Hi,
Amplifier 7500 has both balance and RCA connectors. My receiver (Yamaha V861) only has RCA output. If I use RCA connectors, do I lose the advantages of 7500 designs? Do I lose the benefits of differential design for low noise and fast transient response?
Thanks,
TGreen

No

Expanding slightly on Altec's answer.

You will still reap the benefits of differential design as the input circuitry takes the input signal from the RCA connector and after appropriate buffering inverts it and feeds the original to one half of the amp and the inverted signal to the other half. The amp will still function as designed.

Actually, the 7500 does not have an unbalanced to balanced circuit on it's input like some of the other Outlaw amplifiers.

What the 7500 does in "unbalanced" mode is exactly what a conventional stereo amplifier does when you put it into "bridged" mode.

What this entails is feeding the unbalanced signal directly to the non-inverting side of the amplifier. Then the output of that amplifier is fed through a feedback resistor which is identical in value to it's own, back to the inverting node of the "inverting" amplifier side.

When the amplifier is run in fully balanced mode, this extra feedback path is bypassed and the inverting and non-inverting sides of the balanced line are fed to the two sides of the amplifier directly (since in a balanced feed one side is already inverted).

Hi,
Thank you very much for both of your response. I am glad to hear that I still reap the benefit of differential design of the 7500 when using RCA connectors. I have two follow up questions.
1. Both 7125 and 7500 amplifiers have slew rate of 50 volt/usec. It seems like that they have similar transient response. Why Outlaw Audio claims that differential design of the 7500 "near double transient rate" compared to single-end design (e.g. amplifier 7125)?
2. Altec mentioned that the 7500 does not have an unbalanced to balanced circuit as other Outlaw amplifiers. Can you please tell me which one is it? and does it sound better with this unbalanced to balanced circuit?
Thanks in advance,
TGreen

All the Outlaw multi-channel amplifiers are balanced designs - they are all variations on the same basic design. I wouldn't worry too much about absolute slew rate numbers - they are all far in excess of what you would need in any program material you would ever listen to (I'm assuming you don't make a habit of listening to full power square waves for enjoyment!).

The exact input configuration, i.e. how they drive the two "sides" of the balanced amplifier is really an academic distinction. The end result is the same. Some models such as the 7900 have an additional active stage where the signal is split between the original unbalanced phase and an inverted copy to be sent to the "inverting" side of the amplifier.

Both "halves" of the power amplifier section are identical, i.e. they are both non-inverting.

You are not likely to hear any differences in sound quality between any of the Outlaw multi-channel amplifiers.

Aren't the 7200 and 7125 7 channel amps single ended designs?

Hi,
I think there are two kinds of amps from Outlaw Audio (single-end and balance). Outlaw Audio makes pretty big claim on balance amp (such as 7500) to give a faster transient response than single-end amp (such as 7125). Can we hear the difference between them? Anyone would like to make a comment?
Thanks,
TGreen
PS: I am narrow down to either 7500 or 7125. My main question is which one has a better sonic and sound quality? Can I hear the difference between them? I am not worry about the difference in power (Watt) between them. Most likely, I only use about 50 Watt/channel.

If you don't have or are not planning on buying hard to drive speakers, I'm not sure you will notice much of a difference, if any between the two amps.

This is not based on direct experience with the two amps but similar experience of trying out B&K 200.7 and Outlaw 7700 to upgrade my Kenwood THX 6 x 100 Watt amp.

Of course having said that, having the additional headroom does have it's advantages, particularly if you ever do want to upgrade to speakers that are harder to drive.

I tested the 7125 around Christmas and during my testing the 7125 got super hot when driving my B&W 603's. I really don't know if I got a bad amp but I couldn't touch the top of it and it when into protection mode on the left channel. Now I did talk with Outlaw , tried there sugestions on the power outlet, speaker wire,and a few other sugestions. Well I sent the 7125 back got the 7500 and haven't looked back. The 7500 is the ticket for me. Good luck!!!