How many people on this forum own an Anthem AVM 20? (1 Viewer)

[Evan S]

Ron, when did yours come in? Congrats...you will love it.

 

[Ron Alcasid]

I got it yesterday, waited five weeks. It was worth the wait! The AVM 20 sounds awesome and it's built like a tank. I'm running balanced cable to my Active 40s.

 

[Mike Thomas]

Looks like I am #9 , just picked it up today after 5 weeks of waiting. Will hook up tonight after work. I took a vacation day tomorrrow to play at home.

 

[Mifr44]

Okay, here's an off-topic question about the Anthem AVM-20 for everyone. Actually, this could apply to just about any other preamp/prepro. I have been reading that it is desirable to have a low output impedance on the preamp outputs as this will allow longer IC runs and reduce any high-frequency rolloffs.

So, why is it in our system the AVM-20, with its' 300 ohm (single-ended) impedance, gives us better and more realistic high-frequency output than either the Lexicon MC-1 (@100 ohms) or the Bryston BP-25 (@110 ohms) did? The Integra Research RDC-7 is @ 470 ohms, higher than the prepros I have listed, yet it too is highly acclaimed for music.

I understand that pure numbers don't tell the whole story, but I am just curious why the AVM-20 and RDC-7 are well-liked prepros for music despite rather high output impedance levels.

Michael

 

[BruceD]

Michael,

Could a design methodology loke this be part of the reason?

"All Inputs And Outputs Are Buffered, Which Isolates Them To Reduce Potentially Detrimental Sonic Impact From Cable Variations, Differences In The Impedances, And The “Load” Presented By Connected Components"

 

[brucek]

Michael,
You and I have talked about this issue quite a bit in the past. I'll revisit some of those issues for other peoples benefit.
I don't think you can really consider 300 ohms output impedance of a processor that significant when you consider the short interconnect cables (in the order of one meter) that most people use.
The interface between a preamp and power amp is a line level, high impedance connection, where the output impedance of the preamp is usually in the order of about 50 ohms to 150 ohms and the input impedance of a power amp is in the order of 10Kohms to 50Kohms.
This is known as a voltage bridge connection where the preamp is acting as a voltage source and almost no current is drawn. In fact, a perfect voltage source would have an output impedance of zero ohms at all frequencies. This would result in all the output voltage from the preamp being dropped across its load (the power amp) with no voltage being lost to the output impedance of the pre amplifier.
Output impedance is basically the internal resistance of the amplifier seen at its output. The value can be slightly frequency dependant, but either way, a low output impedance is desirable.
In its simplest terms you can view the internal resistance of a preamplifier and its load (power amp) as a voltage divider. The higher the output impedance of a preamplifier, the more voltage will drop across it instead of its load (the power amp).
If the input impedance of a load device is not significantly higher than the source impedance, the signal will be reduced or "loaded down" and its signal to noise ratio and frequency response will suffer.
A high output impedance requires close attention to cable lengths as you have mentioned. The concern is that the high reactance (frequency dependant resistance caused by capacitance) of the longer cable, combined with a high output impedance of the preamp, creates a low pass filter which adversely affects bandwidth. This distortion of the higher frequencies increases with higher output impedance's.
So, here's the rub. Unlike speaker cables where we don't give a darn about capacitance, with an interconnect it becomes important no matter what the output impedance, although the situation is exacerbated with a higher output impedance. Capacitance results in a reactance (frequency dependant resistance) that will roll of the higher frequencies. It becomes more and more a factor, the higher the output impedance becomes. This interface is actually the same as the connection between a source like a CD and the input impedance of a preamp, so the same rules apply there too.
This is why they insist when you use a "passive" preamp, that you use super short, super low capacitance cables, because they have fairly high output impedance's (usually 1500 ohms +). This usually varies too because the output is connected directly to a potentiometer that alters the output impedance as the dial is turned - pretty undesirable. People weigh this off against the benefit of low noise of the passive preamp.
Tubes preamps also have horribly high output frequency dependant impedance. This is what gives them that "warm" sound you hear about, actually it's distortion - oh well, each to their own. Cables are very important to valve lovers for a reason - yuck............
Anyway, there's an old rule of thumb that says, the input vs output impedance of a voltage bridge interface should be a minimum of 10:1. That's minimum. It should be greater in a high end system to ensure high frequency preservation. So, if I feed a power amp with 10Kohm input impedance I would just be OK with 1000 ohm output impedance, but I certainly wouldn't want to split that signal.
The Anthem has a balanced output impedance of 600 ohms and a single ended of 300 ohms.
Anyway, 600 ohms isn't that high, in fact, it's used a lot in recording studio and broadcast equipment. Usually in consumer equipment you'll see around 100 ohms used. Feed that 600 ohms to a power amp with an input impedance of 50Kohms and you can run some fairly long cables without any problem.
If you take a typically "good" interconnect with a 25pf / foot capacitance, then a 3 foot cable would realize a parallel reactance of about 106Kohms at 20Khz (worse case). This is very high and can be considered fairly insignificant in relation to a 300 ohm output impedance and a power amps input impedance of about 25Kohms. No high frequency rolloff will result.
But, if I used the same cable and ran it 50 feet, then at 20Khz the cable would be introducing a reactance of about 6.3Kohms. You now have to start watching your output impedance. You can do the voltage divider math.
So, I don't consider the 300 ohms of the Anthem out of line really. Any reasonable cables won't be interacting with that impedance.
The fact that so many people seem to like the Anthem AVM-20 is not likely influenced by its slightly higher output impedance. It's probably just a good processor.....
brucek

 

[AVspec]

Whooooo... Waaaiiiittt a minute.... so... let me get this straight...., Michael M. you like the sound of the AVM 20 better for movies then the Lex MC1? I have been seriously considering getting a DC-2 as I have a nice 7.1 speaker setup in my HT and thought it would pair up nicely. But now I get this statement??? I take it you compared logic-7 to some 7.1 mode on the AVM 20? I would like to here a bit more about this if you would not mind?

I really would like to get a Pre/Pro with balanced outputs and I think the AVM 20 might just fit nicely into my system but I want to make sure I get the best 7.1 bang for my buck.

Also I remember reading something about “true balanced outputs”??? I am not sure if that was with the AVM 20 or RDC-7 but I do not remember reading if it was ever found out if they were indeed true balanced connections???

Anyway great thread and keep the info coming!

 

[Mifr44]

Mark,
"Whooooo... Waaaiiiittt a minute.... so... let me get this straight...., Michael M. you like the sound of the AVM 20 better for movies then the Lex MC1?"
I like the "sound" of our system more with the AVM-20 than we did with the MC-1. But that's our system, room and preferences.
"I have been seriously considering getting a DC-2 as I have a nice 7.1 speaker setup in my HT and thought it would pair up nicely."
If you are interested in a 7.1 setup, I would still seriously consider the DC-2. Many people have had (and still have) great success with a system centered around the DC-2. Hopefully, you can get a chance to audition it, either in your home or in a properly configured 7.1 setup, before making a decision.
"I take it you compared logic-7 to some 7.1 mode on the AVM 20? I would like to here a bit more about this if you would not mind? "
No problem, but realize this is just my opinion and experience, so take it for what it is worth. We did not make our decision on how the two units compared for movies. Our main criteria was musical sound, and that's where we liked the AVM-20 a great deal.
I like Logic 7 a lot for 2 channel movie sources (i.e. cable, VHS, etc.), which is something I will miss for front-back, left-right panning. Hopefully, DPLII will be a suitable substitute for Logic 7 for us, although this is not critical. We only have a 5.1 setup, but briefly tried a 7.1 setup. While it did not help our music enjoyment, it did add to the envelopment of Logic 7 for movies.
Good luck in your search!
Michael

 

[John Tompkins]

We only have a 5.1 setup, but briefly tried a 7.1 setup. While it did not help our music enjoyment, it did add to the envelopment of Logic 7 for movies.

I would say if music is your first priority then go for the anthem. Also if you are only going to use 5.1 then again go for the anthem. The last comment about 7.1 logic 7 adding to the movies experience is HUGE for me and is worth the price of admission all by itself, threw in the lexs tweakabiltiy and music logic 7 channel and it was a no-brainer for MY needs and wants. I guess it really depends on what the persons priorities are. If I want really great two channel sound I will add the sony ta-p900es which is class a and would be very hard to beat by any ht processor for music in my opinion.

 

[Ron Alcasid]

The AVM 20 does have true balanced outputs.

 

[Evan S]

Ron, you are wrong about that. The Anthem has balanced outputs, yes, but internally the Anthem is NOT balanced. I think this is what Mark was referring to. In order to balance internally, the price would be through the roof. A Sonic Frontiers rep e-mailed me on this issue a while back and stated the AVM-20 was NOT truly internally balanced.

 

[Ron Alcasid]

Evan, that is what I meant. The Anthem has "true balanced outputs" meaning it gives you the benefits of balanced connectors but the AVM 20 does not employ balanced circuits internally. After comparing both balanced and unbalanced cables. I don't think it made such a difference it my situation. I've got 20 ft. cables to my Active 40s and Active/CC. For much longer runs it may make a difference.

 

[Dean_Sol]

Add me to this list since Nov 01!!!! Thank god I didn't take more time to wait for the 950!!!

Also, anyone know the latest on the update that is supposed to be coming from Anthem? Thanks!

Dean

 

[ManojM]

I talked to Anthem last week about the upgrade. They stated that it has been pushed back to end of May-June.

 

[Dennis Oblow]

So Dean makes #10

 

[Evan S]

There is a huge 7 page review of this unit in this month's Stereophile Guide to Home Theater. Another glowing review, but I don't have a link to it.

 

[Ron Alcasid]

Here is another review (PDF) by Quebec Audio.

 

[Joe Ar]

Looks Like I'm #11
Picked mine up on Saturday and hooked it up on Sunday but I really haven't had a chance to really use it with the holiday and everything...
I got some questions already but they will have to wait until I get some more time (Work server down):frowning:

 

[Jeff Keene]

Just ordered mine. Make mine Silver.

 

[Bill Wilkins]

Ordered mine today, black face plate or silver depending on which one will be quicker.