Request for pro amp reviews

[cpp]

The Classes was hooked to the 800D. Both the 800D were making that hiss noise. The 802D were hooked to the Rotel amp, which didn't seem to have the hiss, at least not from 1ft away. I didn't place my ear by the tweeter on the 802D/ Rotel.

Something odd here. The last time I heard these R2D2 speakers, they also had Classe amps hooked up ( Classé Omega Omicron monoblocks), maybe it's because B&W Group Ltd makes Classe and Rotel. PS, what did sound good with the 802D with no hiss was a McIntosh MC-501. Of course I can't afford any of this stuff without going through divorce court first and then after me losing in court I would be listening to a CD through some Bose system

So enjoy when you get them ADTG

 

[AcuDefTechGuy]

Are you using the rca's? If so get some XLR to rca adaptors and that should get rid of any noise. I like the look of the XTi 2 Series better then the XLS, tis what I'm getting for my setup.

Have you actually tried this yourself and it worked, or is this just an idea?

I do have 5 XLR-RCA cables in the closet. But the SNR & gain between balanced and unbalanced is usually insignificant. So I don't see how it would completely remove the hiss.

But I guess I could try this.

 

[AcuDefTechGuy]

I guess most of us associate true high-end quality amp as one that is dead silent (no hiss). ATI amps are one such animal.

And if the amp has hiss noise, even if the amp is expensive (Classe, older Mark Levinson), most of us consider it "lower quality".

I don't think we could hear the difference in SQ most of the time. But we still classify them.

 

[Gordonj]

Have you actually tried this yourself and it worked, or is this just an idea?

I do have 5 XLR-RCA cables in the closet. But the SNR & gain between balanced and unbalanced is usually insignificant..

Just looking at the spec for the current ATI amps, the input gain between the RCA inputs and the XLR inputs is 6dB. That is very significant for the input stage. I know that your ATI's don't " hiss" but that is a big difference in gain. In this example while you would not gain anything from the cable adapter (a non-balanced input to a balanced input) you would gain form the change in the gain-stage.

That change on some amps might eliminate the "hissing".

Gordon

 

[Gordonj]

I guess most of us associate true high-end quality amp as one that is dead silent (no hiss).

All high end audio should not hiss, but I think maybe you are blaming amazing amplifies for "hiss" that is caused by a bad gain-stage. Garbage in - garbage out....

Gordon

 

[AcuDefTechGuy]

Just looking at the spec for the current ATI amps, the input gain between the RCA inputs and the XLR inputs is 6dB. That is very significant for the input stage. I know that your ATI's don't " hiss" but that is a big difference in gain. In this example while you would not gain anything from the cable adapter (a non-balanced input to a balanced input) you would gain form the change in the gain-stage.

That change on some amps might eliminate the "hissing".

Gordon

I'll try it out.

 

[Gordonj]

I'll try it out.

May the force be with you!

Gordon

 

[AcuDefTechGuy]

May the force be with you!

Gordon

Oh lord, have mercy!

I'm betting you guys are both wrong, but we will see.

 

[Irvrobinson]

Oh lord, have mercy!

I'm betting you guys are both wrong, but we will see.

Me too. I have used nothing but balanced connections for many years, and some amps hiss and some don't.

I do agree that high-gain amps like the Emotivas (rated at 32db of gain) can cause issues in some systems. I like to see 25-27db of gain. I'm also noticing that some amplifier designers are getting a bit sloppy with input impedances, with ratings of 10K ohms, and I've wondered if that could have an effect on some weak source output stages too.

 

[Gordonj]

Me too. I have used nothing but balanced connections for many years, and some amps hiss and some don't.

I do agree that high-gain amps like the Emotivas (rated at 32db of gain) can cause issues in some systems. I like to see 25-27db of gain. I'm also noticing that some amplifier designers are getting a bit sloppy with input impedances, with ratings of 10K ohms, and I've wondered if that could have an effect on some weak source output stages too.

Ok then, if it is the amps fault for the hiss then it should generate the noise no matter the input. So, unplug all the inputs and see if the hiss goes away. If it doesn't go away then it is indeed the amp. If it goes away then it is either your source or the input stage increaseing the noise floor of the input source.

Here is a short paper on gain stage - http://crownaudio.com/pdf/amps/137467.pdf

Gordon

 

[Irvrobinson]

Ok then, if it is the amps fault for the hiss then it should generate the noise no matter the input. So, unplug all the inputs and see if the hiss goes away. If it doesn't go away then it is indeed the amp. If it goes away then it is either your source or the input stage increaseing the noise floor of the input source.

Here is a short paper on gain stage - http://crownaudio.com/pdf/amps/137467.pdf

Gordon

That paper applies to situations with mics, instruments, mixers, long cables, and whatever, and is why good pro audio amps have level controls, and is less applicable to home audio systems. And it's also why most home amps get away without level controls.

I *know* the hiss with my previous amps was in the amps, because I used the same sources on the new amp and I couldn't hear any hiss.

 

[Gordonj]

That paper applies to situations with mics, instruments, mixers, long cables, and whatever, and is why good pro audio amps have level controls, and is less applicable to home audio systems. And it's also why most home amps get away without level controls.

I *know* the hiss with my previous amps was in the amps, because I used the same sources on the new amp and I couldn't hear any hiss.

Even though that paper is for amps with level controls the pincipals still apply to all systems and all amps. If it was the amps fault and it generated it's own bad noise floor it should generate that same noise all the time regardless of the input. I would not be surprised if the "hiss" was generated from a hot input stage.

The amp that was switched to and the "hiss" went away could simply be a less sensitive input, thereby lowering the noise floor.

Gordon

 

[AcuDefTechGuy]

Ok then, if it is the amps fault for the hiss then it should generate the noise no matter the input. So, unplug all the inputs and see if the hiss goes away. If it doesn't go away then it is indeed the amp. If it goes away then it is either your source or the input stage increaseing the noise floor of the input source.

Here is a short paper on gain stage - http://crownaudio.com/pdf/amps/137467.pdf

Gordon

Yes, I've always unplugged everything from the amp when checking the amp hiss.

 

[AcuDefTechGuy]

Me too. I have used nothing but balanced connections for many years, and some amps hiss and some don't.

I do agree that high-gain amps like the Emotivas (rated at 32db of gain) can cause issues in some systems. I like to see 25-27db of gain. I'm also noticing that some amplifier designers are getting a bit sloppy with input impedances, with ratings of 10K ohms, and I've wondered if that could have an effect on some weak source output stages too.

Well, the ATI AT3000s have a 34dB gain. But they are still dead silent. Even when I crank the Denon volume to +17.0 (in STOP mode, of course).

 

[Irvrobinson]

Well, the ATI AT3000s have a 34dB gain. But they are still dead silent. Even when I crank the Denon volume to +17.0 (in STOP mode, of course).

The sensitivity is lower when you use the balanced inputs, like I do.

 

[Irvrobinson]

The amp that was switched to and the "hiss" went away could simply be a less sensitive input, thereby lowering the noise floor.

Gordon

The two amps have nearly identical gain. The gain of the Levinsons was 26.8db, while the ATI's gain is 28db.

 

[Adam]

I've lost track - is there a consensus (or opinion) on which pro amp(s) we'd like to see tested?

 

[fuzz092888]

Whatever ADTG votes.................I vote something different

 

[AcuDefTechGuy]

I've lost track - is there a consensus (or opinion) on which pro amp(s) we'd like to see tested?

Crown, of course, since it is Harman International and since Lexicon's 8ch amp is the same 8ch Crown amp.

But which model? I think the XLS since it is probably best value. The XLS 1500 is $350 regular delivered price (cheaper on sales) and is 300wpc x 2ch 8ohms.

 

[AcuDefTechGuy]

Whatever ADTG votes.................I vote something different

Why.................you.

I'm usually very sound minded and reasonable.