Lamps
uhm...
This is by far the easiest solution. Tried and tested.
Well, 300 very eco unfriendly Watts seem to be in dire need of being got rid of...
(is that even a sentence?)
uhm...
This is by far the easiest solution. Tried and tested.
Well, 300 very eco unfriendly Watts seem to be in dire need of being got rid of...
(is that even a sentence?)
I hear you, but bulbs aren't available here anymore. And it looks like the carnival. Liberacy's approach to attenuation.
By the way, in terms of resistors I can keep it under 10 bucks. If you're just willing to solder an awful lot.
Thanks/regards
Guitarski
By the way, in terms of resistors I can keep it under 10 bucks. If you're just willing to solder an awful lot.
Thanks/regards
Guitarski
Carnival it may well be. One wonders when they will clamp down on valves...
I don't live in the Netherlands, but a quick search came up with this link.
http://www.lighting.philips.com/pwc...ts/documents/automotive/24V_wlfwf_2011_en.pdf
Available at these fine stores:
http://www.philips.nl/c/locators/re...UMER&cityPostalCodeUsed=amsterdam&language=nl
A few of these should do it, and save you from worrying about the heat. You might light up the neighbourhood with your E-flat but worse things happen....
I know. Truck lighting in fact. 24V Truck lighting is exactly what's required for the kind of impedance you're looking for. But you clearly have your mind set. Bowing out.
Years ago I bought a carton of 300W 120 V incandescent lamps for some 'brilliant' idea I had. I never got the mogul sockets as I didn't like the price...I probably should before they are 'unobtanium'. Soldering wires directly to the lamp base is possible, but not a good mounting method ;O(.
Incandescent (thermionic) light bulbs may be politically eco-hostile, because they are visible. Resistors could be the dark side ('Dark bulbs')...still wasting energy as heat...no more friendly than the lamps...but at least there are no resistor police like the 'dim bulbs' in many political positions.
I guess it depends what audio forum you post in...there MAY be resistor police out there. "You can't use wirewound...there oughta be a law!"
Incandescent (thermionic) light bulbs may be politically eco-hostile, because they are visible. Resistors could be the dark side ('Dark bulbs')...still wasting energy as heat...no more friendly than the lamps...but at least there are no resistor police like the 'dim bulbs' in many political positions.
I guess it depends what audio forum you post in...there MAY be resistor police out there. "You can't use wirewound...there oughta be a law!"
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Hey Jacques. Resistors make me feel I know what I'm talking about. Bulbs may be for those that do. So you could be right, but you may be slightly (or massively) over-qualified for this thread. Sorry you're bowing out, though.
That's also an issue. Were to leave them.
Eco-friendlyness is an issue in that bulbs are unobtanium at your local supermarket nowadays. When did your wife last ask you to go get her a pack of resistors?
That's also an issue. Were to leave them.
Eco-friendlyness is an issue in that bulbs are unobtanium at your local supermarket nowadays. When did your wife last ask you to go get her a pack of resistors?
Maybe that came across a bit harshly. I mean I'm backing off with my argument. Resistors might even be more fun.
Quote: "Soldering wires directly to the lamp base is possible"
PCB?
Quote: "Soldering wires directly to the lamp base is possible"
PCB?
These beasts:
Philips 143164 - 300/IF PS35 Light Bulb at eLightBulbs.com
My wife wouldn't ask me for resistors...she wouldn't want to know how many are in the basement, and I wouldn't know the answer.
Only time she was impressed with colored parts from the basement was when a 3D movie was announced in advance on TV, with plastic 3D glasses available in TV Guide magazine...which sold out...so she was agitated there were no 3D glasses available anywhere.
I had some optical color filter samples from Rosco or someone like that..I picked out a red and a blue one and we taped them onto a pair of her glasses and she watched it successfully.
I think I had the L-R reversed, par for me...
Philips 143164 - 300/IF PS35 Light Bulb at eLightBulbs.com
My wife wouldn't ask me for resistors...she wouldn't want to know how many are in the basement, and I wouldn't know the answer.
Only time she was impressed with colored parts from the basement was when a 3D movie was announced in advance on TV, with plastic 3D glasses available in TV Guide magazine...which sold out...so she was agitated there were no 3D glasses available anywhere.
I had some optical color filter samples from Rosco or someone like that..I picked out a red and a blue one and we taped them onto a pair of her glasses and she watched it successfully.
I think I had the L-R reversed, par for me...
Murray, at 300W the resistance would be around 50 Ohm for this lamp, which means the amp, even if it likes it, won't want to drive it that hard. (Which may even be an advantage.) At low power, though, it would have a close to 8 Ohm resistance. Who knows? Might be just the ticket if the amp survives the high impedance...
Speaking of high impedance, I have always assumed that a tube amp will run at an impedance higher than its rating, apart from dynamics issues. How do you see that?
Thanks/regards
Guitarski
Thanks/regards
Guitarski
True, but depends on the amp. Speakers have highly variable impedance - from under 4 Ohm to over one hundred Ohm in it's frequency range. Amps with feedback (such as yours, doubtless) are prone to either increased gain or oscillation when operated with a too high impedance load. This could destruct screen grids and transformers, ultimately. Usually only happens when the amp is driven hard. "High" impedances like 16 Ohm usually present no problems and may even work better. But one treads on thin ice using 50 Ohm loads, especially with expensive equipment. Listening to the output or watching output tubes closely would usually give clues as to whether the amp is unhappy (glowing grids, unusual distortions). I'd venture that one should stay under, say, 20 Ohm, if you want to overdrive an amp. No clues in the manual? It would be highly variable IMHO. (I'm no expert with push-pull BTW. Just my 2c...)
You mean, it isn't class A?
It would be nice if I could run a 4 ohm amp on an 8 ohm cab. Most bass cabs are 8 ohm (AFAIK) and I don't want to be restricted to 4 ohms. Reading your post I take it that 8 ohm is ok.
<RANT>Are you kidding? This is a trend that Microsoft started: "Customer service just costs us money, let the customer ask for help from other customers". Netscape also did its part: "No company can afford to pay its programmers", so maybe it's a 90s thing. Anyway, you get a quick start guide at best. For my DAW I bought a printed manual.</RANT>
I'd say so. From the Bugera site: "Impedance switch (2 and 4 Ohms) to match virtually any speaker cabinet." Sounds like it might be OK even by them.
As to Class A (I'm assuming you weren't joking...) - the amp uses 3 pairs of 6550, and it seems some elaborate mechanism to extend life and bias even unmatched tubes. It's push-pull class AB1, if I had to say. That's the only way according to the 6550 data sheet to get to 300W. Ultralinear would give 210W IIRC and class A1 only 120W.
So, there would be feedback, almost certainly, and the kind which likes very high impedance less than a dead short. Almost the only way to know how far one can go is to check very carefully how it responds to high impedance, and to not stray too far from 2 or 4 Ohms (after insuring the amp). I was assuming, wrongly, that the amp had an 8 Ohm tap. Even so, I think 8 Ohm would be fine, at a slight loss of volume. Even maybe 16 Ohm, but it would probably be pointless.
As to the dummy load... Do you have a 120V 1500W kettle? That should give you around 9 Ohm, never dropping below 2 Ohm. Plus you can have a coffee every so often.
As to Class A (I'm assuming you weren't joking...) - the amp uses 3 pairs of 6550, and it seems some elaborate mechanism to extend life and bias even unmatched tubes. It's push-pull class AB1, if I had to say. That's the only way according to the 6550 data sheet to get to 300W. Ultralinear would give 210W IIRC and class A1 only 120W.
So, there would be feedback, almost certainly, and the kind which likes very high impedance less than a dead short. Almost the only way to know how far one can go is to check very carefully how it responds to high impedance, and to not stray too far from 2 or 4 Ohms (after insuring the amp). I was assuming, wrongly, that the amp had an 8 Ohm tap. Even so, I think 8 Ohm would be fine, at a slight loss of volume. Even maybe 16 Ohm, but it would probably be pointless.
As to the dummy load... Do you have a 120V 1500W kettle? That should give you around 9 Ohm, never dropping below 2 Ohm. Plus you can have a coffee every so often.
I know it isn't A, but assumed that to be why you mentioned oscillation.
Apparently they see lots of 2 Ohm cabinets, I wonder where.
And now for the big OOPS!
From the Bugera knowledge base:
I can't limit myself to 4 ohm cabs, so if I connect an 8 ohm dummy (besides the 8 ohm cab), is this going to affect the sound, you reckon?
I asked Bugera support if dummy loads were a good way to go, but they didn't specifically answer that. Just that the're dead set against tube pulling and recommend attenuators. I've read some guitar forums about that, but guitarists are underwhelmed, because they say attenuators do badly affect the sound.
However, Jacques, the greater issue is that overnight Bugera reduced the price of my amp by 25%, that's a freaking 157 euro.
How do you know that and why doesn't it sound like an Ampeg (rhetorical question)?
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Hi,
I must confess I'm pooped. Just finished work and it's almost midnight. Sorry if I speak rubbish.
Class A? Oscillation? Thought they were rock solid..
I'd venture that an 8 Ohm cab (all other things being equal) won't sound much different from a 4 Ohm one. A dummy load is much more stable a load compared to a loudspeaker.
That said, tapping off the loaded output would convey the distortion/sound signature of the valve amplifier (when it distorts) but one would obviously not have the same output as one would have with the speaker load connected. This should be a relatively minor difference as an amplifier like this is largely a voltage source, not a current source; in other words the amp tries to maintain a specific voltage, irrespective of the load (within limits!). A current source amplifier (not an ideal one, an approximate one) has non-negligible output impedance (it is as if there's a resistor in series with the output; a perfect current source acts as if there's an infinite resistance in series with the output, but this is a theoretical construct and best ignored here) and its output voltage DOES depend on the load impedance.
What I am saying: (and I apologise if I say things you know or have chosen to forget) if the amp doesn't blow up it should sound almost the way it normally sounds. ALMOST.
What I'm really saying: TRY IT OUT, on a load that doesn't cost lots of money and is sensible/close to a speaker in its characteristics - but only a little, watching very closely for anything going wrong, listening to the output over phones. Just for a second at first, then more, if all's ok.
Everything affects sound: sometimes badly, sometimes inaudibly, sometimes even positively. It might sound worse or better on the dummy load - and taste comes into it.
I don't much like tube pulling either. Might work, but I just don't like it.
I have a personal rule - never to check prices after I've bought something. I doesn't work, but it's my rule all the same.
I must confess I'm pooped. Just finished work and it's almost midnight. Sorry if I speak rubbish.
Class A? Oscillation? Thought they were rock solid..
I'd venture that an 8 Ohm cab (all other things being equal) won't sound much different from a 4 Ohm one. A dummy load is much more stable a load compared to a loudspeaker.
That said, tapping off the loaded output would convey the distortion/sound signature of the valve amplifier (when it distorts) but one would obviously not have the same output as one would have with the speaker load connected. This should be a relatively minor difference as an amplifier like this is largely a voltage source, not a current source; in other words the amp tries to maintain a specific voltage, irrespective of the load (within limits!). A current source amplifier (not an ideal one, an approximate one) has non-negligible output impedance (it is as if there's a resistor in series with the output; a perfect current source acts as if there's an infinite resistance in series with the output, but this is a theoretical construct and best ignored here) and its output voltage DOES depend on the load impedance.
What I am saying: (and I apologise if I say things you know or have chosen to forget) if the amp doesn't blow up it should sound almost the way it normally sounds. ALMOST.
What I'm really saying: TRY IT OUT, on a load that doesn't cost lots of money and is sensible/close to a speaker in its characteristics - but only a little, watching very closely for anything going wrong, listening to the output over phones. Just for a second at first, then more, if all's ok.
Everything affects sound: sometimes badly, sometimes inaudibly, sometimes even positively. It might sound worse or better on the dummy load - and taste comes into it.
I don't much like tube pulling either. Might work, but I just don't like it.
I have a personal rule - never to check prices after I've bought something. I doesn't work, but it's my rule all the same.
There's a big mix-up, here, let's get it straight.
Class A will not (easily) oscillate. Never mind.
Funk1980 suggested that the tubes "see" the load and wil react differently to a dummy than to a speaker. We'll see. I ordered 30x 160 ohm (@10W) resistors so that's going to be one h+ll of a dummy. Actually, it's just the kind of project that will likely go wrong, since there are several parameters I'm just taking a guess at, such as heat, and probably more that I'm not aware of. Thinking about how to channel 200W through the dummy, I suddenly realize why there are dedicated speaker cables. Much more load than instrument cables!
I like your phlegm. But Bugera says that transformer and tubes will suffer under an inappropriate load. That would be nice info for in the Quick Start Guide, which is now a Quick Death Guide, rather.
No phlegm. That would be unfair seeing it's not my amp. Thus: sensible. Which is what you're doing it seems.
Funk1980 is correct in saying that. The question therefore is more 'how' than 'what' - and, being a musician, there's only one way to know. My fear: when one quite likes something and it changes, one usually doesn't any more. Therefore: inexpensive.
30 resistors: maybe you won't even need a fan on them I've found.
Funk1980 is correct in saying that. The question therefore is more 'how' than 'what' - and, being a musician, there's only one way to know. My fear: when one quite likes something and it changes, one usually doesn't any more. Therefore: inexpensive.
30 resistors: maybe you won't even need a fan on them I've found.
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