ATI AT3000 amps

[Irvrobinson]

I'm lying on my lounger now. I have my AT3005, 3002, & 6012 amps all on at the same time right now. No hum. No hiss.

Krypton's power company thanks you.

 

[ski2xblack]

Rich,

1) you may be able to bury the noise of the AV8801 by backing down the gains on the ATI. You have positively identified it as a weak link in terms of noise. But if your amp's gains are maxed, the AV8801 is not being used optimally. With the gains maxed, it takes, what, 0.7v for full output? Part of which is the audible noise you reported. I would bet that the AV8801 can push double or triple that voltage from it's pre-outs without clipping, and by doing so you increase the signal two to three times over the residual noise, thus burying it below audible levels. Try it out. Hopefully, if properly gain-staged, the AV8801's weakness can be overcome or sidestepped. (I find it difficult to believe that a top shelf component like that cannot provide top notch performance, but I could be wrong.)

2) all trannys hum to some extent, but I wouldn't expect an amp of the ATI's pedigree to be audible. (Even the quiet ones hum, but you may need a stethoscope to hear it.) Heed Irv's advice regarding your home electrical service, but keep in mind it's still possible the ATI is faulty or improperly assembled (it happens). I had a power tranny on a amp get loud, and it was purely a mechanical/mounting issue within the chassis.

As per ususal, I'm just a Dunning Kruger case with an omnimic, so corrections welcome.

Rich: This problem directly attacks the OCD centers of my mind.
Perhaps, there is a medication you can recommend

It's only legal in Colorado and Washington at this time.

 

[RichB]

Rich,

1) you may be able to bury the noise of the AV8801 by backing down the gains on the ATI. You have positively identified it as a weak link in terms of noise. But if your amp's gains are maxed, the AV8801 is not being used optimally. With the gains maxed, it takes, what, 0.7v for full output? Part of which is the audible noise you reported. I would bet that the AV8801 can push double or triple that voltage from it's pre-outs without clipping, and by doing so you increase the signal two to three times over the residual noise, thus burying it below audible levels. Try it out. Hopefully, if properly gain-staged, the AV8801's weakness can be overcome or sidestepped. (I find it difficult to believe that a top shelf component like that cannot provide top notch performance, but I could be wrong.)

I don't know how to adjust the gain on the AV8801.
You can change the volume per input but that is the same as turning up the volume.

2) all trannys hum to some extent, but I wouldn't expect an amp of the ATI's pedigree to be audible. (Even the quiet ones hum, but you may need a stethoscope to hear it.) Heed Irv's advice regarding your home electrical service, but keep in mind it's still possible the ATI is faulty or improperly assembled (it happens). I had a power tranny on a amp get loud, and it was purely a mechanical/mounting issue within the chassis.
.

Perhaps it is the nature of the beast. Apparently, my beast is a bit different.
I will discuss this with ATI on Monday.

- Rich

 

[ski2xblack]

I don't know how to adjust the gain on the AV8801.
You can change the volume per input but that is the same as turning up the volume.

I don't know specifically either, but presumably you can adjust the appropriate channels in some setup menu to compensate for the reduced sensitivity of the external amp. If the end result means turning the volume knob further to achieve the same level, you are in fact driving your output stage harder which is what you want. As long as you don't clip it. I think the manual states the pre-outs are good for +/-7v, so you can run them pretty hot (and reduce amp gain quite a bit).

 

[RichB]

While working on my "issue" , I also hooked up the RCA unbalanced connections between the Marantz.
So I decided to do some non scientific A/B comparisons.
I cannot detect any volume difference nor can I measure one using the Radio Shack meter.
I wanted to see if there were detectable differences, and I feel there were :0

I listened to the AMP connected directly to the BDP-105 and also connected via the Marantz AV8801.
In both cases, I preferred the RCA.
From the Oppo the level of detail was amazing. The XLR's did not seem to be as clean (for lack of a better term).

From the AV8801, the XLR's are a bit brighter, bringing out symbols and adding some dynamics.
But the RCA's sounds more natural. Violins have a pitch that sound correct to me.

This is not what I was expecting.
Well that was fun, I think I will hook up all the RCA's.

- Rich

 

[ski2xblack]

I listened to the AMP connected directly to the BDP-105...From the Oppo the level of detail was amazing...

Not surprising. You're feeding your amps an unattenuated (is that a word?) 2v signal from the oppo. Your AV8801 should be able to match that if we can figure out exactly what the problem is. It specs very well. Yours may be a lemon, but let's not throw it under the bus until the problem has been thoroughly assessed. In other words, HELP! More knowledgable, experienced forum members needed!

 

[RichB]

Not surprising. You're feeding your amps an unattenuated (is that a word?) 2v signal from the oppo. Your AV8801 should be able to match that if we can figure out exactly what the problem is. It specs very well. Yours may be a lemon, but let's not throw it under the bus until the problem has been thoroughly assessed. In other words, HELP! More knowledgable, experience forum members needed!

The BDP-105 was turned down

The Sabre 32-bit DAC uses the extra bits to implement the volume control so there is no loss of detail.
It is a bit clunky to use as a preamp, but it sounds great when you do.

- Rich

 

[ski2xblack]

The BDP-105 was turned down

Hmm. Then the Marantz should have had an even easier time matching it. ?? It's a head-scratcher for me. The Oppo directly to the amp must be a high benchmark for performance. I would still expect a pre-pro that retails for several thousand to hold it's own. I'm at a loss as to what's going on. Maybe the Marantz really is a lemon.

 

[RichB]

Hmm. Then the Marantz should have had an even easier time matching it. ?? It's a head-scratcher for me. The Oppo directly to the amp must be a high benchmark for performance. I would still expect a pre-pro that retails for several thousand to hold it's own. I'm at a loss as to what's going on. Maybe the Marantz really is a lemon.

The Marantz sounds very good, but it is primarily a HT preamp.
Most folks use Audyssey, I do not.
When you load up a preamp with so many craptastic features, it can take some doing to turn them off.

- Rich

 

[AcuDefTechGuy]

With nothing connected to the AT3005, it should not hum that loudly period. It pains me to say it, but I think it is a rare lemon case.

I think ATI should send FedEx/ UPS to your house to pick up the lemon AT3005 and deliver a NEW AT3005 in the process.

 

[RichB]

With nothing connected to the AT3005, it should not hum that loudly period. It pains me to say it, but I think it is a rare lemon case.

I think ATI should send FedEx/ UPS to your house to pick up the lemon AT3005 and deliver a NEW AT3005 in the process.

I have requested and RMA. The transformer hum is too much.

However, I have not given up on analyzing the problem.
My friend sent me this in an email:

I figured out how to connect this to the AC line to see the wave form. I will bring the probe and voltage divider tomorrow but you need to download the app to your iPad. It is free. The probe is what costs the money. I will also bring my Tektronics scope meter. We can also look at your speaker lines and see the hum.</SPAN>

iMSO by Oscium</SPAN>
https://itunes.apple.com/us/app/imso/id411757356?mt=8</SPAN>

We probably will not be able to determine the source of the speaker hum, but we may be able to learn something about the transformer hum.
That should be interesting.

- Rich

 

[Irvrobinson]

I have requested and RMA. The transformer hum is too much.

Unfortunate, and unusual; this is the first time I've heard of someone having a problem with an ATI amp. I can tell you that if my transformers hummed I'd send it back too.

 

[AcuDefTechGuy]

Unfortunate, and unusual; this is the first time I've heard of someone having a problem with an ATI amp. I can tell you that if my transformers hummed I'd send it back too.

Yep, any kind of noise, hum or hiss, is unacceptable with ATI amps. That's the reason we got ATI amps in the first place.

 

[AcuDefTechGuy]

I have requested and RMA.

Next question is, who is the next contestant ?

Parasound Halo? With your recent luck, better make sure about the return policy.

 

[RichB]

Next question is, who is the next contestant ?

Parasound Halo? With your recent luck, better make sure about the return policy.

I am performing some measurements of my power and the noise at my speakers.
Images to follow


- Rich

 

[RichB]

Next question is, who is the next contestant ?

Parasound Halo? With your recent luck, better make sure about the return policy.

If ATI can still work for me, I would like to stay there.
But, I do not want to keep swapping amps and waste everybody's time.

Hopefully, the measurements I sent to ATI will shed some light on the situation.

- Rich

 

[AcuDefTechGuy]

If ATI can still work for me, I would like to stay there.
But, I do not want to keep swapping amps and waste everybody's time.

Hopefully, the measurements I sent to ATI will shed some light on the situation.

- Rich

Oh, so base on the measurements, they may send you a brand new AT3005 at no additional charge?

 

[Stereojeff]

I have not seen Rich's data. The usual cause of the transformer hum Rich has reported is DC on the AC line.

The other interesting point is the lack of hum and noise when bypassing the Marantz and using the Oppo. If you follow standard trouble-shooting guidelines, that would rule out the ATI as the source of the problem.

Jeff

 

[AcuDefTechGuy]

I have not seen Rich's data. The usual cause of the transformer hum Rich has reported is DC on the AC line.

The other interesting point is the lack of hum and noise when bypassing the Marantz and using the Oppo. If you follow standard trouble-shooting guidelines, that would rule out the ATI as the source of the problem.

Jeff

So is the AT3005's transformer different than the Outlaw equivalent?

 

[RichB]

I have not seen Rich's data. The usual cause of the transformer hum Rich has reported is DC on the AC line.

The other interesting point is the lack of hum and noise when bypassing the Marantz and using the Oppo. If you follow standard trouble-shooting guidelines, that would rule out the ATI as the source of the problem.

Jeff

Actually, that is not correct.

Transformer hum is always present when there are no connections to the AMP.
Also, I just unplugged the Marantz from the wall and Transformer and speaker hum is present.

Also, check you your email, I sent you the images of our measurements.

- Rich