Dirac LE - Amp Trippin'

[heroesunplugged]

I'm using the file that Socketman provided and Ansat posted. It has improved the bass for my other combinations, but think this variance between the sub output and the mains is just too much. The subs peak at about -8 dB and the mains are at about -16 dB. They're both just within the 12 dB green are for the levels.

[heroesunplugged]

Reversed the amps and the Sony with the JBL subs work great. The SA-250 supplying power to mains works better. Seems the Sony, with the lower damping factor, actually does a better job in regard to better bass definition - post Dirac. May also be attributed to the Sony not having the depth of the SA-250 at the very lowest octaves. The SA-250 is smoother and draws a more defined sound stage regardless. The fact that the JBL 15s don't play as deep, as most 12s I've had, may also make the Sony a better match. The measured -3 point is around 35 Hz after Dirac. Using the Sony's level controls helps match the levels and Dirac does a much better job. The sound is very solid and cohesive.

Talked with Keith and have done a factory reset. Noise still present through the subwoofer out when implementing Dirac, however the Sony has gain/volume controls and once lowered from full to about 95% the noise subsists. For some reason the use of full gain has induced noise while a slight twist of the control eliminates it. Will call Keith back next week and possibly send the XMC in to be evaluated. While the volume on the Sony is a workable, I'm sure there are others that have passive subs with outboard amps without volume controls. For the issue to be isolated to the subwoofer outputs only means there is inconsistency, because the induced noise/signal isn't present in the Front Left & Right with either amp.

May wait until after the first of he year to avoid the mass shipping season. Rather than speculate further, I'll wait until a solution is found before posting again, unless somebody has a revelation that all of us have overlooked (or given the updated info). At the end of the day this is nothing more than a toy - a very sophisticated one. That being said, I do want to take full advantage of all its capability and be able to use any amp I choose to pair with it - especially one made by the same company.

Thanks to everyone that has made suggestions. It's good to know that there is a community to offer support. And Emotiva support has served me well too, so I'm confident this will be resolved. Merry Christmas to you and yours! Chris

[socketman]

What you need to realize is there is a balance that must be struck between the output of the XMC-1 and the input gain of your amp. I would not run the amp at full gain, stay closer to 1/2 the run Dirac. Its tempting to run full gain but you will overdrive the input stage and get noise. Read this article at audioholics , since i am not an expert but have experience from my car audio days where all amps have controllable gain.

www.audioholics.com/audio-amplifier/amplifier-voltage-gain

[heroesunplugged]

Easier said than done when the majority of modern home audio amps don't have any controls.

[heroesunplugged]

I fully understand unity gain and not over-driving the equipment's input stage, but that flexibility is limited in the home audio industry to keep the end user from destroying it. Pro audio has much more flexibility and is intended to allow for a wide array of equipment to work together and usually has greater headroom to accommodate less than ideal scenarios. If the SA-250 is limited to 2 options on the gain, neither of which will work with Dirac using the XLR inputs, what is your point?

[socketman]

You said the sony has gain controls and you had it set at 100% then backed it down to 95%


Obviously the Emo amp should work well and be nicely matched for the XMC-1

[socketman]

Also has the problem with the left channel sending the amp into protect mode been eliminated. I am not trying to outsmart anyone here, just trying to help you work through possibilites bases on what you are sharing since i am not there with you. We do this at my work all the time, we discuss, suggest analyze test and try not to go down any rabbit holes along the way.

[heroesunplugged]

Sure, I get that your trying to hash this out. Everything above, points to a problem with the XMC-1 subwoofer outputs when using Dirac. Both amps are receiving additional noise from the XMC-1 that shouldn't be present. You're right, the SA-250 should be compatible with the XMC-1 and I know it is, just not when using Dirac at this point. The main channels don't induce noise when using Dirac with either amp turned to full gain, so there is a problem with the Sub outs. I've used Dirac with other subwoofers and there has never been noise present, even with the gain set around +3 dB on those subs. I have reduced the gain to take the measurements, but only to set the level to a more ideal, nominal -12 dB, that seems to work best for the sweeps within Dirac.

The Sony's volume, or gain, turned to full is no different than having a fixed gain, that can't be controlled. It's there for flexibility, like the gain switch on the SA-250. The Sony's gain is actually fine running 100% for home audio. The TA3200F may have a gain of about 26dB turned all the way up. It is lower than 29 dB because it takes more input to get the same output using the SA-250. Using it in a pro audio scenario or, using a fixed line out device, like a CD player, would be a concern at full volume. I've used the Sony with several AVRs, stereo preamps and integrated amps. Never had any noise at full gain, or been inclined to turn it down, due to being over-driven (clipping the input). I've used Audyssey and MCACC room correction with this amp and the SA-250. MCACC takes all measurements at reference level. In this scenario the noise isn't something that should even be in the signal. When setting levels for any channel within Dirac, the corresponding channels should remain silent. I've checked all of the channels for noise and it is isolated to the subwoofer outputs. No subs, no noise.

I have discovered, that I can use the lower gain setting on the SA-250, with the RCA subwoofer outputs. Noise is still present through the entire Dirac process. XLR cables are out of the question on either gain setting due to their higher output. There is a glitch on the sub outs. Whether it is software, or hardware based, is most likely going to be something Emotiva can answer - when they have the processor in front of them.