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ed schilling
Reply with quote  #46 

Hey Alan, The XLS have RCA inputs and the GG can drive 2 outputs so you should be fine. The XLS is designed to use "line level" not speaker level. They do not have a "high level" inputs, which is why we make a cable with a resistor to knock the signal down from the speaker connection to a level the RCA's can take. I prefer this to a connection from the preamp.

The only issue with the Y conn. will be if the XLS loads the preamp down and affects the quality of the main speakers. If it does then you'll just make the "speaker to RCA" cable.

Hope this helps, you'll like that amp!
ps.......I spent way too much time using paint to draw this cable....I wanted it to look "cheesy". It does but took me a long time.....drawing in paint is hard! I'll post it with the dimensions later, gotta run out for a while.

Alan Cohen
Reply with quote  #47 

I'm running it that way now with my little KLH subwoofer and I can't tell a difference in the mains when I disconnect. I guess it depends on the input impedance of the Crown.

Just in case, how many watt 600 Ohm resistor?

Yeah, I think that amp will work well. As long as it's quiet, I'm sure I won't be using 1/10th of what it's capable of.

BTW, these are what they will be supporting:

Ray P
Reply with quote  #48 
Thanks Ed, it will be useful to have the dimensions as a check (I can work with imperial or metric!).

Reply with quote  #49 
Crown lists the unbalanced input impedance of the XLS 1500 at 10k ohms which seems on the low side. So depending on the input impedance of your main amp, using a Y sord on the output could effect the low frequency cutoff of the GG preamp.
Alan Cohen
Reply with quote  #50 
I'm using the SOB for the time being which has a rather high input sensitivity of 2.2V.
Reply with quote  #51 

It's not the input sensitivity that I am refering to. When using a Y cord on the GG you are paralleling the input impedance of your SOB with the input impedance of your KLH sub.

The resulting impedance forms a resonance circuit with the output (coupling) cap in the GG.

The resulting cut off frequency can be calcullated but we need both input impedances. I assume your GG is stock and that the output cap is 1uf. Same as the GG shown in Bruce's book "Audio Reality".

I doubt there is any issues but if there was it would effect the KLH sub much more than your main speakers.
Bruce Rozenblit
Reply with quote  #52 
Keep the interconnects short.  The GG can drive both the Crown and an SOB, but don't load it up with a lot of cable capacitance.  Just mount the electronics near each other and use longer  speaker cable instead.  It's always best to put cable length in speaker cable and not interconnects.     
Reply with quote  #53 
Ed indicates that paralleling two subs and bridging his Crown amp turned out to be the best combo for him, rather than using seperate r/l sub channels.

What is the best way to derive a mono, hopefully line level, output from a GG that is also driving an S.O.B.?
Bruce Rozenblit
Reply with quote  #54 
His Crown amp does that for him.  Manually, it can be down with two mixing resistors.  I wouldn't use less than 20K at the sub amps's input.  These sub amps have tons of gain, so knocking down the signal a bit wont hurt anything.
Reply with quote  #55 
The Crown amp instructions say "Connect signal source to Channel 1 only using either the XLR, ΒΌ Inch, or RCA connectors."

Thus, I'm thinking that the mono signal needs to be provided to the amp at the input and that it does not sum the inputs. I'd like to think it is as simple as "Y"ing the r/l channels into the one input on the Crown, but usually, it is not as simple as it seems!

Any insights appreciated.
ed schilling
Reply with quote  #56 
Gtemple, you are correct. I use my high level connection cables into a "Y" into chan. 1. The amps internals are set to "bridged mono" and the 2 speakers in parallel are connected as per instructions. I may have "mis-described" the setup to Bruce leading him to conclude the amp was mixing the signal.
Hope this helps!
Alan cohen
Reply with quote  #57 
There is also an "Input Y" feature that's listed in Crossover mode. It might be available for Bridged Mono as well. 
Bruce Rozenblit
Reply with quote  #58 
Major discovery!  Stop the presses.  Forget all the rules!

I just did some extensive testing with the bucket sub in my system.  I had moved some things around and connected the GG to the 300B with 12 foot cables.  Previously, I had always used 6 foot cables.  The sound quality did deteriorate just a bit.  Then I hooked up the Bash amp through a Y connector with 6 foot cables.  The GG is now driving 18 feet of cables, a 100K load and a 20K load.  It was too much.  The sound became harsh and peaky.  Terrible.  I unhooked the Bash amp and there was a huge improvement. Went back to 6 foot cables and the velvety smooth sound was back.  

What I learned is that the GG just can't drive cables much longer than 6 feet.  I will no longer offer sub woofer outputs.  The best way to use a powered sub is to connect it to the speaker outputs.  I know this contradicts what everyone says you are supposed to do, but do it.

Use the sub to augment the bottom end, to fill in what's missing.  By using the high level sub inputs, the sub amp can be located anywhere.

If cables have to be long, put the length in the speaker cables, not the interconnects. I stated that in Audio Reality but forgot my own teaching.  Keep interconnects as short as possible.     

Alan cohen
Reply with quote  #59 
I have everything pretty close together. I have a 3' cable to my SOB now and can use the same for the Crown.
ed schilling
Reply with quote  #60 
Alan, make a high level cable. It will be better than splitting the GG signal regardless of cable length. Bruce didn't believe me either until he tried it. Just try it.
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