Proprius with a subwoofer.
Printed From: Graham Slee Hifi System Components
Category: And the rest
Forum Name: Amplification
Forum Description: Share your interests or views on amplifiers, preamps, etc
URL: https://www.hifisystemcomponents.com/forum/forum_posts.asp?TID=2573
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Topic: Proprius with a subwoofer.
Posted By: Gary
Subject: Proprius with a subwoofer.
Date Posted: 29 May 2015 at 5:31pm
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I've had a Majestic and Proprius system for a while now and would like to connect a subwoofer. The plan was to use a Dspeaker Antimode unit to manage the subwoofer this requires line level input for left and right, is it possible to use a speaker level to line level converter cable? I've seen a few about that consist of wires that connect to the speaker terminals and then to a RCA phono plug, with a resistor network in between. Has anyone used this method and if so did it have any effect on the amplifier they were connected to? Thanks ------------- Solo ULDE, CuSat50, Spatia Links |
Replies:
Posted By: BAK
Date Posted: 29 May 2015 at 9:47pm
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Graham, Wouldn't the "Fixed line-level stereo analogue outputs" be usable for this ? Gary, do you need the "required line level input for left and right" to be controlled by the Majestic volume control? Are you using balanced cables from the Majestic DAC to the Proprius amps? If so, the fixed line level RCA jacks should be available. Speaker level adaptation to line level is always inferior to a direct line level; poor frequency response, added distortion, limited range for level corrections. ------------- Bruce AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way! |
Posted By: Gary
Date Posted: 29 May 2015 at 9:59pm
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The line level in to the subwoofer does need to be volume controlled. I am using balanced connections from Majestic to Proprius and a Solo ULDE is using the fixed line out. ------------- Solo ULDE, CuSat50, Spatia Links |
Posted By: BAK
Date Posted: 30 May 2015 at 5:33pm
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Hi Gary, Are you playing music through the Proprius amps and speakers at the same time as listening to your headphones? Maybe Graham knows if the Balanced Outputs can be "Y" connected to the Proprius and a Balanced-to-RCA converter, solid state type (a transformer type would not be good for bass response). Otherwise, it may be best to have the fixed line level RCA jacks on your Majestic DAC converted to be controlled by the volume control. (This would of course defeat the SOLO headphone use as is.) For situations like these, a balanced input converter unit with 1 balanced output and 1 single-ended output would work. It would connect the Majestic DAC balanced outputs to: the Proprius balanced inputs and the "required line level input for left and right" RCA inputs for your sub-woofer. Balanced converters are available. Graham, here is that balanced conversion problem again.  ------------- Bruce AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way! |
Posted By: Gary
Date Posted: 30 May 2015 at 7:47pm
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I don't want to make any changes to my Majestic or add any converters in the signal path between the Majestic and Proprius, they sound very good as they are and I don't want to compromise them. I don't see any problem in using speaker to line level converters as that's what most subwoofer manufacturers use anyway, the resistor network is part of the amplifier plate. I just wanted an okay to say the Proprius will be fine. My subwoofer has a speaker level input but uses three wires to connect (+right, +left and -left or right) this is a problem for mono block amplifiers. ------------- Solo ULDE, CuSat50, Spatia Links |
Posted By: BAK
Date Posted: 30 May 2015 at 8:08pm
This is a speaker level-to-line-input-level built into the sub-woofer "plate amplifier". One would connect a + and - speaker wire (speaker wire only) from each channel's output to the sub-woofer "plate amplifier" input. This should work provided the Proprius amplifiers have a common output ground, not floating (common minus connection). Come to think of it, the same would be true for a resistor divider connected to the Proprius amplifiers' outputs... again the Proprius amplifiers would have to have a common output ground, not floating. Only Graham can say if the minus speaker terminals on 2 Proprius amplifiers can be connected / shorted together. ------------- Bruce AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way! |
Gary wrote:Posted By: Ash
Date Posted: 30 May 2015 at 8:48pm
When I drove some high impedance headphones from a pair of Proprius, I shorted the black terminal of each together as the female jack plug I used to connect the headphone has a common ground. Luckily I didn't have any trouble with doing this but in some applications, I guess it could cause problems such a ground loop hum???
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Posted By: Graham Slee
Date Posted: 31 May 2015 at 10:10am
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@Gary. You should be able to join the two black terminals without any problem, but I've not tried it myself. The black terminals are at chassis ground (0V) potential. The thing you should try not to do is short a red to a black... however, after the kit's last outing I hurriedly put the Proprius back on the shelf and plugged in the bi-wired cables, spun a record and couldn't hear anything. So I checked I'd turned up the volumes on the Majestic as well as the pair of Proprius. Then I checked all the interconnects and switches on the Majestic and couldn't find a fault. The record deck was still playing merrily away, so I selected a digital input and nothing came through the speakers either... I then realised I'd made a tragic error! I'd been experienting with using one Spatia as send and the other as return. A black and a red to one Proprius terminal and the other black and a red to the other Proprius terminal - same at the speaker end... What I'd hurriedly done was to plug the two reds to the red terminals and the two blacks to the black terminal... Got it yet? Yes, I was playing into a dead short! For somewhere in the region of ten minutes. "Oh dear", I thought. So, I corrected that silly miswire on the fly without turning anything off or turning the volume down, and I had music again. I listened intently for a good hour to hear if their was any distortion, thinking I could have damaged them, but I couldn't hear any. The amps weren't running hot, so it looked like they survived fuses still intact. They were designed to do that, but I don't advise anybody doing it to prove the point. ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: BAK
Date Posted: 31 May 2015 at 1:14pm
With Graham's confirmation today, use your "built in" speaker-level-to-line-input-level connections on the sub-woofer "plate amplifier". Be careful of your polarities as even I  (and those more experienced) can miss a plus and minus or plus and plus crossed connection.RULE OF THUMB: always double check speaker-to-amplifier connections. Suggestion: Plug both Proprius power amps into the same AC power source as the sub-woofer "plate amplifier". This will reduce any source of noise or hum. AND, run the speaker wire only from the Proprius amps' outputs directly to the "plate amplifier" input, keeping these wires 3 foot away from all AC power cables. If the input to the "plate amplifier" seems to be too loud (input level control set way low) you can put a 4 ohm, 10 watt resistor in series with each plus connection. This will also lessen the load on the Proprius amps' outputs (and giving cleaner sound to the speakers). Here to help, ------------- Bruce AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way! |
Posted By: Gary
Date Posted: 31 May 2015 at 2:29pm
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Thanks Graham. Only worry I've got now is if my subwoofer is up to partnering a Majestic, pair of Proprius and PMC twenty 23s. ------------- Solo ULDE, CuSat50, Spatia Links |
Posted By: discrete badger
Date Posted: 31 May 2015 at 3:39pm
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On line-level subwoofer hum.... I followed Graham's advice (from an old posting or blog somewhere) and used coaxial satellite cable to make up a single-channel connection. The hum completely vanished and the SQ is great. Thanks Graham.
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Posted By: Fatmangolf
Date Posted: 31 May 2015 at 9:26pm
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Apologies for my late arrival in this thread. I run 2 REL Q-series subwoofers off the output of my Proprius amps and this setup works fine as it has with my previous amplifiers. Each cable connects both red terminals and one black terminal to the high level input of the sub. Assuming 'plate amplifier' means the electronics inside the subwoofer I am fairly sure the input impedance of the sub will be much higher than that of a speaker, probably 10k or more and it will include attenuation to match the levels as well as the low pass filtering to blend the sub with the main speakers. If you need to attenuate the signal get a resistor of about the same value as the sub's input impedance, that should be in the spec sheet/manual. Those two subs are also connected to my AVR using phono cables into the low level inputs. I would second Graham's advice about using a decent cable like satellite coax for this. ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
Posted By: Fatmangolf
Date Posted: 31 May 2015 at 9:28pm
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Graham, I knew the Proprius amps were very well engineered but that is remarkable. How many other amps on the market would take that punishment and still sound great? ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
Posted By: BAK
Date Posted: 01 Jun 2015 at 2:45pm
Gary and Jon, My thoughts were that a coaxial cable might add too much capacitance to the speaker load of the Proprius amps. I stand corrected if others have used coaxial cables without any adverse effects. Satellite coax does have a very low capacitance. I have seen some sub-woofer 'plate amplifiers' with a dummy load on the input of 4 to 16 ohms before the speaker-to-line-level conversion attenuator. I agree with Jon's recommendation " to attenuate the signal get a resistor of about the same value as the sub's input impedance, that should be in the spec sheet/manual". I have noticed the speaker industry calling an amplifier that is mounted on a "plate" or panel on the back of the sub-woofer cabinet a "plate amplifier". I bow to those who have used sub-woofer "plate amplifiers", they have their uses for some. I am of the other school of thought that uses a 2 channel stereo amplifier driving just 2 speakers, the bass and all other frequencies being delivered by the same 2 speaker systems. Gary, I hope you find the sound you wish to hear. Jon, I am glad you chimed in. I would not want to steer any one off track Your "hands-on experience" is much appreciated. Graham, you do have a GEM of a design in these Proprius amplifiers. ------------- Bruce AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way! |
Posted By: Fatmangolf
Date Posted: 01 Jun 2015 at 6:04pm
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I see your point Bruce about proper stereo 2.0 rather than 2.1. I must confess that my subs aren't connected at the moment as I unplugged them before fine tuning the GX300 (floor standing) speaker positioning at the weekend. Although I miss the lowest bass, it is less of an issue than when I had the stand mounted GX100's at the front. On the cabling types for sub connections, it may help to clarify my language: High level = speaker connection so something resembling speaker cable should be fine to connect the amp to the subwoofer. I wouldn't use a screened cable for the loading reasons you pointed out, even coax. Low level = line level connection from AV amp and a good quality screened cable should be used that includes a low resistance ground path IMO. And you are right about the sublime Proprius amps! ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
Posted By: BAK
Date Posted: 01 Jun 2015 at 9:04pm
Jon, given your clarification, I believe the connection "discrete badger" and Gary are talking about is high level (directly from the Proprius speaker terminals). It may be fine after all to use very low capacitance coaxial cable to connect directly from the Proprius speaker terminals to a high level input on a sub-woofer "plate amplifier". Note: Most power amplifiers have an internal 0.1 uF capacitor directly across the speaker terminals in a filter network to compensate for the inductive characteristic of voice coil dynamic speakers. [My 60 watt RMS power amplifier has a 0.1 uF capacitor in series with a 10 ohm resistor in this filter network... others have a 0.1 uF capacitor in series with a 4 ohm resistor in this filter network, and others a 8 ohm resistor.] A very low capacitance coaxial cable of moderate length should not add too much capacitance. Here the added external capacitance to the speaker terminals from using coax must be kept very low to not upset the output filter network. At low value impedances of 4 to 16 ohms, it would take some added external capacitance without any problem, as long as there is a 4 to 16 ohm load...IOW, as long as the speakers are connected. Again; RULE OF THUMB: always double check speaker-to-amplifier connections.  Before the AC power is applied. ------------- Bruce AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way! |
Posted By: Graham Slee
Date Posted: 01 Jun 2015 at 11:21pm
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The phase and gain margin on the Proprius is generous so cable capacitance isn't a big deal for it. The series RC filter inside power amps is called a Zobel network which is designed to compensate for load capacitance within a small bandwidth and preserve stability. Of greater importance is the use of an output inductor. Most amp designs I've seen use a few turns of wire around a "damping" resistor, and most of these simply aren't effective. It is quite difficult to guesstimate what value is going to do the most good because there are so many parasitics that the "sliderule" answers of old tend not to work. By modelling in parasitic parameters into a schematic, SPICE modelling reveals quite a lot, and the inductor and damping resistor values can be found - often a lot larger than one would think. The output inductor on the Proprius is a network of components designed to offset parasitics over different frequency ranges and to not compromise the sound. From the model's point of view capacitance up to 50,000pf with a load of 10k has no effect on stability. Open-loop gain also has a bearing on stability - large amounts of negative feedback can often lead to oscillation because the negative feedback becomes positive under certain loading conditions. The Proprius can run without its negative feedback loop and only 18dB of negative feedback is applied by the loop - very much like tube amps. So please feel free to try what you like (within reason). However, low capacitance close spaced conductors have low magnetic and electrical fields which are good for low EMC emissions and immunity, and that guards against RF interference, and any amplifier so assisted is going to perform better, so low capacitance slow/tight twist or coax cable is best. High capacitance cables and wide spaced conductors invite RF because of their large magnetic and electrical fields and make a big difference to how an amp can sound - basically by driving it into its unstable operating area. You can get a huge soundstage - completely unnatural but very impressive - and this is often considered an improvement (by the easily led). Many a well-known amplifier has fried using such cabling. Such amplifiers don't use output inductors... ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: CageyH
Date Posted: 19 Oct 2015 at 4:56pm
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I am about to connect my MJ Acoustics Pro 50 sub to my system, as my little Frugel horns could do with a bit of help low down (when the wife is out). The RCA output is taken by the AV amp, so I am looking at taking a feed from one of the Proprius using speaker cable, to a Speakon high level connector on the plate amp of the sub. Does this sound sensible? It is for occasional use only, and if I like it, I may get a bigger/better sub later. I just want to check before I do anything daft to my system. ------------- Kevin European loan coordinator, based near Toulouse, France. Funkified SL1200 Mk.II, BB3, Firebottle Kin , ADI-2 DAC FS, Modulus 686, PD-S703, Solo UL, Triangle Antal EZ |
Posted By: CageyH
Date Posted: 19 Oct 2015 at 5:19pm
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Manufacturers instructions: You connect the 3 bare end wires of the Neutrik Speakon cable alongside your existing speaker cables on the back of your amp as follows: RED to left + (positive) YELLOW to right + (positive) BLACK to ONE of the - (negatives) NOT BOTH. This is the most common connection for stereo amplifier users who do not have a dedicated sub output and wish to extend the bandwidth and add a new depth dimension to their existing speakers. So I guess I am going to have to make up a cable to take the feeds from both speakers, to the sub. What a pain... ------------- Kevin European loan coordinator, based near Toulouse, France. Funkified SL1200 Mk.II, BB3, Firebottle Kin , ADI-2 DAC FS, Modulus 686, PD-S703, Solo UL, Triangle Antal EZ |
Posted By: Gary
Date Posted: 19 Oct 2015 at 7:23pm
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I did manage to connect my old BK XLS300 up to my pair of Proprius, as suggested earlier by Graham, by connecting red to right +, yellow to left + and black to both left and right -. Everything worked fine but it highlighted the deficiencies of the sub so now I'm using a B&W PV1D and all is well. It's not the deepest sub but it's definitely musical. ------------- Solo ULDE, CuSat50, Spatia Links |
Posted By: Mikeh
Date Posted: 18 Oct 2021 at 10:36am
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Resurrecting this old thread as I've been referring to the advice while testing a REL subwoofer with my Proprius. The instructions from REL for the current Tx series are quite specific, for mono bloc amps there should be one sub per amp and for 'differential' ( balanced to my understanding) mono blocs the high level connection is very different. In this case for the Proprius, both + ive (red and yellow) wires in the Speakon cable should be connected to the + ive mono bloc output, with the -ive (black) wire in the Speakon cable floating (not connected to anything). I found this works, however the input to the REL is such that it's gain is only 2-3 clicks off minimum. Removing one of the Speakon +ive wires results in hum. So to reduce the input to the REL I've added a 4 ohm/ 10 watt resistor in series ( as suggested above). The end result is very good with just the one sub on trial so I'm going ahead with purchase of a pair. I just wanted to check if anyone else has experienced the same connectivity issues with REL subs. Advice would be appreciated. ------------- Mike Technics sl1210g with Victor U-2 or Technics EPC-205C mk4 Accession MM, Majestic + Proprius, Solo ULDE Innuos Zen mini mk3 streamer Harbeth P3ESR XD paired with 2x REL t5x |
Posted By: discrete badger
Date Posted: 18 Oct 2021 at 5:36pm
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In a word - yes. Resolved by also having a low-level (RCA) connector to my home cinema amp. (RELs offer the possibility of dual simultanous connection so that sub can effectively do two roles - low pass for high level speaker connection and unfiltered for LFE effects in home cinema). REL recommend borrowing the home cinema amp's ground for this purpose. For me this provided an adequate ground reference for the REL. So then the yellow/red potentials don't actually "float". But you may not have a home cinema setup, so ... Unplugging the low-level connector produced horrible hum. So I connected the black wire to the 0v output of one of my amps (not Proprius). I also tried chassis ground (i.e. turntable ground terminal) and that also worked fine. I think with this "don't connect the black wire" advice, REL are worried about two things, neither of which I believe apply to the Proprius. 1. That the "-ve" terminal is not actually locked to 0v, but actually moves around just as much as the "+ve" terminal, but at the opposite polarity. This is the case with a balanced output stage, which the Proprius doesn't have, only a balanced input stage. So you can connect the black wire to the "-ve" terminal of either Proprius because it's a 0v ground. 2. That many PWM switcher amps reference their "-ve" to actually "+10v" or thereabouts and the "+ve" terminal moves around relative to this. The Proprius isn't a switcher so its -ve terminal will actually be at 0v, so this doesn't apply either. But - bigger picture! For a pair of (presumably identical) subwoofers you have the golden opportunity of subwoofer stereo. If that works for your room layout, then why not forget all the above and just wire red+yellow to speaker +ve, black to speaker -ve on each side, one subwoofer exclusively per speaker. The result should be superior.
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Posted By: Mikeh
Date Posted: 18 Oct 2021 at 6:09pm
Thanks for the information.
My intention is to install one sub per Proprius. Whenever I tried connecting the Speakon black wire to Proprius -ive ground the hum returned. I did try connecting a RCA cable between a spare Majestic port and the REL low input to provide a ground but this did not remove the hum. Only with the two Speakon +ives to Proprius +ive gives a connection without hum. Which I don't understand but I guess just have to go with. ------------- Mike Technics sl1210g with Victor U-2 or Technics EPC-205C mk4 Accession MM, Majestic + Proprius, Solo ULDE Innuos Zen mini mk3 streamer Harbeth P3ESR XD paired with 2x REL t5x |
Posted By: discrete badger
Date Posted: 18 Oct 2021 at 7:27pm
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I think what's happening there is the unconnected yellow is free to float and pick up hum from some source close to the cable. Connecting it to amp +ve effectively pins it to 0v (which it will be when playing no signal, when you're listening for hum) and removes the hum. The REL amp sums L and R signals relative to ground, so on paper you could try connecting it to amp -ve! That should halve the REL output. I just tried it on one of mine (an older REL). When I disconnected the yellow from the amplifier +ve, hum appeared. When I connected it to amplifier -ve, hum disappeared and half output.
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Posted By: Mikeh
Date Posted: 18 Oct 2021 at 8:31pm
That's interesting. I'll give it a try. Just seems so wrong to connect +ive Speakon wire to -ive Proprius but if I works and your's hasn't blown up (!) it would remove the need for a resistor and simplifying installation. Thanks! ------------- Mike Technics sl1210g with Victor U-2 or Technics EPC-205C mk4 Accession MM, Majestic + Proprius, Solo ULDE Innuos Zen mini mk3 streamer Harbeth P3ESR XD paired with 2x REL t5x |
Posted By: discrete badger
Date Posted: 18 Oct 2021 at 9:23pm
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Feels weird I know! But if it helps, imagine what happens with black wire on 0v (speaker -ve), yellow wire on left +ve, red wire on right +ve. Now imagine music on right channel only, and silence on left channel (perhaps via the balance control) Normal REL-advised connection scheme. Normal signal conditions. Subwoofer won't explode, but play right channel bass only. Yet yellow wire is at 0v potential, same as if it were connected to speaker -ve!
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Posted By: Fatmangolf
Date Posted: 18 Oct 2021 at 10:21pm
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Great example of a real world solution. ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
Posted By: Mikeh
Date Posted: 19 Oct 2021 at 5:27pm
Tried your suggested connections to new RELs and it works a treat, halving the input to sub gives its amp more chance to warm up. Straight out of the box they aren't very subtle but after proper break in period and setting up I suspect there will be significant improvement. Thanks for the support  ------------- Mike Technics sl1210g with Victor U-2 or Technics EPC-205C mk4 Accession MM, Majestic + Proprius, Solo ULDE Innuos Zen mini mk3 streamer Harbeth P3ESR XD paired with 2x REL t5x |
Posted By: discrete badger
Date Posted: 19 Oct 2021 at 9:38pm
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Great news! Happy to help! And good to have further evidence of the Proprius's compatibility with REL's 3-wire connection, despite REL's general concerns with monoblock amplifiers. My current amps are dual stereos bridged to mono - one of the cases that REL's advice is most concerned with, because of the way the bridging is implemented. In this mode you connect speaker +ve to right amp +ve and speaker -ve to left amp +ve (!), and the left channel plays the inverse of the right. There is no speaker connection to the amp -ve terminals, which stay at 0v. This also works absolutely fine with the 3-wire connection for a single REL, provided that the black wire goes to 0v (either left or right amp -ve of either amp, so basically any black-coloured speaker terminal). Connecting it to the same -ve that the speakers see would be a potentially damaging error, because it isn't 0v in this configuration.
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