1800R

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trebejo

1800R
« on: 5 Apr 2012, 07:35 am »
Some weeks ago, a second 600R arrived to join its lovely twin. Thanks to the phase inverter option in my AVA preamp (Avastar), I was able to set these up as monoblocks, essentially obtaining something like triple the power of a 600R.

Now it's not as if I really needed that extra power. Through the 15" Tannoys, the volume knob rarely gets to 9 o'clock--and that's with a generous helping of digital equalization, without which even 8 o'clock is starting to get kinda loud.

So as far as I can tell, the monoblock setup is not really supplying needed extra power. And yet, there is something about walking as far away from the speakers as possible, putting the knob around 10 or 11 o'clock and experiencing that. Here it's always a brief experiment.

Another brief experiment is that Mahler moment, when the relatively quiet orchestra summons up a collective effort and the decibels scale up fast and solid. With the monoblocks, there's that extra bit of confidence that, well, no straining will take place before the signal reaches the loudspeakers.

Now, onto the real reason to even do this. As bloody excellent as things are with a single 600R, they get a bit better with two. I think the official terms for this effect are lower noise floor, greater stereo separation and stronger bass control. Yes, I would say it's true. It's ridiculous, since one already gets very healthy helpings of all that from a 600R (and the phase inverter even allows the noise floor lowering with a single amp). Nonetheless, the effect seems to be there.

Obligatory music listening reference with the 1800R: I'm listening to Abbado conducting the Wiener bunch through Mahler's 4th (von Stade sings the last movement). I've been listening to this recording since I discovered a couple of decades ago that the CSUN library would let you listen to their CDs through their headphones and DAC while you read whatever functional analysis book you could find on the shelves (our California tax dollars at some of their best work). This particular CD is beyond memorized for me, I feel that a good geneticist might find it in my chromosomes by now. Well, yes, it's true, even with this little bit of a euphonic bit of nothing that Mahler put together just because he felt like making something pretty, even here one can hear new harmonic nuances in the resonance of background strings, a further level of sharpness, definition and spatial correctness in the percussion section... all of which leads to greater layering in what is already a very well-layered musical experience.

Is it worth the $$$? Well, I had an extra 550 sittin' 'round doing nuthin' so I felt a kind of "moral obligation" to do it. If eternal salvation came at the cost of living with a single 600R then I would sign on the bloody dotted line without a moment's thought, but if the price is somewhat lower than that, hmmm...  :scratch:

One thing is clear--now that they're both plugged in, there's no way I'm breaking them up. These 600R are joined at the phase-inverted hip from now on.

<sigh> It's a familiar tale by now, you probably know it by memory... things sound fantastic... you can't imagine how they could get better without major overhauls to your room, or a trip to the concert hall... then lo and behold, something gets upgraded and there was a bit of room at the top after all. Monoblocking the 600R into an 1800R will give you many such moments.

The nice thing about getting stuff from Frank & AVA is that you pretty much draw the experimentation line at your loudspeakers. Move them around, change them, it all produces variety and even improvement. But tracing things back from the amp to the preamp and the DAC, I find it really easy to just smile and think "well, no need to worry about those guys there, things are quite solid there".

Congrats Frank and crew, it's a lovely setup I've got here and it wouldn't have happened without ya.  :thumb:

NIGHTFALL1970

Re: 1800R
« Reply #1 on: 5 Apr 2012, 10:05 am »
Trebejo,
Can you please post some nice large pix for us so that we can drool?

 :drool:

PSB Guy

Re: 1800R
« Reply #2 on: 5 Apr 2012, 06:26 pm »
+1. I would also love to see pictures, Trebejo.

Cornelis

pardales

Re: 1800R
« Reply #3 on: 5 Apr 2012, 06:34 pm »
Wouldn't it be a 1200R....600x2?   :D

Tom Alverson

Re: 1800R
« Reply #4 on: 5 Apr 2012, 06:46 pm »
Wouldn't it be a 1200R....600x2?   :D

No, when you use an inverter on the second channel and connect the speakers from Left-Red to Right-Red you are doubling the voltage.  The power is the voltage squared divided by impedance, and since the voltage is doubled, the power is 2 squared (4 times the power).  So instead of 300W from one channel you can get up to 1200W from a bridged amp (if it can supply the current to do this).  So if no current limit existed a pair of these would be 2400W total, but most people use 3x the power for this arrangement as a typical result.  It's probably closer to 4x with the 600R since it has very high current capability.

trebejo

Re: 1800R
« Reply #5 on: 5 Apr 2012, 08:06 pm »
Trebejo,
Can you please post some nice large pix for us so that we can drool?

 :drool:

Sure, here's the whole rig,



(yes, the Tannoys are upside down, they sound better that way given this setup but when I get the proper height for a stand then they'll probably go back upright), and here is a close up of the AVA quartet (Ultradac II, Avastar, and a pair of 600R),





btw the innards of that cabinet are noticeably cooler now that the 550s were upgraded to 600R.

Tom Alverson

Re: 1800R
« Reply #6 on: 5 Apr 2012, 09:18 pm »
btw the innards of that cabinet are noticeably cooler now that the 550s were upgraded to 600R.

I noticed the same thing.  The 550 ran pretty hot after the double upgrade.  That made sense since it had twice the number of output FET's and the bias per FET was probably the same.  The 600R runs much cooler for whatever reason.

aln

  • Jr. Member
  • Posts: 248
Re: 1800R inverter
« Reply #7 on: 10 Apr 2012, 12:33 pm »
Is the inverter built into the preamp or seperate?

PSB Guy

Re: 1800R inverter
« Reply #8 on: 10 Apr 2012, 06:08 pm »
Is the inverter built into the preamp or seperate?
According to his system shortcut, it's built into the Avastar pre.

Cornelis

NIGHTFALL1970

Re: 1800R
« Reply #9 on: 28 Apr 2012, 02:48 pm »
Trebejo,
Can you listen at lower volume levels and not lose dynamics?

trebejo

Re: 1800R
« Reply #10 on: 28 Apr 2012, 06:09 pm »
Trebejo,
Can you listen at lower volume levels and not lose dynamics?

In the spirit of your question, I would answer "yes". One can actually get accustomed to 70 db peaks and the like, and it seems as if no musical information is lost.

Nonetheless, louder is always tempting... :rock: