Fender Champion 600

[tot_Ou_tard]

Sweet, sweet, sweet. Thanks Spud!

Someday I'm gonna upgrade the transformer on mine.

[tunghaichuan***]

Someday I'm gonna upgrade the transformer on mine.

I was just in Guitar Center today and happened to look in the back of the cabinet. There is not a lot of room for a new OT. I doubt if a Hammond 125CSE would fit in there. If I had to guess, I would guess that the mounting centers are 2 & 3/8", but you might want to measure for yourself.

One OT that might work is the Fender Champ 12 replacement OT. It is a 10watt unit that has 2 & 3/8" mounting centers, but it is about 1" taller than the stock OT. It also only has an 8ohm secondary, so you'd have to find an 6", 8 ohm replacement. It is also kind of expensive, about $40-$50 IIRC.

Another OT option is this one:

http://store.triodestore.com/tfchxfwi48oh.html

It has a 4 ohm tap and an 8 ohm.

Finally there is this one:

http://www.turretboards.com/valve_ju...placement%20OT

Again, kind of pricey, but it is a Heyboer, so it will sound good. It has 4/8/16 ohm secondaries. It it is billed as a Valve Junior replacement, but with the 6.6k primary, it is more suited for use with a 6V6.

Let me know if I can be of any help when you decide to change out your OT.

tung

[tot_Ou_tard]

tung,

I'd love to hear more about how OT's affect the sound. I have no experience & find it difficult to imagine what they would do.

What exactly does a tap mean? Are these wires that one needs to solder onto a jack? I'd love to have flexibility to use the Champ 600 as a head so 4/8/16 Ohm outputs seems like a great idea. Is it possible to have all three readily available?

[tunghaichuan***]

I'd love to hear more about how OT's affect the sound. I have no experience & find it difficult to imagine what they would do.

Basically all an OT does is convert a high voltage, high impedance, low current signal into a low voltage, low impedance, high current signal that can drive a loud speaker. It is an interface between the high impedance tubes and the low impedance loud speaker. An OT is basically two coils of wire. An AC signal across one of the coils superimposes itself on the second. The primary connects to the tube(s) anode(s). The secondary connects to the speaker.

Generally a specific tube likes to "see" a specific primary impedance, or impedance range. It is a trade off between maximum power out (which most guitar amps go for) and lowest distortion (which most tube hifi goes for). 6V6s in single ended operation, like your Champ 600, work well from 5K to 7.5K.

Single Ended EL84 circuits like about 4K-5K. The original Valve Junior OT was 7.5K and it sounded terrible in that circuit. The new VJ OTs are 5.2K and sound *much* better.

Physical size is also a factor. The Hammond 125ESE, which is about 4 times the size of the stock VJ OT sounds much better than the stock OT. The highs and lows are much smoother. Which brings us to physical construction. The better the materials used in an OT, the better it sounds.

What exactly does a tap mean? Are these wires that one needs to solder onto a jack? I'd love to have flexibility to use the Champ 600 as a head so 4/8/16 Ohm outputs seems like a great idea. Is it possible to have all three readily available?

Taps can be either on the primary or secondary. The primary and secondary are merely long coils of insulated wire. A tap refers to a connection of another wire somewhere along its length. Usually a tap on the primary (tube side of the circuit) is an ultra linear tap, which is mostly used in hifi circuits, but has been used in a few guitar circuits, notably some early 70s Fenders and the Dr Z Route 66.

Taps on the secondary are for interfacing with 4, 8, & 16 ohm speaker loads.

Your Champ has one speaker out jack, no? I'm not sure if there is enough room to add two more jacks or not, you'll have to check. Another option is that you might be able to shoehorn an impedance selector switch into the amp so you can have a selectable impedance out, a la Marshall. My personal preference is to have three separate jacks as there is no switch to fail.

I really need to save up some cash and buy either the Champ 600, or the Gretsch G5222 which is the same amp with different cosmetics.

tung

[tot_Ou_tard]

Your Champ has one speaker out jack, no? I'm not sure if there is enough room to add two more jacks or not, you'll have to check. Another option is that you might be able to shoehorn an impedance selector switch into the amp so you can have a selectable impedance out, a la Marshall. My personal preference is to have three separate jacks as there is no switch to fail.

tung

It's fantastic to have you back tung!

Yes, it has one speaker out jack. Maybe I should wait until I have a cab to change the OT.

Does a beefier OT make the amp louder? I don't really want it to be louder. The volume works very well for me.

[tunghaichuan***]

It's fantastic to have you back tung!

Thanks, good to be back.

Yes, it has one speaker out jack. Maybe I should wait until I have a cab to change the OT.

If the OT you get is much taller than the stock OT, that may be a good plan. It looks like the speaker magnet is fairly close to the top of the OT.

Does a beefier OT make the amp louder? I don't really want it to be louder. The volume works very well for me.

Theoretically, no. The power tube and speaker's sensitivity rating determine how loud the amp is. Having said that, you may get more perceived loudness due to the extended highs and lows of the beefier OT. But again, the speaker can only reproduce sound in its bandwidth. You're not going to get thunderous lows out of a 6" speakers.

BTW, the speaker really is a limiting factor in bass response. I used to run a Silverface Champ into a 4 ohm 4X12" cab and had no problems getting massive amounts of bass out of that little 5W circuit.

I did a quick check on the net and found that the Eminence Alpha 6A is a 6", 8 ohm speaker. It has a sensitivity rating of 93 which is a lot less than the 97-100 of most speakers. It is also rated at 100 watts I wonder if it would fit in that cabinet?

tung

[tot_Ou_tard]

Theoretically, no. The power tube and speaker's sensitivity rating determine how loud the amp is. Having said that, you may get more perceived loudness due to the extended highs and lows of the beefier OT. But again, the speaker can only reproduce sound in its bandwidth. You're not going to get thunderous lows out of a 6" speakers.

BTW, the speaker really is a limiting factor in bass response. I used to run a Silverface Champ into a 4 ohm 4X12" cab and had no problems getting massive amounts of bass out of that little 5W circuit.

I did a quick check on the net and found that the Eminence Alpha 6A is a 6", 8 ohm speaker. It has a sensitivity rating of 93 which is a lot less than the 97-100 of most speakers. It is also rated at 100 watts I wonder if it would fit in that cabinet?

tung

If perceived loudness is only due to some extension of the frequency response, I can live with that for benefit. Yes, I know that a 6' speaker is the limiting factor. Someday, I'll get a cab.

I have a Weber 6" AlNiCo in there now which I am very happy with. I don't want it quieter, just not too much louder.

[tot_Ou_tard]

On another forum some players have discussed replacing the grill cloth on these.

They claim that the thick material mutes the sound.

Is this nonsense or could this be worth doing?

Here's a review:

http://guitargear.org/2008/03/03/rev...0-post-mortem/

[tunghaichuan***]

I don't know if this has been posted, but here goes:

http://300guitars.com/index.php/arti...-champion-600/

As far as the grill cloth goes, how thick is it? How close is the weave?

tung

[tot_Ou_tard]

I don't know if this has been posted, but here goes:

http://300guitars.com/index.php/arti...-champion-600/

As far as the grill cloth goes, how thick is it? How close is the weave?

tung

There's no weave, it's faux suede & seems rather thick.

[tunghaichuan***]

There's no weave, it's faux suede & seems rather thick.

Hmm....

How is the grill cloth attached? Would it be easy to remove? Most importantly, how does the amp sound through the grill cloth? I know Antique Electronic Supply sells acoustically transparent grill cloth, but the question is: would it be worth it?

tung

[tunghaichuan***]

Picked up my Champ 600 today.

After about 20 minutes of scraping, I still could not get the preamp tube shield off. I ended up removing the screws holding it down and removing both the collar and the shield. I had a spare collar and shield in my tube socket stash so I just replaced the one that came with the amp.

I replaced the crappy Chinese 6V6 with a NOS GE 6V6GTA and the preamp tub with a Sovtek 12AX7WXT. I was getting some residual noise, so I swapped back the stock Chinese tubes, but the noise was the same. Next I tried a JJ 6V6S, and it sounded the best of all.

The amp is excessively bright, even with the thick grill cloth covering the speaker. The tiny speaker sounds kind of tinny to me.

Just for kicks I hooked up my two 1x12" cabs loaded with Celestion speakers and the amp sounded much better.

There seems to be some power supply hum, does anyone else who has one of these have the same hum? It is not depended on volume of the amp, and doesn't go away when the guitar is turned down.

Edit: I checked a couple of transformers I have against the Champ 600, and it looks like the stock OT has 2 & 3/8" mounting centers. This is good news as there are couple that will bolt right up. The Champ 12 OT will bolt right up, but it is very expensive for what it is and only has an 8 ohm winding. A good replacement might be the Ver 1 & 2 Valve Junior OT. It has a 7.5k primary. The combo amps had 4 & 8 ohm secondaries and the heads had 4, 8, and 16 ohm secondaries. 7.5K was a bad match for the EL84 in the VJ, but it is better suited to a 6V6 anyway. My guess is that the OT was originally designed for a Champ circuit, but Epi put them in the VJ because they got a lot of them cheap. Even the new version 3 OT would work even though it has a 5K primary. But it does have the advantage of 4, 8, & 16 ohm secondaries. Finally, the Champ OT that is sold by Triode Electronics can be ordered with 2 & 3/8" mounting centers, has 4 and 8 ohm secondaries and costs less than $20. And it is made in America, Chicago to be exact.

Definitely a candidate for a gut and rebuild.

tung

[tot_Ou_tard]

Mine had some hum in the beginning, but it's either gone away, or I don't notice it any more.

[tunghaichuan***]

To those of you who have Champ 600 amps, would you do me a favor?

Turn on the amp and let it warm up. Listen to the speaker with the volume all the way down. Does the amp have any hum?

I took mine apart to change the tubes and now it seems noisier with more hum than it did. It could be my imagination though.

TIA,

tung

[Bilsdragon]

Has anyone tried a TS9 with this little puppy? I'm more an operator than a tech when it comes to amps and such, so I'm not sure if it's ok to run your pedals thru this thing or not. A sound clip would be great. :

[markb]

Have at it with pedals without fear I'd say. The only problem I could see would be boosting the bass too much and blowing the speaker but that's an issue with any amp if you run it flat out.

[tot_Ou_tard]

Several months ago I replaced the faux suede grill cloth with an oxblood one from Antique Electronics Supply. The Oxblood with yellow would have fit the aesthetics better, but I knew that I wouldn't be able to get the yellow lines neat & parallel.

I'm about to pull the trigger on an OT.

tung, do you still recommend the Heyboer VJ replacement. What do you think of Mercury Magnetics? Too pricey? Which one would work?

[tunghaichuan***]

I'm about to pull the trigger on an OT.

tung, do you still recommend the Heyboer VJ replacement. What do you think of Mercury Magnetics? Too pricey? Which one would work?

FWIW, having not tried either one:

The MM OT is going to be expensive, but by all accounts it is supposed to sound very good.

The Heyboer will sound good as well. If you're talking about the one that the Turretboards.com site sells, the 6.6K primary is a good match for the 6V6. It also has 4, 8, and 16 ohm taps which is nice.

One thing I've been meaning to try is to put a 7.5k Ver. 2 Valve Junior OT in my Champ 600 to see how that sounds. I would bet that it doesn't sound as good as the Heyboer or MM OTs

tung

[tot_Ou_tard]

I'm leaning toward the Heyboer, but for comparison's sake, which Mercury OT would work?

How do the various taps on the Heyboer work given that the speaker in the 600 is 4 Ohm?