4-channel Quickie

[marty51]

I intend a 4-channel Quickie for the mid & high of a triamp system.  I will make a new top plate from 2 Quickies with a single input and output for each channel (all I need).  Can I run 4 tubes from the battery packs for 1 Quickie?  Looking at the current draws, it appears possible (with obvious reduced battery life).  2 separate Quickies is an amp too far for the shelf.
Many thanks

 

[Paul Joppa]

You need a separate D-cell for each tube's filament.

You could use the smaller C cells, to more closely match the reduced 9-v battery lifetime when they are feeding four channels.

 

[marty51]

Thanks for your quick reply, Paul.  I was gifted a decent lab bench DC power supply recently so I assume I can use that for the B+?  Overkill, I know but a freebie.  In which case does the PJCCS do anything for me?
Really looking forward to trying this revered preamp.
Thanks

 

[Grainger49]

Marty,

Some of the magic of the Quickie is that it is battery powered.  There is no AC ever connected to it, it can't hum from the power supply.  Even a lab supply could introduce some hum.  And maybe not.

 

[Paul Birkeland]

Thanks for your quick reply, Paul.  I was gifted a decent lab bench DC power supply recently so I assume I can use that for the B+?  Overkill, I know but a freebie.  In which case does the PJCCS do anything for me?

The bench supply is probably OK for the B+.

The PJCCS is still a worthwhile upgrade. 

 

[marty51]

Thanks, all, for the replies.  This forum is what makes BH amps THE choice for the novice.  Only one way to find out - 2 Quickies ordered.

 

[marty51]

I've built one of my Quickies stock (with PJCCS) & put it the mid channel of a triamp system, sitting on some foam supports and connected with screened interconnects.  It works, at least it measures right and it plays music but with some issues. 
The one that concerns me the most is D cell life.  I lost left channel at 20 hours, one D cell down to 1.05V (other is 1.35V).  New Duracells - Costco's best.  Anyone ideas why one channel would have a shorter life?

Haven't formed an sonic impression yet because it's still too new but, for the record:

I have mobile phone interference - will try PJ's RF capacitor suggestion.  The intention is to put the guts of 2 Quickies in a bespoke single metal case later.
Very low volume scratchy noise from that left channel (not tube related) with shorted inputs.  Have re-flowed all joints.  Can't hear it from 300mm away so can live with it.  EDIT: This was RF noise from a MacMini next to Quickie.  Alu foil shield as temporary fix.
Microphonics are simply horrendous.  Piano notes audibly distort at higher volume with all 3 flavours of tube I have.  I will try the various fixes here but this might be the deal breaker for this fun little amp in my system.

Still looking for a 4 channel preamp solution with about 6dB gain.  Any recommendations for modifiable versions of other BH's?

 

[Grainger49]

The D-cells power the heaters.  The draw is predictable.  If you had bad life on one cell, it is most likely because it was weak to start with.

I don't remember if the D-cells are dedicated to a tube or used for both tubes.  Either way, it could be a very odd tube, drawing too much current.  But it was most likely a bad battery to start with.

 

[mcandmar]

I have had odd issues with that particular brand of batterys, i had one 9v suddenly drop to less than a volt, but it still created a circuit so the amp was working on reduced voltage, the rest died shortly after.  They don't make them like they used to..

 

[corndog71]

If you're getting a lot of incessant ringing then chuck the tube.  Buy a bunch of 3S4 tubes.  They're cheap.

 

[Doc B]

You could also try moving the preamp farther away from the speakers.

 

[Paul Joppa]

I hate to say this, but it seems Duracell batteries are made in China as well as in the USA. Some sellers offer both - the USA ones cost quite a bit more. The last time I looked, Costco was selling the Chinese ones.

It's only recently that I've heard anything bad about the Chinese batteries.

 

[marty51]

I hate to say this, but it seems Duracell batteries are made in China as well as in the USA. Some sellers offer both - the USA ones cost quite a bit more. The last time I looked, Costco was selling the Chinese ones.

It's only recently that I've heard anything bad about the Chinese batteries.

Aha!  Thanks Paul.  Since I live in Taiwan, no surprises where these local Costco Duracells were made.  They are US80 cents a pop here.  Perversely, the 9V cells are working out fine.

 

[Paul Joppa]

I was at Costco today (in North Seattle) and all the Duracells they had were "made in America". Perhaps I remembered wrong, perhaps Costco cleaned up their act, perhaps Duracell acted to protect their brand, who knows? But from now on I'm checking the fine print before I jump on a bargain battery!

Prices were 14 D-cells for $14.79, and 8 9-volts for $15.89

 

[marty51]

The 2 Quickies are up & running and they sound just wonderful.  I'd like to keep the battery concept but the above quality problems compound with both my Quickies in one chassis, quite apart from housekeeping 12 cells.  Yuasa SLA's are cheap here.  Would this idea work to provide the right voltages with 3 separate grounds?  The LM317 based reg boards have been suggested here before and at their price, not worth making oneself. Apologies for basic questions but as a mechanical engineer, I struggle with electrickery.

 

[Paul Birkeland]

Your drawing doesn't have separate grounds.  V1 and V4 will have filaments that sit at about 13.5V, V2 and V3 will sit at about 25.5V.  This is the bias applied to the tube itself, and when you try to put a cathode resistor in, you'll be providing a path to ground for battery current.

You'd need a separate cell for each 3S4 regulator, then a stack for the B+.  You might be able to find a filament transformer with four 5V windings, which would help get you where you need to go.

 

[mcandmar]

Or if you really want to stay battery powered use four 6v SLAs feeding into four separate LM317's.  Its going to get big and heavy real fast..

 

[Grainger49]

I'll throw some thoughts at you.

Dropping 12V to 1.2V will waste a lot of voltage and heat the regulator in doing so.  Maybe you can find a 3V SLA?

I tried floating the ground on a PAS-3 preamp and it didn't work.  Try it but be prepared to try a ground too.

Here is hoping it all works!