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Post by leonski on Aug 31, 2018 15:14:36 GMT -5
I heard what I heard. No mistake. I touched Nothing to 'fix'. It has never recurred.
Capacitor forming is a KNOWN characteristic of caps. Just plug in an amp which has SAT for 5 years or more and watch the PS caps self-destruct.
Bring it up on a Variac to 'reform' the caps and you'll probably be fine. Just takes time. I know the Aluma paste is different than Mylar or Polyester or whatever is the dielectric in other caps.
As for speakers breaking in MECHANICALLY? Sure, why not? I sent some MG1 panels to Magnepan for repair. They were subtly different upon return.
'd' amps use smaller caps. Will they be effected more or less than some of the larger values? I don't know. And if they are effected, if they are PS and not directly in the signal path? Again, I don't know.
Other break-in theories include thoughts about dielectric (insulator) saturation and other phenom.
I have an idea to test one of these which with the stuff at EMOs shop would take less than an afternoon, the use of a signal generator and a scope......along with a few 'misc' parts for test and compare.
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Post by jimk1963 on Aug 31, 2018 16:51:18 GMT -5
Please report back your observations of that setup. I also have an A3050 and am considering a trio of PA-1s for the LCR speakers. Would be very curious to hear your results. Will do. Amps are in CA, scheduled for delivery tomorrow. May or may not have time to get them connected this weekend.. Reminds me, another "thing" that I see talked about endlessly but as a EE I'm so skeptical of - "burning in" these modern solid state amps. A smattering of Class D reviews out there claim that the amps sounded cold/sterile/"hard edged" until some random burn-in period. Some say 24 hours, one guy claimed 100 hours was needed. For me, there has to be clear science around this, and I just don't see it, with one exception - noisy capacitors. I've literally heard certain capacitor types sing (piezoelectric effect) over the years of designing cellular radios, but past that it's hard to imagine solid state circuits changing their characteristics after a short run-in. I'm open to be enlightened, please have at it. I'm sure there are golden audio best practices that include selection of high quality components to avoid all manner of audible sin. I'm just not fully clear on those techniques I guess. Received 3 Stealth PA-1's today, just connected one unit and... HUUMMMMMMMM. Setup: Yamaha RX-A3050, B&W CWM7.4 in-walls (6 ohm), twin VTF3-MK5 subs, etc. PA-1 connected to Front Left out via 3 methods: (1) Emotiva RCA-1/4" adapter + shielded RCA cable (Monoprice) (2) Hosa GXM-133 RCA to XLR3M Adapter + shielded RCA cable (3) JOLGOO Dual XLR Male to RCA Male Cable. Amp is sitting on top of media cabinet, plugged into a Furman power strip (yes, with other things plugged into that strip). 3-prong connection all the way (wall outlet, Furman, Amp). In Case (1), no sound at all. The 1/4" adapter is crap, does not work. No HUM regardless of AUTO/ON switch position --> which means either + or - or both are physically not connected. Case (2), major hum when AUTO/ON switch is set to ON, sound works. No sound at all when set to AUTO, regardless of audio level. By major, I mean you can hear the hum from the next room. Case (3), same as Case (2). Arguably a very slight improvement in HUM volume, nothing meaningful. Moved the amp around over a 2 foot space, including out of the cabinet altogether (it's now sitting on top as noted), to see if something is radiating (coupling) into the amp. No meaningful change in HUM. This is among the poorest OOB experiences I've had with audio gear of any price. Very disappointing. Called main line, the company is off to a San Diego trade show, so had to leave a VM. Have owned maybe half-dozen amps over the years, have had HUM issues only once - a subwoofer amp (Paradigm Servo 15 v2). Will try a few things (2-prong 110VAC connection, a different wall outlet, whatever else I can think of), I've already swapped a few cables to make sure they aren't the issue. Seriously bummed. |
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Post by leonski on Aug 31, 2018 18:30:07 GMT -5
Does the monoprice 'shielded' cable connect the shield at BOTH ends or just the end that 'feeds' the signal?
Is the TV on during this testing?
If ALL THREE amps behave identically, than it would a different call than if only 1 of the amps has such a hum.
Shut off EVERYTHING. Caonnect amp to speaker. Turn on. Than? Add connection back to preamp.
some kind of troubleshooting procedure like that may yield a result.
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Post by jimk1963 on Aug 31, 2018 22:37:43 GMT -5
Does the monoprice 'shielded' cable connect the shield at BOTH ends or just the end that 'feeds' the signal? Is the TV on during this testing? If ALL THREE amps behave identically, than it would a different call than if only 1 of the amps has such a hum. Shut off EVERYTHING. Caonnect amp to speaker. Turn on. Than? Add connection back to preamp. some kind of troubleshooting procedure like that may yield a result. Thanks much for the thought experiments, good stuff. Hum on all 3 amps. Monoprice cable is shielded on both ends. Hum is only present if connected to Yamaha pre-out. Conclusion - ground loop somewhere in the system. Pulled out my 3-to-2 AC adapters to verify, sure enough - they eliminated hum on all 3 amps. PA-1's ship with a 3-prong power cord - I'm assuming/hoping there's no shock hazard by floating the earth ground with the 3-2 adapter. Do not like having to go this route, but for now the hum is 100% eliminated. Re: the 1/4"-to-RCA adapters, all 3 are bad. No signal at all. Emotiva completely dropped the ball on this - how the bleep did they actually test these amps and adapters and miss this?? Watched TV tonight with the 3 amps, nothing intense - some football and a series "Sinners", mostly dialogue and background music. So not much to say about sound quality, other than it did seem like more of the finer (delicate) sounds were very audible whereas not so much with the Yamaha alone. For example, the sound of leaves blowing, echo when people are talking in a big space, things like that. When I have more time I'll do more careful A/B comparisons, but my initial impression is good. Amps are basically at room temp after about 5-6 hours of running, Yamaha is definitely running cooler too (expected of course). This was part of my grand scheme - with a new built-in cabinet coming, wife-friendly ventilation is a challenge so thought I'd give Class D a fair chance. So far, so good - other than the awful issue with hum. I will diagnose the hum issue further in the next couple of weeks when I have time to dig in. |
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Post by leonski on Aug 31, 2018 23:52:43 GMT -5
When researching DIY power cords, I came across a VERY popular build using Belden 19364 which is a 14ga power cable. It is the regular 3 wires, hot/ neutral/ ground AND a foil shielf over the works. All the DIYs I read said to connect the shield ONLY at the
outlet end. Not the end plugging into the component.
RCA, or 'single ended' is only a 2 wire system. Information is +- and a ground. If this cord is grounded where is the ground? It SHOULD only connect to the ground wire at ONE end, IMO. If the MONOPrice were connected shield to ground at only ONE end, the cable
might be considered 'directional' and swapping ends might give a result.
If you have an UNShielded cable, even one of the Throw Aways that came with something, give that one a try.
Keith made some comments about the Balanced / Single Ended adaptor. You may want to get in touch w/EMO and get that straightened out. It's essentially a SIMPLE device and it a batch were mis-wired, I'd be surprised. That wouldn't be something
I'd normally spend a lot of time 'checking'.
As for your 3-2 AC cheater plugs? With that connected and working, find a buddy with a DVM and check for voltage from CHASSIS to CHASSIS of the Yamaha to one of the PA-1s.
Is there a SAT Dish or CABLE receiver anywhere in this mix?
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Post by jimk1963 on Sept 1, 2018 11:10:39 GMT -5
When researching DIY power cords, I came across a VERY popular build using Belden 19364 which is a 14ga power cable. It is the regular 3 wires, hot/ neutral/ ground AND a foil shielf over the works. All the DIYs I read said to connect the shield ONLY at the outlet end. Not the end plugging into the component. RCA, or 'single ended' is only a 2 wire system. Information is +- and a ground. If this cord is grounded where is the ground? It SHOULD only connect to the ground wire at ONE end, IMO. If the MONOPrice were connected shield to ground at only ONE end, the cable might be considered 'directional' and swapping ends might give a result. If you have an UNShielded cable, even one of the Throw Aways that came with something, give that one a try. Keith made some comments about the Balanced / Single Ended adaptor. You may want to get in touch w/EMO and get that straightened out. It's essentially a SIMPLE device and it a batch were mis-wired, I'd be surprised. That wouldn't be something I'd normally spend a lot of time 'checking'. As for your 3-2 AC cheater plugs? With that connected and working, find a buddy with a DVM and check for voltage from CHASSIS to CHASSIS of the Yamaha to one of the PA-1s. Is there a SAT Dish or CABLE receiver anywhere in this mix? Great inputs, thanks. Hum occurred not only with Monoprice cable but also with the all-in-one cable with RCA on one end, XLR on the other. You make a good point about shielded ground on both sides vs one side, will have to check that. Will also be looking at chassis voltages, and yes DirecTV is in the mix. All devices are connected through a Panamax 5400EX; the Furman strip I mentioned earlier plugs into the Panamax. I will revisit that setup as well. Played some music last night, only briefly, right away was impressed with clarity of sound. I haven’t recalibrated the system yet but at present settings these little amps don’t seem to drive the speakers any harder (louder) than the built-in Yamaha amps. This is one of the key things I will be evaluating, e.g., what does a ~200W Class D amp really do. I expect it to easily surpass SPL of the Yamaha. If not, this will reduce the value proposition. |
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Post by lcheetec on Sept 1, 2018 11:12:37 GMT -5
Used some cheaters, and my hiss is gone... finally. Thanks for the suggestions. Daniel  |
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Post by leonski on Sept 1, 2018 16:32:38 GMT -5
When researching DIY power cords, I came across a VERY popular build using Belden 19364 which is a 14ga power cable. It is the regular 3 wires, hot/ neutral/ ground AND a foil shielf over the works. All the DIYs I read said to connect the shield ONLY at the outlet end. Not the end plugging into the component. RCA, or 'single ended' is only a 2 wire system. Information is +- and a ground. If this cord is grounded where is the ground? It SHOULD only connect to the ground wire at ONE end, IMO. If the MONOPrice were connected shield to ground at only ONE end, the cable might be considered 'directional' and swapping ends might give a result. If you have an UNShielded cable, even one of the Throw Aways that came with something, give that one a try. Keith made some comments about the Balanced / Single Ended adaptor. You may want to get in touch w/EMO and get that straightened out. It's essentially a SIMPLE device and it a batch were mis-wired, I'd be surprised. That wouldn't be something I'd normally spend a lot of time 'checking'. As for your 3-2 AC cheater plugs? With that connected and working, find a buddy with a DVM and check for voltage from CHASSIS to CHASSIS of the Yamaha to one of the PA-1s. Is there a SAT Dish or CABLE receiver anywhere in this mix? Great inputs, thanks. Hum occurred not only with Monoprice cable but also with the all-in-one cable with RCA on one end, XLR on the other. You make a good point about shielded ground on both sides vs one side, will have to check that. Will also be looking at chassis voltages, and yes DirecTV is in the mix. All devices are connected through a Panamax 5400EX; the Furman strip I mentioned earlier plugs into the Panamax. I will revisit that setup as well. Played some music last night, only briefly, right away was impressed with clarity of sound. I haven’t recalibrated the system yet but at present settings these little amps don’t seem to drive the speakers any harder (louder) than the built-in Yamaha amps. This is one of the key things I will be evaluating, e.g., what does a ~200W Class D amp really do. I expect it to easily surpass SPL of the Yamaha. If not, this will reduce the value proposition. What is the power of the Yamaha? IF the new amp is 2x the power, you can expect 3db increase in test tone loudness. Now you get into dynamic power. Since you are unlikely to EVER use even 1/2 the RMS power of an amp, you are worried about dynmic power. For example: You are cruising along at 3 watts per speaker. That with 90db speakers is pretty loud. That would be 2 speakers and IN ROOM. 10db peaks also happens to be 10x the POWER. So that turns into 30 watt peaks. So far? The Yammy and the PA-1 should both be keeping up. 30 watts to 120 watts turns into 16db peak. Most movies or music should be in the neighborhood of 20db? Those 20db peaks will run 100x the power of 'steady state'. Figuring power used is tricky. You have the sensitivity of the speaker to consider. Than since it's a PAIR you add. Than you need to know if the speaker builder rated his speaker In-Room or AnaChoic (sound proof room with NO echo, basically) which LOWERS the apparent number. Than, since your room 'bounces' a lot of sound you add some MORE to the basic single speaker number.(room gain) Than subtract for sitting maybe 10 feet from the speakers. (3 meters?) Those calculations are if you really want to go nuts. I gave up long ago. As it turns out, you are replacing one amp with another. So everything else remains equal. I wouldn't expect the new amps to be more than 2 or 3 db louder than the Yammy, but clearer with less distortion when pressed. Experiment some more but realize the general rule that it takes 2x the power to make a reasonable difference. And I also don't really like most amps in HT gear. They might rate them as 120 watts but that's with 2 channels driven. Add 3 or 5 more channels and you are down to 80 watts and distortion both rises and the amp is less than capable into 4 ohm speakers. Even an 8-ohm rated speaker is likely to drop to under 5 ohms or so at some point in its range. That's why HT speakers are generally 8 ohms, less frequently 6 ohms and almost always a 'moderate' to 'easy' load for the partnering amp. How LOUD do you really want it? |
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Post by leonski on Sept 1, 2018 18:36:58 GMT -5
I find it a little odd that Yamaha quotes 8 ohm power at 2 distorions, but that's OK.
No mention of anything BUT 8 ohm power and certainly NOT with more than 2 channels driven.
The 'Gold Standard' for amps is to DOUBLE the power when going from 8 ohms to 4 ohms. Few amps actually DO that, and some rely on specsmanship to reach that goal.
The Yamaha might actually put out more power into 4 ohms than 8, but probably NOT. They'd brag about it if it DID. And runing 5 channels or more @8? Power will drop like a stone.
OFFLOADING power demands from the Receiver to the outboard amps is a good thing, and will help the Yamaha last longer and run cooler.
The PA-1 actually has fractionally LESS power than the Yammy. But since the PA-1 calls out 4 ohm power, it might actuallly be more capable into a 'real' speaker load.
To play louder, you 'll need DOUBLE the power of the Yammy to start, more being better OR you can find more sensitive speakers you like as well, that make better use of available power.
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wvs007
Seeker Of Truth
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Post by wvs007 on Sept 2, 2018 21:09:26 GMT -5
Received my mono blocks last week. I have to confess, just "out of the box" they almost went back into the box immediately! I have been running them for a few days now listening and just random music playing. After 20 hours they became more mature and yesterday after about 30+ hours the quality starts kicking in with good recordings now sound much better. The only concern is that the one led died after a day but I actually prefer no lights...especially as this blue is a bit different from the DC-1. Attachments:
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Post by AudioHTIT on Sept 9, 2018 13:07:01 GMT -5
Was about to order the PA-1’s to try on my Maggies, but forgot about no trigger, that and no power switch might make it a no go for me.
My XMC-1 drives my HT and 2C Systems, the L/R outputs feed two sets of amps, what plays is simply determined by which amps are on. When I’m listening to HT the trigger output turns on the HT amp, the 2C amps are powered off. When I listen to Stereo the triggers stay off and I manually power on the VTLs with the front panel switch. Works fine for me.
I was thinking I could make it even better with triggers on the 2C amps as well, but without them or power switches I won’t be able to turn the PA-1’s off; if they’re on, sound will come out of the Maggie’s even when I don’t want it.
I’ve gone to a bit of trouble to route power carefully in the new Credenza and I’m not open to triggered power strips.
... hmmm, one nice thing about writing is it makes you think things through, just had an idea. I could replace the duplex plugs mounted for those amps with ZWave modules that the Harmony Hub could power on and off, have to ponder that.
Any other ideas?
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Post by garbulky on Sept 9, 2018 15:23:05 GMT -5
Was about to order the PA-1’s to try on my Maggies, but forgot about no trigger, that and no power switch might make it a no go for me. My XMC-1 drives my HT and 2C Systems, the L/R outputs feed two sets of amps, what plays is simply determined by which amps are on. When I’m listening to HT the trigger output turns on the HT amp, the 2C amps are powered off. When I listen to Stereo the triggers stay off and I manually power on the VTLs with the front panel switch. Works fine for me. I was thinking I could make it even better with triggers on the 2C amps as well, but without them or power switches I won’t be able to turn the PA-1’s off; if they’re on, sound will come out of the Maggie’s even when I don’t want it. I’ve gone to a bit of trouble to route power carefully in the new Credenza and I’m not open to triggered power strips. ... hmmm, one nice thing about writing is it makes you think things through, just had an idea. I could replace the duplex plugs mounted for those amps with ZWave modules that the Harmony Hub could power on and off, have to ponder that. Any other ideas? OH that's easy. I assume the PA-1 amps work this way. Get a smart switch. Like this one. www.amazon.com/Kasa-Smart-Wi-Fi-Plug-TP-Link/dp/B0178IC734/The idea would be to leave the amps turned on. Then turn it on and off by turning off and on the smart switch. You could buy an echo dot which you can buy used for $30. Then all you say is "Alexa turn off/on the amp" and then it will turn the smart switch off/on. I would check with emotiva to see if this would work, but I beleve it will. But fwiw, since it is class D the amp probably consumes very little power when turned on. Likely a watt. |
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Post by AudioHTIT on Sept 10, 2018 1:35:24 GMT -5
Was about to order the PA-1’s to try on my Maggies, but forgot about no trigger, that and no power switch might make it a no go for me. My XMC-1 drives my HT and 2C Systems, the L/R outputs feed two sets of amps, what plays is simply determined by which amps are on. When I’m listening to HT the trigger output turns on the HT amp, the 2C amps are powered off. When I listen to Stereo the triggers stay off and I manually power on the VTLs with the front panel switch. Works fine for me. I was thinking I could make it even better with triggers on the 2C amps as well, but without them or power switches I won’t be able to turn the PA-1’s off; if they’re on, sound will come out of the Maggie’s even when I don’t want it. I’ve gone to a bit of trouble to route power carefully in the new Credenza and I’m not open to triggered power strips. ... hmmm, one nice thing about writing is it makes you think things through, just had an idea. I could replace the duplex plugs mounted for those amps with ZWave modules that the Harmony Hub could power on and off, have to ponder that. Any other ideas? OH that's easy. I assume the PA-1 amps work this way. Get a smart switch. Like this one. www.amazon.com/Kasa-Smart-Wi-Fi-Plug-TP-Link/dp/B0178IC734/The idea would be to leave the amps turned on. Then turn it on and off by turning off and on the smart switch. You could buy an echo dot which you can buy used for $30. Then all you say is "Alexa turn off/on the amp" and then it will turn the smart switch off/on. I would check with emotiva to see if this would work, but I beleve it will. But fwiw, since it is class D the amp probably consumes very little power when turned on. Likely a watt. Thanks Garbulky, those are similar to the ZWave Outlets I alluded to above and like the ones I use on my landscape lights (also ZWave). Instead of a module plugging into an outlet, I would replace the outlet with one that’s ZWave controlled and compatible with the Harmony Hub instead of Alexa. However, I need 4 plugs because if a pair of PA-1’s work out, I may get a second pair and bi-amp. Unfortunately all of the outlets seem to have only one controlled plug and one always on. It would take about $150 in plugs and new boxes for that solution. So I’ve found another option by means of an AVS thread, this triggered plug strip (I said I didn’t want) could replace my 2 outlet boxes in the Power Amp cubbies. www.amazon.com/gp/product/B00WV7GMA2/ref=ox_sc_act_title_1?smid=A1MAXJIALWUXGM&psc=1The nice thing is it will cleanly mount in the same place as my duplex outlet and be fed from an existing power line, additionally it has (2) normally off outlets, (1) normally on outlet, and (1) always on outlet. So now I can again use a trigger signal from the XMC-1 to power on/off (4) outlets (between the 2 boxes), and with them the PA-1s (in always on mode). The only drawback is that it each box may be limited to 12 amps total, they list that for a 16 AWG feed. Mine is a 12 AWG / 20A feed, but its internals won’t handle that (though it might do 15A). I’d still have 20 Amp total between the two boxes, and the PA-1’s max draw is likely less than 5 Amps so I should be fine with 4 of them, or more. So I ordered one of them for each power cubbie, they look like cool devices. I’m pretty ingrained with the Harmony Hub, besides the remote capabilities for all my HT/2C gear, it does lights, outlets, locks, scheduling, thermostats, smoke detectors, etc.—same things Alexa does I’m sure, but just been around longer (and I don’t have to worry about Siri getting jealous). |
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KeithL
Administrator 
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Post by KeithL on Sept 10, 2018 9:25:02 GMT -5
You mention "needing four controlled outlets".
How about just plugging a simple "stupid" power strip into the one controlled outlet? (You don't need four independently controlled outlets.)
OH that's easy. I assume the PA-1 amps work this way. Get a smart switch. Like this one. www.amazon.com/Kasa-Smart-Wi-Fi-Plug-TP-Link/dp/B0178IC734/The idea would be to leave the amps turned on. Then turn it on and off by turning off and on the smart switch. You could buy an echo dot which you can buy used for $30. Then all you say is "Alexa turn off/on the amp" and then it will turn the smart switch off/on. I would check with emotiva to see if this would work, but I beleve it will. But fwiw, since it is class D the amp probably consumes very little power when turned on. Likely a watt. Thanks Garbulky, those are similar to the ZWave Outlets I alluded to above and like the ones I use on my landscape lights (also ZWave). Instead of a module plugging into an outlet, I would replace the outlet with one that’s ZWave controlled and compatible with the Harmony Hub instead of Alexa. However, I need 4 plugs because if a pair of PA-1’s work out, I may get a second pair and bi-amp. Unfortunately all of the outlets seem to have only one controlled plug and one always on. It would take about $150 in plugs and new boxes for that solution. So I’ve found another option by means of an AVS thread, this triggered plug strip (I said I didn’t want) could replace my 2 outlet boxes in the Power Amp cubbies. www.amazon.com/gp/product/B00WV7GMA2/ref=ox_sc_act_title_1?smid=A1MAXJIALWUXGM&psc=1The nice thing is it will cleanly mount in the same place as my duplex outlet and be fed from an existing power line, additionally it has (2) normally off outlets, (1) normally on outlet, and (1) always on outlet. So now I can again use a trigger signal from the XMC-1 to power on/off (4) outlets (between the 2 boxes), and with them the PA-1s (in always on mode). The only drawback is that it each box may be limited to 12 amps total, they list that for a 16 AWG feed. Mine is a 12 AWG / 20A feed, but its internals won’t handle that (though it might do 15A). I’d still have 20 Amp total between the two boxes, and the PA-1’s max draw is likely less than 5 Amps so I should be fine with 4 of them, or more. So I ordered one of them for each power cubbie, they look like cool devices. I’m pretty ingrained with the Harmony Hub, besides the remote capabilities for all my HT/2C gear, it does lights, outlets, locks, scheduling, thermostats, smoke detectors, etc.—same things Alexa does I’m sure, but just been around longer (and I don’t have to worry about Siri getting jealous). |
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Post by donh50 on Sept 10, 2018 9:45:38 GMT -5
Capacitor "forming" is rarely if ever audible, particularly for speakers. However, the Magnepan panels do change over the first few hours of use as the plastic sheets break in. Magnepan is clear about that, or used to be, and many years ago I measured the break in on a new pair of Maggies (Mg-II's or MG-III's, I think). As you'd expect it was a steep curve for the first few minutes and mostly done after an hour or so, with smaller changes through perhaps 10 hours. IIRC there was no significant change from 10 to 100 hours (at which point I stopped measuring). The changes were mostly in the bass; midrange and treble changes were much more subtle and with the equipment I had at the time I'm not sure I would swear they were out of the noise floor after the first few minutes. The bass response definitely dropped 5-10 Hz but was low enough it wasn't audible.
For conventional speakers, break-in happened in seconds and was inaudible for all practical purposes.
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KeithL
Administrator
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Post by KeithL on Sept 10, 2018 10:18:27 GMT -5
Capacitor forming occurs when a capacitor that's been sitting for a long time becomes leaky due to "time changes" in the electrolyte and other internal components. Some capacitors have the ability to "self heal" if this happens - and will do so if power is applied slowly to them.
This was observed frequently with tube amplifiers - but is rather uncommon with the types and values of capacitors used in modern equipment. In general, modern amplifier designs (not tubes) avoid capacitors in the signal path, and, if they do have one or two, they are operating at a relatively low voltage.
Many service people still "bring the voltage up slowly" on an amp that's been sitting for a long time. However, with solid state amps, the reason is usually more to minimize the damage if parts fail than to "give the caps a chance to warp in". (By bringing the voltage up slowly, if an output device or a cap is shorted, you'll find out before it draws a destructive amount of current, which may avoid a cascading failure.)
The biggest change in operating point you're likely to see with modern amplifiers is due to operating bias current. Many transistors, especially large power transistors, have an operating point that shifts significantly with temperature. With most Class A/B amps, including ours, the bias current adjusts automatically as they warm up, and may be significantly different when "warm" than when "cold". This is one reason why bias adjustments are always done "after a good half hour warm-up". And, yes, sometimes the difference in bias current will be audible.
However, this phenomenon is temperature-related - so it happens every time the amp warms up and cools down.
Class-D amps are quite a different animal... and the old rules no longer apply. If anything, with a Class-D amp, any differences you might notice are FAR mor likely to be due to thermal "warm-up" than to any sort of "burn-in".
For example, while certain components carry a voltage that is proportional to the line voltage, others carry an amount of current that is the inverse. Many parts in a typical Class-D amp are asked to deliver more current, and so run hotter, and under more stress, at LOWER supply voltages, and many only operate at all over a specific narrow operating voltage range. This means that, if you try to increase the line voltage to a Class D amp gradually with a Variac, it may not work properly at all, and may even be damaged. Also, because most of the capacitors used in Class-D circuitry are involved with high-frequency signals, rather than audio signals, they are not operated under the same sort of conditions. I heard what I heard. No mistake. I touched Nothing to 'fix'. It has never recurred. Capacitor forming is a KNOWN characteristic of caps. Just plug in an amp which has SAT for 5 years or more and watch the PS caps self-destruct. Bring it up on a Variac to 'reform' the caps and you'll probably be fine. Just takes time. I know the Aluma paste is different than Mylar or Polyester or whatever is the dielectric in other caps. As for speakers breaking in MECHANICALLY? Sure, why not? I sent some MG1 panels to Magnepan for repair. They were subtly different upon return. 'd' amps use smaller caps. Will they be effected more or less than some of the larger values? I don't know. And if they are effected, if they are PS and not directly in the signal path? Again, I don't know. Other break-in theories include thoughts about dielectric (insulator) saturation and other phenom. I have an idea to test one of these which with the stuff at EMOs shop would take less than an afternoon, the use of a signal generator and a scope......along with a few 'misc' parts for test and compare. |
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Post by AudioHTIT on Sept 10, 2018 10:35:56 GMT -5
You mention "needing four controlled outlets". How about just plugging a simple "stupid" power strip into the one controlled outlet? (You don't need four independently controlled outlets.) I spent a lot of time designing my cable and power management, I didn’t anticipate an amp that couldn’t be turned off or triggered. As I mentioned above, I don’t want a kludge of cables or power strips and each cubbie has its own outlet. The box I linked can cleanly replace my outlets and give trigger control, it’s even slightly less expensive than most ZWave outlets. I think it’s a pretty cool device and seems the best solution to my problem. |
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Post by leonski on Sept 10, 2018 12:46:32 GMT -5
So, what IS the current draw of a PA-1 when on and in a no-signal condition?
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Post by leonski on Sept 10, 2018 21:18:23 GMT -5
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Post by AudioHTIT on Sept 10, 2018 22:21:19 GMT -5
So, what IS the current draw of a PA-1 when on and in a no-signal condition? I’ll have one to measure on Monday. |
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