Topping D90/A90 with Power Amp and Subwoofers

[concorde1]

My speaker system is:

Topping D90 via XLR to Topping A90 via XLR to power amp for speakers.

In the future I want to add two subwoofers. Such as Arendal 1723 Subwoofer 1V, or Rythmik FV15HP.

I could use the RCA output from the A90 for a subwoofer.

There are three issues raised:

1. The voltage output from RCA will be less. And as I change the volume on A90, the delta/change in volume will be different across the power amp and subwoofer.

2. The A90 can't do Low Pass for RCA and High Pass for XLR, or any filtering at all. I think subwoofers typically have configurable Low Pass, so it may not matter for the subwoofers. However, I won't have high pass for the speakers.

3. These subwoofers have RCA/XLR inputs AND outputs. Are the output signals from a subwoofer identical to the input signal? Does the subwoofer make a copy of the input signal and allow the original signal to pass through unimpeded? So can I RCA from the first subwoofer to the second subwoofer without needing to supply extra power?

How do I get around these issues and what will I need to buy? eg another D90 and A90, RME Digiface or DSP units.

For reference - https://support.arendalsound.com/hc/en-us/articles/4408600280593-Subwoofers-High-Pass-Output-
As a newbie, to me this suggests a High Pass requires another DAC.

Even if I still had my RME ADI-2 DAC, I believe with that you can only do High Pass or Low Pass for BOTH the XLR and RCA out, so that wouldn't work.

 

[Katji]

? What?

 

[Deleted member 43441]

? What?

Lol. I’ll delete that and start over.

 

[Deleted member 43441]

I’ll start over… Exactly what is the problem? If you’re looking for simultaneous amplifier and subwoofer output from a device that’s has both XLR and an RCA output… run XLR to your amplifier or speakers, and run the RCA to your subs.

 

[Deleted member 43441]

? What?

How does that sound to you better?

 

[Katji]

ok, maybe i should go take my green medication meanwhile (not Valium.)

 

[Deleted member 43441]

ok, maybe i should go take my green medication meanwhile (not Valium.)

I was talking to text, and I guess my phone had other ideas hahahaha.

 

[Katji]

...now I wonder about "self-driving" cars.

 

[Katji]

Yes, that works, basically, but no high-pass filter to main speakers. ... No high-pass filter, no subwoofer for me.

 

[Deleted member 43441]

Yes, that works, basically, but no high-pass filter to main speakers. ... No high-pass filter, no subwoofer for me.

I understand what you mean, and sometimes I like to run my mains full range, and sometimes I like to add my subs.

 

[Deleted member 43441]

My speaker system is:

Topping D90 via XLR to Topping A90 via XLR to power amp for speakers.

In the future I want to add two subwoofers. Such as Arendal 1723 Subwoofer 1V, or Rythmik FV15HP.

I could use the RCA output from the A90 for a subwoofer.

There are three issues raised:

1. The voltage output from RCA will be less. And as I change the volume on A90, the delta/change in volume will be different across the power amp and subwoofer.

2. The A90 can't do Low Pass for RCA and High Pass for XLR, or any filtering at all. I think subwoofers typically have configurable Low Pass, so it may not matter for the subwoofers. However, I won't have high pass for the speakers.

3. These subwoofers have RCA/XLR inputs AND outputs. Are the output signals from a subwoofer identical to the input signal? Does the subwoofer make a copy of the input signal and allow the original signal to pass through unimpeded? So can I RCA from the first subwoofer to the second subwoofer without needing to supply extra power?

How do I get around these issues and what will I need to buy? eg another D90 and A90, RME Digiface or DSP units.

For reference - https://support.arendalsound.com/hc/en-us/articles/4408600280593-Subwoofers-High-Pass-Output-
As a newbie, to me this suggests a High Pass requires another DAC.

Even if I still had my RME ADI-2 DAC, I believe with that you can only do High Pass or Low Pass for BOTH the XLR and RCA out, so that wouldn't work.

I’m having good luck with my Freya preamp running XLR to the amps, and RCA to my subs. Then engaging the crossover in the subwoofers, so I don’t get double/muddied bass in my set up.

Will that work for your application?

 

[Katji]

Mine is worse, and Concorde1 there also wants high-pass to main speakers. Low-pass to sub is not a problem, active/home use subs have low-pass filters, no problem to pass full-range signal to them. My problem is worse because my active speakers have no output/s other than the wires between the amplifiers and the speaker drivers......and I want to go on using EAPO. And I can't hack the speaker to get line-level output. I'd have started a thread to ask about it, but I'm still trying to conceptualise it... :-s

 

[EdTice]

Mine is worse, and Concorde1 there also wants high-pass to main speakers. Low-pass to sub is not a problem, active/home use subs have low-pass filters, no problem to pass full-range signal to them. My problem is worse because my active speakers have no output/s other than the wires between the amplifiers and the speaker drivers......and I want to go on using EAPO. And I can't hack the speaker to get line-level output. I'd have started a thread to ask about it, but I'm still trying to conceptualise it... :-s

This thread has gone completely off the rails. Let me see if I can help you guys get back on track.

If you want to add a high-pass filter to any system, they can be found for about $30 on parts express. So the lack of an HPF shouldn't be cause for concern. I have no idea where that post at arendal came from. And they certainly no more than me. But you don't need a separate DAC for an HPF on subwoofer outputs. They can be implemented as the equivalent of a Y cable and the aforementioned $30 HPF. Or you can buy a Y cable and a $30 HPF all by yourself.

However, you don't need an HPF if you set the crossover on the sub to be the -3dB point of your speakers!

You didn't mention what speakers you have. The SVS website has a tool that will show you their recommended sub to pair with your speakers and what crossover setting to use. Even if you don't buy their sub, just set the crossover where it's recommended and be done with it! Or hook up a Y cable to the RCA or XLR outputs of the DAC and add your own HPF. Really, its that easy.

It's not clear that the RCA and XLR voltages would go up and down differently when you adjust volume. In most cases the RCA output is equal to half of the XLR output. When you adjust volume they will move in equal proportion and not affect the gain structure.

Please ask some questions and lets see if we can sort this out because the complexity level has gotten very high for something so simple.

 

[concorde1]

OK so subs don't need a low pass before input, and if I set crossover of sub at -3dB point of speakers I don't need high pass.

And I'll just turn the subs up higher to compensate for the lower input.

The other question is:

can I RCA from the first subwoofer to the second subwoofer without needing to supply extra power?

In other words, like I said, does the first sub take a copy of the input signal, and pass the original signal through unimpeded?

 

[radix]

You should drive the subs from the A90, then drive the speakers from the sub. That way the sub's cross over will properly drive the speakers.

 

[EdTice]

You should drive the subs from the A90, then drive the speakers from the sub. That way the sub's cross over will properly drive the speakers.

The sub that the OP wants doesn't have a crossover on the outputs which is what brought the OP here! The explanation at Arendal is incredulous. I would tell the OP to get SVS subs. But the newer SVS models don't have HPF on the output either.

There are like a hundred threads on this. It's not at all obvious to beginners how to integrate a sub if you don't have digital bass management at the DAC. That's why SVS has that whole mechanism to tell where to set the crossover (just put in what kind of mains you have and the settings pop out).

Of course it's also amazing how scared people are to just hook things up as directed!

 

[ex audiophile]

The JLA e series subs have both low pass and hi pass filters, might help.

 

[EdTice]

OK so subs don't need a low pass before input, and if I set crossover of sub at -3dB point of speakers I don't need high pass.

And I'll just turn the subs up higher to compensate for the lower input.

The other question is:

In other words, like I said, does the first sub take a copy of the input signal, and pass the original signal through unimpeded?

You have to adjust your subwoofer's level regardless of the input. Most subwoofers have a fairly low input sensitivity (0.75V for SVS subs) so that you can drive them from low-end equipment. The amplifier gain for the sub isn't going to be the same as your mains. So you have to "level" the subwoofer.

As far as the "lower voltage," that's a misnomer. Unless you have a "fully differential" system (Read $$$), when you send "balanced" 4V there is a +2v and -2v to prevent noise. But the amplifier usually only uses *one* of them. Again there are exceptions but, in general, a 4V balanced input is converted to a 2v unbalanced before amplification. Unless you have an awful DAC, you will be running your subwoofers at -10dB or -20dB or so. You are overcomplicating things here. That's good if you want to learn but not a prerequisite to setting up your speakers. Feel free to ask more questions about this but don't get disappointed if you get pointed to existing answers!

It's hard for anybody here to say the subwoofer "takes a copy" as that isn't really what happens (although it may be fine to think about it that way) The subwoofer "through" is a Y connection like this. Electrically its absolutely the same thing as if you bought two of these and used them to split the outputs. The output of most subwoofers is nothing more, in most cases, than a convenience. https://www.amazon.com/AmazonBasics-1-Male-2-Female-RCA-Y-Adapter/dp/B01D5H8SGC?th=1 Just prettier to have it on the back of the box.

When you hook up two amps this way (subwoofer internal amp and mains amp), the voltage out of the pre-amp/DAC stays the same (because they are voltage sources) and current doubles in order to be able to drive the amplifiers. If you need to hook three or four things up this way you need a distribution amplifier as you might draw too much current from the pre-amp otherwise. But for a subwoofer amp and a main amp, this is common and just fine. Even if you were to daisy-chain many amps for multi-room distribution it would be fine as long as you stay below some (pretty loud) volume. If the pre-amplifier can deliver a certain amount of current to one amp, it can deliver half that current to each of two amps at 70% of the voltage!

If you are curious about things and want to learn, by all means, ask more questions. But don't start doing creative things just because the things that are known to work are still confusing to you!

 

[radix]

The sub that the OP wants doesn't have a crossover on the outputs which is what brought the OP here! The explanation at Arendal is incredulous. I would tell the OP to get SVS subs. But the newer SVS models don't have HPF on the output either.

Yes, I'm sorry I missed that these models do not have HPF or DSP on the output.

SVS has pointed me to Harrison Labs FMOD passive in-line filters, but I have not used them. AFAIK, all their current models are pass-through.

 

[concorde1]

OK, so my two cases are:

A90 via XLR -> first sub -> second sub -> speaker amp

A90 via XLR -> speaker amp
A90 via RCA -> first sub -> second sub

It's hard for anybody here to say the subwoofer "takes a copy" as that isn't really what happens (although it may be fine to think about it that way) The subwoofer "through" is a Y connection

In that case multiple subs need more power than one sub. I was wrong about "taking a copy". Yes it sounds obvious but I thought it was possible it worked differently. The output on the sub is the remains of the input.

Interesting, I didn't know subwoofers' input sensitivity was so low.

Forgive a newbie question:

My power amp has an input sensitivity of 4.0V. I need to supply more voltage to the power amp, so how do I know I won't supply too much to the subwoofers (more than 0.75V for SVS)? In both cases at the top of this reply.

I know I won't exceed 4.0V on the power amp because it would be extremely loud (I'm probably getting 2x JBL LSR6332), and I could measure the voltage with a voltmeter if I really wanted to (I have done this in the past with a preamp that has a lot of headroom).

To make an extreme example, suppose I supplied 3V to power amp and I have just one sub. That means in the second case above, surely the sub will be receiving 1.5V, which is too high.