Request for pro amp reviews

[AcuDefTechGuy]

The only "issues" I see with the Crown amps is the lack of 12V trigger and you have to turn that gain knob to about 80%.

And you have to removed that stupid plastic plug on the speaker posts - like the plugs on the Infinity P363 speaker posts. Then you can use banana plugs.

Some people feel "uncomfortable" about turning that gain knob to 80%. But I guess they don't realize that most amps are actually turned to 100% fixed gain and you cannot change the gain.

They operate very cool and efficient, and sound just like any other amp as long as you turn that gain level up.

Andrew Robinson said they sound better with more efficient speakers?

Duh. They sound LOUDER with high efficiency speakers. Not better or worse.

Andrew Robinson also said "keep the gain controls off"? I don't get it. If the gain is zero (assume off = zero), how do you get any sound?

Another guy said he set the gain above 3 o'clock, which is ~80%, to which Andrew Robinson replied "Don't go too high with the gain".

Well, you have to level match. Either increase the gain on the AVR or the gain on the amp. So Andrew Robinson sets his Crown amp gain to 50%, but cranks up his surround channel levels to +8.5dB to attain 75dB on his SPL meter.

 

[Sugarbear]

I been reading it... this is one very interesting post:
Crown Audio XLS Drivecore Series Amplifier - The OFFICIAL Thread - Page 4

I picked up on that one too. Very good thread.

 

[cpp]

*If it weighs a lot

yep forgot about that one

 

[jinjuku]

I been reading it... this is one very interesting post:
Crown Audio XLS Drivecore Series Amplifier - The OFFICIAL Thread - Page 4

Starting with the 1500 it has 6dB better S/N than the 1000 (at 97). The 2000 and 2500 most likely have a more stout power supply which could also help over the 1500.

The Yamaha P2500 I believe has an SNR of 107dB.

Luckily with my setup I can drive balanced connections no problem. I have to use an ART Cleanbox Pro on the XLS series if driving them with my Denon. This is one of those few times that the term 'Synergy' matters.

 

[jinjuku]

The only "issues" I see with the Crown amps is the lack of 12V trigger and you have to turn that gain knob to about 80%.

Some people feel "uncomfortable" about turning that gain knob to 80%. But I guess they don't realize that most amps are actually turned to 100% fixed gain and you cannot change the gain.

Agreed on the part about amps with fixed gain.

Andrew Robinson also said "keep the gain controls off"? I don't get it. If the gain is zero (assume off = zero), how do you get any sound?

That had me scratching my head also. I wonder if he meant the clip limiter (which I recommend keeping off also)?

Another guy said he set the gain above 3 o'clock, which is ~80%, to which Andrew Robinson replied "Don't go too high with the gain".

I think Andrew is talking about getting into gain induced hiss. I know with some other products you only increase signal by +6dB to get rated output from an un-balanced connection.

Well, you have to level match. Either increase the gain on the AVR or the gain on the amp. So Andrew Robinson sets his Crown amp gain to 50%, but cranks up his surround channel levels to +8.5dB to attain 75dB on his SPL meter.

He needs to find out from Crown if the attenuation is linear or not on the knobs. He needs to simply grab an SPL meter and play pink noise with his AVR set back to defaults. Adjust the gain on the amp to say up to 3/4's and see if the speakers output is where he needs it. If not then start bumping line level in the AVR.

 

[KEW]

That had me scratching my head also. I wonder if he meant the clip limiter (which I recommend keeping off also)?


I think he worded it wrong. A gain or volume control is an attenuator. Looked at that way, turning it off (bypassing the attenuator) is all the way up.

 

[KEW]

*If it weighs a lot

The Pro Amp world is definitely a different world!
Yamaha P2500S (250W X 2 @8ohms) weighs 30.9 lbs
Yamaha P3500S (350W X 2 @8ohms) weighs 33.1 lbs
Yamaha P5000S (500W X 2 @8ohms) weighs 26.5 lbs
Yamaha P7000S (700W X 2 @8ohms) weighs 26.5 lbs

So, the overall trend for these Yamaha Pro amps is as the power and price goes up, the weight goes down!
P-S Series | Power Amps | Products | Yamaha


The Crown amps don't follow the same trend, but they are less than 1/3rd the weight of the Yamahas!

XLS1000: 8.6 lb (3.9kg)
XLS1500: 8.6 lb (3.9kg)
XLS2000: 10.75 lb (4.9kg)
XLS2500: 10.75 lb (4.9kg)

XLS Drivecore

 

[AcuDefTechGuy]

I just retired my OSD "home" amp (which was powering my 4 Velodyne SC600 subs) into the closet and replaced it with a Crown XLS 2500 "pro" amp.

The OSD's buzz was bugging the heck out of me. The Crown has no buzzing noise.

Mode: Stereo Bypass, Clip On (limiter on).

2 subs per channel wired in series, gain 100%.

Can't prove the sound is better objectively, but subjective heck yes it sounds much better.

I suppose with no buzz and less distortion and higher quality, the sub SQ has benefitted from the Crown amp.

The little Dynaudio X32 sound fantastic with great resolution with the 4 Velodyne handling the bass.

Crown amps are great.

 

[ahblaza]

Starting with the 1500 it has 6dB better S/N than the 1000 (at 97). The 2000 and 2500 most likely have a more stout power supply which could also help over the 1500.

The Yamaha P2500 I believe has an SNR of 107dB.

Luckily with my setup I can drive balanced connections no problem. I have to use an ART Cleanbox Pro on the XLS series if driving them with my Denon. This is one of those few times that the term 'Synergy' matters.

Jin, will http://www.amazon.com/ART-CLEANBOXPRO-CLEANBoxPro/dp/B003S7T49K/ref=sr_1_1?ie=UTF8&qid=1346809078&sr=8-1&keywords=Art+clean+box+pro convert a RCA preout cable to balanced cables for use with my XLS, and do I need this, I have XLS1500 being driven from my AVR analog preouts to amp, there is a slight barely audible hum about two inches from drivers with gain set at 100% on amp. I think I will try what you suggested about setting AVR level to default and amp gain 3/4 up and measure at LP with SPL meter to reach 75dB, I'm kind of thinking that the ART box just adds for me another device in the signal chain but if you think it would help I'll go for it. Thanks.
Jeff

 

[jinjuku]

Jin, will Amazon.com: ART CLEANBoxPro: Musical Instruments convert a RCA preout cable to balanced cables for use with my XLS, and do I need this, I have XLS1500 being driven from my AVR analog preouts to amp, there is a slight barely audible hum about two inches from drivers with gain set at 100% on amp. I think I will try what you suggested about setting AVR level to default and amp gain 3/4 up and measure at LP with SPL meter to reach 75dB, I'm kind of thinking that the ART box just adds for me another device in the signal chain but if you think it would help I'll go for it. Thanks.
Jeff

The cleanbox is needed only if your AVR isn't able to drive the Crown to full output. Which it sounds like your is indeed doing.

From what you are telling me you don't need the clean box.

 

[AcuDefTechGuy]

there is a slight barely audible hum about two inches from drivers with gain set at 100% on amp.

Hum or hiss?

The hiss is normal, but the hum is ground loop noise - cables lines and such, which is always a potential problem with all external amps, including ATI, Mark Levinson, Krell, etc.

In my experience XLR cables will not get rid of the ground loop hum; only eliminating those wiring and cabling will do.

It's not recommended, but some of us use the "cheat plug", which converts the 3-prong plug into a 2-prong plug without the Grounding.

No grounding = no ground hum.

My Denon 5308 w/ 150wpc x 7ch uses a 2-prong plug.

But it's not recommended by electricians. You can use it to check if it is ground loop.

 

[KEW]

The cleanbox is needed only if your AVR isn't able to drive the Crown to full output. Which it sounds like your is indeed doing.

From what you are telling me you don't need the clean box.

Can you elaborate on this?
How would you determine if the pro amp wasn't being driven to full output?

 

[jinjuku]

Can you elaborate on this?
How would you determine if the pro amp wasn't being driven to full output?

The easiest indicator is if when getting on the AVR volume the signal lights on the Crown aren't doing much.

There are more technical ways but you really just need to watch the signal indicator.

 

[ahblaza]

The easiest indicator is if when getting on the AVR volume the signal lights on the Crown aren't doing much.

There are more technical ways but you really just need to watch the signal indicator.

Thanks Jin, there is a lot of action with the signal lights of the crown with the AVR driving it, you saved me $70 for something I really don't need.

 

[ahblaza]

Hum or hiss?

The hiss is normal, but the hum is ground loop noise - cables lines and such, which is always a potential problem with all external amps, including ATI, Mark Levinson, Krell, etc.

In my experience XLR cables will not get rid of the ground loop hum; only eliminating those wiring and cabling will do.

It's not recommended, but some of us use the "cheat plug", which converts the 3-prong plug into a 2-prong plug without the Grounding.

No grounding = no ground hum.

My Denon 5308 w/ 150wpc x 7ch uses a 2-prong plug.

But it's not recommended by electricians. You can use it to check if it is ground loop.

Thanks buddy, I had some hum in one of my subs last night that I did not have before the crown being in the setup, I moved the sub cable around and away from any power cables and seemed to help a lot. I will check it out today with and without the crown in the system and also with cheater plug, I just think I'm too paranoid, I like dead dark silence
Cheers Jeff

 

[panteragstk]

From what I know of external amps is that if the input voltage isn't where it needs to be the amp won't be able to reach it's full potential. That's why XLR is used for the long runs (IIRC).

 

[ahblaza]

From what I know of external amps is that if the input voltage isn't where it needs to be the amp won't be able to reach it's full potential. That's why XLR is used for the long runs (IIRC).

I haven't even come close to using the full potential of this amp, there is a lot of reserve power in this amp, and I don't have to be concerned with long cable runs either. Thanks
Jeff

 

[slipperybidness]

Thanks buddy, I had some hum in one of my subs last night that I did not have before the crown being in the setup, I moved the sub cable around and away from any power cables and seemed to help a lot. I will check it out today with and without the crown in the system and also with cheater plug, I just think I'm too paranoid, I like dead dark silence
Cheers Jeff

If it is a long subwoofer cable, it is a good idea to use shielded RCA cable.

 

[slipperybidness]

Thanks buddy, I had some hum in one of my subs last night that I did not have before the crown being in the setup, I moved the sub cable around and away from any power cables and seemed to help a lot. I will check it out today with and without the crown in the system and also with cheater plug, I just think I'm too paranoid, I like dead dark silence
Cheers Jeff

If I use a cheater, I feel more comfortable by also using a GFCI. Just some extra precaution since you are defeating a safety mechanism. One of those portable GFCIs for power tools can plug in anywhere.

 

[ahblaza]

If I use a cheater, I feel more comfortable by also using a GFCI. Just some extra precaution since you are defeating a safety mechanism. One of those portable GFCIs for power tools can plug in anywhere.

Hey Slip, I used the cheater on the Crown plugged into my Tripp Lite HT10 and all is dead silent quiet even with gain on the amp at 100%. Is this what you're talking about, and if so I can't use this with the Tripp lite right?
TRC 90033 Shockshield White Portable GFCI Plug with Surge Protection - Amazon.com
Thanks Jeff