the CTH (Compact Tube Hybrid) Rev A thread... - Page 31

 

Or use a higher concentration alcohol. I use 70% USP isopropyl alcohol, aka rubbing alcohol, and I rarely have to use it twice. It's strong enough to remove paint.

 

Also make sure your toothbrush is clean. If you used it to clean your bicycle's rear cassette, then it's probably leaving more grease on the circuit board than anything. (speaking from experience  )

Most stores only carry 91% isopropyl alcohol. I have never seen anything stronger than 97%. Where did you find 99%?

You can leave it stand on the board for a short period to allow the solution to work. The key is to get the flux residual disolved into the liquid so that it can be poured off or wiped off/absorbed with a cloth or paper towel. If you used liquid flux in addition to the flux in the solder, it can take a fair amount of work to dissolve all of the residual.

As Kim pointed out, be sure to clean the toothbrush as well. The bristles can hold a fair amount of gunk. I actually use a couple of them during the process. Rotate them to keep them clean and effective.

 

+1 to that! I actually forgot this part. It might make a big difference. Although alcohol dries fast, so it might not give you much "soaking" time. Alcohol is, after all, a solvent. The idea is to dissolve the sticky stuff into the alcohol and then pull it away. Simply brushing will move it around and spread it evenly on the board, but it won't remove it. This is why contact cleaner is so effective in aerosol spray cans. It soaks the whole part, making the dirt drips away. The pressure of the spray helps dislodge and push away the rest.

 

So yeah, toothbrush might be good to dislodge rough stuff, but it won't remove it from the board.

You can say that again! That's the kind right there. And a gallon of it no less! 

 

Every hardcore bum in America is drooling at that sight... 

 

Seriously, after an initial soak and scrub you probably can pour it over and off the tilted surface of the board for final removal of just about anything.

Another satisfied customer! I finished the build (finally!) last night and had nice sound from the left, and a loud hum from the right. Turns out my wire at IR had broken during boxing it up. D'oh! Fixed that earlier today and now there's sweet music. First impressions are that it sounds wonderful! Have to roll some tubes but man, a revelation! Silky smooth, nice and detailed, not too warm. My only observation is that the gain is high for the headphones I've tried: I don't think I'll be listening much beyond 9 o'clock on the pot. That may be due to the headphones, they're old and probably not-very-good Panasonics. I'm starting to work on the wife to let me buy some new headphones :) And then I need to start thinking about the next project, of course
 

Once I've tidied up the build (and figured out a way to dril a 1" hole for the tube!) I'll post some pics.

Congrats mrhk13! It's one hell of a little amp. I just finished a another pimped CTH build. Yep, it's the same one I've been seeking troubleshooting help with on the last couple of pages. I picked up a Belleson 24V super reg and some Hovland caps for this build, and I made the error of building it first time with these parts. Right channel fine, no left. I start poking around months ago trying to figure out the problem, and in the process I shorted out a bunch of BJT's. Being stubborn, I spend a couple of months studying the circuit and tracking down the offending transistors (Q4*). I put in stock reg and caps, fired it up - right channel no left. I checked ICL, and I wasn't getting the output I should so I changed ICL. Right channel, no left. Frustrated, I pressed down on ICL and my left channel switched in!!! Hmmm. Powered down, flipped the board and re, re, re checked my joints. Damn. One pin of ICL I DIDN'T SOLDER! Can't tell you how many times I looked at that. Soldered, fired it up, all is well. I then proceed to swap in my new reg and caps one at a time. The circuit took them just fine.

 

So here's what I want to leave you with. If you're using a non-standard case and have the room, you MUST swap out the 24V reg with a Belleson. The sonic improvement is huge. With the Belleson and the caps, this little amp has push aside my Lyr with my HE-500's. Very, very, very good.

 

Did we ever get pics of your setup?

 

I usually rotate my amps about once a month.  Started using the CTH again yesterday.  Very satisfying indeed!

 

BK

Not yet - I'm waiting for some standoff's to arrive to anchor the board. Once I fasten it, I'll upload some picture. Yes - very very satisfying. A friend (LFF) just ordered a Belleson for his just completed CTH. Nice upgrade.

The one you want, is the SPJ78, 24V. Detail is increased, low's, mids and highs are quicker and more 'solid'. Essentially, the amp never starves in transients, and has the current 'headroom' needed to present a cleaner, clearer sonic image. Sound stage is improved - I believe largely due to the extremely stable/ripple free regulation. Yes - without a doubt. Truthfully, I always slightly preferred a stock CTH house sound over Sunrise, but now - well, let's just say that I'm constantly left wanting to hear more. At ~$60 it's not a cheap upgrade, but to me it was well worth it. I'm very interested in hearing your impression (and others), should you dive in.