As I said I think we have realized our goals in this thread. My LD is a "value" piece of kit, part of the fun was to achieve what we have without spending a fortune.
Indeed.
I personally wouldn't spend a thousand dollars or euros on an amp, but I can understand that DIY is not for everybody. Surely the LD has a recognizeable name, so there is resell value.
It does have a flavour which I like but I think it has eenough transparency. It can sound stunningly real.
Not sure if this applies to you specifically (the above quote would suggest no), but just to bring the point home;
Transparency and realism are not mutually exclusive in any way. In fact if the recording sounds 'real', then a transparent amp will convey a most convincing amount of realism.
Just to bring an example, back when I was still in possession of my flagship amp, I had a cello player friend of mine listen it. He brought a recording of his cello master. The recording was very well made, and very lightly produced.
When we played it, he was stunned at how much it sounded like he was playing in the same room with us. He even recognized the cello his master uses, by sound. He said he hasn't been able to hear that specific signature on any other system.
Now that I call transparency. The realism was there in the recording, and the system allowed it to be played back, to be reproduced without destroying it somehow.
The easiest way to destroy a delicate signal with complex spatial and harmonic signatures (i.e. realism) is to splash some extra harmonics (no matter how benign or natural) on top of it. But more on that later.
I think the circuit mod points you raise are interesting points for future projects but I can't really see that we would be able to substantially alter the circuitry of the LD. I may be wrong.
I suspect you are not wrong. Chassis size is the biggest constraint. If you start a new chassis, why not go for a different, fundamentally better design anyway.
You can glue or use cable ties.
Superglue is my most important material after solder and wire. Look at Sonics great quality pictures, he has adopted the superglue approach as well. What superglue cannot fix cannot be fixed.
1 - There is the question of substandard recordings which can sound horrendous but are much better to listen to if some sort of rounding off process occurs.
2 - Then there is the point about "artificial" software equalizers which I don't like, therefore if the house sound of the amp is sufficiently to your liking that you can listen to poor quality recordings and you don't feel you need an equalizer that's all to the good.
3 - Finally I've been to many live concerts and for me to get 90% of the sound of the live concert is OK. I get this with the LD with Tungsol tubes. I know they are not accurate in sound reproduction but to have a near enough reproduction of a live concert, albeit with the edges rolled off, which I personally like, is fine.
I also prefer some roll off for headphones because it makes listening less fatiguing.
This message could've been written by past me, I've been in this place. I listen to a lot of old stuff that is recorded quite poorly. One of the best examples is the catalogue of Robert Johnson. While I thoroughly enjoy his music, the sound quality is so rough it can be quite taxing to listen to.
Fortunately I found a way around this.
What the last sentence of point 3 tells me is that your system produces some amount of harmonic content, more than it should according to your ears. Let's go back to this:
The easiest way to destroy a delicate signal with complex spatial and harmonic signatures (i.e. realism) is to splash some extra harmonics (no matter how benign or natural) on top of it.
Distortion measurements are usually done using as pure a sine wave as possible, then looking at the output and it's harmonic content. Let's say the output at 1kHz has some 2H and less 3H, no higher harmonics.
Ok then, what happens when you input into this hypothetical amp a signal with equal amounts of 1kHz and 3kHz. What comes out?
Both of these signals produce their 2H and 3H. Then these 4 newly created harmonics also SUM TOGETHER, creating 4H, 5H, 6H and 7H at lower levels. So now we have quite a complex mat of harmonics from these two (1kHz and 3kHz) inputs.
Now imagine you input a complex signal with multiple instruments into this amp.
You are going to have a mess. Granted these sum harmonics are at a low level, but the higher you go, the nastier they are even at low levels.
Incidentally this sum effect is how and why great amounts of gNFB produces a complex mat of very low level harmonics. It's an "infinite sum loop" to simplify a bit.
Wave physics 101. I remember this part from my days in EE university (I changed majors since). Think about a still surface of water. You drop a perfect round object into water; it creates a ripple. The ripple waves are bigger the closer they are to the point of impact (W1 and W2 are biggest, rest are quite small in comparison).
Now if you drop two round objects of about same size simultaneously, they will exhibit the same ripple behavior close to the impact site, but where the waves meet each other, they produce a lot of very small erratic ripples (higher harmonics of the wave), because the waves sum.
This metaphor is not 100% applicable to electric waves, but in essence the same thing happens with them.
For this reason alone (to avoid complex IMD products) I personally would like to minimize the amount of harmonics my amp adds to the signal.
My SE amps have a substantial amount (depends on what's the comparison I guess?) of 2H and some 3H. While they sound very nice, there is a 'something' on top of the sound at all times. The dynamics ("the kick") largely compensates for this when using speakers, and I wouldn't make a SE headphone amp anymore.
This is also the 'dirt' / 'veil' that Sonic described in comparing amps in another thread.
Distortion (however 'benign') always masks detail. Detail conveys realism; the subtle cues that come from the room, or from the instrument. One consistent comment I get from people who listen to open loop low THD amp for the first time is that they become suddenly hyperaware of the fact that the instrument they are listening to has a physical form. Like you cannot stop imagining the acoustic guitar you are listening, because you hear these subtle audio signatures that come from the body of the guitar.
This effect is most pronounced on human voices for understandable reasons.
These audio cues are transmitted in the higher register. You can rough test this by cutting frequencies above 12kHz and see what happens to spatial information. Now if your amp has even a tiny amount of higher harmonics, you cannot hear these, they are drowned in these harmonics.
Now to bring it back to your quote;
A rough recording with quite high distortion is going to sound bad when EVEN MORE distortion is added, because it will further mask the "realism information" and it will produce nasty IMD products. Get a cleaner OPEN LOOP amp and these problems are greatly alleviated. At least this has been my finding.
My experiences with shaping distortion back in the instrument amp world are about 60 to 70% on CLEAN guitar. Plug a guitar to a HIFI amp and play clean. It's horrible. The 'clean' guitar sound, whenever nice sounding, is in fact quite distorted (in HIFI terms). There is no reason to add any distortion during reproduction, if a nice guitar amp was used; a transparent amp will make it sound every bit as nice as it was in the studio. Unless the engineer was an idiot.
