YMI5150 Early '68 12xxx build journal

[vanhalen5150]

I wear gloves all the time as well.

[vh junkie]

You solder with gloves on?

I've worked with a lot of pros, and the only one I ever saw wear a glove was the guy who was splicing in my new 200w home service... of course he was standing on a ladder splicing live 240v mains... and he only wore a glove on one hand! Eeeheee!

Actually doesn't sound like a bad idea... what kind are you using?

[vanhalen5150]

Regular cheap work goves made from leather/swade. When I take the chasis out I wear 2. After I'm sure there is no current left I wear one on my left hand for everything. Im a righty.


I'm no pro but every one of them tells me a horror story about burnt fingers or intermitant cardiac arrest. I tell them what I do. Their eyes get wide.

[Strat78]

So I have a couple of days while the family is away, so I'm going to let amp run all night. What I've been doing so far to break it in is to get the low E string to produce a nice sustained feedback. Is this ok for the amp, I mean letting one note ring for 12 hours at a time?

[vanhalen5150]

So I have a couple of days while the family is away, so I'm going to let amp run all night. What I've been doing so far to break it in is to get the low E string to produce a nice sustained feedback. Is this ok for the amp, I mean letting one note ring for 12 hours at a time?

Not sure about 12 hours. 2-3 hours at a time. Remember with constant fluxing of the speakers the mags will get hot from your coils. Same as breaking in speakers with a variac. Just to be safe I wouldnt let it go that long. However, I did leave mine on overnight with the amp dimed and the guitar volume up slightly. It just wasnt feeding back a whole lot.
If your talking Hendrix feedback, I'd think I stay clear of that.

[Strat78]

So I have a couple of days while the family is away, so I'm going to let amp run all night. What I've been doing so far to break it in is to get the low E string to produce a nice sustained feedback. Is this ok for the amp, I mean letting one note ring for 12 hours at a time?

Not sure about 12 hours. 2-3 hours at a time. Remember with constant fluxing of the speakers the mags will get hot from your coils. Same as breaking in speakers with a variac. Just to be safe I wouldnt let it go that long. However, I did leave mine on overnight with the amp dimed and the guitar volume up slightly. It just wasnt feeding back a whole lot.
If your talking Hendrix feedback, I'd think I stay clear of that.

It's just humming away down there and I think I'm going to loose my mind! I'll let it go until midnight and then give it a break. It's not squealing craziness but just the low E vibrating (probably like the low E harmonic at this point). The power break is attenuating at about 50% but it still vibrates the gut when I'm in the room.

[vanhalen5150]

Cool.

[YMI5150?]

a lot's been going on since the stock build was complete. I've been working with VHJunkie and reading the plexi debate thread http://forum.metroamp.com/viewtopic.php?f=16&t=32292" onclick="window.open(this.href);return false;

and I've made a few changes based primarily on what was witnessed by Dave Friedman when he saw Ed's amp. To summarize a very long thread, it was illegedly stock with a few tweaks so here's what I did to add them:

V1b (bright channel) cathode resistor was dropped from 2.7k down to 820ohms. V2 .68 cap got a 250 uf (supposedly anything from 250-470 would suffice) electrolytic paralleled up and its supposed to use the 4 ohm tap for NFB with a 100k resistor but since i have the LarMar MV kit, I'm limited to 47k so I selected the 8 ohm tap.

The drop from 2.7 to 820 boosted mids to CVH tone bigtime. great change. it still wasn't quite there. too much flub, the closest I could get was dropping the volume to 8 and bass to 2. remember, this is room sound, not mic'd. big difference.
Junkie suggested I stop until I got a .0022 coupler. my kit and most others came with a .022. the smaller cap restricts bass that can be added back later. I added that last night, bumped the 250 electrolytic to 330 to get some bass back (lost some gain but had some to give), and swapped the .022 post PI couplers for .047s per Junkie to get some more bass back. Initial evaluation - it rocks!! much crisper gain on 10, no flub, tight bass. love it. time to play it for a while. its close and sounds great in the room.

[vh junkie]

Nice!