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Bi amp and bias issue

Hello I need help with biamping my magnepan 3.5r I have a krell Kav 2250 25.7 gain 2.53vrms input sensitivity for bass and rogue audio m150 29gain 1vrms input sensitivity.

I tried using stock crossover using krell for bass and rogue for mid and tweeter and it works but only when i use triode mode on rogue if i switch to ultra linear when I try to bias the meter on rogue oscillates. 
I contacted rogue they said its the tweeter load the amp is not designed to play just the tweeters but i tried running just the tweeter with it and not turn on the krell and it does not oscillate . 
I replaced the 12ax7 driver tubes on the rogue with 12au7 and that stopped the oscillation but rogue said they dont know how it will affect the amp in long term. 
Another problem im having is that the rogue plays alot louder than the krell

also if anyone is curious the rogues sound better playing the speakers than the krell rogues are 150 watts into 4ohm and krell are 500w the bass sounds better with most music including pop techno hip hop with the rogues the krell sounds better when theres alot of energy lots of fast bass sounds where the rogues dont have as much grip during those passages.

the rest of the system is denon dl103r mc /jensen mc transformer/rega p3 /hagerman trumpet phono/
128x128beep23
georgehifi's avatar
georgehifi
10,312 posts
 


I don’t agree George, keep all resistances to a minimum.


That’s your prerogative,

Yes (min resistance) that is normally the way for full range, and when the bass is involved, for better damping factor.
But because it’s just the mids and treble, it won’t make any difference, and will be beneficial to the stability of the amp.
As the amp will be a little less stable in UL mode compared to Triode, and goes into semi oscillation when it sees that inductor across it’s output and certain frequencies. And the 50w 1ohm series resistor should cure that without any side effects.
beep23 Planers and ESL’s are known for their naturalness through the mids and highs, don’t "sterilize" them up with using active electronic xovers, keep the passive to feed them.

Cheers George
fiesta75
1,378 posts
 
Yes I know it is. Your opinion George, everyone is entitled to theirs. If your amps can't handle the current, change amps. Add a resistor if needed, but adding resistance will be detrimental to the high frequency response. I like accuracy, that's why I use solid silver wire or silver plated copper wire for most applications when I can afford it.
invalid
1,190 posts
 
You can use a passive line level crossover with attenuators with some speakers, not sure about the magnepans.
georgehifi's avatar
georgehifi
10,312 posts
 
Add a resistor if needed, but adding resistance will be detrimental to the high frequency response. I like accuracy

Sorry, no it won't.Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 

Here is why, for the 1ohm resistor to create even the slightest HF filter in the highs on these Maggies. The Maggie’s panel themselves would have to have a parallel capacitance from pos to ground as seen by the 1ohm resistor of 10uF or higher which no amp could handle.

Like I said beep23, just use the $6.00 50watt 1ohm resistor to make the Rogue stable when in UL mode.
https://www.newark.com/vishay/rh0501r000fe02/wirewound-resistor-1-ohm-50w-1/dp/41K9144

https://ibb.co/HT8w2jz

Cheers George
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