Welcome, Guest. Please Login or Register
Decware Audio Forums
04/24/14 at 01:19:56


Pages: 1
Send Topic Print
Bias Switch? (Read 2585 times)
BWR
Ex Member



Bias Switch?
12/30/05 at 14:55:10
 
Anyone know the difference in bias settings of the switch?
Back to top
 
 
  IP Logged
Steamer
Ex Member



Re: Bias Switch?
Reply #1 - 01/07/06 at 21:59:15
 
Which amp?I have se84cs monos.

Greg
Back to top
 
« Last Edit: 01/07/06 at 22:00:03 by steamer »  
  IP Logged
BWR
Ex Member



Re: Bias Switch?
Reply #2 - 01/08/06 at 04:03:49
 
[quote author=Steamer  link=1135958110/0#1 date=1136671155]Which amp?I have se84cs monos.

Greg [/quote]

I have the SE84C. The manual for the Select is vague regarding the bias switch settings.

BTW, which Rane model are you using? How do you have the Bag End subs arranged?

-- Bob


Back to top
 
 
  IP Logged
Steamer
Ex Member



Re: Bias Switch?
Reply #3 - 01/08/06 at 15:26:22
 
I am not sure how your bias swith effects the sound but the switch on my cs monos has a noticable effect,in the front position the sound is laidback not biased as hard as the rear which is louder more dynamic with better bass.I suspect tube life is shorter in the rear position.I think the c is the same as my cs.

As for the rane its the mojo 22,2way.

My signal path is as follows:
ML #39 signals to the Rane where its divided at 500hz,the highs to my CS monos hooked directly to the Altec 511B/902's,the lows to the Bagend ELF-M intergrator/xover that splits the signal at about 80hz.Above that to a Bryston 3B SS powering my LaScala bass bins below that to a Bryston 4B SS powering the BagEnds. I have the BagEnds behind the Scala's in the corners both pulled out as far as possible.The sound is very very good.I am thinking about stacking the Scala's on top of the Bagends to get them even further from the corners and get the Scala's back to where they were before the subs.

Here is a link on another thread I started after setting it all up:

http://www.decware.com/cgi-bin/yabb/YaBB.cgi?board=zen;action=display;num=113443...

Greg
Back to top
 
 
  IP Logged
BWR
Ex Member



Re: Bias Switch?
Reply #4 - 01/09/06 at 03:39:54
 
[quote author=Steamer  link=1135958110/0#3 date=1136733982]I am not sure how your bias swith effects the sound but the switch on my cs monos has a noticable effect,in the front position the sound is laidback not biased as hard as the rear which is louder more dynamic with better bass.I suspect tube life is shorter in the rear position.I think the c is the same as my cs.

As for the rane its the mojo 22,2way.

My signal path is as follows:
ML #39 signals to the Rane where its divided at 500hz,the highs to my CS monos hooked directly to the Altec 511B/902's,the lows to the Bagend ELF-M intergrator/xover that splits the signal at about 80hz.Above that to a Bryston 3B SS powering my LaScala bass bins below that to a Bryston 4B SS powering the BagEnds. I have the BagEnds behind the Scala's in the corners both pulled out as far as possible.The sound is very very good.I am thinking about stacking the Scala's on top of the Bagends to get them even further from the corners and get the Scala's back to where they were before the subs.

Here is a link on another thread I started after setting it all up:

http://www.decware.com/cgi-bin/yabb/YaBB.cgi?board=zen;action=display;num=113443...

Greg [/quote]

I guess I wasn't clear in my original post regarding the bias switch. I'm curious to know what the current (mA) differences are between the two switch settings.

So you've got three different amplifiers in your system, how did you go about balancing the system since each amp has a different gain? Are you using the pro versions of the Bryston amps with output level controls?

I take it that you're happy running stereo subwoofers?

-- Bob

Back to top
 
 
  IP Logged
Steamer
Ex Member



Re: Bias Switch?
Reply #5 - 01/09/06 at 13:50:11
 
Bob,
Yes I have the Bryston Pro amps and the input levels were a big help getting things balanced.It has taken me about 3 weeks to get it close(still not quite)at least I havent had to touch levels the last couple.If I feel the need for an adjustment its basicly with the level for the low output on the Rane and not much at that.I was chasing my tail for about a week LOL then finally lowered the input levels for the Brystons and WOW everything started to fall into place.I was tring to do everything with the Rane.As for the 2 BagEnds they were very easy to work with.The ELF Integrator gets alot of credit there and IMHO 2 subs are better than 1.They blend very well with the upper freq.

Greg
Back to top
 
 
  IP Logged
BWR
Ex Member



Re: Bias Switch?
Reply #6 - 01/10/06 at 03:49:31
 
Greg,

Congrats on getting stereo subs to work to your satisfaction. It's a tough nut to crack. I can see where subwoofer systems with crossovers above 100 - 120 Hz using low order filters would need two subs, because you can locate the bass coming from them. But in systems with 80 Hz crossover and steep filters, the sub should not be detectable -- we locate the higher harmonics coming from the main speakers and perceive them as the bass frequencies. It's a really neat trick.

If you think about it, it's difficult to find one good place for a sub in a room, trying to find two places is nearly impossible given the variations in room dimensions and furniture layout.

I understand that a researcher at Harmon International published a paper this past year showing that theoretically having multiple subs was beneficial, but in practice in most homes it just doesn't work. Even in studio environments, M&K believes that a single optimally placed sub is the best way to go.

You've obviously done some good work in setup.

-- Bob
Back to top
 
 
  IP Logged
dr._sleep
Ex Member



Re: Bias Switch?
Reply #7 - 01/10/06 at 19:12:03
 
BWR:

I don't recall seeing an answer to your bias switch question, I'll give it a try...

In the forward position the cathode paralleled resistor value is 2.5K, the grid is -4.6 volts with respect to the cathode, the B+ value is 284 volts DC, the anode voltage is 207 volts DC after the 47K plate load resistor.

In the back position the cathode resistor value is 960 ohms, the grid is -2.6 volts with respect to the cathode, the B+ voltage is 260 volts DC, and the anode voltage is 147 volts DC after the 47K resistor.  

Since you are obviously dropping more voltage across the tube in the "back" position, the tube is biased hotter, more current across the tube, and dissipating more watts, hence it's foward sound.

In the forward position, less voltage drop, less current, more space in the soundstage, etc.

Hope this is right and helps your understanding as I understand it.

dr._sleep
Back to top
 
 
  IP Logged
BWR
Ex Member



Re: Bias Switch?
Reply #8 - 01/11/06 at 02:59:44
 
Dr. Sleep,

Thanks for the info. I'll have to study the schematic in the user's manual to see if I understand. I'll post again when I have questions.

-- Bob
Back to top
 
 
  IP Logged
veryoldcat
Ex Member



Re: Bias Switch?
Reply #9 - 01/12/06 at 07:11:02
 
Practically speaking, the high bias position (on my CS, the switch position towards the back of the amp) is helpful for very very low volume listening.

The normal bias position (on my CS, the switch position towards the front of the amp) works best for ordinary to high volume listening.

In the end, I use the high bias position very infrequently.

Karl
Back to top
 
 
  IP Logged
Pages: 1
Send Topic Print