New to me Hafler XL-280

Ealyb11

Ealyb11

Well-Known Member
Well I just swapped out my Adcom GFA-555II for this pristine 1 owner since '89 Hafler. Less power but I wasn't using all that juice for my Paradigms. About 5 songs into listening...it's different. Not bad, initial impressions would describe it as warmer and a tad more laid back up top, with a slight improvement of lower end. Combined with the laid back paradigms it makes a very listenable combo. It's certainly more reasonable sized than the almost-the-size-of-my-room Adcom(ok that's an exaggeration).
I think I will enjoy it though. I am still hunting for a pre amp to replace my VSX9500s that is holding that spot currently.
Is there anything I should know about these amps? Modifications? Things to watch out for? Etc...
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Is the 280 the pro version of the 220? There are mod options for sure. Try a tube pre amp!
 
Okay... First question. I tried to crank the volumn a bit with my paradigms, and the left channel of the Hafler toasted it's fuse. Switched the right channel over and it smoked that one too. I was at maybe 1/3 volumn on my pre amp... Very odd. Hafler is also getting pretty warm compared to Adcom.


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Just put in 3 amp fuses up from the 2 amps that were in it. Seems okay now though I think the Paradigms woofers are about done.
Should I be concerned about it blowing the left channel twice like that?

Also, is this amp 4 ohm capable ? I would assume since its Bridgeable it is....but I can't find anything to back that up.

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There's a lot to like about the XL-280. Given the age, however, any sonic characteristics you're hearing are not likely the way it came out of the box with.

Firstly, on the popping of fuses, if the speakers are closer to 4 ohms than 8 ohms, this will likely account for the fuse size. Upping to a 3.0 amp fast blow should be ok unless there's a problem with one of the speakers or the connecting wire.

The XL-280 is a dual power supply arrangement. That is, there are 2 separate power supplies that share a common power transformer. This means that there's little to affect one change from the other because of that isolation.

Back to the sonic characteristics, there are a number smaller electrolytic caps on both the power supply board and both of the driver boards that could bear replacement. Its not many, though. There's a guy on eBay selling replacement kits for this, if you or a friend are willing to get in there and do it.

I've done this with both my XL-280 and its bigger brother, the XL-600. I didn't use the eBay guy's stuff though as I already had the parts in stock.

However, my recommendation to you is to get a better preamp first. Others may provide valid arguments but I prefer the older 70s gear I once worked on to the newer gear.

Yep, I'm old school!

Cheers,

David
 
So excuse my ignorance, but how does the 4ohm speaker versus an 8ohm cause the fuse to go? And only on one channel...
This amp is 4ohm capable correct? I only ask because most of the speakers I have or I am keeping an eye out for are 4 ohm.


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200 watts per channel at .1%thd 4ohm, not sure on your fuse problem, I was running two sets of Infinity's on mine and never had a fuse problem. Buy the way, didn't baby the amp, opened a voice coil on one for my speakers and it never quit or popped a fuse.
 
Ok, let's do some simple math with 2 assumptions: That the speaker impedance is completely resistive and there is a steady state signal driving the amp. Both aren't the case in actual use but they'll get us close enough for the task at hand.

So, the formula for Power is P = Current squared * resistance, where P is in watts and R is in ohms. We can solve for Current by rearranging the formula to be the square root of (P / R). Current will be the value of the fuse.

The XL-280 is rated at ~140 wpc, so we'll use that for P. So plugging in the values:

An 8 ohm speaker @ 140 watts input will have ~4 amps flowing through it.
An 4 ohm speaker @ 140 watts input will have ~5.9 amps flowing through it.

Remember, this is for pure DC current. AC current, which is what is really passing for audio work, gets bit more complex to calculate but those numbers will come close.

The takeaway, here, is that you are conservatively rated running a 2 or 3 amp speaker fuse in the Hafler - or any other amp or that power. Fuses and current are not brand-specific!

I think you can draw your own conclusions from here.

Cheers,

David
 
Ealyb11 said:
Just put in 3 amp fuses up from the 2 amps that were in it. Seems okay now though I think the Paradigms woofers are about done.
Should I be concerned about it blowing the left channel twice like that?

Also, is this amp 4 ohm capable ? I would assume since its Bridgeable it is....but I can't find anything to back that up.

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The Hafler XL series is stable well below 2 ohms. The Hafler literature of that time period stated that the XL's were designed to drive ANY speaker produced at that time. This included the Apogee Scintilla and their 1 ohm load which were considered back then to be the toughest load for an amp.

The amps run hot because they have a fairly high level of idle bias current. You can always download the manual and if you know how to run a multimeter you can check/adjust the bias current.
 
I don't know, but as the saying goes, it's never too late to learn.

Appreciate the math formula. Surprisingly I understood what you were saying. I also checked my Adcom and found it has 4 speaker fuses, versus the XL's 2. I'll go out on a limb and say that makes a difference...


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And greetings to you in Greenville. I used to work at a stereo shop in the 70s there. Went to music school at ECU, too.

Cheers,

David
 
You know my dad bought a system here in the late 70s from a stereo shop. I think it was between memorial drive and Greenville blvd on a side street. ESS speakers with a JVC Turntable and receiver. I remember the speakers as a kid. They had the Heil tweeter in them I believe. They left long ago but my dad still runs the JVC. It has never missed a beat in all these years.


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They'll be speaker fuses - or better be. That was the calculation being made was for the speaker fuses.

Cheers,

David
 
Ealyb11 said:
You know my dad bought a system here in the late 70s from a stereo shop. I think it was between memorial drive and Greenville blvd on a side street. ESS speakers with a JVC Turntable and receiver. I remember the speakers as a kid. They had the Heil tweeter in them I believe. They left long ago but my dad still runs the JVC. It has never missed a beat in all these years.


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That would have been Pair Electronics - Percy Pair was the owner's name.

Cheers,

David
 
Ealyb11 said:
Just put in 3 amp fuses up from the 2 amps that were in it. Seems okay now though I think the Paradigms woofers are about done.
Should I be concerned about it blowing the left channel twice like that?

Also, is this amp 4 ohm capable ? I would assume since its Bridgeable it is....but I can't find anything to back that up.

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Click to expand...

It's more than 4 ohm capable. You can run it into a dead short with tin foil around the fuses and it will shut down from overheating before it will do any damage. It's rated at 360 watts into 2 ohms and 325 watts into 1 ohm.
You need to check your bias. They went cheap on bias pot quality.
 
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