iz_thewiz Posted July 27 Share Posted July 27 Hi all, I am considering expanding my current system to include a stereo power amplifier and compatible bookshelf hi-fi speakers. My current system is essentially a mix of hi-fi & digital components both of which are monitored from the digital output stage. System components: Technics SL-1200 MK2 turntable Jelco TK-850S tonearm Nagaoka MP-200 phono cartridge/stylus Graham Slee Reflex M phono pre-amplifier RME Fireface 800 Coleman Audio M3PH MK2 monitor controller Dorrough 40-C2 loudness monitors Studio monitors (KRK Rokit 8 G2) The Coleman Audio unit is capable of hosting 4x stereo XLR inputs, and can be switched to 3x stereo outputs. It has a 47 position stepped level control that tracks to ±.05dB, and is completely passive in its design. Ideally, I was hoping to split the output stage from the phono pre-amplifier and split one stereo output direct into the RME unit, and the second stereo output direct into an available Coleman audio input, then switch outputs between the digital and analogue systems. I have access to two Radial LX-3 units, which are line level splitters; 1x mono input (balanced or un-balanced) to 3x mono outputs (2x Jensen transformer isolated, 1x direct output). I have utilised these in the past to perform similar duties with my system and it worked flawlessly. However, upon recent testing I ran into a capacitive coupling issue, which was confirmed by both the manufacturer of the phono stage and the Radial units. It was due to the cable termination on the TRS connector and the interfacing with the LX-3 unit. The phono stage outputs are RCA connectors, so unless I attempt to re-solder the cables TRS connector so this signal flow can be achieved, I’m somewhat at a loss as to how I can split the signal of the phono stage while avoiding the capacitive coupling issue. Follow up question; as the Coleman Audio unit utilises balanced I/O connections and if I was to incorporate a stereo power amplifier with balanced XLR inputs, would the monitor controller be sufficient to drive signal into the stereo power amplifier? Thanks for the read. Link to comment Share on other sites More sharing options...
Snoopy8 Posted July 29 Share Posted July 29 Sorry, no pro audio experience. Maybe this can prompt a pro audio person on forum to answer? 1 Link to comment Share on other sites More sharing options...
Misternavi Posted July 29 Share Posted July 29 On 27/7/2023 at 10:55 PM, iz_thewiz said: Technics SL-1200 MK2 turntable Jelco TK-850S tonearm Nagaoka MP-200 phono cartridge/stylus Graham Slee Reflex M phono pre-amplifier RME Fireface 800 Coleman Audio M3PH MK2 monitor controller Dorrough 40-C2 loudness monitors Studio monitors (KRK Rokit 8 G2) so from the phono pre does it go into the RME to convert to digital and then back to analogue XLR to connect to the Passive volume control (Coleman)? On 27/7/2023 at 10:55 PM, iz_thewiz said: Follow up question; as the Coleman Audio unit utilises balanced I/O connections and if I was to incorporate a stereo power amplifier with balanced XLR inputs, would the monitor controller be sufficient to drive signal into the stereo power amplifier? whenever running a passive attenuator it’s best to keep cables as short as possible. i have a passive pre also and the interconnect between the 2 units is 25cm and it’s a low capacitance cable. if you need more than a metre of cable between the colman and power amp run an active buffer between the 2 units or ditch the colman and RME and use a active pre with SE and BAL input and XLR out. Link to comment Share on other sites More sharing options...
iz_thewiz Posted July 31 Author Share Posted July 31 On 30/07/2023 at 4:20 AM, Misternavi said: so from the phono pre does it go into the RME to convert to digital and then back to analogue XLR to connect to the Passive volume control (Coleman)? whenever running a passive attenuator it’s best to keep cables as short as possible. i have a passive pre also and the interconnect between the 2 units is 25cm and it’s a low capacitance cable. if you need more than a metre of cable between the colman and power amp run an active buffer between the 2 units or ditch the colman and RME and use a active pre with SE and BAL input and XLR out. Thanks for your reply. Yes, signal is fixed from the phono pre direct to the AD/DA interface via a 1/4" line input, then 1/4" line output out to a stereo XLR input on an available input on the Coleman unit. Just to clarify, the Coleman unit is a passive balanced XLR I/O system. The interconnect from the phono stage to the 1/4" line input of the AD/DA is 1 metre (capacitance = 55pf per metre), the rest of the cabling (audio) is Mogami Gold with various terminations (capacitance = 65pf per metre). I think the solution here in my case is to source another cable with a RCA to 1/4" TS termination. The cable manufacturer I'm currently using for interconnecting the phono stage to the AD/DA system has confirmed with me that they can perform this termination (RCA to 1/4") to order, which should in theory resolve the capacitive coupling issue I was experiencing with the RCA-TRS termination. Keep the cable single ended and un-balanced, pass it through the isolation transformer and let the splitter units perform the balanced conversion internally. Do you agree? Link to comment Share on other sites More sharing options...
Misternavi Posted July 31 Share Posted July 31 16 minutes ago, iz_thewiz said: I think the solution here in my case is to source another cable with a RCA to 1/4" TS termination. The cable manufacturer I'm currently using for interconnecting the phono stage to the AD/DA system has confirmed with me that they can perform this termination (RCA to 1/4") to order, which should in theory resolve the capacitive coupling issue I was experiencing with the RCA-TRS termination. Keep the cable single ended and un-balanced, pass it through the isolation transformer and let the splitter units perform the balanced conversion internally. Do you agree? Waaaaaaaayyyy too complicated! Bypass the RME I would do this: GS Phono>>RCA>>ISO transformer XLR out>>Colman Volume control>> Power amp or Active speakers JUST KEEP your cables as short as POSSIBLE. Or a simpler version would be GS phono>> 10K stepped attenuator ($20 on eBay) >> Power amp Link to comment Share on other sites More sharing options...
iz_thewiz Posted July 31 Author Share Posted July 31 5 minutes ago, Misternavi said: Waaaaaaaayyyy too complicated! Bypass the RME I would do this: GS Phono>>RCA>>ISO transformer XLR out>>Colman Volume control>> Power amp or Active speakers JUST KEEP your cables as short as POSSIBLE. Or a simpler version would be GS phono>> 10K stepped attenuator ($20 on eBay) >> Power amp I think you misunderstood my intended signal flow: Phono stage output (stereo) - splitter input - splitter output 1 (dual mono) to RME input (stereo) - splitter output 2 (dual mono) to Coleman input (stereo). The RME interface is essential for recording and playback purposes. Link to comment Share on other sites More sharing options...
Misternavi Posted July 31 Share Posted July 31 6 minutes ago, iz_thewiz said: I think you misunderstood my intended signal flow: Phono stage output (stereo) - splitter input - splitter output 1 (dual mono) to RME input (stereo) - splitter output 2 (dual mono) to Coleman input (stereo). The RME interface is essential for recording and playback purposes. it should be fine then. Link to comment Share on other sites More sharing options...
Cloth Ears Posted August 1 Share Posted August 1 On 27/07/2023 at 10:55 PM, iz_thewiz said: Hi all, I am considering expanding my current system to include a stereo power amplifier and compatible bookshelf hi-fi speakers. My current system is essentially a mix of hi-fi & digital components both of which are monitored from the digital output stage. System components: Technics SL-1200 MK2 turntable Jelco TK-850S tonearm Nagaoka MP-200 phono cartridge/stylus Graham Slee Reflex M phono pre-amplifier RME Fireface 800 Coleman Audio M3PH MK2 monitor controller Dorrough 40-C2 loudness monitors Studio monitors (KRK Rokit 8 G2) The Coleman Audio unit is capable of hosting 4x stereo XLR inputs, and can be switched to 3x stereo outputs. It has a 47 position stepped level control that tracks to ±.05dB, and is completely passive in its design. Ideally, I was hoping to split the output stage from the phono pre-amplifier and split one stereo output direct into the RME unit, and the second stereo output direct into an available Coleman audio input, then switch outputs between the digital and analogue systems. I have access to two Radial LX-3 units, which are line level splitters; 1x mono input (balanced or un-balanced) to 3x mono outputs (2x Jensen transformer isolated, 1x direct output). I have utilised these in the past to perform similar duties with my system and it worked flawlessly. However, upon recent testing I ran into a capacitive coupling issue, which was confirmed by both the manufacturer of the phono stage and the Radial units. It was due to the cable termination on the TRS connector and the interfacing with the LX-3 unit. The phono stage outputs are RCA connectors, so unless I attempt to re-solder the cables TRS connector so this signal flow can be achieved, I’m somewhat at a loss as to how I can split the signal of the phono stage while avoiding the capacitive coupling issue. Follow up question; as the Coleman Audio unit utilises balanced I/O connections and if I was to incorporate a stereo power amplifier with balanced XLR inputs, would the monitor controller be sufficient to drive signal into the stereo power amplifier? Thanks for the read. What bookshelf speakers were you thinking of to replace the G2's? They're PFG as far as I'm concerned. Link to comment Share on other sites More sharing options...
stereo coffee Posted August 1 Share Posted August 1 On 30/07/2023 at 6:20 AM, Misternavi said: whenever running a passive attenuator it’s best to keep cables as short as possible. Can you qualify this in terms of what you suggest as " a passive attenuator " as it certainly does not apply to other passive attenuators that can be used with cabling up to 6.5 metres. with perfect result. Link to comment Share on other sites More sharing options...
Misternavi Posted August 1 Share Posted August 1 34 minutes ago, stereo coffee said: Can you qualify this in terms of what you suggest as " a passive attenuator " as it certainly does not apply to other passive attenuators that can be used with cabling up to 6.5 metres. with perfect result. I've have a 10K stepped ladder attenuator and Autoformer. Long cables sound rolled off at both ends to me. I have purchased a LDR from you in the past but never tried it without a buffer. Link to comment Share on other sites More sharing options...
stereo coffee Posted August 1 Share Posted August 1 PM sent Link to comment Share on other sites More sharing options...
iz_thewiz Posted August 1 Author Share Posted August 1 8 hours ago, Cloth Ears said: What bookshelf speakers were you thinking of to replace the G2's? They're PFG as far as I'm concerned. What do you mean by PFG? If it was in my budget I would strongly consider Neumann or Dynaudio, but im now leaning towards Kali Audio. These are all studio monitors. Hi-Fi bookshelf I haven’t even started to consider the options, I guess it would depend on the stereo amp and it’s electrical compatibility. Link to comment Share on other sites More sharing options...
Cloth Ears Posted August 1 Share Posted August 1 12 hours ago, iz_thewiz said: What do you mean by PFG? If it was in my budget I would strongly consider Neumann or Dynaudio, but im now leaning towards Kali Audio. These are all studio monitors. Hi-Fi bookshelf I haven’t even started to consider the options, I guess it would depend on the stereo amp and it’s electrical compatibility. Pretty ? Good 1 Link to comment Share on other sites More sharing options...
iz_thewiz Posted August 1 Author Share Posted August 1 1 hour ago, Cloth Ears said: Pretty ? Good Haha. Not great, not terrible would be my review. They had poor manufacturing delivery on the overall construction of the boxes which led to an increase in power related noise over time. That was only the G2 series, I believe 3 and beyond fixed the issues. Link to comment Share on other sites More sharing options...
Cloth Ears Posted August 1 Share Posted August 1 My bad, I was thinking of the G4's - I don't think I know the G2's. My wife uses Mackies - but she only uses that for developing Spin classes and not for monitoring. I only have a pair of crappy AVE's, because I always listen on headphones (I think I turned them on in May). Without stopping your branching out, have you thought about just updating your monitors? The A series Adam Audio's are pretty good and the 7's are not super expensive (even new). I'll stop being off topic now. Hope you find your solution... 1 Link to comment Share on other sites More sharing options...
iz_thewiz Posted August 2 Author Share Posted August 2 3 hours ago, Cloth Ears said: Without stopping your branching out, have you thought about just updating your monitors? The A series Adam Audio's are pretty good and the 7's are not super expensive (even new). Absolutely. I'm planning on updating the near fields first then look into a dedicated hi-fi system (amp + speakers). The idea was to A/B each system which I can with the Coleman Audio unit. 1 Link to comment Share on other sites More sharing options...
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