diytube.com

OK. A little more progress. I forget sometimes how much fun this is.


Don

OK, so I finished wiring the amp today. It worked first try! The right channel made 34 watts and the left channel made 32 watts. I guess I could try tweaking the negative feedback to balance this. I am very happy with this build. Tell Shannon it was the easiest so far and went together like a dream. And did I mention it worked first try? What fun it was to spend the day soldering and have such a good outcome.

Don

Awesome!!!

dhuebert wrote:I guess I could try tweaking the negative feedback to balance this.

You don't want to do it that way.... you'll end up with different damping factors and dynamics on each channel.

32 vs. 34 watts, you won't hear the difference. The minimum discernable level is 3dB and even 2dB by a "golden eared guru" - 3dB would mean one channel doing 17 watts and the other 34 watts.

Cheers!

That was my basic thinking as well. I was hoping Shannon would chime in and give some advice. I haven't tweaked any of the pots as yet so I don't even know how it's biased! It ran so well on startup and made such nice waveforms I didn't even think to do anything. Tomorrow I will put some square waves into it and set the bias etc, we'll see what it does.

Don

The ST70 in it's new home. For the moment it has JJ 6L6s in it but I will have to find some EL34s soon enough.


"Green back fly got your tail shakin'
sittin' on my slab of bacon
green back fly what you 'bin takin'
is mine, mine, mine, all mine."

Don

And my wife thinks my bookshelf speakers are big... :-(

Don --

The difference in power output between the two channels likely lies with the power output tubes themselves, or possibly the output transformers too, but that likely hood is more rare. Geek is absolutely right -- you'll never be able to tell the difference in use. Nice job!

Dave

Nice!
I just wish I HAD a garage instead of small table in the kitchen of a small apartment.
Can you really hear that red phone ring with the music cranked up?
Did you try mounting the speakers with the horns both inside and outside to see what gave better separation? Ot did it matter?

I didn't give the arrangement of the speakers much thought, in the garage it is less about HiFi and more about just having something to listen to. I built those speakers in 1981 as vocal monitors for a local garage band. They came back to me a few years ago and it took some time to figure out what I was going to do with the huge things. They aren't really music speakers at all but they do the job.

No I can't really hear the bat phone with the music turned up or the grinder or the compressor or etc, etc... Sometimes when I'm doing something on the bench grinder I can hear a funny ringing sound faintly, more often wondering WTF? than actually answering the phone.

Don

BTW this is what I'm doing in the garage these days:

A flat 4? Does it go on a Subaru? Looks too small.

DeathRex wrote:A flat 4? Does it go on a Subaru? Looks too small.

That's for a John Deer 42" rider.

That looks like a 36hp to me! COOL!

My mother has one of those. It does sound strange for a lawn mower, didn't know it had 4 cylinders. Seems like overkill. I have a non motorized Scotts mower. Could have got a cow, but I wouldn't want to go walking though at night.

On the ship we had, I do believe, an opposing 24 diesel generator. 12 on top and 12 on bottom. Looked like it could run the whole ship.

The prize goes to Terry Smith for a sharp eye. All the Volkswagen stuff in the garage should have been the tip-off. I bought 6 36 Hp motors last summer and found one that was worth rebuilding. It is just for fun as I don't have a car to put it into ...yet.

Build thread:

http://www.thesamba.com/vw/forum/viewto ... 93#4954393

Don

I'll bet finding 36hp parts is very challenging since EVERYTHING is different!

25 - 30 years ago I had quite a collection of VW's and parts, mostly junk! My favorites was a 63 Ghia- original paint, no rust, a very nice solid car until it got rear-ended by a 78 T-bird. Then I had a really nice 71 Super Beetle, and most recently a 2000 air cooled Mexican Bug.