Pre-amp output signal booster?

[McChris]

TLDR;
Trying to hook up a Crown XLi1500 2 channel power amp to the front pre-amp outputs on a Marantz SR5008.
Unimpressed thus far.


I've read that the Crown XLi1500 is a pretty powerful amp for home stereo use, yet when hooked up to my Polk Monitor 60's, they're barely louder than just straight off the AVR.

I upgraded to a Marantz sr5008 (yeah I know it's old, but new to me). My other AVR didn't have pre-amp outputs and I was going to get a line level converter(?), but later read they can introduce noise and that's a shitty way to go. The Marantz has 7 channel pre-amp outs, I've got the Crown hooked to the Front pre-outs.

As I understand it, most AVR's don't live up to the .75 - 1.4 voltage input that the Crown expects for a signal, but some claim that's just fine, it still powers their tower speakers with lots of headroom left.

But me, I have the gains all the way up; and it's not much louder than just coming off the AVR's integrated amp. I've read that I can somehow boost the signal off the pre-amp outputs and then feed that into the Crown to get full potential. I don't fully understand what kind of device does this, or if this is even a viable approach.

Rather than risk damage to my equipment, I thought I'd reach out and ask for advice.

Thanks in advance
Chris

 

[McChris]

PS. Some dude on here answered a similar question by telling the OP what he was doing was idiotic.
If that's your tact, please help someone else.

 

[lovinthehd]

Usually the Marantz pre-outs would have sufficient voltage, particularly if you're using the .775V sensitivity setting on the Crown. Then again there's not a real huge difference just going to an external amp. You get at best a 4.8 dB advantage going from 100 to 300 watts. Did you run Audyssey or re-calibrate after adding the external amp? What speakers are you using?

I have five Crown amps myself and use them on Denon and Onkyo avrs that should have similar output to your Marantz generally, and four of the five are only 1.4V (gen 1 XLS DriveCore series), and I don't need to use the .775V setting using the one that has that option (four XLS1500s, one 2502).

ps any difference using rear panel pre-outs instead of front?

pps see they're Polk Monitor 60s.....

 

[Verdinut]

TLDR;
Trying to hook up a Crown XLi1500 2 channel power amp to the front pre-amp outputs on a Marantz SR5008.
Unimpressed thus far.


I've read that the Crown XLi1500 is a pretty powerful amp for home stereo use, yet when hooked up to my Polk Monitor 60's, they're barely louder than just straight off the AVR.

I upgraded to a Marantz sr5008 (yeah I know it's old, but new to me). My other AVR didn't have pre-amp outputs and I was going to get a line level converter(?), but later read they can introduce noise and that's a shitty way to go. The Marantz has 7 channel pre-amp outs, I've got the Crown hooked to the Front pre-outs.

As I understand it, most AVR's don't live up to the .75 - 1.4 voltage input that the Crown expects for a signal, but some claim that's just fine, it still powers their tower speakers with lots of headroom left.

But me, I have the gains all the way up; and it's not much louder than just coming off the AVR's integrated amp. I've read that I can somehow boost the signal off the pre-amp outputs and then feed that into the Crown to get full potential. I don't fully understand what kind of device does this, or if this is even a viable approach.

Rather than risk damage to my equipment, I thought I'd reach out and ask for advice.

Thanks in advance
Chris

Most AVRs have enough pre-out voltage output to reach 1.4 volts, the SR5008 does anyway and that should be sufficient to drive your XLi 1500 to its full rated power by fixing the sensitivity switch to 1.4v. Have you tried to put the sensitivity switch to the 0.775v setting? If so what did it do?

Did you drive the Monitor 60's with the AVR onboard L & R channel amps? Did it drive them adequately? Otherwise, I suspect that your RCA cables are defective or there could be a defect with the preamp-out section of the SR5008.

 

[lovinthehd]

Another thought, are you able to achieve clipping (via the indicators on the Crown)?

 

[Pogre]

I suspect your expectations are a bit too high. It takes a doubling of power just to gain 3 dB, and speakers have limits. As far as sound quality I wouldn't expect any change aside from being able to play a little bit louder before clipping.

 

[lovinthehd]

Looking at the manual I do not see a set of front pre-outs.....just inputs.

 

[Pogre]

I'm curious what spl levels you're getting at mlp? Do you have a spl meter? There are some free apps for cell phones that work well enough to give you a close ballpark. Also, how far do you sit from your speakers?

 

[lovinthehd]

I'm curious what spl levels you're getting at mlp? Do you have a spl meter? There are some free apps for cell phones that work well enough to give you a close ballpark. Also, how far do you sit from your speakers?

Might help if he uses the pre-outs, too Seems he's using a front panel input, not a pre-out.

 

[Pogre]

Might help if he uses the pre-outs, too Seems he's using a front panel input, not a pre-out.

Would it work at all hooked up to an input?

 

[lovinthehd]

Would it work at all hooked up to an input?

Well there is a guy on ASR who is feeding inputs to his pre-outs and saying magic happens with the internal amp section of a Denon, so I dunno, ain't gonna experiment with that.

 

[McChris]

Usually the Marantz pre-outs would have sufficient voltage, particularly if you're using the .775V sensitivity setting on the Crown. Then again there's not a real huge difference just going to an external amp. You get at best a 4.8 dB advantage going from 100 to 300 watts. Did you run Audyssey or re-calibrate after adding the external amp? What speakers are you using?

I have five Crown amps myself and use them on Denon and Onkyo avrs that should have similar output to your Marantz generally, and four of the five are only 1.4V (gen 1 XLS DriveCore series), and I don't need to use the .775V setting using the one that has that option (four XLS1500s, one 2502).

ps any difference using rear panel pre-outs instead of front?

pps see they're Polk Monitor 60s.....

I didn't know that, about no major gains going to 300W. I had it in my head that my AVR's rated power was based on it running only 2 channels (2 channels driven), and if you run more channels, that number is split amongst them. Assumed maybe 25W were going to the Polk 60's from the Marantz. And with this amp, I was going to blow past that by a factor of 10!
Again, noob here.

Oh, and by front pre-amp outputs, I meant for the "Front L/R" speakers.

Here's what I have hooked up for outputs:

 

[lovinthehd]

I didn't know that, about no major gains going to 300W. I had it in my head that my AVR's rated power was based on it running only 2 channels (2 channels driven), and if you run more channels, that number is split amongst them. Assumed maybe 25W were going to the Polk 60's from the Marantz. And with this amp, I was going to blow past that by a factor of 10!
Again, noob here.

Oh, and by front pre-amp outputs, I meant for the "Front L/R" speakers.

Here's what I have hooked up for outputs:

That clarifies things. Keep in mind to gain a mere 3dB in spl you need a doubling of power. EQ eats up power, too. Power only gets you so much in terms of loudness, your speakers' sensitivity comes into play as do the speakers' limits (they don't get infinitely louder), as well as your distance from the speakers.

The all-channels driven rating is only so useful; that you would actually have need for max full power simultaneously isn't all that high with surround content particularly; in the all-channel stereo mode you might have more equal use of power per channel (personally I don't care for that mode compared to a proper surround mode). The speaker draws what it needs at any given moment depending on your demands volume wise. Each channel of your Marantz is capable of 100 w at a given moment, and simultaneously somewhere between 60-70% of that.

Play around with this to get an idea of the relationship of power for spl at given distances. http://myhometheater.homestead.com/splcalculator.html

So, back to some unanswered questions. You have used the .775 amp sensitivity setting? Can you achieve clipping of the amp?

 

[McChris]

Most AVRs have enough pre-out voltage output to reach 1.4 volts, the SR5008 does anyway and that should be sufficient to drive your XLi 1500 to its full rated power by fixing the sensitivity switch to 1.4v. Have you tried to put the sensitivity switch to the 0.775v setting? If so what did it do?

Did you drive the Monitor 60's with the AVR onboard L & R channel amps? Did it drive them adequately? Otherwise, I suspect that your RCA cables are defective or there could be a defect with the preamp-out section of the SR5008.

Hi, thanks for the reply.

I have run it with .775v input sensitivity. It seemed like it got a little louder, but maybe it was just in my head. It it did, it wasn't obvious.

Thinking this thing had some punch, I played around by wiring up some Phoenix Gold DVC 15's (car subs). I knew those bad boys could take some juice, and I could play with 4ohm vs 8 ohm. I didn't dare drop them to 1 ohm, but I had them at 4 ohms and hooked up bridged. It didn't even push those well. Full gains on the crown, maybe like 80% full vol on Marantz.

I do have the Polk 60's running via onboard L&R channel amps. They get loud, but something feels off. Seems like they had a bit more thump(?) while running them off an old Pioneer vsx-521. It just sounded better somehow. I know this Marantz is far superior, so it's gotta be operator error.

I've used 3 RCA cords, one of them a brand new RCA to XLR cable (just to see if XLR hookup made a difference).

I got a good deal on the Marantz. $300 on ebay.

You might be right about a defective preamp out.

 

[McChris]

Another thought, are you able to achieve clipping (via the indicators on the Crown)?

Negative on the clipping indicators.

 

[McChris]

I suspect your expectations are a bit too high. It takes a doubling of power just to gain 3 dB, and speakers have limits. As far as sound quality I wouldn't expect any change aside from being able to play a little bit louder before clipping.

Pogre, I'm thinking that's a factor here as well. I was expecting to have the speaker wind blowing through my hair at 1/4 gain. lol

 

[lovinthehd]

As far as the gain setting, that's simply to accommodate the level of the pre-out. You can run it at max if necessary. Where are your gain settings?

 

[McChris]

I'm curious what spl levels you're getting at mlp? Do you have a spl meter? There are some free apps for cell phones that work well enough to give you a close ballpark. Also, how far do you sit from your speakers?

I'll have to try one of those apps again. Last time I played with one, I didn't understand what to do. And I think it needed to be calibrated, with an SPL meter, lol. Too many things going in the app and I wasn't motivated enough to figure it out.

Speakers measure in at ~7-8 feet using Audyssey setup. And that's accurate.

 

[McChris]

Well there is a guy on ASR who is feeding inputs to his pre-outs and saying magic happens with the internal amp section of a Denon, so I dunno, ain't gonna experiment with that.

Magic = melted solder accidentally shorted to input PCB traces

 

[McChris]

That clarifies things. Keep in mind to gain a mere 3dB in spl you need a doubling of power. EQ eats up power, too. Power only gets you so much in terms of loudness, your speakers' sensitivity comes into play as do the speakers' limits (they don't get infinitely louder), as well as your distance from the speakers.

The all-channels driven rating is only so useful; that you would actually have need for max full power simultaneously isn't all that high with surround content particularly; in the all-channel stereo mode you might have more equal use of power per channel (personally I don't care for that mode compared to a proper surround mode). The speaker draws what it needs at any given moment depending on your demands volume wise. Each channel of your Marantz is capable of 100 w at a given moment, and simultaneously somewhere between 60-70% of that.

Play around with this to get an idea of the relationship of power for spl at given distances. http://myhometheater.homestead.com/splcalculator.html

So, back to some unanswered questions. You have used the .775 amp sensitivity setting? Can you achieve clipping of the amp?

Correct, I have used the .775 amp sensitivity setting, in fact mostly.
I cannot get the amp to clip.

I mainly use it for music and I've had little luck with surround modes. Presumably because most music is 2 channel? So I use that multi channel stereo button often.

I just hooked up the Marantz to my network and poked around in the settings. Found one for input sensitivity that seems to make things come to life.

Haven't hooked up the Crown yet, but I'm hopeful this will cascade a stronger signal to the Crown.
Macbook -> HDMI -> Marantz -> RCA/XLR -> Crown -> Old Telephone Cord -> Polk 60's

(jk) ^

* I'll report back if this clears it up, can't do it tonight though. fyi