| flg |
An L Loaded ZV9, Why Not :D I just have this thing (DIY Thing) about not doing it exactly like N.P. does his thing. I like the L Loaded idea. Not to take away from Carpenter and his lead on ZV7-T and such, He seems to be taking it on and propagating that idea, etc... But, I really like the "idea" of the power JFET and the inductor loading. Very "Tube Like" :bigeyes: and such. I just figured that last year, I was working on an LH (PLH) and the Christmas music was fine... But it didn't work out as good as I would have hoped??? I need to get another proto working for Christmas music this year??? Why Not???
So, to that end, I'm putting together a ZV9 Gain stage on a big heatsink. I'll post a pic when I figure out I how I did that last. But, Just an LU1014D, with 2 IRFP240's cascoding it, and the load 1/2 above it. I would eventually want that to be a big L thing. And, I have a few. But, I might start with a light bulb or two, ala ZV8, but, waht do ya think???
Thanks... Gotta go cook for the parental units... |
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| carpenter |
| quote: | | Gotta go cook for the parental units... |
Boy, I've never heard it put that way before, uhh, you were talking about doing the "wild-thing" weren't you?:D :D :D
I love the sound of my choke loaded amp. I'm happy to see I have company. This will be an interesting thread.
John:)
Oh, I didn't notice the word "for". Kind of changes everything;) |
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| flg |
Wild Thing :bigeyes: No, I think that was a line from a Cone Heads movie :D :D :D
Can't seem to figure out how I get these schemo's into a usable format. Some application has taken over or something??? |
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| flg |
| O.K. something like this :smash: |
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| carpenter |
but you've got that little jfet supplying current to two mosfets:hot:
I'm thinking something along these lines (ground reference missing): |
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| carpenter |
| The inputs will need a ground reference. But, if you want to play with the source resistors: |
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| flg |
carpenter, are you trying to confuse me :confused: There will be a real small amount of current necessary for the gate to feel like it's GND'ed. It will get it through the feedback R and the 100 ohm to GND, just like the pics you posted(47 ohms). And, speaking of the pics you posted :confused: This is an SE amp not a big diff SOZ like your having fun with ;)
It is something between ZV8 with an Inductor & ZV9 - the Aleph. I'd like to try to get a little more Iq out of it than ZV9, and a little more linearity and effeciency than ZV8. The 2 cascode transistors are due to an eventuall expectation of close to a 37 Volt rail once things seem to work O.K.
So what's that 1000uF doin in there :confused:
FaLaLaLaLaa LaLa La La :D |
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| carpenter |
Can I blame it on my medication?:D
John:) |
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| carpenter |
| quote: | | There will be a real small amount of current necessary for the gate to feel like it's GND'ed. It will get it through the feedback R and the 100 ohm to GND, just like the pics you posted(47 ohms). |
I'm so glad to read this. I think it means that I don't need the extra resistor to ground at the gates of my buffers in my ZV7-T?
Thanks for the enlightenment!:D
John
btw, that big ol' cap is me copying Nelson's F1 (or was it the F2?) |
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| flg |
| I believe in ZV8 & 9, Nelson uses a gate to GND R in the circuits without feedback. Then when he adds feedback he takes them out... |
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| Nelson Pass |
| quote: | Originally posted by flg
I believe in ZV8 & 9, Nelson uses a gate to GND R in the circuits without feedback. Then when he adds feedback he takes them out... |
They are still there because the output is attached to ground
via resistance, and so a ground reference is still there through
the feedback resistor
:cool: |
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| carpenter |
So, could it be that the warm humming sound I heard when adding a 221K to ground at the buffer gate of my ZV7 was a ground loop hum? Did I attach the buffer correctly?
John:)
ooh, sorry for hijacking your thread, flg:xeye: |
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| flg |
Hi jack away dude. I wish I had a good answer for your ZV7-T with a buffer. The reason I don't is cuase I thought about that already a few months ago in the GSOZ-T thread I started and it becomes difficult to use feedback with the output at an absolute value of 23V or somethinig... You are then not really using the ZV4 buffer in the spirit it was originally used?
If I wasn't so busy with the "parental units" and my own ZEN variant, I might have some answers or ideas...
In your case, you have a voltage divider to ground from the output, in addition to the feedback requirement. A cap in the feedback line might be an answer but, that could also be a problem??? I need a cap in my output also but, a really big one... Gotta go for now... |
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| carpenter |
I solved the problem. At least, I think I did. I'll post a little schematic on my little ZV7-T thread describing pictorially what transpired.
Long story short, I doubled the resistor value from the output. It was 221k, now it's 442K. What a difference! I could actually turn down the gain knob on my electronic X-over. Happy days!
Thanks for thinking of me, flg.
John:) |
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| flg |
Well, it works :D :D :D I lit up my prototype ZV9 with an inductor load tonight :smash: Worked great! I'll post a pic of what I built with the exact values below. Except for the inductor. I really have no idea what it is:confused: Well, I have some idea I suppose. It's just that from all the reading I've been doing, and experimentation by others, and myself, I just figured what the hey, I'll just use the biggest thing I got up here. Especially if I have two of 'em. The inductor is actually an AC power Xfmr for 115VAC 60Hz input. Gotta weigh in at a good 15-20 lbs. The laminated core is 3" W x 4.5" H x 5.25" L. The secondaries are open. The Rdc measured about .2 ohms and it dosent even get warm at 2.5 Amps...
Some initial voltage measurements are on the pic. In addition, the -3db on the low end is about 10Hz! And, it's nice and flat up to at least 10K. It's starting to clip(on the positive side) at about 13.5 Vrms into my 7.5 ohm load resistor.
:D :D :D |
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| carpenter |
Great Scott! What does it sound like?
John:D |
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| flg |
| Sound :confused: Haven't tried anything like that yet... After a little more bench test I suppose I will. I don't really have any speakers worthy of critical listening at the moment though. That would be the next project :smash: :smash: :smash: |
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| flg |
I just had to try another Load. I plugged in an Avel 800VA Toriod in the 115V connection. I guess that would be rated at about 7 Amps rms. I believe I previously measured this thing at about 275mH of inductance :bigeyes: I was still running the Iq at 2-2.5A.
So :smash: it did not look as good :confused: Square waves seem to tell some kinda story here... The square waves have an overshoot worse than the laminated xfmr :confused: or at least at the same freq. This response seems to worsen at lower frquencies compared to the laminated guy. The -3db seemed to be more like 80Hz with much more extreme peaks on the rising edges... Hmmmm... Saturation :confused:
The high frequency response seemed to maintain a better looking square wave higher though. Also the -3db at the high end seemed to be more like 100KHz.
Now it would be interesting to try an air core device... Hmmm
:smash: :smash: :smash: |
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| Babowana |
| quote: | Originally posted by flg
The square waves have an overshoot worse than the laminated xfmr
|
It says, "Large overshoots are indicative of peaking or excess phase shifts in the high frequency response of the device under test."
And, "Well-behaved devices will have smooth overshoot, symmetrical on both positive and negative peaks."
:) |
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| Fuling |
| Toroids (usually) have no airgap in the core, so they tend to saturate very quickly in a situation where DC flows through the windings. |
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| flg |
Babowana, in both Ls, the square waves only "overshoot" at the low freqs. The rising edges begin to get rounded at higher freqs. The "overshoot" and rounding, does look realatively symetrical...
Also, I do not have the feedback resistor bypassed with the 10p C as Nelson sugests in ZV9 (it should make the square with look better). I beleive this will only help the high end though and in the opposite way??? I can try a C though. I also think varying the gain/feedback might be worth a try :smash: :smash: :smash:
Fuling, That 800VA Toriod is the biggest thing I have in Toriod... I tried lowering the Iq a little (25%) when I saw that but I saw little difference :confused: |
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| Babowana |
I would increase the 470uF to the greater than 1000uF
Anyhow, very good :) |
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| carpenter |
I think you'd be much happier with an air-core choke. I sure am. To keep the resistance down, I use my amp in the mids and up. This allows me to use a smaller choke.
I'm going to put my amp under the scope today.
I'd like to know more about PC based analyzing software.
You're having fun and sharing an excellent tail with the rest of us. That's what I call priceless.
John:) |
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| flg |
So John, I guess your weather is clearing up out there? Perfect DIY weather though Ha???
Yes, I guess I'm having fun...
At lunch I think I figured out some of my problem, I think...
In all my excitement to bench test, I don't have some of my typical stuff on this amp. I'm powering it with my 'ol standby rack mount switcher. Well I generally have 5-10mF of C on my boards right near the output transistors and I don't have a board for this one... So, I figured out while at lunch, I am probably seeing the transient response of my 'ol standby switcher supply in the output response of the amp??? I was a little hesitant to call it "overshoot" cause it's not quite overshoot looking and it just transfers from overshoot to rounding of the leading edges of the squarewave across the frq band???
I can look at the supply line first(shame on me) or, I'm going to hang a big cap or two on the switcher output, with a film or two, and see what the output looks like then??? I'll bet it gets right back in line with what it should look like...:D
First I gotta take Mom and go visit dad in the Hospital... Congestive heart failure and emphasema...
Ho Ho Ho Buddy:whazzat:
I'll get back to ya on the PC based Audio Anal Software:D |
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| flg |
| Babowana, Yep, I thought about that too:D And, that C kepps the amp on a real slow turn on too. But that power supply thing sounds more likely an important thing to correct first... I really have no idea what that supplies out Z, or transient response is:smash: :smash: :smash: |
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| flg |
Well, I doubled up on the cascode refrence bypass (2 x 470uF) and I added a 22,000 with a film to the choke input :confused: :confused: :confused: No change in the square wave response :confused: :confused: :confused:
Actually, the waveform is not exactly symetrical??? See below???
I can look around "the playroom" a little more for another xfmr... Or, I have a Lincoln arc welder transformer in the basement???
I can also switch to a resistive load and see what happens with that
:smash: :smash: :smash: |
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| carpenter |
| Resistive load; good thinking. |
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| Fuling |
| I think the best inductor in this circuit would be an iron cored one with airgapped core. Hammond has a few that would work, I´d go for >150mH. |
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| flg |
Yes, Hammond had some with High DC current specs. They are $50+US though. Do you have a specific part number? Are we thinking about the same type???
:smash: :smash: :smash: |
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| Fuling |
I don´t remember the part numbers, but I know there are one or two in the 193-series that should be suitable for this kind of job.
I´ve messed around a bit with inductor loaded amps and it´s a great way to get serious power out of single ended circuits. |
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| carpenter |
Hi Fuling,
Do you know if it's possible to get the Hammond choke in a center-tapped configuration?
John:) |
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| flg |
Carpenter, You asked about PC based analysis Software. Well, I really can't tell you much but, first, you need a good sound card. I like mine but I haven't used half the apps that came with it or had the need for the excellent specs yet. But, it is a Creative Professional E-MU 1212m digital Audio System, in PCI(takes 2 slots). It's 2 Ch with 192kHz sampleing. It has 32 bit internal processing and mixing etc. with expandable capabilitiers for those who have to have a studio in their putor. It is 2 ch balanced input and ouitput with profesional level(+4dbm) or consumer level-(-10dbV) and 120 db S/N. A THD spec of .000Something etc... Kick A for a couple $100:D
Then you go google(I like http://www.dogpile.com/) Audio analysis software, and I have a True RTA package and the Right Mark Audio Analyser 5.5. One of them was free, the other I paid for. These things have oscilators, rms voltmeters, spectrum analysers, scopes, etc. etc. Built right into your putor:D :D :D go do some searchining here and in dogpile and read up a little:smash: :smash: :smash:
I'll have mine going in a coouple days I hope, I'll let you know more then...:D Ho Ho Ho |
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| Fuling |
| Carpenter: I have no idea, perhaps you can ask them to custom wind a pair? Might be expensive though. |
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| Babowana |
| quote: | Originally posted by flg
Actually, the waveform
|
It is not an overshoot, but a "tilt"
I believe it is happening in LF, e.g. around 50Hz
I would not worry about at all, and be happy
Enjoy :) |
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| flg |
Babowana, I know what your saying, I was hesitant to call it "overshoot" too :D But it is following the frequency and reducing it's "delay" or saturation or whatever unitl a few kHz and then it starts becoming a rounded rising edge all the way up to rolloff. The falling edge maintains a reasonable shape until it becomes the -rising edge??? What do you make of the capacitor looking curve at the top(positive) portion of the curve but a straiter looking ramp on the negative side???
I can take a few shots in the dark, the "shotgun" method??? I'm going to change the output E cap to a bigger low ESR type. The one that's in there is scavanged from an old peice of equipment??? Also I might try some damping??? A 100 ohm across the choke or to GND???
I'm sure after I've floundered around a little, N.P. will send a few of his words of wisdom this way (Pls. Nelson). I have a few places to look for idea's first... And then, I have these 2, 27.4 ohm(13.7 in ll) 75W R's I can plug in to verify the basic amp topology without all the L is good...
:smash: :smash: :smash:
Oh,,, BTW Fuling, That was the 195T5 or the 195T10 Hammond unit I was looking at $$$:D http://www.hammondmfg.com/195.htm
John, I havent seen any center taped units??? But, can you do the square wave thing with your system and see it on the scope??? |
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| carpenter |
Unfortunately, I don't have a square wave generator; the old heathkit beast died in its sleep. I had to download a 1K soundwave file from iTunes. It did the trick.
Oh, did it ever:
Now for the bad news: my electronic x-over doesn't have symmetrical outputs; the negative side is one-third the voltage of the hot lead. Darn. It has a direct impact on my ZV7--and to think it still sounds so good.
If TDM can't correct the problem, I may be in the market for a DIY electronic x-over. Come to think of it, I'm going to build one anyway.
And if that weren't bad enough, the Aphex single-ended in/balanced out unit is not so balanced. There is no negative lead at all! I wrote them a seriously direct note with regards to false advertising.
Now, I'm also in the market to build a phase splitter.
Ahhhh, so many projects...:D
John:) |
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| flg |
Well John, I had my share of ignorance and stuff too. I've had my scope on the AC setting all this time and it really dosen't like a low freq square wave so much... Still getting used to it. I hooked up 13.7 ohms of resistor load and cranked the supply up to about 55V and set the scope on the DC settling and it does alot better... But there is still the slightest bit of this tilt still there??? And, the high freq rounding is still there... 10K dosent look so good :confused:
So :confused: :confused: :confused:
Back to the L's I guess:smash: :smash: :smash:
Did you measure your x-over connected to your ZV7? Maybe you should try unloaded or thru a known, or resistive load. You've been debuging and modifying alot with the ZV7 and maybe it is pulling something down??? |
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| flg |
After a little thinking and re-reading the ZV7 article, it is just likely that I should expect the performance my ZV9-L is getting???
Nelson experienced low frequency "saturation" characteristics even though ZV7-T cancels the DC field in the inductor. My prototype dose not. And, I have not done THD measurements that may be somewhat comparable to his graphs. I have only wittnessed the squarewave performance, however revelavent... When I loaded my prototype with 13.7 ohms of R, I saw good low frequency results.
Nelson had good mid-band performance. I actually seem to also. The squarewave looks the best from 1-5kHz.
Nelson also experienced higher freq distortion with his L loaded experiment. Well, althought I called it rounding of the squarewave, it is higher frequency distortion:bigeyes:
But with the R load, why do I still have high freq rounding of the leading edge of the squarewave:confused: :confused: :confused:
:smash: :smash: :smash: |
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| Babowana |
As far as I understand,
the rounding edge is due to the internal capacitance
The rounding indicates that the frequency is approaching
to the critical frequency, which might be 100kHz or above
And, we could use the rounding edge to estimate
the upper critical frequency, by reading the rise time |
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| flg |
Babowana, so would you expect it to sharpen up a bit if I were to lower my input and feedback Rs? I'm thinking maybe if I get the feedback R lower, the capacitance effects should shift higher in freq???
:smash: |
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| Babowana |
Hi, flg
I don't know well.
If the amp is an equivalent as one unit, it forms one set, or another,
of internal resistance and capacitance (and inductance?), which makes
the square wave of "tilt" at low frequency and "rounding edge"
at high frequency. I don't know how to calc the R and C values.
The lowering feedback resistor might affect the internal resistance.
Why not try to have an experiment?
Will be informative for the thread readers, too
:) |
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| carpenter |
| Substitute the valve for a transistor. In order to get the choke to cancel the DC and keep the AC, you could, perhaps, consider this: |
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| carpenter |
I had mentioned using a center tapped choke in this configuration on my ZV7 thread the other day.
Little did I know, someone had beat me to it.:D
You would take your voltage from the drain and source pins when substituting an FET for the valve.
Just for kicks, I might try this experiment tomorrow. I have a Plitron 1000 V/A tranny and a whole stack of FETs quaking in the corner.:bigeyes: :whazzat:
Someone smell smoke?:) |
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| carpenter |
| I'll try this out tomorrow: |
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| Fuling |
| Carpenter: That topology requires an airgapped inductor to work. |
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| Zen Mod |
| quote: | Originally posted by Fuling
Carpenter: That topology requires an airgapped inductor to work. |
topology shown with tube doesn't require gap, ordinary PP choke or xformer can be used,just because canceling effect of two current circs.
anyway,do you need AC feedback in cathode circ,that is another issue.
big cap can be handy there |
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| Fuling |
This topology is commonly refered to as "split load" in the tube world, and the inductor does indeed require an airgap.
I might be wrong, but I´ve read a lot of discussions on this exact topic and they all come to the conclusion that the inductor must have an airgap.
You can of course cancel the DC by connecting one of the windings out of phase, but that would also cancel the signal. |
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| Zen Mod |
| quote: | Originally posted by Fuling
This topology is commonly refered to as "split load" in the tube world, and the inductor does indeed require an airgap.
I might be wrong, but I´ve read a lot of discussions on this exact topic and they all come to the conclusion that the inductor must have an airgap.
You can of course cancel the DC by connecting one of the windings out of phase, but that would also cancel the signal. |
sorry fuling,I didn't clicked on little pic (to wiev it in another window) and I just presumed that winding are in cancelling arrangement (and .yes I know Iron Concertina) ......so -I just presumed that sorta McIntosh circ was drawed
besides that mistake,I commented just toob variant
what you sayed - worths for both pics sent by carpenter.
gap is a must |
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| flg |
I have lowered the input and feedback resistors in my ZV9-L and the results were as expected. I had a 10K input and a 75K feedback resistor. I kept the same ratio but, I went with a 5K input and a 37.5K feedback R. The10kHz squarewave looks pretty good now. The -3db on the upper end pushed up to about 136kHz:D :D :D
There did not seem to be any apparent affect with the inductors ability to maintain "square" waves at the low end. Still trying to work out what to do there :confused: :confused: :confused: I have plentty of air but can't afford many hundred feet of magnet wire right now:whazzat:
Everything seems to be quite stable otherwise... It's probably about time to plug in a speaker:D |
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| carpenter |
| quote: | | You can of course cancel the DC by connecting one of the windings out of phase, but that would also cancel the signal. |
I was trying to figure out how to cancel the dc saturation by connecting out of phase; apparently I didn't draw it correctly. I do this on my ZV7, how come the AC cancels out with this?
Thanks for the comments, fellows,
John:)
Excellent work, flg. I have to rush out but will study your post in an effort to learn. Thanks. |
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| Fuling |
If your ZV7 is built as shown in Nelsons article it´s a balanced design, right? (us tube guys would definitely call it push pull).
Having two active devices working in balanced mode with a centretapped inductor is entirely different from having one active device working in SE mode even if the inductor is split between the drain and the source. |
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| flg |
Yes, that's right Fuling. Carpenter has it much easier with his design I would say. But, I'm really not convinced all my problem is DC useing up all the available flux density(or whatever I should call it) and bringing the signal closer to saturation. I'm going to play with higher inductance and more gain next, on the premise that all the calculations are based on sine wave conclusions. Maybe music isn't square waves either but if I can do a descent square wave, music should be easy. Even Jimi Hendrex music:D I can also increase my load R substantially to simulate the effects of really large inductors without actually using them. Remember that THD tests are only done with sign waves also. I have tried cutting my Iq in 1/2 and I did not see enough of a change(except for lower gain) :smash: :smash: :smash:
Have you been part of the Pathos thread and the Choke Loads for ZEN Amps thread??? Based on some of that info 100mH inductor should produce good sound into the low freq range... I think the units I've tryed are double or more, that inductance???
:smash: :smash: :smash: |
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| Babowana |
| quote: | Originally posted by flg
I have lowered the input and feedback resistors in my ZV9-L and the results were as expected. I had a 10K input and a 75K feedback resistor. I kept the same ratio but, I went with a 5K input and a 37.5K feedback R. The10kHz squarewave looks pretty good now. The -3db on the upper end pushed up to about 136kHz:D :D :D
|
Wow
Plzed with good news
Make budget for a supertweeter :D |
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| flg |
I've performed a few more tests on the ZV9-L idea which may intrerest a few others. I tried connecting my 800VA toriod as the load, previously tested in the 115V connection, in the 230V connection. My expectation was that I would see the effects of the >1H inductance (4X the 115V connection) improve the output wave shape or the saturation effects worsen. It appeared that the saturation effects worsened much more than the increase in induction helped.
I also disconnected the feedback to take a look at open loop gain etc. :D Open loop gain, at 1kHz, with Iq of about 2.2A and a 7.5 ohm output load with 1Vp-p input, seems to be about 20 with my best EI laminated inductor as the load, and just short of 15 with my 13.7 ohm R as a load resistor.
I was running a gain of about 7 (16db) and about 10db of feedback, if my guess is correct...
:smash: :smash: :smash: |
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| Babowana |
| quote: | Originally posted by flg
which may intrerest a few others
|
Few others are having real values
and they are VIPs
:D |
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| flg |
As I was just posting in the ZV7-T thread, I'm thinking of changing the design to something like this :smash: :smash: :smash:
Higer input Z, more gain, better high frequency response??? |
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| carpenter |
That buffer looks so familiar;) I ran 442K on the feedback resistor and 147K to ground at the buffer's gate. The only difference is the 1uF blocking cap I have on the input. I also biased the buffer up with a 571 ohm source resistor.
I notice you're using an electrolytic and non-polarized cap in the power filtering stage above the buffer's source resistor. What does the n-p do?
I'm still digesting the rest of your circuit. Pretty picture!
John:) |
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| carpenter |
another thing: you placed a resistor to ground at the buffer input prior to the 10K gate resistor, whereas I ran my 147K to ground after. Is there a difference? I also ran 221 ohms in place of your 10K.
I'm all eyes.:D
John |
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| flg |
Yes, I think the R to ground at the input is likely unecessary. There is a path to ground through the feedback R and 100 ohm. If you don't give a MOSFET gate a path to GND it will float around... The tinyest leakage current will pull it to a DC GND with that R, but as I said, it's got a path. Your amp has a high DC voltage at the output, not a exactly a DC path to GND...
The R before the 10K is actually forceing the 10K to be the major contributor to the input impeadance. If it were after the 10K, the input voltage would be 9/10ths of it's level and the ratio of the 10K and 100K(F.B.) would have to share that impeadance(and signal current) and it would effect gain. Your amp has a DC current from the output looking for GND and it is part of a voltage divider from the output to GND. Therfore it sets the gate voltage of the buffer and you probably should have it there. A few posts ago I mentioned that. All those Rs in that area have to be considered for gain and follower bias etc. I did not like messing with it when I was playing with that design. I don't have to mess with the DC from my output, it's after the output cap, no DC:D
The 221 ohm, well, I remember looking at your circuit once and seeing huge gain(due to the 221 ohm). I thought you figured that out though??? In my circuit the 100k(F.B.) divided by the 10K determines the overall gain. No other considerations of output DC are involved... and The preamp or whatever basically see's The 100K in paralell with the 10K for an input impeadance to the amp.
So, what does your current schematic look like:bigeyes: :bigeyes: :bigeyes: hey we should be in the other thread with this:D |
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| carpenter |
I'm having a lot of fun reading your posts. They're quite informative.:)
I have no immediate response, 'cause I'm chewing on the meat of the subject.:D
John |
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| flg |
| I'm not the best writer, or teacher. Most of what I tried to say can be found in the ZV4 article, or I guess the ZV9 article. :D |
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| carpenter |
| quote: | | I thought you figured that out though??? |
flg, when it comes to my ZV7, I'm flying by the seat of my pants. I don't really know much about gain, though I'm trying to learn. Your posts get to the heart of the matter, and do so in short order.
I just plug things in and see what happens. Both approaches work, and for a newbie, it can be a rather exciting ride.
I like the way you calculate gain by keeping the dc out of the front end. Hopefully, I got that right? Do you just divide 100k by 10k to get a gain of 10? I'd enjoy reading how you arrive at the proper mathematical conclusion.
I could put a cap in series with my 442K feedback resistor to eliminate DC and find another way to set the bias point on the buffer. Seems to me that babowana suggested this a long time ago. This approach could allow greater flexibility.
For the input impedance of my amp, do I use a product-over-sum approach with the 442k and the 147k resistor? If so, does the input impedance have anything to do with gain?
I don't mean to swamp you, just curious about these things? I'm reading 4 hours a day in my $1.42 Malvino book. Man, that guy's wonderful! I'm learning a lot.
I can't wait to read about your experiences with the buffer,
John:)
I do enjoy reading your posts! :o |
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| flg |
I think the gain calc is close enough. If you actually set up the gain to be huge, it will only end up has high as open loop. Which really isn't that high in either of our amps.
I have some things to go do right now... I'll get back to you. I wanted to see your amp Schez(in the ZV7-T thread) before I say much about yours though... |
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| carpenter |
Thanks.
There are a few changes since the last posted schematic in the ZV7-T thread--post #227: R13 = 571 ohms; R6 = 147K; C12 is gone. |
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| Babowana |
| quote: | Originally posted by carpenter
I'm reading 4 hours a day in my $1.42 Malvino book.
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Mine is Fifth Edition :cool: |
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| carpenter |
| So is mine; hardbound, no less!:D |
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| flg |
So, I believe I had a Malvino textbook in college... Graduated 1979... What edition would that be???
:xmastree: :xmastree: :xmastree: :xmastree: :xmastree: :xmastree:
Probably cost me $80!!! |
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| carpenter |
1979 is the year of the second edition. You probably had the 1973, first edition--considering that you graduated the year the second edition came out.
You can find these deals cheap on Amazon.com. Go to the used book section.
Mine is a "staff" book, and is in perfect condition. What a buy...
John:) |
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| flg |
A staff book??? Does that mean it has an enffection:confused: :confused: :confused:
No. I really don't want to see that book ever again:D I'm waiting for the "Nelson Pass's First Watt of the Audio Power Amp" Or whatever he call's his first book:D :D :D The last book I read regarding our hobby is the Doug Self, Audio Power Amplifier Design Handbook. It is good. But, I'm not sure your ready to dig out that sh**:confused: :confused: :confused: I honestly can;'t suck up all that stuff...I'll help you if you do... It's got alot of good points... He would be a more well known name if it was the end all. But he isn't... Basically we are chasing down Class A stuff and he isn't... I'd really like to see John Curl on this Forum more often... He's probably holding out for the Curl Forum:D :D :D
Anyway, for me and the interest of others, I should get some real THD and stuff numbers from what I have and some tweaks, as N.P. suggests, before I modify it to the dual JFET gain stage:smash: :smash: :smash: :xmastree: :xmastree: :xmastree: :xmastree: |
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| flg |
Well, where have we all been??? ZV7-T'ing it? Zen-9'ing it? F4'ing it? :D :D :D
No new responses or experimental results from the "Choke Loads for Zen-Aleph Amps" thread... :whazzat:
No new posts on the "Pathos Amplifiers" thread... :whazzat:
And, I guess I'm the one to try to bring this idea back to life :D
This is where I'm at: I recently recieved a couple Hammond 195T5 Chokes. I tested them in a single and dual JFET gain stage as previously described (1.7A & 3.4A idle current). I can report the curvature of the square wave is gone until down to about 25-30Hz. I guess that's the saturation area although idle current seemed to make very little if any difference... The tilt of the square wave "plateau" is still there somewhat below 100-200Hz??? I think that is the inductance value showing itself. I see a little ringing in the rising edge but that was running open loop. I'm going to aim for a gain of about 8 with 6db of global FB...
I'm currently in the process of collecting some additional components and laying out a PCB to make it nice and tidy. Not sure exactly how to do the chasis yet. Probably going the monoblock route though...
I'll include the latest ideas in a pic :D |
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| carpenter |
Interesting schematic, Lee. Is the 2SJ a smoother sounding fet than the P3310? I was wondering if it would be of benefit to switch the two; let the 3310 be the current source?
Have you given your idea a listen, or are you going for the pcb first?
Fun stuff to play with, I'm sure.
I'm having a ball with my ZV7-TJBC (jfet; buffered; cascoded). What a fine experience. I've received three pcbs from Express PCB and will construct a final prototype amplifier, soon. At this moment, I'm designing a pcb with ground-plane in a joint effort with Magura; more fun than any human should have... am I a lucky guy, or what?
One last thing; this regards candy stores: Apex Jr. is an excellent place to shop; great products at incredible prices! I just purchased four 200 v/a transformers with steel casings for $15.00 each. They work beautifully in the 20 volt version of my ZV7-TJBC. I also purchased two 1600 v/a transformers for $45.00 each for the larger amplifiers...uhhh, my electric bill went up $30.00 a month...ooops. (If I keep bragging Steve up, I'm going to have to charge an advertising fee...ha :D)
Keep us posted on your success, Lee. Your enthusiasm is a breath of fresh air.
John:) |
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