Overhere (and Thodio is overhere), that's a contemporary construction worker's stereo.
Military surplus stores are treasure caves, imo.
e.g. 55lb field toroidals, rebuilt four of them to floating isolation transformers : http://www.diyaudio.com/forums/atta...87426-pass-monster-separation-1600va.big4.jpg
TVRgeek, ferrofluid improves thermal handling and dampens the resonant peak. For manufacturers, this means they can use smaller voice coils and magnets for the same power handling, for designers, it means they have one thing less to worry about. The resonant peak is typically only 1-2 octaves from the xover frequency, so you have to deal with it. One way is to put a series resonant circuit over the tweeter. Another is, but this only works if the tweeter has a much higher efficiency than the driver below it, to put a resistor accross the tweeter, and one in series. This averages out the resonant peak to some extent, so that the crossover may do its work (or not).
So, if it is cheaper to produce ferrofluid tweeters, and if they are easier to work with, then why are they typically shunned in the higher end of the market, give or take a few exceptions?
The reason is that tweeters without ferrofluid to most ears sound better, more open, what have you, in a correct application. And the reason for that is that ferrofluid introduces friction, which, as I set out before, is never a good thing in a driver.
vac
Ferrofluid
I think I am right in saying the little cheap Audax used ferrofluid ( Looks like Mercedes badge and cost then less than $1 in quantity ) ? It was a formerless coil construction . It seemed to be a very advanced design which lent itself to cheaper production . If I an right it couldn't function without the fluid . Also I was told it reduced warranty claims as it transferred heat . I do remember some of my favorite speakers had ferrofluid tweeters . I also remember being told they were difficult to design around ( Spendor ) . I detested the titanium tweeters found in many British speakers that followed the Celestion SL6 copper tweeter ( 22kHz notch filter ) . Many abandoned cloth tweeters about then . I liked the Hicophon ( spelling ? ) . Many tweeters were originally microphone capsules ( STC 40001 G was I think AKG ) . Why not now ? .
I think I am right in saying the little cheap Audax used ferrofluid ( Looks like Mercedes badge and cost then less than $1 in quantity ) ? It was a formerless coil construction . It seemed to be a very advanced design which lent itself to cheaper production . If I an right it couldn't function without the fluid . Also I was told it reduced warranty claims as it transferred heat . I do remember some of my favorite speakers had ferrofluid tweeters . I also remember being told they were difficult to design around ( Spendor ) . I detested the titanium tweeters found in many British speakers that followed the Celestion SL6 copper tweeter ( 22kHz notch filter ) . Many abandoned cloth tweeters about then . I liked the Hicophon ( spelling ? ) . Many tweeters were originally microphone capsules ( STC 40001 G was I think AKG ) . Why not now ? .
Nope, scored the quadruple down south.
(up till a couple of years ago, i had a contact in Vlaardingen who delivered "pre-selected" items.
mostly valves and caps, very retired electronics guy, spent his time unpaid two days a week at Quakkelstein. wheeling & dealing is more up my alley)I honestly don't believe there's anything wrong with titanium dome tweeters as such, but exactly how well or not they have been made applies to them just as much as to everything else.
My speakers use Son Audax' best offering at the time (2003). For a start, they were not on a palstic, but on a hard metal base. Their magnet did not weigh like 100 grams, as many commercial units have, but 600 grams, which is quite a lot of magnet for what is supposed to be an ultra light dome. In my speakers, they kick in at 3.5 kHz, just above the midrange, which covers the range from 800 to 3,500 Hz. And they do not sound shrill or offensive in any way.
On the other hand, like most of us here, I have heard a lot of titanium domes which were plainly put junk. And their purchase price reflects it, many cost like €12...25, so what do you expect for peanut money? By comparison, mine cost (master dealer's price) €92.
What most Brits do not know, and when told do their best to disbelieve, is that the British loudspeaker industry actually used low end drivers in their rather expensive models until around 2003, when I stopped bothering to even look.
No I don't think there is anything wrong with titanium either . Celestion knew the problem they had created and fixed it ( I adore the SL6 ) . Ironically it helped with CD of the time to have that . I talked with Derek Hughes about the higher grade Audax tweeters used on the Spendor Prelude . He said that the Audax was not an easy drive unit ( low end resonance ) . The Spendor sounds very different to other using the same from competitors . The exception was a company called Stag who where furniture makers and used a standard Audax recommended crossover . They also were very good ( no success with sales ) .The Audax I refer to I feel had a boost from the use of ferrorfluid, it was not as nasty as it's low price suggested ( I tried it without and it was not as good , not intentionally ) . I love miracles of low price engineering and it was one . When I doubted ferrorfluid I was told it had a remarkable effect on the magnetic circuit , also is a lubricant and cooling substance . When I complained that it had friction I was told the partials are miniscule and that the cone excursions miniscule also . The general opinion was that it was good . The Celestion tweeter was made from copper because it could be made by electroplating and had fewer in built stress defects . I think that will sound better than punched domes . I heard some old large Altec paper tweeters . They were fantastic and were nothing like others of the same type . One of the best I ever heard was on Russian speakers which mimic Spendor BC1 . The tweeter looked like STC .
Well, as far as I am aware, the very first titanium dome was used by JBL in 1984, on their current at the time incarnation of their venerable 4312 monitor. And they do not use stamped domes, they use vapor deposition.
I agree on wonderful surprises of low cost enigineering. In the late 70ies, a friend bought a pair of Dual loudspeakers, I forgot their designation, but fairly large boxes, acoustic suspension, using a 12" paper bass, 4" (or so) paper midrange and a textile treated dome tweeter. Dual has always been best known for their turntables, certainly not speakers, but that model a true gem. It wasn't dirt cheap, but it was cheaper than most of its competitors at the time.
And it played some wonderful music. On price basis, it could take on any AR, KLH, Jensen, etc speaker from far better known companies and make mince meat out of them, because the competition's equvalent speakers used to cost like twice its price.
Sometimes, companies lose it and shoot themselves in the foot. Dual again - in the late 70ies, they put out model CS 604 of their TT. Direct drive, quartz locked, gimbal suspension of the arm, ultra low mass, etc, price very reasonable. It was their shortest lived model ever, because an odd thing happened. Reviewers and buffs discovered that if you used a decent cartridge, it delivered a sound say 2-3% worse than Dual's top turntable of the day (I think it was 721, but am not sure), which cost twice the price. So people literally created waiting lists for it, while the sales of the 721 plummeted. It went on sale sometime in May, I bought mine in August, and by the end of October, it was gone, replaced by model CS 606. This was a very, VERY plain (being kind here) TT which didn't merit a second look, but things were back to normal and Dual seems to have been happy.
On the other hand, fates are not always kind. Not many here will remember a long gone UK manufacturer of receivers named Armstrong. They produced a model in the late 70ies which I had an opportunity to audition. In design, it went along the Bang & Olufsen route, modern, up to date looks, but with typical British restraint. More to the point, the sound was better than almost any I had ever heard from a receiver, price notwithstanding, perhaps only a few top of the line Marantz receivers did as well or slightly better, the rest were way behind. And that's saying something, because at the time, Marantz was the King of The Receiver Roost, considered the best even if others had more power at hand.
This little Armstrong had around 40 wpc, nothing exorbitant, yet the sound QUALITY was truly outstanding. Obviously, if I still remember it fondly 35 years down the line.
Unfortunately, the company didn't last too long, about a year or two, tops, and then simply disappeared. A pity.
It happens, not often, but every now and then.
I agree on wonderful surprises of low cost enigineering. In the late 70ies, a friend bought a pair of Dual loudspeakers, I forgot their designation, but fairly large boxes, acoustic suspension, using a 12" paper bass, 4" (or so) paper midrange and a textile treated dome tweeter. Dual has always been best known for their turntables, certainly not speakers, but that model a true gem. It wasn't dirt cheap, but it was cheaper than most of its competitors at the time.
And it played some wonderful music. On price basis, it could take on any AR, KLH, Jensen, etc speaker from far better known companies and make mince meat out of them, because the competition's equvalent speakers used to cost like twice its price.
Sometimes, companies lose it and shoot themselves in the foot. Dual again - in the late 70ies, they put out model CS 604 of their TT. Direct drive, quartz locked, gimbal suspension of the arm, ultra low mass, etc, price very reasonable. It was their shortest lived model ever, because an odd thing happened. Reviewers and buffs discovered that if you used a decent cartridge, it delivered a sound say 2-3% worse than Dual's top turntable of the day (I think it was 721, but am not sure), which cost twice the price. So people literally created waiting lists for it, while the sales of the 721 plummeted. It went on sale sometime in May, I bought mine in August, and by the end of October, it was gone, replaced by model CS 606. This was a very, VERY plain (being kind here) TT which didn't merit a second look, but things were back to normal and Dual seems to have been happy.
On the other hand, fates are not always kind. Not many here will remember a long gone UK manufacturer of receivers named Armstrong. They produced a model in the late 70ies which I had an opportunity to audition. In design, it went along the Bang & Olufsen route, modern, up to date looks, but with typical British restraint. More to the point, the sound was better than almost any I had ever heard from a receiver, price notwithstanding, perhaps only a few top of the line Marantz receivers did as well or slightly better, the rest were way behind. And that's saying something, because at the time, Marantz was the King of The Receiver Roost, considered the best even if others had more power at hand.
This little Armstrong had around 40 wpc, nothing exorbitant, yet the sound QUALITY was truly outstanding. Obviously, if I still remember it fondly 35 years down the line.
Unfortunately, the company didn't last too long, about a year or two, tops, and then simply disappeared. A pity.
It happens, not often, but every now and then.
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Armstrong 625
Hi DVV . I use an Armstrong 625 everyday of my life . I bought my father a CS 510 at the same time as you speak of and admired the CS 704 . My acquaintance ( difficult to say my friend , my fault ) was Michael Gerzon . Michael found answers to these questions . If anyone wants to make a fortune read Michael's work . Anyone who wants to talk Ambiosonics is always welcome and sound-field mikes . It wont be technical .
http://www.audiosignal.co.uk/Resources/Why_do_equalisers_sound_different_A4.pdf
Hi DVV . I use an Armstrong 625 everyday of my life . I bought my father a CS 510 at the same time as you speak of and admired the CS 704 . My acquaintance ( difficult to say my friend , my fault ) was Michael Gerzon . Michael found answers to these questions . If anyone wants to make a fortune read Michael's work . Anyone who wants to talk Ambiosonics is always welcome and sound-field mikes . It wont be technical .
http://www.audiosignal.co.uk/Resources/Why_do_equalisers_sound_different_A4.pdf
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What can I say? Lucky you.
Have you refreshed it (changed the capacitors, readjusted) recently?
Samwa 4700 uF Audio grade . Armstrong 625
This is my little work horse and not for showing off usually . The bias is by fixed resistor . Note TV transistors for drivers and H C Lin style circuit . Armstong supplied dummy speaker loads for technical reviews to show how well it performed with IMD . Note it has a Toroidal transformer years before others ( Circa 1973 ) . The Radio side is sublime . My late brother did it up for me so it is very precious . The tape monitor circuit is A la Naim and no tone controls in circuit ( it sounds better ) . It has diode noise gate switching . Iscra resistors ?
This is my little work horse and not for showing off usually . The bias is by fixed resistor . Note TV transistors for drivers and H C Lin style circuit . Armstong supplied dummy speaker loads for technical reviews to show how well it performed with IMD . Note it has a Toroidal transformer years before others ( Circa 1973 ) . The Radio side is sublime . My late brother did it up for me so it is very precious . The tape monitor circuit is A la Naim and no tone controls in circuit ( it sounds better ) . It has diode noise gate switching . Iscra resistors ?
This is my little work horse and not for showing off usually . The bias is by fixed resistor . Note TV transistors for drivers and H C Lin style circuit . Armstong supplied dummy speaker loads for technical reviews to show how well it performed with IMD . Note it has a Toroidal transformer years before others ( Circa 1973 ) . The Radio side is sublime . My late brother did it up for me so it is very precious . The tape monitor circuit is A la Naim and no tone controls in circuit ( it sounds better ) . It has diode noise gate switching . Iscra resistors ?
Actually, some of those resistors in the lower right corner really do like they were made by Iskra (literal translation: Spark), one of ex-Yugoslavia's two large electronics companies. That one was from Slovenia. The other is Ei Niš, which is from Serbia.
As far as I am aware, a fair share of Californian tube audio manufacturers use Ei Niš tubes as we speak. They also make military electronic equipment, yet during the US/NATO bombing of 1999, they hit old people's homes, maternity wards, civillian trains and whatnot, claiming all of them to be "military targets", but not a single bomb ever fell on Ei Niš. You don't do things to endanger your own industry, even if it's not too big in absolute terms.
Thanks DVV .We got off of what we hear and what we measure . I think what we hear comes first . If not why do we do this ? I made an amp recently that measures great ( perfect by any sensible standards ) . I don't like it''s sound . However I have another that measures about the same and is wonderful . I know why but it still puzzles me . Both are Blameless . Transconductance problems are the cause , yet it's hard to prove . The distortion I see into the VAS is not a ghost I feel .
Nigel, go back a bit and you'll come across a debate, one I sort of started, then JC and Thorsten picked up, and it had a good life. Some ideas were flung around, perhaps not all workable, but at least stimulating to those who think.
Basically, Thorsten put forth the idea that what we measure is all fine and well, but the key point is not low figures, but rather how you got them. Wahab here favors most of the correction signal to come from the overall NFB, while Thorsten and I prefer more local and less overall feedback. A LOT less, say no more than 20 dB worst case, and peferably less. Using more global NFB will give better nominal THD, but more HF distortion, whereas less global and more local will give poorer overall figures, but much less HF distortion. That's the gist of it.
If by "blameless" you refer to Douglas Self's approach, then I must disappoint you. I am no fan of D.S., although I highly respect his willingness to sit down and write it all up. However, I feel his approach will yield a lot of very poor sounding amplifiers, with a few runaway exceptions here and there - just my view, no more, I don't do Great Universal Carved In Stone Truths. I'm not that big, just 6'3", 250 lbs.
Basically, Thorsten put forth the idea that what we measure is all fine and well, but the key point is not low figures, but rather how you got them. Wahab here favors most of the correction signal to come from the overall NFB, while Thorsten and I prefer more local and less overall feedback. A LOT less, say no more than 20 dB worst case, and peferably less. Using more global NFB will give better nominal THD, but more HF distortion, whereas less global and more local will give poorer overall figures, but much less HF distortion. That's the gist of it.
If by "blameless" you refer to Douglas Self's approach, then I must disappoint you. I am no fan of D.S., although I highly respect his willingness to sit down and write it all up. However, I feel his approach will yield a lot of very poor sounding amplifiers, with a few runaway exceptions here and there - just my view, no more, I don't do Great Universal Carved In Stone Truths. I'm not that big, just 6'3", 250 lbs.
@ JC,
Speaking Off, I have one of your Halo's coming in possibly next week genius,
recommended it to a good friend, we will see .....
Michael Gerzon :
After studying mathematics at Oxford University, Gerzon joined Oxford's Mathematical Institute working on axiomatic quantum theory, until his work in audio took him into working as a consultant. At university he already had a keen interest in both the theory and practice of recording, which he shared with a few fellow students including Peter Craven (the two were later the co-inventors of the soundfield microphone, and collaborated on many other projects).
Over the next few years, this interest led to the invention of Ambisonics, which can be seen as a theoretical and practical completion of the work done by Alan Blumlein in the field of stereophonic sound. Although Ambisonics was not a commercial success, its theory underpinned much of his later work in audio such as his work with Waves Audio and Trifield. He was also active in the development of digital sound techniques, such as noise-shaped dither and Meridian Lossless Packing (MLP, the lossless compression used in DVD-Audio disks).
The Audio Engineering Society recognised Gerzon's work in audio by awarding him a fellowship in 1978 and the AES Gold Medal in 1991. He was also awarded the AES Publications Award posthumously in 1999.
Speaking Off, I have one of your Halo's coming in possibly next week genius,
recommended it to a good friend, we will see ..... Michael Gerzon :
After studying mathematics at Oxford University, Gerzon joined Oxford's Mathematical Institute working on axiomatic quantum theory, until his work in audio took him into working as a consultant. At university he already had a keen interest in both the theory and practice of recording, which he shared with a few fellow students including Peter Craven (the two were later the co-inventors of the soundfield microphone, and collaborated on many other projects).
Over the next few years, this interest led to the invention of Ambisonics, which can be seen as a theoretical and practical completion of the work done by Alan Blumlein in the field of stereophonic sound. Although Ambisonics was not a commercial success, its theory underpinned much of his later work in audio such as his work with Waves Audio and Trifield. He was also active in the development of digital sound techniques, such as noise-shaped dither and Meridian Lossless Packing (MLP, the lossless compression used in DVD-Audio disks).
The Audio Engineering Society recognised Gerzon's work in audio by awarding him a fellowship in 1978 and the AES Gold Medal in 1991. He was also awarded the AES Publications Award posthumously in 1999.
Yes, I'm aware of the HD and IMD higher terms appearing with a little feedback, even local. I'm not sure I've yet seen convincing examples of the pervasive notion that global feedback gives rise to these high-order terms.
What I propose: two amplifiers, same nominal transfer function. As similar as possible but one with a lot of local and correspondingly less global FB. Suppose that all of the terms, HD and/or IMD, are very low.
Do we still have people who will hear the supposedly deleterious effects of the higher global feedback? I'm presuming that we don't violate with obvious problems like having insufficient slew rate.
dvv,
Hmmm. This could be key to what I am chasing. Getting less high order distortion while not crippling bandwidth like the Rotel does. In the mean time I am working on notch filters for the crossovers to hopefully make them less susceptible to the possible effects. Unfortunately, no answer yet from e-mu on why their drivers are crashing. I have gotten conformation I am not the only one who has had this problem.
On how, after increasing the size of degeneration resistors, not sure where to go from there. So much to learn. Parallel the MC cap with a resistor?
Hmmm. This could be key to what I am chasing. Getting less high order distortion while not crippling bandwidth like the Rotel does. In the mean time I am working on notch filters for the crossovers to hopefully make them less susceptible to the possible effects. Unfortunately, no answer yet from e-mu on why their drivers are crashing. I have gotten conformation I am not the only one who has had this problem.
On how, after increasing the size of degeneration resistors, not sure where to go from there. So much to learn. Parallel the MC cap with a resistor?
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