What do you think about transconductance power amplifier for current-drive loudspeaker?
JAES,vol.37,¹3 p.129-148 ; ¹10,p.809-822 1989
JAES,vol.37,¹3 p.129-148 ; ¹10,p.809-822 1989
Building this one is high on my list but it is a complex one.
I have build an active 3-way speaker using 10W class A current drive amps (from Electronics World & Wireless World). Sounds good, but if it is better then normal voltage drive is another question. I looks as they are difficult to get stable. I had oscillations all over the place (60kHz up to 1.6MHz).
Problems are: you have to go active, you lose all damping of the woofer so you need active correction.
If you want to try, the EW&WW amp is much simpler (read: cheaper) and has some scope for experiments. Let me know if you are interested, I'll search the reference.
I have build an active 3-way speaker using 10W class A current drive amps (from Electronics World & Wireless World). Sounds good, but if it is better then normal voltage drive is another question. I looks as they are difficult to get stable. I had oscillations all over the place (60kHz up to 1.6MHz).
Problems are: you have to go active, you lose all damping of the woofer so you need active correction.
If you want to try, the EW&WW amp is much simpler (read: cheaper) and has some scope for experiments. Let me know if you are interested, I'll search the reference.
You may find the following articles of interest, unfortunatly they aren't available on-line:
DISTORTION REDUCTION IN MOVING-COIL LOUDSPEAKER SYSTEMS USING CURRENT-DRIVE TECHNOLOGY,
Mills, P.G.L., Hawksford, M.O.J.,
JAES, vol.37, no.3, pp.129-148, March 1989
TRANSCONDUCTANCE POWER AMPLIFIER SYSTEMS FOR CURRENT-DRIVEN LOUDSPEAKERS,
Mills, P.G.L., Hawksford, M.O.J.,
JAES, vol.37, no.10, pp.809- 822, October 1989
regards
James
DISTORTION REDUCTION IN MOVING-COIL LOUDSPEAKER SYSTEMS USING CURRENT-DRIVE TECHNOLOGY,
Mills, P.G.L., Hawksford, M.O.J.,
JAES, vol.37, no.3, pp.129-148, March 1989
TRANSCONDUCTANCE POWER AMPLIFIER SYSTEMS FOR CURRENT-DRIVEN LOUDSPEAKERS,
Mills, P.G.L., Hawksford, M.O.J.,
JAES, vol.37, no.10, pp.809- 822, October 1989
regards
James
OK, I'll search for it. It may take a couple of days, so don't think that I forgot, but at the moment I'm moving all my stuff (I bought the appartment 3 years ago, so it's about time). Otherwise I will redraw it from the pcb by the end of the week.
Sorry Alex, I found the article but there is no date on it. Most I can say of it is that is from before 1996 (then I made my pcb), is called "Transconductance amplifiers" by K. Lewis p580-582 in Electronics& Wireless World.
I'll try to mail you a scanned copy, as the file is to large for an attachement to this forum.
I'll try to mail you a scanned copy, as the file is to large for an attachement to this forum.
Years ago High Fidelity had a article on this subject (80 - 90's). Yes It did not have flat response, based on their measurement. Their was pros and cons.
The article was in danish. I do not have it but i think it you can order it!?
The article was in danish. I do not have it but i think it you can order it!?
Well, the flat response is only a problem if go down in frequency. Because of the output impedance >10k there is no damping. For a good midrange or tweeter, this isn't a problem. And if you do some active correction, you can get a woofer also under control, but then the question is if it is still current driven.
tvi said:
I'm sure I stumbled across Mr Hawksford's homepage at one point - on which there were links to all his published works on distortion reduction in .pdf format. Unfortunately I can't seem to find the link anywhere.
Nelson Pass said:
I smell a trick question...
I think I've got one or two... I think I call them tweeters.
If this weren't the case, then what's the F1 for?
Havoc said:
I actually experimented some a couple of years ago, using the danish High Fidelity article as inspiration. It sounded really well. But for other reasons i never finished the project.
Anyway: I might be interested so Havoc - if you have a link to the EW&WW articel or a schematic I would very much like to see it.
i'm experimenting current amplification to my speakers.....
now i'm thinking about a modification of the LM4780 ti ibtain a current amplifier.
see my 3D.
thanks
max
now i'm thinking about a modification of the LM4780 ti ibtain a current amplifier.
see my 3D.
thanks
max
Re: I have got
can u tell us more about it?
possibly amp schematics & (dedicated?) speakers details... as well as your comment on the sound as compared with other conventional systems.
Tnx.
Alexamp said:
can u tell us more about it?
possibly amp schematics & (dedicated?) speakers details... as well as your comment on the sound as compared with other conventional systems.
Tnx.
Perhaps you haven't seen it, but I have two articles on the subject,
"Sensitive Full Range Speakers and Current Source Amplifiers"
and
"Crossovers for Current Source Amplifiers"
(I think these are the titles)
You can download them from www.firstwatt.com
"Sensitive Full Range Speakers and Current Source Amplifiers"
and
"Crossovers for Current Source Amplifiers"
(I think these are the titles)
You can download them from www.firstwatt.com
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