Thinking about modifing my passive RM40 to active.

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rlsrls

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Thinking about modifing my passive RM40 to active.
« on: 27 Sep 2009, 05:54 pm »
I find I am spending the majority of my work / spare time in my home office so I am going to upgrading that setup.  My plan is to build a dedicated Mac Pro based music server capable of 24/192. I am looking at both the Berkley Alpha DAC and the Weiss Minavara DAC, hoping for an audition of these or similar DACs.  Will be relocating my circa 2001 RM40's (spirial) to the home office and my 626Rs to the living room for HT duties.

Has anyone converted RM40's from passive to active?  What are your impressions?  How involved? Estimated costs?  Other then extra amps and Berringer, is it basically just wire?

Seems like a lot of data conversions going from digital to analog back to digital back to analog.

Thanks



John Casler

Re: Thinking about modifing my passive RM40 to active.
« Reply #1 on: 27 Sep 2009, 08:50 pm »
I find I am spending the majority of my work / spare time in my home office so I am going to upgrading that setup.  My plan is to build a dedicated Mac Pro based music server capable of 24/192. I am looking at both the Berkley Alpha DAC and the Weiss Minavara DAC, hoping for an audition of these or similar DACs.  Will be relocating my circa 2001 RM40's (spiral) to the home office and my 626Rs to the living room for HT duties.

Has anyone converted RM40's from passive to active?  What are your impressions?  How involved? Estimated costs?  Other then extra amps and Berringer, is it basically just wire?

Seems like a lot of data conversions going from digital to analog back to digital back to analog.

Thanks

The D-OXO can be added to any of the VMPS Ribbon Monitors.

It involves:

Purchasing the D-OXO package $750 which includes:
1) D-OXO
2) Programming for your speaker and drivers
3) Digilog Bridge for your speakers and 2way biamped operation
4)  An extra pair of binding posts
5) Any caps or resistors needed for your drivers
6)  Instructions

If you know your way around a speaker and have the ability to solder you need to do the following:

1) Install binding posts
2) Direct wire Tweeter, All panels, and both Woofers to their specific binding posts
3) Add any in line parts.
4) Procure amps to drive the sections depending on rather you are biamping or tri-amping

As far as purchasing an exotic DAC only to run it through the ADC of the D-OXO. . .It might be more prudent to use the diagram below and save the money for a 4-6 channel preamp and the amps themselves.  You can also send your D-OXO to Scott Endler to have the on-board DACs upgraded/modded. 
http://mysite.verizon.net/vze4c5pt/id14.html

If your only source is the music server, then it would be wise and cheaper to consider keeping the signal "DIGITAL" from the server to the D-OXO, and the only conversion occurs as the signal exits the D-OXO to your 4-6 channel preamp volume control.

Where can you find a 4-6 channel volume control?  Any of the now "out of date" high quality PrePros out there that have a really high quality volume control and 5.1-7.1 analog inputs will do.  Theta, Bryston, NuFORCE, Krell, Lexicon, and any number of them are available used for pennies on the dollar.  You are NOT looking for anything except the ability to input 4-6 analog channels and have volume (gain) control over them.

You then run the PrePro outputs to your amps and from the amps to the respective binding posts.

Brian would have to offer up what caps or parts might also be needed (if any) for your respective drivers to adjust efficiencies if needed beyond the capabilities of the D-OXO's abilities.


rlsrls

  • Jr. Member
  • Posts: 8
Re: Thinking about modifing my passive RM40 to active.
« Reply #2 on: 27 Sep 2009, 09:15 pm »
Hey John, Thanks for the quick response. 

Pez

Re: Thinking about modifing my passive RM40 to active.
« Reply #3 on: 28 Sep 2009, 12:03 am »
Speaking from experience full active is definately the way to go. The wonderful thing full active affords you is a lot of flexibility. For instance I'm running a relatively cheap, buy powerful QSC pro amp for the bass section on my 40s that puts out somewhere in the neighborhood of 300-400 watts per channel. And for the mids/highs I'm running a wonderful sounding Bella EXtrememere mere 60 watts. You'd be surprised how far 60 watts will go when you don't have to output 30 hz bass tones.

This is actually a perfect combination of grace and power. I also am currently procuring parts for a low watt (5-15 watt) SET tube amp for the tweeters. Where most people chose to go with pure solid state or pure tube setups active crossing allows you to customize your setup and get the absolute best of both worlds without the detriments of either. I have a ballsy lowend with tons of transients and bass to die for and a smooth silky top end. There is pretty much nothing to lose and everything to gain with active, other than price restrictions I don't get why more people don't do it.  :scratch: 

Russtafarian

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Re: Thinking about modifing my passive RM40 to active.
« Reply #4 on: 28 Sep 2009, 04:05 am »
I?ve been meaning to write this up and this gives me an excuse to.  Here?s what I did to my RM30s.  The same approach would work with the RM40s.

I removed all crossover components except the mid panel to FST crossover.  The mid panel lowpass coil, FST highpass coil, cap and L-pad are still used but everything else is gone.

The three woofers are wired directly to one set of binding post and are driven by a DCX2496 and digital amp.  DCX crossover points are 30hz and 284hz with 24db L-R filters.  DCX eq filters are used to smooth in-room response.

Mid panels and FST are wired to the other set of binding posts and are driven directly by Quicksilver tube monoblocks with in-line 400hz 1st order highpass filters between preamp and amp.

So the woofers use digital filters and amps to increase damping factor and smooth out room anomalies below 300hz.  The mid panels and FST stay completely analog above 300hz using simple passive filters and tube amplification. 

This is the best of both worlds.  Bass timbre, extension and control is a big step forward over stock RM30s.  But the bigger improvement is the midrange.  Those mid panels now have SOTA depth and detail, no other way to describe it.  I?m tempted to say ?my RMs sound better than any of your RMs?, but I won?t be that presumptuous.  I will say that my digilog conversion is a smashing success.

One other note.  Since both digital and analog are feed by the two outputs on my preamp, volume and switching control is still simple.  No need for a multi-channel preamp.

Russ

Housteau

Re: Thinking about modifing my passive RM40 to active.
« Reply #5 on: 29 Sep 2009, 02:36 pm »
As far as purchasing an exotic DAC only to run it through the ADC of the D-OXO. . .It might be more prudent to use the diagram below and save the money for a 4-6 channel preamp and the amps themselves.  You can also send your D-OXO to Scott Endler to have the on-board DACs upgraded/modded. 
http://mysite.verizon.net/vze4c5pt/id14.html

If your only source is the music server, then it would be wise and cheaper to consider keeping the signal "DIGITAL" from the server to the D-OXO, and the only conversion occurs as the signal exits the D-OXO to your 4-6 channel preamp volume control.

Technically and logically this does appear like the right thing to do.  But, I have found that this is not the best way to go for sonics.  I have a highly modded Behringer and still use the analog inputs only, as using the digital in does not sound good to me even though it is much better than the standard unit.  I much prefer using a separate DAC and then going through a second digital conversion within the DCX.  Something bad happens when breaking into the middle of the DCX's conversion process by going digital in.  Conversely, by allowing the DCX to complete the full process of going A-D-A, it becomes extremely transparent.  Even the stock units share this amazing quality.

A friend of mine just inserted a stock DCX into his high dollar extremely transparent system for biamping and you could not tell it had been added in, other than for the positive benefits of biamping.

However, if you run a stock DCX using the analog input you cannot just use a preamp in front of it to set your normal listening level either.  This will not drive the DCX adequately as it needs to be maxed out on it's input in order to work at full resolution.  My modded unit takes care of this problem with the addition of a separate analog control board allowing it to act as my preamp.  A stock unit will need attenuators between it and your amplifiers that will allow your preamp to drive it at a higher gain setting.  Scott Endler has these as a part of his mods.  These attenuators will also allow you to set the balance between your amplifiers in the analog domain.  Using the digital volume controls on the DCX risks the loss of resolution.  You are throwing bits away.  One could also use a multichannel preamp as John suggests for using the digital in, but you would then need to attenuate the input from the source as not to overdive the DCX analog input. 
« Last Edit: 29 Sep 2009, 10:56 pm by Housteau »

John Casler

Re: Thinking about modifing my passive RM40 to active.
« Reply #6 on: 29 Sep 2009, 07:04 pm »
As far as purchasing an exotic DAC only to run it through the ADC of the D-OXO. . .It might be more prudent to use the diagram below and save the money for a 4-6 channel preamp and the amps themselves.  You can also send your D-OXO to Scott Endler to have the on-board DACs upgraded/modded. 
http://mysite.verizon.net/vze4c5pt/id14.html

If your only source is the music server, then it would be wise and cheaper to consider keeping the signal "DIGITAL" from the server to the D-OXO, and the only conversion occurs as the signal exits the D-OXO to your 4-6 channel preamp volume control.

Technically and logically this does appear like the right thing to do.  But, I have found this not to be the best way to go for sonics.  I have a highly modded Behringer and still use the analog inputs only, as using the digital in does not sound good to me even though it is much better than the standard unit.  I much prefer using a separate DAC and then going through a second digital conversion within the DCX.  Something bad happens when breaking into the middle of the DCX's conversion process by going digital in.  Conversely, by allowing the DCX to complete the full process of going A-D-A, it becomes extremely transparent.  Even the stock units share this amazing quality.

A friend of mine just inserted a stock DCX into his high dollar extremely transparent system for biamping and you could not tell it had been added in, other than for the positive benefits of biamping.

However, if you run a stock DCX using the analog input you cannot just use a preamp in front of it to set your normal listening level either.  This will not drive the DCX adequately as it needs to be maxed out on it's input in order to work at full resolution.  My modded unit takes care of this problem with the addition of a separate analog control board allowing it to act as my preamp.  A stock unit will need attenuators between it and your amplifiers that will allow your preamp to drive it at a higher gain setting.  Scott Endler has these as a part of his mods.  These attenuators will also allow you to set the balance between your amplifiers in the analog domain.  Using the digital volume controls on the DCX risks the loss of resolution.  You are throwing bits away.  One could also use a multichannel preamp as John suggests for using the digital in, but you would then need to attenuate the input from the source as not to overdive the DCX analog input.

What Dave is talking about looks like this:


Pez

Re: Thinking about modifing my passive RM40 to active.
« Reply #7 on: 29 Sep 2009, 08:26 pm »
My setup is similar to this one. I use my DCX as the volume control and do not utilize a preamp as I only have one source. This eliminates the need for a preamp all together and allows for a more direct path.