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#1
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try
it on a 12" speaker which is 8 ohms. Jam away? |
#2
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
zyx wrote: I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms. Jam away? You won't do any harm. Graham |
#3
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
zyx wrote: I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms. Jam away? That should be fine, jam away. Its always OK to use a higher ohm value for speakers instead of a lower value on nearly all amps. Patrick Turner. |
#4
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
Despite what you may have seen from a couple of
the know-it-alls on this NG, don't do it. Audiophools rarely stress their gear, and consequently rarely consider what may happen to it when it is operated beyond design parameters - as guitar amplifiers *routinely* are. You risk a condition known as high- tension flyback if you run a tube guitar amp into a higher than rated impedance; this will fry your power tube socket, along with the tube in it. Lower-powered amps are certainly not immune to this, judging by the number of tube sockets I've replaced in Fender Champs and small Gibsons over the years. Get the correct impedance speaker. Lord Valve Expert VISIT MY WEBSITE: http://www.nebsnow.com/LordValve I specialize in top quality HAND SELECTED NOS and current-production vacuum tubes for guitar and bass amps. Good prices, fast service. Authorized dealer for QSC amps, Sovtek/Electro-Harmonix, Behringer, Hammond-Suzuki, Leslie, Rolls, Weber VST, etc.! - Partial Client List - * Derek Trucks (Allman Brothers Band/Derek Trucks Band) * * Meatloaf * Catherine Wheel * Yo La Tengo * Let's Go Bowling * * Kofi Burbridge (DTB) * Tod Smallie (DTB) * Susan Tedeschi * * Roy Pritts (former head, Audio Engineering Society) * * Rob Hyckys (guitarist for Commander Cody) * Waky Amps * * Jamie McLean (guitarist for the Dirty Dozen Brass Band) * * John Pierce (bassist for Huey Lewis and the News) * * Rob Eaton (guitarist for Dark Star Orchestra) * * Detroit Frank DuMont (guitarist, Frank DuMont and the Drivin' Wheels) * * Coco Montoya * Clint Black * Bill McKay * Mojo Watson * Dick Dale * * Fleetwood Mac * Tyrin Benoit * Eugene Fodor * Dale Bruning * * Komet Amplification * Dr. Z * Maven Peal * Blockhead Amps * * Jim Kelley * Balls Amplification * Roccaforte Amplifiers * * Gerhart Amplification * Aiken Amplification * Germino Amplification * * Lots More * NBS Electronics, 230 South Broadway, Denver, CO 80209-1510 Phone orders/tech support after 1:30 PM Denver time at 303-778-1156 - Our 25th Year - VISA - MASTERCARD - PAYPAL - DISCOVER "It ain't braggin', if ya can do it." - Dizzy Dean zyx wrote: I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms. Jam away? |
#5
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
Patrick Turner wrote: zyx wrote: I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms. Jam away? That should be fine, jam away. Its always OK to use a higher ohm value for speakers instead of a lower value on nearly all amps. Patrick Turner. That's nearly all **solid state** amps. The Epi is a tube amp. |
#6
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
In article , Lord Valve wrote:
Despite what you may have seen from a couple of the know-it-alls on this NG, don't do it. Audiophools rarely stress their gear, and consequently rarely consider what may happen to it when it is operated beyond design parameters - as guitar amplifiers *routinely* are. You risk a condition known as high- tension flyback if you run a tube guitar amp into a higher than rated impedance; this will fry your power tube socket, along with the tube in it. Lower-powered amps are certainly not immune to this, judging by the number of tube sockets I've replaced in Fender Champs and small Gibsons over the years. Get the correct impedance speaker. Lord Valve Expert Consider the rated Z is just a nominal figure, and the real Z will rapidly rise with frequency, every amp would be at risk according to your advice. The rated Z is at a bass frequency. if you don't play bass, then its not a relavant issue. greg VISIT MY WEBSITE: http://www.nebsnow.com/LordValve I specialize in top quality HAND SELECTED NOS and current-production vacuum tubes for guitar and bass amps. Good prices, fast service. Authorized dealer for QSC amps, Sovtek/Electro-Harmonix, Behringer, Hammond-Suzuki, Leslie, Rolls, Weber VST, etc.! - Partial Client List - * Derek Trucks (Allman Brothers Band/Derek Trucks Band) * * Meatloaf * Catherine Wheel * Yo La Tengo * Let's Go Bowling * * Kofi Burbridge (DTB) * Tod Smallie (DTB) * Susan Tedeschi * * Roy Pritts (former head, Audio Engineering Society) * * Rob Hyckys (guitarist for Commander Cody) * Waky Amps * * Jamie McLean (guitarist for the Dirty Dozen Brass Band) * * John Pierce (bassist for Huey Lewis and the News) * * Rob Eaton (guitarist for Dark Star Orchestra) * * Detroit Frank DuMont (guitarist, Frank DuMont and the Drivin' Wheels) * * Coco Montoya * Clint Black * Bill McKay * Mojo Watson * Dick Dale * * Fleetwood Mac * Tyrin Benoit * Eugene Fodor * Dale Bruning * * Komet Amplification * Dr. Z * Maven Peal * Blockhead Amps * * Jim Kelley * Balls Amplification * Roccaforte Amplifiers * * Gerhart Amplification * Aiken Amplification * Germino Amplification * * Lots More * NBS Electronics, 230 South Broadway, Denver, CO 80209-1510 Phone orders/tech support after 1:30 PM Denver time at 303-778-1156 - Our 25th Year - VISA - MASTERCARD - PAYPAL - DISCOVER "It ain't braggin', if ya can do it." - Dizzy Dean zyx wrote: I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms. Jam away? |
#7
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
zyx wrote
I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms. Jam away? A bit risky. Anode voltage may rise higher than some parts can cope with reliably. As a general rule, SS amps don't care too much about a higher load impedance, and valves are tolerant of a lower one. cheers, Ian |
#8
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
greg said:
Consider the rated Z is just a nominal figure, and the real Z will rapidly rise with frequency, every amp would be at risk according to your advice. The rated Z is at a bass frequency. if you don't play bass, then its not a relavant issue. Perhaps you might, step by step, check the logic of your argument. Assuming similar characteristics, an 8 ohm speaker will rise to a maximum impedance of twice that of the 4 ohm speaker. An amp designed to be reliable at the maximum impedance of the 4 ohm speaker may not be reliable at the maximum impedance of an 8 ohm speaker. It would be OK if you stuck to bass. cheers Ian |
#9
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
Lord Valve wrote: Despite what you may have seen from a couple of the know-it-alls on this NG, don't do it. Audiophools rarely stress their gear, and consequently rarely consider what may happen to it when it is operated beyond design parameters - as guitar amplifiers *routinely* are. You risk a condition known as high- tension flyback if you run a tube guitar amp into a higher than rated impedance; this will fry your power tube socket, along with the tube in it. Lower-powered amps are certainly not immune to this, judging by the number of tube sockets I've replaced in Fender Champs and small Gibsons over the years. Get the correct impedance speaker. From just a 2:1 change in load impedance ? You jest surely. Having an open on the output is another matter entirely of course. Graham |
#10
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
Ian Iveson wrote: zyx wrote I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms. Jam away? A bit risky. Anode voltage may rise higher than some parts can cope with reliably. Oh puhleeze ! Is that nonsense or what ? As a general rule, SS amps don't care too much about a higher load impedance, and valves are tolerant of a lower one. Tolerant to a point ! I wouldn't advise it. In fact I doubt any valve amps will drive a 1 - 2 ohms load very well, yet many SS amps do it admirably. Graham |
#11
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
Ian Iveson wrote: greg said: Consider the rated Z is just a nominal figure, and the real Z will rapidly rise with frequency, every amp would be at risk according to your advice. The rated Z is at a bass frequency. if you don't play bass, then its not a relavant issue. Perhaps you might, step by step, check the logic of your argument. Assuming similar characteristics, an 8 ohm speaker will rise to a maximum impedance of twice that of the 4 ohm speaker. An amp designed to be reliable at the maximum impedance of the 4 ohm speaker may not be reliable at the maximum impedance of an 8 ohm speaker. Do tell me more about this reliability Ian ! Especially when a speaker's impedance can rise at some frequencies to easily TEN TIMES the 'nominal' figure. By your argument, driving the amplifier at such frequencies will destroy it. It would be OK if you stuck to bass. It would be OK if you stuck to not making stuff up about which you know nought. Graham |
#12
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
"zyx" wrote in message ... I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms. Jam away? Such mixed results. who to believe... who to believe... any links to learn more about it? By the way I already have an 12" 8 ohm speaker so I asked. |
#13
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
GregS wrote: In article , Lord Valve wrote: Despite what you may have seen from a couple of the know-it-alls on this NG, don't do it. Audiophools rarely stress their gear, and consequently rarely consider what may happen to it when it is operated beyond design parameters - as guitar amplifiers *routinely* are. You risk a condition known as high- tension flyback if you run a tube guitar amp into a higher than rated impedance; this will fry your power tube socket, along with the tube in it. Lower-powered amps are certainly not immune to this, judging by the number of tube sockets I've replaced in Fender Champs and small Gibsons over the years. Get the correct impedance speaker. Lord Valve Expert Consider the rated Z is just a nominal figure, and the real Z will rapidly rise with frequency, every amp would be at risk according to your advice. The rated Z is at a bass frequency. if you don't play bass, then its not a relavant issue. Sorry, realworld experience puts the lie to your statement. No offense. LV greg VISIT MY WEBSITE: http://www.nebsnow.com/LordValve I specialize in top quality HAND SELECTED NOS and current-production vacuum tubes for guitar and bass amps. Good prices, fast service. Authorized dealer for QSC amps, Sovtek/Electro-Harmonix, Behringer, Hammond-Suzuki, Leslie, Rolls, Weber VST, etc.! - Partial Client List - * Derek Trucks (Allman Brothers Band/Derek Trucks Band) * * Meatloaf * Catherine Wheel * Yo La Tengo * Let's Go Bowling * * Kofi Burbridge (DTB) * Tod Smallie (DTB) * Susan Tedeschi * * Roy Pritts (former head, Audio Engineering Society) * * Rob Hyckys (guitarist for Commander Cody) * Waky Amps * * Jamie McLean (guitarist for the Dirty Dozen Brass Band) * * John Pierce (bassist for Huey Lewis and the News) * * Rob Eaton (guitarist for Dark Star Orchestra) * * Detroit Frank DuMont (guitarist, Frank DuMont and the Drivin' Wheels) * * Coco Montoya * Clint Black * Bill McKay * Mojo Watson * Dick Dale * * Fleetwood Mac * Tyrin Benoit * Eugene Fodor * Dale Bruning * * Komet Amplification * Dr. Z * Maven Peal * Blockhead Amps * * Jim Kelley * Balls Amplification * Roccaforte Amplifiers * * Gerhart Amplification * Aiken Amplification * Germino Amplification * * Lots More * NBS Electronics, 230 South Broadway, Denver, CO 80209-1510 Phone orders/tech support after 1:30 PM Denver time at 303-778-1156 - Our 25th Year - VISA - MASTERCARD - PAYPAL - DISCOVER "It ain't braggin', if ya can do it." - Dizzy Dean zyx wrote: I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms. Jam away? |
#14
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
Eeyore wrote: Lord Valve wrote: Despite what you may have seen from a couple of the know-it-alls on this NG, don't do it. Audiophools rarely stress their gear, and consequently rarely consider what may happen to it when it is operated beyond design parameters - as guitar amplifiers *routinely* are. You risk a condition known as high- tension flyback if you run a tube guitar amp into a higher than rated impedance; this will fry your power tube socket, along with the tube in it. Lower-powered amps are certainly not immune to this, judging by the number of tube sockets I've replaced in Fender Champs and small Gibsons over the years. Get the correct impedance speaker. From just a 2:1 change in load impedance ? You jest surely. Having an open on the output is another matter entirely of course. Graham Sorry, realworld experience puts the lie to your statement. Hope you are *profoundly* offended, you America-hating ****tard. Lord Valve Expert |
#15
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Safe for 4 ohms into 8 ohms?
zyx wrote:
who to believe... who to believe... In the big picture of life, your likely do more damage to your hearing than the speakers. Without a matching load ( 4 == 4 , 8 == 8) the efficiency of the amp's output won't be met and your end up with less power output than what it is ideally capable of producing. I'm be more leery of the wattage of the speaker than the mismatch of Z but with a epi your ok. any links to learn more about it? By the way I already have an 12" 8 ohm speaker so I asked. Trust me ! .. This *is* the internet you know !This topic is discussed to death in most nwes groups. ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#16
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
zyx wrote
who to believe... who to believe... You will have the same problem wherever you go, I'm afraid. Sometime you will need to make a judgement. May as well be now. It should be obvious that this "eeyor" either can't read or has no grasp of simple logic, or both. Neither has he any real experience, and seems not to know the meaning of the word "unreliable". Greg's argument is clearly half-boiled. My logic is unassailable, and what you propose is a bit risky. Whether the risk is worth taking or not depends partly on the design of your amp, the quality of its components, and the state it is in, and partly on your propensity for taking risks. Lord Valve is a professional with many years of relevant experience. He seems to say the risk is not worth taking. Personally, if the amp is in good, clean condition and is well made to a sensible design, I wouldn't worry much about trying an 8 ohm speaker. I would expect the sound to be compromised though because of the shift in bandwidth and change in distortion content. Consider: everyone agrees that an open circuit is not a safe load for your amp. Everyone agrees that a 4 ohm speaker is a safe load. Somewhere in between a 4 ohm speaker and infinity, your amp will become seriously unreliable. *No-one here knows where that point is*. The consequence of you loosing the bet is potentially catastrophic. There is an outside chance of carnage in microseconds. The best speaker will be 4 ohms, without a doubt. Why mess about? Get a 4 ohm speaker. Why take a risk in the meantime, even if you judge it to be small? any links to learn more about it? By the way I already have an 12" 8 ohm speaker so I asked. Depends on what you already know, and how confident you are to apply it to new situations. Ohm's law should suggest that, for the same power output, a higher output impedance must lead to a higher voltage across it. This higher voltage will be reflected to the primary side of the transformer, leading to a higher maximum voltage at the valve anodes and transformer primary winding. An understanding of simple filters will explain why the bandwidth will shift. Some understanding of valve characteristics should explain why the distortion content will change. Nothing except experience will tell you whether this particular amp is likely to be OK with an 8 ohm speaker, or whether it's sound will be pleasing to you. That's why Lord Valve is your best bet. cheers, Ian |
#17
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Safe for 4 ohms into 8 ohms?
"zyx" wrote in message ...
"zyx" wrote in message ... I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms. Jam away? Such mixed results. who to believe... who to believe... Dude! Who to believe? Lord Valve is a musician who's been fixing guitar amps for longer than you've been on the planet, most likely. Graham is a blow hard know-it-all who responds to every question posted here even though his actual knowledge of tube equipment is exactly zero. I've been building and repairing tube equipment for 50 years, including guitar amps, home stereo & PA amps, and ham radio transmitters and receivers. Lord Valve is right. Doubling the load impedance on a tube guitar amp will cause much larger voltage swings in the primary of the output transformer (swings of thousands of volts!) which can cause arcs in the output tubes, tube sockets and tranny. Fred any links to learn more about it? By the way I already have an 12" 8 ohm speaker so I asked. |
#18
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Safe for 4 ohms into 8 ohms?
Phread wrote: "zyx" wrote in message "zyx" wrote in message I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms. Jam away? Such mixed results. who to believe... who to believe... Dude! Who to believe? Lord Valve is a musician who's been fixing guitar amps for longer than you've been on the planet, most likely. Graham is a blow hard know-it-all who responds to every question posted here even though his actual knowledge of tube equipment is exactly zero. Oh really ? I'm a pro-audio designer with 35 yrs experience in the business and have plenty of knowledge of tube circuitry and I even played a part in getting one tube guitar amp into volume production. I've been building and repairing tube equipment for 50 years, including guitar amps, home stereo & PA amps, and ham radio transmitters and receivers. Lord Valve is right. Doubling the load impedance on a tube guitar amp will cause much larger voltage swings in the primary of the output transformer (swings of thousands of volts!) which can cause arcs in the output tubes, tube sockets and tranny. Utter garbage. The voltage swings on the primary of the output transformer are typically well *under* a thousand volts. They cannot in any case exceed 2 x B+ in normal operation. How many transformers have you designed btw ? Graham p.s. to zyx, there are lots of amateurs here who reckon they know it all and dislike those with professional knowledge. They regularly make fundamental errors of fact and interpretation. There are only 2 professional designers here and they are Patrick Turmer and myself. Lord Valve is a very experienced tube expert at the practical level but has no design experience AFAIK. |
#19
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Safe for 4 ohms into 8 ohms?
Ian Iveson wrote: zyx wrote who to believe... who to believe... You will have the same problem wherever you go, I'm afraid. Sometime you will need to make a judgement. May as well be now. It should be obvious that this "eeyor" either can't read or has no grasp of simple logic, or both. Neither has he any real experience, and seems not to know the meaning of the word "unreliable". Greg's argument is clearly half-boiled. My logic is unassailable No, you're an utter cretin who can barely make a single post without some serious error. Graham |
#20
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Safe for 4 ohms into 8 ohms?
Despite what you may have seen from a loud-mouthed
know-it-all on this NG, don't worry. Loudspeaker impedances are only the roughest kind of estimate, good within a factor of ten, maybe. Operation without load is dangerous because it can cause (somewhat indirectly, but "cause") high voltage arcing, often in the output transformer's windings' insulation. Operation with any load even remotely like a speaker attached is safe. Never operate without a speaker attached, but don't worry about some bogus number. All good fortune, Chris Hornbeck "History consists of truths which in the end turn into lies, while myth consists of lies which finally turn into truths." - Jean Cocteau |
#21
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Safe for 4 ohms into 8 ohms?
Hi RATs and zyx!
Just get another 8 ohm speaker and wire them in parallel. This NG would rather trade insults than help you solve your problem. Yes, an 8 ohm resistor would work, sort of, but you can't hear the resistor's heat output Happy Ears! Al |
#22
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Safe for 4 ohms into 8 ohms?
In article ,
Eeyore wrote: Phread wrote: "zyx" wrote in message "zyx" wrote in message I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms. Jam away? Such mixed results. who to believe... who to believe... Dude! Who to believe? Lord Valve is a musician who's been fixing guitar amps for longer than you've been on the planet, most likely. Graham is a blow hard know-it-all who responds to every question posted here even though his actual knowledge of tube equipment is exactly zero. Oh really ? I'm a pro-audio designer with 35 yrs experience in the business and have plenty of knowledge of tube circuitry and I even played a part in getting one tube guitar amp into volume production. I've been building and repairing tube equipment for 50 years, including guitar amps, home stereo & PA amps, and ham radio transmitters and receivers. Lord Valve is right. Doubling the load impedance on a tube guitar amp will cause much larger voltage swings in the primary of the output transformer (swings of thousands of volts!) which can cause arcs in the output tubes, tube sockets and tranny. Utter garbage. The voltage swings on the primary of the output transformer are typically well *under* a thousand volts. They cannot in any case exceed 2 x B+ in normal operation. Oh really ? Are you sure about that 2 x B+ stuff? Have you ever considered that the transformer presents an inductive impedance to the tube(s) and if it is not sufficiently damped the anode voltage can easily exceed 2 x B+ when the tube is suddenly cut off? How many transformers have you designed btw ? to zyx, there are lots of amateurs here who reckon they know it all and dislike those with professional knowledge. They regularly make fundamental errors of fact and interpretation. There are only 2 professional designers here and they are Patrick Turmer and myself. What evidence do you have that there are only two "professional designers" here, there may be more than you suspect? Besides the fact that someone is a "professional designer" doesn't guarantee that they know what they are doing. Lord Valve is a very experienced tube expert at the practical level but has no design experience AFAIK. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#23
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Safe for 4 ohms into 8 ohms?
On Wed, 17 Jan 2007 17:53:35 +0000, Eeyore
wrote: Especially when a speaker's impedance can rise at some frequencies to easily TEN TIMES the 'nominal' figure. By your argument, driving the amplifier at such frequencies will destroy it. And furthermore a nominally stable (with nominal load) amplifier, with nominal levels of voltage feedback, which includes conventional guitar amplifiers, have very, very largely the same circuit voltages irrespective of load, over a wide range. The very real danger that has promulgated these myths is with an unstable amplifier, for example a legacy pentode- output guitar amplifier that oscillates when driven hard unloaded; not unknown for lots of classic designs. Oscillation, or even just overdrive, rapidly puts the output valves into class C; dI/dT makes multi-kiloJolt spikes across the output transformer when unloaded. Any remotely reasonable load keeps dI/dT to as safe a level as any other remotely reasonable load. Much thanks, as always, Chris Hornbeck "History consists of truths which in the end turn into lies, while myth consists of lies which finally turn into truths." - Jean Cocteau |
#24
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Safe for 4 ohms into 8 ohms?
"Eeysore the IDIOT " Utter garbage. The voltage swings on the primary of the output transformer are typically well *under* a thousand volts. They cannot in any case exceed 2 x B+ in normal operation. ** Really ????? Says an utter fool who has obviously NEVER tested * that * naive theory. Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV spikes on the output plates when operating into a speaker cab. LVs phrase " high tension flyback " is a very apt one - cos it don't happen with a resistive load. How many transformers have you designed btw ? ** More Red Herrings - anyone ?? ........ Phil |
#25
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Safe for 4 ohms into 8 ohms?
John Byrns wrote: Eeyore wrote: Phread wrote: Doubling the load impedance on a tube guitar amp will cause much larger voltage swings in the primary of the output transformer (swings of thousands of volts!) which can cause arcs in the output tubes, tube sockets and tranny. Utter garbage. The voltage swings on the primary of the output transformer are typically well *under* a thousand volts. They cannot in any case exceed 2 x B+ in normal operation. Oh really ? Are you sure about that 2 x B+ stuff? 100% Have you ever considered that the transformer presents an inductive impedance to the tube(s) and if it is not sufficiently damped the anode voltage can easily exceed 2 x B+ when the tube is suddenly cut off? The transformer will look like an inductor when there's no load. When there's a load on the secondary you will see a load on the primary. That's what transformers *DO* ! The load 'damps' the transformer's own inductance if you want to look at it like that. How many transformers have you designed btw ? to zyx, there are lots of amateurs here who reckon they know it all and dislike those with professional knowledge. They regularly make fundamental errors of fact and interpretation. There are only 2 professional designers here and they are Patrick Turmer and myself. What evidence do you have that there are only two "professional designers" here, Experience of the posters here. there may be more than you suspect? Not to my knowledge. Besides the fact that someone is a "professional designer" doesn't guarantee that they know what they are doing. Patrick and I do. Graham |
#26
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Safe for 4 ohms into 8 ohms?
Phil Allison wrote: "Eeysore the IDIOT " Utter garbage. The voltage swings on the primary of the output transformer are typically well *under* a thousand volts. They cannot in any case exceed 2 x B+ in normal operation. ** Really ????? Says an utter fool who has obviously NEVER tested * that * naive theory. Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV spikes on the output plates when operating into a speaker cab. In which case it's nothing to do with whether the load is a nominal 4 ohms or 8 ohms is it ? Note that I did say 'in normal operation'. If you grossly abuse an amplifier, all sorts of stuff can happen. Graham |
#27
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Stevenson = Charlatan
" Eeysore the LYING POMMY CHARLATAN " Utter garbage. The voltage swings on the primary of the output transformer are typically well *under* a thousand volts. They cannot in any case exceed 2 x B+ in normal operation. ** Really ????? Says an utter fool who has obviously NEVER tested * that * naive theory. Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV spikes on the output plates when operating into a speaker cab. LVs phrase " high tension flyback " is a very apt one - cos it don't happen with a resistive load. In which case it's nothing to do with whether the load is a nominal 4 ohms or 8 ohms is it ? ** WRONG ! The higher Z value, if mismatched at the output, will induce larger spikes. At some stage, insulation in the OT, the valves or sockets gives up, with a BANG. Note that I did say 'in normal operation'. ** Normal operation ( for a guitar amp) is the case. As I said - YOU have NEVER tested it. Cos YOU are a posturing, pig ignorant, ASD ****ed POMMY CHARLATAN !! ........ Phil |
#28
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Allison = Bear with sore head
Phil Allison wrote: As I said - YOU have NEVER tested it. So how about you tell us how you got it to do this then ? Graham |
#29
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Stevenson = Pommy Charlatan
"Eeysore the IDIOT " So how about you tell us how you got it to do this then ? ** Got what to do what - exactly ?? ....... Phil |
#30
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Allison = retarded kangaroo
Phil Allison wrote: "Eeysore the IDIOT " So how about you tell us how you got it to do this then ? ** Got what to do what - exactly ?? Get the amplifier to create 5kV on the OPT primary ! Graham |
#31
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Graham Stevenson = POMMY CRIM
"Eeysore the ****ING IDIOT " So how about you tell us how you got it to do this then ? ** Got what to do what - exactly ?? Get the amplifier to create 5kV on the OPT primary ! ** Already told you. ........ Phil |
#32
Posted to rec.audio.tubes
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Allison is a koala bear
Phil Allison wrote: "Eeysore the ****ING IDIOT " So how about you tell us how you got it to do this then ? ** Got what to do what - exactly ?? Get the amplifier to create 5kV on the OPT primary ! ** Already told you. You did NOT say how you did it. Graham |
#33
Posted to rec.audio.tubes
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Allison is a duckbilled platypus !
Phil Allison wrote: "Eeysore the ****ING IDIOT " ** Got what to do what - exactly ?? Get the amplifier to create 5kV on the OPT primary ! ** Already told you. You did NOT say how you did it. " Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV spikes on the output plates when operating into a speaker cab. LVs phrase " high tension flyback " is a very apt one - cos it don't happen with a resistive load. " " Normal operation ( for a guitar amp) is the case. " Ok - so *how easily* ? If you can't provide an answer you'll be seen to be simply posturing. Graham |
#34
Posted to rec.audio.tubes
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Allison's boomerang won't come back !
Phil Allison wrote: "Eeysore the LYING CHARLATAN " ** Got what to do what - exactly ?? Get the amplifier to create 5kV on the OPT primary ! ** Already told you. You did NOT say how you did it. " Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV spikes on the output plates when operating into a speaker cab. LVs phrase " high tension flyback " is a very apt one - cos it don't happen with a resistive load. " " Normal operation ( for a guitar amp) is the case. " Ok - so *how easily* ? ** The question has been answered. Do your own tests if you want proof. Do a GG search on " alt .guitar.amps" on the topic of "flyback spikes " for confirmation the phenomenon is well known. So you're just making it up ( you can't or refuse to explain it ). Just as I expected from a toaster repairman. Graham |
#35
Posted to rec.audio.tubes
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Stevenson = CRIMINAL SCUM
"Eeysore the Raving LUNATIC" " ** The question has been answered. Do your own tests if you want proof. Do a GG search on " alt .guitar.amps" on the topic of "flyback spikes " for confirmation the phenomenon is well known. So you're just making it up ( you can't or refuse to explain it ). ** What an UTTER non sequitur !!!!!!!! Someone one ought to shoot this pile of pommy **** right in the head. Then ask the Queen for a medal for services to the British Empire. ........ Phil |
#36
Posted to rec.audio.tubes
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Allison's boomerang came back
Phil Allison wrote: "Eeysore the Raving LUNATIC" " ** The question has been answered. Do your own tests if you want proof. Do a GG search on " alt .guitar.amps" on the topic of "flyback spikes " for confirmation the phenomenon is well known. So you're just making it up ( you can't or refuse to explain it ). ** What an UTTER non sequitur !!!!!!!! So go-on, what causes the 5kV ? You don't know do you ? Graham |
#37
Posted to rec.audio.tubes
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Allison's boomerang won't come back !
"Eeyore" wrote in
message Phil Allison wrote: "Eeysore the LYING CHARLATAN " ** Got what to do what - exactly ?? Get the amplifier to create 5kV on the OPT primary ! ** Already told you. You did NOT say how you did it. " Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV spikes on the output plates when operating into a speaker cab. LVs phrase " high tension flyback " is a very apt one - cos it don't happen with a resistive load. " " Normal operation ( for a guitar amp) is the case. " Ok - so *how easily* ? ** The question has been answered. Do your own tests if you want proof. Do a GG search on " alt .guitar.amps" on the topic of "flyback spikes " for confirmation the phenomenon is well known. So you're just making it up ( you can't or refuse to explain it ). Ironically, if one takes Phil's advice and searches alt.guitar.amps for posts about flyback spikes, you find him dodging the same basic question you asked about generating 5 Kv spikes around 2/25/2003, for example. Searching further, it looks like people are talking about loose 1/4 plugs, and the like. Based on what I know about generating inductive spikes, a wide range of inductances can suffice, and saying that 8 ohm speakers are always safe with a given amp would be a real stretch. |
#38
Posted to rec.audio.tubes
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Stevenson = CRIMINAL LIAR
"Eeysore the Raving CRIMINAL LUNATIC" " " Normal operation ( for a guitar amp) is the case. " Ok - so *how easily* ? ** The question has been answered. Do your own tests if you want proof. Do a GG search on " alt .guitar.amps" on the topic of "flyback spikes " for confirmation the phenomenon is well known. So you're just making it up ( you can't or refuse to explain it ). ** What an UTTER non sequitur !!!!!!!! So go-on, what causes the 5kV ? ** So you have no idea what the term " flyback spikes" refers to ? But you do now accept that they really exist in valve amps ??? Finally did a little Googling - did we ? ....... Phil |
#39
Posted to rec.audio.tubes
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Safe for 4 ohms into 8 ohms?
Chris Hornbeck wrote: Despite what you may have seen from a loud-mouthed know-it-all on this NG, don't worry. Well, ****-fire and boy howdy, son... You're wrong, but you can derive some small solace from the fact that you're wrong for all the right reasons, chief among them being ignorance regarding actual field operating conditions for *guitar* amplifiers. You've also never seen an Epiphone Valve Junior, nor the schematic thereto. Right? So - this amp runs a single EL84, giving an output of around 4 watts RMS. One 12AX7. SS bridge rectifier for the HV, as well as one for the heaters. No screen resistor. The entire shebang - including the speaker - *retails* for $139, and can often be had for less than $100, brand new in the box. In short, it's a cheap-ass piece of Chinese ****, a bare-bones minimum design intended to sell for the lowest price possible - less, in fact, than most audiophools spend on a couple of snob-glass preamp tubes. Think any corners were cut? I've had around a half-dozen of these across my bench in the last year. All but one had the same problem: fried socket. Cause: "I hooked it up to my (brand XYZ) speaker cabinet cuz it wasn't loud enough for me to play with a drummer." Said speaker cabinet, of course, was nearly always an 8-ohm box. One was 16. This is a 4-watt amp commonly purchased by the worst gear abusers on the planet: guitar pickers. Since it's only 4 watts, it is *always* played at full-bore output clipping, for max distortion and "blues tone." Its (often short) life is one of maximum stress, placed upon the sleaziest components imaginable. Now, son - you may know what you may know, and it may well be at odds with what I've said, but I have hands-on time with this particular gizmo, and I know for certain it eats tube sockets when operated into a higher than spec load. If you want to show me the math which proves that a bumblebee can't fly, be my guest. I've seen 'em fly, so I'll take your "knowledge" with a grain of salt, if that's OK with you. You don't catch my ass on this NG telling the audiophools about their SET 300B snob designs for a fairly good reason: I know jack **** about 'em. The difference between me and the audio******s is that I can admit it. Lord Valve Expert Guitar Amp Dude |
#40
Posted to rec.audio.tubes
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Allison's an Antipodean obfuscator.
Phil Allison wrote: "Eeysore the Raving CRIMINAL LUNATIC" " " Normal operation ( for a guitar amp) is the case. " Ok - so *how easily* ? ** The question has been answered. Do your own tests if you want proof. Do a GG search on " alt .guitar.amps" on the topic of "flyback spikes " for confirmation the phenomenon is well known. So you're just making it up ( you can't or refuse to explain it ). ** What an UTTER non sequitur !!!!!!!! So go-on, what causes the 5kV ? ** So you have no idea what the term " flyback spikes" refers to ? I know exactly. But you do now accept that they really exist in valve amps ??? If the load's disconnected for sure. Finally did a little Googling - did we ? No need. Now, how did *YOU* get 5kV flyback spikes. What was the load ? How hard was the amp being driven ? What was the input signal ? Graham |
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