Shopping & Learning: starting DIY on guitar amps

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Re: Shopping & Learning: starting DIY on guitar amps

Post by 1946dodge » Mon Jul 28, 2008 7:00 pm

Musicmaster Bass Amp in the background.  It sounds great, but has developed a wicked, wicked bad hum.  The plug is bad, which I hope is the problem, because that's easily fixed...
If it hums, you may only need Filter caps. There are probably 4 of them and they are big and easy to replace if you can solder. But you got to put them in with the right polarity too.

Are you sure one of your tubes isnt crappy? Bad ones can make it hum too.
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Re: Shopping & Learning: starting DIY on guitar amps

Post by bish » Tue Jul 29, 2008 3:58 pm

I have another amp DIY question. I'd like to replace the cheap tubes that came in my Blackheart Little Giant with the same type but that are of better quality and see how big a difference it makes. I'll need to get one 12AX7 preamp tube and one EL84 output tube. If I replace the tubes with the same type do they need to be re-biased? Also any recommendation on the brand of tubes I should try?

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Re: Shopping & Learning: starting DIY on guitar amps

Post by Jay » Tue Jul 29, 2008 4:30 pm

The new Tung-Sol 12AX7s sound really good and I've got old Mullards, Amperex, and Telefunken's to compare them to.  There are differences but honestly I don't think they sound noticeably "worse" in any way.  The only problem is that they're big and sometimes don't like to fit in the sockets with the little metal shield around the base that the larger metal shields attach to... one like in most vintage Fender amps.

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Re: Shopping & Learning: starting DIY on guitar amps

Post by bish » Tue Jul 29, 2008 8:08 pm

Thanks for the info. I may end up spending a little bit more on tubes since it's only those two and I'm not gassing for anything else at the moment hehe.  I'll take a look at the ones mentioned and see what I can find. I'm really enjoying my Little Giant at the moment as is but I''m really curious to see how the tone changes with better tubes. Someday I may even get the courage to mod the thing hehe.

Thanks again,

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Last edited by bish on Tue Jul 29, 2008 8:11 pm, edited 1 time in total.
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Re: Shopping & Learning: starting DIY on guitar amps

Post by bish » Tue Jul 29, 2008 11:38 pm

Well after a little research I decided to order a Tung-Sol 12AX7 and a JJ EL84 both of which seem to get pretty good reviews and recommendations, the JJ was also one of the only ones that I could order singly. Came out to about $35.00 total with shipping. I decided to forgo getting any NOS tubes at this point since it will be my first time re-tubing and I am accident prone :P My nickname in college was "tripper" as in Jack Tripper heh.

I'll post how it goes once they arrive :)

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Re: Shopping & Learning: starting DIY on guitar amps

Post by noirengineer » Wed Jul 30, 2008 7:48 am

i love these chats

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Re: Shopping & Learning: starting DIY on guitar amps

Post by bish » Wed Jul 30, 2008 9:40 am

øøøøøøø wrote:should you happen to find you dislike the JJ EL84, you're out, what, 12 bucks?  Hardly a high risk purchase.  ;)
Exactly why I went with the JJ, and as I said it was also the only one I found available singly and not as a matched pair set.

And of course reviews are completely subjective and prone to all sorts of negative and positive factors. But I also don't just read one review or forum post or whatever and take it at face value. I try to look at as many reviews as I can find and see if there is a general consensus. In the end its just a way to get started and then create your own opinion.

One interesting thing I found, when looking at some online tube merchants they had a choice for each power tube. Early, Average, Late Distortion, some had it listed as High, Medium and Low Distortion. I was surprised that they got that specific about each individual tube or is that just blowing smoke?

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Re: Shopping & Learning: starting DIY on guitar amps

Post by øøøøøøø » Wed Jul 30, 2008 9:48 am

bish wrote:
øøøøøøø wrote:should you happen to find you dislike the JJ EL84, you're out, what, 12 bucks?  Hardly a high risk purchase.  ;)
Exactly why I went with the JJ, and as I said it was also the only one I found available singly and not as a matched pair set.

And of course reviews are completely subjective and prone to all sorts of negative and positive factors. But I also don't just read one review or forum post or whatever and take it at face value. I try to look at as many reviews as I can find and see if there is a general consensus. In the end its just a way to get started and then create your own opinion.

One interesting thing I found, when looking at some online tube merchants they had a choice for each power tube. Early, Average, Late Distortion, some had it listed as High, Medium and Low Distortion. I was surprised that they got that specific about each individual tube or is that just blowing smoke?

-bish
Good!  :)

As for the "early, average, late" distortion thing, I don't have an opinion, but I tend to regard such things with a certain amount of skepticism.

I'd have to know what they were measuring and selecting for.

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Re: Shopping & Learning: starting DIY on guitar amps

Post by noirengineer » Fri Aug 01, 2008 7:28 am

Question:

*  what temperature(s) are ideal to set the iron at when soldering audio components ?

*  What type and diameter solder?

*  Heat Sink and strain relief... thoughts?
add a drop of hot glue or silicone to the 'hot' connection to insulate it and keep it from shorting to the shield or breaking. 
Now your cable will probably last a lifetime.  I recommend Canare and Mogami bulk cable, good stuff!  I like Neutrik connectors.

???

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Re: Shopping & Learning: starting DIY on guitar amps

Post by Maggieo » Fri Aug 01, 2008 7:30 am

The first thing I solder when I get my iron is going to be my Z Vex SHO, which self-destructed under the assault of my Vibro Champ.  Seriously.  A wire on the switch came undone, apparently from the vibration coming from the VC.  :wtf:
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Re: Shopping & Learning: starting DIY on guitar amps

Post by Orang Goreng » Fri Aug 01, 2008 7:32 am

øøøøøøø wrote: Step one: You hold the cold end.  :)  Just kidding.
Reminds me of this sign, popular enough to hang in every damn lab I ever worked:

Image

Image
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Re: Shopping & Learning: starting DIY on guitar amps

Post by Orang Goreng » Fri Aug 01, 2008 9:03 am

øøøøøøø wrote: and especially DO NOT use acid core solder.  That stuff is for plumbing work.
You might be surprised how well it can perform sometimes. I used to work with implanted electrodes, and those things pretty much have to be surgical steel in order not to react with body chemistry (and consequently give off nasty ions that might interfere with normal physiology). I had to use a corrosive to solder my electrodes to the leads, as you can't really solder steel any other way. I got perfect recordings from those things.
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Re: Shopping & Learning: starting DIY on guitar amps

Post by øøøøøøø » Fri Aug 01, 2008 9:08 am

Orang Goreng wrote:
øøøøøøø wrote: and especially DO NOT use acid core solder.  That stuff is for plumbing work.
You might be surprised how well it can perform sometimes. I used to work with implanted electrodes, and those things pretty much have to be surgical steel in order not to react with body chemistry (and consequently give off nasty ions that might interfere with normal physiology). I had to use a corrosive to solder my electrodes to the leads, as you can't really solder steel any other way. I got perfect recordings from those things.
Cool!  But I'd still advise against it for general purpose use! 

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Re: Shopping & Learning: starting DIY on guitar amps

Post by Orang Goreng » Fri Aug 01, 2008 9:10 am

Sure. My tech was horrified I used the stuff, BTW. But I learned it from another neurophysiologist, and it turned out to be common practise. I later switched to electrodes with crimped-on contacts though. In all honesty, those were a lot more consistent.
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Re: Shopping & Learning: starting DIY on guitar amps

Post by noirengineer » Fri Aug 01, 2008 10:19 am

øøøøøøø wrote: Answer to question one:  It depends.  The answer is "hot enough to get in and out quickly, but not so hot as to overheat the component."  There are two ways you can melt a component.  One is to have a pretty-hot-but-not-hot-enough iron on it for a long ass time, and the other is to have the iron so hot you instantly vaporize it.  You want to be somewhere in between these two extremes.  Fortunately, that's a pretty wide window and a large margin for error with MOST components.  I usually set my iron right in the middle of the gauge for 90% of work.  For things with large surface areas that take more to heat, I might bump it up a little.  For PCBs with fragile traces, I might bump it down slightly.  For chassis grounds I crank it all the way up, but even that isn't enough to get a good chassis ground always. 
I have a radioshack soldering station with digital temperature meter..
It's basically a fahrenheit temperature reading on it..  what temperature is
a good starting point (in fahrenheit)?

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