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**StukaJU87** · 01-17-2006, 10:55 AM

Re: DIY Soldano type preamp

I can't make heads or tails of it but it sure looks good to me. [img]/images/graemlins/laugh.gif[/img]

**jgcable** · 01-17-2006, 10:58 AM

Re: DIY Soldano type preamp

Is that modeled after a SP77? You have SLO100 printed on it. Is it the preamp circuit from an SLO?
It should have tons of gain if it is. It looks good. Anyway to post clips of how it sounds?

**Infernal Death** · 01-17-2006, 01:16 PM

Re: DIY Soldano type preamp

Now as far as i get it it's not modeled after the SP77. I don't have the schematics for the SLO100 nor the SP77. But the guy who did all the designing work stated that it's modeled after the SLO100 preamp section so that's why i wrote it on the frontpanel.
Well yes it does have quite some gain but i guess the voicing isn't really the one i want to use as my rhythm sound. However i should state that right now i just testplayed it over my small POS Peavey Rage practice amp so that could be a reason that it doesn't sound as good as it could [img]/images/graemlins/laugh.gif[/img]
I just need to finish this amp and then it's off to the cellar where my rectifier is sitting so i can plug it into the power amp of the rectifier and make a real test.
I try to make some samples while at it, i can't promise anything though.

And thanks for the nice words.

Flo

**mjtripper** · 01-17-2006, 01:25 PM

Re: DIY Soldano type preamp

Looks good!! Can't wait to hear the sound clips. I've been thinking of trying to build a small amp just as a 'see if I could do it' project. How many hours do you have into it? The design part is way above me, can you point me to where you got your plans? I've been checking out some kits online, which might be a better starting place for me.

**Cleveland Metal** · 01-17-2006, 02:39 PM

Re: DIY Soldano type preamp

Wow! That is pretty damn cool man. It looks very nicely done, and neat/cleanly assembled. Great work man. I'd love to hear a clip someday.

And maybe some info on how to get this schematic etc if this is available. Did you get a instructions and buy all the parts yourself?

**khabibissell** · 01-17-2006, 03:19 PM

Re: DIY Soldano type preamp

Here's a dumb question for ya:

Does a preamp like the one you are building above have the same shock hazards (meaning it can kill you) as a full tube amp would? (stored voltages, etc...)

**Cleveland Metal** · 01-17-2006, 03:27 PM

Re: DIY Soldano type preamp

Preamps are aren't as dangerous. But, typically, the 110 that is in parts of the preamp, going from one hand to the other hand routed cross your chest will kill you quite nicely.

Particularly, it's the power tube Transformer in the power section that builds 350-700 volts for the power tubes, and the caps that also store that energy after the amp is off, that is very deadly.

**Infernal Death** · 01-17-2006, 03:47 PM

Re: DIY Soldano type preamp

Well the power transformer used in my preamp is able to deliever 500V. However i only used one winding with 250V for the tubes (that's why there are quite some unused cables near the transformer). The highest voltage is right after the rectifier diodes where you have around 340V. And that isn't very healthy to touch.
But yes Cleveland Metal is right, the voltages in power amps are much more dangerous. However if you don't have experience and feel safe working with high voltages i wouldn't start with such a project.
Like Cleveland Metal also stated it's also dangerous because the caps hold the voltage for quite some time after you turned the preamp off. That's why i always wait 10 minutes minimum after switching off before i place my hands inside the unit.

Cleveland: You can get the info here:
http://www.andyszeugs.de/

Yes it's in german but the links to pics, schematics and other infos should be self-explanable. I've build the PR-2.
I pretty much got all the infos out of these files. I just wrote 2 emails to the guy who did all this stuff because of 2 questions. Since he has a parts list for german suppliers, sourcing the parts wasn't that hard.

**charvelguy** · 01-17-2006, 04:30 PM

Re: DIY Soldano type preamp

Like he said, even the voltages stored inside those caps could kill you. I once picked up a broken disposable camera that was lying outside. I accidently came in contact with an exposed capacitor on the board that held the built up charge for the flash. Needless to say, I was quite surpised at the jolt this thing gave me ....it was just a small capacitor.

**khabibissell** · 01-17-2006, 06:10 PM

Re: DIY Soldano type preamp

Obviously not a good place to start building projects...

Awesome job though, looking forward to the clips!

**Cleveland Metal** · 01-17-2006, 07:54 PM

Re: DIY Soldano type preamp

Wow, 340v? they are using some serious cool voltage in that preamp. That is the way to get the tubes where they need to be! I see a lot of preamps that use so little voltage at the 12ax7 that it is silly. I think my voodu used like 12 volts wall wart to power it, haha, and the Marshall JMP-1 uses very low voltage too.

I guess you have 220v coming out of the wall socket there too right?

I never bothered to measure it, but I got the crap knocked outta my with my CAE3+se... I have a mod switch "sorta" laying on the cicuit board and musta touched something umm good when i flicked it one day. I was barefoot and on cement floor. woohoo! Big Ouch! Lucky it just hurt... Stupidity can kill, and I was pretty stupid.

It doesn't take much to stop your heart kids.

Also... Waiting ten minutes for a cap to discharge won't do it man. Ya gotta do it yourself with a test lead to ground as they will hold voltage for weeks and still bite hard.

As for how much voltage a cap can build up with the appropriate surrounding circuit... Figure this, they make stun guns that will flat out knock you on your ass and they are powered by like 9v batteries!!!

**Twisteramps** · 01-17-2006, 08:40 PM

Re: DIY Soldano type preamp

Nice job man! I'd love to find a link to the boards... building something like that with turret board would be a nightmare. With the boards you mainly just have to worry about wiring the controls and transformers.

Regarding voltages - you can still get killed with a preamp! The upper limits for a 12ax7 is around 300 volts, and that is plenty to put you in the ground. Be cautious with this stuff... most tube preamps are going to have 150 or so to 300 volts. The ones running a lot lower don't sound as good imho, without a lot of solid state stuff running with it - they run a few volts through the tube more to 'warm it up' than just for the raw tone of higher voltage.

My opinion anyways. Again, nice job, excellent job with the chassis too, it's a real PITA to drill all those holes straight!

Pete

**RobRR** · 01-17-2006, 10:06 PM

Re: DIY Soldano type preamp

Man that looks great! Im especially impressed by the circuit board... building them all day, I can appreciate it! [img]/images/graemlins/grin.gif[/img]

Speaking of getting shocked... try shutting a car off by pulling the distrubutor to coil wire... ouch. Buddy of mine incorrectly wired in his MSD 6AL box, and the car wouldnt shut off. This was also right after a cam/intake/carb swap. The mix was off and the headers were glowing like a SOB and we needed it off. In the 1.5 seconds I was in contact with that wire I estimate I got shocked 10-12 times @ around 50,000 volts thorough the chest... forgot to let go of the fender first. Yowza! While getting shocked I ended up tossing the wire about 50ft down the road taking about an hour to find it. [img]/images/graemlins/laugh.gif[/img]

**Mordor** · 01-18-2006, 03:10 AM

Re: DIY Soldano type preamp

Great job Flo!It looks really nice! I'd like to hear some clip too!

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