Newbie Questions

[irishpatrick33]

I've got a Quicksand kit that I will build in the near future. I have a couple questions before building if anyone doesn't mind answering.

I'm assuming the voltage levels dip as the battery charge dissipates, is there a simple way to ensure the amp is always getting 18V? I don't want the quality of performance changing depending on charge. Or is that not an issue?

Also, the plan is to use a metal enclosure. However the instructions do not address how this would affect the build. Would it? Should I ground the case to the board? Do I allow the power switch to contact the case, because it looks like all other parts are insulated from the pseudo case? Etc.

[Paul Joppa]

Youu can use nickel cadmium or nickel metal hydride rechargeable cells - the voltage will be lower, around 15 volts, but they do not drop off as they discharge. Capacity is significantly less than alkaline cells, but this does nt require any changes to the build.

Some customers have implemented rechargeable power packs from other machinery, model cars, etc. That's a more complicated exercise!

[irishpatrick33]

Thanks Paul! That is convenient, as my plan was to use rechargeables.

o-o-o-o-o

Anyone have thoughts on how a metal enclosure build differs from instructions?

[Paul Birkeland]

I'm assuming the voltage levels dip as the battery charge dissipates, is there a simple way to ensure the amp is always getting 18V? I don't want the quality of performance changing depending on charge. Or is that not an issue?

The Quicksand will work at just over 6V, but at reduced power.  If you end up using a fair amount of the available power, you'll hear the amp start to clip as the batteries dip.

Also, the plan is to use a metal enclosure. However the instructions do not address how this would affect the build. Would it? Should I ground the case to the board? Do I allow the power switch to contact the case, because it looks like all other parts are insulated from the pseudo case? Etc.

The big issue that we have seen is that the 2200uF caps need to be laid down to fit.

Since the kit is still battery powered, grounding of the metal chassis isn't nearly as critical as it might otherwise be.  I would just ground the center lug of the 5 lug terminal strip to a spare ground terminal on the PC board and call it a day.

-PB

[irishpatrick33]

Two questions. Any help is appreciated. If helping, please explain as you would to a baby.

1) If I want to run 24V, exactly what type capacitors should I buy and where do I implement them?

2) I plan on building my quicksand as a hybrid with a Pass Korg B1. The buffer requires exactly 24V. This poses a problem, as battery voltage varies. Would a regulator work? If so, do you know of DIY plans or units for sale? Though my understanding is a regulator will prevent over-voltage, but won’t prevent under-voltage. Is there such a thing that will prevent voltage from going higher and lower?

[Paul Birkeland]

1) If I want to run 24V, exactly what type capacitors should I buy and where do I implement them?

If you're going to use 16 C cell batteries, then your starting voltage will be over 25V, so the 25V caps need to be swapped out for a higher voltage rating.

2) I plan on building my quicksand as a hybrid with a Pass Korg B1. The buffer requires exactly 24V. This poses a problem, as battery voltage varies. Would a regulator work?

Are you planning to run the B1 on a set of car batteries?  How much battery life are you looking for?

If so, do you know of DIY plans or units for sale? Though my understanding is a regulator will prevent over-voltage, but won’t prevent under-voltage.

I don't foresee any disaster if the B1 sees more than 24V (or a little less for that matter).  Nelson is a smart guy, if 24V was absolutely critical, he would regulate the power supply.

Is there such a thing that will prevent voltage from going higher and lower?

A DC to DC converter could be used to do this, but I wouldn't recommend it. 

[irishpatrick33]

The Korg B1 performance is voltage dependent. Some people are using regulators to feed it. However, I am implementing a battery supply for this Quicksand, and because of that I worry that voltage drop will significantly affect me unlike others, whom are regulating a SMPS.

I haven't decided what type of battery to use yet. Listening time isn't critical, as long as it lasts through an evening. If I regulate, then use Ni-MH or Ni-Cad batteries, would that eliminate the need for a DC-DC converter? Meaning, those batteries in combination with regulator would get a stable 24V that doesn't dropoff until nearing full discharge. The battery seems like the most flexible component and I will do whatever is best, no real preference.

I see (3) 25V caps in the parts:

• One is the C13. Would UES1V100MEM1TD suffice? I think I would have to mount in on opposite side to fit it.
  
• I see 6 possible replacements for C2 and C8 - UFW1V471MPD1TD, UKW1V471MPD, UFG1V471MHM, UFG1V471MHM1TO, UFW1V471MPD, and UKW1V471MPD1TD. Some look to be identical, yet somehow different?
  
• I am still a bit confused why 25V capacitors are not OK for a 24V setup, but the 16V capacitors are. But I can accept not understanding.
  

[Paul Birkeland]

The Nutube specifies 5V minimum for plate voltage, so perhaps it's more specific to the B1? 

You could stack together batteries to a much higher voltage than 25V, then regulate it down.  I wouldn't do this for the Quicksand though.

I think the 16V caps will be OK with the higher power supply voltage, as the DC voltage at those caps should be around 12V DC (and some AC will ride on them from the amp's output).  Do feel free to buy 25V caps for that position if you like. 

If you're going to hook the Quicksand up to a stack of 1.5V batteries that are supposed to add up to 24V, they will add up to more than 25V when fully charged.

[irishpatrick33]

The Nutube specifies 5V minimum for plate voltage, so perhaps it's more specific to the B1? 

You could stack together batteries to a much higher voltage than 25V, then regulate it down.  I wouldn't do this for the Quicksand though.

I think the 16V caps will be OK with the higher power supply voltage, as the DC voltage at those caps should be around 12V DC (and some AC will ride on them from the amp's output).  Do feel free to buy 25V caps for that position if you like. 

If you're going to hook the Quicksand up to a stack of 1.5V batteries that are supposed to add up to 24V, they will add up to more than 25V when fully charged.

The PASS NuTube B1 positively runs off 24V. Pete Millet's variant runs between 12-30V.

Now I understand the 16V cap situation.

Sorry to be a pain. May I ask why I shouldn't regulate down to 24V? That seemed like my ideal build. Also, any guidance on the 25V cap replacements?

[Paul Birkeland]

The PASS NuTube B1 positively runs off 24V.

What do you think happens at 23V?

Sorry to be a pain. May I ask why I shouldn't regulate down to 24V? That seemed like my ideal build.

1.  Straight batteries would probably sound better.
2.  Regulators get nice and toasty.
3.  You need extra voltage above the 24V to keep the regulator happy.
4.  You need to factor in some additional voltage headroom so that your batteries can run down a bit before the regulator drops out.

I don't know on the caps, just be sure the lead spacing and body diameter aren't a problem.

[irishpatrick33]

I don't know on the caps, just be sure the lead spacing and body diameter aren't a problem.

Could you possibly tell me exactly which caps were used for C9/C16, C13, and C8/C9? That would help me identify the suitable upgrade. Thanks.

[Paul Birkeland]

Here's an example of a part on the board.  You can see "FW" written on the cap, and "Nichicon" is written on the other side.  If you have a metric ruler, you can measure the lead spacing, diameter, and height of the cap.  That is enough to locate the part number.

For this particular cap, knowing that it's a Nichicon FW and a 470uF at 25V is enough to locate the exact part number. 

[irishpatrick33]

Here's an example of a part on the board.  You can see "FW" written on the cap, and "Nichicon" is written on the other side.  If you have a metric ruler, you can measure the lead spacing, diameter, and height of the cap.  That is enough to locate the part number.

For this particular cap, knowing that it's a Nichicon FW and a 470uF at 25V is enough to locate the exact part number.

OK, fair enough. I think I can figure out two of the caps. But the TDK cap is still a mystery. There is nothing on it other than 684. I am looking at multiple different caps: FG18X5R1H684KRT06, FG14X7R1H684KRT06, FK14X7R1H684K, FK16X7R1H684K, and FK11X7R1H684K. Some of these are different series, some I can't tell what the differences are other than shape... maybe?

[Paul Birkeland]

The TDK cap is a 0.68uF 16V X7R with 2.5mm lead spacing.