Hafler XL-600.....The Eviction Notice Amp
- Thread starter Son-of-Vere
- Start date
Check the oil ?
mondialfan
Well-Known Member
I have an XL600 that I bought from the original owner locally about 7 years ago. Its a very nice sounding amplifier with power to spare. I've owned earlier model Hafler's and a later Transnova 9300 and I feel the XL600 is the best of them. I'm using it to drive my Acoustat Spectra 22's so well over 500WPC on tap while driving those panels. See the included 4 & 8 ohm output power charts, quite good distortion for a heavily P2P wired amp design from the late 80's if you ask me. I've done a little work on mine, recapped the driver boards and high voltage front end PS located on the DC protect board. One of the best things I did for sound quality IMO was eliminating the rear panel speaker fuses. My take on this is that you already have DC fuses for the rails and a DC protect relay,,,, do you really need another resistance (speaker fuse) inline with the output? NO! Also carefully open the relay housing and lightly burnish the relay contacts.
Son-of-Vere
Super Member
Folded out the board to do the recap.
All tuned up.
Nice work, Carlos.
Fan date, probably a 1990 amp.
Just before the lid goes on. I cant put it in the rack yet as it has a glass shelf and I don't want to put this boat mooring on it.
This must have been a custom extrusion for this heat sink.
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Son-of-Vere
Super Member
OK, had bad photo, damn phone. Will try to get a shot of the recapped board later. Been listening to it for a couple of hours, and I can't believe the difference. Much cleaner and more detailed now, I'm having a hard time believing it's real, and not just psycho-acoustics.
Dayum, I half expected to see a fan belt in there!
Son-of-Vere
Super Member
Well, that was the first plan so I could get the DC offset under control. But I cheaped out and went with just a "normal" recap of the original boards. That XL circuitry also requires careful calibration, something I really don't want to try.
Now that this thread has been brought to the surface, I might as well add this update. I've currently updated my speakers to emulate the ESS AMT 3. The woofers I have in my possession currently are 4 ohm. So in reality I'm running a 2 ohm load. This amp will do this all day and not even get warm. I'd recommend this amp for running odd loads even if you don't plan on using all its power (I sure don't!)
Stacked Advents come to mind.........
Stavro
Active Member
Try muffin fan filters on the air inlets on the side vents (intakes).IMO design is quite genius.. fan generated core cooling in the box. could even add a simple custom dust filter in front of the fan if necessary.
Stavro
Active Member
A V/16 actually.
Stavro
Active Member
Well, the rail fuses are 10amps. Each channel has 2. So doing the math, you are fused at 20 amps per channel. If you figure it maxes out at 85volts, that means it fuses at 1700 watts per channel. It just might be a smidge above what your speakers can take. Just thinking.
mondialfan
Well-Known Member
Stavro,
Why have both DC rail + speaker protection fuses in series with each other not to mention a DC protect relay too as in the XL600? It was common 30 - 40 years ago but it no longer is and its not because modern amps are incapable of frying the speakers attached to them. Check out the back of a modern Krell, Bryston or even the later Hafler Transnova 9303/9505 amps, no speaker fuses just DC rail fuses.
Why have both DC rail + speaker protection fuses in series with each other not to mention a DC protect relay too as in the XL600? It was common 30 - 40 years ago but it no longer is and its not because modern amps are incapable of frying the speakers attached to them. Check out the back of a modern Krell, Bryston or even the later Hafler Transnova 9303/9505 amps, no speaker fuses just DC rail fuses.
Stavro
Active Member
That may be the case for them but my hafler 220 fried my Spica’s and my KLH’s. My 35 watt per channel tube rig - fine - no output fuses. I prefer not repairing my drivers monthly. It is cheaper to replace a fuse. That said, I admire your guts and I am curious as to the sound quality.
Why is a modern amp incapable of damaging a speaker? Is the wall voltage not the same? Is physics not the same? Besides, this amp is not recent vintage.
mondialfan
Well-Known Member
I believe you misunderstood my statement on the power output of the modern amp.
Protection fuses are not going to save your speakers in a lot of instances. You can easily generate enough DC voltage on the output of a failing amp to fry the speakers connected to it but not blow the rail or speaker fuse.
Also a 35W amp is very capable of frying a much higher power rated set of speakers. Drive any amp into clipping (SS more so than tubes) and you can damage the speakers connected to it.
Its really not guts its just being intelligent with the volume knob. If the speaker's sound like they're under distress then turn the volume down. I've had my XL600 connected to very low power rated speakers. I've got a set of 75W max rated bookshelves that were connected to it for extended periods with no issues.
Protection fuses are not going to save your speakers in a lot of instances. You can easily generate enough DC voltage on the output of a failing amp to fry the speakers connected to it but not blow the rail or speaker fuse.
Also a 35W amp is very capable of frying a much higher power rated set of speakers. Drive any amp into clipping (SS more so than tubes) and you can damage the speakers connected to it.
Its really not guts its just being intelligent with the volume knob. If the speaker's sound like they're under distress then turn the volume down. I've had my XL600 connected to very low power rated speakers. I've got a set of 75W max rated bookshelves that were connected to it for extended periods with no issues.
Stavro
Active Member
You are right - nothing beats good judgment.
Funny thing is that I fried my speakers when the 220 had a bad rca input connection on the right side. It is old after all. The 5amp fuse funny enough couldn’t save the drivers - the intermittent connection caused the amp to spike. Now I have 1.5 amp fuses in there. I also fixed the connection as well of course.
Binkman
Lunatic Member
Well you have to include unit consumption watts but still damned good 6-800w with load. one hell of a big block party.
This time I booked the threadl
Lke I said frigging genius..
Usually what burns your speakers isn't dc it's a component failure that shorts the rail voltage and massive current discharge another factor is cheap coils over driven, plus noted crap connections.
Son-of-Vere
Super Member
Quick update, amp is still going strong, still sounds good, and still under that 2 ohm load.