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Messages - syndromet

#46
Second the rewiring. Had a simular problem myself, my guitar was buzzing if I didn't touch the strings. Reflowing the solder joints helped.


BTW, I voted ..   ;)
#47
You could probably just put a tone stack in there, but I don't think it will sound that good.
First of all, you should build a preamp. The guitar signal alone is not powerful enough to push the poweramp alone, and a tone stack takes away even more of the signal. You should also use the preamp to match the guitar signals impedance to the power amps'. If you're going to just wire up a tonestack at the input, I would at least add an input and an output buffer to it,(wich again make it as complicated as the simplest preamps). You could really just add a ruby with a tone controll at the input, and run it of the same power supply as the 2003.

Thats my advice. Try the poweramp with just a simple tonestack, and then with one of your rubys, and you'll see what I mean.
#48
http://www.angelfire.com/music/harmonica/honeytone.html

Don't know if you'll find anything usefull in there, though. If it was my amp, I'd gut it and replace the internals with a noicy cricket or little gem...
#49
Schematics and Layouts / Re: 60W Power amplifier
July 06, 2007, 01:51:13 AM
Wow! :o
Amazing.....
#50
Don't really know if it fits in here, but the way runoffgroove uses jfets insted of triodes is worth mentioning. A few of those preamps sound pretty good on higher voltages.
#51
Looks great. Good to hear you got rid of the hum
#52
Amplifier Discussion / Re: Using car HiFi amps
June 20, 2007, 03:13:00 AM
Well, a friend of mine is selling me the amp for 100NOk, aprox $17, brand new in box. Sounds like a good project to me. Now I have to build myself a suiteable power supply. calculating from the watts

150w/14,4V = 10,41A

10,41A to runit bridged with a 4 ohm load on 14,4V. Since the VA rating and W is equal, the absolout mininmum transformer I could run it on is 150va



20A*14,4V = 288VA
The amp has a 20 A fuse, wich tell me that the amp will never use more than 288VA before blowing the fuse, bridged at 14.4V.


12V*20A = 240VA

14,42 / 12,02 = 207,36 / 144,00 = 1,44.
This gives that the amp puts out 1,44 times the power at 14,4volts. It probably only use about 60% of the PS to amplify, wich means 390Va.......

150W *0,56= 84W

I'm planning on running it bridged on a regulated 12v supply, wich gives me a max consumption of 390VA, and a wattage of 84W RMS.

So what I should be looking for is a transformer with 240V primaries, 9-15V secondaries (it will be rectified and regulated at 12V) and a VA rating abowe 390Va, right? Thats kind of hard tol find....
#53
Amplifier Discussion / Using car HiFi amps
June 18, 2007, 10:00:05 AM
Would it be possible to use something like this with guitar?


Specs
Distortion:                            <0,08 % THD at 2ohm
                                          <0,1 % THD at 4ohm
Frequenzies                           20 Hz -20kHz +/-0,5dB
Dampening                            >95dB
bass boost                            +8dB, centered around 45hZ
Input impedance                     20kOhm
Input sensitivity                      150mV - 8V
Output impedance                   Stereo: 2-8 ohm
                                           Bridged: 4-8 ohm
Dc input                                10-16 V


RMS                                     2 x 50W at 4 ohm and 14,4 V
                                           2 x 75W at 2 ohm and 14,4 V
                                           150W bridged at 4 ohm
Max power                             200w bridged at 4 ohm
Fuse                                     20A


Protected aginst shorts, to high dc and overheating.

Looks like a typical poweramp to me, and the chassis is made of tinned aluminium. Would it be suiteable with guitar ,bridged for mono and high power with the right preamp?
#54
I have sent my girlfriend and daughter home to my mother in law for about a week, wich has given me time to finnish of my stereo LM 1875 amp. I'we done all the offboard wiring now, and everything should be ok. I'we added a volume pot at the input, and it works ok when it comes to control volume. However, when I turn it down, my chips start to clip, like it does when it's getting to hot. Sort of like a hard tremolo. when playing above half the volume, I don't have this problem, and I don't have it when I use the volume controll on my Behringer gdi21, wich I use as a preamp.

The amp sound fantastic, anyway, but it would be great to be able to controll the volume, as it is plenty loud. Could it be low freequenzy oscilaion? Ground loops?

Some pics, just for fun. The pics are taken with a cell phone-camera, so this hing looks a lot better in real life.


Gutshot. Wiring looks messy here, but is in fact pretty neat.


Another gut shot


The fan and led controlling circuit


The volume pot in question


The input and outputs


Power switch, fan and led

#55
Amplifier Discussion / Drill sizes
May 09, 2007, 09:38:28 AM
Might be usefull here too....
Drill sizes for common components, like leds, pots etc....
www.syndromet.com/drill.doc
#56
Yes, I did. My keybord is almost out of battery, so I have to go back and fill in all the missing letters.
#57
No, I was actually refering to a plastic piece. I meant the little thing that isolated the screw from the chip. That little part that goes through the hole in the chip, you know... Luckily I found it again, so things are all good. Been playing my LM175 with a sans amp up front all day. Sounds superb!!!!
#58
I lost one of those little plastic isolators that you use to isolate the chip from the chassis when you mount it, and I don't have anyone in spear. Is there anything else that can be used? Anyone have any good ideas?
#59
Search for "jensen mod" in google. Very cheap, high quality guitar speakers. I really suggest you use  guitar speaker intead of a general purpose speaker. I'm about to make myself a cabbinet too, and I'we decided to try to copy the ones Geezer make. A quick search on geezer would give you the measurement for a 1x12 cabinett at least.

When it comes to enblosure building, you should read this:
http://colomar.com/Shavano/construction.html

other useful links
http://www.geezersoundco.com/

http://www.tubedepot.com/jenms.html

http://www.loudspeakersplus.com/html/jensen_mod.html

http://stores.ebay.com/jam4Jaudio_carpet-tolex-grill-cloth_W0QQcolZ4QQdirZQ2d1QQfsubZ6QQftidZ2QQtZkm
#60
As Joe said, the little Gem is a great amp,but it will only give you overdriven tones. I would therefor recomend something that will give you clean tones as well. As far as I know, both the cricket, the ruby and the massberg enter clean territory. I love the Gem (use it more than any of the other amps), but it really only gives you that cranked classic rock tone. I also have a fetzer-ruby, and it is fairly clean and fender like and goes into blues-breakup style overdrive. To get into rock tones I need to push it with a booster or an overdrive pedal. From what I'we heard, both the cricket and the massberg cover everything from clean to massive overdrive. That makes me think they are more suiteable, since you don't know what kind of sound your son wants.

With the part count from the ruby, gem and cricket, I rally sugest you build them all, and see what you like the most. Whatever you chose, I'm pretty sure your son will love it. ;)