Quote from: J M Fahey on March 01, 2010, 03:22:29 AM
Hi E.
Indeed your suggestion is quite ON topic.
I didn't tell Zappacat *not* to use them, but to mount them *inside* an unreachable chassis or otherwise make it impossible for curious hands to get in trouble.

Thanks, I got that part.  If I use a kettle socket, which wires go to which terminals on the power supply?  Thanks

How do I wire this thing to a grounded (USA 3 pin) socket?  I'm assuming the far left terminals labeled L and N represent LIVE and Neutral.  What about the ground pin coming from the wall?  Do I connect it to the pin with the ground symbol?  I'm assuming if I connect this correclty that I should get approximately +24V and -24V AC coming out of -V and +V.  Is that correct?

Could I power a couple of LM3886 chips with this power supply?  Is this power supply adequately suited for this application?  I'm really low on cash right now and I stumbled onto this for $10 new.  Thanks in advance.

Mean Well S-60-24 PDF link below
http://www.meanwell.com/search/s-60/default.htm

I can't believe I didn't consider that.  After I read your post I started looking at some of the amps I have around the house and noticed they were ALL mounted behind the baffle board.  For some reason I had it in my mind they should be mounted on the front side.  Guess I would have known if I had taken the speaker out of the box and seen the mounting gaskets on the front side of the speaker.  Thanks for pointing out the obvious to me.  I guess I get the Beavis and Butthead award for the month.  Possibly the year.

Anyone know of a protective grille mesh I can pick up at home depot or lowes that's suitable for this application?

I've got both of these speaker cabinets on the drawing board right now :

AX84 1 x 12" Speaker Enclosure

AS112A Plans

I have one of them (AS112A) about half way through assembly and I realized there won't be any space between the front edge of the speaker(once installed) and the front of the speaker cabinet itself.  This leaves me with no room for putting a protective screen or something in front of the speaker unless the protective screen/shield extends beyond the front of the speaker.  Am I missing something here?

What do you guys use for protective speaker mesh / screen ?

I realize at this point that a simple solution to this is to increase the depth of the cabinet box so I can inset the speaker mounting position more but I've already cut the wood and from my understanding these cabinets are designed so that the internal cabinet volume/area is critical to the way they sound.

Thanks in advance.

The AS112A speaker design PDF calls for using "2NR M5 tee nut" to secure the carrying handle to the top of the speaker cabinet. I'm here in the US and everything is in "standard" measurements at the hardware stores for this type of fastener. Can someone please tell me what 2NR and M5 mean in this specification? If those numbers pertain to metric sizes what should I be looking for in a standard size equivalent?

reference link : http://www.award-session.com/award-session_projects.html

Thanks very much in advance

Phil, I can't tell you how much I've appreciated your help over the last year or 2 since I've been a member here.  Your expert advice has really helped me in trying to learn about electronics and given me the enthusiasm to keep plugging away at things when I was about to give up.

I need some help with this combo amplifier.  I purchased it recently knowing it was damaged in some way.  The fuse was blown so I replaced it with proper one.  First power up blew the fuse again instantly and the unit started smoking inside.  So far I've removed the amplifier chassis assembly(all the electronics) from the wooden speaker enclosure and the attached pictures are what I'm looking at.  What's the best way to test the toroidal transformer without damaging it?  Is this where I should start?

I don't see any visual clues that would indicate what was burning.  The only odd thing was something that looked like ash next to the led assembly on the front of the chassis.  Should I risk throwing in another fuse with the chassis out of the cabinet so I can possibly see something burning? 

Any help greatly appreciated.

***Linked content removed due to malware***

Sounds fantastic.

I recently purchased an oscilloscope(PROTEK 6502 20Mhz-2 channel trace Oscilloscope) that didn't have any probes.  By mistake I bought a probe (Avex 10x oscilloscope probe 100Mhz) that has a higher frequency rating.  Can I use the probe with this scope?  What are the implications of using these two together or will they even work at all?

Thanks!

Thank you very much.  I keep seeing this thing called chip points on the forum while browsing through posts.  If I could award you one I would.  I just don't know how.  Can someone please tell me how to award chip points on here?  I owe a huge debt of gratitude to so many people on here.  Can someone please tell me what's up with this?

The chipamp build list I got from bryan calls for MUR860GOS-ND.  Digikey is out of stock on these until 12-23-09.  Mouser is out of stock as well.  Can I substitute these MUR860 8A 8 Amp 600V Power Rectifier Diodes that I found on ebay without sacrificing performance/quality of the final product?  Any advice greatly appreciated.

Quote from: J M Fahey on November 04, 2009, 11:57:26 AM
Hi Zappacat.
Most general purpose multimeters aren't sensitive enough to measure such low voltages, unless they have a 200 mV AC full scale range.
If you have one of the latter, hook one to a plug, plug it into your guitar with all controls "open" and play.
You'll measure around 200mV on full chords, and 10 to 50 mV picking single strings.
Measurements vary wildly with different pickups, strings, mics, whether you use a pick or not, and even how tired, bored, or excited you are.
If not possible, design considering your guitar a 50 to 100 mV generator (with occasional 500/800 mV bursts) and you won't be far off.
I've drawn  some schematics for you, about a step-by-step build, from the simplest LM386 project, to an LM3886 50W amplifier, driven by said LM386 used as a preamp/distortion. A 2 Knob 2 switch amp usable in jams and gigs.
After you build and test it, it's relatively simple to embellish it with different preamps, tone controls, effects, whatever , but you start with something always usable.
I'll scan and post it in the other post.
Good luck.
Juan Manuel Fahey

Thanks to both you and Enzo for your help.  I can't tell you both how much I appreciate you guys answering my "beavis and butthead" questions.  I was really looking for the voltage range to be expected(from the guitar signal out) at this point of the design and understanding phase.  From that point on I want to work out(mathematically) what the signal level would be as it moves upwards through the gain stages of the preamp -> power amp -> speakers.  Since I don't have a lot of advanced electronic analysis hardware I really needed to know the expected voltage envelope that is coming from a typical guitar output to reference as a starting point for later calculations. Based on what you've said I'll expect it to be anywhere from 50mv to 800mv.  I'm looking forward to see those schematics.  I'll post my build when I'm done in a coherent format so it might help someone else in the future.

Just one more thing, if I had an oscilloscope and everything I needed to plug a 1/4 inch jack into my guitar, what measurements would I actually get out of it?  I realize there is a waveform and voltage but what else is there?  I think I'm missing something really fundamental here and I'm lost.  What is the waveform a product of?

Thanks again guys!

How do I measure the output signal strength of my guitar?  Can I do this with a voltmeter?  I'm trying to start my first SS guitar amp and I'm trying to trace the signal levels from the guitar to the final output stage.  This may sound like a stupid question for someone building their won amp but I'm stuck at square one.  Any help greatly appreciated.

Are you named after Fangio?

Quote from: mensur on October 09, 2009, 06:59:04 PM
I made that amp a few years ago and it's awesome.
Here are my samples:
http://www.esnips.com/doc/d6a08723-1fef-4ab9-afd4-f8520f273388/Randall-RG100ES-Boost-1
http://www.esnips.com/doc/489be47f-e102-49d0-aac5-b09ee8a4870b/Randall-RG100ES-Boost-2---Scooped-Mids
http://www.esnips.com/doc/619f7c75-6446-4b4c-85d6-6bd8258b2137/Randall-RG100ES-Boost-1(Solo)

1.Yes the red channel is the distortion channel
2.Caps are in micro farads (10uF on the source of Q6)
3.Yes they are 4V Zener diodes,(1N914 are clipping diodes,or boost in that amp, but they attenuate the signal a lot).

The first and last clips sound amazing.  What were you using for power in that amp?  Any schematics or layout?  Very nice work.  Thanks for sharing it with us.