help me to understand the gain

04-29-11: Davehrab
The PL3's output voltage is 5 volts as measured in a Stereophile review and way to much output for the DNA1's input stage.

With due respect for your well intended comments, I believe you are misinterpreting that spec. That number represents the output voltage at which the onset of clipping occurs, as indicated by a significant rise in distortion. The higher that number the better, everything else being equal. The actual output voltage at any instant of time will equal the input voltage multiplied by the gain that is provided by the preamp at the volume control setting being used (12db being the gain corresponding to the maximum setting of the volume control).

You can put a 10db attenuator at the amp's input or just remove the PL3 and drive the DNA1 from the Dac ... which has Tube output and a volume control.

If the PL3 is used, putting a 10db attenuator at the amp's input won't work well. Bass rolloff will result, as I indicated in my previous post. It also won't be a sufficient amount of attenuation.

Good point about the volume control on the DAC, though. Assuming it is the D1 model, I note that it also includes source switching, for both digital and analog sources. I don't know what its output impedance is, but if it is low enough to work well with an in-line attenuator, perhaps ditching the preamp AND putting a 10db attenuator at the amp inputs would do the trick. The OP might want to ask the DAC manufacturer what its worst case (maximum) output impedance is, across the audible frequency range.

If it were me, though, I would seriously consider Herman's suggestion of a 300B SET amp, or other low powered tube amp.

Regards,
-- Al

I completely agree with Almarg and Herman.

I would suggest selling the amp and replacing it with something that is less powerful and has lower gain.

An SET amp would be my preference.

Wow, thank you very much for all the inputs. It seems all the parameters affects the gain, and it sounds like really my system is lacking synergy. And there is alot of technical stuff that I don't really understand, please excuse me if I ask something stupid.

It seems the gain of the amp is not a published specification. I can only see it inside the Stereophile review under measurement section. How stupid ...

Almarg, thanks for your insight about bass roll off with attenuator. I don't have the engineering background to understand the correlations between impedance and all those stuff, but I will take your words.

I really want to keep the PrimaLuan preamp. I don't have anything technical to back me up, but in my experience, the preamp has a bigger impact to the sound then the amp. And I like how PrimaLuna sound, so, I likely will keep it.

I will try to connect the DAC directly to the amp, but I will missed the PrimaLuna sound.

About the option to lower the gain of McCormack, I think I won't go that path also. It seems I will need to send the amp to Steve, it is kind of a hassle. Also, my new Zu speaker won't need such high current, so, if it is not compatible, I may sell it out and get something else.

As people can see, my Maverick DAC has a volume control as well. So, I can lower my DAC input so I can make the volume know of the preamp within a usable range. This is similar to if I lower the volume in iTunes. My question is, how would this affect the sound? Will I run into the bass roll off problem like using attenuator?

Another option is to get another amp. I would like to try the SET amp. If I want to keep the PrimaLuna, what parameters should I pay attention to? I know most of them are pretty low power, but as said, power is not the real problem. I don't think they publish the gain info. Also, does the requirement to have input impedance > 100k Ohm still applies? Maybe more straight forward, what is your recommendation?

We have an amp that has only 23 db of gain. It works really well with ZU speakers too.

The problem you are having is classic- a DAC with too much output. I don't understand why DAC manufacturers do this- to me it seems like a fundamental misunderstanding of how power amplifiers work. There is not a power amp out there that needs more than 3 volts input, so why do you need 5 or 6V?

With that kind of output you have to attenuate the signal, either by passive control, digital volume control or something like the Rothwell attenuators. *All* of them rob the signal of musicality! With digital and passive controls, the higher you can run the control the better they sound (although for different reasons). So why force the user to turn things down so much??

Enough of my diatribe- you have gotten good advice from other posts here...

Sell the Zu speakers and get another speaker with lower, say mid-80s, efficiency. You'll get more of you're money back selling the Zus, they are a hot item compared to the McCormack amp. There are plenty of fine speakers out there that like an amp with power and current.