First amp completed

[Ian444]

Here is my first scratch built guitar amp, very simple. 35 clean watts. Breaks up real nice as the 12AU7 cathodyne tries to drive some grid current into the PP EL34 outputs. I built the cab too, pine ply with Marshall tolex. Magnetic Components OPT. No other fancy parts. 3 piece chassis held together with stainless screws. Point to point inside and not real nice to look at sorry, despite a reasonable amount of planning, oh well, next time I might do better with some turret board. gut shot Its just great what new tricks a 50 year old can learn from the internet 25 years ago, if someone could have taught me how to build a tube guitar amp, I would have given a lot for that back then, it was an opportunity that simply did not exist at that time. Here is the schem.

[tubeswell]

I know how you feel.

[Drumslinger]

Nice going Ian. Great job!

[M Fowler]

Ian, nice amp looks great hope your enjoy it.

Acoustic amp is the input working well or is higher impedence needed?

Mark

[surfsup]

Ian, nice. Very nice. Your pic was confusing the heck outta me at first because you can only see one el34 even though there are two in teh schemo. I finally noticed the second tube's "top" hanging down from a socket you can't see on the guts shot that was cut off by my laptop screen just to the point where I didn't see it (until I saw the second cement resistor hanging off the strip and scrolled down).

Anyway, I love the amp. Would appreciate a gut shot from the other side if you are inclined.

[xtian]

"Not real nice to look at..." I disagree. Looks a lot nicer than most vintage PTP. Really pretty, in fact. More photos, please!

[Structo]

Looks great!
Where did you find the transformer covers?

[C Moore]

I would like to hear somebody (Tommy Emmanuel perhaps) plug an acoustic guitar into this head.
Do you use "PA" type speakers with this or just regular "guitar" speakers.
Thank You........Well Done

[Ian444]

Acoustic amp is the input working well or is higher impedence needed?

As far as I know most acoustics have an in-built preamp so input impedance is not an issue, but I'm not an expert on this area. This was the intended scenario anyway

Would appreciate a gut shot from the other side if you are inclined.

Sorry about the poor focus. inside2 inside3 early build pic with different OPT

Where did you find the transformer covers?

They came with a Chinese medium-fi amp I used for parts. The Chinese do excellent durable powder coating with the wrinkle finish, I love it. You near need a chisel and hammer to break the surface. I used part of the power supply PCB for the bias, their layout skills leave something to be desired in this particular case

I would like to hear somebody (Tommy Emmanuel perhaps) plug an acoustic guitar into this head.
Do you use "PA" type speakers with this or just regular "guitar" speakers.

For acoustic one would probably need some sort of full range (PA) speaker. Truth is I don't have an acoustic so I use a regular guitar speaker cabinet with elec guitar. The amp is good to 20kHz minus a dB or so.

It is surprising how well tonally balanced an amp without tone controls can be, but its probably only going to be good for the guitar you set it up with, and if I took it out of my fairly acoustically dead loungeroom and onto a bright stage, well, that might be another story, who knows.

I have experimented a fair bit with LTP vs cathodyne PI's, and the DC-coupled cathodyne really sounds sweet to me. If the PI is heavily overdriven the LTP retains its composure better on the scope, but other than that, for my old ears, the cathodyne is my choice. The only thing I can attribute this to is perhaps that the DC-coupled cathodyne is always preceded by a standard gain stage which the LTP doesn't quite have, and it uses 2 less caps, but that could be immaterial. Merlin (valvewizard) has some great info on both of these PI's.

[daydreamer]

Beautiful amp, Ian. Very inspirational. I like the flip cover power switch as well. Make me think I should do a pre-flight safety check...

andy