A little boring in my taste.
The bass was good but they lacked details to create a depth in the sound image.
The bass was good but they lacked details to create a depth in the sound image.
I love the idea. Some engineers in here could start a small business selling such niche products. I would love to but I am only half an engineer.
I suspect the potential oxymoron lies in the combination of the phrases 'field-coil option' and 'especially for lower cost units'.
Don't get me wrong: field coils are an extremely good idea, especially for wideband drivers (less practical for multiways, especially if the latter is passive, albeit it's not impossible). But they tend to be more expensive at present than permanent magnet drivers for obvious reasons. That was one of the [pretty much the primary] reasons permanent magnet drivers were developed. No doubt you could get that down with modern PSU types, but how many would take to that is another matter.
Don't get me wrong: field coils are an extremely good idea, especially for wideband drivers (less practical for multiways, especially if the latter is passive, albeit it's not impossible). But they tend to be more expensive at present than permanent magnet drivers for obvious reasons. That was one of the [pretty much the primary] reasons permanent magnet drivers were developed. No doubt you could get that down with modern PSU types, but how many would take to that is another matter.
I had always thought of a field coil as a system engineer's solution. You have current flowing anyway in a tube amp - might as well put it to good use. Eliminates an inductor in the power supply, generates a magnetic field needed by the driver...
Then the cost reductions. A resistor is cheaper than an inductor. Perhaps the cost of permanent magnet materials started to compete with the cost of the coil winding and all the extra cabling and connectors.
I've also wondered if the classic high inductance winding was replaced with a lower inductance / higher current design - what would that do? Certainly modern PSUs can afford to drive amps of current into it, versus the milliamps of the vintage stuff.
Then I wonder what would happen if you could modulate the field in real time? Probably in an attempt to reduce distortion, either in music playing or - if a delay is tolerable - a musical passage coming up. (Of course, sitting in an armchair smoking a pipe...)
Then the cost reductions. A resistor is cheaper than an inductor. Perhaps the cost of permanent magnet materials started to compete with the cost of the coil winding and all the extra cabling and connectors.
I've also wondered if the classic high inductance winding was replaced with a lower inductance / higher current design - what would that do? Certainly modern PSUs can afford to drive amps of current into it, versus the milliamps of the vintage stuff.
Then I wonder what would happen if you could modulate the field in real time? Probably in an attempt to reduce distortion, either in music playing or - if a delay is tolerable - a musical passage coming up. (Of course, sitting in an armchair smoking a pipe...)
Hi,
Of course an FC driver is a wonderful choice and opens up alignment variations impossible with PM motors.
But sadly Mr. Lindgren is right, a commercial new FC driver will never be cheap. Why? Because it will ever remain a niche product, will be produced in small numbers only, and requires more efforts than a PM driver.
Especially if made in Europe, where labour is expensive, a FC driver made in small numbers (probably by hand) will cost a lot of money and will remain a luxury product.
Antique drivers are another story, they´re available for small money.
And if you think that making your own FC driver will be a cheap and easy task, just do it... sorry.
The cheapest new FC drivers from Europe I´m aware of are the offers from SONIDO, SUPRAVOX and EMS. Sometimes I saw offers from China, too, but also these were not cheap.
All the best
Mattes
Of course an FC driver is a wonderful choice and opens up alignment variations impossible with PM motors.
But sadly Mr. Lindgren is right, a commercial new FC driver will never be cheap. Why? Because it will ever remain a niche product, will be produced in small numbers only, and requires more efforts than a PM driver.
Especially if made in Europe, where labour is expensive, a FC driver made in small numbers (probably by hand) will cost a lot of money and will remain a luxury product.
Antique drivers are another story, they´re available for small money.
And if you think that making your own FC driver will be a cheap and easy task, just do it... sorry.
The cheapest new FC drivers from Europe I´m aware of are the offers from SONIDO, SUPRAVOX and EMS. Sometimes I saw offers from China, too, but also these were not cheap.
All the best
Mattes
I will add Lowthers to the list.
You cannot just stick Lowthers in whatever speaker and expect great things. The driver needs to be mated to the right speaker. The impedance of the speaker, which diffuser you use, how to design the speaker box (or horn), and whatever crossover components you desgn all help to get the Lowthers to sound their best. When dialed in, Lowthers sound superb.
Nelson Pass thought that the field coil Lowthers and Feastrex drivers where the best wide range speakers he heard.
You cannot just stick Lowthers in whatever speaker and expect great things. The driver needs to be mated to the right speaker. The impedance of the speaker, which diffuser you use, how to design the speaker box (or horn), and whatever crossover components you desgn all help to get the Lowthers to sound their best. When dialed in, Lowthers sound superb.
Nelson Pass thought that the field coil Lowthers and Feastrex drivers where the best wide range speakers he heard.
I have not heard a Lowther. I did have PM6A in 1976 but in a bad enclosure and a bad amp.
I was very surprised that that same driver (or at least teh curren tPM6A) worked in a miniOnken.
Mr Drouin’s Low-Ken6
miniOnken/Fonken gallery pictures only (post #54)
dave
I was very surprised that that same driver (or at least teh curren tPM6A) worked in a miniOnken.
Mr Drouin’s Low-Ken6
miniOnken/Fonken gallery pictures only (post #54)
dave
I have those fantastic RA CG8T, with the doped cambric.
I originally bought some new from the factory, but they are easy to destroy.
I managed to repair some.
With the right enclosures, the right amp and some clever crossovers they are quite astonishing.
You see very few RA over here. I have had a few pair thru, and i have held onto this single in the hope i can help someone make a pair (or just needs a single). It could be a small 8 or a big 6, i’ll have to go measure it.
dave
dave
It's not R & A, it's RICHARD ALLAN! My original ones I bought from the factory in the 70s. Everyone has always said they sound really good. If you check carefully you would find the CG8/T had very large powerful magnets which the other 8" variants didn't. Having put the CG8 v the T variant side by side and compared, the CG8 was flat and uninteresting compared with the 8T, and the other 8" drivers they made weren't good either. In the end I was extremely lucky to get a pair of ancient sugden connoisseur vertical speakers which also had the RA drivers in. Once changed from the original "ordinary" 8" drivers to the 8T they make a really outstandingly good rear surround speaker, as it's a vertical bass reflex omni design.
Here is the interesting speaker. This goes back to early 60s & I have never seen another design like it.
Note the roll off of the mic and amp measurement system below 80hz.
The large spike at speaker resonance (77hz & 41hz ) is perfectly correctable with a DSP.
Note the roll off of the mic and amp measurement system below 80hz.
The large spike at speaker resonance (77hz & 41hz ) is perfectly correctable with a DSP.
Attachments
Seems reasonable since some of us use[d] a mechanic's stethoscope to search for 'hot spots' and/or to better 'map' a driver's overall tonal balance when getting serious about broadband tweaking.
+1 Bob Brines' passive frequency shaped MLTLs were a delight near-field out in a big room, but otherwise, 'much ado about nothing' to my ears as it really needs the compound horn it's basically designed for or at least frequency shaped OB + woofer system.
Much prefer the Urakoff overall, though sounds like they need to be level matched to be sure; ditto the #Goodmans#Feastrex#Urakoff comparison, though less is always less overall when comparing [radically] different size, efficiency drivers as the Urakoff again seems to have an unfair advantage overall.
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It was two years ago,but I will try to find this track.
One more comparison
Altec 755a VS Urakoff Oval Woodmonitors - YouTube
One more comparison
Altec 755a VS Urakoff Oval Woodmonitors - YouTube