One thing about class A's tubes or even a-b's is you don't need anywhere near the same output that you will with the solid-state versions. 40 watts will blow people out of their seats in most places. Past that point you will probably want to just mike the amp. Might need over 100 watts if you used the solid-state version of the same amp to get the same output. To give you an idea of what a good tube amp will do I've been building a class a with the thumpin output of 3.2 watts!. This is for buddy of mine who plays blues. Mind you it really depends what you are playing as far as how you build/tweak the amp. If your using 5881's I take it you are intending on doing some crunchy ear bleeding loud rock? He claims it will be enough for any small gigs and it will allow him to crank it up to get into distortion without blowing people out of the room. He's really anxious to try it out for their next recording session as the Champ they use gets too loud at 4.8 watts. I happened to get a pile of nos and milspec tubes given to me so we're using those instead of the usual EH/Sovtek stuff. Dave -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf Of Mark E. Skeels Sent: December 19, 2006 8:14 AM To: Microcontroller discussion list - Public. Subject: Re: [OT] Buikding a tube-based guitar amp Hi, Rich, How did they turn out? What config did you use? I noticed a lot of tone variation between amps so far and I'm kind of unsure right now as to what causes that. I've read that bypass caps on the preamp tubes have a lot to do with this. Also, I'm unsure of how big an amp I'd want to make, given the different configs. All the amps I've played until recently use push pull OP stages and there 40 to 50 W RMS is enough, but with a class A I'd probably need more output stage to achieve the same results. That seems like a good tip on the DC filament supply, thanks. Mark Rich wrote: > I have built several tube amps. The circuitry is easy . The output > transformer is an important consideration, A common output tube is 6L6, but > I have used 5881. But there are other good tubes. The beam power pentodes > have some advantages. Some output transformers will have taps for the screen > grids. It is referred to as the Williamson design. I bet you can find a lot > of info on the net. If you cannot, let me know and I will see what I can > come up with. Also, the schematics for Fender, or Gibson or others is > probably available. If you use DC on the filiments you get rid of some of > the low hum, especially if you use power transistors in a capacitance > multiplier configuration. But some people want the hum. It will be > interesting to see how you progress. > > > > ----- Original Message ----- > From: "Mark E. Skeels" > To: "Microcontroller discussion list - Public." > Sent: Tuesday, December 19, 2006 9:00 AM > Subject: Re: [OT] Buikding a tube-based guitar amp > > > >> James, Tony, Dave and Patrick, >> >> Many thanks for all of the input. >> >> I'll keep you posted; it'll likely be a bit slow moving project because >> of other commitments. >> >> Now does anyone know of any good references on tube guitar amps and >> audio circuitry? >> >> Remarkably, this is one area where tubes do actually seem to produce >> superior sound. >> >> I've been doing some research on the internet. I found out that in >> addition to their characteristic distortion, which many guitarists >> prize, it turns out that their response to transient input is can >> actually sound cleaner and brighter than transistors. They have a softer >> response to the transient and that tends to smooth out the response and >> avoids the introduction of clinky sounding even harmonics, or so I read. >> I would post the link for this, but I lost track of it. It had to do >> with an audio engineering firm tasked to improve the lousy sound of a >> large mixing board in a recording studio. Frustrated that nothing was >> working, they tried a tube preamp and incredibly the harsh sound of the >> board went away. After a bit of analysis they found it had to do with >> this initial transient response of the SS preamp in the board vs. the >> tube preamp. >> >> I have verified this by placing a Fender HotRod Deluxe tube amp side by >> side with an older Fender Princeton Chorus and noted not only the >> greater richness of the sound but the sparkly quality in the tube amp. >> Compared side by side, the solid state amp really does sound harsh and >> grating on the attack. >> >> Visiting some local music stores this last couple of weeks I have >> learned that not all tube amps are this good. For instance, I played >> some Epiphones that sound really muddy and "blatty." The Vox AC30 (class >> A) sounded particularly good to me. >> >> There are push pull, class a, and class a/b models. all have their >> unique character. It will take some time to really figure out what I >> like out of what's available. >> >> All of this has led me to become interested in tube guitar amps and to >> consider experimenting with some of my own designs. The first step will >> be to learn some more about tubes. It was a subject not broached in my >> classes at school. >> >> I may start here; an open source tube amp design: >> >> http://www.torresengineering.com/freplantomak.html >> >> This seems to be the premier resource on tube guitar amps: >> >> http://www.torresengineering.com/inbydantor.html >> >> Mark >> >> Dave King wrote: >> >>> Mark >>> >>> Look around some of the online Amp shops. They will sell you a new old >>> stock >>> or reproduction plate for far less than you can do a one off. >>> >>> Dave >>> >>> -----Original Message----- >>> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf >>> Of Mark E. Skeels >>> Sent: December 18, 2006 7:14 AM >>> To: Microcontroller discussion list - Public. >>> Subject: Re: [OT] Restoring vintage Gibson GA-9 guitar amp >>> >>> >>> Actually, I took a little closer look and graphics on the chassis is >>> just a silk screen. It's not stamped. So I guess unless I can find a new >>> silk screen, I'm out of luck....... >>> >>> Mark >>> >>> Mark E. Skeels wrote: >>> >>> >>>> This old amp has a chrome plated steel control panel that is stamped and >>>> >>>> then some kind of ink is put into the depressions for letters, graphics >>>> patterns, etc in the depressions. >>>> >>>> Most of the ink is worn away. >>>> >>>> Does anyone here know how that is done and what kind of ink to use to >>>> restore the graphics to the front panel? >>>> >>>> Thanks, >>>> Mark >>>> >>>> >>>> >>>> >>>> >>> -- >>> http://www.piclist.com PIC/SX FAQ & list archive >>> View/change your membership options at >>> http://mailman.mit.edu/mailman/listinfo/piclist >>> >>> >>> >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> >> __________ NOD32 1928 (20061219) Information __________ >> >> This message was checked by NOD32 antivirus system. >> http://www.eset.com >> >> >> >> >> -- >> No virus found in this incoming message. >> Checked by AVG Free Edition. >> Version: 7.5.432 / Virus Database: 268.15.24/592 - Release Date: >> 12/18/2006 1:45 PM >> >> >> >> __________ NOD32 1928 (20061219) Information __________ >> >> This message was checked by NOD32 antivirus system. >> http://www.eset.com >> >> >> > > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist