Oh, for some reason I thought it increased in screen mode.
Is this a good result for a 4P1L line stage at 11v RMS output 100k load?
The higher low frequency noise floor and harmonics below the fundamental are due to a circuit instability so they can be somewhat ignored.
It sounds just like an amplified version of the source. If I equalize the volume of a power buffered source vs the 4P1L stage I'm having a difficult time detecting a difference. Does the 4P1L not have its own sound? I thought it was supposed to sound special in some way?
Is this a good result for a 4P1L line stage at 11v RMS output 100k load?
The higher low frequency noise floor and harmonics below the fundamental are due to a circuit instability so they can be somewhat ignored.
It sounds just like an amplified version of the source. If I equalize the volume of a power buffered source vs the 4P1L stage I'm having a difficult time detecting a difference. Does the 4P1L not have its own sound? I thought it was supposed to sound special in some way?
I have not done any tube-rolling in my amp, but I can say that the measured values of my tube-tracer (roetester v9) has shown significant differences in the vintages. Strongest those from 1959 (got a batch of 80 pcs from russia). follwoed by the sixties. You can be lucky to get as well a strong from the seventies or eighties, but the percentages where more like fifities: 70% strong vs. seveties 30%. And we talk 25-35% more emission etc here, so not a small difference.
I changed nevertheless to 801A and all my microfonic issues /ringing where gone.
Distortion looks fine as expected with this valve. A zoom at LF would be ideal to see if you have a higher mains hum or byproducts from rectification. It can be seen on the image as well.
This stage is meant to be very transparent and provides a very detailed sound. If you’re looking for “colour” then isn’t the stage to use.
Perhaps you don’t need the preamp gain at all?
Ale
Some of that is due to the biasing circuit I'm using to match the tube operating parameters. It loves to be an oscillator with the gyrator in the feedback loop. I'm not knowledgeable enough at feedback and stability theory to eliminate the oscillation completely so there is LF instability still.
No certainly not, I currently only own headphones.
But I spent like a year designing this input stage, it uses one tube to attempt to cancel the other tubes distortion using antiphase currents. I figured I'd go with the 4P1L everyone was raving about and see how the design sounds. But I think I went a bit too far because it sounds like a wire with gain. I noticed that the 4P1L distortion kept going lower and lower with a higher plate bias but I ran out of power supply headroom @ 190v. It would be interesting to see where it lands with a 250v plate voltage. 28ma was the optimal idle current I found. But clearly I don't need the thing to be lower distortion than it already is.
I have an ultra ultra low distortion power buffer I designed that I used on the output of the DAC, if I compare the sound of that to the 4P1L stage, they pretty much sound the same. Maybe very slightly different with the 4P1L in the way but it's really so subtle that it's hard to tell without a selection switch to swap between the two in real time.
I think "colour" is what I need. I've been strongly considering the 01A, that tube has some "magic" in it right?
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I don't know what circuit you have here, but certainly I don't see the point on matching the operating point conditions with a specific bias servo/feedback circuit.
If the valve oscillates, then your perception of how this stage sounds is likely to be mislead by the oscillation byproducts.
Less is more sometimes, I'd keep it simple. I never liked much the DC servo sound on the preamp stages. Perhaps if you can share your design we would be able to comment further here.
If you want "colour" just bias the stage to increase the H2 content and you will get what you are looking for
Ale
It's required for my circuit to function as intended.
It only oscillates in the milihertz range. Well I mean technically if I don't provide any compensation it functions as a full on PWM oscillator, which actually works well after filtering, but I wasn't sure how to completely filter out the noise.
It's not a DC servo. Besides the entire problem I'm having is that it doesn't sound like anything at all. It sounds exactly the same as the source but louder.
As I've said I've tested this be level shifting the output volume so the 4P1L stage matches the source volume with a power buffer attached. Comparing the two reveals basically the exact same sound through my HD800, as far as I can tell.
It's basically a wire with gain. Which is what I don't want.
I can't share the design, I've spent years and many thousands on R&D of audio designs in an attempt to start an audio business. I've got all my eggs in that basket. Not that I wouldn't kill to share it. I've had to alter the design to a slightly worse performance version in order to quell the oscillation, not that I can really tell the sonic difference., but third party assistance would be awesome if it wasn't a bad idea to share my stuff.
I've been unable to discern an audible difference between 2nd harmonic @ -30db with no other harmonics below -100db and and an equivalent circuit with all harmonics below -100db, the result of the difference only being due to parts swapping. I no longer believe 2nd harmonic is responsible for adding anything good to the sound.
What's with all the talk about the 01a having a "special" sound and DHTs sounding more "magical" than IHTs and all that other jargon if all tubes sound the same in their linear range?
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Impossible.
If you have 2nd harmonics 30dB below fundamental ( power amplifier? ) the third at about -50..60dB.
Well, can’t help much this way. I also spent many hours on this design and this DIY forum is for sharing and learning. If you don’t give, unlikely you will get much in return.
Don’t expect people to do free consulting on your commercial product.
Good luck with your project.
I never asked for design consultation, which is why I didn't post a schematic. I just asked generalized questions about tube sound. Totally different topic.
Tell that to the audio analyzer. It wasn't a power amp, just an I-V stage.
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But the end result is the same, you are consulting other people with the intention of improving your product which will be sold for profit. Whether you did it in a passive way or not is entirely different.
And, I highly doubt anyone will steal your design so chill out and post the schematic if you want help. General questions most likely won't get you any specific help on your design, but good luck to you if that's all that you wish.
ON A BETTER NOTE: I GOT MY BOARDS FROM ROD!!!!!
I'z beezzz happeeezzzz
Carry on
Seems kind of ridiculous to blacklist someone for simply mentioning that they are planning to sell products they designed. What do you do when anyone from the vendors section asks a question, Ignore them?
Hmmm, I've been dying to share my designs on here for a long time, but on the other hand the only reason I'm not living on the streets is because I don't own a car and eat minimally. This is my way out, I don't know if it's wise to risk it by posting my stuff on the web.
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If I wanted design help I would have asked for it. I only mentioned my design to provide context.
My questions had nothing to do with design, I was asking for a generalized subjective opinion about tube sound. It only takes basic english comprehension and reading skills to notice that my questions went ignored and unanswered and were replaced by unrelated responses to my mentioned design.
Most of the vendors on here that I see like George from Tubelab or Nelson Pass will post schematics.
Lets take a couple steps backwards please.
My basic English reading and comprehension skills have maybe failed me. But this is what I take away from the discussion;
You have a design you worked really hard but despite all your efforts it doesn't have "the tube sound" no matter what you do.
You asked;
To which I thought you got a very accurate response of;
The plot thickens.
You then ask;
Okay you spent tons of time and money on R&D. You say you don't want any design help and you can do everything yourself but for some strange reason you want to skip some research and development like for example buying some 01A valves and trying them out to see if it's what you like. Instead you are asking about magic tubes and someone else's response is suppose to suffice for answering a question about your subjective taste in sound. BTW, if you want color I suggest picking a valve that isn't very linear to begin with.
You actually get some great advice;
Your response;
Google is your friend here. 2H is for the most part benign and may or may not give you the "tube sound". I think Ale was grabbing straws about the DC servo because of low distortion, you never tell us what you are using as a plate load. Maybe don't just change the operating point, change the load to a more vertical one to get more harmonics maybe?
Again, you say you don't need anyone's help and you have done a lot of R&D but you won't go the next step in research and development by buying some different valves and play with them to find something you like? Have you looked at the 01A plate curves? Draw some load lines and run some calculations on distortion at different operating points and loads? Run any simulations to see what the numbers look like against your calculations? The rest of us do all this and post it for the community.
If you have a good product for a market people will purchase it regardless if there is a schematic floating around on the internet or not. People are going to get offended when they offer help and then you turn around and basically say to them, no I won't share my work because I think you are going to steal it and go and sell it screwing me out of money. Which is what you are implying because if you weren't you would have said something like "I don't won't to post publicly in the thread but I will PM you my design and please don't share it.
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They can afford to. I literally can't. I want to share far more than you want me to believe me. You are mistaken if you think I like being forced into secrecy. I'm well into poverty dude. I'm a bit foolish for allocating any money on this stuff. If you can't respect that then I don't know what to say.
That costs money. Asking for subjective opinions is free. I never wanted a scientific answer. You just assumed I did. All I wanted was a lighthearted subjective opinion. Not the answer to the meaning of life.
You're making assumptions again by saying I'm not going to "take the next step". You act like asking a question on the internet cannot be done at the same time as practical research.
I know what the load lines look like. This is why I'm confused about the many claims of "unique sound" from these tubes, hence the nature of my question. You've got your panties in a bundle worrying about the mention of a design that is not relevant to the conversation. I'm sorry I even mentioned it.
True, but I'm a year or two off from being in a position to sell anything. I've got a list of ideas I still want to test and optimize before I go public. Who knows what lurkers with means could do within that time. I'm either being silly or wise, I don't know which one. But I've got too much riding on this to take chances.
I didn't ask for design help. You're still going on about that design. I should have never said anything about it. The design has literally 100% nothing to do with any of my questions, I only mentioned it for context. I have like, 20 designs, that was just an idea I was testing out.
My questions were related to the nature of tube sound, not any specific design.
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My panties are just fine
Which Ale answered almost immediately. He said the tube is transparent and if you want color pick another tube or make it distort.
And trust me, I feel you about the poverty thing. How the hell do you think I ended up here to begin with lol. I can't afford to buy my own gear so I have to scrape and save and look for deals and salvage transformers and pull tubes from old radios or find them at flea markets etc.....
I am not here to argue or fight with so I do apologize but honestly your ears are your ears, as you say you are asking a subjective question about the 4P1L or the 01A etc...... I just looked and can score an 01A for $10, I mean is that really going to push you that much farther into poverty? I don't think so. I do get it, you are just asking some preliminary questioning so don't you get your panties in a bunch (see what I did there but really my advice is just coughing up the dough and doing it yourself is the only way to see if it's what you are searching for, we can't tell you that. Sorry but there is really nothing novel out there and I don't think sharing a schematic even publically is going to kill your future business. You do know there is almost zero money to be made in this industry? This is why we do it for fun. You have to compete with China and or cater to the audiophools with snake oil BS and charge 8 million dollars for a wire. Most of the vendors I know on here have regular day jobs that pay the bills and they don't make squat for their wares. Honestly they probably are in the whole for doing it. Which is why we just do this for ***** and giggles mate. Look at Fender, the musical instrument company, you can go right on their website and they post their amplifiers schematics. Why? Because at the end of the day they know people want to go buy a "Fender" and not some dude in his basements version because people have been branded. They see logos and attitudes when they buy stuff not the engineering. They want to relate to the product. This is just my opinion.
I do wish you the best of luck on your venture. It sounds like you have put a lot of sweat into your dream. I only wish to push you to the next stage, buy some 01A's when you can and start playing with them. There are plenty of odball tubes that are cheaper. Or we can continue with the 4P1L, I mean there has to be a way to get it to make some harmonics right? What are you loading the thing with?
Let's move forward bud and talk about tubes
Which Ale answered almost immediately. He said the tube is transparent and if you want color pick another tube or make it distort.
And trust me, I feel you about the poverty thing. How the hell do you think I ended up here to begin with lol. I can't afford to buy my own gear so I have to scrape and save and look for deals and salvage transformers and pull tubes from old radios or find them at flea markets etc.....
I am not here to argue or fight with so I do apologize but honestly your ears are your ears, as you say you are asking a subjective question about the 4P1L or the 01A etc...... I just looked and can score an 01A for $10, I mean is that really going to push you that much farther into poverty? I don't think so. I do get it, you are just asking some preliminary questioning so don't you get your panties in a bunch (see what I did there
but really my advice is just coughing up the dough and doing it yourself is the only way to see if it's what you are searching for, we can't tell you that. Sorry but there is really nothing novel out there and I don't think sharing a schematic even publically is going to kill your future business. You do know there is almost zero money to be made in this industry? This is why we do it for fun. You have to compete with China and or cater to the audiophools with snake oil BS and charge 8 million dollars for a wire. Most of the vendors I know on here have regular day jobs that pay the bills and they don't make squat for their wares. Honestly they probably are in the whole for doing it. Which is why we just do this for ***** and giggles mate. Look at Fender, the musical instrument company, you can go right on their website and they post their amplifiers schematics. Why? Because at the end of the day they know people want to go buy a "Fender" and not some dude in his basements version because people have been branded. They see logos and attitudes when they buy stuff not the engineering. They want to relate to the product. This is just my opinion. I do wish you the best of luck on your venture. It sounds like you have put a lot of sweat into your dream. I only wish to push you to the next stage, buy some 01A's when you can and start playing with them. There are plenty of odball tubes that are cheaper. Or we can continue with the 4P1L, I mean there has to be a way to get it to make some harmonics right? What are you loading the thing with?
Let's move forward bud and talk about tubes