New ESL owner- ReQuests, a few questions about power and bi-amping

[DavidWhelan]

Hi Everyone!

Thank's for welcoming another "newbie" into your community!

Last weekend purchased a pair of early reQUESTs (SN 50/51) after auditioning them. They sounded fantastic and appear to be in pristine condition - I'm so excited I've finally stepped into ESL speakers!

I have a few setup questions I'm hoping to get assistance with here. In my 18x20 foot living room, I mostly listen to Jazz, Folk, electronic, classical with very occasional rock music.

My system includes a MacBook Pro laptop playing HD audio files through my Apogee Duet 2 DAC into a Cary SLP-30 tub pre-amp into an Adcom GFA-5500 AMP into a pair of Mirage 1090i speaker.

While my Adcom GFA-5500 is rated 200W (into 8 ohms) / 350W (into 4 ohms) per channel, I've read the ReQuests really "light up and shine" with lots of power. So, I've just purchased two Adcom GFA-5802 (300W @ 8 ohms / 450W @ 4) amps.

Running two Amps at once brings up a few questions:

Question #1: Per the reQUEST manual, Horizontal bi-amping or Vertical bi-amping are options. Since I'm running identical amps, which is the best option for me? Does Vertical amp setup require the amps be monoblocks?

Question #2: This might sound silly, but is it possible to have too much power, so I have to worry about damaging the speakers?

Question #3: Will splitting the outputs from the pre-amp into the two amps degrade the signal, resulting in less optimal sound stage, etc? If so, should I look at options to utilize the XLR inputs on the amps (my DAC provides single set of stereo XLR outputs)

Any suggestions / recommendations regarding the above would be greatly appreciated!


Thanks!

David Whelan

 

[Rehan Azim Hashmi]

Introduction:
Since you say any suggestions are appreciated I will try to answer 3 questions.
I hope others will contribute where I have left out due to lack of knowledge and also point out where I
am wrong or unintentionally misleading. My intention is to offer guidance and not to mislead you.

1a.
Since you are running identical amps horizontal bi-amping should be good.
Attach one 5802 left terminal to the left woofer and attach right 5802 terminal to
right woofer. In the same way attach the other 5802 left terminal to the left panel and right
5802 terminal to right electrostatic panel.

1b.
I do not know whether vertical amp setup requires the amps be monoblocks.

2.
It is possible to have too much power. However your loudspeaker has fuse in them.
Please make sure the fuse inside the loudspeaker is precisely the right ampere value and quick blow.
5802 I do not think put forward too much power to reQuest loudspeakers. My guess would be put
forward just the right amount of power.

3a.
Yes splitting the outputs from the preamp into the two amps will weaken the signal resulting in less
optimal sound stage etc. You may have to increase the volume of your preamp.

3b.
If your DAC has both stereo XLR output and stereo RCA output and both operate at the same time.
Then connect DAC variable output whether it is XLR or RCA directly to one 5802.
Attach the DAC fixed output to the preamp. From the preamp connect XLR to second 5802 XLR.

Conclusion:
To conclude, I have never tried this therefore some of my suggestions are educated guesses.
Why do you not experiment and try all the various combinations and determine which sounds best for
you. If you keep the DAC and preamp output level at, the maximum, at moderate intensity your
reQuest should be safe. Attach the tube preamp to the 5802 and then connect to electrostatic panel.

 

[Bernard]

I won't comment on vertical vs horizontal biamping as I have no experience there, but I have to disagree with M15 on a couple of points:

2)The question of too much power. You cannot have too much power; your ears will tell you when you should back off, long before the fuse blows. It is, however, possible to do more damage with too little power - if you drive an amp into clipping you will be feeding your speaker with square waves (DC).

3a)Splitting the output from the preamp into two power amps will not weaken the signal. Typically power amps have high enough input impedances that they will not load down the preamp when you have two in parallel.

 

[DavidWhelan]

M15,

Thank you so much for all your suggestions / recommendations! It's an exciting time here, waiting for all my new toys to arrive! As you recommend, I'll definitely check the fuses in the speakers!

My next step is to modify my cabinet to hold the two amps - I've read they can run Class-A and become quite hot. I've bought a few temperature controlled fans but it seems odd to me to put the amps on the top shelf and my tub pre-amp and laptop on the lower shelf... Do you know if it's really best to put the hottest running components higher up?

Thanks!

David

 

[DavidWhelan]

Bernard,

Thank you for your input too, I really appreciate it! There's many combinations I can play with (isn't this hobby great!), including maybe hooking the XLR outputs from my DAC (which has a pre-amp gain built into it) directly to the amps (using XLR splits), thus eliminating my tube pre-amp. The music might sound to bright, but with less in the signal path, maybe even 'cleaner'... We'll see.

Anyway, thanks again for your advice / input!

-David

 

[Rehan Azim Hashmi]

M15,

Thank you so much for all your suggestions / recommendations! It's an exciting time here, waiting for all my new toys to arrive! As you recommend, I'll definitely check the fuses in the speakers!

My next step is to modify my cabinet to hold the two amps - I've read they can run Class-A and become quite hot. I've bought a few temperature controlled fans but it seems odd to me to put the amps on the top shelf and my tub pre-amp and laptop on the lower shelf... Do you know if it's really best to put the hottest running components higher up?

Thanks!

David

David,

Glad I could be of some assistance to you.

If you have only one cabinet for everything it is better to put the amplifiers on top, side by side, no obstruction over the power amps.

However I would suggest you place both 5802 , one in front of the other, on the floor in the middle of the 2 ML’s. Place each amp on two paving blocks with space between the 2 blocks for convection cooling. This way the amp output terminals will be on the same level more or less as the loudspeaker terminals. Therefore gravity will not work against speaker cable signal flow.

M15

 

[Rehan Azim Hashmi]

David,

Please when all your “toys” have arrived and you have a final system ready please do post images and information pertaining to your system under member systems.

Thanks very much,

M15.

 

[Rehan Azim Hashmi]

I won't comment on vertical vs horizontal biamping as I have no experience there, but I have to disagree with M15 on a couple of points:

2)The question of too much power. You cannot have too much power; your ears will tell you when you should back off, long before the fuse blows. It is, however, possible to do more damage with too little power - if you drive an amp into clipping you will be feeding your speaker with square waves (DC).

3a)Splitting the output from the preamp into two power amps will not weaken the signal. Typically power amps have high enough input impedances that they will not load down the preamp when you have two in parallel.

Bernard, thanks very much for your constructive critique.

 

[Spike]

David,
Since you have 2 identical amplifiers (Adcom 5802) you should explore vertical bi-amping to eliminate any chance of cross-talk between the left and right channels.

I've read the ReQuests really "light up and shine" with lots of power.

I would caution that it has more to do with the QUALITY of power than QUANTITY.

Good luck with your system,
Spike

 

[DavidWhelan]

Hi Everyone!

Got the system hooked up - only using one Adcom GFA-5802, as there's issues with the second one I bought

System sounds very clean and open, Bass seems deep, well controlled and accurate, but system appears to have a bit of an 'echo' during vocals... think room treatments are next.

Are there any nifty 'setup' procedures I can use, someone mentioned a "flashlight trick"?

Thanks Everyone!

-David

 

[RUR]

Are there any nifty 'setup' procedures I can use, someone mentioned a "flashlight trick"?

Flashlight trick: https://www.youtube.com/watch?v=vsBUFCsyP4s

If at all possible, I'd pull those speakers away from the front wall. Three feet is generally considered an OK distance, though folks have done with less.

 

[DavidWhelan]

Rur - thank you!

-David

 

[Rehan Azim Hashmi]

Like picture of your pet house cat. I take care of 8 pet cats that are kept outdoors. There used to be 11 but unfortunately

three of them recently passed away.

Some, 3 to be exact, resemble your pet cat. They are fed a kilogram of chicken over two days along with milk and bread.

Please if you want your panels to last, keep them away from ultraviolet rays in sunlight. Same applies to woofer.

Thanks for posting images of your system. The Logan’s look majestic and great.

Have fun listening to music on your system!

 

[Bernard]

Cats have been known to climb up ML grilles.

 

[Rehan Azim Hashmi]

Cats have been known to climb up ML grilles.

Indoor pet cats typically do not climb up ML grilles.

However if a outdoor stray cat in the lookout for something to eat for they are malnourished enters indoor then cat will climb windows

or closed doors and perhaps even ML’s in their panic to escape outside.

The above has occurred a number of times over past 15 years and is in my experience. Luckily my ML’s the cat did not climb and so cat remained safe.

Have fun listening to music!

 

[RCHeliGuy]

This was a concern for me as well, but I have 4 cats and they haven't messed with my Ethos speakers at all.

I also worried that they might get up on the woofer box, but that hasn't been an issue either. I've let dust accumulate back there and I've never seen a foot print.

 

[DavidWhelan]

Everyone,

As for the possible scratching problems, per my buddy's recommendation, I placed the scratching post near the ML's and the cats haven't touched them ONCE (finger's crossed).

Good news is the two Adcom Amps came, bad news is they BOTH had issues. What I didn't mention earlier was my friend (who's an EE) came over and with board swapping, bias adjustments, etc, was able to get one Amp working really well. Sound is fantastic - very open in vocals and bass is tight and controlled.

Just ordered two of these little boards (again as recommended by EE friend) to protect my speakers against possible AMP failure:

http://www.ebay.com/itm/141708401105?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Only problem is room acoustics - there's a definite echo or "ping" back and forth sound when I clap hands. Looking at a few options that won't lead the wife to killing me...

Might be able 'sell' these to the significant other as 'pretty', yet hopefully will greatly help with the echo...

http://www.acoustimac.com/


or, this foam is said to be quite good, much more affordable and available in a range of colors (bonus!)

http://www.foambymail.com/AW4/acoustical-4-wedge-foam.html

Great hobby!

Thanks everyone!

David

 

[Gordon Gray]

Hi David,

You definitely have a "lively" room. Pulling the speakers five feet out should help "some" by attenuating the amount of "bounce" you get off the back wall.

There are potential alternatives to the panel solution to tame the reverb and reflections in your room. Synergistic Research (and other companies) make some unconventional acoustical treatment products that some say are voodoo and others say work quite well.

I have had some personal experience with these at past audio shows and they did seem to work.

Only way is to try (with a money back guarantee) and see what you think.

Best,

Gordon