One common distortion source at large signal swings is the modulation of the FET input capacitance. It's a tribute to what you're doing right that this doesn't dominate.
Now what you need to do is go octal😉
Now what you need to do is go octal😉
My observations, ie posed as questions.. for whatever it's worth:
The boards, power supplies, voltages, etc in the tube section can probably handle the 'pressure' of being stressed, with minimal mods (specifically the PS) to handle octal tubes. In my limited understanding of what goes on, the circuits tend to be similar in layout and parts orientation. Ie, similar circuits, different values. It's the driving of the fets that is the more serious issue, no?
Now, is it possible to do a octal change to the SA-220? I don't mind building/burning and installing riser boards with a few extra parts located on them. Or are we (whatta ya mean we?...well I'm trying to get these puppies re-done!) talking getting rid of the fets altogether and going octal, due to the drive current required for BJT? Or are the 6922/6DJ8 good enough for the output section? Or, like the NYAL Moscode 600, go to 6FQ7? Or sell these pieces of whatever and move on to something else? Like what, I say? I think my best bet might be to fix these, no matter what the cost. I mean, what else is out there, to even begin with?
What I'm looking to know, is seriously, what are my chances of getting beyond the standard audiophile builder/wannabe insofar as ground level improivements in these. I'm not a designer, but I do know how to burn my own boards, iffin' I have to.
These are pertinent questions here guys. What is the status. Is there going to be a mod for these units, in any fashion whatsoever? If yes, what time frame and cost? or is this whole thing going to remain on ME's doorstep? I'm looking at my watch, and my wallet. I don't desire to do this twice, and I don't desire to be playing with modifying my design tools forever. I've got no time for that.
A subtle refinement on my earlier post concernig loudspeakers. The loudspeaker, as it stands, in the realm of design and execution, is part of the obervational chain or system, for designing or observing the effects of amplifier design.
Inescapable, it is. Joined at the hip. Now, if a loudspeaker comes along, that creates a better window, by far, then the ideas used, the emphasis of specific design points and their execution, etc,.....changes. Or the observational system or window is cleaner...thus..creating a different result, for in the end..the amplifier must sound like music. We are doing what we can to create neutral and dynamically correct speakers, while ensuring that the measurements are secondary to that point of design.
Chris: If you get some good tools to US, we'll get some good tools to YOU.
Sorry to pose the hard questions, but I gotta get this done and move on to other things. I don't mind if it takes months, but there has to be action and direction.
The boards, power supplies, voltages, etc in the tube section can probably handle the 'pressure' of being stressed, with minimal mods (specifically the PS) to handle octal tubes. In my limited understanding of what goes on, the circuits tend to be similar in layout and parts orientation. Ie, similar circuits, different values. It's the driving of the fets that is the more serious issue, no?
Now, is it possible to do a octal change to the SA-220? I don't mind building/burning and installing riser boards with a few extra parts located on them. Or are we (whatta ya mean we?...well I'm trying to get these puppies re-done!) talking getting rid of the fets altogether and going octal, due to the drive current required for BJT? Or are the 6922/6DJ8 good enough for the output section? Or, like the NYAL Moscode 600, go to 6FQ7? Or sell these pieces of whatever and move on to something else? Like what, I say? I think my best bet might be to fix these, no matter what the cost. I mean, what else is out there, to even begin with?
What I'm looking to know, is seriously, what are my chances of getting beyond the standard audiophile builder/wannabe insofar as ground level improivements in these. I'm not a designer, but I do know how to burn my own boards, iffin' I have to.
These are pertinent questions here guys. What is the status. Is there going to be a mod for these units, in any fashion whatsoever? If yes, what time frame and cost? or is this whole thing going to remain on ME's doorstep? I'm looking at my watch, and my wallet. I don't desire to do this twice, and I don't desire to be playing with modifying my design tools forever. I've got no time for that.
A subtle refinement on my earlier post concernig loudspeakers. The loudspeaker, as it stands, in the realm of design and execution, is part of the obervational chain or system, for designing or observing the effects of amplifier design.
Inescapable, it is. Joined at the hip. Now, if a loudspeaker comes along, that creates a better window, by far, then the ideas used, the emphasis of specific design points and their execution, etc,.....changes. Or the observational system or window is cleaner...thus..creating a different result, for in the end..the amplifier must sound like music. We are doing what we can to create neutral and dynamically correct speakers, while ensuring that the measurements are secondary to that point of design.
Chris: If you get some good tools to US, we'll get some good tools to YOU.
Sorry to pose the hard questions, but I gotta get this done and move on to other things. I don't mind if it takes months, but there has to be action and direction.
Hi SY,
I can't take the credit for that. I removed the output FETs and went bipolar. The gate charge characteristic, coupled with bias current control issues seemed to be more trouble than it was worth. The same exact circuit in the vas driving bipolars was a quantum leap forward in performance. Sonically much better. No problem picking this out in an A-B-X test!
I have a stock SA-100, vas modified SA-100 and an SA-100 vas modified with bipolar output. I like to see where I am compared to what was. Therefore, in the listening tests, we can always pull out the previous type to see where we are sonically.
It's gratifying to see bench test data agreeing with what is heard in listening tests. Good design practices always improve the listening experience I think.
Octal. That was one of my future plans (properly redesign the vas). The HV regulator stays for sure. I was going to try with 6SN7, 6SL7, 12AX7A and 6DJ8 (cause I got them). A 12AY7 approch may be interesting. I was going to load the plate of the output with a current source to keep the heater cathode differential sane.
Solid state. Also in my plans are a low gain fet input solid state vas. I feel a very linear amplifier can be created that sounds very "tube like". The Counterpoint is nothing more than a test bed at this stage.
-Chris
I can't take the credit for that. I removed the output FETs and went bipolar. The gate charge characteristic, coupled with bias current control issues seemed to be more trouble than it was worth. The same exact circuit in the vas driving bipolars was a quantum leap forward in performance. Sonically much better. No problem picking this out in an A-B-X test!
I have a stock SA-100, vas modified SA-100 and an SA-100 vas modified with bipolar output. I like to see where I am compared to what was. Therefore, in the listening tests, we can always pull out the previous type to see where we are sonically.
It's gratifying to see bench test data agreeing with what is heard in listening tests. Good design practices always improve the listening experience I think.
Octal. That was one of my future plans (properly redesign the vas). The HV regulator stays for sure. I was going to try with 6SN7, 6SL7, 12AX7A and 6DJ8 (cause I got them). A 12AY7 approch may be interesting. I was going to load the plate of the output with a current source to keep the heater cathode differential sane.
Solid state. Also in my plans are a low gain fet input solid state vas. I feel a very linear amplifier can be created that sounds very "tube like". The Counterpoint is nothing more than a test bed at this stage.
-Chris
Aha! Much better idea. I've never been happy with the linearity of power MOSFETs in output stages- or, I should say, the relative lack of linearity. I'd love to see a schematic if you feel comfortable sharing it.
Hi Ken,
I will be designing an improved amp for the SA-220. It will benefit from the development on the SA-100 directly. So we are in a design process for that right now. Therefore, the developmental cost will be much reduced compared to the SA-100. The SA-100, as it sits right now, really kills the SA-220 sound wise. There is nothing wrong with the case and heatsinks you have. The transformer will be fine if we stay with a tube version for the vas. Consider the output FETs history given what I have seen so far. And it will run cooler. My suggestion would be to modify one, or hear one that's done, and make your mind up then.
The mod will involve replacing all the boards, so it is reversable by reinstalling the old stuff. In the SA-100's right now, I remove the boards and modify them before reinstalling them. Three new PCB assy's are added.
So far, this has cost me for parts and time. I will set it up right before releasing these in the wild. That means you are not footing the bill for developement.
-Chris
I will be designing an improved amp for the SA-220. It will benefit from the development on the SA-100 directly. So we are in a design process for that right now. Therefore, the developmental cost will be much reduced compared to the SA-100. The SA-100, as it sits right now, really kills the SA-220 sound wise. There is nothing wrong with the case and heatsinks you have. The transformer will be fine if we stay with a tube version for the vas. Consider the output FETs history given what I have seen so far. And it will run cooler. My suggestion would be to modify one, or hear one that's done, and make your mind up then.
The mod will involve replacing all the boards, so it is reversable by reinstalling the old stuff. In the SA-100's right now, I remove the boards and modify them before reinstalling them. Three new PCB assy's are added.
So far, this has cost me for parts and time. I will set it up right before releasing these in the wild. That means you are not footing the bill for developement.
-Chris
ok. give me a call, ad relay the time frame, etc. I'm ready to get this going, iffin' you have the time. I'd give (ship) you both units tomorrow, if nesessary. Considering what UPS charges, I might be better of to rent a car and deliver them in person!
PS, I get to buy toys on the company expense account, if it is nesessary. Of course, I'm the one who decides that 😛 . I'm wondering what is the most decently priced hand held scope/meter. I don't need alot of frequency range, I just need something that won't break tomorrow. Maybe the day after. I expect Fluke to be out of the question. Too much expense, not enough need for the unit. Yah never know though, I tend to do interesting mods and the like on video gear, so... residual noise needs to be measured! Any units that strike a fancy?
PS, I get to buy toys on the company expense account, if it is nesessary. Of course, I'm the one who decides that 😛 . I'm wondering what is the most decently priced hand held scope/meter. I don't need alot of frequency range, I just need something that won't break tomorrow. Maybe the day after. I expect Fluke to be out of the question. Too much expense, not enough need for the unit. Yah never know though, I tend to do interesting mods and the like on video gear, so... residual noise needs to be measured! Any units that strike a fancy?
Hi Ken,
Kinda off topic, but here we go. I am not a fan of 'scope meters at all. The resolution is not high enough for your use. An HP scope would work very well but would not do much for your noise measurements. This is more true at video frequencies.
It sounds more like you need an audio measurement system that does spectrum analysis. An RF unit would be aimed at video but I understand you need it for your speaker work. An Audio Precision setup would be my dream come true, and would suit your needs also. I think there may be some options you would need.
I have an Audio Control SA-3050A with mics that might help you out. It's resolution is rough but will give you +- 1dB. Many speakers will cause that display to go all over the place. That's what the 4 dB / step range is for.
-Chris
Kinda off topic, but here we go. I am not a fan of 'scope meters at all. The resolution is not high enough for your use. An HP scope would work very well but would not do much for your noise measurements. This is more true at video frequencies.
It sounds more like you need an audio measurement system that does spectrum analysis. An RF unit would be aimed at video but I understand you need it for your speaker work. An Audio Precision setup would be my dream come true, and would suit your needs also. I think there may be some options you would need.
I have an Audio Control SA-3050A with mics that might help you out. It's resolution is rough but will give you +- 1dB. Many speakers will cause that display to go all over the place. That's what the 4 dB / step range is for.
-Chris
Ken,
Not ready for 220's yet. That will be a few months minimum. The output stage needs to have the voltage and current scaled up in a way that still sounds good.
You might want to hear the SA-100 first to get a general idea.
-Chris
Not ready for 220's yet. That will be a few months minimum. The output stage needs to have the voltage and current scaled up in a way that still sounds good.
You might want to hear the SA-100 first to get a general idea.
-Chris
I've got the original LAUD system. It works fine for my purposes..except for the fact that I have to get old 486's with 16 bit slots, to get it to work. I'm about to move up to the latest gear from the Liberty guy, I suspect. Leap? No. looks a bit painful MLSSA? I dunno. Pricey as heck. I jsut need basic measurements which are basic in calibration,and that's about all. That's for loudspeaker work. For the video, I generally use sound thinking, and let nature do the rest. It is good to measure, but..I've never had a video circuit die from any mods I've ever done. The only time I'll ever provide measurements is so the customer has some sort of vestigal paper to hold in their hands at the store. So they feel like the engineering side has been taken care of...for those engineering types. Who somehow need that piece of paper to make a purchase. Ie, a minimal statement as to the devies operational parameters. Many times, the results are not in the measurements, as the audio guys know.. Hopefully, they know, and realize....
As useless as a scope meater may be, it might do all I need it to do. I need and want portability. I want the Tim-the-tool-man-Taylor meter. Lab gear is for wussies. 😛 I detest shlepping real gear about. Unloading and loading the trunk of the car each day, because I might use the gear at work..and then I might use it at home.. ug. Nightmare.
Also, I tend to not use scopes, ever. I might soon, though. But, at that point, I will talk to an engineer, tell him what I am thinking, and have him design it, based on my idea for a given circuit, device, or innovation.
As for fancy gear like the AP system, can it do what the Miller analyser system does? ie, clocking jitter test work like that published in Stereophool? if it does..then I'm in. It should be modern in capacity as well. I'm not about to buy a test bed that is about to be upped in hardware design soon. I'd buy it if the system was recently re-done in terms of hardware. Of course, the last time I looked at an AP, it was on a 486 system...... what's a full AP system worth these days?
As useless as a scope meater may be, it might do all I need it to do. I need and want portability. I want the Tim-the-tool-man-Taylor meter. Lab gear is for wussies. 😛 I detest shlepping real gear about. Unloading and loading the trunk of the car each day, because I might use the gear at work..and then I might use it at home.. ug. Nightmare.
Also, I tend to not use scopes, ever. I might soon, though. But, at that point, I will talk to an engineer, tell him what I am thinking, and have him design it, based on my idea for a given circuit, device, or innovation.
As for fancy gear like the AP system, can it do what the Miller analyser system does? ie, clocking jitter test work like that published in Stereophool? if it does..then I'm in. It should be modern in capacity as well. I'm not about to buy a test bed that is about to be upped in hardware design soon. I'd buy it if the system was recently re-done in terms of hardware. Of course, the last time I looked at an AP, it was on a 486 system...... what's a full AP system worth these days?
Hi Ken,
The AP system has been updated. Need to look on their site for $$. I think they can be configured as you need and that includes jitter (my HP 5335A and most HP scopes do jitter). Here is a link for you.
http://www.audioprecision.com/index.php
That should keep you busy. Waterfalls would be great. That would also apply to amps and preamps.
-Chris
The AP system has been updated. Need to look on their site for $$. I think they can be configured as you need and that includes jitter (my HP 5335A and most HP scopes do jitter). Here is a link for you.
http://www.audioprecision.com/index.php
That should keep you busy. Waterfalls would be great. That would also apply to amps and preamps.
-Chris
After about an hour of searching, all I can say is that no-one provides a price of any kind. Perhaps they require a chair and a bucket to deliver the price to you? You hear the price...you fall in to the chair, and throw up into the bucket.
Some marketing jingle for them: "Measuring audio gear has never before been so expensive".
What is the average price you have heard for a audio measurement set-up? Ie, the system two.
Some marketing jingle for them: "Measuring audio gear has never before been so expensive".
What is the average price you have heard for a audio measurement set-up? Ie, the system two.
Hi Ken,
This would be like buying a car in that it depends upon the options you want. The darn things are so configurable. In their favour, they are a test standard and are automated to run a series of tests if you want to. I will ask an old friend who has a system one.
I do know they aren't cheap.
-Chris
This would be like buying a car in that it depends upon the options you want. The darn things are so configurable. In their favour, they are a test standard and are automated to run a series of tests if you want to. I will ask an old friend who has a system one.
I do know they aren't cheap.
-Chris
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