Charlize, with or without a pre?

[zacster]

I've got all the parts to build a Charlize amp and was wondering whether I should build it as an integrated, with an Alps Blue velvet pot directly to the amp, or should I use an active pre and bypass the Alps entirely. I guess I'll find out soon enough, but I was wondering what others have found, if anything.

It'll be mostly used with an iPod as input, and I've built a pair of cardboard Metronomes with Radio Shack drivers as speakers. The speakers will eventually get replaced with some real metronomes, but they'll have to do for now. This system is for my kids so it doesn't have to be perfect, but I do want it to be able to go somewhat loud so I don't hear complaints from them. I'm looking to get them away from my main system so I can use it!!

[serengetiplains]

Whether you need a pre depends on whether 1) you need voltage gain and/or 2) whether you need an impedance adjustment (ie, a buffer). If you need neither, search the Lightspeed thread. Smoking good passive pre, holy cow.

[Pano]

Does the Charlize have an option for higher gain? I should know, but I don't.

If so, you want to use it for iPod as a source. A 1V source like most MP3 players won't drive the inputs of the chip to full power, unless you use the option of more gain.

The gain is set by the ratio of the input to feedback resistors.

[Puffin]

I believe the Charlize is based on the 2020, as is the Audiodigit 2020. The gain is adjusted by the value of the resistors.

[vt4c]

One way of increasing the gain of Charlize is by changing the value of resistor, Ri; which is R371 and R372 on Charlize

The gain calculation is done as follows....

Gain = 12 (Rf/Ri)

Where Rf and Ri on the existing Charlize is 20K ohms

As the 2 resistors are in smd package, it will be abit tricky to change.

[zacster]

I "finished" it last night and have it on now and it sounds fine with the blue velvet pot as the only control, with a low output modded Toshiba 3960 as source. I'll still give it a try with my Aikido which is sitting right next to it for kicks, but since this is for a kids iPod hookup I'll use it as is when I'm done swapping around.

I still have to install permanent RCA jacks in it, the ones I have are PCB mount and the body isn't deep enough to mount on the wood box. The box came from a smoked Alaska salmon gift box.

And for anyone building a Charlize, follow the instructions on the speaker outputs. The square and circle solder pads are backwards on one side, but the picture on the website is correct. I turned it on and was listening for a short while when I was bothered by the fact that the sound was coming from behind me and I realized I was out of phase. I swapped the cable on one side and all is OK, but I still have to swap them on the inside now.

[KT]

Zacster, If you have no gain issues and can use either the pot or the preamp, I think you'll find a good tube preamp can raise the performance of the system up a whole level. I've used my Charlize with a tweaked out Cary SLP-94 and it sounds so much nicer than just the Charlize with a passive pot attenuator. I've also used Charlize with the Dave Slagle autoformers and that sounds great, too. Perhaps not as lush and lucid as the tube pre, but very soft, dynamic, and musical. Less of a resource hog, too - important if you listen to music in bed at night and end up leaving the system powered up until morning. Of course, if you're setting it up for the kids, maybe just using a pot is enough. It'll sound good enough that they'll be happy (unless they're starting down that dreaded audiophile path) and is a whole heck of a lot less fussy. Having said that, I found that the PEC carbon pots to sound very musical and I prefer them to most others I've tried, which include the Blue Velvet, Black Beauty, Noble, RadioShack Alps, and others. The stereo tracking is not always the best with the PECs, however, so it's sometimes a pain to get the initial setup right. Also, those tiny little green pots from Australia sound really good. Clean and slick sounding - not warm and lush like the PEC, but musical in a different way. My initial impression was that they were too quick and slippery sounding, but after a while I found I preferred them to the more sedate sounding Blue Velvet and Black Beauty. Could be a system thing. Best, KT

[zacster]

I put my Aikido in yesterday and it was better, a little more detailed and a lot more oomph. I have a Bottlehead Foreplay II sitting unused so I may hook it up with that for the kids, but I'd have to seal the insides on it first. With just the pot and an iPod as input it didn't go quite loud enough, although maybe that's a good thing. I set my son up with an amp and Murphy Blaster speakers a few years ago and guess what, he likes it LOUD, and he likes cranking his guitar up even louder.

The kids were happy enough with computer speakers so this will be light years ahead.

And another NYer, whereabouts? Brooklyn myself.

[vt4c]

Same observation here. ...Charlize will benefit using a line-stage especially a tube based line-stage.

Mine is hooked up at the moment using a 12B4 design and will probably try out using the #26 tube later on....

[KT]

Hi Zacster, I, too, live in Brooklyn... well, I lived in Brooklyn, anyway. I recently moved back to Seattle where I grew up. I lived in Willamsburg, 3 stops in on the L train (the Graham stop) for 5 years. That was after a 2 year stint in grad school in Rhode Island. When I was there I didn't hang out too much with other audio nuts, maybe a brief appearance at the AudioCircle New York meeting once, and I did work at In Living Stereo in Manhattan for about a year, but other than that my audio interested has been mostly a solitary and online pursuit. If I were still in NYC, though, I would have loved to have meet with you to compare Charlizes. I do miss New York. Best, KT