Gains of (active) bi-/tri-/quad-amping

[nicoleise]

I know that first question wasn't a real ask...

But I'm just going to set this down here and you can decide what's right for you:

Buckeye Amps

Buckeye Amps utilizes the most advanced audio amplifier technologies available. Authorized seller for Hypex and Purifi Class D amplifiers. Based in the US. Free shipping and worldwide service!

www.buckeyeamp.com

Thanks, I looked into Hypex before, wasn't aware of the new NCx version though. They do seem really appealing.

I'm unsure of a few aspects of the build (center, subwoofers), so it's too early for me to buy amps yet (or they'd be already hooked up to the speakers, even if temporary).

But I'll keep those in mind, shipping shouldn't be too insane if buying multiple units together. And perhaps there's a more local (to me) reseller as well.

 

[ryanosaur]

Thanks, I looked into Hypex before, wasn't aware of the new NCx version though. They do seem really appealing.

I'm unsure of a few aspects of the build (center, subwoofers), so it's too early for me to buy amps yet (or they'd be already hooked up to the speakers, even if temporary).

But I'll keep those in mind, shipping shouldn't be too insane if buying multiple units together. And perhaps there's a more local (to me) reseller as well.

Whereabout are you located?
Here in the US? Elsewhere?

 

[nicoleise]

Whereabout are you located?
Here in the US? Elsewhere?

I'm in Denmark.
Been to the US many times though, so I know I should clarify that Denmark is not the capital of Sweden.

Well, except retired USAF guys. They always seem to know exactly where Denmark is.

 

[AcuDefTechGuy]

I see. Thanks for the clarification.

As I'm going to be installing four subwoofers in this room also, my goal with this isn't really "quantity of bass". If bi-amping increases the fidelity of the bass, I'd put that down as an advantage though.

I've had dual 10" speakers, and family members still have dual 8s or single 15s. I get what you're saying.

I have no complaints about the bass output in these speakers, its more the case that I wonder if the top end could benefit from the amp not also driving the bass woofers.

EDIT: I should add that it takes cranking the volume up quite a bit to make them actually liven up in the bass region, more so than e.g. my dual 10s. So one potentially positive side effect of bi-amping might be to boost the bass region (perhaps only a variable degree and at lower volumes - difficult to say as it shouldn't turn into the loudness function or sound like a Sonos speaker). But much of this I suspect would be possible with a DSP regardless of bi-amping.

Yeah, I think the only advantage of bi-amping any speaker is for the bass control - you could easily reduce the bass amount without having to use EQ.

Now others may talk about other advantages (fidelity/quality). But to me the only advantage is having better control of the bass.

 

[ryanosaur]

I'm in Denmark.
Been to the US many times though, so I know I should clarify that Denmark is not the capital of Sweden.

Well, except retired USAF guys. They always seem to know exactly where Denmark is.

There are Hypex dealers over there in the EU and UK.
Apollon and Nord are the two that come to mind most readily. I’m pretty certain I’ve seen somebody in France and I think Germany, perhaps.
Buying direct from Hypex in the Netherlands is possible from their affiliate DIY Class D, specifically you would probably want 2ea of the Nilai monoblock kits.

I’ve built the older DIY version of the NC400. It’s not difficult, especially if you have a little electrical know-how.

Other good Class D options would be Purifi and Pascal Amps.
There are 2 other companies I’ve heard discussed but have not seen any bench testing for, one of which is Sylph Audio.

Happy hunting!

 

[nicoleise]

There are Hypex dealers over there in the EU and UK.
Apollon and Nord are the two that come to mind most readily. I’m pretty certain I’ve seen somebody in France and I think Germany, perhaps.
Buying direct from Hypex in the Netherlands is possible from their affiliate DIY Class D, specifically you would probably want 2ea of the Nilai monoblock kits.

I’ve built the older DIY version of the NC400. It’s not difficult, especially if you have a little electrical know-how.

Other good Class D options would be Purifi and Pascal Amps.
There are 2 other companies I’ve heard discussed but have not seen any bench testing for, one of which is Sylph Audio.

Happy hunting!

Thanks again for the very useful information.
Purify I also looked at previously as well. They're based in Denmark I believe (at least almost all the management is Danish). And they offer both stereo and mono boards.

And yes, building some custom enclosure(s) with these modules and good PSU(s) is also an interesting option.

I'm an electrical engineer and design and build electrical control systems every day. I'm also able to provide declarations of conformity, which in the EU essentially means that it's legally recognized as a product rather than some DIY solution.

I don't know if this is another of those "chasing a non issue", but I often thought about getting digital signals from an AVP/decoder to a separate DSP and then (still digitally) to amps. It doesn't seem to readily exist? And "hacking something" is everything but simple (I²C for example is typically very length sensitive so it's difficult to extend the wiring significantly).

It seems like a decoder that "refractors" the decoded streams into optical outputs for example, would be handy for this. But a very limited use case also. I can definitely recognize that. And again, perhaps not really a practical or audible concern that signals are converted a few times more.

 

[ryanosaur]

Thanks again for the very useful information.
Purify I also looked at previously as well. They're based in Denmark I believe (at least almost all the management is Danish). And they offer both stereo and mono boards.

And yes, building some custom enclosure(s) with these modules and good PSU(s) is also an interesting option.

I'm an electrical engineer and design and build electrical control systems every day. I'm also able to provide declarations of conformity, which in the EU essentially means that it's legally recognized as a product rather than some DIY solution.

I don't know if this is another of those "chasing a non issue", but I often thought about getting digital signals from an AVP/decoder to a separate DSP and then (still digitally) to amps. It doesn't seem to readily exist? And "hacking something" is everything but simple (I²C for example is typically very length sensitive so it's difficult to extend the wiring significantly).

It seems like a decoder that "refractors" the decoded streams into optical outputs for example, would be handy for this. But a very limited use case also. I can definitely recognize that. And again, perhaps not really a practical or audible concern that signals are converted a few times more.

If you aren't familiar with it, look at Dante integration. Everything is sent over ethernet. Dunno if that is exactly what you are thinking, but it is the closest thing I've seen that sounds similar.

That said, with your presumed abilities, you could probably quite easily assemble a good Purifi Amp with Hypex Power Supplies. Just make certain you get a SMPS that will fully power the Amp module.

Between Purifi and Hypex, there really is no audible benefit... you are looking at degrees of refinement outside our ability to hear.

Some of those companies, Nord, Apollon, I think KJF is another in the UK... they offer upgraded OP Amps and other stuff... Dunno if it is really worthwhile or not... but you can see test results on ASR for many Hypex and Purifi options. The base offerings are pretty much all top of the heap.

 

[highfigh]

I'm in Denmark.
Been to the US many times though, so I know I should clarify that Denmark is not the capital of Sweden.

Well, except retired USAF guys. They always seem to know exactly where Denmark is.

Jutland? I know the former head of US operations for Jamo.

 

[highfigh]

Yeah, I think the only advantage of bi-amping any speaker is for the bass control - you could easily reduce the bass amount without having to use EQ.

Now others may talk about other advantages (fidelity/quality). But to me the only advantage is having better control of the bass.

And eliminating insertion loss & phase shift from passive filters.

 

[TLS Guy]

And eliminating insertion loss & phase shift from passive filters.

Analog active crossovers have the same phase shifts as analog ones. Active digital filters can be linear phase. I have never worked with digital crossovers.

 

[highfigh]

Analog active crossovers have the same phase shifts as analog ones. Active digital filters can be linear phase. I have never worked with digital crossovers.

I wasn't thinking that he would be using an analog crossover- I can't imagine a way for an analog crossover to do what something like a MiniDSP or anything else can, with levels, phase, slope, frequency selection, symmetry/assymetry, etc.

Did you post a photo of an old Crown rack mount crossover?

 

[TLS Guy]

I wasn't thinking that he would be using an analog crossover- I can't imagine a way for an analog crossover to do what something like a MiniDSP or anything else can, with levels, phase, slope, frequency selection, symmetry/assymetry, etc.

Did you post a photo of an old Crown rack mount crossover?

Yes, a VFX-2. It is the crossover between the four KEF B139 bass drivers, and the midrange driver of the rear back lines. I did a complete refurbishment of it a few years ago. So all the ICs are updated to more modern lower noise devices. Crossover is set at 180 Hz. I think I bought it in 1976 or 77.

You can see it here right above the amp controller, and 3 highly modified Shure SR 106 crossover above that. They might be even older. I used to use them in sound reinforcement gigs.

I believe in getting my money's worth from my gear. I look after it and maintain it. That is the best way to build satisfying long lasting systems. Then you have excellent budget friendly systems.

I would say the bulk of my gear is antique, but none the worse for it. It's not made in China either.

As you know I hate junk and I can spot it a mile off.

 

[nicoleise]

If you aren't familiar with it, look at Dante integration. Everything is sent over ethernet. Dunno if that is exactly what you are thinking, but it is the closest thing I've seen that sounds similar.

I didn't know Dante. It's an encapsulation method (which makes a lot more sense than e.g. inventing new pointless plugs like HDMI) since it (IP) is universal and is a well established method of transmitting digital data with integrety and great bandwidth. I actually have been looking for something similar (distribution of A/V, antenna, etc. in PDS/network cables) as a Danish system did this in the 90'es and 00'es but was discontinued and never updated to modern standards. So good share nonetheless.

What I meant was that in a decoder (like an AVP), the multichannel digital input stream is processed according to it's content and your configuration of speakers, and the output is also digital (within the box) but is now discrete channels of information. Hence the decoder did it's job. It would seem convinient to be able to extract this information, for example through IP or optical links, for use with an external DSP. Instead, any output (outside the box) of an AVP is typically analogue (fx preouts).

I think this - like many other "odd" limitations - is essentially due to digital copy prevention, and if that assumption holds then likely it wont change. Especially since this limitation doesn't seem to exist with professional gear (as an example, DENON professional uses Dante but DENON does not). Just wondering if I'm overlooking something.

(I don't think this is of audible concern, the extra ADC and DAC steps, but it's just silly having to route a cable per channel, especially with longer runs)

 

[nicoleise]

Jutland? I know the former head of US operations for Jamo.

No, I'm on Sealand/Sjælland (the larger of the isles, where the capital Copenhagen is). That being said, national geography really isn't much of a "divider" here: https://www.mylifeelsewhere.com/country-size-comparison/denmark/united-states

 

[nicoleise]

I wasn't thinking that he would be using an analog crossover- I can't imagine a way for an analog crossover to do what something like a MiniDSP or anything else can, with levels, phase, slope, frequency selection, symmetry/assymetry, etc.

Yep, your assumption is spot on. Not sure if it will be a miniDSP or something else. I wont be bi-amping my main speakers though (per the advice in this thread), so the DSP will instead be used for time aligning and tuning the system.

 

[highfigh]

Yes, a VFX-2. It is the crossover between the four KEF B139 bass drivers, and the midrange driver of the rear back lines. I did a complete refurbishment of it a few years ago. So all the ICs are updated to more modern lower noise devices. Crossover is set at 180 Hz. I think I bought it in 1976 or 77.

I had a VFX-2A and I don't remember it being noise-free. IIRC, those had TLO-72 OP-Amps, thought about changing to TLO-74 for the reason you changed yours.

 

[TLS Guy]

I had a VFX-2A and I don't remember it being noise-free. IIRC, those had TLO-72 OP-Amps, thought about changing to TLO-74 for the reason you changed yours.

Yes.

 

[everettT]

Yeah, I think the only advantage of bi-amping any speaker is for the bass control - you could easily reduce the bass amount without having to use EQ.

Now others may talk about other advantages (fidelity/quality). But to me the only advantage is having better control of the bass.

Active DSP of the whole speaker allows for linear phase and being time aligned.

Here is a take from a manufacturer on his personal speakers.

Post in thread 'Active crossovers measurably better?' https://audiosciencereview.com/forum/index.php?threads/active-crossovers-measurably-better.2285/post-62387

 

[AcuDefTechGuy]

Active DSP of the whole speaker allows for linear phase and being time aligned.

Here is a take from a manufacturer on his personal speakers.

Post in thread 'Active crossovers measurably better?' https://audiosciencereview.com/forum/index.php?threads/active-crossovers-measurably-better.2285/post-62387

Yeah, like I said, there are other THEORETICAL advantages.

But in real life practice, having owned 100% active systems in the past (Linkwitz Orion 3.2.1), I don't HEAR any of those advantages compared to passive systems, except for the active BASS control.

 

[highfigh]

Yeah, like I said, there are other THEORETICAL advantages.

But in real life practice, having owned 100% active systems in the past (Linkwitz Orion 3.2.1), I don't HEAR any of those advantages compared to passive systems, except for the active BASS control.

It's hard to hear the specific differences if you can't compare the speaker system using a complete active crossover, then with the passive version.

It would be an interesting experiment, but switching between them quickly and assuring equal SPL from each would be tricky.