Passive bi-amp question
This Schiit SYS will let you match the levels of the two amps that you are going to use! https://www.schiit.com/products/sys |
romney80 OP Yogiboy is correct, just use a $49 Schiit Sys https://www.schiit.com/products/sys on the louder amp if both amps are not the same gain, so you can make them the same with it. Then drive the lot with your main preamp. Here is how to wire it up https://ibb.co/x6dKF0N Cheers George |
Ok. The gain of my current amp is 29 db, input sensitivity is 1.4 volts RMS, impedance is 7.5 kohm, damping factor (at 8 ohm) >1000, power output 250 watts at 8 ohms. I am considering Luxman M-900u, which also has gain of 29 db, input sensitivity of 1.24V/150W (8ohm), input impedance of 34 kohms (balanced), damping factor of 710, power output 150 watts at 8 ohms. The gain seems to be matched and input sensitivity seems to be close (even though different watts power at 8 ohms). Will this be acceptable for biamp with my current amp ?. |
romney80 OP Yes close, you may not need the Sys, but get it anyway as it comes with a trial period, so you can send it back, it is only $49 If it’s on the bass amp, then you "can" raise it slightly for those "bass shy albums", or lower it slightly if it’s on the treble amp. And yes I’m also against active bi-amping as it sterilizes the mids and highs, it’s ok on the bass though and use the speakers passive xover on the mids and highs. Cheers George |
The thing to keep in mind, with amps, is that the gain specification measurement is just not that important to makers. That is, maybe they will specify 29 dB but maybe it’s 28.5 and maybe it’s 29.7. It's rarely 29.00 dB Since 99.9999 of their customers will use 1 stereo amp, accuracy here is just not that important. I’m sure it is consistent among the same model but across different models or makers probably not. So, good to have some way of measuring the relative gain and adjusting if wrong. |
A few decibels is actually a LOT! The difference between 29 db and 32 db means that you would have either too much bass or very weak bass depending on what amp you put on the bottom. If Erik is correct that gain is not always 100% perfect specification, then the variance might be small. A .7 decibel variance is not that much, but I wouldn't say it's that bad. Speakers are never perfect anyway and actually will vary up to 3-5 decibels through the entire frequency range. If you put a amp on the woofer that is .7 db higher gain, you might have a "slightly thicker" bass midbass. It's almost like a very slight EQ. I would ignore those "1.24V" sensitivity numbers. It is just a representation of how much input volts are required to have the amp output a certain amount. The "gain" is the only thing you need to look at. |
Sounds good. Thanks for those technical inputs. I am assuming, even if the companies mention 29 db gain, they may vary at best few decimal of decibels. I am OK with that. Just one question though. It may be silly. Does it matter even if the amp have different watts of power (like 250 vs 150 at 8 ohms) even if gain is same. |
