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Post by leonski on Jul 8, 2018 17:25:04 GMT -5
leonski, novisnick, garbulky Is there a problem running the XPA-1 on a 15 amp circuit? Did not get an owner's manual for the device and nothing on the website suggests it must be run on 20 amps. Can running the amp on a 15 amp circuit cause extra heat? Have switched my units to A/B and connected them individually to the wall outlets with heavy gauge Pangea cable to see if that helps the heat buildup. Novisnick: thanks for the Aircom recco. Some of the reviews, however, suggest that the unit is noisy. Have you heard one? Thanks all. IMO, buying a PAIR of amps which together are beyond the capability of a 15 amp service, (simple VA call-out of transformer) and than expecting 'all that power' is nutty. Yes, you should still have 'burst' power. Until the caps voltage drops and the PS stresses to 'top them up'. Not to forget that the caps ONLY recharge during that part of the AC cycle where the voltage is above that of the cap. When the caps are fully charged, the PS should only add juice to the caps for the BRIEFEST amount of time when the voltage is at its peak. At all other times, the amp is cruising. It always cracks me up when people talk about 'difficult to drive speakers' as if were an impedance issue only. In this case, Reactance Rules. In short? SURE, it's gonna run. But do NOT expect what you paid for in terms of power output. At least 'long term' which is anything over maybe 1 second or so. Get the amps OUT OF THE OVEN. An amp stand behind EACH speaker might work better. That's what I'm doing. And blowing a fan across the top? Actually may RESTRICT airflow by not allowing the natural CONVECTION up and 'out' due to heating / density. A true 'A' amp will be extraordinarily low efficiency. And it is ALL HEAT. Even those high bias designs by the likes of Pass and Parasound (JC-1) will weigh a lot and run warm virtually ALL the time. If you are in the least interested in some DIY, the NOCTUA fan is on the 'quietest fan' list for sure. |
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Post by DavidR on Jul 8, 2018 18:51:49 GMT -5
Thanks, guys. Class A/B didn't last very long. For the dense orchestral music I listen to, there is a BIG difference between A and A/B. Know this isn't the normal perspective, but the difference in string and timbral accuracy is like night and day for my system and ears. Got a computer radiator fan that is inaudible and pulls 40CFM and am placing it on top of the XPA-1 (middle) and seeing if it brings down the temp comfortably. So far, so good. Am missing the line conditioning of the Furman on the amps because the electricity is very dirty in this particular town. Still, with class A operative, all sounds acceptable and like the idea of having the amps connected directly to the wall outlets. Thanks again. Your knowledge is what makes these threads work. The CMX2 and 6 work well. I wish they were rated for 20 amps thou. |
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Post by milt99 on Jul 8, 2018 20:22:38 GMT -5
leonski, novisnick, garbulky Is there a problem running the XPA-1 on a 15 amp circuit? Did not get an owner's manual for the device and nothing on the website suggests it must be run on 20 amps. Can running the amp on a 15 amp circuit cause extra heat? Have switched my units to A/B and connected them individually to the wall outlets with heavy gauge Pangea cable to see if that helps the heat buildup. Novisnick: thanks for the Aircom recco. Some of the reviews, however, suggest that the unit is noisy. Have you heard one? Thanks all. The XPA-1s running in Class A mode are going to run hot no matter what the amperage of the circuit is. It's just their nature. You didn't say if other devices are running on the same circuit. Beyond the obvious of running a vacuum, especially if you have lamps plugged into that same circuit they will induce undesirable affects. Not necessarily sucking extra power but lamps oscillate at a certain frequency. At the least, switch to Class A\B when not listening, that will cut the heat output exponentially. In reality a 15 amp circuit will only affect the amps during high demand situations. Transients etc. The amps should have sufficient capacitance to supply the almost instantaneous demand. I'm guessing a dedicated 15amp circuit will work fine but in my case the difference between running a dedicated 15amp and 20amp circuit is minimal. Although maybe considered over kill, running dedicated circuits in my theater\music room and in my living room when the end point was more than a single outlet, I split the romex and ran the wire directly to the each outlet rather than in a daisy chain from one outlet to the next. Highly recommend Hubbell Pro-Grade outlets. Nothing exotic just very well made with solid contacts. I managed a computer data center & got great advice from the electronics company that installed and maintained our gear. 2 of the best things they ingrained to me was over wire and under breaker. Buy Hubbell and Square-D pro-grade components. |
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Post by leonski on Jul 8, 2018 20:50:39 GMT -5
Yes, you could even run a 10kw amp on a 15 amp circuit, but WHY? I see what you mean about demand, but I'm still wondering WHY anyone would buy a pair of huge and power consuming amps than run them at only 50% of their potential?
The 2 XPA-1 on a SINGLE circuit has a total of 2400va of transformer. Even IF it was a purely resistive load, (it certainly isn't!) That's 1/3 over capacity of a 15 amp circuit. Which is not 1800 watts, anyway, but factor in a -20% derate for long time period.
A 20 amp circuit is right on the edge. And than you consider that since it is NOT a resistive load, you must eventually consider Power Factor.
A 15 amp circuit might also effect ReCharge RATE, since large current demands will also SAG the line voltage. Below that which is needed to recharge the caps. People who Bench Test amps for a living will always use a Variac to stabalize the line voltage as the
amp draw increases. Which would ordinarily drop line voltage.
And don't forget that you don't have JUST the amps on such a circuit. TV? Preamp? Source Components? Sub? Lighting? Fan? PopCorn Machine? Computer?
Since we don't know the speakers in question, I'll add that when I had a simple Carver Cube of 200x2 @8, running into a pair of Magnepan MG-1 speakers, I could DIM the houselights in time to the music. Amp was running right to redline and the speakers were NOT
particularly happy. I popped the 1 1/2 amp speaker fuse (mid/high only) more than once. And eventuallyl damaged the speakers.
And I'll go with milt on better components. Good outlets help. Better power cords (at least proper gauge) also help. Good connectors help. This is ONE area where DIY can reap substantial benefits.
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Post by craigl59 on Jul 8, 2018 21:28:47 GMT -5
leonski et al:
You raise an interesting question about the purpose of the XPA-1 and loads.
Am running Double Impacts with a sensitivity of 98db. In this context, 60 watts of pure class A is enough to blow you away. I do not need, nor even want, the 1000 watts. It's the 60 watts of Class A that is perfect for me.
Keep in mind the last 3dbs of power on the amp are between 500 and 1000 watts. Can live without these last 3dbs if 15 amps doesn't allow the amp to reach this exalted height. Am already achieving 115db at 60 watts. That's louder than a plane on the runway...
BUT, NOW, have got each amp on a separate 15 amp wall outlet of its own so each has the full and discrete 15 amps of available amperage. Each uses a Pangea AC9 and whatever the house circuitry can give, it will get to the amp.
AND, have gotten a computer fan on the top of each box blowing up and away so that air is brought up from the bottom of the case through the top. The top stays hot in class A BUT the sides are NOT EVEN WARM. So this appears to be working for keeping the units cool in their current rack. Will let you know as I try out various refinements.
Overall, the amps sound SO MUCH BETTER than my previous XPA-1Ls that I don't worry about amperage as long as it won't harm the amp over time -- which I assume from the above respondents it will not. Your comments about not taking full advantage of the unit's power are correct and I understand them -- but they are no reason not to take advantage of this class A wonder.
And I mention again -- it is very kind of you and the others to help me with this install. Thanks again.
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Post by craigl59 on Jul 8, 2018 21:34:02 GMT -5
milt99:
Yes, overwire and underbreaker -- thank you. Appreciate your informed post.
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Post by leonski on Jul 9, 2018 0:00:13 GMT -5
leonski et al: You raise an interesting question about the purpose of the XPA-1 and loads. Am running Double Impacts with a sensitivity of 98db. In this context, 60 watts of pure class A is enough to blow you away. I do not need, nor even want, the 1000 watts. It's the 60 watts of Class A that is perfect for me. Keep in mind the last 3dbs of power on the amp are between 500 and 1000 watts. Can live without these last 3dbs if 15 amps doesn't allow the amp to reach this exalted height. Am already achieving 115db at 60 watts. That's louder than a plane on the runway... BUT, NOW, have got each amp on a separate 15 amp wall outlet of its own so each has the full and discrete 15 amps of available amperage. Each uses a Pangea AC9 and whatever the house circuitry can give, it will get to the amp. AND, have gotten a computer fan on the top of each box blowing up and away so that air is brought up from the bottom of the case through the top. The top stays hot in class A BUT the sides are NOT EVEN WARM. So this appears to be working for keeping the units cool in their current rack. Will let you know as I try out various refinements. Overall, the amps sound SO MUCH BETTER than my previous XPA-1Ls that I don't worry about amperage as long as it won't harm the amp over time -- which I assume from the above respondents it will not. Your comments about not taking full advantage of the unit's power are correct and I understand them -- but they are no reason not to take advantage of this class A wonder. And I mention again -- it is very kind of you and the others to help me with this install. Thanks again. I think your approach and conclusion are fine. For a few $$ more, (a LOT, actually) I'd consider the Pass XA60.8 amps, used. Reno HiFi will certifiy them and stand behind them. You'll need help to get 'em up a flight of stairs. The pass is SINGLE ENDED class 'A' which means NO crossover distorion as virtually All 'push-pull' amps are subject to. These are Jaw Dropping amps, and in class 'A', available up to a LOT of power. But OH! The final Price! |
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Post by pedrocols on Jul 9, 2018 10:26:17 GMT -5
Great.
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Post by craigl59 on Jul 9, 2018 11:03:14 GMT -5
leonski:
Your comments about SET designs are a central question these days and those over on the Audiogon site (Tekton thread) are constantly expounding the appeal of low watt tube SET amps. The Valvet amps from Germany offer this in SS format and, unlike the Pass amps, are relatively lightweight. They have received rave reviews but I have been unable to find anyone who has actually heard one. The low wattage of these (the E2 gives out 20 watts at 4 ohms) makes them, I speculate, less attractive. Valvet accomplishes this SET goal with a single output transistor which design, I think, Pass is also using in the XA25.
Would love to hear a Pass amp period and the one you mention in particular -- in addition to the new XA25. Am assuming that the 60.8 requires a 20 amp circuit? Think there is a dealer in my winter home city that carries Pass.
For now, will enjoy the XPA-1. Now that it is tuned and stable (heat-wise) can sit back as I did last night and spend 4 hours listening to the favorites. Started this goal for my summer home 4 years ago -- to build a system that would generate orchestral music at concert levels.
Thanks to Emotiva (mostly), RME, and Tekton have now achieved this. Have experimented with going to live orchestral concerts and then coming home and comparing the same on recordings. The fidelity is every bit as good (or better) at home. Know this flies in the face of common belief, but I stand by my experience.
My three keys to success are 1) keep the file in *.wav format from start to end, 2) do all EQ, room, impulse, and filter correction in the virtual, software realm, and 3) keep all amplification (pre and power) in balanced class A.
This works for me and I can now reap the benefits with a pristine soundstage in front of me and a Cavalier Spaniel on the lap.
It's a tough life but someone's got to live it...
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Post by leonski on Jul 9, 2018 12:27:10 GMT -5
SE amps, not necessarily the Triode type, are very desired since they have NO crossover distortion. This occurs when you have 2 transistors (or tubes) in a push / pull configuration EACH of which amplifies 1/2 the signal. Either the 'positive' or 'negative'.
Where the signal goes from plus to minus is the problem.
As Pass points out, air is single ended and push/pull might not be the best way.
Pass lists the IDLE current draw for the 60.8 at 3.3 amps while power draw is 400 watts. Being class 'A' I think that's IT. A pair should be OK on a 15amp service, running without OTHER stuff connected.
I think they go maybe 80lb EACH.
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Post by milt99 on Jul 9, 2018 18:32:57 GMT -5
milt99: Yes, overwire and underbreaker -- thank you. Appreciate your informed post. I hope you don't think I was being a smart ass. Just sharing info. BTW, UPS did show up today, minus 1 of the amps. GAWD! Supposedly it's on another truck and will be delivered later today. Why they would split up 2 heavy items like this seems very odd to me. |
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Post by craigl59 on Jul 9, 2018 19:19:22 GMT -5
That is very odd. Make sure you check all carefully, but I'm sure you know that. The fellow who delivered mine lifted one out of the truck then dropped the second one on top with a loud thud. That much weight makes people strange...
Let us know what you think if you get them hooked up for a trial. I was surprised at how much difference there was by comparison to the 1L.Your info was very helpful and no need to apologize.
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Post by leonski on Jul 9, 2018 19:20:16 GMT -5
So that only 1 amp is handled per driver. This minimizes the chance of a debilitating lifiting injury or other medical issue.
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Post by craigl59 on Jul 9, 2018 20:51:01 GMT -5
leonski:
The computer fans are working OK but I am going to add a second to each amp and I took your advice and ordered the Noctua fans from Amazon today. Will post a picture of the final setup. Since all of the switching in the system is handled by the Furman, am triggering a 12 volt transformer off of that and that transformer feeds the fans -- thus they are only on when the amps are.
Better and better sound as the XPA-1 breaks in. Think you're right with Milt99's UPS issue. Hope he got the 2nd unit later today.
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Post by leonski on Jul 10, 2018 1:35:40 GMT -5
leonski: The computer fans are working OK but I am going to add a second to each amp and I took your advice and ordered the Noctua fans from Amazon today. Will post a picture of the final setup. Since all of the switching in the system is handled by the Furman, am triggering a 12 volt transformer off of that and that transformer feeds the fans -- thus they are only on when the amps are. Better and better sound as the XPA-1 breaks in. Think you're right with Milt99's UPS issue. Hope he got the 2nd unit later today. Transformer will supply 'noisy' AC. I think the Noctua is a DC or maybe uses a PWM power supply. Using a trigger output to a relay which turns 'on' the fan PS is a good idea. You can add some refinement, too. Time delay? Give amp a few minutes to warm before airflow begins. It should also be possible to add some kind of thermostat OR even run 12vdc fans on 9vdc which will sacrifice airflow for even quieter operation. Let me know how those Noctua work out! |
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Post by milt99 on Jul 10, 2018 11:56:38 GMT -5
The amp did not arrive yesterday  Looked a little deeper on the UPS tracking page this morning and all 3 packages have a separate tracking number under an umbrella number. According to the tracking for the undelivered amp it was loaded on a truck yesterday and out for delivery but not delivered. Today says that it was loaded on a truck and is currently out for delivery, again. |
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Post by novisnick on Jul 10, 2018 12:42:23 GMT -5
The amp did not arrive yesterday Looked a little deeper on the UPS tracking page this morning and all 3 packages have a separate tracking number under an umbrella number. According to the tracking for the undelivered amp it was loaded on a truck yesterday and out for delivery but not delivered. Today says that it was loaded on a truck and is currently out for delivery, again. |
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Post by craigl59 on Jul 10, 2018 13:10:16 GMT -5
milt99:
Have had the "repeat out for delivery" happen to me several times, most often with FedEx ground. With UPS have called them up and stressed to their agent that delivery was expected and waiting for a signature delivery a second day was not acceptable. In one case, they got in touch with the truck and the fellow came back and delivered the package.
Good luck. You're in a challenging position because you want the package but don't want to make the driver so angry they abuse the merchandise.
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Post by craigl59 on Jul 10, 2018 13:17:17 GMT -5
leonski:
Think I misspoke; am actually using a bench power supply to run the fans, triggered off the Furman. Use one of these to supply 12 volts to my RME ADI-2 DAC; several in the studio world suggested this as an improvement over the wall wart supplied by RME. Does, in fact, make the unit sound a bit more transparent and secure -- but just a little. With less good power supplies -- such as those provided by Audient -- the difference can be dramatic. With the fans, all you need is the 12 volts and who cares about quality. The XPA-1s are holding up well heatwise with extended listening sessions (every night) and the second fan will just be some insurance.
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Post by rbk123 on Jul 10, 2018 14:04:21 GMT -5
Good luck. You're in a challenging position because you want the package but don't want to make the driver so angry they abuse the merchandise. I once had a call tag for some speakers that I was expecting that were big and heavy. I signed the call tag, and put a note plus a couple of 32 oz bottles of micro brew out for the delivery person saying I knew they'd be heavy/painful but wanted to say thanks. Never heard anything but the speakers were fine and the beer was gone... Nowadays for the heavy stuff, if it's FedEx, I like to go to a place to pick the items up so as to avoid the anger/abuse risk. UPS is too far away for me for that. USPS I'll go out to their truck when they drive by to deliver the mail/package and haul it in myself. |
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