News: Trouble logging in? Log in from the login page.
February 24, 2020, 03:32:34 PM

Author Topic: Quicksand monoblocks  (Read 2324 times)

0 Members and 1 Guest are viewing this topic.

Offline aragorn723

  • Sr. Member
  • ****
  • Posts: 867
Quicksand monoblocks
« on: January 17, 2015, 01:19:45 AM »
Hi,

Is it possible to do Quicksand monoblocks, to generate more power?  This would be for 8 ohm speakers.  Thanks!

Dave

Offline Bonzo

  • Full Member
  • ***
  • Posts: 243
  • My name is Marco, best known as Bonzo
Re: Quicksand monoblocks
« Reply #1 on: January 17, 2015, 03:35:25 AM »
If you take a look at the chipset's datasheet it's possible, and doing so allow you to get rid of the output caps too.
You need to carefully check the PCB to see how to do it.

Ciao!
Bisogna avere orecchio!

Offline aragorn723

  • Sr. Member
  • ****
  • Posts: 867
Re: Quicksand monoblocks
« Reply #2 on: January 17, 2015, 06:25:46 AM »
How complicated would it be to do this?  The datasheet is a little over my head.  It looks like bottlehead runs the chip on the lower side (it can handle up to 30v but Quicksand runs 18v) and running the chip at a higher voltage would generate more output (15 watts into 8 ohms using a 28V supply).  How many watts per channel would the standard Quicksand run with 2 12volt SLAs in serial (24v)?  Thanks,

Dave

Online Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 12153
Re: Quicksand monoblocks
« Reply #3 on: January 17, 2015, 09:01:39 AM »
You could totally convert the Quicksand to a monoblock, and I would encourage the project!

The big issue with doing so is that you need to feed the amp with a differential signal to drive both channels.  You could convert a Quickie to do duty in this position, which would involve using the hardware and tubes, but setting up the second half of a cathodyne phase inverter and sending that to the Quicksand.

Inside the actual Quicksand, you could decrease the inductance at the output and remove the output coupling caps.  If you do this, I would strongly recommend removing the ground posts on the speaker outputs, you don't want to forget that you have removed the DC blocking from the outputs of the Quicksand, only to provide an 8 Ohm path to ground later on.

You could also build the second Quicksand into the first.

If you're handy with perf board, you could also make a basic differential phase inverter out of maybe 6 mosfets.

-PB

(PS - we are here to support wacky stuff like this!)
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline aragorn723

  • Sr. Member
  • ****
  • Posts: 867
Re: Quicksand monoblocks
« Reply #4 on: January 17, 2015, 11:41:22 AM »
Paul,

What is a differential signal, and why is it needed?  This sounds like a fair amount of work, how much power would each channel have?  Would that be double the stock power?  8 watts?  Or maybe something else (not sure its a linear relationship).  Of course 2 quicksands would want 24V each, so maybe a good way to get that would be 2 SLAs each..  and of course the Quickie would probably want its own set of SLAs (3)..  7 SLAs later, it's time for a chassis just for power  8)

Dave

Online Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 12153
Re: Quicksand monoblocks
« Reply #5 on: January 17, 2015, 12:19:32 PM »
What is a differential signal, and why is it needed? 
See google for more info.  Basically, if you want one half of the amp to drive speaker + and the other half of the amp to drive speaker -, you need two out of phase signals.  A simple differential amplifier will give you this, or a tube circuit where the cathode resistor and plate load resistor are the same value (sounds simple, somewhat complicated to implement). 

This sounds like a fair amount of work, how much power would each channel have? 
Yeah, it's not going to be easy.  You'll get 8 Watts.  Power will go up as voltage is raised (to a point).  At 24V, bridged into 8 Ohms, you'd eek out about 25W. 
Of course 2 quicksands would want 24V each
Why?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline aragorn723

  • Sr. Member
  • ****
  • Posts: 867
Re: Quicksand monoblocks
« Reply #6 on: January 23, 2015, 03:15:10 PM »
Paul,

The 24v for each Quicksand would be in place of the c batteries..  Having the dedicated power for each will probably help with output power (though I'm sure there's a way to power both of 1 set of SLAs).  The thing I go back to is whether this will power my Def tech BP6Bs.  They are 91dB sensitivity, and have a minimum 20W power rating, is that a factor?

Dave

Offline Kentp

  • Newbie
  • *
  • Posts: 1
Re: Quicksand monoblocks
« Reply #7 on: March 15, 2015, 04:23:34 AM »
Hi.

One set of quicksand monoblocks, will drive my quad 63 maybe ?

BR Kent from Denmark