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Couple of ? Regarding RCA connection to XLS amps


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#1 Rhed

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Posted 08 May 2014 - 03:15 AM

Hello.. I'm new in this forum. Been reading up on consumer to pro gear set ups. As this will be my first with pro amps. I have speakers that are 4 ohm rated that's on order. Anyway I had a couple question in regards to connecting RCA (unbalanced) to XLS amps. I'm looking into getting 3 XLS2000 to run my LCR in my HT. Each in bridge mode. Now my receivers pre outs are only RCA. And outputs 1.5Vrms. But I wanted to rack the amps in the next room over. So the RCA cables will be about 15-20 ft to the next room. Will this be OK? Or should I just go Unbalanced>active converter>balance outs>XLS amp? Thanks...


#2 Deromax

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Posted 08 May 2014 - 11:31 AM

I think a good, well shielded RCA cable will be OK at that distance.  Actually, I have done more distance than that with no issue.  Such a cable will be thick and somewhat less flexible.  Look for "double shileded", "100% shield" or such.

#3 dakos

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Posted 08 May 2014 - 12:28 PM

XLR cables are much better in carrying the signal to longer distances and also in an electrically noisy environment, since you're going to use a Balanced/Unbalanced converter anyway, the way to go is Unbalanced Receiver-> Unbalanced/Balanced converter via short RCA cables->Pro Audio Amp via long balanced XLR.

Not that I have any problem answering your questions but have you seen this forum:
http://www.hometheatershack.com/
??

One bridged XLS2000 into each speaker sounds allot even for home audio speakers with their low sensitivity, what speakers do you have or plan on buying?
Avi

#4 Rhed

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Posted 08 May 2014 - 05:54 PM

^^ I have three of these on order for my LCR. Btw, I will have the amps on a dedicated 20 amp circuit. Im not going to use all that power. Its mainly headroom.
http://jtrspeakers.c...o/noesis-215rt/

#5 dakos

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Posted 08 May 2014 - 11:05 PM

Hello there Rodney,
These are great speakers, never heard them myself but JTR makes solid products.

The 2000W the XLS makes in 4 ohm bridge pushes the amp to its limits. This operation mode is not that recommended although certainly doable. Also you should use as thick and as short speaker cables as possible.

Enjoy :)
Avi

#6 Rhed

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Posted 10 May 2014 - 11:19 AM

Thanks dakos.. Though I probably won't be using all that power. I don't want a amp to work hard. I want the amp to deliver clean power with ease. So more headroom I should say. Should I look into the 2500 model instead in bridge mode? Also, will the binding post on the XLS take a 10 awg wire? Thanks..

#7 dakos

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Posted 10 May 2014 - 05:29 PM

The XLS 2500 is about as powerful as the XLS 2000 for this application and would still be operated at the same mode as the 2000. I'm thinking more towards a couple XTi6002 (2100W per channel at 4 ohms). Since the amps sit in a different room we don't need to worry about fan noise, correct?

I went to the JTR website to see if they have speaker presets for your speakers that would require a more clever DSP such as the one found in the XTi or i-Tech amps but I couldn't find any. I just eMailed JTR support staff to get an answer to this issue so I'll update you as soon as I receive a reply from them.

10 AWG wire is not a problem. If it can't fit directly into the binding posts, you may simply use banana plugs such as these:
http://www.amazon.co...ds=banana plugs

Avi

#8 Rhed

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Posted 10 May 2014 - 07:01 PM

Ok thanks dakos.. Jeff at JTR is a great guy. I'm sure he'll answer your questions. Let me know what you come up. I didn't mentioned if it matters, that I was jus going to use the amps in bypass mode. And let the receiver do all the xovers. Not to familiar with dsp settings. Anyway, my speakers are still being made so I got time. I'm gonna also look into the XTi series. I'm actually also looking into a pre-amp instead of using my AVR now.

#9 dakos

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Posted 11 May 2014 - 01:37 AM

What receiver/processor are you planning to use? What subs? How big is your home theater?

Speaker presets are made mainly to compensate for any peaks or dips in the speakers frequency response. If they are available and you use them, if you encounter problems with the sound you can almost surely say that room acoustics is the one at fault and not the speakers. Room acoustics can't be solved using an EQ. Did you take care of the room acoustics?

All the amps discussed here don't have true bypass mode, in fact almost all amps made these days don't have true bypass mode. Even if you turn off all processing on the integrated DSP the signal still has to go through the AD/DA in the amp.

The audio in movie tracks is incredibly dynamic so I think I get what you're trying to do :-)

Would love to take a peek at your HT :-) , can you upload a picture or two?
Avi

#10 Rhed

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Posted 11 May 2014 - 11:56 AM

Thanks dakos for explaining what the speaker presets does. Learn something new everyday. My room I guess is fairly big (20Lx17Wx9H). The room is treated, but am looking into adding at the ceiling. My current reciever now is a old Pioneer. I know the RCA pre-outs are rated at 1.5Vrms. I was told it was more then enough to drive a pro amp.
http://www.pioneerel...ceivers/SC-09TX
I might try this route first by hooking my old AVR to the amps. If it works for me, I might just ride with it for awhile. If not, I'll just go pre-amp. The 2 I'm looking at right now is..
http://us.marantz.co...roductId=AV8801
http://www.onkyousa....ss=Preamplifier
The Marantz I know is on the pricey side. But I've been looking around online, and found some for almost a grand less. And I know the BB store we have here in Hawaii price matches anything online :).
For the subs, I'm currently using subs made from JTR also. I have 4 of these..
http://jtrspeakers.c.../captivator-s2/
I have a picture that I took a few months ago of my setup. Though a few changes been made on the acoustic part to date. How do I upload the picture here? I don't see a attach file icon to click on.
Doesn't the Xls also have built in dsp?

#11 dakos

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Posted 11 May 2014 - 12:57 PM

View PostRhed, on 11 May 2014 - 11:56 AM, said:

My current reciever now is a old Pioneer. I know the RCA pre-outs are rated at 1.5Vrms. I was told it was more then enough to drive a pro amp.
http://www.pioneerel...ceivers/SC-09TX
I might try this route first by hooking my old AVR to the amps. If it works for me, I might just ride with it for awhile. If not, I'll just go pre-amp.
It looks very good. The problem with the outputs is that on page 155 on the manual, under the audio section the outputs level is 0.475V. It looks like it's not enough but the option to connect and see what happens is a very good one.

View PostRhed, on 11 May 2014 - 11:56 AM, said:

The 2 I'm looking at right now is..
http://us.marantz.co...roductId=AV8801
http://www.onkyousa....ss=Preamplifier
The Marantz I know is on the pricey side. But I've been looking around online, and found some for almost a grand less. And I know the BB store we have here in Hawaii price matches anything online :).
If the levels aren't high enough I think you'd be better off to buy the cheap ART CleanBox Pro and not put another amp that I believe would add less quality to the whole system then the cheap Art Box.

View PostRhed, on 11 May 2014 - 11:56 AM, said:

For the subs, I'm currently using subs made from JTR also. I have 4 of these..
http://jtrspeakers.c.../captivator-s2/
What's powering them?

View PostRhed, on 11 May 2014 - 11:56 AM, said:

I have a picture that I took a few months ago of my setup. Though a few changes been made on the acoustic part to date. How do I upload the picture here? I don't see a attach file icon to click on.
You need to upload the picture to a picture hosting website such as tinypic or postimage.org , don't even need to register.

View PostRhed, on 11 May 2014 - 11:56 AM, said:

Doesn't the XLS also have built in DSP?
Yes, but it's much less flexible then the ones in the XTi or the i-Tech and you need that flexibility for presets. We'll wait and see what Jeff says.

Avi

#12 Rhed

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Posted 11 May 2014 - 01:40 PM

Yea, I've seen that on my manual before. I've done a lot of reading and asking questions about the preamp output of the receiver. I was told it should work. Don't know what this means. But read post #3476 and let me know what you think. http://www.avsforum....acc-thread/3450
I mean if not I might just go with a active converter box since the amps will be in another room as stated in my first post. And also what you recommended. But, since my receiver is old but still going strong, I was looking into one of the two preamps I listed. They have balanced outs. The subs that I have from JTRs each have a built in plate amp. The manufacturer of the amp is Speaker Power. I'll try to get the picture uploaded today. Thanks..

#13 Rhed

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Posted 11 May 2014 - 03:01 PM

http://postimg.org/image/dwncg6vcb/
http://postimg.org/image/f07gs5fzf/

Ok.. These are pictures from a few months ago. It doesn't look like this anymore. For I have spread my subs around the room to get a more even response. Sorry pictures look kind of grainy. I took it with my phone. I will take more pictures with my dslr when I get the new speakers and amps.. :)

#14 dakos

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Posted 11 May 2014 - 10:51 PM

The problem with these measurements is standardization. The Pioneer manual didn't write if the spec is a nominal voltage or not, I just assumed it is. The guy measuring the output on the forum might be correct but it seems to me that his measurements are not for nominal voltage but rather Max Voltage=Nominal + Headroom, While Nominal voltage = Noise Floor + Dynamic range without the headroom, so they could all be right. Pro audio amps such as the Crown XLS need a nominal input of 1.4Vrms=Nominal. You can look at the specs of the Onkio, XLR output level: Rated XLR Output Level 2.0V Vs Maximum XLR Output Level 11.0V. This shows the difference between Nominal and Max levels which the pioneer didn't have and I'm guessing that it's Rated RCA output level is 0.475V and it's Maximum RCA output level is 1.5V.

I didn't see you were talking about replacing the Pioneer with either the Marantz or the Onkio. Mistakenly I thought you were adding another component that's why I wrote you about lowering the sound quality. This could be a great choice :)
Avi

#15 Rhed

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Posted 12 May 2014 - 02:31 AM

Ok thanks. I understand now. So if I run my current receiver pre outs to a active converter. Then out via XLR to the pro amps. Is there downside in doing this? Does the converter box increase the signal to provide enough voltage  to the amp? Now I'm looking at different options. I think if this route works, then I might ride with it for awhile. Don't know yet though.