New amp build burning-in

[jojokeo]

Looking for any information regarding "burning-in" new amp builds. I've seen a couple builders do this in a few videos but the subject matter wasn't really related or they didn't go into many details. Wondering why? (is it just to put the new amp through it's paces and so they have to give some sort of name for it?) For how long? What does it supposedly do? Also, I've heard/seen a few hifi folks say their amps are harsh initially and after about three days or more they seem to settle in and get smoother? Does anyone here actually do it? Any info or links is appreciated.

[shooter]

On my "successful" builds(guitar) I burn them in for 1 reason only, if they idle for 24hrs, with intermittent playing and nothing burns up, It's good!  my 2 audio builds I sorta followed the audio guys recommendation for speaker burn-in, 10+hrs of varied music, classical being the "default".  I did hear a perceivable "smoothing" of sound in the 1st amp +new speakers, this current one I don't notice any change.  I think aside from premature failure, it's a mostly smoke n mirrors kinda thing , then again, as a salesman, you can say; "Yup, burnt it in for 20hrs with lots of Bach" 

[Ed_Chambley]

A lot of the parts manufacturers, like SoZo and Jupiter say their caps have a Burn IN period.  Sozo states 100 Hours and Jupiter states 30.

What I do is get the amp feeding back and leave it for a few days.  Remember I have an amp room that helps with the volume.  My reason is not "burn in."  My reason is to find any weak links like tubes and resistors.  I even had a OT fail while doing this.

Don't know if it helps smooth anything out, but I do think some of it is Snake Oil.

[Willabe]

What I do is get the amp feeding back and leave it for a few days. 

Like Hendricks and Santana feedback?

Speaker coils can't take that, they burn up when staying at a single frequency, can even catch fire.

I can't see how an OT or tubes could take it either.   

[tubenit]

I sorta followed the audio guys recommendation for speaker burn-in, 10+hrs of varied music, classical being the "default". 

 

I am not sure why but something about that reminded me of Monty Python skits?

With respect, Tubenit

[jojokeo]

Don't know if it helps smooth anything out, but I do think some of it is Snake Oil.

I'm a bit skeptical too Ed but that's interesting about the cap info. I've heard that caps get used to working at a certain voltage or range? Seems a bit like forming filter caps to me? But maybe there's something to this? We've all heard of power tubes being burnt-in besides speaker break-in. But on a PRS amp building vid it was more of a testing thing than an amp being left on over night or a few days for the sake of letting it run for some length of time. But I've seen a few vids where a builder will do this (and nothing more is said about it).Heck if the outside foil can make a difference then maybe there is something Sozo & Jupiter knows that we don't?

[Ed_Chambley]

What I do is get the amp feeding back and leave it for a few days. 

Like Hendricks and Santana feedback?

Speaker coils can't take that, they burn up when staying at a single frequency, can even catch fire.

I can't see how an OT or tubes could take it either.

True Brad and you are correct.  I would not recommend doing this to anyone.  It is something I do, but you do not have to have the volume of Hendrix or Santana.  Actually the last one I did I used a pedal Joe made for me.  The frequencies would change.

It is definitely stressful on the amp and speakers, but that is why I do it.  I saw a video of Eddie VH testing his gear, the EVH gear and they actually leave their new designed amps for a Month feeding back without checking on them.  They show it on youtube.  I don't think I would do this.

All I do is get basically set it up as if I were pushing it hard and leave it a couple of days.  I have never lost a speaker, but lost tubes like Sovtek 5881's.  I need to think this through more, so thank for the comment.  Last time I used a cabinet with some very old greenbacks.  Probably be better to use something no so rare.

[Willabe]

but you do not have to have the volume of Hendrix or Santana. 

I'm not sure it's just volume but that the voice coil is barely moving with a hi note/frequency, and the coil can't dissipate the heat?     

[Ed_Chambley]

but you do not have to have the volume of Hendrix or Santana. 

I'm not sure it's just volume but that the voice coil is barely moving with a hi note/frequency, and the coil can't dissipate the heat?     

Agreed! That is why I am going to start using old Hammond tone cab speaker pulls.  What I meant about the volume comment was not in regard to speakers, but the amp itself.  I always have fans running on my chassis and tubes, but I do not have a good way to cool the voice coils.  With as many speakers as I have and have had I can say I am very lucky.  I have never blown one and I prefer low wattage speakers.  For instance, I have a 30 watt Weber 12 in a 50 watt BF Bassman which I know exceeds 50 watts.  I have had speakers give out on me and have to recone, but not from intentional abuse like the feedback.

My they sound good.

I certainly not recommending this to anyone and I doubt I would do it if I did not have a lot of gear.

[Ed_Chambley]

Don't know if it helps smooth anything out, but I do think some of it is Snake Oil.

I'm a bit skeptical too Ed but that's interesting about the cap info. I've heard that caps get used to working at a certain voltage or range? Seems a bit like forming filter caps to me? But maybe there's something to this? We've all heard of power tubes being burnt-in besides speaker break-in. But on a PRS amp building vid it was more of a testing thing than an amp being left on over night or a few days for the sake of letting it run for some length of time. But I've seen a few vids where a builder will do this (and nothing more is said about it).Heck if the outside foil can make a difference then maybe there is something Sozo & Jupiter knows that we don't?

I was given a huge box of Sozo caps.  Yellows, vintage and some of the blues.  Long story short, Sozo was making good on a bet they lost and a friend of mine gave them to me.  I still have a bunch and use them everywhere.  No I say that to say this.  I have quite a bit of experience using them and find them to have a nice Mallory type tone, but 100 hours.  I just don't see how.

I still grab every blue molded I can get as I like them the best overall, but it is amazing how close the Xicon caps sound to them.

I do think it is a good idea to operate new builds.  I was on a run building clones of the 63 Vibroverb for a few guys.  If I do make an amp for someone I will take the time to break-in everything for about 3 days.  I normally use Black Sabbath.    Serious.

Interesting tidbit.  I had 2 of the amps I built over at the house a few weeks ago and these amps are exactly the same.  I even made sure the tapped treble pots measured the same.  Same speakers, everything.  Both guys love the amps and the amps sound different, surprisingly different.

What makes the difference is one has a smooth plate Telefunken in V2 and the other has a NOS RCA white letter blackplate from 1957.  All else is the same.  This is probably the largest difference I have heard in 2 amps that are the same.  I put new Gold Lions in the same place in both amps and they sounded almost the same.  That is the first time I really took notice of how much the first tube sounds.

I gusee what I am saying

[jojokeo]

True Brad and you are correct.  I would not recommend doing this to anyone.  It is something I do, but you do not have to have the volume of Hendrix or Santana.  Actually the last one I did I used a pedal Joe made for me.  The frequencies would change..

Sweet! Another use for the Harmonic FungShway! (good news on this - I found a big supply of the vintage parts needed, so there is plenty to build many more and even lower the cost a bit too).
 

If I do make an amp for someone I will take the time to break-in everything for about 3 days.  I normally use Black Sabbath.    Serious.

Don't tell Richie/Jimbo - he'll get jealous you don't use Purple Rain...err Deep Purple.
 

Interesting tidbit.  I had 2 of the amps I built over at the house a few weeks ago and these amps are exactly the same.  I even made sure the tapped treble pots measured the same.  Same speakers, everything.  Both guys love the amps and the amps sound different, surprisingly different.

What makes the difference is one has a smooth plate Telefunken in V2 and the other has a NOS RCA white letter blackplate from 1957.  All else is the same.  This is probably the largest difference I have heard in 2 amps that are the same.  I put new Gold Lions in the same place in both amps and they sounded almost the same.  That is the first time I really took notice of how much the first tube sounds.

Which did you prefer outta those? Or how best would you describe the differences attributed to each?
 
I was just telling Jim I have different amps where a certain tube sounds better but maybe not in a diferent amp. Meaning that one tube does not fit all? I have a new reissue Mullard that sounds better in my SE EL34 amp, then a NOS Sylvania that sounds great in V1 of my Tweed Super, and yet an RCA w/ the flat sided spacer in another, and good ol' ampere/Holland is also always good. But for reliability I'll use a new Tung Sol in my gigging Sheriff amp...
 
Which leads to this original post/question - I just finished a 2nd DumbleWatt 2.0 for a recording studio guy/friend. I only played it last night for the first time at about 10pm so tonight will be a good test but I don't have all identical tubes unless maybe I do some "tube robbing" from a few horses in the stable?

[HotBluePlates]

Looking for any information regarding "burning-in" new amp builds. ... For how long? What does it supposedly do? ...

I've never burned-in any of my amps. I did buy some Scumback speaker where they did a break-in period, but as far as I know (getting them after the break-in) they've always sounded great.


I can tell you a couple reasons others have done burn-ins:

• I briefly worked at a p.c. board manufacturer, and many of their boards had a final test/burn-in before shipping. The boards were already assembled, and had quick-check and functional testing done. So all the boards "worked." However, we're dealing with machine-placed parts and soldering, as well as solid-state electronics. The nature of that beast is that some faults only show up after the parts on the board are hot from use. This might include marginal solder joints that open up, or transistors that have manufacturing defects which cause failures once the part is hot. In general, this manufacturer didn't burn-in every board they made; some products subjected a 5-10% sample of production to burn-in, while others which often had malfunctioning parts (defective from their manufacturer) were subjected to 100% burn-in and testing.
• Newly-made tubes might benefit from a burn-in period. Tomer notes that catastrophic tube failures mostly occur within the first 100 hours of operation, drop to a very low level between 500-1000 hours of use, eventually reaching an extremely low rate of incidence after 5000 hours of use. (Getting the Most Out of Vacuum Tubes, page 8)  RDH4 also notes that tube characteristics drift most during the first 100 hours of life, and that stability can be aided by operating the tube for ~2 days. (RDH4, page 24)

What you should take away from that is that burn-in for tube amps/electronics may be mostly about giving questionable-quality tubes and chance for infant mortality, and for amps to exhibit failures only occurring with heat/use. I'd argue that your use of burn-in periods should be driven more by your awareness and understanding of typical failure modes for whatever you're building than others' claims about how/why to burn-in. I saw first-hand with the board manufacturer that their burn-in policies were directly related to their engineers analyzing acceptance rejects & warranty claims to understand how/when their products tended to fail, and instituting appropriate testing to identify problems... but only on the products shown through experience to be failure-prone. 100% test and burn-in of products shown to be highly reliable in practice would be a waste of time & money (for them and for you).

[jojokeo]

All good points Mr B! I've never intentionally burned-in my amps other than by playing the heck out them especially when new, except every once in a while when something distracts me (phone, wife, dogs, etc.) and I walk away from the amp w/out turning it off first. oops 

I suppose the take away is that amplifier burn-in is more for detecting failures rather than having any sonic benefits? The term "burn-in" seems inappropriate, something better would be simply "testing phase"? Then if successful the outcome would become the "break-in" period or if unsuccessful the big "burn-out". 

[PRR]

Speakers will loosen-up after first hard work.

Specially rough-and-ready guitar cones.

Hi-Fi speakers less so; but I always ran new music-school classroom speakers with a little hard rock at medium volume (my ears are tuned to the mix-style) then an hour of Bach and Beethoven ranging from medium to thunderous.

Obviously you should run the range of YOUR repertoire, not my school's academic syllabus. (Yes, we also covered Schoenberg and Cage, but I wasn't gonna sit for that.)

[Ed_Chambley]

True Brad and you are correct.  I would not recommend doing this to anyone.  It is something I do, but you do not have to have the volume of Hendrix or Santana.  Actually the last one I did I used a pedal Joe made for me.  The frequencies would change..

Sweet! Another use for the Harmonic FungShway! (good news on this - I found a big supply of the vintage parts needed, so there is plenty to build many more and even lower the cost a bit too).
 

If I do make an amp for someone I will take the time to break-in everything for about 3 days.  I normally use Black Sabbath.    Serious.

Don't tell Richie/Jimbo - he'll get jealous you don't use Purple Rain...err Deep Purple.
 

Interesting tidbit.  I had 2 of the amps I built over at the house a few weeks ago and these amps are exactly the same.  I even made sure the tapped treble pots measured the same.  Same speakers, everything.  Both guys love the amps and the amps sound different, surprisingly different.

What makes the difference is one has a smooth plate Telefunken in V2 and the other has a NOS RCA white letter blackplate from 1957.  All else is the same.  This is probably the largest difference I have heard in 2 amps that are the same.  I put new Gold Lions in the same place in both amps and they sounded almost the same.  That is the first time I really took notice of how much the first tube sounds.

Which did you prefer outta those? Or how best would you describe the differences attributed to each?
 
I was just telling Jim I have different amps where a certain tube sounds better but maybe not in a diferent amp. Meaning that one tube does not fit all? I have a new reissue Mullard that sounds better in my SE EL34 amp, then a NOS Sylvania that sounds great in V1 of my Tweed Super, and yet an RCA w/ the flat sided spacer in another, and good ol' ampere/Holland is also always good. But for reliability I'll use a new Tung Sol in my gigging Sheriff amp...
 
Which leads to this original post/question - I just finished a 2nd DumbleWatt 2.0 for a recording studio guy/friend. I only played it last night for the first time at about 10pm so tonight will be a good test but I don't have all identical tubes unless maybe I do some "tube robbing" from a few horses in the stable?

I prefer the RCA, but it has more color and tends to have fuzziness the Gold Lions are very similar to the Telefunken.  The major difference is touch.  The Telefunken does not respond as well or as easily to being pushed.  I normally use the Smooth Plate Telefunken in my Super Reverbs for clean and spanky.  The Gold Lions are the same but do overdrive.

Not being a fan of 12Ax7 distortion, i prefer a tube that has the 'hair' of the old RCA which I do not find in the Gray Plate.  The Black Plate RCA I use in Brownface and prefer them.  They are the dirty girl of the bunch.  The also work well in JTM45.  I still prefer 12Ay7 in tweeds.  What is strange is I have never used anything but RCA 12Ay7.

Yes, the FuzzSway will actually feedback different notes and if you do a double stop and let it feedback, you can then wiggle the string that is not feeding back and it will change to it. That is if you can do a vibrato on one string while holding the other steady.  Gotta use your fingers you know.  The wrist or forearm vibrato is too wide.  And the insane SRV vibrato, forget about it.

[HotBluePlates]

I prefer the RCA, but it has more color and tends to have fuzziness the Gold Lions are very similar to the Telefunken.  The major difference is touch.  The Telefunken does not respond as well or as easily to being pushed.  I normally use the Smooth Plate Telefunken in my Super Reverbs for clean and spanky.  The Gold Lions are the same but do overdrive.

Opinion time: I have a fair number of Telefunken ECC83's, and have used them in amps and mic preamps.

The overall impression I get is that Telefunkens are smooth and neutral; good tube for clean and when you desire very flat frequency response. All other tubes seem to have "color" of some kind. Each in its own direction and amount, whether good or bad.

Whatever color exists probably work well in some amp for some application. Agreed that swapping the first preamp tube or 2 will have the biggest impact on an amp's sound of any tube swap. Feedback, either around a phase inverter/output stage or around portions of a preamp (as in some mic preamps) will/should nullify the impact of a tube swap. Along with reducing distortion, the feedback will reduce/eliminate variations in performance due to changes in a tube's characteristics over time (or in the event of a swap). It will do this until the tube is so worn out its Gm is too low to support the amount of feedback.

[Fresh_Start]

I've always "burned in" speakers and amp with Hendrix.  Test voltages and everything else before and after.  I'm 99% sure that I've always heard a difference, usually smoother and sweeter sound. I always attributed the sound change to the speaker. Never thought about tubes changing sound/tone. Don't have a big stash of old tubes, so I need to use new ones mostly. Had a couple of new 12AT7s go bad  (sequentially) very quickly in one AB763 build.

I had a digital scale that went flaky on me after leaving it on overnight. Cheap Chinese electronics. Fortunately the U.S. "Manufacturer" replaced it with no hassle. Second one works well.

Back in the early days of PCs, it always was wise to leave it on for a day or two out of the box because that was the most likely time for a failure.

Bottom line, if electrons move around inside, I assume it will fail in the first 20-50 hours or be good to go for a long time.

Cheers,

Chip


P.S. First preamp tube and power tubes seem to make the most difference in tone. I had some JJ El84s that I absolutely hated in my Blues Jr.  Was fixing up a cheap Peavey for a friend and thought "Can't hurt, let's try them here".  I'd already tried 2 or three sets of power tubes but those JJs were perfect for that amp. Go figure.

[Ken Moon]

I don't build amps in high quantities, but every amp I build is tweaked to the buyer's taste.

When I finally get done and I invite him over to try the final product, they always want to take it with them when they leave.

I've suggested that they leave the amp on overnight in case one of the tubes goes bad, but I don't know if anyone's ever done it!