isthatfreedomrock Posted March 9 Share Posted March 9 (edited) I am currently using a Kenwood KA5700 Integrated Amplifier to power all 4 of my speakers (a pair of KG4's and Forte II's). Has worked fine for a few years but the bulb just went out. So might replace the unit all-together. Question 1: Is that amp sufficient or is it under-powering my speakers? Question 2: Is there a modern amp anyone can recommend that is strong enough to power all 4 speakers? Thanks! Edited March 9 by isthatfreedomrock Quote Link to comment Share on other sites More sharing options...
Peter P. Posted March 9 Share Posted March 9 What does "the bulb just went out" mean? The amp is rated for 40W/ch into 8 ohms. What's the resistance rating for your kg4's and your Forte 1's? It should be on the back of the speaker. Since you've been operating your speakers for many years without an issue, I'd conclude it's not the amp being underpowered or the output impedance going too low, all channels driven. It could merely be a component failure due to the age of your amp, which was manufactured in the late 70s. Repair might be the affordable solution assuming parts are available. You could take the cover off and see if there is an internal fuse. If so, replace the fuse and see what happens. 1 Quote Link to comment Share on other sites More sharing options...
isthatfreedomrock Posted March 9 Author Share Posted March 9 9 minutes ago, Peter P. said: By "the bulb went out" I mean that it simply stopped lighting up today. And the needles aren't moving at all either. The unit still powers up and, plays fine as I tested it. It's powering as normal through the speakers. Yes i've seen the bulb is replaceable and even fuses, but I'm not sure of what I will get myself into. I was mostly wondering if i can use a stronger amp to push the speakers or if i was using an appropriate power source. I'm not eduacated enough with ohms, watts to make a good decision. LOL. - Just need some opinions. 9 minutes ago, Peter P. said: What does "the bulb just went out" mean? The amp is rated for 40W/ch into 8 ohms. What's the resistance rating for your kg4's and your Forte 1's? It should be on the back of the speaker. Since you've been operating your speakers for many years without an issue, I'd conclude it's not the amp being underpowered or the output impedance going too low, all channels driven. It could merely be a component failure due to the age of your amp, which was manufactured in the late 70s. Repair might be the affordable solution assuming parts are available. You could take the cover off and see if there is an internal fuse. If so, replace the fuse and see what happens. IMG_0947.HEIC IMG_0949.HEIC IMG_0948.HEIC Quote Link to comment Share on other sites More sharing options...
YK Thom Posted March 10 Share Posted March 10 Both of your speakers are very efficient and are 8 and 6 ohms. I can't see it as under powered. I found the spec sheets for each of them, although you may already have them. I agree with Peter P, this is a failure within your vintage receiver. With any luck a minor issue, perhaps fuse. If not you may have take it in for servicing and /or purchase a new unit. There are so many good ones on the market available opening up a whole new rabbit hole. A nice unit like this would be worth having repaired IMO. forte-brochure.pdf KG-4-Spec-Sheet.pdf 1 Quote Link to comment Share on other sites More sharing options...
isthatfreedomrock Posted March 10 Author Share Posted March 10 1 hour ago, YK Thom said: Both of your speakers are very efficient and are 8 and 6 ohms. I can't see it as under powered. I found the spec sheets for each of them, although you may already have them. I agree with Peter P, this is a failure within your vintage receiver. With any luck a minor issue, perhaps fuse. If not you may have take it in for servicing and /or purchase a new unit. There are so many good ones on the market available opening up a whole new rabbit hole. A nice unit like this would be worth having repaired IMO. forte-brochure.pdf 630.23 kB · 0 downloads KG-4-Spec-Sheet.pdf 321.72 kB · 0 downloads awesome. thank you for your input and the spec sheets. I'll do some research and look into getting it repaired. 1 Quote Link to comment Share on other sites More sharing options...
Scott Grammer Posted March 10 Share Posted March 10 Hi. I work on vintage audio gear for a living, so I thought I'd try to give you a little more solid answers to your questions. As for the bulb going out, most likely it just burned out. There is a fuse for that lamp, however, but I doubt you'll find it blown. It's marked "Fm3" on the circuit board. You'll find three fuses on the main circuit board, two parallel to each other and one at a right angle to them. That one at a right angle is the fuse you're interested in. It's a 500mA (or 1/2 amp) fast-blow fuse. As for the meters not working, there's nothing in common between the lamp and the meters, and the meters are literally powered by the signal going to your speakers, so I'm at a loss as to why they would not work if the amp is playing. There are a pair of 47 microfarad capacitors in the meter circuits that, if they have become leaky enough, could cause the meters to stop working, but it seems unlikely. It may just be that you don't use enough amplifier power at your normal listening levels to make the meters swing. And that amp should be more than powerful enough for such sensitive speakers, unless you have a really large listening room and like to listen really, really loud. Still, if the amp has never been serviced, now would be a good time to take it to someone experienced with vintage audio gear and let them give it a check-up. And if you decide to check on that fuse, PLEASE unplug the unit from the AC power first. Scott. 4 Quote Link to comment Share on other sites More sharing options...
isthatfreedomrock Posted March 11 Author Share Posted March 11 On 3/9/2024 at 11:28 PM, Scott Grammer said: Hi. I work on vintage audio gear for a living, so I thought I'd try to give you a little more solid answers to your questions. As for the bulb going out, most likely it just burned out. There is a fuse for that lamp, however, but I doubt you'll find it blown. It's marked "Fm3" on the circuit board. You'll find three fuses on the main circuit board, two parallel to each other and one at a right angle to them. That one at a right angle is the fuse you're interested in. It's a 500mA (or 1/2 amp) fast-blow fuse. As for the meters not working, there's nothing in common between the lamp and the meters, and the meters are literally powered by the signal going to your speakers, so I'm at a loss as to why they would not work if the amp is playing. There are a pair of 47 microfarad capacitors in the meter circuits that, if they have become leaky enough, could cause the meters to stop working, but it seems unlikely. It may just be that you don't use enough amplifier power at your normal listening levels to make the meters swing. And that amp should be more than powerful enough for such sensitive speakers, unless you have a really large listening room and like to listen really, really loud. Still, if the amp has never been serviced, now would be a good time to take it to someone experienced with vintage audio gear and let them give it a check-up. And if you decide to check on that fuse, PLEASE unplug the unit from the AC power first. Scott. @Scott Grammer thank you, Scott. very detailed and helpful information. I appreciate it! 2 Quote Link to comment Share on other sites More sharing options...
JohnA Posted March 21 Share Posted March 21 On 3/9/2024 at 5:04 PM, isthatfreedomrock said: I am currently using a Kenwood KA5700 Integrated Amplifier to power all 4 of my speakers (a pair of KG4's and Forte II's). Has worked fine for a few years but the bulb just went out. So might replace the unit all-together. Question 1: Is that amp sufficient or is it under-powering my speakers? Question 2: Is there a modern amp anyone can recommend that is strong enough to power all 4 speakers? Thanks! There is no such thing as "underpowering" speakers. Once the sound quality and distortion of the amp is good enough, it is only a matter of, "Is it loud enough?" If you can achieve the loudness of the live music you like (say 105 dB for an orchestra), you're good. 1 Quote Link to comment Share on other sites More sharing options...
82 Cornwalls Posted March 21 Share Posted March 21 39 minutes ago, JohnA said: There is no such thing as "underpowering" speakers. If you can achieve the loudness of the live music you like (say 105 dB for an orchestra), you're good. If you can achieve the loudest levels YOU listen at in YOUR home you are good. 1 Quote Link to comment Share on other sites More sharing options...
Mikekid Posted March 21 Share Posted March 21 Lately, we've been running a 2.3 watt per channel tube amp through our ChorusII's . Amazingly beautiful sound and LOUD as we would ever need! 101 db @ 1 watt/1 meter though. Looks like Scott has you covered on fixing the Kenwood 👌 Good luck~ Mike Quote Link to comment Share on other sites More sharing options...
Last Lemming Posted March 23 Share Posted March 23 In my experience the fortes get better with more clean wattage. I don’t know anything about your current amp but I have an amp with 100w into 8 ohm and it sounds waaaay better than my Decware 6w integrated. Quote Link to comment Share on other sites More sharing options...
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