MikeSt Posted April 17, 2009 Share Posted April 17, 2009 I guess it's because of an impedance mismatch because I have 6ohm KG4's but this is the second amp I've blown. The first was a Marantz 2215 and now it's the HK730. I don't listen to it extrememly loud but there is a lot of bass in the movies. Or maybe it's because the speakers are rated at 100watts and the amps were 15 and 25 watts. Quote Link to comment Share on other sites More sharing options...
tigerwoodKhorns Posted April 17, 2009 Share Posted April 17, 2009 Noting that you have mentioned matters. Check the fuses... Quote Link to comment Share on other sites More sharing options...
SilverSport Posted April 17, 2009 Share Posted April 17, 2009 I had no problems listening to music with "6 ohm" kg2s and "8 ohm" Heresys...the speakers can handle up to 100 watts...they don't mind if you use less wattage...older recievers/amps???...methinks they were on their way out anyway??? Bill Quote Link to comment Share on other sites More sharing options...
Guest " " Posted April 17, 2009 Share Posted April 17, 2009 I blew an amp once. I had 2 sets of speakers connected. Each speaker system claimed 8 ohms. The reciever claimed 4, 6, or 8 ohms were possible. It turned out the speakers dipped below 4 ohms, while still being an average of 8 ohms. End result, using 2 pairs as claimed that was possible in the manual resulted in a dip below 2 ohms. The 2 ohm dip blew the amp. Quote Link to comment Share on other sites More sharing options...
MikeSt Posted April 17, 2009 Author Share Posted April 17, 2009 I didn't mention I had my turntable on top of it. That might have gotten it hot. It couldn't be a fuse because I'm still getting sound from the blown channel, it's just really low. Quote Link to comment Share on other sites More sharing options...
skonopa Posted April 17, 2009 Share Posted April 17, 2009 I didn't mention I had my turntable on top of it. That might have gotten it hot. It couldn't be a fuse because I'm still getting sound from the blown channel, it's just really low. Could be, but not entirely sure. I don't think it helped any. I tend to like to give my amps plenty of "breathing room", espeically that B&K (talk about a friggan space heater!). I would also go and check your speaker wire connections and make sure you don't have stray end/loose wire that may be crossing with the other channel's connection or touching a metal part on the chassis/frames. I had my amp shut down into "protection mode" once and it tuned out it was a fray that was touching the metal backplate, causing a short (since corrected by using banana plugs). Quote Link to comment Share on other sites More sharing options...
MikeSt Posted April 17, 2009 Author Share Posted April 17, 2009 I had my amp shut down into "protection mode" once and it tuned out it was a fray that was touching the metal backplate, causing a short (since corrected by using banana plugs). I checked the speaker wire is fine. Someone else mentioned 'protection mode' because I noticed when I turn the amp up real loud the volume gets real low, then when I turn the volume knob down it goes back up again. Quote Link to comment Share on other sites More sharing options...
russ69 Posted April 17, 2009 Share Posted April 17, 2009 These are old low powered receivers, not the most robust pieces when they were new. You might think about something with some power for the next unit. I would check the internal and external fuses first, just to be sure. Thanx, Russ Quote Link to comment Share on other sites More sharing options...
MikeSt Posted April 17, 2009 Author Share Posted April 17, 2009 You might think about something with some power for the next unit. I would check the internal and external fuses first, just to be sure. Can you tell me what to look for? I assumed a fuse is either open or closed. I didn't know it could still play with a blown fuse. Quote Link to comment Share on other sites More sharing options...
Marvel Posted April 17, 2009 Share Posted April 17, 2009 These are old low powered receivers, not the most robust pieces when they were new. The H/K 730 is a very conservative 40wpc, and has always been quite robust. People don't continue to buy them just because they are now inexpensive.The H/K 730 tech manual is attached. A fuse is either blown or not. A multimeter will tell you, but you have to remove the fuse to check. HK730_sm.pdf Quote Link to comment Share on other sites More sharing options...
russ69 Posted April 17, 2009 Share Posted April 17, 2009 Fuses are tricky little devils, you can't always tell if they are blown. I just put in fresh good ones. I haven't blown a fuse in 30 years, I lost the desire to damage loudspeakers and my hearing years ago. Thanx, Russ Sorry Marvel, but those are/were near bottom of the line receivers in their day. H/K and Marantz were past their prime by then, power was king and the little ones were made on the cheap. I know a lot of people on this board love these things but they are not for me. There is little from the 70's mass consumer electronics that I find listenable. Quote Link to comment Share on other sites More sharing options...
MikeSt Posted April 24, 2009 Author Share Posted April 24, 2009 The H/K 730 tech manual is attached. A fuse is either blown or not. A multimeter will tell you, but you have to remove the fuse to check. Thanks for the manual. As it turns out it's the KG4 that's blown. I assumed it was the amp since the exact same sound was coming out of my marantz before the left channel blew in that one. Also, it seemed to be going into protection mode, so I just assumed.. now I've got to get some more speakers. Someone local is selling some early 80's Heresy's. Quote Link to comment Share on other sites More sharing options...
djk Posted April 24, 2009 Share Posted April 24, 2009 "but those are/were near bottom of the line receivers in their day. H/K and Marantz were past their prime by then, power was king and the little ones were made on the cheap." The 730 was top-of-the-line in the mid 70s. They had big transformers, big heatsinks , and big steel TO-3 outputs. Everything eventually wears our, even the graite steps at our local Carnegie library Quote Link to comment Share on other sites More sharing options...
russ69 Posted April 24, 2009 Share Posted April 24, 2009 djk, What was the model line up during the 730 model time frame? They were not on my radar, even though I had a Citation 12 at the time. Thanx, Russ Quote Link to comment Share on other sites More sharing options...
djk Posted April 25, 2009 Share Posted April 25, 2009 There were only three, 330C, 430, and 730. Earlier on there was a 230, but it was a complete POS. I bought my father a 730 and it has never needed repair. One coupling cap has some DC leakage and makes the volume control noisey for a few minutes when you first turn it on. "I had a Citation 12 at the time." We sold more Citation 16s than 12s, not sure why. In a points contest, two of the salemen aquired enough points selling the receivers to win Citation 16s. Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted April 25, 2009 Share Posted April 25, 2009 It sucks when amps clip Quote Link to comment Share on other sites More sharing options...
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