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How to do high level input right with a sub.

Dennis_FL

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I have the KEF LS50 metas and a KEF KC62 sub. I have noted the preference by some for high level sub input for the best performance - especially in music.

I use a good DAC for the source and only play 2 channel music from Roon or JRiver. My Marantz is 11 channel Atmos capable and is definately overkill and I use it only as a preamp as I have an Emotiva external 200 watt amp for the mains

I'm thinking of trying the high level input (currently I use the low level input and do Audyssey room correction) just to see if I agree with the REL high level crowd.

Not sure how to do the speaker setup in the Marantz. I'm thinking I put the speaker setup as 2 large and no sub. Then to get volume right on the sub, I presume if I measure white noise dBa from the Mains with the sub off and then adjust the sub level to the same value with the main speakers off ?? There is no crossover in this case. The KEF sub has speaker wire input but no output like REL subs.

Then playback with the Marantz using Pure Direct???

Another alternative is to bypass the receiver entirely and wire the DAC directly to the amp (both have XLR balanced connectors) and do eq room correction in Roon.

.....seeking advice !!!! Am I on the right track?
 

KMO

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It sounds to me like you're chasing infinitesimal (and super debatable) "audiophile" type benefits, while not doing the one thing you can easily do with the kit available.

Which is to set the speakers to SMALL, set the receiver crossover to something like 80Hz, set sub to "LFE" (ie no filter), and let the receiver do its usual crossover function, in non-DIRECT mode.

I do not believe there's any possible gain from any other configuration without crossover that would offer superior results to a properly-crossed sub. Unlike many, you have something already there that can do digital DSP crossover. You should use it!

(With regard to this "REL high-level crowd" - I actually can't see any reason why high-level inputs would be "better" than low-level. Or vice versa, except that the low-level is the route permitting crossover. But if not doing crossover, they should be equivalent. Conceivably some particular sub might have an implementation where one is better, but there shouldn't be a difference in principle.)
 

raindance

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Audyssey has much higher resolution filters in the subwoofer channel. Connecting via high level would simply be silly.

Maybe the audiophools like a whole lot of overlap at the crossover point?
 
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Dennis_FL

Dennis_FL

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Which is to set the speakers to SMALL, set the receiver crossover to something like 80Hz, set sub to "LFE" (ie no filter), and let the receiver do its usual crossover function, in non-DIRECT mode

Yeah...that's what I do now. And actually that's what I'm comparing to. I don't think I made it clear above that I'm doing a test. I think the argument for high level is explained by REL fairly well here (REL You Tube video).

And I had read elsewhere on this forum that there is audio degradation when the AVR takes the analog signal from the DAC and does a analog to digital conversion and does it's equalization and crossovers and converts back with DACs and ADCs not as good as the source DAC.

Resampling a Hi Res source just doesn't sit right. But if my ears can't tell - then at least I know.

The best place to do the room equalization and digital volume level control is upstream of the DAC. I have the capabilities to do this but it a royal pain in the butt and I'd rather not. It does have one extra benefit, however. I can sell my AVR and the rack as I just need the DAC and amp and free up some floor space.
 

raindance

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You're going to compare apples to oranges and make a judgement? Obviously it'll sound different.

The good that room correction does far outweighs any degradation from the ADC/DAC inaccuracies.
 

KMO

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And I had read elsewhere on this forum that there is audio degradation when the AVR takes the analog signal from the DAC and does a analog to digital conversion and does it's equalization and crossovers and converts back with DACs and ADCs not as good as the source DAC.

Resampling a Hi Res source just doesn't sit right. But if my ears can't tell - then at least I know.
Yes, that D->A->D cycle is pointless. (In principle - maybe it might make sense as a bug workaround in some weird scenario).

You would do better to feed the digital signal straight to the receiver, and bypass the DAC, if you're running non-DIRECT.

Anyway, for test purposes, just set the Marantz to DIRECT, with the direct-specific "Subwoofer" setting in "Surround parameters" set to off. You can leave the main speaker-config as-is, which will ease switching back and forwards between the two.

For level, how did you level-calibrate with non-DIRECT? Left it to Audyssey? For comparison, you probably want to get the bass level matched to that. Get readings of various test signals with your current stuff, and try to match it.
 
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Dennis_FL

Dennis_FL

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Yes, that D->A->D cycle is pointless. (In principle - maybe it might make sense as a bug workaround in some weird scenario).

You would do better to feed the digital signal straight to the receiver, and bypass the DAC, if you're running non-DIRECT.

Anyway, for test purposes, just set the Marantz to DIRECT, with the direct-specific "Subwoofer" setting in "Surround parameters" set to off. You can leave the main speaker-config as-is, which will ease switching back and forwards between the two.

For level, how did you level-calibrate with non-DIRECT? Left it to Audyssey? For comparison, you probably want to get the bass level matched to that. Get readings of various test signals with your current stuff, and try to match it.
Yes...I used Audyssey and the Marantz mike for non-DIRECT. (I also have a Radio Shack dB meter available and I have a miniDSP USB mike for room corrections using Roon and I can use them for Direct level measurements).

I can't easily bypass the DAC with non-DIRECT. I don't have USB input on the receiver and I don't have digital out on my iMac (older Macs had TosLink) so I'd need a converter.

I do have the capability of bypassing the DAC via HDMI from a Raspberry Pi or via Streaming/Air Play. Not sure what the res on HDMI is. I know Air Play is downgraded quite a bit.
 
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KMO

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I can't easily bypass the DAC with non-DIRECT. I don't have USB input on the receiver and I don't have digital out on my iMac (older Macs had TosLink) so I'd need a converter.

In that case, I wouldn't sweat it. The D->A->D cycle may be inevitable with the kit you have, in that scenario, and in that case, having the first D->A step be as good as possible is a good thing. The DAC isn't being "wasted", I guess. It's acting as part of the converter to get your USB into the receiver's DSP.

HDMI, ever since 1.0, can do at least [email protected]@24-bit. Receiver should support that, but don't know about what your individual other bits do.

Although note that the receiver's processing may downsample. Audyssey is likely to quietly downsample to 48kHz or 96kHz. Bass management probably runs at the full 192kHz.
 

KMO

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I think the argument for high level is explained by REL fairly well here (REL You Tube video).
It's not a very good argument. Yes, if your power amplifier has some particular sound signature, then yes, bypassing it with line-level sub input will lose that sound signature in the subwoofer frequencies.

But if your power amplifier is any good, it will be flat and undistorted, like the amplifier in the subwoofer is assumed to be. There really shouldn't be any distortions or non-linear responses to "preserve". (And even if there was some desired signature, it would not be in the subwoofer range - that's going to be dominated by room response).

Oh, and on top of that, the benefit of crossed-over line-level stuff is to take load off the power amplifier and speakers. Both will be doing a fraction of the work if the mains are high-pass filtered, and that should significantly increase their remaining performance in the remaining signal. They'll be running far less close to power, heat and excursion limits. You lose all of that if using high-level inputs. You're "preserving" the heavily-loaded attempting-to-do-all-the-bass state of the mains. But that's not a good thing.

Sorry, that video's just reassured me that KEF was a better choice of supplier. Never seen them produce anything quite like that.

Actually, that's not true. There was this:

 
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Dennis_FL

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Oh that's funny.

There are others in favor of high level input. This guy I have trouble staying focused with him so I skipped through it but he also likes high level. And this guy is all in favor of the high level with KEFs

What got me started was I sold my old REL speaker on Craigslist last week and the guy calls me yesterday asking if I still had the high level input cable.
 

KMO

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Jay doesn't say why he's using the high-level, just that he is. That PS Audio guy repeats the "sound signature" argument. "The job of the subwoofer is to disappear" - so it has to blend in with the amplifier's signature. Except, of course, the job of the amplifier is also to disappear. Arguably, if the amplifier's failing to disappear, taking it out of the circuit for low frequencies is possibly a good thing. Give it less chance to mess with the audio.

It's interesting. I'm getting the impression that REL, and maybe others, are trying to plug the high-level as "better" because they have it as a feature that many others don't.

No, I don't buy it at all. They are a convenience feature for 2-channel users - they're a mechanism that can always work - as you always have speaker connections, but might not have pre outs.

But because most stuff has pre outs now, the high-level inputs are getting less of a standard feature in subs, which is somehow making them "premium".

No, no, no.

The crossover is real and important, and multiple orders of magnitude more significant than any possible "power amplifier signature" that might be preserved by the high level.

But I guess if you had no opportunity of crossover, so you were going to be running speakers full-range either way, then sure, why not use high-level?
 
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MattHooper

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I initially tried the high level connections for my JL Audio subwoofers just to check out the "REL method."

I had much better success and an easier time integrating the speakers using a crossover and splitting the signal to mains and sub.

I actually found just running the speakers full range and adding a sub changed the tone in a way I didn't like (darkened, rolled off). Using the crossover, especially with the JL Audio CR 1 crossover, I got much closer to the sound I liked.
 
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Dennis_FL

Dennis_FL

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I initially tried the high level connections for my JL Audio subwoofers just to check out the "REL method."

I had much better success and an easier time integrating the speakers using a crossover and splitting the signal to mains and sub.

I actually found just running the speakers full range and adding a sub changed the tone in a way I didn't like (darkened, rolled off). Using the crossover, especially with the JL Audio CR 1 crossover, I got much closer to the sound I liked.
When you wired with high level….how did you setup your receiver?
 

donald24

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I think, like already stated, it depends on your setup. I had no option than to integrate my sub with an SMSL-DA-8 on high level, so I took that route. It sounded great, once dialed in the cut-off frequency on the sub and played around with the phase-shift of it.
The successor of the DA8, which I am now using, now has a dedicated pre-out, but I am not feeling the need to change a working setup. In the end, all that counts, is your personal satisfaction of what you are hearing. But you must try, try and try..... to get to it - otherwise you end up in doubt. Playing around is a good thing!
 

MattHooper

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When you wired with high level….how did you setup your receiver?

I wasn't using an AV reciever. Just running a standard 2 channel set up. Preamp/amp/speakers. I ran a wire from my speaker terminals to the high level in put on the sub.
 

newjohnre

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I have the KEF LS50 metas and a KEF KC62 sub. I have noted the preference by some for high level sub input for the best performance - especially in music.

I use a good DAC for the source and only play 2 channel music from Roon or JRiver. My Marantz is 11 channel Atmos capable and is definately overkill and I use it only as a preamp as I have an Emotiva external 200 watt amp for the mains

I'm thinking of trying the high level input (currently I use the low level input and do Audyssey room correction) just to see if I agree with the REL high level crowd.

Not sure how to do the speaker setup in the Marantz. I'm thinking I put the speaker setup as 2 large and no sub. Then to get volume right on the sub, I presume if I measure white noise dBa from the Mains with the sub off and then adjust the sub level to the same value with the main speakers off ?? There is no crossover in this case. The KEF sub has speaker wire input but no output like REL subs.

Then playback with the Marantz using Pure Direct???

Another alternative is to bypass the receiver entirely and wire the DAC directly to the amp (both have XLR balanced connectors) and do eq room correction in Roon.

.....seeking advice !!!! Am I on the right track?
Revisiting this because I am in a similar situation. I have KEF LS50 Metas, with two SVS SB1000 subwoofers and an older Velodyne sub that I am mixing in with a MiniDSP 2x4 HD, a Marantz 8802A preamp and a Chord Qutest DAC.

It may be psychological but I prefer the Chord Qutest DAC over the Marantz internal DAC and it sounds best in Pure Direct Mode, bypassing any EQ and eliminating the D to A to D to A cycle. I am considering trying out high level connections to blend the subs, aligning timing and phase manually. Normally I wouldn't consider this, but the KEF LS50's lack of bass allows for a more natural transition (similar to the Earl Geddes method). I'm curious if you ever got around to trying this and what you found.
 
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Dennis_FL

Dennis_FL

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Revisiting this because I am in a similar situation. I have KEF LS50 Metas, with two SVS SB1000 subwoofers and an older Velodyne sub that I am mixing in with a MiniDSP 2x4 HD, a Marantz 8802A preamp and a Chord Qutest DAC.

It may be psychological but I prefer the Chord Qutest DAC over the Marantz internal DAC and it sounds best in Pure Direct Mode, bypassing any EQ and eliminating the D to A to D to A cycle. I am considering trying out high level connections to blend the subs, aligning timing and phase manually. Normally I wouldn't consider this, but the KEF LS50's lack of bass allows for a more natural transition (similar to the Earl Geddes method). I'm curious if you ever got around to trying this and what you found.
I tried it both ways and when I used the Marantz, there was just something missing (even with Pure Direct). Especially with musical instruments. I was successful in using the 4V XLR output of my DAC directly to the amp and it worked great.

So my Marantz is on ebay as we speak type. I also ordered a Buckeye amp and when it arrives, I'll sell my 67 pound AB amp as well.

I checked the frequency response using a calibrated USB mike and REW and it was really flat at the level I usually listen (68 dB) but at 75 dB it had some room acoustic dips and peaks I need to correct. I have the KEF sub at high level in parallel with the KEF speakers and I get really good sound. I turned the volume knob on the sub until it had the same dB as the L/R speakers using a sub setup CD I found on Tidal.
 

newjohnre

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I tried it both ways and when I used the Marantz, there was just something missing (even with Pure Direct). Especially with musical instruments. I was successful in using the 4V XLR output of my DAC directly to the amp and it worked great.

So my Marantz is on ebay as we speak type. I also ordered a Buckeye amp and when it arrives, I'll sell my 67 pound AB amp as well.

I checked the frequency response using a calibrated USB mike and REW and it was really flat at the level I usually listen (68 dB) but at 75 dB it had some room acoustic dips and peaks I need to correct. I have the KEF sub at high level in parallel with the KEF speakers and I get really good sound. I turned the volume knob on the sub until it had the same dB as the L/R speakers using a sub setup CD I found on Tidal.
That is extremely helpful, much appreciated!

It sounds like we are very similar in what we like about what we hear and our equipment is close enough that I think we are on the same page independently which is significant in my opinion. I intentionally chose the LS50 over other speakers because I knew that I wanted maximum flexibility of driver location...which obviously means at least subwoofer is needed. But somewhere along the line there is just too much sample rate conversion and DSP that is effecting the clarity. The MiniDSP 2x4 HD and Marantz 8802A both have very good DACs in general so I don't think it is a matter of quality, but I haven't tried just using the standard dual subwoofer outputs from the Marantz with this setup and dropping down to 2 subs so that might be an alternative before trying high-level connections and Pure Mode (or Large Mains settings depending on mode).

Wanting to keep this as part of my home theater I think I will have to go through the Marantz in Pure Mode anyway, plus I wouldn't feel comfortable using the laptop as a volume control into my amplifier. I suppose that would remove as many things as possible from the chain though an I like the simplicity of that
 
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newjohnre

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I tried it both ways and when I used the Marantz, there was just something missing (even with Pure Direct). Especially with musical instruments. I was successful in using the 4V XLR output of my DAC directly to the amp and it worked great.

So my Marantz is on ebay as we speak type. I also ordered a Buckeye amp and when it arrives, I'll sell my 67 pound AB amp as well.

I checked the frequency response using a calibrated USB mike and REW and it was really flat at the level I usually listen (68 dB) but at 75 dB it had some room acoustic dips and peaks I need to correct. I have the KEF sub at high level in parallel with the KEF speakers and I get really good sound. I turned the volume knob on the sub until it had the same dB as the L/R speakers using a sub setup CD I found on Tidal.
Well, I'm kinda surprised but I found a better way to do all this and achieve bass management without having to go through the DAC in the my Marantz 8802A. This allows me to use the subwoofers with my LS50 Metas and my outboard DAC without double-bass issues. Long story short, on Denon and Marantz preamps you can turn on the normally shunned setting LFE+Main and it will send an equal signal to the mains and subs at all time, even in Pure Direct Mode. To do this correctly you could use whatever bass optimization you choose but the outboard DAC is treated as analog passthrough with no filtering.

This was most important to me in regards to multi-channel SACD that really wants full range in all speakers, especially for high dynamic range stuff like 1812.

Here's what gave the insight:

 

KMO

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One thing that thread seemed to miss in all the ranting from those not wanting the behaviour is that the behaviour is optional.

There's a "Subwoofer" setting in "Surround Parameters" that controls subwoofer output for Stereo and Direct modes when LFE+Main is engaged.

The "Subwoofer" setting is on by default, so the behaviour happens if you select LFE+Main (which is not on by default), unless you find that setting and turn it off. I believe it's only visible when actually in that mode, like other Surround Parameters that only appear when relevant.

And at least on some models, it actually is a fixed-frequency analogue 80Hz LPF, not going through the DSP, at least if using a direct analogue source.

(I'm talking from Denon experience here - I expect Marantzes are similar).
 
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