Home |
Search |
Today's Posts |
#41
Posted to rec.audio.tubes
|
|||
|
|||
6DJ8 vs. 12AX7
Patrick Turner wrote:
However, its to be remembered that A or A' are negative if Vg is +ve. This would make the equation really for A' = -A / (1 + [ -A x ß ] ) This would not work out if the basic ohms law method I began with is viewed as the practical truth. So is ß really a -ve value? so that -A x -ß is a positive quantity because two -ve values are multiplied? This is all explained in excruciating detail in the Radiotron Designers Handbook the 1953 edition of which is readily available on the net. Ian |
#42
Posted to rec.audio.tubes
|
|||
|
|||
6DJ8 vs. 12AX7
Ian Bell wrote: Patrick Turner wrote: However, its to be remembered that A or A' are negative if Vg is +ve. This would make the equation really for A' = -A / (1 + [ -A x ß ] ) This would not work out if the basic ohms law method I began with is viewed as the practical truth. So is ß really a -ve value? so that -A x -ß is a positive quantity because two -ve values are multiplied? This is all explained in excruciating detail in the Radiotron Designers Handbook the 1953 edition of which is readily available on the net. Indeed, and it is excruciating. I just like formulas that just work simply, and where you don't have to worry about the signage in front of a gain or ß figure. Guess I just failed in my math exam eh. I have a paper folder which contains only formulas that work. All the others that didn't seem to work too good never made it into my folder. I must go through it one day and copy it out for the web; its the one very useful missing thing from my website, although there are a lot of formulas already there, all derived from RDH4, Wireless World articles, and extracts from other hard cover books in my little library of mostly old electronics from the 1950s. They were mostly chucked out in 1960 when solid state finally became reliable and cheap. Then the books seemed to stop being written, maybe ppl thought, "oh well, no use writing a book if its all going to become obsolete in 5 years." but a little later, things became obsolete in 18mths, and nobody wrote nuthin, and any little thing written was considered to be worth private money. I only have a very hazy idea of what signal flows occur in my PC.But I digress, again.... The math serves the understanding of the concept of FB and what it does, and provides quantified real answers. The FB does not exist so we can have exact mathematics, and beauty in mathematical expressions; the phenomena of simple motion were not created just to allow a nice set of math to be revealed by Newton. There is nearly always a perverse reason why we could say something exists. And there is no answer to why everything exists at all. Patrick Turner. Ian |
#43
Posted to rec.audio.tubes
|
|||
|
|||
6DJ8 vs. 12AX7
Patrick Turner wrote:
Ian Bell wrote: Patrick Turner wrote: However, its to be remembered that A or A' are negative if Vg is +ve. This would make the equation really for A' = -A / (1 + [ -A x ß ] ) This would not work out if the basic ohms law method I began with is viewed as the practical truth. So is ß really a -ve value? so that -A x -ß is a positive quantity because two -ve values are multiplied? This is all explained in excruciating detail in the Radiotron Designers Handbook the 1953 edition of which is readily available on the net. Indeed, and it is excruciating. I just like formulas that just work simply, and where you don't have to worry about the signage in front of a gain or ß figure. Guess I just failed in my math exam eh. I have a paper folder which contains only formulas that work. All the others that didn't seem to work too good never made it into my folder. I must go through it one day and copy it out for the web; its the one very useful missing thing from my website, although there are a lot of formulas already there, Seems to me all the really useful ones are there already. Ian |
#44
Posted to rec.audio.tubes
|
|||
|
|||
6DJ8 vs. 12AX7, ESL concerns.
Ian Bell wrote: Patrick Turner wrote: Ian Bell wrote: Patrick Turner wrote: However, its to be remembered that A or A' are negative if Vg is +ve. This would make the equation really for A' = -A / (1 + [ -A x ß ] ) This would not work out if the basic ohms law method I began with is viewed as the practical truth. So is ß really a -ve value? so that -A x -ß is a positive quantity because two -ve values are multiplied? This is all explained in excruciating detail in the Radiotron Designers Handbook the 1953 edition of which is readily available on the net. Indeed, and it is excruciating. I just like formulas that just work simply, and where you don't have to worry about the signage in front of a gain or ß figure. Guess I just failed in my math exam eh. I have a paper folder which contains only formulas that work. All the others that didn't seem to work too good never made it into my folder. I must go through it one day and copy it out for the web; its the one very useful missing thing from my website, although there are a lot of formulas already there, Seems to me all the really useful ones are there already. Yeah, but there is so much to know if you want to know ALL the reasons for why we do things in amplifiers and analog circuits. The message is a bit jumbled at my site, and there is no well linked index. I should really collate and co-ordinate the material better, and make room for the formulas that are not there. There are many concepts to grasp, well, i found I kept getting stuck as i went along, and continue to do so all the damn time. A guy here has got me building a kit for a pair of ESLIIIB speakers from http://www.eraudio.com.au/index.html Its slowly working out OK, but because there isn't any response data or impedance graphs at the ERA site, I am left wondering what the outcome will be, so I am furiously testing and calculating and creating alternative input circuitry and transformer design to make the speaker as benign to drive as Quad ESL57 or ESL63. I built the tube amps that will be used with these speakers, so the effort must have a good outcome. I have to say, anyone who does arrive with an ESL design as easy to drive as the Quad models really knows his stuff; there must be a very careful juggling of capacitance values, voltage ratios in trannies, and the tranny shunt capacitances. Most ppl tend to make the panel C high, and not worry about the shunt C of their step up transformers whose behaviour remains a mystery to most of them. Proof of the pudding is in the eating, and maybe by a week or two I will know what the optimum way to set them up really is. Some other ESL sites I found of interest are at http://www.ele.tut.fi/~artoko/audio/...ansformer.html http://www.justrealmusic.com/content/transformers.htm http://www.amplimo.nl/index.html?lan...arget=d36.html For those really wanting a challege to their powers of deduction, try reading the original notes about the design of Quad ESL57 by Peter Baxandall. Peter says what really needs to be said, a true electronic intellectual, who luckily was able to convey concepts fluently to anyone rather well, and the guys behind the URLs above are not quite up there yet. I'm struggling. Patrick Turner. Ian |
#45
Posted to rec.audio.tubes
|
|||
|
|||
6DJ8 vs. 12AX7, ESL concerns.
Patrick Turner wrote:
Yeah, but there is so much to know if you want to know ALL the reasons for why we do things in amplifiers and analog circuits. The message is a bit jumbled at my site, and there is no well linked index. I should really collate and co-ordinate the material better, and make room for the formulas that are not there. There are many concepts to grasp, well, i found I kept getting stuck as i went along, and continue to do so all the damn time. How about organising things along the lines of what you need to know at each stage of the design. So start with required input and output levels and impedances, bandwidth and distortion for example. Begin say with a simple line amp and show how to translate these into valve, topology and component selections. Then extend to harder designs like RIAA, mic pre and 600 transformer balanced outputs. A guy here has got me building a kit for a pair of ESLIIIB speakers from http://www.eraudio.com.au/index.html Its slowly working out OK, but because there isn't any response data or impedance graphs at the ERA site, I am left wondering what the outcome will be, so I am furiously testing and calculating and creating alternative input circuitry and transformer design to make the speaker as benign to drive as Quad ESL57 or ESL63. I have a couple of 10 inch Tannoy monitor Golds in very old original Tannoy infinite baffle cabinets. I love the clarity of the dual concentric design but the cabinets are boomy and lacking in extreme bass. I would love to build a pair of good sounding cabinets for them. I have seen complex horn designs that are way beyond my modest woodworking skills and tools. I was wondering if one of you cabinet designs could be tweaked for a single 10inch driver? Ian |
#46
Posted to rec.audio.tubes
|
|||
|
|||
6DJ8 vs. 12AX7, ESL concerns.
Ian Bell wrote: Patrick Turner wrote: Yeah, but there is so much to know if you want to know ALL the reasons for why we do things in amplifiers and analog circuits. The message is a bit jumbled at my site, and there is no well linked index. I should really collate and co-ordinate the material better, and make room for the formulas that are not there. There are many concepts to grasp, well, i found I kept getting stuck as i went along, and continue to do so all the damn time. How about organising things along the lines of what you need to know at each stage of the design. So start with required input and output levels and impedances, bandwidth and distortion for example. Begin say with a simple line amp and show how to translate these into valve, topology and component selections. Then extend to harder designs like RIAA, mic pre and 600 transformer balanced outputs. I don't have time for perfection. Who pays me for the time it takes to reach a more perfect state? There is a an answer for everyone for 99% of their queries at my website IF THEY TAKE THE TROUBLE TO LOOK FOR IT. It was easier for me to explain the priciples, give a few examples, and then leave everyone to do what they want by applying the principles. Life is all about applying principles to live, work, or play. I didn't set out to spend triple the time I did spend to make it easier than I have. I HATE spoon feeding 50 year old guys who cannot learn to think for themselves, or who have forgotten to question and answer the questions themselves. A guy here has got me building a kit for a pair of ESLIIIB speakers from http://www.eraudio.com.au/index.html Its slowly working out OK, but because there isn't any response data or impedance graphs at the ERA site, I am left wondering what the outcome will be, so I am furiously testing and calculating and creating alternative input circuitry and transformer design to make the speaker as benign to drive as Quad ESL57 or ESL63. I have a couple of 10 inch Tannoy monitor Golds in very old original Tannoy infinite baffle cabinets. I love the clarity of the dual concentric design but the cabinets are boomy and lacking in extreme bass. I would love to build a pair of good sounding cabinets for them. I have seen complex horn designs that are way beyond my modest woodworking skills and tools. I was wondering if one of you cabinet designs could be tweaked for a single 10inch driver? For good bass you have to build good cabinets. I don't like infinite baffles, or closed boxes. Usually speakers which are unported are said to be 'fast' and have good transients but usually if the box has no port, the makers didn't want to make the box big enough, nor want to go to the expense of boring one hole, and all thet say about closed box is BS and simply means there isn't much low bass. Its unusual you say infinite cabs are boomy, usually ported boxes get blamed for that and its because the speaker is too big bor its ported box, and a 6db peak at say 80Hz occus before an 18dB/octave roll off. I am nearly always happy if the box = VAS for the driver which usually means a box 2 or 3 times the volume that it came in from the makers, who like to use BS to happy ppl up, rather than supply the wood required. I can also measure a driver's TS parameters using formulas from David Weems and a standard test cabinet. Then I use WinISD , a box program for the volume and port details. Its all a lot of work, and you must be practical, and energetic about it or else nothing happens. Patrick Turner. Ian |
#47
Posted to rec.audio.tubes
|
|||
|
|||
6DJ8 vs. 12AX7, ESL concerns.
Patrick Turner wrote:
Ian Bell wrote: Patrick Turner wrote: Yeah, but there is so much to know if you want to know ALL the reasons for why we do things in amplifiers and analog circuits. The message is a bit jumbled at my site, and there is no well linked index. I should really collate and co-ordinate the material better, and make room for the formulas that are not there. There are many concepts to grasp, well, i found I kept getting stuck as i went along, and continue to do so all the damn time. How about organising things along the lines of what you need to know at each stage of the design. So start with required input and output levels and impedances, bandwidth and distortion for example. Begin say with a simple line amp and show how to translate these into valve, topology and component selections. Then extend to harder designs like RIAA, mic pre and 600 transformer balanced outputs. I don't have time for perfection. Who pays me for the time it takes to reach a more perfect state? Noone. You do it out of the goodness of your heart. There is a an answer for everyone for 99% of their queries at my website IF THEY TAKE THE TROUBLE TO LOOK FOR IT. I agree. It was YOU who suggested reorganising/updating it. Ian |
Reply |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
FS here before eBay... rare tube amps, NOS tubes; RCA 7591a, Amperex 6DJ8, RCA 5682, etc etc. | Marketplace | |||
FS here before eBay... rare tube amps, NOS tubes; RCA 7591a, Amperex 6DJ8, RCA 5682, etc etc. | Vacuum Tubes | |||
FA: Great Selection Of ECC83 12AX7 Preamp Tubes | Marketplace | |||
FA: 6SN7W, 12AX7, 12AU7, 6DJ8, 6L6G and Other Matched Pairs - Telefunken,Amperex, etc. | Vacuum Tubes | |||
E88CC / ECC88 / 6922 / 6DJ8 | Vacuum Tubes |