Biamping with tubes and SS: Input sensitivity key?


When biamping a low sensitivity speaker (85db), 4 0hm impedance, with a 800 Hz crossover with a TAD-60 (input sensitivity given as 1 volt or more) and, eg, a Belles 150A reference, with an input sensitivity of 1.4 Volts, and a volume control on the TAD, will it be necessary to get an attenuator on the inputs of the SS amp to equate the 2, since adjusting the output of the TAD will still make it less than the higher powered amp? Is 60 WPC tube power enough to drive the major energies above 800 Hz, which is where mid-range and highs predominate? Is this correct or is there another way of attenuating the input of the higher powered amp? (Not interested in playing with additional or active crossovers. Only in "simple" remedies". Or does someone know of a comparable quality amp with an input sensitivity of 1 volt? I have the TAD-60 and am looking for a suitable SS amp with at least 150WPC with sound similar to the Belles. Unless you all tell me that the TAD-60 is not powerful enough to provide power above 800 Hz to such an insufficient system,then I will look further.
springbok10
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Well, I'll tell you what. You can measure all you want to but that isn't the right way to do this. I do exactly what you seek and have messed with several combinations and have tried every way myself. This is assuming you are still going to try some horizontal biamping which it sounds like you might from your last post....

If you look at a typical frequency response of a system in a room, the bass can be very lumpy - like 5 or even 10dB humps and dips. Making sure the amps' outputs are matched to 0.5dB won't help when your response is many times worse. Besides, there are several ways you can calculate all this but it isn't clear that will help you either.

You will have to use your ears and you will need some volume control on one of the amps. This is the only way - trust me, I have been there and done that. This way you can find the right balance between bass and the rest for your room.

But you have more fundamental issues that need to be addressed first. First, your speakers are not the right candidates. It will be just too hard to find amps that will work with an 800Hz crossover point. IMO, but you are welcome to try your heart out!

Second, your speaker's crossover and sensitivity leads me to believe they are 2-way speakers. If so, horizontal or even vertical biamping won't give you as much benefit as it would with larger 3-ways.

I think your best bet is to find one nice amp you like and stick to that. If you recycle the money for the two amps into one very nice one, I bet you will be much better results far easier, provided the rest of your system is also up to par.

Arthur
If you want to match the gains of two amps this mean that there is no difference. So the logical thing is to measure the difference. This would be the voltage between the hot output terminals of the two amps. If one amp has a gain control you can achieve a very accurate match simply by adjusting the gain until the meter reads zero. If you want to measure what the gain difference is using the (small)differential measurement along with the (large) output voltage measurement will be more accurate than comparing two large output measurements.
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