Help needed IDing a Champ-like head

[jimmywaleseswhale]

Hi,

Somebody is selling a prebuilt tube head for $150. I was always curious but never had the nerve to build a full kit from scratch. Would be a nice way to dip into this hobby.

Apparently is based on a Champ but not sure which one. It has three pots (tone/volume/gain?) so looks like a mod. Only runs on one 12ax and one 6v6, so presumably has a solid state rectifier?

Any info on IDing the kit this is based on would be appreciated. Likely to be EUR/UK. I'm not even sure what's the wattage. Any thoughts how Champ-like it could sound it's likely to sound would be appreciated.

Is $150 (£100) good for it? Appreciate the help!

[TUBEDUDE]

Power xfmr alone looks worth it. If you don't like it, it looks like an easy mod queen.

[maxkracht]

What tubedude said. At the very least it is good for parts. My once over from the picture: looks like a lot of extra wire that could be removed, I don’t see a heater center tap/humdinger which could be easily added to lower noise. Safety ground is connected to the board instead of the chassis which is potentially hazardous, along with the power cord strain relief that’s a bit iffy. Otherwise, looks like a good deal and a nice place to start tinkering. Not enough info to give a good assessment on what it’s based on, but you could probably ask the seller.

[ChopSauce]

Not a kit. The transformers might look good but what about their specs? I'd measure the voltages to be sure, but still you don't know about the ratio of the output.

I recently rebuild entirely one sort of amp like that recently. The outcome came out underpowered. Now I'm on for (wasting my time) debuging (after havins spent too much time dismantling it properly) it and I'll certainly have to change the output transformer.

My experience is just my own, but I won't encourage you to do that. Starting from a kit seems way better, from my point of view. At least to learn how to build something properly.

Tubedude it certainly more experienced than me and he might be able to deal with that amp brilliantly, but I'm not...

[jimmywaleseswhale]

Thanks all!

The seller doesn't bought it off the guy who built it ages ago. Apparently was inspected for safety by some amp tech who also replaced a transistor (rectifier?). Don't think the seller has any additional details regarding the design.

> Safety ground is connected to the board instead of the chassis which is potentially hazardous, along with the power cord strain relief that’s a bit iffy

That doesn't sound good at all. Sorry for an idiot question but this should be easy to fix, right? Could you point at the the safety ground wire

[ChopSauce]

With enough time and the willing to do so, you should be able to fix anything, really. If you do want to buy it, buy it. I'd just ask:

- what's your ambition?

In my book, having built a clean replica of some valuable amp as a Champ is much more rewarding in the long term.

[jimmywaleseswhale]

I'm getting back into playing an electric guitar after a decade of absence. I have a Vox MV50 Boutique and 12' cab. As all newcomers, I have an urge to try out new stuff. Getting something that sounds 90% like a Champ would be great – amazing tone, not too loud.

I was never that involved with electronics DIY but generally quite a technical person. Getting a cheap amp that already works and eventually improving it sounds tempting. With a new kit, I think the price might stop me for now. Appreciate it's a really fun hobby/job!

[ChopSauce]

So, that really works and looks like something you're willing to keep as is?

With a kit, can neglect hidden costs in a first approximation.

I do wish you the best with this amp, but my friend is somewhat sorry with his own, and he was enthusiastic with the way it looked since the beginning.

Your seller can't even give you any warranty about anything.

In your situation, I'd search a small overlooked production amp to start modifying, little by little. Low to no hidden costs, fair resell value. It might even cost less than this amp you shown.

[jimmywaleseswhale]

I'd like to get something that's solid enough to start off with. Not to disappoint everyone in the thread but I decided not to get the DIY one – maxkracht's note that it had safety issues were really concerning, even if somewhat easily fixable.

I do like the idea of a production amp/head with some ambition to mod it later. Seems like Laney Cub 8 (think it's marketed as Monoprice in the US) often comes up as a cheap and mass produced Champ-like amp? Any other suggestions?

[maxkracht]

I could be wrong about that ground, hard to tell anything definitive from the picture. The safety ground is the green and yellow wire on the mains power cord. It should be bolted directly to metal on the chassis so if there were an electrical fault, voltage goes to earth instead of your guitar strings, you, then earth. I don't think starting from someone else's kit/project is necessarily a bad idea if you are trying to learn about guitar amps, especially if it mostly works from the start. Inexpensive modern amps are likely much harder to mod for a beginner. I haven't looked at any monoprice amps, but I'm guessing everything would be mounted directly to a PCB which was built to a cost. This means desoldering parts from the board poses a fair risk of damaging it if you aren't careful/experienced/have good tools. The diy amp pictured could be modded and remodded dozens of times without damaging the board. I'm not trying to knock the monoprice thing, it likely sounds just fine, but I wouldn't want to learn electronics on something like that.

[Phil_S]

Do you want a low power tube amp at a low price point? Or do you want a project amp because you think you might be interested in the electronics because you have an inner tinkering itch that needs to be scratched? Or is it both, in which case you should scratch the itch?

If all you want is a low power tube amp at a low price point, you might look at this. I've seen people discuss it on youtube and it seems to get some favorable discussion.
https://www.amazon.com/Monoprice-611705 ... 467&sr=8-2
At $141 including shipping, it blows your $150 find out of the water. It's plug and play. If you want a project, that's different.

This head is a mixed bag. Someone with moderate experience probably wouldn't find it too challenging to fix it up if they wanted to put the time into it. For someone without experience, the fix up will be a longer journey. There are things to learn. Some of that is simple technique, like how to go about shortening a lot of that excess wire and making proper workman-like solder joints. Some of it is knowing what to leave along and what to fix. As a novice, you won't easily "see" what could and should be done. If you are up for the journey and are willing to put in the time and effort, it might be a good project for you.

As for the price, I'd say that depends on the transformers. I can't see the labels. Can you post what they say or clear pictures of the labels? That power transformer looks rather large for a ~5W amp, but size isn't everything. My gut reaction was same as tubedude, worth it for the transformers alone, but then I started to back away from that. It would be better to have some facts. Just because it works doesn't make it any sort of bargain at $150.

IMO, it is not a big deal to use a solid state rectifier in place of a tube rectifier. I wouldn't be concerned at all about that. Generally, the solid state rectification is just fine. (Let's avoid the rabbit hole discussion about sag, which I submit is a real thing, but beyond this thread.)

Another note regarding price. If you want a project amp, I used to find this sort of thing on eBay for $50 and under but prices have gone up. You decide at what price point there is no real guilt about digging into it or making an error. At $150, I'd start to feel an obligation to myself to be more cautious.

[martin manning]

IMO, it is not a big deal to use a solid state rectifier in place of a tube rectifier. I wouldn't be concerned at all about that. Generally, the solid state rectification is just fine. (Let's avoid the rabbit hole discussion about sag, which I submit is a real thing, but beyond this thread.)

Especially not a big deal for a Class A amp.

[echuta13]

Looks very similar to a 5f2a Princeton circuit.

[jimmywaleseswhale]

Do you want a low power tube amp at a low price point? Or do you want a project amp because you think you might be interested in the electronics because you have an inner tinkering itch that needs to be scratched? Or is it both, in which case you should scratch the itch?

This is an interesting way to look at this. I always thought of DIY amp making as a magical skill to create high-value equipment out of regular mundane components. Say 5F1 doesn't look like a lot of parts but has a very pleasing tone and semi-legendary status. Admittedly, component sets are still good $300-500 and do require some assembly skills. I was excited to buy that DIY amp because seemed like a good shortcut towards 'Champ-like' tone with an ability to make further improvements later on.

Between 'sounds like a Champ', 'is cheap', and 'is well modifiable' (choose 2), I'd pick cheap and Champ. I thought I could get all 3 with that DIY amp but sounds like it might not be a bargain (likely safety issue, DIY job so-so, hard to predict what it sounds like). I know that if getting just two of these would be a bargain too, there's a reason Fender is still making pricey re-releases I might look for a 'cheapest head/amp that sounds like a Champ' and hopefully get to scratch my DIY itch with another amp project

[martin manning]

The cost to build a reproduction Champ is amazing considering it was originally a cheap practice amp. I believe to get the whole package you need the cabinet and small speaker. Mojo's complete kit is selling for $575.