AudioCircle
Audio/Video Gear and Systems => Enclosures => Topic started by: hilde45 on 13 Apr 2020, 02:47 pm
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Hi all,
I'm trying to figure out how to connect my REL 328 sub to the QS Preamp or Amp. The sub can connect to stereo amps in a few ways:
(a) high-level (a "Speakon" cable with three strands — Red-to-Right+, Yellow-to-Left+, Black-to-Right-negative);
(b) via a single low-level RCA-RCA cable;
(c) via single LFE RCA cable (but this is ruled out because I want to connect for audio listening not home theater).
The question regards how best to connect REL to QS monoblocks or QS preamp. Here's what I've learned:
(a) High level. REL says DON'T connect ALL 3 high level wires to speaker terminals (as one would with a stereo amp) because with monoblocks it will create a hum. However, if I do want to connect the two positive wires and ground the third elsewhere, where should I do that? On the preamp chassis? Some other way or place?
(b) Low level. If I try to connect the REL to the Preamp Out, I will need a Y cord to combine the Preamp stereo out to a mono input on the REL. But I've heard this will cause the monoblocks to become monaural, too. (Is that true?)
Comments on the above ideas? Other suggestions?
Thank you!
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Does your preamp have [ 2 ] outputs ? If so use IC to sub and IC to amps.
charles
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It does have two outputs. One already goes to Monoblocks and the other could go to sub, as you suggest.
As I mentioned this possibility in my OP, I said this: "I will need a Y cord to combine the Preamp stereo out to a mono input on the REL. But I've heard this will cause the monoblocks to become monaural, too. (Is that true?)"
Do you have a specific comment about that possibility? Thank you.
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snip....
(b) Low level. If I try to connect the REL to the Preamp Out, I will need a Y cord to combine the Preamp stereo out to a mono input on the REL. But I've heard this will cause the monoblocks to become monaural, too. (Is that true?)
snip...
Why would connecting your sub to a L / R pair of preamp outputs have any effect whatsoever on your main amps? :scratch:
I'm assuming your pre has 2 pair of variable outputs: one pair to the amps, one pair to the sub.
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Rel has guidance with respect to various subjects - i.e.
https://relsupport.zendesk.com/hc/en-us/articles/115004649108-Monoblocks-1-REL-Connection-Method
https://www.youtube.com/watch?v=3F5WTOu60hE
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The first 20 seconds this video says you cannot use high level to connect a single sub to mono amps. So your option (a) is eliminated.
https://relsupport.zendesk.com/hc/en-us/articles/115004649048-Stereo-Subs-Connection-Method
So you are left with only option (b):
https://relsupport.zendesk.com/hc/en-us/articles/115004649288-How-to-connect-your-REL-via-Low-Level-
If your sub has a pair of RCA inputs, simply connect a pair of IC from your preamp. If your preamp only has one pair RCA outputs, you need to buy splitters to send signal to both main amps and sub.
If your sub has a single RCA input, your need buy a "reverse splitter" (dunno the technical term) that combines the L /R preamp output into into a single input into the sub.
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Thanks for your replies.
Phil A. None of the REL videos or posts address this issue precisely enough. I've reviewed them.
Sunny daze. There is some debate about (a) -- if it's grounded on the chassis to avoid hum.
Re: (b) Good point about the variable. I need to check to see how it was wired, exactly. Just to review:
My question: "So, before I ordered the preamp, I had Mike wire the "Tape Out" as a *second* main out. Right now, the preamp's MAIN OUT goes to each monoblock and the other (TAPE OUT -- now a second main out) is free. An alternative is that I get a Y cable that will bring two RCA outputs from my Preamp into the single RCA input on the REL?"
Answer I received: "Don’t do that! It would result in the main speakers reproducing mono. And although I doubt that it would happen in this particular case, with some preamps doing that might even result in damage, eventually if not sooner, since you would be shorting the preamp’s outputs for the two channels together. Presumably the change that was made disconnected the two tape out connectors from the internal circuit points to which they are ordinarily connected, and connected them instead to the main out connectors (or to corresponding internal circuit points). So if you were to connect a y-adapter to the two tape out connectors, to create a mono signal for the sub by shorting the signals on the two tape out connectors together, you would also be shorting the signals on the main out connectors together. Thus an identical summed-to-mono signal would be provided to both monoblocks.
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So it sounds like your sub has only a single RCA input?
If so, I'm surely not technical enough to know if combining your 2nd set of variable outputs (the converted TAPE OUTS) and running them into a single sub RCA input results in a mono signal at your main amps.
If so, seems to me all you can do is:
(1) buy splitters to turn your preamp's main RCA outputs into 2 pair
(2) run one pair into your mono amps the normal way
(3) on the other pair, get a "reverse splitter" that combines the L and R into
one, and run it into the sub's single RCA input.
CAVEAT: unless doing (3) will also create a mono signal at main amps. Too confusing for me!!
A bit cumbersome, but there you have it. If there's another way, I'm not aware of it.
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The other solution is to:
(1) get another identical sub.
(2) use your preamp variable TAPE OUTS to drive the sub pair:
run the R i/c to one sub, and the L i/c to the other sub.
Need to research it to be sure, but I do believe that with a sub pair you can now run them high level with your mono amps. Dual subs simplify everything, and yields better sound in the process.
Alternatively, if you prefer a single sub, sell your current one and buy one with a pair of RCA inputs. Problem solved.
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Buy 2 REL subs at xxxx vs 1 at xxxx for stereo.
More better. :thumb:
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Thanks for the advice.
The whole issue derives from this REL having 1 RCA input and the fact of the monoblocks.
The possibility (not suggested by you folks!) that I cannot connect very good gear seems ludicrous. Surely there is a way.
Buying a second sub is not out of the question, but I'm trying to solve this problem, now.
I appreciate the suggestions.
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I have a situation were I have an all in one with no outs for the sub. I use a Jensen Iso-Max that connects to the amp speaker binding posts and gives you a XRL or RCA out, depending on te model, you might look into one for your situation. You would still need the y-splitter.
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Thanks. Good lead!
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(https://www.audiocircle.com/image.php?id=207209)
Stereo to mono adapter internet search.
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Thanks. Need to be sure that such a cable doesn't collapse the stereo field to mono.
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Not a cable; a box with 2 rca in 1 rca out.
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Gotcha. Something like this, I assume: https://www.newark.com/mcm-custom-audio/50-20795/stereo-to-mono-signal-converter/dp/25AC5154
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Yes, something like that.
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Confusion and conflicting opinions abound on this subject. Here's a thread that encapsulates it perfectly -- it looks like there is no black and white answer:
https://forum.audiogon.com/discussions/stereo-sub-out-to-mono-is-it-safe
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Confusion and conflicting opinions abound on this subject. Here's a thread that encapsulates it perfectly -- it looks like there is no black and white answer:
https://forum.audiogon.com/discussions/stereo-sub-out-to-mono-is-it-safe
If you think there is confusion why don't you try it and tell us how it works out. :wink:
The OP in that thread has an integrated with outputs labeled "sub".
:green:
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I saw that thread. I've heard from others that they actually harmed their Cary amp by trying to high-level wire it.
The reason I'm trying to pre-assess this question is to avoid damaging a new amplifier and/or a valuable sub.
I think the suggestion of the Y cable is or the little stereo to mono box is safe enough to try; experiments with speaker binding posts -- which are REL's preferred way of connecting subwoofers -- is less innocuous. Because I cannot get an answer (yet) from the amp maker, I'm waiting to hear from REL.
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If you think there is confusion why don't you try it and tell us how it works out. :wink:
The OP in that thread has an integrated with outputs labeled "sub".
:green:
It's the exact same situation. The guy in the AG thread has a 2nd pair of variable outputs, just like the OP here. Completely irrelevant that it is an integrated vs the QS line stage in this thread. Concept is exactly the same -- two pair of variable RCA outputs in both cases.
And why should I try anything? :scratch:
I don't have a connectivity problem. I have a preamp with 2 pair of variable outputs, and a pair of Gallo subs that are more flexible than the REL here. It allows me to use stereo or mono amps, one or two subs, high-level or low-level connections, without any bother at all.
Unlike the OP, my Gallos have a pair of RCA inputs for low-level connection, and 2 pair of binding post inputs for high-level amp connection. Matter of fact, the Gallo even has speaker outputs with a built-in high-pass filter sitting between the amp ins and outs. In this way I can run main amp into the sub and high-pass the main speakers. Makes them do less work, resulting in better sound.
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TOOBLUVR,
The outputs on the ATC integrated are specific for subs, so not the same thing.
Some HTRs and other pieces have 2 sub outs that are mono.
Did you even read any of the thread?
You can still try it and report back.
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The outputs on the ATC integrated are specific for subs, so not the same thing.
Some HTRs and other pieces have 2 sub outs that are mono.
Did you even read any of the thread?
I skimmed it.
He says his integrated has "L/R sub output". His exact words. Unless I'm missing something I understand this to mean that it's just plain old pair of normal active RCA outputs. No different that what's on a line stage with the 2nd pair of outs. They are designed to run either a sub or another amp for biamping. The signal is full range and stereo at these outputs.
It is not an LFE output, which is a single RCA connection that passes a previously processed signal (low passed and stereo combined to mono).
Unless my education is incomplete these are the only 2 ways that you can run signal to a sub using RCA connections. Is there something else I'm not aware of?
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Oh...OK....I got it...I think. :lol:
Are you saying the integrated's pair of L/R outputs are actually 2 individual LFE outputs....designed to run 2 separate subs?
If not....I'm really lost! :o
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And with that said, I'll bow out now. I obviously don't know what I'm talking about! :lol:
I always found this sub connection stuff very confusing......
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Wait...wait ....wait!
He specifically says they are L and R output.......and asks if he should combine them for his sub's "mono input".
If it was already processed LFE outputs he would not be saying that, nor asking the question. He would simply take one integrated output (processed for sub) and run it into one sub LFE input. He would not be seeking to combine them.
So I return to my original post.
Sorry for the hijack!
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On the ATC they are summed mono outputs specifically for subs even though they are labeled as L & R.
Back to the OP question here, not a good idea to combine L & R with a Y cable on his preamp for a mono sub input.
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Here is REL's response: "We would recommend connecting low level from your preamp to the R328 as the safest connection for your current setup. As long as it's safe to use a Y splitter out of the QS preamp, this will be fine for going into the single input on the sub."
So now I need to go back to Quicksilver (QS) to ask that question. Jeebus.
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Update from Quicksilver: "I would connect the ground wire to the right channel amp ground just as they [I believe I quoted Almarg] suggest. If there is a hum then you might have to connect the woofer to just one channel that is disconnect the left + wire. A Y connector will mono the outputs on the preamp."
Update from me: I tried the high level. Connected to both mono blocks. No hum. Works fine. (Will it last?)
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:thumb:
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I'm liking your handle because I find myself "openly baffled." (And not a little red in the face for introducing this topic. Yet the data seemed all over the place from different people.)
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Now I may be confused by now, but I believe you said the preamp's rca outputs were modified to have one main out and one tape out. It that's the case the tape out is NOT variable and will not work to hook up a sub. If the second output is simply labeled tape and nothing was actually modified you simply use the low level outputs to the rca inputs of the sub. To use high level inputs on the sub you need two sets of speaker cables, one to the sub from the monoblocks and then a set from the sub to the speakers. This uses the internal crossover of the sub to take some of the bass load off of the speakers.
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The preamp's rca outputs were modified add a second main out. (What was labeled "tape out" is now the second "main out.") And you're right — just as stated by the QS manufacturer — that tape out will not work to hook up a sub because that's a stereo out and the sub only has a mono input. A Y cable will collapse the stereo field of the other RCA main output to the main speakers.
That said, another way of combining stereo to mono, via a small device, would work. That is a possibility. I want to avoid that, however, because the low-level connection is inferior to high-level, sonically.
But it's all good — I have connected things with REL's high-level connector; this is with the blessing of the amp manufacturer and with no hum on test.
I don't follow the rest of your reply (mentioning two sets of speaker cables), because the sub only has a high level cable which terminates in their Speakon connector port at the sub and sends three wires out to the amplifier's speaker terminals — red, yellow, black.
Speakon: http://signalcable.com/images/RelSpeakon.jpg
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On the ATC they are summed mono outputs specifically for subs even though they are labeled as L & R.
Back to the OP question here, not a good idea to combine L & R with a Y cable on his preamp for a mono sub input.
http://www.faqs.org/faqs/car-audio/part4/
5.16 How do I turn a stereo signal into a mono signal [BW]
=================================================================
Creating a mono signal is often necessary when you are powering a
subwoofer by bridging the amplifier. Many people do not realize that
bridging an amplifier does not always provide a mono signal - many
amplifiers will simply use only one input channel, which means that the
subwoofer won't be receiving the full signal.
Some amplifiers have a switch that will allow you to combine the left
and right channels into a mono signal. Some signal processors and head
units provide a subwoofer-out channel that can be switched between
stereo and mono.
If you don't have this feature on any of your equipment, you will need
to provide a mono signal to the amplifier. The common thought is to use
a Y-adapter to "combine" the left and right channels. However, by
using a Y-adapter, you are actually summing the line voltages and
directly shorting the left and right channels at the head unit, which
could cause problems.
The correct way to create a mono signal is to cut off the ends of the
RCA cables, combine the signal grounds (the outer shield), and then use
a 1 kOhm (1/4 watt, 5% tolerance) resistor to each of the center
conductors. Solder and insulate the resistors so that you don't short
them prematurely, and then connect the two resistors together. Connect
the summed signal ground to the shield of the new RCA plug, and the
summed center conductor to the center pin of the RCA plug.
I always refer to this whenever the discussion of combining RCA signals comes up. It's car audio, but it's the same principal. As long as you have that 1/4 watt resister on the center pins, everything is good. I built and still have a summing circuit I built long time ago. I used a radio Shack project box, multi-RCA panel, resisters, and some wire. I had it set up where the two middle pairs were stereo and the two outer pairs were summed. It's weird but I can never miss-connect anything. Stereo in, stereo out, and four mono connections. Plus, I don't like destroying functional RCA cables.
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Thank you!
I saw a couple solutions already made:
Simple stereo to mono device: https://tinyurl.com/w4p5dxf
More complex, programmable device: https://tinyurl.com/rjaxcxq
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snip
I don't follow the rest of your reply (mentioning two sets of speaker cables), because the sub only has a high level cable which terminates in their Speakon connector port at the sub and sends three wires out to the amplifier's speaker terminals — red, yellow, black.
Speakon: http://signalcable.com/images/RelSpeakon.jpg
He was just talking general concept = speaker cable from amp to sub for high level connection.
This is how I connect my sub.
REL does the exact same thing, they just use their own proprietary cable / connector.
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Thanks -- that helps. I'm limited to what the back of my REL gives me, so I wasn't following. Appreciate the clarification and I now get the general (and helpful) point.
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Here is REL's response: "We would recommend connecting low level from your preamp to the R328 as the safest connection for your current setup. As long as it's safe to use a Y splitter out of the QS preamp, this will be fine for going into the single input on the sub."
So now I need to go back to Quicksilver (QS) to ask that question. Jeebus.
I would distrust REL from now on. They are an established audio manufacturer, and they are recommending a ghetto method for using their products.
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I would distrust REL from now on. They are an established audio manufacturer, and they are recommending a ghetto method for using their products.
Maybe they had limited staff and no tech when this REL person gave a bad answer in the reply. :dunno:
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Maybe they had limited staff and no tech when this REL person gave a bad answer in the reply. :dunno:
Bad advise is still bad advice. Are they going to fix your pre-amp if it gets damaged?
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http://www.faqs.org/faqs/car-audio/part4/
I always refer to this whenever the discussion of combining RCA signals comes up. It's car audio, but it's the same principal. As long as you have that 1/4 watt resister on the center pins, everything is good. I built and still have a summing circuit I built long time ago. I used a radio Shack project box, multi-RCA panel, resisters, and some wire. I had it set up where the two middle pairs were stereo and the two outer pairs were summed. It's weird but I can never miss-connect anything. Stereo in, stereo out, and four mono connections. Plus, I don't like destroying functional RCA cables.
The DIY crowd I know said use 10K ohm resistance or more. There was also a mention of using OP-amps.
https://www.electronics-notes.com/articles/analogue_circuits/operational-amplifier-op-amp/virtual-earth-mixer-summing-amplifier.php
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REL followed up, both with a clarification and the willingness to reach out to my amp manufacturer. And with the offer to talk on the phone, and a phone number.
I think they've been impressive every time I've dealt with them and this is one-off -- and they're sticking it out to make it right.
And also: I bought their product used and still, they're helping.
Full confidence in REL.
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REL followed up, both with a clarification and the willingness to reach out to my amp manufacturer. And with the offer to talk on the phone, and a phone number.
I think they've been impressive every time I've dealt with them and this is one-off -- and they're sticking it out to make it right.
And also: I bought their product used and still, they're helping.
Full confidence in REL.
8)
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Excellent.