Klipsch Forte IV ... what amp ?
No , I am not asking for a particular amp style and brand here . Although I am not refusing any suggestions either !
What I would like to know first is what characteristics to look for in an amp to drive these speakers (Forte 4’s) to full performance .
Such characteristics as :
1.) What is needed to handle the low impedance of 4 ohms ?
2.) While the sensitivity is listed at 99 dbs. it is considered to be closer to @ 96 dbs,
3.) What about negative feedback ?
4.) Will the 12" woofer and 15 " rear radiator need special attention also ?
5.) Do the horns require special consideration ?
I feel that these considerations will go further to getting it right than , " hey , just get a tube amp and enjoy " .
Thank you & Be Safe .
Learning to bias an amp (at least in this case) is VERY easy. You just need a cheap multi meter and a small screw driver. I'm no electrical genius by a long shot but if you can turn on a multimeter you can bias this tube amp. |
Interesting thought. I am running Penta KT88's with the CH LP66S amp I have two preamps, a Don Sachs DS2 and a CJ 17LS2. When I run the DS2, I get a horn treble at high volumes that is hard on the hearing; but the ultimate amount of aliveness is there. When I run the CJ 17LS2, I tame that treble edge at high volume but lose the last bit of liveness. Not sure what I need to do. The Forte's provide some great dynamics, slam, and soundstage at higher volumes; the treble edge is killing me. Wondering if some Quicksilver monos is the answer or maybe Pass/Fest Watt.. Thanks for listening, Dsper |
Actually the Mid Monos don't even need a meter . To bias you just turn each tubes bias pot fully counter clockwise . Old Mid Monos have one potentiometer per amp to bias and for those matched tube pairs for each amp are recommended. The newest version has a bias pot for each tube which is better. So with all pots counter-clockwise, turn the amps on and let warm up for a few minutes I recommend doing one amp at a time. After it has been on for a few minutes, press the bias test button, there are two for new units. Press and hold the button as you slowly turn the pot clockwise.....slowly. the LED will start to glow. Just when it starts to glow, back off a little until it goes out. Let the amp warm up for 15 , checking the single or both LEDs if so equipped to make sure it doesnt glow bright RED. If it does back off counter clockwise a little. After the amp has been on for at least 15 or 20 min check bias and adj clockwise until the LED just starts to glow red. REMEMBER TO PRESS THE LED CHECK BUTTON AND HOLD WHILE ADJUSTING..... The goal is not to bias them hot for a long life. If the LED barely glows the amp is in the correct range. |
