This is the sort of question that would elicit a 10 page thread in a couple of days on DIY Audio . There's a corker there at the moment where drlowmu has stirred up some of the regulars.
I'm not sure what the answer is. I know my Fostex 208s can sound really rather uninspiring for an hour or more if they've not been used for a while. But this is presumably mechanical rather electrical as has been said.
I'm inclined to think that components do make a difference (not everyone on DIYA agrees with that in all cases) but whether they improve with burn in I not sure. I do think that everyone hears things differently and is sensitive to things others aren't. Regarding AB testing I think Nick G's point about not being able to forget things you've heard is important.
True, well-spotted Dave.
If we had a relatively small group of people at Owston it might be possible to rig-up a demo . We'd need to
(i) have a pretty good-sounding system
and
(ii) not have a room full of people talking over the music (!)
Easiest is probably a relatively inexpensive electrolytic by-pass cap on an output valve - if you end up A/B-ing too much and threaten to run-in the component, you could bring another one out of the box ; but I suppose input transformers would be OK, if anyone had an extra pair of the same input transformers they are using, that they wouldn't use between now and the next Owston ... ?
"Once you find out ... the Circumstances ; then you can go out"
I have really mixed feelings about questions like this. On the one hand, if you disagree with the principle, you get clobbered so, how is a REALLY HONEST reply even possible?
I think there is no argument about transducers. The question is, do they ever break in, or do we need to continuously exercize them. I am pretty sure that transducer suspension break in is measurable.
Now about parts, electrolytic caps work by chemical reaction, so there is something measurable going on that some claim to hear and others not. How much can really happen in a foil cap? a resistor?
Tubes wear out with time so it is an easy call to say that the sound changes.
My personal take? The humidity in the air, airpressure or temperature in the room changes the sound of speakers more than anything else. Phono cartridges are very sensitive to temperature (or maybe it is the surface of the LP?). Electronics are sensitive to the quality of the electricity. Around 6 o'clock in the evening is about the worst time for me to try and seriously listen to anything. I have to say though, all comments without me being in the room I take with a grain of salt. What is posted may or may not be true, honest, wishful thinking or anything else. Even when I have planned listening time with friends, there always tends to be some kind of excuse. I believe this is because of the expectation to notice "something", to be competent, have golden ears.
My question to this question would be: what is the ultimate reason that a particular person is "into audio". What part of that reason needs burn in? Does music become secondary because of "break in" issues?
I play trumpet professionally and can vouch for an effective "warm up". I have a 15 to 20 minute routine for maintenance of all of the mechanical playing necessities. My audio also has a warmup procedure. After 15 to 20 minutes, I am ready, and for the most part my audio always has been too.
The only piece of kit that really took a long time to settle in was my AKG K701 headphones. It took 2 weeks of loud music (not on my head) before they had a balanced frequency response and were as fun to listen to as the demos that I was loaned. Mechanically "breaking in" the ear cushions (to get the transducers closer to my ears) provided the last 10% of SQ. Now after 4 years the headphones always sound good after the obligatory warmup.
One last bit of heresy: if our designs are so critical to parts break in, is it even a good design? If the electrical specifications on parts were so "variable" could any circuit work for more than a short period?
SteveTheShadow wrote:In fact I have heard burn-in do the opposite of what it usually does. Yes I have heard things get worse over a period of time, despite the fact that voltage measurements and scope probing reveals no change in conditions.
That's a strange one, but it has caused me often to abandon or dismantle something that sounded great, when newly built.
This is a very good point Steve, I have heard this happen too . It often seems to be a gradually increasing too-aggressive treble , after you had a 'compromise point' after a day or two where it all sounded great. I wonder if it's due to something basic about my system ( Jono warns me that the 103R is rough at the top-end compared to things like the SPU ) or is it typical recordings ( certainly 60's pop/rock singles need some taming ! ) ? Certainly I tend to think the 'flat response' is not necessarily the ideal, if you want to play a wide variety of music . Maybe that's best handled in the speakers though - then you can let the amps be as transparent as possible ?
"Once you find out ... the Circumstances ; then you can go out"
Could this effect simply be "bad" electricity? The power grid is subject to all sorts of disturbances and I have found that aggressive treble can come and go - or disappear completely when hooked up to a regenerating UPS. The change in conditions was going IN to the power supply.
IslandPink wrote:
SteveTheShadow wrote:In fact I have heard burn-in do the opposite of what it usually does. Yes I have heard things get worse over a period of time, despite the fact that voltage measurements and scope probing reveals no change in conditions.
That's a strange one, but it has caused me often to abandon or dismantle something that sounded great, when newly built.
This is a very good point Steve, I have heard this happen too . It often seems to be a gradually increasing too-aggressive treble , after you had a 'compromise point' after a day or two where it all sounded great. I wonder if it's due to something basic about my system ( Jono warns me that the 103R is rough at the top-end compared to things like the SPU ) or is it typical recordings ( certainly 60's pop/rock singles need some taming ! ) ? Certainly I tend to think the 'flat response' is not necessarily the ideal, if you want to play a wide variety of music . Maybe that's best handled in the speakers though - then you can let the amps be as transparent as possible ?
There's probably some variability in my sound due to electricity I should do more when I get chance, with the phono amp in particular, to chase out PS noise and EMI noise . Most of my kit does use fairly old-school power supply solutions with big chokes before any regulation/shunt elements though . Also I'm lucky here that I'm not near to a lot of industry , and our electricity comes from fairly near the source ( Wylfa nuclear PS ) so it's relatively clean .
So anyway, the running-in effects tend to be progressive, for the most part, so I think they tend to outweight any mains variability .
"Once you find out ... the Circumstances ; then you can go out"
Because we are out in the sticks, our power is all over the place - we average approximately 255VAC and often exceed 260.
Thus everything sensitive is run off online UPS systems. I also have commercial lightning barriers on all three phases - so I guess our mains is pretty clean.
At least for me that removes another variable from the equation.
I'd argue that if your sound gets worse because your mains supply isn't clean, then you need to look at your power supply filtering, as clearly there isn't enough filter there.
Of course, sticking regulators on everything would help, so then all of your working voltages are held nice and constant.
Not wanting to upset anyone, but still...
Does anyone have a really big amplifier we could use as a power supply?
- could even feed it music signals.
Have to agree with Mark, component break in is fairly obvious to me. Case in point was when I got an 845 amp new. For three weeks it had almost no bass, to the point where I was going to take it to Nick's so he could measure it. It came good in the third week thankfully. I am not talking subtleties here, it was an obvious lack of bass, and no it wasn't the rest of the system as it was fine with other amps. Funnily enough I read an online review that said the same thing.
chris661 wrote:...Not wanting to upset anyone, but still...
Does anyone have a really big amplifier we could use as a power supply?
- could even feed it music signals.
The phrase you're looking for is "DC servo" - these are designed specifically for this sort of application. As it happens, I had an 800W (2 x 400W bridges) Perreaux amp that was stable & good enough for this (DC-100kHz)... but I sold it at Audio Jumble - I did offer it to DtB (who was there) but he respectfully declined
Also would need a deterministic noise injector and a variable-distortion (harmonics etc.) sine generator....
EDIT: Just thought - this is basically an H-bridge with suitable FET drivers and a variable, high-power, DC supply.
I do have a DC-600V SMPS (lab quality, Xantrex 0-600V @ 0-1.7A - earlier version of one of these: http://www.us.tdk-lambda.com/hp/product ... esys1u.htm) and knocking up a suitable bridge is not tricky - would need snubbing and protection to shelter it from the inductive load of a xfrmr, but this is exactly what I've done in the past for building solid state tesla coils...
Last edited by jack on Tue Jan 27, 2015 5:24 pm, edited 1 time in total.
Pretty sure I'm just after a really big amplifier, Nick
Something bigger than the really big old Crown amps (5000VZ etc - that one will only swing 170v RMS when bridged). My biggest amp will do 140v RMS on a bridged output - not much use for powering anything other than dim lightbulbs, really...
That said, I guess a 2:1 step-up transformer, or a variac wired backwards, would get it sorted. Anyone interested in feeding mains-music into their amps?
I'd happily lend a big amplifier to try - 2.5kW will be plenty, right?
One of Philip's 1KVA isolation transformers should do nicely - they have dual isolated 115V primaries that could be wired in parallel (if you get the phasing right!)...
An AWG (Arbitary Waveform Generator) as input to the amp would allow all sorts of tests to be made...
Excellent point. That'd give some leeway to adjust the voltage up and down, too, with up to 280v rms output on a good day.
Could try pink noise, square/triangle waves. Gotta be careful, though - I'd expect triangle waves to be nasty to rectifiers, because of the very brief current draw.
Aaaanyway, it looks to me to be fairly viable to do a super-clean mains supply. Anyone interested in playing with this?
. There's a corker there at the moment where drlowmu has stirred up some of the regulars.
