Homemade 5W Tube Amp

[Steve080]

Hi all,
Just thought I would post a picture of my latest home built Amp. It is 5W SE class A with 12ax7 and EL84. Quite loud for 5W and breaks up really nicely.

http://http://savefile.com/files/1931631 (http://savefile.com/files/1931631)

[AustinHohiemer]

Link doesn't work, but it sounds awesome. How did you build it? Did you buy a kit or build it all from scratch?

[Steve080]

There fixed the link, not sure how to link to the picture directly so you need to download.

I built the amp from scratch, transformers,valves I got of ebay, the case was from Maplin, the components I got from various shops.

The design is based on the Gibson GA-5 which the Epi Valve junior is alos based on.

So it is effectively a Valvle junior clone but with much higher quality parts.

I am actually planning on running this into the epiphone extension cab.

[martinedwards]

that looks sweet.

I've contemplated the idea of this sort of thing for a while now......

any idea on the cost?

is it a LOT less than an Epi VJ?

or should I just bite the bullet and get a VJ?

[Steve080]

Well you can build a decent clone for around £150. Epi's have gone up in price a lot recently, so around the same, but this way you have the pleasure of making it yourself and knowing that you have done it well.

[chongo]

that looks sweet.

I've contemplated the idea of this sort of thing for a while now......

any idea on the cost?

is it a LOT less than an Epi VJ?

or should I just bite the bullet and get a VJ?

I've got two Valve Jrs -- one's a completely stock model that I picked up for $99 from Musician's Fiend just before the price went up to $130. The other is non-stock, modded using the Mercury Magnetics kit, which not only replaces two transformers and adds a choke, but also replaces a few small bits and adds a socket for a 6V6, so that you can use the already-there EL84 *or* the 6V6...or both at once. The kit alone, however, has a price tag of $299 (plus shipping) and most techs want another $100-150 to install it. When completed, there's no indication on the exterior that you've done anything different (unless you put their silly badge on, which of course is on mine), but there's a definite sound difference. I've not been able to describe it -- I usually have to sit someone down with both, and then they get it.

If I'd had to pay for it, I probably wouldn't have taken the chance on it (what the hell, it takes a $99 amp head and turns it into a $500 head and it's not even gold plated?). But my point, I guess, is that the EVJr is a good amp in and of itself, and that you can modify it to the point where it's pretty much amazing simply by swapping out components here and there. I've probably mentioned this before, but my favorite speaker cab for this thing is an old 4x10 open back cab with Jensens that's been done in tweed tolex and oxblood grill cloth. It's way more speaker than it needs (a single good 10" in a cab will do fine), but it's *very* pretty this way.

[Steve080]

You have hit the nail on the head Chogo, the Epi VJ cct is a tried and tested circuit and sounds so sweet with the right components!

I have fitted a hammond 125CSE output transformer, a 100va 0-260-0 power tx with a 6.3V tap for the heaters at 4.5A.

The heaters are rectified to 6V ish DC with 12,000uF of caps to smooth it.

I have used 100uf on the 320V audio transformer supply, over the 22uF that is fitted, this really improves the bass response.

I have also added a lot of spike protection and surge protection that is non exsistant on the standard amp.

Also added high frequency decoupling to eliminate those annoying interferances that you get when your mobile rings etc.

[Steve080]

Here's the image to save downloading it:

http://i375.photobucket.com/albums/oo191/steve080_photo/ABCD0001.jpg


Now I have had a bit of time with this amp I can only say 'Upgrade your Epi VJ' you won't beleive your ears. This thing is an absolute beast. The notes are so clear.

I thought the bass response was a little lacking on my Epi combo little buzzy, but put this down to the 8in speaker, but it;s not the speaker, with my modified version the bass is awesome, as well as the highs.

Looking forward to opening my 12in epi cab now,girlfreinds got me one for christmas.

[Keith]

Nice looking amp there Steve;) I would love to hear what this one sounds like:).

I was thinking about building one myself a 30W. I've never made one before, but I have repaired them. What's the expertise level needed to build a clone?

[Steve080]

Well Keith,
I'm an electronics engineer by trade, but I mainly do digital and power suppply electronics, when i first built this amp I was thinking wow 'this is gonna be so cool' but when I powered it up it sounded like I had a swarm of flies in my speaker. Anyway I had a chat with one of the senior engineers who I know, he suggested a few improvements that I could make and now I have the amp which will do me just fine :-)

Level of skill to build is not high, if you can use a soldering iron well, and can drill, etc, work a peice of aluminuim you can do it.

But the sound quality that you receice is so dependent on how you ground the circuit, thats what I learned by building this amp.

But I would say go for it, you may need to alter it, but you will learn a lot from doing that and you will end up with the only amp in the world that has the tone that yours does, that was my incentive.

[Keith]

Thanks for the info Steve. Would you be able to recommend a kit that would be easy to build?. I might just go for a 5-8-10 watter just to get my feet wet.
Bending aluminum.. Sheet metal for body repair is about the only experience I have. drilling and motherboard work I can do.

Thanks in advance:)

[Steve080]

I would recommend the following kit:

This kit is very good at a very resonable price I think, I know how much it cost to build mine from scratch so I know the cost of the components. This fellow can't be making a huge amount of profit on these. I have ordered from this site before, very prompt delivery, very well packed.

http://www.ampmaker.com/ak01x.asp