Tweed Champs what do you like?

[Mark]

What models do you like and why?

http://www.freeinfosociety.com/media.php?id=3281

I have a Kendrick Roughneck which I've modified.

[IMG766]http://i149.photobucket.com/albums/s69/ ... eck009.jpg[/img]

[IMG766]http://i149.photobucket.com/albums/s69/ ... eck003.jpg[/img]

The mods consist of getting rid of the 470K input resistors (one with treble boost/shunt on it) I went back to stock as I didn't like the tones and having half the input signal made the amp noisy.

I wanted a bit more volume so I stuck with the 6L6 and the 5AR4, this is an issue as the screen current causes excessive compression in the pre-amp, basically I used a 47uF filter cap on the node feeding the output transformer and 47uF on the node feeding the screen grid, I also used a 1K screen limiting resistor for good measure. I did try lowering the 10K screen power supply resistor, but the voltage was more than the various tubes I had could bear.

I also like Ted Weber's Silver Ten in this amp, it certainly isn't Celestion like, but it does have a lot of bottom end which the amp needed. It sounds more balanced.

I have had a lot of problems with Champ volume pots which incorporate the power switch, the wiper on the pot tends to go. I have just put in a Ted Weber 1M volume pot/switch in the amp after a couple of Alpha pots that went bad. So far it is going okay and I like the 30% taper it does get loud quick but I don't use a bright cap as I did with the Alpha pots.

I also used an output transformer with a 5K primary which gave the amp an 8 watt output. I was rather keen on the amp at this stage till I realised the power transformer was running too hot. The amp was a bit louder than a stock Champ, but it sounded quite a bit fatter and warmer (could be the speaker too). It did occur to me to get a bigger power transformer, but even after careful measuring the transformer still too big for the cab and chassis.

Oh yeah I also used a grid stopper on the output tube which helped the amp from becoming too bright as it distorted.

Due to the power transformer it is back to the drawing board on this one. I'll see what I can do with the stock 5Y3 and a 6V6. I'm also considering adding an extra stage of filtration to remove excessive mains hum.

Again any thoughts?

[Mark]

I should point out the beauty I see in the Champ is it simplicity.

It is the perfect platform to learn about amps, and this should not be confused with building an amp.

The Champ has all the parts any other amps does (with the exception of the tone stack of course) and one can hear differences with very few component changes.

One of the experiments I've conducted on the Champ was coupling caps. I tried out a five different caps in my amp to hear tonal difference, these caps were 715's, Sozo stock mustard, Sozo Blue, Jupiter yellow and Jupiter red caps. I heard absolutely no difference between these caps. I had a panel made up with a switch to instantly switch caps into circuit. I also used a recorded source and played into the amp, I recorded the results to allow comparison. I heard no difference between recorded results and the results through the speaker at the time. Which is to say there was no change in timbre at all.

I still don't know if caps make a difference in other amps, but there isn't a difference in Champs, perhaps there are too few caps in the amp to influence the tone of the amp?

[IMG:766:1024]http://i149.photobucket.com/albums/s69/ ... CN5058.jpg[/img]

What I found interesting throughout this whole process was how my picking produced subtle tonal differences. I dare say this in itself was worth experimenting.

Sorry if I am banging on about this but I think it compliments the other areas in these forums.

[martin manning]

I should point out the beauty I see in the Champ is it simplicity.

It is the perfect platform to learn about amps, and this should not be confused with building an amp.

The Champ has all the parts any other amps does (with the exception of the tone stack of course) and one can hear differences with very few component changes.

No PI, or cathode follower (each of which make their own contribution to the tone), and it is single-ended, but I take your point. Interesting that you can't hear any difference in the different caps. I'd have thought that such a simple circuit would show it, but perhaps it is as you suggest and the signal has to pass through a number of them to notice the effect.

[echuta13]

When I was playing with a 5f2a Princeton I had to change the value by quite a bit to make a noticeable difference (everything else being much too subtle). Going from a .022 to a .0047 on the first coupling cap focused the sound and shaved off some of the bottom. I don't think you'd be able to hear much of a diff if you were rolling from .047-.01.

[brewdude]

Funny, I have had a very different experience regarding different caps in a simple SE build. While I was not as scientific, I definitely perceived a difference between Mallory 150, 715 Orange Drops, 6PS Orange Drops and standard SoZo's. I have that I like the 6PS caps best, but I was too impatient to let the SoZo's reach the recommended burn in period.

[Mark]

Thanks for the replies. I did want to take a methodic approach to cap rolling as people (as far as I can tell) change the caps and remark that there is a subtle change.

When purely playing I had a bias towards Jupiter red caps, I thought they had a bit more chime, but using a recorded input and finally being very exact on where and how I struck the string I found the recording was giving me the real result.

Martin agreed a cathode follower does impart a certain sound upon an amp, I can't say I studied the different sounds of PI stages.

The beauty of the Champ is you can study the effect of the power supply on the tone of the amp which is often ignored. The effect of filtration upon the amp, how the screen current of the output tube effects the power supply performance, the list goes on.

It's a great first stop on studying amps.

[rp]

What models do you like and why?...I'm also considering adding an extra stage of filtration to remove excessive mains hum. Again any thoughts?

I like the absolutely stock 5F1, with the low filtering. I build three neither with any hum. Both were my own PTP layout. I build a 5C1 too I posted a long review on it, check my back posts, also posted on my 5F1's. I can hear cap swapping. I settled on NOS moldeds on my combo cab 5F1 just because they gave the richest 3D sound. IME It's important to keep the cathode resistor around spec and the plate V at around 370 in a 5F1 for best tone, try differnet tubes (helps to have a box of NOS pulls ) to get the current and V right rather than using a resistor above 560, 620 tops IME. Different trannies matter, as I've said before I like the Allen just cause it keeps the Fender sound. My 5C1 with the Edcor doesn't sound anything like a Fender, more like a tiny Hiwatt.

Yeh the orig style PTs like Mojo's run real f'ing hot especially in a combo. Meh, so did the originals for 60 years. Wouldn't worry, if it fries in 10 years you are a DIYer and it'll give you something to do. Pretty sure I used Hammond 372X in my 2 champ heads and they're cool and chill.

[Colossal]

@Mark: Great thread! Very cool to hear your observations on cap swapping.

@RP: I was going to ask some questions about your 5F1 but found your thread in a search. Very nice amp!

[Mark]

Feel free to put links up to other relevant Champ threads. I'm trying to find time to compare the two output transformers I have. Then I'll be able to post more stuff on the Roughneck/Champ.

The Champ sound on Hotel California is a great tone, I won't put a link up, as it is a long song for a brief passage.

http://www.youtube.com/watch?v=0Xuh0bLE6MQ

http://www.youtube.com/watch?v=G8MzmN0YNuI

http://www.youtube.com/watch?v=aur-k26c_7A

[rp]

There's a link here to my 5F1 combo:
http://ampgarage.com/forum/viewtopic.ph ... ms+welcome

and the trouble the combo gave me:
http://ampgarage.com/forum/viewtopic.ph ... e++isolate

Now I want to build an other Champ. Love building Champs. If I was rich I'd build them and give them away!

[Colossal]

Thread candy

[Mark]

That is a nice looking amp!

I've just A/Bed the rewound Kendrick O/P with a Martin Kell O/P transformer. The Kell transformer smashed the rewound Kendrick one in almost all areas.

The wife was right, size matters!

[IMG766]http://i149.photobucket.com/albums/s69/ ... CN5061.jpg[/img]
[IMG766]http://i149.photobucket.com/albums/s69/ ... CN5060.jpg[/img]

I've had another listen to the amp and this time I used my Strat. The stock transformer isn't without it's charm though I think it would be better to start with too much bass and cut it back with circuit changes rather than trying to boost what you haven't got.

Champs can sound thin, my amp is telling me it isn't the 10" speaker it is the transformer, the moral of the story being use a output transformer with a better bass response before looking for a speaker that will give you the desired bass response. Get a better output transformer and then look at getting a bigger speaker.

Aside I've noticed the word oversized appears lot on Mercury's site in relation to Champ output transformers.

[Colossal]

Aside I've noticed the word oversized appears lot on Mercury's site in relation to Champ output transformers.

Definitely makes a difference. A lot of these old amps have rather anemic OTs. The designers of Olde probably dimed the first amps and said, oh, that's horrible, why would anyone want to do that? and also built for a price point. I generally upsize my OTs and you can hear the difference for the better IMO. Nothing kills inspiration like an amp with no low end and shrill, coffee-can mid/highs.

[rp]

Yeh but you can overdo it with big/better iron. It's getting just the right thing that's hard, at least with limited funds and not wanting to chew up a chassis. My 5C1 w/ the Edcor sounds amazing but nothing like a Fender, it's all stock w/ NOS caps so it's got to be the OT doing all the tone difference.

Ever install a tranny you hate? I find choosing OT's to be the most aggravating part, as again with limited funds it's just educated guessing and hoping for the best. Since RJ's stopped selling I've been racking my brains over Rocket OT's and now a future 5B6. And now I'm in Euroland with diff options and limitations.

[Colossal]

Yeh but you can overdo it with big/better iron. It's getting just the right thing that's hard, at least with limited funds and not wanting to chew up a chassis. My 5C1 w/ the Edcor sounds amazing but nothing like a Fender, it's all stock w/ NOS caps so it's got to be the OT doing all the tone difference.

Good points. I think it's important that you pointed out the distinction that I think a lot of people get hung up on. If you change an amp's spec and it stops sounding like a Fender or whatever, then the resulting tone is either better or different but equally appealing to your ear, or you're dissappointed that it doesn't sound like a Fender. So I think there is a cognitive dissonance in the argument about tone. If I were making something like a Champ but a variant, I would likely upsize the OT (within reason) because I prefer a well balanced sound and have found the OT plays a distinct role in that equation. But if I wanted exact Champ sound, I would buy clone iron and my tonal bias would be selecting for the kind of tone that that choice of iron gives.

I think RJ's goal for instance with the Eagle and Eagle Supre projects was to take that fundamental Champ foundation but address the low end and try and get more of the recorded iconic sound live (more girth, body) so you can have your 5W and crank it too.

But that said, a straight-up Champ can sound amazing. Check out Greg V's demo of Tungsten's Mosaic (5F1 clone). Great playing.