ATC scm 19 upgrade ??

atc don´t sound good at low levels and my home studio
is very small.

So you like the neutrality, accuracy, dynamics, image and soundstage but
something is obviously wrong at low levels? Is it the lack of bass from the sealed
box? Is it something else? FWIW: If you play at volumes lower than normal then
you must expect it to sound bass light (equal loudness contours). If this is the
problem then a ported design (with more bass to begin with) may better suit
your need (such as a Dynaudio or Totem or Harbeth). Harbeth have nice mids
and a warm bass - ideal for great sound at lower levels where bass tends to be
lost.

BTW, ATC and Bel Canto make a marvelous combination.

I haven't tried so I really can't say either way - although Bel Canto has the power needed and it is a respected brand. I think the dealer above is mostly concerned about Class D amp design and lets face it - nearly everyone has an opinion or bias on amp design (from tubed single ended to Class D everyone seems to have their preferences). I suspect however Powerstudio's problem is more with the speaker as I would not be surprisedto hear that he has already checked it with another amp - at low levels in a near field position you are only going to need 40 watts.

In my experience source problems with ATC tend to show up more at loud levels - digital hash, a poor recording, amplifier distortion all become annoying due to the forward midrange (like with a horn you hear it - nothing is sugar coated).

Another caveat is that, as a general rule, louder (as long as it remains without distortion) always sounds much better. This makes it hard to listen without inching up the volume. Inevitably, ATC users nearly always end up listening at louder SPL's than those with other speakers. Some people say it is the way they are voiced (light bass) whilst others argue it is because they don't distort as much as most speakers. Perhaps it is a combination of both.

Along these lines, however, it would be nice to know what source Powerstudio is using or has tried?

Powerstudio,

You appear to be working at quite low SPL's (far less than 70 db). At lower levels it should be nearly all midrange and as you go higher in SPL the treble and bass should become more prominent. Something is indeed unusual or plain wrong.

Try to run some tests at different SPL levels (what you mix at and what "sounds good") to see what you are experiencing in your room with your gear.

This may help you confirm what you have described - right now I think a ported speaker with more bass output is on the cards.

FWIW: Another angle to pursue is that the Cranesong Avocet is described by Bob Katz as being similar to Benchmark DAC1 - this suggests soft or 'missing' lower midrange (according to benchmark manual that is what most people perceive the DAC1 to sound like compared to other DAC's).

FWIW2; See Equal loudness curves. Notice how bass and lower midrange (500 Hz) drops in sensitivity as you go to lower SPL's (from 70 to 20 db SPL) - relative to the all the other frequencies.

Avocet can be similar than benmarch but avocet is far superior used in hundred of mastering rooms

I did not mean to imply Avocet is comparable in quality to DAC1 - I just read Bob Katz review thats all. I don't know this Avocet at all - so I simply googled it and found that Bob Katz says, "So, what does the Avocet sound like? For digital (PCM) sources, its DAC sounds indistinguishable from the Benchmark, one of the best DACs I’ve heard regardless of price"

I usually work at 65/70db but I feel important change from 70 to 68/65(1 steep down in avocet)

=> In this case something is wrong for sure. I don't think it is a speaker choice problem - something is broken or not operating correctly. If the image moves slightly then you can suspect one channel or the other in the chain - it could be speaker, source or amp or coupling between source and amp. FWIW: If you are controlling the volume with the Avocet then extremes in attenuation are best avoided as that is where any volume control is usually at its worst. If there a way you can attenuate the Bel Canto (does it have trim pots?) so that you drive the Avocet higher in line level signal into the Bel Canto then that would be the next step that I would try. Volume attenuation does strange things even with high end gear when at extremes - it can affect noise floor, dynamics, imaging and frequency response in subtle ways.

How do you connect your atc´s ? bi-wiring?

My passive 20's are the old kind with no biwire posts ('95 model). I run monster cable from the power amp to the binding post - no spades on either end but everything good and tight.

The reason I warn you about extreme volume attenuation is because if you listen close near field (0.5 meters sitting at a computer workstation) then you will get about 91 db SPL at for 1 watt from the speakers. If you listen at 65 db SPL then you are talking 2.5 milli-Watts to the speakers. If you source music is really good or excellent from a raw recording and uncompressed (say 60 db of dynamic range) then the lowest audible signal (in theory) is 2.5 nano-watts.

These signals are starting to get very small - you may be bumping into non-linearities of electronics and or speakers at these levels.

There should be attenuator trim pads or something like that go between your Avocet and Bel Canto S300. That way you can run things with the volume contro at 2 O'clock instead of 8 or 9 O'clock.

Sorry if this is all ho-hum to you as you know all this already.

Wonderful_electric,

That is also a good suggestion - certainly it woudl be easy to borrow another amp and test again at these low levels even a 20 watt amp would be more than enough. In "theory" Class A is better at very low volume levels. That is how my ATC amps in the amp pack run - Class A to 2/3 power. In practice, most Class AB can do very well - some would say indistinguishable given good quality. I am not sure if Class D has established a reputation one way or the other but in "theory" it should be good too (provided the ultra-high frequencies are all filtered out and nothing gets into the audible band - kind of the same issue as with a DAC). Class D, in "theory", should be capable of producing exceptional linearity - just like digital. Since I have no hands on experience of Class D I really can't comment - but several people on Audiogon have spoken positively about this type amp (based on B&O design I believe)

Powerstudio,

If you take a look at this thread then you will see what I meant about volume control. Simply read what Elias Gwinn has to say about a potentiometer volume control in the first post at the top - it is best used in its "upper 80%" and should not be used in its lower "20%". That would be my rule of thumb too.

My preamp has a resistor ladder. My DAC has a pot! The resistor ladder on the preamp (Crystal 3310) is in "theory" better - so I simply run the DAC at full output (volume up all the way) and use the preamp to attenuate (besides I am lazy and really like to be able to use a remote!!!).

I suspect that many unhappy experiences with some gear may be partly related to this issue (and not the fault of the gear itself).

FWIW: I could not determine how the Avocet controls volume. If it uses a resitor ladder like the Crystal 3310 (used by Bel Cantyo, Jeff Rowland and many others) then it could be equally as good at 9 oclock as it is at 2 PM.

Of course, most people don't have the benefit of an engineering degree and are unaware that volume control can be a bit of mine field. 140 db of dynamic range of volume control sounds small ...but it is a multiplier/divider with numbers with TEN+ of zeros after them (if you are an engineer then you start to feel sorry for the poor electronics which are expected to have such linearity in two channels)!