Keeb's Fender amp

[cactuskeeb]

This amp cost me a lot of money to learn how to build but it was worth it.  I'm finally ready to oblige those who, months ago, requested recordings of the amp at "full" volume (right now, that's "3" and "5", respectively, for the Normal and Vibrato channel).  Stay tuned, while I find the time this week to try and work through a few more recording issues before posting some simple riffs and bits of blues solos.

[Poster]

Winning.http://www.youtube.com/watch?v=HpntNDAYltM

[sour d]

Winning.http://www.youtube.com/watch?v=HpntNDAYltM

I was so buzzed I watched the whole thing. Where do I get pants like that?

Cactus, love the pics. Are the blue caps NOS?

[cactuskeeb]

Winning.http://www.youtube.com/watch?v=HpntNDAYltM

Air Supply is really good.

[cactuskeeb]

Winning.http://www.youtube.com/watch?v=HpntNDAYltM

I was so buzzed I watched the whole thing. Where do I get pants like that?

Cactus, love the pics. Are the blue caps NOS?

I think there's a chance at least one might be NOS.  Problem is, the visual distinction between a lot of my new old stock parts and their used counterparts has blurred significantly, due to my having swapped out so many different parts, over and over again -- in a lot of cases, the same part may have been soldered, desoldered and removed, and then later on re-soldered. 

But this is kind of beside the point, which is: *non-electrolytic* caps that are NOS do not provide any benefit over those that are not NOS.

[Walker done done]

Winning.http://www.youtube.com/watch?v=HpntNDAYltM

I was so buzzed I watched the whole thing.

That's gotta be the trick because I'm at work and there's no way I could make it through more than 90 seconds.  That actually hurt.  I was having a great day too.

[Happyorange27]

PUKING!

[sour d]

But this is kind of beside the point, which is: *non-electrolytic* caps that are NOS do not provide any benefit over those that are not NOS.

I wasn't really thinking about the sound of the amp, I was thinking how much money it would cost to replace everything in a deluxe, and I know people charge more for NOS stuff. I really want to start an amp project soon. I have a 1970 conn organ and I was thinking of tearing into that.

[cactuskeeb]

But this is kind of beside the point, which is: *non-electrolytic* caps that are NOS do not provide any benefit over those that are not NOS.

I wasn't really thinking about the sound of the amp, I was thinking how much money it would cost to replace everything in a deluxe, and I know people charge more for NOS stuff. I really want to start an amp project soon. I have a 1970 conn organ and I was thinking of tearing into that.

The cost of blue molded caps is ridiculously high right now.  People are making them out to be more than they are: just a really durable film and foil capacitor.  To be perfectly honest, I haven't noticed any difference in sound using different types of capacitors.  The only thing that really seems to make a difference is changing the values of the resistors in circuit; and perhaps three or four places where the value of the capacitor makes a huge difference.  Anyway, if you're going to start an amp project, I recommend paying a lot for really good resistors, so that you know they are not going to drift or whatever: it's the only way to have any control over the circuit.  Don't get NOS carbon comp.  Get Riken carbon film.


EDIT:  Actually, I really don't know what I'm talking about.  Best to do your own research.  My amp now has parasitic oscillation(s) (sounds like there's a mosquito making noise on top of certain notes) -- I must be doing something terribly wrong at this point.  I think it was a bad idea to swap out the 25uf/25vdc small electrolytic caps for a non-polarized 20uf...kind of made the tone very glassy, and with too much touch-sensitivity: I swear I could dig in with the pick and cause a +20dB, which my speaker really didn't like.  Also, I can't figure out why one power tube socket always biases lower than the other (like, a matched pair of 6v6's will bias at 17.5 and 23.0; and it's the same thing no matter which tube goes in the slot closest to the rectifier.  I probably need to check voltages or something at this point.)

EDIT #2:  Maybe I do know what I'm doing, b/c I fixed all the issues earlier today and it only took me about an hour.  Well, all except for the power tube bias issue.  But I'm sure if I just reflow the solder joints connecting the primaries to the pins on the output tube sockets, as well as the filament wires, I'll (probably) fix this issue as well.  

Also, for some reason my amp sounds totally different when it's sitting (normal-like) on the floor, as opposed to tilted back slightly whilst leaning up against something.  I know this normally has an affect on sound but I think in my case, tilting the amp leads to a shit ton more vibration in the chassis and fucks with the preamp tubes (the sockets are old, loose, and need to be replaced).

And I think I may put back the non-polarized, 20uf/50vdc caps where I re-installed the standard, polarized 25uf/25vdc ones.  Why wouldn't you use a non-polarized cap when you have them available?  Btw, these particular ones cost me fifty dollars each -- see: http://www.tedss.com/item.asp?id=2020000984 -- and, originally, I was going to install them as passive crossovers for my car's rather cheap dashboard speakers but used some "snake-oil" japanese ones instead, for that project.  Plus, they're the same size as the old-school dual can caps that are original equipment in all blackface amps.

[cactuskeeb]

Chassis update:
As of April 1st, it's looking like this:








No problems at all other than the intermittent, relatively hushed rattling noise that I really hope is just a preamp tube, and not the speaker or circuit-related.  Fyi, if you've never done it, you cannot fully appreciate the amount of time and effort it took to set all those components right and make sure they held still while the soldering process was taking place.  It takes *hours*, literally, to change just a few components (and in the process, making sure they conform to component board placement etiquette).

P.S. I set up the mics tonight, hopefully to do some recording tomorrow:

[Happyorange27]

This is spectacular. I can only imagine the intensity of point to point. Even with a perfectly laid out pcb mods can take time, so your amp would multiply that many times over. Looks good man.
Rattles can be frustrating to diagnose. Hope you find that soon. 

[cactuskeeb]

This is spectacular. I can only imagine the intensity of point to point. Even with a perfectly laid out pcb mods can take time, so your amp would multiply that many times over. Looks good man.
Rattles can be frustrating to diagnose. Hope you find that soon. 

Yes, the work can be intense.  I learned about soldering techniques from Nasa documents available on the web and from extensive discussions with a few amp builders.  The real key is to create a solid mechanical connection first, without having applied any solder yet, understanding that solder is not what creates the connection but rather what holds it in place by being the glue that surrounds and solidifies it.

I found the main culprit of the rattling -- the preamp tube in V1 -- thank goodness.

[Poster]

The next evolution to my super deluxe is going to be pretty dramatic.

Popping out the amp and tank, sticking it inside a head enclosure from Mojo.

Going to get a dove tailed pine 2x12 to go inside my combo road case.

I figure either the head with fit in there too, or it wont, in which case, Ill grab a gator mesa spec head road case.

I cannot fucking stand these combo cabinets anymore. No they dont sound that bad, but dayum a closed back, pine cabinet sounds so much

better.

[cactuskeeb]

I was playing the amp today and realized there is simply too much gain.  If I turn the volume on the normal channel past three (three is actually the perfect stage volume, believe it or not) the amp shows itself to be completely unstable and -- while I can't put adequate words to the sounds it makes -- suffice it to say, it craps out.  The same thing happens past 5 on the second, "vibrato" channel.  I learned that I can manipulate the point at which it actually starts to crap out by turning down the mids.  The mids control is itself kind of a gain control, as you turn it up...more gain.  But the output tubes are biased at 23-26 mA on the Weber "bias rite" meter (people call it the "bias wrong" for good reason: for the actual bias in my amp is probably more like 35 mA, roughly, per tube).  This all boils down to some pretty cool breakup at just the right volume level.  I've never played through an amp so small that sounds so wide.

I probably should take steps at this point to lower the gain, because it's not cool to have an amp that can crap out suddenly if you're not careful with the vol. and tone controls.  However, I really like how it sounds right now.  I know I've said that before but right now we're talking about a whole other level of tone.

Oh, yeah, and sorry about not having a recording to offer, yet.  It's just kind of hard to do anything other than stand there and play for a couple hours.  I'm enjoying it so much I don't want to have to mix in the tediousness of all the steps I have to take to lay down some tracks in my very amateur, home-recording kind of way.  But I've got make myself understand -- precisely by doing more recording -- that once i have enough experience with it, it will start to become much less tedious (and less frustrating).