My Quicksand finally arrived decided to build mine modified from the outset and change some the components to my favourites. as you will see from the pictures,as bottlehead design good circuits from the outset dent straight for the modifications. Sound quality is very good treble light and airy with good definition bass solid tuneful informative midrange detailed balanced and even handed the sound of this little amplifier is extremely good.,i do use fostex 206e in a solo206 horn cabinets and have done so for at least ten yearswith these speakers there is a little too much midrange emphasis the quicksand seems to have tamed this somewhat resulting in a lovely listen .Imuzt temper these observations as the components will have to break in especially the Russian Teflon bypass caps and the wima poly props capacitors I have used also the battery pack has not been used as prefer to use car or sla battery as well as trichord never connected power supply .Anyway that's all for now going to listen to some more music.again thanks to the bottlehead crew for bringing fantastic gear to the impoverished among us .
Quicksand That Sinking Feeling
- Thread starter aleman
- Start date
There are some reasons for the capacitor choices on the Quicksand PCB, especially C5/C6. Did you listen to the Wimas vs. the Tantalum caps?
Iam not an engineer I go with what I have used before if it does not breach any trade secrets could please enlighten me as to why they were preferred so that I may learn for future reference . the amp still sounds very good to my ears I must confess I did not listen prior to installing the caps.
The datasheet for the chip itself calls for a tantalum or ceramic cap for C5, and that would be the one place where I wouldn't mess around too much. Other selections may or may not lead to a noisier amplifier with additional distortion that wouldn't otherwise be there.
The other recommendations in the application sheet tend to make some assumptions (in my opinion at least) that the power supply available is marginal, so experiments with the power supply caps dotting the PCB should be harmless and fun to experiment with. The cap at C5 functions in a more isolated fashion with respect to the power supply, so I deferred to TI's recommendations in its selection.
Another thing you could try is making C2/C8 much, much larger, or considerably smaller.
-PB
The other recommendations in the application sheet tend to make some assumptions (in my opinion at least) that the power supply available is marginal, so experiments with the power supply caps dotting the PCB should be harmless and fun to experiment with. The cap at C5 functions in a more isolated fashion with respect to the power supply, so I deferred to TI's recommendations in its selection.
Another thing you could try is making C2/C8 much, much larger, or considerably smaller.
-PB
Thanks for the reply I suppose I should google the chip and specs and have a good read ,changing the caps value of c2 /c8 what would the effects be I had considered some sanyo oscons low esr types however the voltages seem to be limited any advice on the lowest voltages for c2/c8 I could get away with as well as upper and lower values as guidance .look forward to your reply.
Natural Sound
New member
I know that to some of you this is beating a dead horse but... It is recommended to build these kits with the supplied parts first. Listen for a while to get a baseline and then experiment away. The only other thing to add would be to only make one change at a time. If you change a bunch of parts at once and something goes wrong you won't know where to start troubleshooting. I know from years of experience that some "upgrades" make things worse. Always start with a stock build first.
aleman said:
I wouldn't go below 20V. For C2/C8, try 100uF caps, then maybe 10,000uF.
-PB
C5 replaced with original ceramic capacitor sat with wife to listen amplifier sounded in my wifes word oh very nice fronted of course by the unmodified quickie preamp looks like TI were right have changed nothing else further listening required, also to allow the components to run in.Have acquired some lowther dx3 drive units refurbished with receipt's for work done would like to use with this amplifier but due to switch on thump unlikely to use unless anyone has any suggestions for getting around this problem.Advice appreciated.thanks
Is the thump actually louder than the music played through the amp?
But is it louder than something like a large drum playing through your system?
If it's a ton louder, then you can just pop off the speaker connections while you switch the amp on. If the thump is consistent with loud transients in the source material you listen to, there's nothing to worry about.
If you had super high efficiency horns and wanted to run the Quicksand directly to the horn with no blocking cap, that would be the kind of situation where the turn on thump could cause a problem.
If it's a ton louder, then you can just pop off the speaker connections while you switch the amp on. If the thump is consistent with loud transients in the source material you listen to, there's nothing to worry about.
If you had super high efficiency horns and wanted to run the Quicksand directly to the horn with no blocking cap, that would be the kind of situation where the turn on thump could cause a problem.
It's probably easiest to have a switch that shorts the + outputs of the Quicksand to ground. (No harm done)
That way, once the Quicksand is on, you can open the switch and let it play, and the switch will be out of the signal path.
-PB
That way, once the Quicksand is on, you can open the switch and let it play, and the switch will be out of the signal path.
-PB
Would it be possible for you to sketch a quick diagram for the technically challenged to implement this as this looks like an ideal solution to my particular problem with regard to using my lowther drivers all I will have to do now is find a suitable small horn cabinets to build as space is limited any pointers would be useful. thanks a lot
aleman said:
Run a wire from left positive speaker terminal to terminal A on the switch.
Run a wire from right positive speaker terminal to terminal B on the switch.
Run a wire from one of the negative speaker terminals to C and D on the switch.
-PB
