Stavro
Active Member
Question - to turn off at night or when I go to work or should I let it sit on?
Hafler XL-600.....The Eviction Notice Amp
- Thread starter Son-of-Vere
- Start date
mondialfan
Well-Known Member
I would absolutely turn it off at night after use. Properly biased the XL600 will draw 150 watts or more from the wall when idling and even more if overbiased. Just turn it on a half hour or so before you want to listen to it to give it time to warm up respectably. The difference in sound quality between a half hour warm-up and leaving it on permanently is hard to justify in my opinion. Personally I cannot tell the difference.
Stavro
Active Member
I am more concerned with the power surge on startup more than anything.
mondialfan
Well-Known Member
I'm more concerned about the power surge that comes when its operating especially when I'm not around. My fathers house has been hit by lightning twice over the years. Yeah I know lightning does strike twice sometimes... Both times it destroyed various TV's and other electronics in the house. He now unplugs his entertainment center every time he leaves the house for an extended period.
I do the same for my vintage electronics rack in my dedicated listening room. When I'm done listening the whole thing gets unplugged from the wall. Too many thunderstorms roll through here for me to feel comfortable with it plugged in. Many of my electronics have components inside that are very hard or very expensive to replace.
If you're worried about startup surges install an NTC inrush protector, I use an SL22 2ohm 18Amp rated one in some of the Acurus amps I modify for people and it would be a good one for the XL600. Better yet, put a slow start circuit in. Slow start circuits are not hard to build and there's plenty of room inside of the XL-600 for one. Realistically though the 2 ohm inrush will do a good job and there's a perfect place to mount it in the XL-600, the incoming terminal strip has several open eyes that are perfect for it. It would probably take you longer to remove the cover and heat up the soldering iron than it would to install the inrush protector.
mondialfan
Well-Known Member
Well I spoke too soon about adding inrush protection my 600 is sitting in my office so I removed the cover. There is a CL-100 inrush protector hidden underneath the heat sink tunnel. It is not shown on the XL600 schematic, but it sits right between the two thermal breakers TB301 & TB302, it actually connects the two breakers. I was having a hard time pulling up the datasheet for the CL-100, but it measures out at 0.5ohm cold.
Stavro
Active Member
Well that makes me feel better. They thought of everything I guess.
Son-of-Vere
Super Member
There is no way in hell I would leave that toaster oven on 24/7. I usually play something I'm less enthusiastic about first, it does take about 30 mins to get going, and my woofers are the same way.
I was getting ready to say "why would you want to add another inrush protector?" but it looks like you got that base covered. I also switch it on thru a triac, so I'm not smoking any switches.
I was getting ready to say "why would you want to add another inrush protector?" but it looks like you got that base covered. I also switch it on thru a triac, so I'm not smoking any switches.
Stavro
Active Member
I see there is a data sheet for the CL-101 at 0.5ohm. Must have been updated.
mondialfan
Well-Known Member
No the 4 - 16 Amp Current range they have listed in the datasheet is the expected operating current range for the thermistor. That is dependent on the load you attach to it. There's a lot more inrush than 480watts at startup in the XL-600. The thermistor is only .5ohm max when cold, 120V across .5 ohm....... The transformer of course has some resistance to it as well, but you can expect the inrush to exceed 1000W for several mS. The only way to minimize that is to install a slow start, but based on nearly 30 years of operation it looks like the .5 ohm thermistor is enough. I haven't seen where people are having to replace the mains fuse, power switch or shorted bridge rectifiers which are a few common signs of excessive inrush currents. I believe you're alright!
Stavro
Active Member
Dumb question - why does it put out over twice the power when in bridged mono mode? Is it due to a thermistor on the speaker grounds?
mondialfan
Well-Known Member
It should ideally be 4X the amount of power in bridged mode if everything is ideal, i.e. power supply is up to the task and enough output devices to pass the current, etc.
No its not due to a thermistor.
In bridged mono mode the two channels are combined to drive a single load from opposite sides of the load. One channel is driving the positive half of the signal and the opposite channel is driving the negative half of the signal. In a standard non-bridged config only the positive post is being driven the opposite post is normally at ground potential. Because both speaker posts are being driven in bridged mono mode each post is capable of seeing full voltage swing of the respective channel driving it. In the case of the xl-600 lets say for this example its capable of delivering 50V rms across an 8ohm load in stereo mode before clipping. In bridged mode this will become 100V rms because each side of the load is being driven, +50V rms on the pos side and - 50V on the neg side.
P = E^2/R so
50V rms into an 8 ohm load = 312.5W
100V rms into an 8 ohm load = 1250W
The XL-600's transformer runs out of steam and keeps it from being able to develop that much power.
Stavro
Active Member
Thank you for explaining that. Is the output 50V? The service manual if you can call it that says the transformer is putting out +90V and -90V to the driver boards. Could it have 40V of loss?
I bought it used a couple of months ago - and absolutely love it. I also have a DH220 in a different room and a bunch of newer tube gear, but this is much more fun (and sounds amazing). It seems virtually indestructible. I couldn’t be happier.
mondialfan
Well-Known Member
My 50V number was rms. The rails being at +/- 90V means it has the capability of driving 180v Peak to Peak if the rails don't sag under load (which they will), 180Vpp = 63.6Vrms. The +/- 90V shown in the manual is with a minimal load, the transformer secondaries will drop substantially once a heavy load is put on it, down to probably +/- 80V or less.
50V rms = 141 Vpp = 312W into 8 ohms. I chose that number because its close to the output rating of the XL600. Mine usually measures around 350w @ 8 ohms with both channels driven.
50V rms = 141 Vpp = 312W into 8 ohms. I chose that number because its close to the output rating of the XL600. Mine usually measures around 350w @ 8 ohms with both channels driven.
Stavro
Active Member
I get it now. Very much appreciated. Still a huge amount of power for a city apartment.
mondialfan
Well-Known Member
Yes, that's a lot of amp for an apartment for sure.
Stavro
Active Member
I was doing some reading. I measured the voltage at the caps and it is +90v and -90V. I read that according to IEC Type F spec, the rail fuses (each 10A) will have an open time of up to 60min at 150% or rating and 30min at 210% of rating. Theoretically this amp should be able to give peaks at over 1700wpc, and 900wpc for up to an hour - if I am not deaf first, and if the caps have enough juice in them. I have 4ohm speakers. The ability to have this much power in a New York apartment is rather obscene.
"Will you look at dis guy ovah heah? Mr. Reddy Kilowatt. Eh buddy, you gotta permit fah dat?"
Stavro
Active Member
Lol, it’s a rockin’ kind of town!"Will you look at dis guy ovah heah? Mr. Reddy Kilowatt. Eh buddy, you gotta permit fah dat?"
This thread has motivated me to try to resurrect my XL600. It sat in the basement for the last 20 years and was starting to fade before that. Now only one channel produces what I think is diminished output. From an electronics repair standpoint I'm only qualified to remove the cover and say "wow, cool" then put it right back on.
Anyone know where I could send it in North America for a professional rebuild without breaking the bank? I live near Pittsburgh if that matters.
Anyone know where I could send it in North America for a professional rebuild without breaking the bank? I live near Pittsburgh if that matters.