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Tube Radio
Reply with quote  #256 
Been awhile since I last posted here.

Figured I'd give an update.

Due to certain requirements of my small stereo system the sub is used with I could not use a speaker level signal.

What I did was to build a two way 24 DB/octave active crossover set for 70Hz using three quad op-amps. The signal for the low pass filter is summed by a couple of op-amps fed from the left and right inputs.

The crossover was built in an ammo case which I find are very good for electronic projects as by just connecting the case to the circuit ground or earth ground you then have a completely shielded box.

So far the initial tests show that the sub has literally disappeared because it integrates so well.

My setup consists of these components.

McIntosh C24 preamp.
Custom active crossover. 
Lafayette LA-375 amp.
Modified Olson S-850 speakers (better tweeters added super tweeter and proper crossover)
Bash 500 watt subwoofer plate amp.
Bucket sub. 

It actually sounds like the bass is coming from the Olson speakers instead of the sub and the sub sounds good for various different types of music.

Never thought I would like a sub being crossed over so low, but that just tells me I wasn't setting the subs up right when trying lower crossover frequencies.

Thanks so much for this wonderful project.

The crossover turned out so good and works so well with the bucket sub that I will use it every time I build a bucket sub.

If anyone is interested in building the crossover let me know and I can post the schematic.
Tube Radio
Reply with quote  #257 
Just picked up a pair of KLH 22A speakers last weekend and after a recap they sound good and the sub integrates with them much better than with the smaller speakers.

Preamp, main speaker amp, active crossover & main speaker amp power supply

Sub amp


The whole system sounds simply amazing. Would not have been possible without the bucket sub.
Reply with quote  #258 
Originally Posted by Bruce Rozenblit
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.     

Reply with quote  #259 
I understand the project details when using the Crown amps. However I have not seen any mention of using conventional amps and electronic x-overs.

The subs (2) will be for music only with their main use being for deeper and more accurate production of church/cathedral organ

I have a Hafler power amp (100W/channel) and Marchand 24db x-overs.

Will this give the same results in typical listening room?
ed schilling
Reply with quote  #260 
bjohng, get any of the Crown amps and build the "high level" cable. Sell the other stuff. You can use it but it'd be like putting crappy tires on your Lambo.
Reply with quote  #261 
So Ed, are you saying we should build it exactly as you have described?  
ed schilling
Reply with quote  #262 
For the sub itself......absolutely, any deviation is a different device. 

The Crown amps are simply the cheapest and best way to power them. 2 FFRS Mark 4:20i in parallel in mono and the amp (the smallest, the  XLS 1000) in bridged mono mode  makes 1100 watts and the sound is effortless at any level. I only use a "high level connection"....never a line level or split from pre amp. The high level cable is simply an rca with a 600 ohm resistor in line with the center pin on one end and bare wires  on the other end to connect in parallel with the main speakers on the power amp. The power amp will see no load to speak of.

Any of the XLS series will be killer............don't skimp on the amp! The subs are worth having the best and in this application the Crown is it.
alan cohen
Reply with quote  #263 
Originally Posted by ed schilling
For the sub itself......absolutely, any deviation is a different device. 

I built them well over a year ago, high level input, and exactly as prescribed. It's astounding how seamless they blend into my system. I'm running Bruce's 3W/Ch CFA into a pair of 102dB Altec A5s.

The beauty of these subs are that I can't even tell they are playing, that is until I turn the Crown XLS-1500 off...and the bottom drops out. I turn it back on and I hear all those low frequencies again. 

This system sounds so great that I don't even think about it. I just turn it on and listen. It's not until I start losing a little sparkle that I realize it's time to change the 6550s in the CFA. I just ordered and full complement of tubes and can't wait till they arrive and breathe new life into my tunes. 
Reply with quote  #264 

I may have a complication. The plan is to use these subs with mains that use MiniDsp for x-over and equalization. This means that signal to both amps is equalized. I do have 2nd clean output from preamp so can go direct to Crown amp. 

I know this is not your preferred hook up but will this compromise performance?

Reply with quote  #265 
Any of you guys know how to configure the crown for just one sub? I have to loose one as the Mrs is giving me grief the cowbag
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