How to: active bass section

[Brandon Hartwick]

@Fredrik Kansbod you're correct about the ADA conversion taking place, unfortunately there really isn't a good way around that without going to a digital preamplifier that has volume control and DSP built in. MiniDSP does make such a unit and I have been looking into it but I personally feel that for casual listening the juice just isn't worth the squeeze.

I use a Dayton 4X8 DSP unit in-between my preamplifier and power amplifier to run the panels and woofers active with no passive crossovers. Prior to that I just used a Crown XLS on the bass that had built in active crossovers, the difference was still very dramatic even with the ADA conversion taking place. I would try not to overthink it too much, the passive bass crossover sucks and that's all there is to it.

 

[Zwick]

@Fredrik Kansbod you're correct about the ADA conversion taking place, unfortunately there really isn't a good way around that without going to a digital preamplifier that has volume control and DSP built in. MiniDSP does make such a unit and I have been looking into it but I personally feel that for casual listening the juice just isn't worth the squeeze.

I use a Dayton 4X8 DSP unit in-between my preamplifier and power amplifier to run the panels and woofers active with no passive crossovers. Prior to that I just used a Crown XLS on the bass that had built in active crossovers, the difference was still very dramatic even with the ADA conversion taking place. I would try not to overthink it too much, the passive bass crossover sucks and that's all there is to it.

 

[Zwick]

I’ve gone active on bass with support of this group and am enjoying the results. Could a dsp unit be positioned to raise the effective cross over point for the panel without bypassing the panel passive crossover?

 

[Brandon Hartwick]

I’ve gone active on bass with support of this group and am enjoying the results. Could a dsp unit be positioned to raise the effective cross over point for the panel without bypassing the panel passive crossover?

That could have unexpected results, I don't see a good reason why you would run both.

 

[Zwick]

That could have unexpected results, I don't see a good reason why you would run both.

Merely to avoid the effort to bypass the panel cross over by feeding it a signal that has already been adjusted to above 200hz vs full range signal to be trimmed at 125hz by the passive crossover. Theoretical exercise. Will look at effort required to bypass the panel crossover.

 

[JonFo]

I’ve gone active on bass with support of this group and am enjoying the results. Could a dsp unit be positioned to raise the effective cross over point for the panel without bypassing the panel passive crossover?

Good to hear you are enjoying the results.

Yes, an active XO ahead of the panel could use a higher crossover point, such as 340Hz for an SL3 (stock is 250), and a steep slope, such as 24dB/Oct. L-R and the passive won't have much impact other than phase shift, which can be compensated for.

The main downside is the loss of efficiency, as all that passive circuit is still in the loop. I think you can bypass the passive with some jumpers from the terminals to the transformer tap wires without having to remove the passive elements, just disconnect the feed to them. But analog electronics is not my forte. @Leporello , could you confirm?

 

[Jazzman53]

First post here in this forum. I have lurked around for some weeks after purchasing a used set of ML reQuest's.
My first impression when hooking them up to my old system (Yamaha Home Theater gear as a pre and a Quad 405 II to drive the ML's) was disappointing. I know the ML's need another amplification so I'm not that worried. But, what should I invest in?

This thread gave me valuable info on the passive crossovers in reQuest speakers and inspiration to move to active crossover and bi-amping!

Since a few years I'm mostly using digital media but occasionally also use vinyl or other analogue sources.
As far as I understand the desribed method with a Crown amplifier with DSP will introduce two additional signal conversions (by having active crossover in the same unit as the power amplifier). I mean, the power amplifier is fed with an analogue signal (at least if a Crown amplifier is used) and the crossover needs digital signal to "work with". So a conversion to digital, processing the filter settings and then conversion back to analogue will be required.

I do believe that the improvement in sound quality still will be noticeable but wouldn't it be even better to have the active crossover while still in the digital domain?

Welcome to the forum, Fredrik.

I'm probably the only person on this forum that doesn't own ML speakers so I can't advise you on your Quests specifically, but I do have extensive experience building hybrid ESLs and bi-amping them with DSP crossovers.

I use and recommend a setup with only a single D/A conversion in the signal path. However, multiple digital conversions are so clean that you might only hear whatever coloration is added by the analog preamp.

Before I went full digital, I originally used an analog preamp feeding a DSP with multiple conversions and it sounded fine.

In any case; the sonic improvement realized by bypassing the passive crossover will far outweigh any artifacts of multiple conversions in the signal path.

If you do wish to eliminate the extra conversions; someone mentioned in an earlier post that MiniDSP has a version with a built in digital preamp.

I stream music from Tidal through a Logitech Transporter, using its digital preamp and digital output feeding the digital input on a DBX Driverack Venu 360 DSP/Crossover, with a single D/A conversion out to the amps.

The DBX Driverack Venu 360 is the sexiest piece of electronics gear that I own but it's not cheap.

Most of the people who buy my speakers are bi-amping them with the less expensive DBX Driverack PA2, which has only analog inputs, so they use an analog preamp and accept multiple conversions in the signal path, and it still sounds wonderful.

BTW; I will be happy to post my setup and tuning procedure for bi-amping with the DBX Driverack PA2 or Venu 360 DSP/Crossover.

Just do it!
Charlie

 

[JonFo]

BTW; I will be happy to post my setup and tuning procedure for bi-amping with the DBX Driverack PA2 or Venu 360 DSP/Crossover.

Oh, we'd love to have that posted to the https://www.martinloganowners.com/forums/diy-tweaks-modifications.58/ sub-form.

 

[Fredrik Kansbod]

@Fredrik Kansbod you're correct about the ADA conversion taking place, unfortunately there really isn't a good way around that without going to a digital preamplifier that has volume control and DSP built in. MiniDSP does make such a unit and I have been looking into it but I personally feel that for casual listening the juice just isn't worth the squeeze.

I use a Dayton 4X8 DSP unit in-between my preamplifier and power amplifier to run the panels and woofers active with no passive crossovers. Prior to that I just used a Crown XLS on the bass that had built in active crossovers, the difference was still very dramatic even with the ADA conversion taking place. I would try not to overthink it too much, the passive bass crossover sucks and that's all there is to it.

Welcome to the forum, Fredrik.

I'm probably the only person on this forum that doesn't own ML speakers so I can't advise you on your Quests specifically, but I do have extensive experience building hybrid ESLs and bi-amping them with DSP crossovers.

I use and recommend a setup with only a single D/A conversion in the signal path. However, multiple digital conversions are so clean that you might only hear whatever coloration is added by the analog preamp.

Before I went full digital, I originally used an analog preamp feeding a DSP with multiple conversions and it sounded fine.

In any case; the sonic improvement realized by bypassing the passive crossover will far outweigh any artifacts of multiple conversions in the signal path.

If you do wish to eliminate the extra conversions; someone mentioned in an earlier post that MiniDSP has a version with a built in digital preamp.

I stream music from Tidal through a Logitech Transporter, using its digital preamp and digital output feeding the digital input on a DBX Driverack Venu 360 DSP/Crossover, with a single D/A conversion out to the amps.

The DBX Driverack Venu 360 is the sexiest piece of electronics gear that I own but it's not cheap.

Most of the people who buy my speakers are bi-amping them with the less expensive DBX Driverack PA2, which has only analog inputs, so they use an analog preamp and accept multiple conversions in the signal path, and it still sounds wonderful.

BTW; I will be happy to post my setup and tuning procedure for bi-amping with the DBX Driverack PA2 or Venu 360 DSP/Crossover.

Just do it!
Charlie

Charlie, thank you for your input - you seems to have the setup I want - if I could afford it... ;-)

I'm right now utilizing the built-in DAC of my 20 years old Yamaha home theater receiver. I have no experience of my own with different or other DAC's but have been told, and have read, that it makes a lot of difference. Thus thinking that every conversion will add to distorsion and unwanted sound artifacts.
But, the budget is somewhat limited for now and I better start with something I can build on over time.

My thougths right now is something like this;
Streamer (right now existing Apple TV HD) -> existing Samsung TV(for video and conversion HDMI to Toslink) -> (new) miniDSP 2*4 HD -> bi-amping with one (new) class D amplifier for ML subwoofers and one (2:nd hand) Parasound A31 for ML panels.
This additional boxes would cost me approximately 15000 SEK (1400 US dollar) from what I can find out.
The biggest problem would be to bypass the internal passive crossovers, I understand it as the cabinette is glued together also on the reQuest speakers?

I'm very interested in a more specific description of your setup as you seem to have given it some thinking and testing! And if you think the miniDSP is a bad choice by any reason please let me know.

On my way of doing it!
Fredrik

 

[Jazzman53]

Oh, we'd love to have that posted to the https://www.martinloganowners.com/forums/diy-tweaks-modifications.58/ sub-form.

Done: https://www.martinloganowners.com/threads/my-bi-amp-setup-tuning-procedure.20075/#post-213789

 

[JonFo]

Done: https://www.martinloganowners.com/threads/my-bi-amp-setup-tuning-procedure.20075/#post-213789

Thanks very much, Charlie.

 

[JonFo]

And if you think the miniDSP is a bad choice by any reason please let me know.

There is nothing wrong with the MiniDSP series; just make sure to get the appropriate model given your amplification needs.
For your setup, assuming the new Class-D amp has unbalanced inputs, the base MiniDSP Flex would do the job. It is also a preamp with volume control and, even better, could run Dirac room correction ($200 option).

 

[Fredrik Kansbod]

There is nothing wrong with the MiniDSP series; just make sure to get the appropriate model given your amplification needs.
For your setup, assuming the new Class-D amp has unbalanced inputs, the base MiniDSP Flex would do the job. It is also a preamp with volume control and, even better, could run Dirac room correction ($200 option).

Thank you Jonathan for the advice!