
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laatsch55 said:
I think it's somewhere around 10 watts it's class A, Joe would have to put his 2 cents in here.,..
Click to expand...
The class A operation is limited to right around 0 output volts and is conducted by the 10 ohm resistor to the speaker load. The bias voltage is nominally 0.38V and the forward conduction point of the remaining output drivers is 0.65V. Thus the 10 ohm resistor will be delivering under 10 milliwatts of power to the speakers before the main outputs start conducting. Thus the operation is class AB.
 
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