Shooting for the moon, huh? Fender Twin is all about a loud and clean sound. A 5W amp won't cut it. Anyway, if your aiming for good clean tones I'll probably like your amp. You can always add dirt later but a stompbox won't fix crappy clean tones.
Yeah but as you get older everything seems to be too loud. (cue in Pursuit of Happiness, I'm an Adult Now).
I was thinking along the lines of the Belton reverb modules sold by AES. The data sheet you linked has two conflicting schematics in it, and no one seems to have the device anyway. I won't know what the power supply can do until I build it and torture it. The 15 mA or so the Belton device needs is no problem.
About 15 years ago I made a SS guitar amp using a HiFi preamp chip that had tone controls, a graphic eq chip, and a 75 watt chip amp. Both the tone control chips were SPI programmable. The knobs were mounted on Panasonic rotary encoders and everything was controlled by a PIC microprocessor.
The sound quality wasn't great but that wasn't my objective. I got all the chips for free as samples and I wanted to explore the ability to store and recall setups. That part of the deal worked great.
Lets say you have a very flexible tube amp with maybe a dozen controls. It might take a week of tweaking to find exactly the right tone for a particular riff. Then you tweak all over again for the next sound. Thats OK if you have hours of studio time, but if you pay for studio time or play live, storing and recalling sounds would be cool.
That is what I was thinking of, but I am not exactly how to do it all yet. Unlike the DSP magic, this stuff is all within my scope of abilities. It will just take some tinkering, and a cheap tube amp that I don't mind blowing up.
Aha a shower moment.
I realized it had to be PS related and not a tube oscillation as it is too low. So I stuck a 5uFd cap on the power terminals and it shifted to 65KHz.
I had tied all the B+ connections together and was getting PS feedback from the output stage loading the supply as it is on a tube lab breadboard.
I'll fix it tomorrow night (or this evening actually).
I realized it had to be PS related and not a tube oscillation as it is too low. So I stuck a 5uFd cap on the power terminals and it shifted to 65KHz.
I had tied all the B+ connections together and was getting PS feedback from the output stage loading the supply as it is on a tube lab breadboard.
I'll fix it tomorrow night (or this evening actually).
Quote:"Lets say you have a very flexible tube amp with maybe a dozen controls. It might take a week of tweaking to find exactly the right tone for a particular riff. Then you tweak all over again for the next sound. Thats OK if you have hours of studio time, but if you pay for studio time or play live, storing and recalling sounds would be cool."
Mmmmh, sounds like the Mesa Triaxis Preamp to me (I know there are other Midi-programmable products from other vendors as well)...
Been there, done that. Though a one-channel amp with just one great tone has a lot of charm, too.
Martin
Martin
Mmmmh, sounds like the Mesa Triaxis Preamp to me (I know there are other Midi-programmable products from other vendors as well)...
Been there, done that. Though a one-channel amp with just one great tone has a lot of charm, too.
Martin
Martin
Yes, I have an old ADA MP-1. Works good when it works. Quite microphonic though.
The thought was for future expansion, but after blowing things up twice last night, I have decided to just get the one channel amp working. The +/- 12 Volt supply has been abandoned for now.
I'm up to 147MHz on the oscillation. Time to try a cap/resistor across the anode resistor. I suspect I may be picking up the local 2M repeter.
Anyone find a low cost inductor for the power supply? I'm considering re-stacking the lams in a $4 xfmr, but will be a pain in the A--. For special effects, I have decided to make the amplifier clean, but include a $1 beam deflector tube for dial-in harmonic generation.
finished 5F1 clone, uses 12W6 tube output, 12ax7 pre and 5y3 hybrid rect:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I have a friend that has been looking to build a cheap practice amp. I was thinking of a 5F1 circuit but using a 6AY11 in place of the 12ax7 and using the beam pentode of the 6AL11 as the output tube. Total output power will be lower than with the 6v6gt but with a total of $2 invested in tubes he can purchase a few sets to keep around. A cheap edcor SE transformer and a suitable power transformer from either edcor or perhaps antek.
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I went to order some extra P-T291 transformers today, ... AES showed them in stock but when they went to pull the order there were none.
Who knows how long it will be on back order.
Who knows how long it will be on back order.
Same thing happened when they had their tube sale a few years back. I opened my mouth about some cool $2 sweep tubes that made over 100 watts, and poof they were gone before I could get more, yet they still show stock. They showed 6BQ6's for 98 cents each for a year after the sale, but you couldn't buy any. Now, 3 years later they have raised the price to $1.30, but you still can't buy any. Their inventory control system must be a white board in the back of the warehouse somewhere.
The P-T291 that I got is 3 years old and has been banged around a bit, but they just dropped it in the box. The box travelled about 5000 miles to get here going from Arizona to Florida through California, Oregon, and Kentucky. The speakers made it OK.
I have wired up 3 of the 5 tubes in my amp so far. The 3 easy ones, P-P output and PI. Nothing blew up, but there is some 120 Hz hum. I fixed it for now by adding a 470 uF cap from B+ to ground. It's to expensive for the final design. A few resistors are getting too hot to touch too.
I get a whopping 3 watts at 3% distortion. Frequency response is +0 -3db at 32 and 9000 Hz. I am using a 12 VA heater transformer for an OPT. I will try the P-T291 tomorrow.
I haven't measured distortion, but from the waveform on the scope I think I'm hitting 1.02W at about 10%thd into 8 ohms with a junk transformer, It looks like mostly 2nd harmonic.
"The Bedroom Troubadour™" is up and running.
I'll clean it up tomorrow and take some measurements.
The "Dial-a-Tone™" control works.
"The Bedroom Troubadour™" is up and running.
I'll clean it up tomorrow and take some measurements.
The "Dial-a-Tone™" control works.
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I probably did that. They jacked the price right after I started posting about the 40W monoblock I designed with 6BQ6s.
Somehow I dont' think people will go nutso over buying tubes to build 1-5W guitar amps like they did over 40W amps with sweep tubes.
But one never knows.....
But one never knows.....
I also posted some of my results from screen driving them to 110 watts before they blew up. The other tube vendors didn't have a supply problem with those. ESRC has over 3000 currently in stock but since they do sell (slowly) he won't go too low in price. I did get a box of 87 of them from vaccumtubes.net for about 75 cents each.
I have seen evidence to the contrary. There aren't too many people participating in these discussions, but there are people quietly watching. As you found out the supply of P-T291's has dried up.
I found out about a 12AX7 with an odd heater voltage, and all the tube vendors show them for around $4. Some phone time revealed that they are in short supply, and there has been a run on them in the last two weeks. Somethings going on.
I have been getting email for years asking for a Tubelab Simple Guitar Amp. That email has gone WAY UP in the last two weeks. Of course most of the email wants a 100 watt head for $99, but there is interest.