Well Joe, here's another thing to ponder. With my acoustic guitar plugged into the Ruby,it sounds great going through the 6" whizzer cone speaker. No need for a guitar speaker there. :tu:  Why? Hmmm..... it might have to do with the type of pickup that's mounted in my acoustic?  Maybe it's some type of mic so the amp is acting like a PA system?

That's exactly how my ruby sounds through a good 12" guitar speaker. I built mine inside of a cheap 6" bookshelf Hi-Fi speaker to take camping with my son and I. I put a speaker out jack in it.

It sounds a lot like this clip when played through the HI-Fi speaker.
http://www.youtube.com/watch?v=3ipDpaOGMLw&feature=related

Funny how there are still a lot of people who think that a guitar speaker is just an over priced ripoff. Or,it can't make THAT much difference - well, it does.

You'll be amazed at how good and loud the Ruby will sound when played through a high efficiency 12" guitar speaker, say 98-100db SPL. There is an extreme tone and volume difference between guitar and Hi-Fi, car,bass or PA speakers. Sure, they all work with guitar amps, but never sound right. Most important, especially with small amps, is the efficiency rating of the speaker.

Even a high end Hi-Fi speaker will sound bad with guitar as you have already found out.

Beware of using 8" speakers from small commercial guitar amps. Many of them sound terrible and are not even voiced for guitar(I have one of these in my Peavey Rage). Rowdy mentioned the Jensen 8" Mod speaker. That is decent sounding for a small speaker. A much better choice would be the Mod 12-70. It would be much louder and fuller sounding.  There are a lot of very nice guitar speakers in the 50.00 to 100.00 range. I think Eminence makes some of the best speakers in this lower price range.

Don

Well, The amp IS now loud enough to play with drums. It does need to be turned up to about 2 -3:00 to get there,though. Very good clean and semi-dirty tone. I'm really surprised that it sounds this good. I'm also playing it through a 98.7 db SPL speaker,so that helps a lot with the volume.

My 16 year old son doesn't like it too much. Says it just doesn't cut it with the distortion tone. He's spoiled rotten. He's been playing exclusively through tube amps since he was 11.   What did I have for a guitar amp when I was 11? A cheap broken battery powered tape recorder that I hacked into a guitar amp. Sounded so good through that 2.5" speaker! Those were the days!  We were poor,we had to improvise or go without.

Quote from: joecool85 on December 09, 2010, 11:58:14 AM

Also, you can up the gain of the TDA2050 by adjusting R2 or R3 on the datasheet schematic.  http://www.datasheetcatalog.org/datasheet/stmicroelectronics/1461.pdf

Well, I changed R4 from 680R to 470R and the gain went up quite a bit. I'm running it back at 18V single supply now. The bottom got bigger too. It sounds quite nice!

I suppose the component values on the data sheet are optimized for a 18V dual supply. Is there another component value that I should experiment with?  It sounds much better than my Peavey Rage. Although that's not a fair comparison because the Rage comes with an 8" speaker that was clearly not designed for a guitar amp.

Also, the component numbering on the 2050 datasheet is different for single supply vs dual supply.

This has really been a fun experiment - so far.

Ok Enzo, the guitar puts out about 150 mv ac. The preamp puts out 2.3 V at full gain but that's usually too much distortion for me. At half gain,where I usually play,it's putting out 1.2V. If I bypass the preamp and play directly through the power amp, the volume goes way down, as one would expect.

Quote from: Brymus on December 09, 2010, 04:10:42 PM
Hey Bigbeck
I remember you from SEwatt.com
welcome to the board.
Be sure to check out DIYstompboxes too,lots of good people there,Joe Cool included.

Brymus, What's wrong with you? Don't you think there could be other Bigbecks out there? WTF! What is Sewatt?  :lmao: I had to say that as I don't remember ever insulting you over there.

Thanks for the welcome.

Don

Joe,

Any suggested values to start with? For R4 I have 510,470 and 330 ohm. The stock resistor is 680 ohm. For R5, I have many choices from 27K to 2.2 meg. The stock resistor there is 22K.

Don

Ok, I found an old Radioshack 12-0-12 2 amp transformer in my garage, hooked it up to a full wave bridge and got 35.8 volts. The chip gets hot now! The transformer gets a little warm after 20 minutes of full volume playing,but not hot. I got some increase in volume so it should be able to keep up with a conservative drummer. We'll see. It's about as loud as a 5 watt tube amp. Of course it doesn't sound as good as a cranked tube amp, but I never expected it to. I'm going to use it mainly for low volume jamming and solo practice. For that,it's perfect.

Thanks guys,for all your help,

Don

Quote from: Enzo on December 08, 2010, 11:29:32 PM


I have no idea what level of signal your preamp produces, do you?  

No,I don't. But here's a link to the preamp I used. I tried the amp both with and without the preamp and there's quite a big  difference in volume. I would say this preamp almost doubles the volume.  http://www.runoffgroove.com/eighteen.html

I just picked up a 24V 2.7 amp laptop PSU for 8.00. Hopefully,that will help a little. If that doesn't give me enough gas, I guess I'll have to spring for a 24V transformer. That should give me 34V after rectification,right? Will 3 amps be enough or will I be able to get away with 2 amps?

I still can't get over the huge amount of current these tiny chip amps draw compared to tubes.

I'm new to SS electronics but have built about 15 small tube amps from 5 watts to 40 watts in the past 4 years.

So I built a single supply TDA2050 amp with a ROG "Eighteen" preamp. I used a 15v 1.6 amp wall wart that supplies 17.5 volts with the amp at idle. Overall, I'm quite happy with both the clean and distortion tone. I did expect it to be louder,though. Right now it's not putting out as much volume as my 5 watt tube amps. It's almost loud enough to play with drums - but not quite.

Maybe I botched up the build? I tried lowering the voltage to 14.5 V and the volume went way down and it sounded real bad so I took it back up to 17.5V. Next,I tried using two 12V motorcycle batteries in series, figuring I would get even more volume, but it sounded about the same. Maybe a little more clean headroom.

I used half of a CPU heat sink on the chip and even after10 minutes of loud playing it only heats up a few degrees past body temperature and I can only feel the heat if I put my finger directly on the chip. The heat sink itself,does not heat up. Hmmm... I thought these chips were supposed to run hot? I'm using this amp with a 4 ohm Fender guitar speaker.

My main questions are: Does a single supply only allow the chip to produce half of it's rated power? And why is the chip running so cool? It sure sounds good,though. Oh,one other thing, I mounted the chip in an IC socket so I could try out a TDA2030 and LM1875 too. Maybe that's part of the problem?

Don