Radio Shack has 8 ohm 20 watt resistors for $1.99 each that should work fine as long as you don't crank it up too loud. Just disconnect the speakers and put one between the binding posts where the speaker cables were. I don't know how much power your amp puts out but you don't want to run it wide open anyway. You have to feed it a signal to get maximum benefit, so a CD player on repeat or from your tuner if you have one. Turn it up to where a moderate volume level would be through the speakers and this should be less than 20 watts. Feel the resistors after a few minutes and unless they are too hot to touch for more than a few seconds you should be fine. |
Purchase a quantity of 14 of a part number 004-30 from Parts Express. You will end up using 7 per channel, all wired in parallel. This means that all seven resistors will have all their leads tied together on one side and tied together on the other. In effect, the signal comes into one common point on side A ( we'll call this positive ), can choose a path through any of the resistors, and then exits on side B ( negative ). In effect, the signal is passing through the resistors like it would a speaker. You can connect the resistors aka "dummy load" to the amp using some old zip cord speaker cable or whatever you have laying around. If you like, you can use your existing speaker cables if you can find a way to connect the resistors to them in a secure manner. Using this specific approach will provide you with 70 watts of power handling and a nominal impedance of appr 4.2 ohms. Power handling should be sufficient since the average power of most music is but a few watts. The lower impedance will pull more current out of the amps. More current is equivalent to more signal flow and thermal stress, causing the amp to break-in both faster and more thoroughly. When you set this up, pick out a disc that has a high average signal ( loud ) and is extended in both bass and treble response. Adjust the volume control up to a point that you would normally find yourself listening to when running your speakers and make note of this position. Shut the system down, remove your speakers from the system and connect the dummy loads. If you can find some way to elevate the dummy loads i.e. allows air-flow around all sides of the resistors, you'll be better off. Adjust the volume up to this point again and have at it. After playing a few selections, feel the resistors to see if they are warm. If you feel noticeable warmth coming from them, turn the volume down a bit. What you are looking for is to pump as much signal through the amp and dummy load without thermally stressing either of them. Just remember that if you can feel noticeable warmth from the dummy loads after a song or two, continual play will only get them hotter / have more potential for damage. As such, find a convenient spot on the volume that is both high enough to let the amp do its' thing without burning up the resistors. Hope this helps and i've you've got more questions, fire away. Sean > |
Looks like Herman and i were posting at the same time. We are both on the same page, i just went the "over-kill" route : ) You can achieve much the same effect that i mentioned above by doubling up two of the resistors per channel that Herman linked to. This would give you a 4 ohm load with 40 watts of power handling, which should be plenty. Not only is this a LOT cheaper, i'm sure that you're closer to a Radio Shack than you are to Parts Express. Convenience and timing count, so Herman scores more points on this one than i do : ) Sean > |
Thanks Herman and Sean. I will stop by Rat Shack and pick up 4 as suggested. I have some banana speaker plugs like these: http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=091-1260&DID=7. Do I just pair up the resistors and clamp the leads into the banana plugs then plug them in? Sounds easy enough. Would it be any safer using 3 of these resistors per channel? Rick |
yes, all you have to do is connect them as you mentioned. That is, so long as the leads are long enough to allow bending to reach the amps' binding posts. Using three of them in parallel will produce an appr 2.2 ohm load, which is kind of low right off the bat. On top of that, you would now be pulling quite a bit more current, causing both the amp and resistors to heat up. Stick with two of them in parallel and see how that works. Other than that, i wonder how richly these amps are biased? I know that Klaus is not much for spec's, but i'm curious as to where these amps switch from Class A over to Class B??? Sean > |
Jayctoy, Thanks for your encouragement. I know it is going to take some time to break these in. ....Patience....Problem for me is I only get a few hours a week to play my system. At that rate, it will take months to pile up any time on the amps. I am not able to leave the system running through the speakers when I'm not home (WAF). So if I can run the system quietly, I can run it 24/7 and get the first 300 hours or so out of the way quickly. I was home all last week and managed to play them quite a bit, so I'm up to about 70 hours on the amps. They are getting a bit more dynamic. There is a muddy distorted image in a small area of the middle frequencies, most noticable playing acoustic guitar tracks. I really want that part to go away. Patience....Patience... All of the break-in issues aside, I can tell these amps are going to be special. I can hear flashes of brilliance in them. |
I have built the dummy load using the 20 watt 8 ohm Radio Shack resistors, 2 per channel. I mounted them on some screw down terminals and ran about 3' feet of speaker wire off of them. I managed to mount the terminals on wood blocks so there would be some airflow around the resistors. They have been running for about 2 hours with no noticable build up of heat. So I'll run these babies 24/7 and see if this speeds up the break in process at all. Thanks again for all of you help! Rick |
