Hi,
Just messing around, that is not a good circuit.
In fact a simple series resistor for low Qts drivers works quite well,
with a very easy load. Because Qts is low the impedance peak is
very high and so you only lose < a dB at the drivers resonance.
Probably the way to go for valve amplifiers.
Effect of 6.6R series resistor on voltage drive for modelled driver :
/sreten.
Just messing around, that is not a good circuit.
In fact a simple series resistor for low Qts drivers works quite well,
with a very easy load. Because Qts is low the impedance peak is
very high and so you only lose < a dB at the drivers resonance.
Probably the way to go for valve amplifiers.
Effect of 6.6R series resistor on voltage drive for modelled driver :
/sreten.Attachments
Hi Sreten,
I wonder what phase inversion are you writing about. Driver current ? If at the notch intended to cope with driver breakup beyond which there is sharp acoustic roll-off, then that will not be audible !
Also I sincerely hope you are listening to all of those suggested circuits before you post them. I'm sure you know I often state that simulation can so often be misleading.
I had this T-bass circuit working in real life long before I went anywhere near the simulator to check what was going on.
I also simmed some circuits which appeared would reproduce better, but which in fact sounded inferior, especially with dynamic waveforms.
An 8 ohm resistor in series with a woofer will *sound* like words diyAudio would turn to "****", no matter what anyone's simulations show !
Cheers ....... Graham.
I wonder what phase inversion are you writing about. Driver current ? If at the notch intended to cope with driver breakup beyond which there is sharp acoustic roll-off, then that will not be audible !
Also I sincerely hope you are listening to all of those suggested circuits before you post them. I'm sure you know I often state that simulation can so often be misleading.
I had this T-bass circuit working in real life long before I went anywhere near the simulator to check what was going on.
I also simmed some circuits which appeared would reproduce better, but which in fact sounded inferior, especially with dynamic waveforms.
An 8 ohm resistor in series with a woofer will *sound* like words diyAudio would turn to "****", no matter what anyone's simulations show !
Cheers ....... Graham.
Graham Maynard said:
Hi,
Phase inversion ? that was wrong terminology, I was confusing myself.
Listening to them ? Of course I'm not, its just playing around.
Simulators are misleading ? can be with poor designs,
but used correctly they can also be brutally accurate.
You can design circuits without design ?
All a sim does is remove the tedium.
Build first, sim later is not common sense.
I'm not interested in subjective judgements such as your last
statement, which is simply not true. It is for some cases, other
times it is not, and is therefore not a meaningful thing to say.
/sreten.
Sim the FR first and listen later is not just NOT common sense, but does not reveal dynamic inadequacies !
And that is where this circuit makes a difference, yet by your own words you are not interested in subjective observation.
Different loudspeakers respond differently no matter what you might think you are revealing here.
So pray tell us how you are going to be brutally honest in measuring the performance of the T-bass or your circuits objectively if you are not actually going to drive real loudspeakers with them ???
And that is where this circuit makes a difference, yet by your own words you are not interested in subjective observation.
Different loudspeakers respond differently no matter what you might think you are revealing here.
So pray tell us how you are going to be brutally honest in measuring the performance of the T-bass or your circuits objectively if you are not actually going to drive real loudspeakers with them ???
Hi Mr. Maynard,
I'd like to have an clearer idea how to tune this circuit. So I made some simulations, too. (I know they are far from perfect, but I need a guide.)
I've used SPICE and spread sheet by myself. And the 2 were very different and looked very odd. I won't post them because maybe I got them all wrong in my own spread sheet or also messed up the setting in SPICE... (the circuit looks simple but the mixed relations between transformer, C, L, and load make it so complex... )
According to SPICE, the inductance of the transformer winding plays an important role in the available lift down low. How does this reflect your experience? (You didn't recommend transformers with any particular winding inductance.... )
And, you mentioned the LC tunes the cut, not lift. (I got it now!) So, I can understand decreasing the C, but why did you suggest me enlarge the inductor? That lowers the cut frequency, doesn't it?
I'd like to have a cut around 100~150Hz, what would be your suggestion on LC combinations?
Thanks a lot
I'd like to have an clearer idea how to tune this circuit. So I made some simulations, too. (I know they are far from perfect, but I need a guide.)
I've used SPICE and spread sheet by myself. And the 2 were very different and looked very odd. I won't post them because maybe I got them all wrong in my own spread sheet or also messed up the setting in SPICE... (the circuit looks simple but the mixed relations between transformer, C, L, and load make it so complex... )
According to SPICE, the inductance of the transformer winding plays an important role in the available lift down low. How does this reflect your experience? (You didn't recommend transformers with any particular winding inductance.... )
And, you mentioned the LC tunes the cut, not lift. (I got it now!) So, I can understand decreasing the C, but why did you suggest me enlarge the inductor? That lowers the cut frequency, doesn't it?
I'd like to have a cut around 100~150Hz, what would be your suggestion on LC combinations?
Thanks a lot
CLS said:
The series tuned C+L values you are using (C too high, L a little low) are forming a tuned circuit which loads the amplifier without allowing the driver to optimise LF output.
The C tunes the cut frequency and your 10,000uF tends to form an 'all pass' section in parallel with the transformer, even for bass.
Cheers ....... Graham.
Hi Simon,
Try the one you already have.
Inductors are expensive, yet need to be optimised too.
I cannot really predict in advance which value would be best, here I check first by trying different values in series.
Yes ferrite or iron core will be fine; just go for thicker wire high power versions and you can't go wrong.
Cheers .......... Graham.
Try the one you already have.
Inductors are expensive, yet need to be optimised too.
I cannot really predict in advance which value would be best, here I check first by trying different values in series.
Yes ferrite or iron core will be fine; just go for thicker wire high power versions and you can't go wrong.
Cheers .......... Graham.
Graham Maynard said:
Hmmm......
I said I'm not interested in meaningless subjective judgements.
There is nothing wrong with sensibly applied subjective observation.
Whatever I think I'm revealing ? preceded by stating the obvious ....
the circuit modifies the behaviour of (a) driver(s).
All I'm interested in is what this modification is.
Brutally honest ?
IMO not being familiar with the loading such a circuit imposes
on an amplifier is bad engineering, which ever way you look at.
Your circuit is not rocket science, its a handful of passive components
following the laws of physics and as such it should be, and is, predictable.
A simulator idealises the components but given that proviso the
simulator does show the operation of the circuit, what it does.
/sreten.
