Advice on AVR in conjunction with Concentra II and MG1.6

[jbaumann]

Hi all,

I have a Jeff Rowland ConcentraII and Magnepan MG1.6 loudspeakers, and apart from that a home theater system (5.1).

Since my space is limited I would like to somehow join these two. For this I would like to connect a Pre-amp out of the main speakers from an AVR to the ConcentraII and connect the other speakers to the AVR.

To use the system for other things than movies, I could either use the DACs of the AVR if its quality is good enough, or buy something like a Topping E70 and connect it to a Raspberry for network connectivity to have a high-quality DAC instead of the internal ones of the AVR. The different reviews suggest that using an external DAC would be better in most cases. Is this correct?

Is it important that the AVR is able to disconnect its amp stage when I use the pre-amp out (it seems the the Denons starting with the X6700H are able to do that)? Or is that something that can be ignored since the amp stage is driving nothing?

If the AVR is good enough, should I consider removing the ConcentraII from the equation i.e., connect the MG1.6 directly to the AVR?

And should I consider Dirac (since the room topology is not ideal)?

What would be the best way to go, and what would be the best AVR to choose?

Thanks in advance for any suggestions, tips and comments (even if it is something like „this is the most stupid idea I‘ve ever heard“).

Cheers, Joe

 

[polmuaddib]

Hi! Welcome to ASR.

What you are trying to do is to use your amp section of ConcentraII for front speakers and have two systems joined on the same speakers.
The feature you would need on your integrated amp is called Home Theater Bypass and it bypasses the preamp section of integrated when you are using AVR and you get more powerful amplification. You connect the preamp of AVR to a designated surround (bypass) input on the integrated and then you control the volume of that source on the AVR.

The problem is that your Concentra II does not have that feature as far as I can tell. I can't find the manual onilne, so if you have it, you can send it to me and I would check, but it is not likely.
There is a way that you can still do this, but you would need to find out what is the volume level of your Concentra II when the gain reaches Unity gain. In my case, I have a JRDG Capri preamp, when the volume control is set to 85.5, the preamplifier is set for unity (0 dB) gain from any input to any output. So, basically you set the volume to 85.5 on JRDG and you should get HT bypass, because there is no attenuation or amplification to the source signal. But, I don't know if 85.5 is the volume level for your integrated... It might be different, and it should be possible to measure on good ADC device, but...

As for the benefits of this approach, that is debatable. For one thing you would surely get more powerful amplification for your speakers when using Concentra II, rather then AVR's internal amps. Now, depending on your speakers, room size, listening levels, I can't say for sure do you need this or don't.

I use this approach and my main benefit is that I have a simple stereo setup when I want to listen to 2 channel music, rather then listening stereo on AVR. Sure, I can just use Pure direct feature on an AVR and basically get the same result, but I enjoy the look and feel of my JRDG stereo setup.

DAC in your AVR is probably good enough. Sure, any Topping DAC has better SINAD and is likely a better performer in all aspects, but wheteher that is audibly better, that is another thing. Probably not, and even if you could tell them apart in a well setup double blind test, the difference would likely be small.
However, If you compare them by ear and know which DAC you are listening, who knows what differences you would hear.

Finally, is all that worth it? IMHO you might enjoy the benefits of more powerful amplification, but that's it. You could get that with much cheaper power amp and the setup would be simpler. Just get an amp with trigger input (if your AVR has 12V trigger jacks) so that the amp turns on with AVR.

Cheers!

 

[jbaumann]

Hi polmuaddib,

Thank you for your answer.

The ConcentraII doesn‘t allow to bypass the preamps, which means I will have to set the volume to unity gain. I will probably get the exact setting from the manufacturer.

My idea is to use the whole system the same way you do it, by listening to stereo using the Concentra and the Topping instead of using the AVR, and using the AVR for home theater etc.

The MG1.6 are magnetostatic speakers which need quite some amp power to sound as incredible as they can. And I know that the Concentra has the oomph to do that. I have also considered replacing it with power amps, but it is not easy to part with it.

But all in all you would suggest that an extra DAC is not necessary, if not for my listening preferences. This is something I will have to think about.

The next question is, which AVR would be suitable for this use case?

Cheers, Joe
[And I just now realized the origin of your name]

 

[polmuaddib]

Then, of course, keep the Concentra. It's a beautiful amp with enough power.

As for the DAC, you would not get any benefit in sound quality from buying a separate DAC, but if you want to keep separate ways of audio between AVR and Concentra, then you need a separate DAC. Get some cheap Topping or SMSL or whatever DAC is tested here. Thankfully, there are plenty. My advice is to get the cheapest one that measures ok with balanced outputs, just in case.

As for AVR, that really depends on many things. How many speakers you plan, do you need 8k signal, room correction, do you need balanced outputs (which you might need when making a complex system because ground loops can appear) and so on.
Also, ASR is a good place to start looking, because there are many reviews.

Bye

 

[jbaumann]

I selected the DAC (Topping E70) because it is the cheapest one that provides balanced output and a power supply of its own (meaning I don‘t have to search for a good power supply).

Regarding the AVR: I currently have a 5.1 system, and while I would say I don‘t need more, I would like to have some more channels just in case. I would definitely go for 8K though. I think room correction is also very sensible (which is why in my first post I asked about Dirac). I haven‘t thought about balanced outputs (I assume pre-amp), does any AVR offer that at least for the two main speakers?

I have read through many of the reviews, and to me it seems that a Denon AVR would be the best choice, either a 3800H (if I decide to use active speakers in the future), or a 4800H o 6700H for passive speakers. Since the last two have nearly the same price, is there a notable difference apart from the number of channels?

Are there other manufacturers with products that could compete?

Thanks for all the help, Joe

 

[polmuaddib]

As for Denon, I would rather go with newer models because they have all 8K inputs and support Dirac, or rather will after update. I am not sure, really. You have to research that for details. I don't see any advantage in going with 6700 model. Only slightly more powerful amps, which makes no difference and maybe the build quality. IMHO 3800 makes the most sense for you and is a simpler way.

What looks interesting to me is Integra DRX 8.4 av reciever. It has three balanced outputs for three front channels, two XLRs for subs and two XLRs for input. It's likely more expensive then Denon.

Keep in mind that when you add more complexity to your system, meaning more components, unbalanced connections are risky. You can easily develop ground loop which can be hard to track and almost impossible to remove. So, if you plan to use active speakers in future, remember that they all have amps which have grounded connections.
So, another option is, of course more expensive, AV Processor with XLR outputs and separate amps. In the beginning, you get an AVP and some cheaper d class multichannel balanced amp for three more channels.

 

[jbaumann]

The Integra DRX 8.4 looks like a dream come true. But the price is very steep, and with the amplifier I would have to remove the Concentra, because that amplifier looks like it is able to directly drive the Magnepan speakers without problems.

So this means I have to decide between keeping the Concentra and buying an X3800H, or trying to sell the Concentra and buying the DRX8.4 as soon as possible (it seems May/June).

Btw., what about Marantz, Pioneer or Onkyo amplifiers? I got the impression that they don‘t provide the same „bang for the buck“ as the Denon‘s. Is that true?

Cheers, Joe

 

[polmuaddib]

Well, of AVRs reviewed here, Denon models tend to measure better then Marantz, Pioneer and Onkyo.
They have enough features, the price is right, looks are ok... Yeah, I'd say Denon is a good option.
I own AVR 4500H, so...

 

[jbaumann]

Thanks to your advice, I have now ordered the X3800H (a special offer, 1199€ in Germany).

The remaining question is, can I connect the pre-amp out of the X3800H to the line-in of the Concentra without problems? I‘ve been trying to find out the respective maximum voltage levels without any clear answer. It seems that line-out is normally between 100mV and 2V RMS, with XLR connections doubling this to 4V. Pre-Amp is even less clear, but a lot of references seem to see no problem in connecting pre-amp out to line-in…

 

[polmuaddib]

You can connect front L/R preouts from Denon to some RCA input of the Concentra, but the problem will be that your volume control on Concentra will still be active. So, you don't know the correct volume level on Concentra that matches the center and surrounds.
There are two ways around this problem.
One is simpler and you just make an aproximate volume level on concentra with speaker level matching on Denon, write that volume level down and then calibrate Denon and you will get a nice result. Then, when you switch to that input, call it surround input, you always make the same volume level.
BTW, Audyssey app is a must. You buy that.

The other way is to measure concentra and find out the volume level for unity gain on input.

And the third way is to just write to JRDG and ask for volume level on Concentra for unity gain. They will surely respond.

 

[LTig]

You can connect front L/R preouts from Denon to some RCA input of the Concentra, but the problem will be that your volume control on Concentra will still be active. So, you don't know the correct volume level on Concentra that matches the center and surrounds.
There are two ways around this problem.
One is simpler and you just make an aproximate volume level on concentra with speaker level matching on Denon, write that volume level down and then calibrate Denon and you will get a nice result. Then, when you switch to that input, call it surround input, you always make the same volume level.
BTW, Audyssey app is a must. You buy that.

The other way is to measure concentra and find out the volume level for unity gain on input.

And the third way is to just write to JRDG and ask for volume level on Concentra for unity gain. They will surely respond.

This. Don't make it more complex than necessary.

 

[jbaumann]

I have asked JRDG and they gave me an answer (unity gain is 84). This sounds pretty high to me, but they know best

And I already have ordered a UMIK-1 microphone to play around with the room acoustics, but the Audyssey app seems very interesting, so I will get that too. Thanks for that pointer, I didn‘t know that they have such an app.

And only to be absolutely sure: The maximum voltage levels of a pre amp out are the same as a line-out?

 

[polmuaddib]

And only to be absolutely sure: The maximum voltage levels of a pre amp out are the same as a line-out?

I don't know what you mean by that. If you are asking if preamp out and line out are the same thing, they are not. Preamp out has variable voltage controlled by volume control of the output device and line out is fixed voltage where the volume is controlled by the recieving device.
But you should not care about this in your case.
You are connecting front preouts from Denon AVR to one of your inputs, say input 1, on Concentra. Your front speakers are connected to Concentra. If you have a cd player, you connect it to input 2 on Concentra. Then, when you listen to cd, you choose input 2 on Concentra and you change the volume on Concentra. And when you want to listen to HT, specifically, Denon AVR, you select input 1 on Concentra and set the volume to 84 and then you change the voume on Denon AVR and not on Concentra anymore. Basically, Concentra becomes a poweramp in this combination and you forget about it's volume control.

Also, don't worry if it's 84. It is supposed to be high, because it's 0 dB - No attenuation, full power signal, but not amplified either.

 

[jbaumann]

An update: I have now received my Denon X38000H, have connected everything and have programmed my home automation so that the amplifiers are turned on and off depending on whether I want to hear stereo or watch a movie (e.g., using Tasmota to set the volume of the Concentra via IR, switching the input channels etc.).
I‘m using a E70 DAC connected to PiCorePlayer to listen to FLAC music (and I will have to test whether I’m able to hear a difference to AAC).
I set the volume to a fixed 84 on my Concentra (as discussed above), Since I cannot hear any noise without input, even if my ear is directly at the speaker, I think shielding is good enough.
I still have to solve some problems with the room acoustics. I had a first measurement run with Audyssey and hoped to be able to read the data afterwards with the app (which I bought thanks to your advice). No such luck. So I will have to run the tests again. In addition I bought a UMIK-1 and measured the room with REW.
The results are not that encouraging, but I have to live with the room. I changed the fronts of one of the cabinets (from glass to wood) to get rid of some of the harmonic distortions, but I still have some massive dampening in the area of 30, 70 and 200 Hz even after moving the listening position.
I just ordered an SB1000Pro to help me with that, and I hope it is fast enough to keep up with the Maggies (since electrostatic speakers are extremely fast).

Do you have any advice on treating the room while keeping it „normal“ i.e., keeping the WAF high?

 

[polmuaddib]

I had a first measurement run with Audyssey and hoped to be able to read the data afterwards with the app

There is a good review post about Audyssey by Amir. You can read that and go research further.
As for treating the room, I have no experience. I have some mini bass traps that I hid in the corner behind the library shelf (there is about 30 cm space between the corner of the room and the shelf). I put three of those and they are rotated the way they can't be easily seen. At least my wife hasn't freeked out about them, so good enough.
Those mini bass traps gave me some minor improvement in filling a bass dip at around 80hz... couple of dBs. Audible? I am not sure...
I kept them, but I have not measrued in a while.

Sonitus is the brand.

 

[peng]

The results are not that encouraging, but I have to live with the room. I changed the fronts of one of the cabinets (from glass to wood) to get rid of some of the harmonic distortions, but I still have some massive dampening in the area of 30, 70 and 200 Hz even after moving the listening position.
I just ordered an SB1000Pro to help me with that, and I hope it is fast enough to keep up with the Maggies (since electrostatic speakers are extremely fast).

Do you have any advice on treating the room while keeping it „normal“ i.e., keeping the WAF high?

With the app, just the $20 one you should be able to get decent result. Below is an example of mine with no manual adjustment vs with some manual tweaks, just ran it with the app:

The red curve is the one without any manual tweaks, just ran it with the app and the results were already very acceptable. The blue one is the much improved one after some tweaks. Different room will get different results but I am sure you can get at least +/- 5 dB peak to peak in the 20-200 Hz range.

I did not use any room treatment, just rugs and furniture.

 

[peng]

Thanks to your advice, I have now ordered the X3800H (a special offer, 1199€ in Germany).

The remaining question is, can I connect the pre-amp out of the X3800H to the line-in of the Concentra without problems? I‘ve been trying to find out the respective maximum voltage levels without any clear answer. It seems that line-out is normally between 100mV and 2V RMS, with XLR connections doubling this to 4V. Pre-Amp is even less clear, but a lot of references seem to see no problem in connecting pre-amp out to line-in…

Pre out will vary with the input level, and the volume setting. Line out will be independent of the volume, but vary with the input level. Neither one has a "fixed" voltage, obviously, unless you play a constant level tone such as a 1000 Hz sine wave. The minimum output voltage would naturally be 0 V, not 100 mV whether it is the pre out or line out.

Based on recent measurements of various Denon and Marantz AVRs, you can expect the Denon AVR-X3800H pre out to reach as high as 4 V to 4.5 V at near clipping. That's high enough to drive just about any power amps to their rated output, definitely no problem driving your Concentra II amp that is rated just 150 W iirc.

Using the JR amp's volume control with the Denon AVR is unnecessary and there is no benefits in doing so. I doubt you can hear the difference either way, but in theory, you will get more distortions and noise if the signal has to go through two preamp's circuitry. If the integrated amp does not have the bypass feature, it is best to keep them separate. For quick switching between the two systems, you can get an amp selector switch for under $100.

Something like this may work for you:

https://www.amazon.com/Amplifier-Receiver-Speakers-Selector-Switcher/dp/B0796KGVXT/ref=sr_1_4?keywords=amplifier+selector+switch&qid=1683052100&sr=8-4

 

[jbaumann]

After having played around with my system for quite some time I have now reached a state that is good enough for me (at least for the time being).

To recap:
For stereo listening I have an RPi4 running Moode with a Topping E70 DAC as transport, this is connected via XLR to my Concentra and via RCA cable to the SB1000Pro subwoofer. The Concentra drives the two MG1.6 (with a fixed volume of 84 as suggested by JR). Volume regulation is done in CamillaDSP in the RPi4, the E70 is set to DAC mode (no preamp functionality).

In a first step I used the equalizer DSP in the SB1000Pro to match the loudspeakers and the sub woofer as good as possible. In the second step I configured CamillaDSP (a very performant and technically excellent software DSP that can be run under Moode) to correct the frequencies that were too loud. Now between 65-400Hz there are still a lot of ups and downs, but nothing major and all less the 6dB.

For all of that I used REW to measure the frequency response. I also used the EQ computation for filters, but had to adjust them manually afterwards, because the room/reality got into the way of the computations. This took quite a long time, changing filters, measuring, changing again, rinse and repeat...

Remaining problem: The room geometry introduces some "holes", the biggest one at 27Hz (more than 20dB). But for my ears it works good enough that I don't invest even more time into configuring CamillaDSP in the RPi any further (even though it has more than enough reserves to add around 50-100 additional filters...).

If there's a way to do room treatment without destroying the livability (i.e., the WAF) then I would be interested to try that. But to my old ears the sound is already pretty good and very enjoyable, so I'm very happy with that part.

For movies I had bought the Denon X3800H, and the app that can be used to configure Audyssey (as you guys suggested, thank you). The effect speakers are connected to the Denon, the front left and front right amps are turned off and the preamp out is connected to the Concentra. This means that for movies the stereo system is integrated into the movie system

Using the app it was very simple to do the measurements and configure Audyssey. I'm pretty happy with that too, even though the question remains how much better Dirac could be. I'm wondering a bit that Audyssey measures once, computes the filters and then never checks how the actual results of using the filters are.

TL;DR: Thanks a lot for your help and pointing me in the right direction, which ultimately has led me to a very enjoyable audio system.

Cheers, Joe