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Can't resist..... must .... have.... XS ..... layout and solutions.... damned you Zen Mod ... LOL.
I have some material to go over and collect, but in the meantime, what is beyond XS in your opinion ?
I'm going to make my first XS preamplifier entry here.
First thing first, the UGS and Muses go together hand in hand and while an inductive transformer based preamplifier like the Iron Pumpkin indeed might outperform the UGS-XS, I stand to win either way, because, the XS version is ultimately something I would consider for a XA25 version, at least some of the solutions for biasing, dc servo and so on and the power amplifier automatically use a beefier gain stage. Either way, the UGS6 stage and its derivatives is something I will need moving forward, so make the best out of it.
So I spent some time yesterday digging up replacement FETs for the XA25/XS gain stage and arrived at this:
Zen: Do you think the XS is an exercise in narcissism ... LOL
First thing first, the UGS and Muses go together hand in hand and while an inductive transformer based preamplifier like the Iron Pumpkin indeed might outperform the UGS-XS, I stand to win either way, because, the XS version is ultimately something I would consider for a XA25 version, at least some of the solutions for biasing, dc servo and so on and the power amplifier automatically use a beefier gain stage. Either way, the UGS6 stage and its derivatives is something I will need moving forward, so make the best out of it.
So I spent some time yesterday digging up replacement FETs for the XA25/XS gain stage and arrived at this:
- JFet: The same
- BJT: Original is 2SC4793/2SA1873 and can be replaced with TTC011B/TTA006B which is identical except on one point, Pd is down from 2W to 1.5W. But a better BJT is the TTC004B/TTC004B which have better Cob and a better or higher Ib/Ic relationship.
- MOSFET: Original is 2SK2013/2SJ313 but this can be replaced with IRF610/510 and IRF9610/9510
Zen: Do you think the XS is an exercise in narcissism ... LOL
It wasn't me who mentioned XS, you did.. I blame you ... LOL ... I was writing a reply and then stopped. So I am making a new one.
I have found 7 pages, including two of your blog articles, talking about the Iron Pumpkin and some other stuff. That is an impressive amount of threads for "one" preamplifier, so naturally, I want to go over them. I did notice you have an active JFet stage, and since you do, I am thinking... one could include the ability for the preamplifier to be active H2 dominant via Schade and/or H2 generator - put this is pure speculation atm.
The UGS6 and XS gain stage will still have a life in the differential amplifier no matter what happens to the UGS Muses edition - but, one shouldn't let pride or history prevent personal and gadget growth. Plus, if the UGS Muses preamplifier changes so much (internally) that it no longer qualify being called a UGS Muses, then this thread stops and I will reorganize things and some time later create a new thread for the new endeavour. No matter, the volume wheel and LED matrix display will carry over.
I remember when I stumbled upon the picture of the Luxman CL-1000 volume attenuator and thinking: They must know something I don't.
I have found 7 pages, including two of your blog articles, talking about the Iron Pumpkin and some other stuff. That is an impressive amount of threads for "one" preamplifier, so naturally, I want to go over them. I did notice you have an active JFet stage, and since you do, I am thinking... one could include the ability for the preamplifier to be active H2 dominant via Schade and/or H2 generator - put this is pure speculation atm.
The UGS6 and XS gain stage will still have a life in the differential amplifier no matter what happens to the UGS Muses edition - but, one shouldn't let pride or history prevent personal and gadget growth. Plus, if the UGS Muses preamplifier changes so much (internally) that it no longer qualify being called a UGS Muses, then this thread stops and I will reorganize things and some time later create a new thread for the new endeavour. No matter, the volume wheel and LED matrix display will carry over.
I remember when I stumbled upon the picture of the Luxman CL-1000 volume attenuator and thinking: They must know something I don't.
The Luxman CL-1000 is a +$20k history.
Inductive vs resistive volume attenuation.
Alright, a few days have passed and I have come to a conclusion which goes as follow.
I have read numerous articles, forum entry's and spoken to a few who actually have both inductive and resistive volume attenuators and some comments have even made it to this thread, and while its not a clear cut case were one can always say: "alright, this is the best one", I can see a trend. Discrete resistors and mechanical attenuators is a subculture of audio equipment alongside inductive volume attenuators, both transformer and autoformer is lumped together here for ease of argument and I am not jumping into which is best in either camps.
While either solution have its pro and cons, of which some have been debated, by non other than me, since I now did spend some extra time going over the whole topic, something stood out and that is: Very few people have issues with the MUSES digital volume chip. Spite being a resistive attenuator, this is a precision and high grade or quality. Quite and precis. Neither does it appear to remove musical quality, it is more neutral than anything else, which ofc is a positive. This gives the engineer a larger pallet to work with and he/she can tune the electronics to his/her own flavor.
Moving over to inductive for a moment and its a completely different ballgame. Transformers in the audio chain tend to divide people. They either like it or they don't, for transformers tend to be a bit mellow or soft. Midrange forward comes to mind which can make the presentation laid back and relaxed, and yes, many people like this character. But defining it as better is something we cannot do since it often roles of the highs, hiding details and resolution, and before you attack this statement, be aware that it came from many users and not just one.
And its not always about the technology as a whole, no no, its much more complicated than that. The core material used, winding techniques, the use of toroid, EI or double C-core, if it is shielded or not.... and so on. Lundahl talks about the difference of Amorphous and MU metal differences, beyond that you have Finemet or nanocrystaline, on top of that, you have copper vs silver debates. This is not limited to Lundahl, this is common knowledge in the tube and attenuator aspect of it also matters. Doesn't sound like a simple cut case to me. If you want a good AVC/TVC, you have to pay big dolla.
https://www.lundahltransformers.com...een-mu-metal-and-amorphous-core-transformers/
Then there is resistive which can be divided into traditional wire or film type and light dependent types. All ofc have flavor and sound profiles, some better, some worse - similar to what can be said about the former.
To be honest, I could probably spend years just investigating both and I would probably conclude with: It depends.
And right now, it depends, isn't helping nor is or was that my goal. While inductive have some nice benefits over resistive, inductive also suffer from something important, namely memory or the time it takes for the core to lose its stored energy. If you didn't understand this part, then think in terms of ported enclosure and the effect it has on... drum roll: transient performance (smearing). Any electrical or mechanical system that stores energy longer than it need to is bad for audio. That is why, when Finemet or noncrystalline cores are talk about in terms of higher resolution and better resolving than amorphous, know that this is directly related to core memory or in technical terms: Transformer hysteresis. Noncrystalline is also 5-6 times more expensive.
Back to the MUSES IC. If the chip and resistors found inside were of mediocre or poor quality, I am confident it would not find its way into $38,000 preamplifier.
The good news is that the UGS Muses Scion is alive and doing well and development continues. Be aware of the fact that I paused this project back in November 2020, not sure what was going to happen or when. I am glad I did for it gave me time to reflect, look at other options and learn a thing or two. And yes, thanks to Zen, I have looked at the XS preamplfier and it does indeed have some nice additional features which I would like to use in the Scion preamplifier ... wink wink.
The work I perform on the pre will nicely transition over to the power amplifier since it will use the same gain core structure, so, a lot to win on spending the time. Now that I know what I want it is easier to go in with a better planted enthusiasm, but keep in mind. I am not a trained engineer, so everything is new and I have to learn about the fundamentals. Looking forward but will take yet more time.
So yes, that's that for now.
Alright, a few days have passed and I have come to a conclusion which goes as follow.
I have read numerous articles, forum entry's and spoken to a few who actually have both inductive and resistive volume attenuators and some comments have even made it to this thread, and while its not a clear cut case were one can always say: "alright, this is the best one", I can see a trend. Discrete resistors and mechanical attenuators is a subculture of audio equipment alongside inductive volume attenuators, both transformer and autoformer is lumped together here for ease of argument and I am not jumping into which is best in either camps.
While either solution have its pro and cons, of which some have been debated, by non other than me, since I now did spend some extra time going over the whole topic, something stood out and that is: Very few people have issues with the MUSES digital volume chip. Spite being a resistive attenuator, this is a precision and high grade or quality. Quite and precis. Neither does it appear to remove musical quality, it is more neutral than anything else, which ofc is a positive. This gives the engineer a larger pallet to work with and he/she can tune the electronics to his/her own flavor.
Moving over to inductive for a moment and its a completely different ballgame. Transformers in the audio chain tend to divide people. They either like it or they don't, for transformers tend to be a bit mellow or soft. Midrange forward comes to mind which can make the presentation laid back and relaxed, and yes, many people like this character. But defining it as better is something we cannot do since it often roles of the highs, hiding details and resolution, and before you attack this statement, be aware that it came from many users and not just one.
And its not always about the technology as a whole, no no, its much more complicated than that. The core material used, winding techniques, the use of toroid, EI or double C-core, if it is shielded or not.... and so on. Lundahl talks about the difference of Amorphous and MU metal differences, beyond that you have Finemet or nanocrystaline, on top of that, you have copper vs silver debates. This is not limited to Lundahl, this is common knowledge in the tube and attenuator aspect of it also matters. Doesn't sound like a simple cut case to me. If you want a good AVC/TVC, you have to pay big dolla.
https://www.lundahltransformers.com...een-mu-metal-and-amorphous-core-transformers/
Then there is resistive which can be divided into traditional wire or film type and light dependent types. All ofc have flavor and sound profiles, some better, some worse - similar to what can be said about the former.
To be honest, I could probably spend years just investigating both and I would probably conclude with: It depends.
And right now, it depends, isn't helping nor is or was that my goal. While inductive have some nice benefits over resistive, inductive also suffer from something important, namely memory or the time it takes for the core to lose its stored energy. If you didn't understand this part, then think in terms of ported enclosure and the effect it has on... drum roll: transient performance (smearing). Any electrical or mechanical system that stores energy longer than it need to is bad for audio. That is why, when Finemet or noncrystalline cores are talk about in terms of higher resolution and better resolving than amorphous, know that this is directly related to core memory or in technical terms: Transformer hysteresis. Noncrystalline is also 5-6 times more expensive.
Back to the MUSES IC. If the chip and resistors found inside were of mediocre or poor quality, I am confident it would not find its way into $38,000 preamplifier.
The good news is that the UGS Muses Scion is alive and doing well and development continues. Be aware of the fact that I paused this project back in November 2020, not sure what was going to happen or when. I am glad I did for it gave me time to reflect, look at other options and learn a thing or two. And yes, thanks to Zen, I have looked at the XS preamplfier and it does indeed have some nice additional features which I would like to use in the Scion preamplifier ... wink wink.
The work I perform on the pre will nicely transition over to the power amplifier since it will use the same gain core structure, so, a lot to win on spending the time. Now that I know what I want it is easier to go in with a better planted enthusiasm, but keep in mind. I am not a trained engineer, so everything is new and I have to learn about the fundamentals. Looking forward but will take yet more time.
So yes, that's that for now.
you need to learn to make choices by your own ears and brain, and even then no-one is entitled to write 15ooops-10 commandments for others to follow
Catch 22 - after decades of messing around, I'm happy to trust in judgment of just few people - these not just knowing what to listen to, but also sharing same preferences with me ( or vice versa)
only that way someone else's judgment is applicable for my choices
one fact alone is wrong in what you wrote above - when properly done, AVC equipped gadget is without own character - confirmed with both extensive measurements and listening tests; less than perfect examples of arrangement (non buffered or measly buffered) aren't representative
now, what is that - warming each different Greedy Boy, that's another story - strictly defined by personal preferences and taste
Catch 22 - after decades of messing around, I'm happy to trust in judgment of just few people - these not just knowing what to listen to, but also sharing same preferences with me ( or vice versa)
only that way someone else's judgment is applicable for my choices
one fact alone is wrong in what you wrote above - when properly done, AVC equipped gadget is without own character - confirmed with both extensive measurements and listening tests; less than perfect examples of arrangement (non buffered or measly buffered) aren't representative
now, what is that - warming each different Greedy Boy, that's another story - strictly defined by personal preferences and taste
Take not that I didn't say I would never build an inductive volume attenuator, I merely expressed not right now 
As an example, I enjoy harmonic content, Triode behavior, just not the electric hum in the background and SS can mimic a triode, so therefore, such a circuit will be embedded in the preamplifier. That is by choice and will be by design.
As an example, I enjoy harmonic content, Triode behavior, just not the electric hum in the background and SS can mimic a triode, so therefore, such a circuit will be embedded in the preamplifier. That is by choice and will be by design.
If you find it difficult to decide between different types of volume control, just keep your design modular so you can try different options. However, make sure to get going with that volume wheel on a big bearing. I can't wait to see this becoming real
I will work for the UGS Muses Scion as described incl XS expansion. With that in mind, the MCU will be adaptable (in the background) to either inductive or resistive attenuation via an IO Expander which expands the number of input/output (I/O) ports (channels) via the I2C-bus. 1 port can be transformed into 10, 30, etc which in turn controls the relays used to switch the taps/winding of AVC/TVC or a resistor bank. Once the encoder communication and display communication have been established, it should be relatively simple to expand the MCU with the IO Expanders.
I say relative because programming is the part that scares me atm, but I know there is a ton of help on the net, I also have the MUSES library for the Arduino and so on, so once the hardware is in place, according to the necessary logic, I will start looking at the software control. But that will come after I have worked out the updated gain stage, the heart of the system. When time comes, this needs to be breadboarded and tuned using relatively inexpensive TH components. That will actually be fun. I have a Tectronixs 465B, Deer Dee LCR which will get some differential probes, some UniT DMMs and a folder for a nice FET curve tracer found via AudioXpress. I will also build a measurement device to be used with REW ... I think it was REW, found here in diya..
So yes, looking good ... hope that clams your "worries"
Also, going to check out some bearings soon
I say relative because programming is the part that scares me atm, but I know there is a ton of help on the net, I also have the MUSES library for the Arduino and so on, so once the hardware is in place, according to the necessary logic, I will start looking at the software control. But that will come after I have worked out the updated gain stage, the heart of the system. When time comes, this needs to be breadboarded and tuned using relatively inexpensive TH components. That will actually be fun. I have a Tectronixs 465B, Deer Dee LCR which will get some differential probes, some UniT DMMs and a folder for a nice FET curve tracer found via AudioXpress. I will also build a measurement device to be used with REW ... I think it was REW, found here in diya..
So yes, looking good ... hope that clams your "worries"
Also, going to check out some bearings soon
point was - you're reading too much, seeking advice and opinions too much, then making judgement without even stepping a toe in the poolTake not that I didn't say I would never build an inductive volume attenuator, I merely expressed not right now
I mean - I can easily skip this thread whenever I want, but 355 posts are about making and changing objectives, and (maybe I was sloppy reader) I didn't read that you actually heard any of significant examples of approach or arrangement
if nothing else, time to get to FiFi Saloons, having gear of interest; use your ears
really friendly advice ....... I had my share of Rainbow chase ...... and only when I started trusting in my own practical experience and hearing, I started building - if not successfully, then with joy, at least
I am not an audio toddler, I have some references .. .
Mostly for loudspeakers, which was what I was going to build and develop. I never intended to spend this much time on the gear, but here we are and since differential amplifiers are either rare or expensive, the more I learned the more I realized I wanted to build my own stuff and save a few dollars. So now it is a matter of following through and make things happen.
Once the pre- and power amplifier have been assembled, then I can get an RME professional d/a conv and assemble my Yamamoto YDA-01B tube output stage d/a conv, two very different approached, that will be fun to explore and experience.
Like you say, get more of my own experiences. That's whats so fun about audio. One mans dream is another nightmare... #357
.Mostly for loudspeakers, which was what I was going to build and develop. I never intended to spend this much time on the gear, but here we are and since differential amplifiers are either rare or expensive, the more I learned the more I realized I wanted to build my own stuff and save a few dollars. So now it is a matter of following through and make things happen.
Once the pre- and power amplifier have been assembled, then I can get an RME professional d/a conv and assemble my Yamamoto YDA-01B tube output stage d/a conv, two very different approached, that will be fun to explore and experience.
Like you say, get more of my own experiences. That's whats so fun about audio. One mans dream is another nightmare... #357
Dear all and to those who are interested.
I started this thread on 2019-06-23 with the ambition to change the UGS Muses a smidgen such that it got an appearance that suited me personally a bit more, not realizing the massive undertaking due to pure naivety. I'll be the first one to publicly mention and admit it, I was naive. Being naive is a great opportunity to learn, grow and start fresh. A project can start and end with the ambition to return at a later stage, which is an indication of what is going to happen. This sounds worse than it is because I am not pausing the project, au contraire, I am accelerating the project.
Rather than making the "mistake" of maintaining the project in blog form, this comes to an end such that I can take a step back and focus, learn and develop both the pre- and power amplifier with a new set of tools and these tools are in part a greater understanding what I really want and in part with the aid of other engineers and creations. My goal is and never was to create something completely new but slightly improve it, as I saw the improvements. And while this still holds true, it is no longer limited to components only but structure and operation as well. A clear expansion of the project as a whole and to the reason why I am co-developing both the pre- and power amplifier, this is down to some simple reasons.
Over the last couple of days and weeks, I had the opportunity to look at different solutions and method's for which audio is manipulated, amplified and enjoyed and in so doing realizing or come to a conclusion on what to do, which is:
I'd like to proceed with the UGS Muses Scion project and expand it, such that it is closer to its full potential. But this is not a small task and I have realized that it will take a great piece out of me to reach. I am very much looking forward to it, I feel excited and its going to be fun. I need to properly learn the operation of differential pairs, gain stages, SuperSymmetry, operation and design of opto-active CCS stages, learn the tricks of Feed forward and Feed back system and finally, how to "manipulate" transistors to deliver their best. I also need some basic ways to measure once I start breadboarding and tune the circuits, and this too is an investment. Not everyone is blessed with a pile of money they can throw at multiple projects, here, planning is my best friend.
As to the reason for co-developing both the pre- & power amplifier, this is simply down to the gain stage which will be more or less the same in both apparatus and since I need both a pre- & power amplifier for playback, it only makes sense to work on both. But I am not alone here, I have several projects to draw inspiration and knowledge from, some found here on diya and some found elsewhere, which are very similar. Some even tie together more than they realize and others contain sections which is very useful outside of themselves. While N. Pass and W. Colburn is a HUGE inspiration and involvement (on paper), there are others that bring great value and in due time, the sources will be disclosed.
But not in this thread. In time, when I have real stuff to present, I will create a new thread which will be founded on a better idea of how to manage a diya thread. This thread will simply be called:
I started this thread on 2019-06-23 with the ambition to change the UGS Muses a smidgen such that it got an appearance that suited me personally a bit more, not realizing the massive undertaking due to pure naivety. I'll be the first one to publicly mention and admit it, I was naive. Being naive is a great opportunity to learn, grow and start fresh. A project can start and end with the ambition to return at a later stage, which is an indication of what is going to happen. This sounds worse than it is because I am not pausing the project, au contraire, I am accelerating the project.
Rather than making the "mistake" of maintaining the project in blog form, this comes to an end such that I can take a step back and focus, learn and develop both the pre- and power amplifier with a new set of tools and these tools are in part a greater understanding what I really want and in part with the aid of other engineers and creations. My goal is and never was to create something completely new but slightly improve it, as I saw the improvements. And while this still holds true, it is no longer limited to components only but structure and operation as well. A clear expansion of the project as a whole and to the reason why I am co-developing both the pre- and power amplifier, this is down to some simple reasons.
Over the last couple of days and weeks, I had the opportunity to look at different solutions and method's for which audio is manipulated, amplified and enjoyed and in so doing realizing or come to a conclusion on what to do, which is:
I'd like to proceed with the UGS Muses Scion project and expand it, such that it is closer to its full potential. But this is not a small task and I have realized that it will take a great piece out of me to reach. I am very much looking forward to it, I feel excited and its going to be fun. I need to properly learn the operation of differential pairs, gain stages, SuperSymmetry, operation and design of opto-active CCS stages, learn the tricks of Feed forward and Feed back system and finally, how to "manipulate" transistors to deliver their best. I also need some basic ways to measure once I start breadboarding and tune the circuits, and this too is an investment. Not everyone is blessed with a pile of money they can throw at multiple projects, here, planning is my best friend.
As to the reason for co-developing both the pre- & power amplifier, this is simply down to the gain stage which will be more or less the same in both apparatus and since I need both a pre- & power amplifier for playback, it only makes sense to work on both. But I am not alone here, I have several projects to draw inspiration and knowledge from, some found here on diya and some found elsewhere, which are very similar. Some even tie together more than they realize and others contain sections which is very useful outside of themselves. While N. Pass and W. Colburn is a HUGE inspiration and involvement (on paper), there are others that bring great value and in due time, the sources will be disclosed.
But not in this thread. In time, when I have real stuff to present, I will create a new thread which will be founded on a better idea of how to manage a diya thread
. This thread will simply be called:
- The Scion Pre- & Power amplifier -
So with this in mind, its time for this thread to calm down and take a step back in favour of something better. It has served me well, but we all outgrew it in one way or other, but don't worry. The volume wheel and centre display is not going away, after all, it is a core function and appearance just like a UGS gain stage and SuSy structure is the heart and soul of both. I don't have much more to add and you simply have to wait until the [The Scion Pre- & Power amplifier] thread appears. I will ofc link to it in this thread.
Have a nice time until then.
This entry will be one of the last regarding this project. After months of considerations and evaluations of feasible options I have finally landed on what I think will be the overall best option in the end. I have decided to abandon the UGS platform in favour of a vacuum tubes and in the form of Allan Wright's fully differential platform.
I've been back and forth on SS and tubes, but in the end, tubes have won me over and I cannot deny it any longer. There still things to be discovered for that project, something which will coexist with a few other projects. But in due time I will create a new and fresh thread called: The Audiopath series – Pre. It will be part of my audio gear journey of actual devices that I will build.
I've been back and forth on SS and tubes, but in the end, tubes have won me over and I cannot deny it any longer. There still things to be discovered for that project, something which will coexist with a few other projects. But in due time I will create a new and fresh thread called: The Audiopath series – Pre. It will be part of my audio gear journey of actual devices that I will build.