@lak Thanks for the suggestions. It's because I watched all those videos but did not see an answer to my question that I didn't find them helpful enough. @almarg Regarding the primary suggestion you made, connecting the REL's speaker-level inputs to both monoblock amps and then grounding it on the PREamp, do you have a suggestion how to ground it? There is no dedicated ground on the Preamp -- e.g. no phono ground (because no phono stage). Here's a photo: http://quicksilveraudio.com/wp-content/uploads/2017/07/12-1024x293.jpgJust back off on a chassis screw and put the small wire around it? |
Thanks so much. Sounds like a good plan B. |
@pjr801 — the reason is because the standard advice for this REL is to connect it to the main speaker terminals on a normal (non-monoblock) amp. I am trying to follow that advice from REL but adapting it to monoblocks.
@almarg Thanks! I feel confident about these purchases.
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. Does that fact change your advice? (I don't know why the main speakers would become mono by doing this, but that's just from lack of general understanding about how these are wired.)
Depending on what you say to the above question, I'll try the monoblock connection approach you suggest — and just listen for a hum. I'll also contact REL. It would be shame if I couldn't use the sub.
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Thanks imhififan -- I'll definitely keep that in mind if the high level input solution won't work. |
@almarg FYI, I just found old threads where you were discussing exactly this problem. I wrote to Quicksilver, but don’t have a clear answer (yet) about how my preamp is wired (for the low-level RCA stereo to mono fix) or how best to ground a high level connection (the Speakon cable approach). I got a very brief reply, but it didn’t answer the question. I also wrote to REL, to see what they say. I’ll try to relay what they say.
I am a little concerned that the high-level rig-up you suggest might feed back to my amp and cause a problem. It's a new amp and I'd hate to immediately hurt it!
The adapter mentioned above by @imhififan would be attractive if I knew it was not going to collapse the stereo field on the mains. I suppose that’s the point of that solution, but I’d like to know before I waste $50 or so! |
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."
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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."
I will comment that I tried an RCA out from my Streamer and while I could hear bass, it was definitely inferior to the high level connection.
@jl35 When you say "I do use the upgrade REL cable" you mean the "Speakon" cable that clicks into the sub and has 3 wires on the other end? I assume so but these subs can differ.
Also JL35 (and Almarg) -- are you at all worried about some kind of damage happening to the amps? @decooney mentioned this happened to him with a Cary amp years ago.
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@imhififan I am so very glad to have this forum. I have no idea why they gave me this advice.
The advice you gave -- the converter box -- would NOT cause the issue of the Y cable though. Is that right? (I know you recommended it but I want to make sure that I gave you a complete enough picture at that point.)
What a headache. |
Update from me: I tried the high level. Connected to both mono blocks. No hum. Works fine. (Will it last?) |
@almarg
Connections, Subwoofer speakon connectors to monoblocks:
Red to Right +
Black to Right -
Yellow to Left +
Regarding outputs that are "balanced or bridged" I don't know how to tell — but if it's indicative, there are only RCA connectors on the preamp's outs and they run to RCA inputs on the amps.
Interesting point about the un-connected approach to the black ground wire. If I heard a hum, I suppose I could try disconnecting that wire.
I appreciate your taking a look at the mono/stereo device mentioned by imhififan. In some ways, it still seems like the safest way to go, but I can testify that I tried both high level and low level inputs tonight, and high level is far superior and it's drawing on exactly the signal being sent to the speakers.
I continue to admire the clarity and concision of your replies, and the time you take to research someone else's (my!) question. Thank you. |
@almarg Great to hear. I certainly want to avoid any issues. I *assume* that if I start to hear a hum that I’ll just disconnect the setup. I asked QS in several emails about grounding to preamp chassis and that suggestion wasn’t even taken up in the (very sparse) replies. @daveyf Is that set up the one suggested by REL? Not for monoblocks. If you look back at some of the REL links people shared above, you’ll see that REL suggests NOT connecting the sub's high level connector to monoblocks. They recommend using the "low-level" input. My problem (as described above) is that my preamp output is stereo and the REL I own only has a single RCA input. My sense is that the advice they’re giving here is somewhat inexpert and/or poorly researched. I am not confident that my question got to someone with sufficient knowledge and/or they didn’t really stop and think hard about the question. Their suggestion of a Y cable would (as QS, almarg, told me) collapse the stereo field for the main speakers. While I sympathize with REL’s predicament of having many customers with a wide variety of products, it would be better to say "we’re working on your question" than to give erroneous advice. I used that exact set up on my prior ARC stereo tube amp, and it worked fine. I also use that basic set up on my ss balanced stereo amp. I’m assuming by "same set up" you’re saying that you used the high level REL connector. The issues raised by my situation are critically different, insofar as they pertain to grounding the subwoofer’s connection on two separate monoblocks. |
@djones51 -- Interesting. Just reading the manual. "3.8 MONO/STEREO MODE The 2 Way Advanced 21 plugin supports mixing of two output channels, allowing this plugin to be used in “2.1”
applications where a mono subwoofer signal is derived from a stereo signal. To access this selection, click on the
System Settings tab." |
@djones51 -- Thanks. That may be helpful.
@jl35 Agreed. I got this $1800 sub used for $900 because it just wasn’t in my budget to spend more. It’s now hard to find. I might sell it and get two lesser subs (maybe smaller REL’s). But for my present room, this single REL is definitely powerful enough, though as you and others have pointed out, it’s not optimal. |
@jl35 Got you. And that makes me feel good! Since I just got these amps, I will have a chance to live with the setup for a while and see how itis.
@daveyf That's a really interesting point -- two smaller subs. I read somewhere not to go smaller than a 10 inch woofer. I wonder if that's for any and all subs or for just one. And I don't blame REL for their advice -- it does seem optimal for sound and that's what they're known for. It is helpful to have some "escape hatch" for that person who wants/can afford *one* good sub rather than *two* lesser subs.
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Thanks, daveyf. I can't remember where I read that it should be at least 10, but my space is only about 500 sq feet so I bet your setup would work well. I'm sure we could start a shooting match over in "Speakers" if we tried...let's not. |
@ieales I appreciate your input and will look at the links. There are now a lot of different opinions out there. The amp mfr says it’s fine. REL prefers high level to their own sub if there are two subs. Otherwise, they say low level but have no answer as to how to sum the stereo signal to mono. Others on this thread say both. Can you clarify what you meant by "Their" when you said: you should NEVER use the high level output. Especially on a tube amp. Their use is strictly lofi. Thanks. |
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