A new amp build. Help!

[danmc]

Hey guys, I'm dan. I recently decided to get into building valve amps, as I've played with them in my setup for a few years, and have some prior electronics experience, and I thought it couldn't be to difficult..
Gosh I have some respect for you guys now!
Basicly, I wanted to build a High octane. Im not a new comer to the electronics game, and I've been looking at this for a while now, so I thought now would be a good time to go ahead.
So, I've built this high-octane, its sat, infront of me, right now. I have a problem. Or so I think.
Basicly, Power on, heaters come on, as you'd expect! What did greatly alarm me was, however, that the 12AX7's heaters started off *very* bright, well, for valves anyways, the light quickly died down to the usual orange valve glow. However, I flipped the standby switch, and the fuse blew. Instantly.
Now, I'm thinking that, the fuses I have are not slow blow. Is this likely the issue? I checked my not particularly neat wiring for 3 hours afterwards, but I'm confident that this is not at fault. (I'm probobaly wrong)
Now here comes the most interesting part, you may be thinking 'how on earth can you not know if they are slow blow, You bought them!' Well, I did. The thing that is interesting is, I'm in japan. I'm here for another 4 months aswell.
I think that just about says everything.
Oh yea, I'm 18 years old! As a result, I am down with the heavy metal scene, have long hair and listen to metallica alot (Ok, maybe not the last 2, Its a nice stereotype though). And hence me building a high octane, and not a P1!
I'll post some pictures when I get it done, aswell.

[NitroWoman]

Some brands of tubes flash on turn on. If they settle down quickly, I wouldn't worry about it. As far as the fuse, I use a 1A Slo blo in my HO. If your wiring is correct you should be OK. Standby to play with your lead dress, a HO can be a real beast to tame if you didn't get your wires laid out properly. I hope you added the Octal socket mod. My favourite output tube is a 6EZ5 although a 6V6 is really nice also. Good luck.

[mchauck]

It has been said many times here so I am only repeating the wise words of others. Pease check out the attached site and follow it carefully, no religiously. That should protect you and your amp while figuring out the problem.

http://www.paulamps.com/info.html#FirstPowerUp

BH

[s2]

A fuse blowing is indicative of some kind of short or near short. If it seems to be tied to the standby switch, check all the wiring around your B+ all the way through the power supply chain. Look for any areas of potential shorting. Also look for resistors that may not be the right value like 47 Ohms instead of 470K.

[danmc]

Wow thanks for the fast replys.
I'll follow that guide in future, and I'm going to buy slow blow fuses tomorrow.
As for shorts, I looked around alot with the trusty multimeter, but I'll have a look again before I do anything.
As for my lead dress.. Well.. Err.. I bought a 10 meter packet of cable. There is now just less than a meter.. And I only 'wasted' about half a meter.. This could be a noisy amp!

[mchauck]

Also, can you post some pictures? It is always helpful. Good luck and welcome to the site!!!!

BH

[SuperDeluxe]

Hey Dan, it's the first time I'm trying to give advices in this forum but I would go like this: Build yourself a current limiter, that's a device that keeps the fuses from blowing and keeps your amp "alive" though there's a fault somewhere in the amp. A current limiter can be easily built using a double 120V female outlet. You simply hook the wires in he outlet such, that the first outlet is in series with the second, in the first plug you put your amp and in the second plug, just plug a 100W bulb. Turn the amp on. The light will light up bright, but soon will dim, when the capacitors are fully loaded. Turn the standby switch on after a minute (letting the tubes warm up a bit), if the light bulb will light up bright, turn the amp to standby, and remove the power tubes, turn the amp on again, if the light goes out, one of your power tubes is shorted, if the light is still on bright, it's a bad rectifier, f***ed up filter caps, power tranny shorted or bias supply fault.
Hope you'll get the problem that way, if you tested the tubes good, state a comment and I will tell you the further steps.
See ya
SuperDeluxe

[Mooreamps]

Just what I was thinking. Build the current limiter as he described. If I had taken the time to do this, it would have saved me some time when I first brought up one of my 1.4 KV Beam Power Supplies.

-g

[danmc]

Well, got the fuses today, put one in, and it didn't blow!
Unfortunately, however the amp isn't working for 1 reason or another..
When either gain 1 or master volume is set past 11 oclock, Something from the amp itsself starts to make a high pitched squeal (ie, not coming through the speakers), of course they are connected, and I did check to see if they were shorting somewhere.
And I've never seen an EL84 before, but it looked like it was wayyyy to bright. This leads me to think I've messed up in the power amp section? But then why does the squeal also happen from Gain 1? hmmmmmmm
Could be a while before this is working, that is of course, if I haven't killed the EL84 (only a cheap sovtek, to be fair). Ugh.
Is there anyway to test if I've done the preamp right?
This photo is going to be of no debugging help to you at all, but you will laugh at the mess this amp is. :/

A few notes:
Power tranny is diffrent, no center tap, and such, so I'm using a full bridge recto, (its also a lower voltage too)
I kind of lost the will to wire up the pilot lamp.
Its messy
Its Really messy
for the cathode resistor for the EL84, they had no 220 ohm 5 watt resistors, so I just put a 200, and a 20 in series.

As I said, the new fuse doesn't blow, and my mains hasn't tripped, so it can't be that bad.. Can it?
Thanks for the help!

[kollantai]

your going to have to shorten as many wires as possible and get the layout more squared away.

[Francis_Vaughan]

high pitched squeal
Its messy
Its Really messy

That is pretty much a tautology. If it is as messy as that there isn't much chance it won't go unstable.

for the cathode resistor for the EL84, they had no 220 ohm 5 watt resistors, so I just put a 200, and a 20 in series.

There is actually little to no point in worrying about that. 200Ω will be fine.

You really need to clean the build up. The wire you have used is really over the top, you can't possibly need wire that heavy. It is clearly making life hard in getting a good layout.

Some of those solder joints joining components to the tags look suspect.
Actually these little tag strips are making life hard too. If I have ever used them I use them the other way around - solder the components through the holes in the ends of the tags, and any connecting wire through the mounting rivet. But they are far from ideal.


Don't use electrician's tape. It is really horrid stuff. It will go nasty and gooey and fall off. It is worse than nothing. Heat-shrink is your friend.

[danmc]

Ok, I've decided, after much hair tearing, to do the following:
Get rid of nasty blue wire and,
Replace with single core wire.
I'm hoping that the rewire will solve all my problems and world hunger and stuff.

I got the heavy wire, to be safe. Although from what I've read since then, it seems it was wayyy to over kill. With the exception of the power supply stuff.
Fortunatley, Nagoya has electric components shops.. Alot of them, and they are usually quite cheap. Anyways, thanks for everyones input! I'll photo and maybe do some sound clips when I finish it.

Oh yea, and I'll get the heat shrink too!

[Mooreamps]

Two comments.
One, don't need heavy wire. Only use heavy wire for tube filaments, the rest can be either 22 or 24 guage.
two, on your photo, lower left, next to the pilot lamp, looks like a solder bridge on the switch on the left, and no solder on the switch on the right.
-g

[Strat]

Yep, very hard to see what's going on in there!

I don't know what part of the world you're in but the wire gauge referred to here is AWG, American Wire Gauge. If you have any junkyards near you or know of anyone with dead/redundant computers the power supply to board and drives wire is ideal for hook-up, and above all free!

Try and us a colour scheme, twisted Red/black for heaters, Green for grids, Yellow for plates, Black for grounds etc. It will make it easier to identify where everything is going. If you can pick up some thin coax that might come in useful and it dosen't have to be super dooper, mil spec, teflon coated RG174, but that can sound good if you ever come to sell your amp

[danmc]

Well, I had a look at it.. You would not beleive what I'd done wrong.. (well, its not that bad, I guess)
the input and speaker jacks were wired up incorrectly... Ugh.
Now, it switches on, and there is sound! Nice sound! Only, nice as in, there is guitar signal coming through, but its not much, and it sounds really rubbish. Listening to other High octanes out there, it would seem something is wrong. Let me describe the sound a bit.
Ok, the guitar signal is getting through but:
There is very low amounts of gain
The tone controls do very little to shape the sound
When you turn gain 2 up, the sound becomes really tinny and harsh, and no bass at all.
And the EL84 still looks red-er than I would of expected! (Although, this could be normal, I don't really know.
Oh yes, and its really quiet.
I checked the voltages, and they seem to be a reasonable amount over the spec voltages (B+ is like 330 as opposed to 270), but I wouldn't of thought that would be it? is it possible the high B voltage is the cause of my problems?
Thanks for everyones help!