[subsonic1050]

This topic has been the bane of my existence for a few years now. I very frequently am using an integrated amplifier which does not have any pre-outs or subwoofer outputs. I want to use the volume control of the integrated amp as it has a high quality potentiometer rather than using the volume control in my DAC.

My system is as follows:
Main Speakers: GR Research NX-Treme's
Subwoofers: (2) triple OB subs and (2) Rythmik F15HP sealed subwoofers
Integrated Amp: Line Magnetic 845 Premium
DAC: Holo Audio Spring 3 KTE with Preamp module
Source: Bluesound Node 2i
Also have available a MiniDSP SHD unit which I currently have the subwoofers only hooked up to.

I'll explain my current setup. I have the Bluesound feeding into the Holo Spring then directly to my Line Magnetic amp. In addition, I'm using a 2nd digital output from the Bluesound to the MiniDSP, which is then providing signal to the subwoofers. However, this means I have 2 independent volume controls - the subs are controlled separately from the main volume which is certainly not ideal. I do like being able to put a crossover on the subs with the MiniDSP. I want to avoid passing the main signal through the MiniDSP to the Line Magnetic if possible.

One alternative would be to use the volume control on the Holo Spring for everything as I could use a digital output from the Spring to the MiniDSP. It at least has a potentiometer rather than a digital volume control, but I'm not sure exactly how quality the volume control is. However, it would be upstream from the Line Magnetic and MiniDSP and should be able to control both.

The other option would be to use line level inputs and get rid of the MiniDSP altogether - but my understanding is that the line level inputs may not be ideal with a tube amplifier? Also I would miss out on the benefits of the MiniDSP for bass control but I'm not married to keeping it.

Does anyone have an idea for the best way to physically connect the subwoofers to the system?

[richidoo]

You are wise to avoid running main speakers through miniDSP.

Using the analog DAC VC would be the easiest and best solution but it would not work with other sources like TT, FM, etc.

An alternative is to use your subs' speaker level inputs, if so equipped. You can parallel them with main speakers safely.
The built in filters of Rythmik amps sound good and are flexible enough if the sub is positioned well.

If your subs don't have speaker level input, you can DIY an adapter. Depending on the voltage output of your amplifier, a simple resistor network can attenuate the speaker signal by -20dB, (10 times less voltage) or -26dB (20 times less voltage) then you can further adjust it with subwoofer gain control to match main speakers.

https://www.epanorama.net/circuits/speaker_to_line.html/
https://electronics.stackexchange.com/questions/100292/speaker-level-to-line-level
https://audiokarma.org/forums/index.php?threads/speaker-level-to-line-level-conversion.960820/
https://www.fullcompass.com/prod/260221-xantech-sllc1-speaker-level-to-line-level-converter

The amp output is single ended signal, and the L-Pad and the filtering is single ended circuits, so use the RCA input on the subs. If they don't have RCA input, check with Rythmik that their balanced input circuit can handle an RCA>XLR adapter, as not all balanced input ICs like to run on one leg only.

[nlitworld]

I also built my own DIY converter for my subs.



They are quite simple to build as I grabbed small plastic boxes online, rca input jack and 2 .25W resistors. I tried the 10k resistor in there, but I needed to up it to a 20k resistor as otherwise my subs were barely above 0 to get proper volume. A 20k resistor dropped the volume to where I have much more control blending my subs into my speakers.

Output fron this converter box could go into your dsp if you wanted to really control phase and crossovers, or just y-connector to your subs "LINE IN" connection and use the controls on your subs independently.

Hope this helps.

[Rusty Jefferson]

Since the dac has the preamp module, why wouldn't you just take the outputs from the dac (Y connection on RCA if your dsp doesn't have balanced input) and feed the amp and the dsp from the dac/preamp? I don't see specs for the dac/pre but I'm sure it's got crazy low output impedance and can drive both. Am I missing something?

[Danny Richie]

I love the people that frequent my circle. They are exceptionally helpful.

Build yourself a pair of these: https://www.youtube.com/watch?v=65eFr2rKy3M&t=56s

[subsonic1050]

Thanks everybody. Danny, I have already built an in-line filter for the mains - but unsure how that helps with connecting subwoofers? I did actually put an unfiltered output into the converter, which I had intended to use as a subwoofer output. However, that output is full gain - I want to control the volume of both the main speakers and the subwoofers at the same time.

Maybe it is just easiest to use the high level inputs on all the subs. Why do people seem to dislike using the high level inputs - especially with tube amps?

[Danny Richie]

Thanks everybody. Danny, I have already built an in-line filter for the mains - but unsure how that helps with connecting subwoofers? I did actually put an unfiltered output into the converter, which I had intended to use as a subwoofer output. However, that output is full gain - I want to control the volume of both the main speakers and the subwoofers at the same time.

Maybe it is just easiest to use the high level inputs on all the subs. Why do people seem to dislike using the high level inputs - especially with tube amps?

If you make it into a Y then you can send the unfiltered signal to to the subs and the filtered signal to the mains then control both with your front end.