Amp recommendation for $75K system

[VladP]

I think there is some confusion, I am not going to spend $75K but rather was referring to the amp in the AH $75K system. Though my system will ultimately be expensive too.

Finally some info on the Dreadnaugh III. The problem I have with the Thetas is their power consumption in standby mode, this is a deal killer for me. In the configuration I would want the amp uses 160W in standby ... and no, I'm not willing to use the power switch when I can use an external trigger instead.



No doubt the XPA-1 is the top of the line for Emo... but the space required for monoblocks and a $7K investment would lead me to look at alternatives. I don't need 500W of power.



The only better specs I see are the charts which are supposedly provided by Emotiva. I don't believe the THD+N chart, typically if you include noise it would increase with freq. I also don't see how taking a two channel amp and using it as one differential amp can reduce distortion. You can cancel noise but not distortion. Each half of the amp would still contribute the same amount.

I called Emotiva and they told me the distortion figures are about the same. I can't find two figures from Emotiva that agree or that were measured the same way, so really don't know what to think.

I don't know. The graph presented by Emotiva are actual measurements. At some point, they said that they will provide similar measurements for all of their amps but they never have.

So I am just going with their measurements and very similarly presented measurements by Secrets for XPA-2 - and comparing these two they look very different. If you read the review on the secrets they compare xpa-1 to rpa-1 which also shows very low distortion. Gene, on the other hand, mentioned that rpa has much lower distortion compared to xpa-2.

I also read some discussion of xpa-1 on the emotiva forum and both Dan and Lonnie very explicitly talk about very low THD in xpa-1.

So I don't know. The measurements provided by Emotiva for xpa-1 look real and not fake to me, but I do agree with you that when Emotiva posts average measurements they seem to change from place to place. That is why I like actual measurements linked as two pdf files to the emotiva xpa-1 website - they are very specific measurements with all details provided separately for 8 ohm and 4 ohm.
http://emotiva.com/xpa1/xpa1_8ohm.pdf
http://emotiva.com/xpa1/xpa1_4ohm.pdf

If xpa-2 indeed measures similarly then xpa-2 is simply a phenomenal amp.

 

[AcuDefTechGuy]

the Quad 909s will best the lot of them.

I know that 100 watts per ch into 8 ohms is probably more than enough.

But I think 200 or 300 watts/8 ohms would look a lot better, especially for high-end.

By the way, remember that Acurus amps' lack of speaker protection circuits?

Well, Indy Audio Labs just bought Acurus & Aragon and they are suppose to come out with new Acurus & Aragon products in 2010!

 

[VladP]

I know that 100 watts per ch into 8 ohms is probably more than enough.

But I think 200 or 300 watts/8 ohms would look a lot better, especially for high-end.

100 wpc is not enough for B&W802D or 803D so that amp is not really an alternative for these speakers IMO.

 

[AcuDefTechGuy]

What about getting a BRYSTON class-A multichannel amp w/ 20 yrs warranty?

I think it measured over 170 watts into 8 ohms and over 240 watts into 4 ohms.

Since the B&W 802Ds are 4 ohms, I think 240 watts/4 ohms would be enough?

 

[AcuDefTechGuy]

100 wpc is not enough for B&W802D or 803D so that amp is not really an alternative for these speakers IMO.

Well, that's 8 ohms. I think it's 200 watts into 4 ohms.

Of course, I would take the XPA-1's 1000-watts into 4 ohms anyday.

 

[AcuDefTechGuy]

Or what about the BEHRINGER EP4000 amp?

RMS @ 1% THD, bridged mode: 1750 watts/8 ohms & 2400 watts/4 ohms.
20Hz-20kHz @ 0.1%THD, 2ch driven: 550w/8ohm, 950w/4ohm, 1250w/2ohm.

Just keep them inside the cabinet and no one has to know what they look like.

 

[VladP]

Or what about the BEHRINGER EP4000 amp?

RMS @ 1% THD, bridged mode: 1750 watts/8 ohms & 2400 watts/4 ohms.
20Hz-20kHz @ 0.1%THD, 2ch driven: 550w/8ohm, 950w/4ohm, 1250w/2ohm.

Just keep them inside the cabinet and no one has to know what they look like.

I personally have already made my choice - emotiva xpa-1. The more I use them the more I like them. My three new xpa-1s arrive on Monday and I am all set for my 5-channel system. I really think it would be hard to get something significantly better at that price.

 

[bigred7078]

Yeah, I would buy the XPA-2 and XPA-5 in a heartbeat if they measured like the XPA-1, but then who would buy the XPA-1? More than two boxes is just too impractical for me. I suggested to Lonnie that Emo come out with an audiophile grade multi-channel amp. I would not mind spending another $500 given what their competition costs.

I can get a good deal on the Anthem amps so have been considering them... but Anthem tells me the P5 uses 340W at idle. Add the P2 and you're probably at 450W. Not very friendly on the electric bill. All other models are 150W or less so that makes the A series more appealing from that aspect. I don't really need the power of the P series anyway.

I'm an Anthem dealer, and honestly the RPA-1 holds up pretty damn nicely against the the P2

 

[AcuDefTechGuy]

I personally have already made my choice - emotiva xpa-1. The more I use them the more I like them. My three new xpa-1s arrive on Monday and I am all set for my 5-channel system. I really think it would be hard to get something significantly better at that price.

Yeah, no matter what brands I look at, I keep on going back to Emotiva as the Amps & Pre-Pros of choice.

I would not mind reserving a whole audio rack just for 5 XPA-1s + 1 Emotiva Flagship Pre-Pro.

 

[bigred7078]

I personally have already made my choice - emotiva xpa-1. The more I use them the more I like them. My three new xpa-1s arrive on Monday and I am all set for my 5-channel system. I really think it would be hard to get something significantly better at that price.

great to hear. I've been thinking about XPA-1's but don't know where the cash would come from lol, plus i dont really need them

 

[PaulF]

I have to repeat that the Quad 909s will best the lot of them. Pure class A sound without the complications such as high quiescent current consumption with high output device failure rate.

By default, any high power class A amp will have high quiescent current, it's the nature of the beast. The output stage must be biased at half the rail voltage to achieve maximum output swing.

I also read some discussion of xpa-1 on the emotiva forum and both Dan and Lonnie very explicitly talk about very low THD in xpa-1.

So I don't know. The measurements provided by Emotiva for xpa-1 look real and not fake to me, but I do agree with you that when Emotiva posts average measurements they seem to change from place to place. That is why I like actual measurements linked as two pdf files to the emotiva xpa-1 website - they are very specific measurements with all details provided separately for 8 ohm and 4 ohm.
http://emotiva.com/xpa1/xpa1_8ohm.pdf
http://emotiva.com/xpa1/xpa1_4ohm.pdf

If xpa-2 indeed measures similarly then xpa-2 is simply a phenomenal amp.

I had not seen the full report, thanks for the links. Do you have a link to the dicussion? The forum search function is kind of weak. Actually I am not saying Emotiva is faking anything, just that different measurement setups yield different results. Emotiva will have presented the best possible numbers for the XPA-1, so I would like to see their numbers for the XPA-2.

By the way, remember that Acurus amps' lack of speaker protection circuits?

Well, Indy Audio Labs just bought Acurus & Aragon and they are suppose to come out with new Acurus & Aragon products in 2010!

No protection, no-go. I've got kids . Can't wait till 2010.

100 wpc is not enough for B&W802D or 803D so that amp is not really an alternative for these speakers IMO.

I agree, they come alive with more power.

What about getting a BRYSTON class-A multichannel amp w/ 20 yrs warranty?

I am considering Bryston but one dealer told me they no longer offer 20 year warranty on new amps.

I'm an Anthem dealer, and honestly the RPA-1 holds up pretty damn nicely against the the P2

I have looked at the P2 but again 350 watts at idle and it is one massive am to which I still need to add another 2 channel. Emotive is definitely up there on the short list.

Yeah, no matter what brands I look at, I keep on going back to Emotiva as the Amps & Pre-Pros of choice.

I would not mind reserving a whole audio rack just for 5 XPA-1s + 1 Emotiva Flagship Pre-Pro.

Yeah but seven monoblocks, I would have to reinforce my floor! Don't forget that $7K for Emo can get you a $10K amp discounted by 30% which is realistic right now.

 

[VladP]

By default, any high power class A amp will have high quiescent current, it's the nature of the beast. The output stage must be biased at half the rail voltage to achieve maximum output swing.



I had not seen the full report, thanks for the links. Do you have a link to the dicussion? The forum search function is kind of weak. Actually I am not saying Emotiva is faking anything, just that different measurement setups yield different results. Emotiva will have presented the best possible numbers for the XPA-1, so I would like to see their numbers for the XPA-2.


Yeah but seven monoblocks, I would have to reinforce my floor! Don't forget that $7K for Emo can get you a $10K amp discounted by 30% which is realistic right now.

Unfortunately I don't have the link for the discussion forum. It was a while ago - sometime in October 2008. The search on their forum is a joke and it simply does not work. The only way to find these discussions is to go manually through the amplifiers section on the forum. I wish Emotiva published their measurements on xpa-2. Could you email Lonnie at Emotiva and ask whether he can provide similar measurements for the xpa-2? I would think they should have them.

$7K is a lot but I don't think you can get a comparable 7-channel amp for the same price. Classe or Mcintosh or Bryston would probably run considerably more expensive?

 

[TLS Guy]

By default, any high power class A amp will have high quiescent current, it's the nature of the beast. The output stage must be biased at half the rail voltage to achieve maximum output swing.

Not so, as I explained earlier. The Quad 909 uses a circuit patented by the late Peter Walker OBE. As I explained earlier these are what Peter called his current dumping amplifiers.

The circuits of these series of amplifiers are totally unique. Only Peter Walker ever designed such unique and cunning circuits. They are feed forward class C amplifiers to give them there correct designation.

The class C dumper stage produces the power. However there is a very accurate small class A amplifier that provides feed forward error correction to the dumpers.

Peter showed mathematically and on the bench, that the specification is dependent on the performance of the small class a amplifier, which is very good indeed. These amps are stable, highly linear and have zero crossover distortion. Peter's circuit comes closer than any other to achieving the goal of the wire with gain.

These amplifiers give prolonged trouble free life and components can wander widely from original values over time and the performance of the amps is unaffected.

I have used his current dumping amps exclusively for over 30 years now, and I doubt I would ever change to another amplifier topology. I'm in good company as the BBC have been wedded to these amps as long as I have.

These amplifiers sound really sweet and are the product of pure genius.

 

[Lordoftherings]

Any informative links and reviews on these Quad 909 amps?

Bob

 

[TLS Guy]

Any informative links and reviews on these Quad 909 amps?

Bob

None that are all that informative. Peter Walker was very outspoken about the dumbing down of audio reviews and audio gimmicks. He railed against funny speaker wire, with his famous comment "wire is wire." He had oodles of sarcasm for reviewers that made comments like "liquid midrange" etc. The result was an almost total boycott of his products by the loony press and not a little libelous badmouthing. Peter Walker was one of the greatest pioneers of audio, and as fine and honest a man as you could meet. He hated the cons that started to be perpetrated, for relieving audio enthusiasts of their cash. These specious products like $1000 AC cables are still being touted.

I will say that I have extensive test equipment. I own three 909s, and quite a few 405 2 amps, all current dumpers. I can confirm that they easily meet THD specs. There is not a trace of crossover distortion. They meet their power specifications.

Sonically the amps are entirely neutral, they are reliable, and a joy to own.

In my view there is nothing to touch them in their power class, and they provide ample power for the vast majority of domestic situations.

Here are some reviews, but they do no shed as much light on these amps as I can.

http://www.whathifi.com/Review/Quad-909/

http://www.hi-fi-insight.com/quad-909-amplifier.html

 

[Lordoftherings]

Thanks TLS Guy,

Seems that you are indeed the best link.

Bob

 

[PaulF]

TLS Guy, what you are describing makes no sense to me. I don't know if you have an electronics background, but a Class C current dumping feed forward amp means nothing meaningful to me.

The characteristic of a class C amp is that it is conducting for less than 180 degrees of the cycle, which means by default it switches off. By switching off it must go into it's non-linear operating area and therefore produces distortion. Class C amps are used in RF amps, oscillators, mixers etc. where the load is a tuned circuit and the amp operates for a short period of time to top up the energy in the tuned circuit.

Feed forward is very similar to feedback, both schemes are a method of introducing out of phase signals to reduce distortion and noise and to flatten freq. response. I don't know what is meant by current dumping.

I don't know if the Quad is a great audiophile grade amp or not but the description does not lend itself to an audio amp.

 

[PaulF]

Could you email Lonnie at Emotiva and ask whether he can provide similar measurements for the xpa-2? I would think they should have them.

Lonnie emailed me and said the reports are complete and will be posted next week.

 

[TLS Guy]

TLS Guy, what you are describing makes no sense to me. I don't know if you have an electronics background, but a Class C current dumping feed forward amp means nothing meaningful to me.

The characteristic of a class C amp is that it is conducting for less than 180 degrees of the cycle, which means by default it switches off. By switching off it must go into it's non-linear operating area and therefore produces distortion. Class C amps are used in RF amps, oscillators, mixers etc. where the load is a tuned circuit and the amp operates for a short period of time to top up the energy in the tuned circuit.

Feed forward is very similar to feedback, both schemes are a method of introducing out of phase signals to reduce distortion and noise and to flatten freq. response. I don't know what is meant by current dumping.

I don't know if the Quad is a great audiophile grade amp or not but the description does not lend itself to an audio amp.

There have been endless debates about how Peter's circuit works, but work it does. Peter told me personally that he regarded it as as Class C feed forward amp that is unique. Although Pass Labs have possibly infringed on his patents.

I see that the current owners of Quad now describe it as class B feed forward. However the point is the specs are set by the class A amp. I see on some forums posters regard the circuit as a servo amp.

Quad amps are among the most tinkered in the DIY world. Peter's brilliant circuit has provided a lifetime of fascination for many. However music enthusiasts have enjoyed his products for generations, and plugged them in and not given them a second thought for years.

I could not find a circuit on the net for the 909, but I did for his 606 which is similar.

Here is a link to the Quad 909 manual.

Here are couple of sites for the large number of Quad enthusiasts around the globe.

http://www.geocities.com/ResearchTriangle/Lab/6722/

http://quadrevisionspot.blogspot.com/

Enjoy yourself as you delve into Peter's unique amp circuits.