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#148296 - 09/26/06 07:46 PM high level and low level input simultaneously
cava Offline
enthusiast

Registered: 08/23/06
Posts: 33
I have an EP350, haven't touched it yet, which is another story. Can I connect the high level input to my receiver's front B output and the low level input to the sub pre-out at the same time? I want to do this so that when I play a two channel sacd I can still send low freq. to the sub. If I have speaker B turned off for all other sources, will that affect the sub at all? I assume the high level input does not bypass the LPF. If I were to accidentally turn on speaker B AND have output from the sub pre-out, which would the sub accept primarily? I ask this because I have roommates that probably don't know exactly what they are doing.

One last question: would using the speaker B output halve the maximum power that I could send to the front L/R speakers? In other words, what is the input impedance of the high level input on the EP350?

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#148297 - 09/27/06 03:17 AM Re: high level and low level input simultaneously [Re: cava]
JohnK Offline
shareholder in the making

Registered: 05/11/02
Posts: 10412
Cav, the first point is that it's unclear how this would have the effect with two-channel SACDs that you describe. In any case, most sub manufacturers(including Axiom for the 350)caution against making a simultaneous speaker level and line level connection. Axiom doesn't go into detail, but some others specifically warn about damage to the sub and receiver amps. Some subs apparently have totally separate input circuitry for the high and low level inputs, which prevents any interaction, and state that such a connection is okay. At a minimum, contact Axiom for further details on their circuitry before you do this.

As to your second question, sub amps typically have input impedances on the order of tens of thousands of ohms on their high level inputs and, because of this, essentially zero power is transmitted, just the signal information, and full power is still available to the other speakers. Another result of the high impedance is that although the sub and speakers are connected in parallel, there's no significant lowering of the impedance seen by the receiver. The net impedance for parallel connections is such that its reciprocal is equal to the sum of the reciprocals of the impedances of the loads. So for example, with a 32,000 ohm sub amp and an 8 0hm speaker connected in parallel the total resulting impedance is 1/32,000 + 1/8 = 1/T; 4,001/32,000= 1/T ; T=7.998 ohms.
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#148298 - 09/27/06 07:15 PM Re: high level and low level input simultaneously [Re: JohnK]
cava Offline
enthusiast

Registered: 08/23/06
Posts: 33
I have only one two channel sacd, so maybe its different than most, but I know that zero information is output from the sub pre-out. I wanted to wire it so that the sub/m22 would act like a full range speaker to the receiver. I know the low freq would still be sent to the m22's but at least they naturally roll off and then the sub could pick it up from there. I don't think my DVD player has an option to send LFE from 2 channel SACD's to the sub, so that is not an option.

I have emailed axiom about the simultaneous connections.

I know how resistors add in parallel (BSME), that's why I asked about the input impedance, but thank you.

I guess I'll just have to wait until I go home this weekend and try a few things. This week cannot go by fast enough!

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#148299 - 09/27/06 09:50 PM Re: high level and low level input simultaneously [Re: cava]
JohnK Offline
shareholder in the making

Registered: 05/11/02
Posts: 10412
Cav, it's likely that your two-channel SACD is 2.0, not 2.1, and has no separate LFE channel(the disc should contain that information). As to the low bass on the two regular channels, since the information comes in from the SACD in analog form and most receivers can't apply bass management to it, the main speakers will receive a full range signal and the sub nothing, unless your player has bass management provisions(most do)and you put them into effect. Otherwise the speaker level terminals output a full range signal and the sub out outputs nothing.
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#148300 - 09/27/06 11:47 PM Re: high level and low level input simultaneously [Re: JohnK]
pmbuko Offline
shareholder in the making

Registered: 04/02/03
Posts: 16298
Loc: Leesburg, Virginia
I had this same problem with stereo (2.0) SACDs and I got around it by using the stereo outputs on my SACD player in addition to the 5.1 outputs. This allows me to use a standard "crossover-aware" AUX input on my receiver for stereo CDs and the 5.1 input for surround SACDs.

My SACD player is also a DVD player, so I'm not sure if other players will have separate stereo outputs.
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#148301 - 09/28/06 04:58 PM Re: high level and low level input simultaneously [Re: pmbuko]
cava Offline
enthusiast

Registered: 08/23/06
Posts: 33
OK, so you're saying I could connect the front L/R outputs from the player into some other input besides the 5.1 input and then be able to apply bass management just like any other two channel source. That's a good idea, just a pain to have to move cables whenever I listen to that one CD. Why is it that so much control is lost by using the 5.1 analog input?

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#148302 - 09/28/06 05:08 PM Re: high level and low level input simultaneously [Re: cava]
dllewel Offline
connoisseur

Registered: 06/20/05
Posts: 1189
Loc: Utah, USA
The receiver would have to convert all 6 analog input channels simultaneously to digital, so that bass management can be applied. Not a feature enough users care about to warrant the cost increase to the reciever manufacturers. As John mentioned, there are some receivers that will do this- the Lexicon RV-8 I have does, and I love it. No worries or settings to change for different sources, but it certainly wasn't an inexpensive investment.

Also as John mentioned, turning on the bass management in your SACD player (setting speakers to small) should let it re-route the bass to your subwoofer channel before it leaves the player.
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M80s VP150 QS8s EP500s
ravenmanor.com/cinema/

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#148303 - 09/28/06 05:12 PM Re: high level and low level input simultaneously [Re: dllewel]
Ken.C Offline
shareholder in the making

Registered: 05/03/03
Posts: 17809
Loc: NoVA
My relatively inexpensive H/K 525 does it. But true audiophiles won't accept this theoretical degredation.
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I am the Doctor, and THIS... is my SPOON!

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#148304 - 09/28/06 05:24 PM Re: high level and low level input simultaneously [Re: Ken.C]
dllewel Offline
connoisseur

Registered: 06/20/05
Posts: 1189
Loc: Utah, USA
Quote:

My relatively inexpensive H/K 525 does it. But true audiophiles won't accept this theoretical degredation.



AFL! I guess I am not a 'true audiofile'.
_________________________
-Dave

M80s VP150 QS8s EP500s
ravenmanor.com/cinema/

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#148305 - 09/28/06 05:28 PM Re: high level and low level input simultaneously [Re: dllewel]
Ken.C Offline
shareholder in the making

Registered: 05/03/03
Posts: 17809
Loc: NoVA
<hurridly hunts around for the AFL definition post>

Likewise, not a true audiophile.
_________________________
I am the Doctor, and THIS... is my SPOON!

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