Unexpected N.A.D.

[kbp810]

Been contemplating picking up a little 5 watt for a while now; going through my typical internal struggle between building one, buying one, or going all out and buying something of the bow-teek variety...

 

Then earlier today I happened to stumble across a '66 Black face Champ, and pulled the trigger.

It is in really good shape, with the exception of the on/off toggle - looks like someone had replaced it at some point for reasons unknown, and they did a semi hack job of it.

Cord has been updated to a 3 prong, and the speaker does not appear to be the original (and I'm unsure of what's actually in there at the moment)

 

Has a pair of RCA 6V6's and a "Peavy" labeled 12ax7 in place

 

At half volume playing my 575 it sounds like an absolute dream! At higher volume I start to hear some nice smooth breakup, but then the speaker starts to flub out and sound scratchy... I plugged it in to a 2x12, cranked it back up a bit, and it sounded pretty gosh darn groovy.

 

So I think a replacement speaker is in order, any other champ owners here have a good speaker recommendation?

 

[tulk1]

Why change the speaker? Others may verify or call me crazy. But that looks to be an unbranded Jensen. Maybe just get it reconed? Oh, and what a score!

[FredZepp]

I can see why you bought it... very nice old Champ.

 

I am thinking about another speaker for my Vibro Champ, so it will be interesting if you change it....

[Gitfiddler]

Nice unexpected grab. To me, all Champs are cool. I have an emotional attachment to them since my first amp at age 13 was a new Vibro Champ.

 

Anyway, if yours has an 8" speaker, check out the variour Weber models. They get great reivews, expecially their Alnico model.

 

I put a THD 10" in my Champ II that sounds pretty darned good too. You've already discovered the Champ secret however, by connecting it to an extension speaker cab. Those things get angry real fast...and sound incredible in the process.

[kbp810]

One quick edit... it's an RCA 6v6 and an RCA 5Y3 (not two 6v6's oops on that earlier mistype)

 

Also, the OT appears to be the original... which I believe means it's a 4ohm out (3.2). The speaker in there now looks to be an 8ohm, that could be part of the problem as well.

 

Perhaps someone can fact check me on that though before I jump the gun on a 4 ohm speaker.

[slider313]

Nice amp. You need a 4 ohm speaker.

[kbp810]

Nice amp. You need a 4 ohm speaker.

Thanks for confirming!

 

Just placed an order for a Weber 8s Alnico 4ohm

[slider313]

Why change the speaker? Others may verify or call me crazy. But that looks to be an unbranded Jensen. Maybe just get it reconed? Oh, and what a score!

 

The 328 code on the speaker makes it a Utah. The following digit "4" makes it 1964 and the next two "29" the week of the year. Many old Champs have been fitted with an 8 ohm replacement speaker which robs the amp of output and tone. Another important fact; I just worked on a Champ Saturday; is the bias on the single output tube. The amp I serviced was running the 6V6 @ 41.5 ma, which sounded ok, and is perfectly within range. I tested eight NOS 6V6's in the amp through my meter. They ran from 43 ma - 46.5 ma on average with one Sylvania 6V6 GTA coming in at 49.5 ma. The Sylvania 6V6 GTA sounded best with a Sylvania 6V6 GTY running 46.5 ma coming in a close second. These amps also need a nice old stock 12ax7. All the new production 12ax7's brought the volume down quite a bit. Remember, the 12ax7 is a dual triode and, in this amp, one half of the tube is used for your input signal and the other half drives the power tube. Strong tubes are very important in any tube amp but more so in an amp with only three tubes.

[kbp810]

The 328 code on the speaker makes it a Utah. The following digit "4" makes it 1964 and the next two "29" the week of the year. Many old Champs have been fitted with an 8 ohm replacement speaker which robs the amp of output and tone. Another important fact; I just worked on a Champ Saturday; is the bias on the single output tube. The amp I serviced was running the 6V6 @ 41.5 ma, which sounded ok, and is perfectly within range. I tested eight NOS 6V6's in the amp through my meter. They ran from 43 ma - 46.5 ma on average with one Sylvania 6V6 GTA coming in at 49.5 ma. The Sylvania 6V6 GTA sounded best with a Sylvania 6V6 GTY running 46.5 ma coming in a close second. These amps also need a nice old stock 12ax7. All the new production 12ax7's brought the volume down quite a bit. Remember, the 12ax7 is a dual triode and, in this amp, one half of the tube is used for your input signal and the other half drives the power tube. Strong tubes are very important in any tube amp but more so in an amp with only three tubes.

As always, thanks for the input

 

I'll have to keep an eye out for a Sylvania 6V6 GTA and give that a try

 

I have a few NOS/ANOS 12ax7's to play around with, but I think a Telefunken smooth plate will likely find it's home here.

[slider313]

It's not the brand but how much current draw the tube has. It just happened to be the Sylvania that ran a bit hotter and sounded better. Do you have a bias meter? If you want I could check my other NOS single 6V6's and see if I can find one that's running hotter than most.

[kbp810]

It's not the brand but how much current draw the tube has. It just happened to be the Sylvania that ran a bit hotter and sounded better. Do you have a bias meter? If you want I could check my other NOS single 6V6's and see if I can find one that's running hotter than most.

Yeah, I think that was a tube marketing brainwash moment I just experienced - I understood the point you were making about the current draw, yet my brain still only processed "The Sylvania 6V6 GTA sounded best"; and of course I realize even amongst same tube brand make and type it's going to vary.

 

I do have a bias meter (well, just one of those octal socket rigs running to my multimeter), I'll cycle through a few of the NOS singles I have on hand.

[slider313]

Yeah, I think that was a tube marketing brainwash moment I just experienced - I understood the point you were making about the current draw, yet my brain still only processed "The Sylvania 6V6 GTA sounded best"; and of course I realize even amongst same tube brand make and type it's going to vary.

 

I do have a bias meter (well, just one of those octal socket rigs running to my multimeter), I'll cycle through a few of the NOS singles I have on hand.

 

 

You want to find a 6V6, for this amp, that runs between 45ma and 50ma for the most punch and volume.

[kbp810]

You want to find a 6V6, for this amp, that runs between 45ma and 50ma for the most punch and volume.

Got the Weber yesterday, along with a few extra spare tubes I picked up, RC2 I bought from Brent, and a PSPIII DVD - maybe not as exciting as a new Heritage guitar arriving at my doorstep, but still pretty cool to have everything all arrive at the same time.

 

Threw the speaker in... changed out the 12ax7 with the Telefunken SP... cycled through a few RCA's, found one measuring upwards of 48ma... buttoned her all back up... speaker cable in, guitar plugged in, power on... chord strummed... and

 

Huge improvement on tone and volume, it really sounds fantastic!

 

-side note: upon removing the old speaker, the cone actually seemed to be in good shape... I didn't notice this before, but the neg side was really soldered poorly to the terminal, it was literately hanging by a thread. With this in mind I don't think it was entirely the speakers fault after all; between being 8ohm and having a bad connection, I could see why it was sounding less then stellar... so I'm thinking about maybe putting it back in service by way of building a 5F2 to pair it with.

 

 

 

[FredZepp]

Sounds like a great day....

 

That speaker just looks like it can put out some nice tone... very cool upgrades in a cool amp.

[Jazzpunk]

575+Champ= Awesome! Congrats

[brentrocks]

That lil amp is BA!!!