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8260 analog input - input impedance

milofix, modified 8 Years ago.

8260 analog input - input impedance

Youngling Posts: 13 Join Date: 6/10/12 Recent Posts
On the analog input of 8260. What is the input impedance of this speaker?
The bass are driven by ice-power amp that have low input impedance but in between there are a A/D and D/A converter.
The reason for the question is that I want to be sure before buy that my preamp will match the speakers in a good way.

Milofix
ilkka-rissanen, modified 8 Years ago.

Re: 8260 analog input - input impedance

Yoda Posts: 2564 Join Date: 3/23/09 Recent Posts
Hi,

Input impedance is approximately 10 kOhm (balanced).
milofix, modified 8 Years ago.

Re: 8260 analog input - input impedance

Youngling Posts: 13 Join Date: 6/10/12 Recent Posts
Thank you Ilkka!

10Kohm input impedance of the speaker is quite low.
Do you have recomendation of extra ordinary low output impedance preamps to drive the 8260? I mean in the best optimal way.
Some examples.

Had a ARC RefII mk 2 linestage but that had retty high output impedance 400ohm (Balanced tube direct out). The factor between output impedance of linestage and the input impedance of the speaker would then be 10000/400=25. Wonderful linestage but I sold it due to matching issue.
Another preamp 113Ohms output impedance. The factor as calculated above is then higher 88.4.
other preamp 100ohms output impedance. The factor from above are then 100.

In theory a pretty good match would be to have a factor of at least 200 between preamp/speaker, then there would be minimum risk of distorsion and frequency deviation in the frequency range. That means a preamp with max 50ohms output impedance. Have not seen that meny with such low output impedance.

What is your experience and comments on this?

Milofix
ilkka-rissanen, modified 8 Years ago.

Re: 8260 analog input - input impedance

Yoda Posts: 2564 Join Date: 3/23/09 Recent Posts
Hi,

The input impedance of an active monitor loudspeaker is essentially resistive. It can easily be driven from most preamplifier outputs having an output impedance not much more than 100 ohms. This is typically the case. A typical preamplifier output is a voltage source with a relatively low output impedance.

When the load impedance presented by the active monitor is resistive, the input signal will experience a reduction in level. If the output impedance of the preamp is 400 ohms and the input impedance of the monitor is 10 kOhm resistive, the signal is attenuated by 20 log10( 10k / (10k + 0.4 k)) = 0,34 dB. This is relatively constant across all audio frequencies unless the output impedance of the preamplifier changes significantly as a function of frequency. There is very small reactive part in the input impedance. This means that there is usually no need to make the preamp output impedance very close to zero in order to control with high damping a large reactive load.

Because the load impedance presented by the monitor is largely resistive, there is usually no danger of distortion or frequency deviation because of the properties of the active monitor input.

Typically the amplifier output impedance is used to damp the very largely reactive impedance presented by a passive loudspeaker. This is not a consideration in the case of an active loudspeaker.
milofix, modified 8 Years ago.

Re: 8260 analog input - input impedance

Youngling Posts: 13 Join Date: 6/10/12 Recent Posts
Thank you Ilkka!

My new preamp are on its way :-)

Br Milofix