lewiswhitebass Posted July 19, 2022 Author Share Posted July 19, 2022 18 minutes ago, Downunderwonder said: I am seeing a problem here if the 8 ohm cab was (actually) a 4 ohm 410HLF. A pair of 4 ohm cabs is a 2 ohm load. That's nasty. The 410 HLF was used standalone so that wasn't the problem Quote Link to comment Share on other sites More sharing options...
Downunderwonder Posted July 19, 2022 Share Posted July 19, 2022 36 minutes ago, lewiswhitebass said: The 410 HLF was used standalone so that wasn't the problem Agedhorse raised concern that prior out of spec loading had caused damage already. Going hard out into 4 ohm being just the last straw. Given that you had the impedance wrong on the HLF it's not a stretch to having it wrong and hooking up 2 ohms previously. Quote Link to comment Share on other sites More sharing options...
stevie Posted July 20, 2022 Share Posted July 20, 2022 How does protection work on an amp like this? I've always assumed that they all have some kind of protection against sub-optimal loads or short circuits. Am I wrong? Quote Link to comment Share on other sites More sharing options...
agedhorse Posted July 20, 2022 Share Posted July 20, 2022 14 hours ago, stevie said: How does protection work on an amp like this? I've always assumed that they all have some kind of protection against sub-optimal loads or short circuits. Am I wrong? Most do have protection circuits, but it's important to recognize that protection circuits are not 100% effective against all faults and all fault conditions. Different designers and different companies place different amounts of importance on protection circuits since they add to the cost of the design while being almost impossible to market as a valuable feature to the majority of customers. 1 1 Quote Link to comment Share on other sites More sharing options...
Downunderwonder Posted July 20, 2022 Share Posted July 20, 2022 58 minutes ago, agedhorse said: market as a valuable feature to the majority of customers I think most of the value would kick in as saved staff time pissing around on invalid warranty claims caused by user error. That would filter back to a slightly keener price. Quote Link to comment Share on other sites More sharing options...
agedhorse Posted July 21, 2022 Share Posted July 21, 2022 2 hours ago, Downunderwonder said: I think most of the value would kick in as saved staff time pissing around on invalid warranty claims caused by user error. That would filter back to a slightly keener price. Unfortunately, there’s little marketing value, but it does save massive costs to both the manufacturer and the player. Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted July 21, 2022 Share Posted July 21, 2022 10 hours ago, agedhorse said: Most do have protection circuits, but it's important to recognize that protection circuits are not 100% effective against all faults and all fault conditions. Different designers and different companies place different amounts of importance on protection circuits since they add to the cost of the design while being almost impossible to market as a valuable feature to the majority of customers. One of the reasons I would avoid 2 ohm operation. Its too close to a short for my liking. I also agree about protection, its like contraception. Not 100% effective. My dad got an apology from the condom manufacturer when I was born 3 Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted July 21, 2022 Share Posted July 21, 2022 Are you sure you weren't a grudge baby? Someone had it in for your dad. 🤪 1 Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted July 21, 2022 Share Posted July 21, 2022 4 minutes ago, BassmanPaul said: Are you sure you weren't a grudge baby? Someone had it in for your dad. 🤪 The old ones are the best😀 1 Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted July 21, 2022 Share Posted July 21, 2022 On 20/07/2022 at 09:08, stevie said: How does protection work on an amp like this? I've always assumed that they all have some kind of protection against sub-optimal loads or short circuits. Am I wrong? No you are right, at least over voltage and over current protection. Some have under voltage protection too. over current will protect against shorts or sub optimal loads. One of the problems with some speakers is that they go under their quoted impedance at certain frequencies, so over current protection is vital. 1 Quote Link to comment Share on other sites More sharing options...
agedhorse Posted July 21, 2022 Share Posted July 21, 2022 11 hours ago, Chienmortbb said: One of the reasons I would avoid 2 ohm operation. Its too close to a short for my liking. I also agree about protection, its like contraception. Not 100% effective. My dad got an apology from the condom manufacturer when I was born There is no problem designing for 2 ohm operation with identical reliability to an amp with 4 ohm minimum load operation. In amps I have designed, the reliability statistics fully support this. 1 hour ago, Chienmortbb said: No you are right, at least over voltage and over current protection. Some have under voltage protection too. over current will protect against shorts or sub optimal loads. One of the problems with some speakers is that they go under their quoted impedance at certain frequencies, so over current protection is vital. There are many different protection schemes depending on the type and class of amp. These protection schemes include: - AC line over-voltage protection - AC line under-voltage protection - power amp thermal protection - power supply thermal protection -output stage over-current protection - output stage leading phase angle protection (illegal capacitve load) - DC offset protection - power supply over-current protection - excessive HF content protection - short cycle inrush current protection Some amps have many of these protections, some have just a few. There is substantial cost (and design effort) to these but when you can reduce the failure rates to almost zero by including them, in general it's a good choice. 3 Quote Link to comment Share on other sites More sharing options...
Crawford13 Posted August 3, 2022 Share Posted August 3, 2022 Did you get a solution from PMT? Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted August 3, 2022 Share Posted August 3, 2022 On 21/07/2022 at 21:32, agedhorse said: There is no problem designing for 2 ohm operation with identical reliability to an amp with 4 ohm minimum load operation. In amps I have designed, the reliability statistics fully support this. I am sure you are correct but it is my personal preference. Quote Link to comment Share on other sites More sharing options...
lewiswhitebass Posted August 19, 2022 Author Share Posted August 19, 2022 On 03/08/2022 at 08:38, Crawford13 said: Did you get a solution from PMT? In the end yes! They let me put the value of the amp towards my new Kemper 2 Quote Link to comment Share on other sites More sharing options...
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