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Hello Mike, How much feedback are you using? 800k is a large value for a feedback resistor!! See the ringing on the 3kHz square wave? What you want to do is use a 10kHz square wave and change the cap value until the ringing is mitigated.

Have you contacted Bob Crites?

Perfect height, you know.......for bowling

Happy Belated! I am always late to the party.

The thread isn't locked and I saw people discussing something the president addressed to our country last night and I am participating respectfully. Since a moderator has now come in to assert control we will now fall back in line like good little members.

Hold the phone here. The original post is asking what terrorism is. Fair question. If someone says part of the solution is gun control then there needs to be guns somwhere in the defintion of terrorism. It's like balancing equations.

People argue over crossovers and those threads get locked. I kinda thought these forums were to discuss things as long as people don't get nasty? I can see if a thread gets locked for people to cool down and then threads get deleted if they are malicious in nature. This is all relevant current events going here in our world around us. With that said I will shut up.

Do I sense sarcasm? I have thought about this, and it's the only thing that fits the bill. If this country was so determined to save lives cigarettes and booze would be illegal, they by far take more lives than terrorists ever did or will. You have a far better chance of dying in a car accident than by a terrorist, yet people are not scared to text and drive at the same time with no fear of death. People are so scared to die from terrorists, as they smoke a cigar and sip poison. The agenda is take power and wealth away from the masses, they already have the wealth next is the guns and freedom so we are powerless. Between gun laws and the patriot act you could never start a revolution.

Hello Marty No need to apologize for great questions, if they don't get asked then nobody learns. In the schematics V1 and V2 are voltages, in my simulation software they are in the sense perfect voltage sources (for now anyway). V2 is the input signal in AC volts (you were right!) and V2 is the high voltage B+ created by the power supply. You can see for V2 when I do an AC analysis it uses .1 volts peak amplitude and sweeps through whatever frequencies I choose, say 1Hz to 1MHz. Under that you see sine 0 .6 1k, this is for transient analysis, it is a sine wave with 0 volts DC offset, .6 volts peak amplitude, @ 1kHz. You may have noticed I don't have schematics for the power supply yet, we will work on those after we know what kind of circuit you plan to run. After we design the power supply I could add in their parameters like 120Hz ripple from rectifier, output imedance, etc...... to the simulation. I ask you then, what are your requirements? We can start with simple goals like power out, bandwidth, distortion, and damping factor. So you could say something like; "I am looking to build a push pull amp that has at least 5 watts of power, I want full power down to 34Hz for my Cornwalls with distortion <5%, and a damping factor of at least 2. Push pull designs cancel the second harmonic that is created in that stage. In the second schematic I presented the input SRPP stage has low distortion when optimised so looking at the FFT chart I plotted you can see that the second harmonic is low, this circuit has much less distortion in open loop than the first I presented. The reason the first schematic has less distortion is because I had more open loop gain to add more feedback which cancels distortion. The first stage in the first schematic is a common cathode gain stage and is rich in second harmonic, if this stage was more linear the FFT would look like the second amp with mainly a dominant third harmonic. What I am getting at is you can taylor your distortion to how you like, you said you wanted a push pull amp and in my experience push pull amps tend to have more third harmonic. Why? Well most of the distortion will be created in amps is in the output stage and like I said earlier the second harmonic distortion in a push pull amp gets canceled so the third dominates. The first schematic I presented is a push pull amp but with a distortion spetrum similar to single ended. I didn't want to present two schematics that had the same distortion spectrum. You can even name amps you have heard before and really liked and we can not copy the schematic, but copy it's characteristics and using your parts come up with a similar sound!! Our own Carver challenge, sort of. Pick your flavor I hope others join in on the discussion. I know Maynard has been following.

https://www.youtube.com/watch?v=girnJH7tvpM - Frank Zappa

In high school we used to follow Phish around and drop acid. There was a lot of "gel tabs" around, those were my favorite. For experimental purposes I ate around 10 or so in one sitting a couple of times........big doses are something entirely different than recreational doses. I don't do that anymore that's for sure. Jimi: "Have you ever been experienced?" Me: "Yes, I believe I have"

Two words..... NITROUS OXIDE

They are really fun and a kid can learn a lot about mechanical things from them. I don't own any (I have no kids) but one of my friends does and they are fun!! Even for us adults!!! My friend isn't mechanically inclined so I end up working on them for him, I kinda stopped because I thought the kid who is 12 should be able to do most of the stuff by now but he just can't get the hang of it. He sure can break them real good though! You can upgrade the plastic axles and drive shafts to metal ones so they don't break as often, they still get damaged......bent....etc....over time. If you are mechanically inclined and don't mind doing some occasional repairs, upgrades, maintenance I would say go ahead and get one they are fun.

Okay I had some more time this morning to look over some of my ideas. I am sure there are mistakes so please I need other tech eyes to look them over. First one is common cathode stage driving a cathodyne phase inverter w/ fixed bias so there is no bias resistor in the cathode messing with the balance. Output stage is ultra linear class A/B with cathode bias. R15 and R16 is a 50 ohm pot for DC balance, since the models are perfect it is set in the middle for simulation. 10db of global feedback. Full output is around 10 watts @ .5% THD Schematic; FFT @ 1 watt, .1% THD mainly second harmonic from input stage. The second schematic is a bit more fun if you don't need a lot of power and want to try something a bit more exotic. First stage is an SRPP driving a self inverting Class A push pull output stage. I like the SRPP because you will not get degraded performance with older valves that have lower transconductance, basically tube age will not effect performance. Since we need to force Class A operation there is half the power. Elegant and simple if you ask me, no phase inverter to worry about AC balance. R15 and R16 serve the same purpose and will be replace with one of these: http://www.mouser.com/ProductDetail/BI-Technologies-TT-Electronics/93PR50LF/?qs=sGAEpiMZZMvygUB3GLcD7jZSyzxDqivkwIQj05pIUWQ%3d Or any similar pot will work. I want to mention that it might be a good idea to place 1 ohm resistors in series with the power tubes cathodes as current sense resistors, these are easy to add and I recommed you do. 6db of global feedback. Output power is 5 watts per channel @ 1% THD. Schematic; FFT @ 1 watt, .2% THD

I am still cooking something up, I have a real simple schematic good for about 10 wpc with really low distortion and decent damping that should work perfect with the $30 Edcors found here; https://www.edcorusa.com/gxpp10-8-8k Stay tuned

PM sent.

I can't tell if you are agreeing with me that there is not an impedance mismatch or if you are trying to say there is? Chris asked if the CD player has enough volts to drive the active crossover. My answer was yes it does provide enough voltage and I demonstrated why mathematically. I think we agree, but you may or may not have misread my answer. Yes we agree this should work. In fact I stated this is how all line level audio equipment works. We are striving to get 100% efficient signal VOLTAGE transfer from an output to the next input. This is done by having a low output impedance driving a high input impedance. But by definition this is an impedance mismatch. I figured we were in agreement I think initially I misread your post so for that I apologize. It sounds like juniper has things squared up now which is good. Between fixing the input grounds and adjusting for the amplifiers gain difference he should be rocking!

I didn't read through all of the posts but if your amp has an rms power of 125wpc that might be into an 8 ohm load. Your speakers might dip down to 4 ohms at lower frequencies, that is the problem. With a low impedance output amplifier you are now almost doubling the power to 250 watts!

I can't tell if you are agreeing with me that there is not an impedance mismatch or if you are trying to say there is? Chris asked if the CD player has enough volts to drive the active crossover. My answer was yes it does provide enough voltage and I demonstrated why mathematically. I think we agree, but you may or may not have misread my answer.

That's an understatement. He's so precise. Thanks for posting. Hey Carl, I am glad you liked the videos. I like how Edson proves that age isn't a factor, older musicians can still be at the top of their game. I have been playing for about 20 years and I can only hope that at that age I am still alive and can play at a fraction of his capacity.

I know I love his facial expressions, he seems so happy to play. And yes he makes it look so easy.

If the active crossover you speak of is the DX-38 then yes, it has an input impedance of 20k. Think of the thevenin equivalent for the circuit. The output impedance of the CD player is <10 ohms, lets say 10. His CD player puts out 2Vrms I believe he said so plug the numbers into the voltage divider equation; 2(20000/20010)=1.99Vrms That's the benefit of an active crossover, they are much easier to drive So clearly there is no impedance mismatch. Also in the DX38 manual it states that with a nominal input voltage of 1.55V it will put out a nominal 1.55V, it has unity gain up until you drive it with more than 8.7V then it will attenuate and keep the output voltage at a max 8.7V.