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#272625 - 09/17/09 12:55 PM Re: Axom A1400-8 amp hum from Denon AVR-4306... [Re: SolidState]
SolidState Offline
veteran

Registered: 11/08/06
Posts: 124
doh!

I have signal ground and shield mixed. Just to recap.

XLR male, hot pin 2, signal ground pin 3 and open shield to pin 1, On RCA hot pin 2 to tip and signal ground to pin 3. This is how I intend to terminate. Will this still result in the Ice module going into -10dBV mode?

Solid-State

PS I'm also curious why a module populated with only one in and out produces a hum in that channel? If you connect an in to the unused chan or in and a speaker the hum is completely gone... why?


Edited by SolidState (09/17/09 12:59 PM)

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#273065 - 09/23/09 01:28 PM Re: Axom A1400-8 amp hum from Denon AVR-4306... [Re: SolidState]
SolidState Offline
veteran

Registered: 11/08/06
Posts: 124
?

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#273137 - 09/24/09 12:06 PM Re: Axom A1400-8 amp hum from Denon AVR-4306... [Re: SolidState]
Jc Offline
aficionado

Registered: 06/27/06
Posts: 500
Loc: Sherbrooke, QC, Canada
 Originally Posted By: SolidState
?


SolidState, Axiom is not using the B&O Ice module. Axiom has evaluated it and decided to design its own digital module to overcome many shortcomings of the Ice module. Axiom not only has designed its amplifier modules in house it also manufactures it in Axiom's main Canadian facility.

To recap on the XLR pins :
Pin 2 is Hot + and Pin 3 is Hot – while Pin 1 is ground.

Hum :
The A1400 should not have hum either way. The only way this may happen is when Pin 2 is hot and Pin 3 is not connected or to a different ground than Pin 1. We do not recommend this as the A1400 has different circuitry for the unbalanced and the balanced inputs. The balanced inputs stay balanced all the way to the power stage.
_________________________
jc
Axiom Audio Expert / jc@axiomaudio.com
Recrutement d'Intégrateurs/Installateurs professionnels Québec

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#273149 - 09/24/09 01:44 PM Re: Axom A1400-8 amp hum from Denon AVR-4306... [Re: Jc]
ClubNeon Offline
connoisseur

Registered: 02/06/09
Posts: 3448
Loc: Western Maryland, USA
Just to clear up for those of us playing along at home.

What makes the A1400 pick the different circuitry when it only has one physical set of inputs?
_________________________
Pioneer VSX-1018AH-K, PDP-5020FD, DV-79AVi
Axiom M22s, VP150, QS8s
Sony PS3, surround backs
-Chris

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#273181 - 09/24/09 06:41 PM Re: Axom A1400-8 amp hum from Denon AVR-4306... [Re: ClubNeon]
Jc Offline
aficionado

Registered: 06/27/06
Posts: 500
Loc: Sherbrooke, QC, Canada
 Originally Posted By: ClubNeon
Just to clear up for those of us playing along at home.

What makes the A1400 pick the different circuitry when it only has one physical set of inputs?

Hi ClubNeon,
The input jack used by Axiom on its A1400 amplifier models is a dual type configuration. The larger central hole of the connector is for the phono type connector and the outer three identical small holes are for the XLR connector. It is like using two separate connectors. Only when an XLR connector is plugged to it that the audio signal will be processed by the balanced circuits.
_________________________
jc
Axiom Audio Expert / jc@axiomaudio.com
Recrutement d'Intégrateurs/Installateurs professionnels Québec

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#273186 - 09/24/09 07:14 PM Re: Axom A1400-8 amp hum from Denon AVR-4306... [Re: Jc]
ClubNeon Offline
connoisseur

Registered: 02/06/09
Posts: 3448
Loc: Western Maryland, USA
That was my guess.

So when using an unbalanced feed, one should always use the included adapters. They are not shorting two leads of a balanced connector together, they are in fact connecting to a different part of the input.
_________________________
Pioneer VSX-1018AH-K, PDP-5020FD, DV-79AVi
Axiom M22s, VP150, QS8s
Sony PS3, surround backs
-Chris

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#273200 - 09/25/09 10:20 AM Re: Axom A1400-8 amp hum from Denon AVR-4306... [Re: ClubNeon]
Jc Offline
aficionado

Registered: 06/27/06
Posts: 500
Loc: Sherbrooke, QC, Canada
 Originally Posted By: ClubNeon
So when using an unbalanced feed, one should always use the included adapters. They are not shorting two leads of a balanced connector together, they are in fact connecting to a different part of the input.


You are exactly right on all points !
_________________________
jc
Axiom Audio Expert / jc@axiomaudio.com
Recrutement d'Intégrateurs/Installateurs professionnels Québec

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#273767 - 09/30/09 11:08 PM Re: Axom A1400-8 amp hum from Denon AVR-4306... [Re: ClubNeon]
SolidState Offline
veteran

Registered: 11/08/06
Posts: 124
 Originally Posted By: ClubNeon
That was my guess.

So when using an unbalanced feed, one should always use the included adapters. They are not shorting two leads of a balanced connector together, they are in fact connecting to a different part of the input.


I'm not sure about that guys! If you look at the included adapters they are MONO sleeve TRS 1/4" NOT Stereo/balanced sleeve! The entire length of the ring shaft connects to the female RCA sleeve! Just by looking at the thing one can deduce that sleeve will short pin 1 and pin 3. It depends on how that hybrid XLR socket is wired though. I don't believe the pins are discrete for the TRS socket from the XLR pins on a hybrid. The jack prongs are just physically connected to the same pins for XLR balanced as TRS balanced. Please tell me the part number for the hybrid XLR and I can determine if it's a special hybrid XLR with discrete pins for the XLR and the TRS sockets. I don't believe such a beast exists though I could be wrong.

I'm very curious as to how the single ended or balanced ins are wired on the TC Preamp-3 board. I wish to understand how the TC Preamp-3 board determines if it's receiving -10dBV or +4dBu AND singled ended or differential signals as they are NOT the same thing! Signal symmetry as in single ended or differential is DIFFERENT and INDEPENDENT from "balanced" as it pertains to interconnect pinout/pre circuit! I have tried open and closed shield on pin 1 XLR A1400 on the RCA sleeve. I found that open shield as in pin 1 XLR in is tied to Mogami 2549 shielding but open at the RCA end with RCA hot tip to XLR pin 2 and RCA single ended sleeve return to XLR pin 3 produced WORSE hum! than XLR pin 1 and 3 shorting at sleeve! I'm am starting to think that pin 1 on the XLR in on the A1400 is tied to signal ground and NOT chassis ground when TC Preamp-3 board is in -10 single ended mode!

Please axioms don't fluff this off! I know you installed a new grounding bar in later revisions of this piece! Is not pin 1 on that hybrid XLR pined to this ground bar! I sure hope it's not pined to signal ground! It seems to be guys when the TC Preamp-3 board is in -10 singled ended mode! All I need for a hum free singled ended source to work from RCA to XLR is the TC Preamp-3 board to go into -10 singled ended mode and for the hybrid XLR pinout to be pin 1 chassis ground (NOT SIGNAL GROUND!) pin 2 singled end hot and pin 3 return. If I then used a two conductor with shield cable like my Mogami 2549 and pinout the XLR pin 1 shield pin 2 + pin 3 - and at the RCA end pin 2 to tip and pin 3 sleave with the ground shielding OPEN it should work best. I think the problem is that pin 1 is signal ground and NOT chassis ground when TC Preamp-3 board is in -10 singled ended mode. Considering the unit is a true differential designed as Jc sorta alluded to I'd assume that the XLR in terms of the TC Preamp-3 +4 differential mode is pinned out as XLR pin 1 chassis ground, pin 2 "+" pin 3 "-" as in a true differential circuit with same impedance in both directions. Again it's important to note "quazi balacing" with balums, VERY common because 90% of amps with balanced ins are NOT true differential designs, has led to the practice of pinning signal ground to XLR pin 1 because in a non differential design chassis is signal ground right!

Please read these article from rane

Sound System Interconnection

Grounding and Shielding Audio Devices

Solid-State

PS If you really wanna take the red pill check out this article from Rane on the Linkwitz-Riley crossover
Linkwitz-Riley Crossover Brilliance
It really nailed it in my head for me this week working on my own speakers!



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#273769 - 09/30/09 11:29 PM Re: Axom A1400-8 amp hum from Denon AVR-4306... [Re: Jc]
SolidState Offline
veteran

Registered: 11/08/06
Posts: 124
The XLR/TRS combo jack has discrete pins for XLR and TRS? If that is the case then nothing is connected to sleeve on the TRS? Why have some reported better results with a XLR to RCA cable two conductor not coaxial?

Solid-State


Edited by SolidState (10/01/09 12:00 AM)

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#273771 - 10/01/09 12:05 AM Re: Axom A1400-8 amp hum from Denon AVR-4306... [Re: SolidState]
SolidState Offline
veteran

Registered: 11/08/06
Posts: 124
OK I'm wrong. I have it now in a catalog. On the back of the XLR/TRS combo jack is six solder points. Pins 1, 2 and 3 as well as tip, ring and sleeve as well as XLR jack ground. The included mono TRS adapters would still jump ring and sleeve though it sounds like nothing is soldered to the sleeve pad.

Solid-State

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