No, I bought that. It was a mad moment in B&Q
Got some funny looks from a couple of builders.
No, I bought that. It was a mad moment in B&Q
Troublemaker here againCressy Snr wrote: ↑Sun Nov 19, 2017 12:04 am The amp is plenty wide enough in bandwidth and the bass goes down through the floor.
The thing was very carefully designed, with particular attention being paid to avoiding multiple rolloffs and phase shifts, that's why the first stage is biased with a white LED plus other factors were carefully considered, such as adequate spacing from each other of the -3dB poles of the driver and output stage.
Having a bad day Steve ?Cressy Snr wrote: ↑Sun Nov 19, 2017 1:28 pm There are too many clever people on here for my limited brain power to ever be anything more than a source of amusement.
at least we agree on one thing then...snigger
Why would you think I'm having a bad day? not at all.pre65 wrote: ↑Sun Nov 19, 2017 2:14 pm
Having a bad day Steve ?
There are indeed some clever people on here, and I'm glad, because the information they impart has been of great help to those (like me) who really struggle with the theory and maths involved.
And why place so much store in the single forum member who PMs you ? There are plenty more (me included) who have followed your many projects with great interest.
I must have a chat with Nick about the MJ/James D stuff you mention above. I was aware of the need to watch out for close time constants causing oscillation in power supplies, but hadn't tried to do anything like this in a power amp. I can understand how you got the circuit values above, if this was the concern.Cressy Snr wrote: ↑Sun Nov 19, 2017 6:25 pm Now I know feck all about poles and care even less, but MJ for one says that if you make a three stage amp, they become important.
He tells you how to calculate them so you need to consider them or you get an oscillator not an amp. JamesD said long ago about using staged filter frequencies that are ten times the preceeding one so you don't get unusual behaviours within the signal path. These things from experts stick in my head So that's what I did. Simples......except it isn't.
"Ah but you didn't take into account phase shifts from your filters, so your bass will be crap" except it is anything but crap and motors along with PRaT in spades, textures galore and welly unheard by me from any other device I have built. The bass cones flap not a millimetre.
In a vinyl system, you can push the LF low enough to excite resonances in other parts of the system and those can eat power and cause bad sound, overload etc. Cascade issues with RC filters can cause ripples like they do with different filter types. Is a ripple that is seen in some filter types a resonance? Are beat frequencies in power supplies that lead to motorboating a resonant RC filter interacting? This can be an issue in a two stage amp never mind a 3 stage. Are these just different names/terms for resonance?IslandPink wrote: ↑Sun Nov 19, 2017 9:15 pm Stephen, do you believe that RC filters in different parts of a power amp interact with each other in a resonant way ?