solderdude
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Post by solderdude on Dec 15, 2017 10:30:04 GMT
What alternatives are available in this case? (I feel that this is a good-to-have rather than a must-have unless the power supply in the house is that unclean though) Well Jeremy and I discussed this a few times. Even before Atomicbob published his ripple lowering idea using an inductor we spoke about using an extra regulator but this 'eats' a few volt. Not a problem for the 48V vesions but less desirable for 24V versions. This would lower the ripple and power supply noise but does not do anything against common mode currents. Thought of using a transformer as common mode filter (a bit Similar to AtomicBobs idea) but that one does not lower common mode currents. So... were thinking about it and have to do some experiments one day. Targets are not too loose too much voltage, lower PS noise/ripple and common mode currents. All this in a small and not too expensive add-on which is not too expensive to ship. No idea when it comes to see daylight though. |
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Post by darkarn on Dec 16, 2017 3:44:42 GMT
I use an attenuator whenever possible. That means that you are tracking at the best part of the pot and it gives you a much finer control over slight volume adjustments. With the Ember, you will get a slightly more ‘tubey’ flavour too. Personally, I think amps are working at their ‘best’ when you around 12 to 3 o clock. I know that some feel the need to have it low because then it feels like a powerful amp and all that, with loads of volume left at your fingertips, but on the whole, the second half of the pot travel rarely gets used because of that. I kind of compare it to microphones .... I try to raise the volume of a mic so that the peaks hit a certain level. Then the self noise of the mic is left away at the bottom of the sound. Too high, and it gets compressed and then it clips once it hits zero db, too low and the clarity is there but so is the noise. Get it right and the mic sounds full with low noise. The same happens with headphones, but the other way around!! Thanks for the tip, let me see how this works out! What alternatives are available in this case? (I feel that this is a good-to-have rather than a must-have unless the power supply in the house is that unclean though) Well Jeremy and I discussed this a few times. Even before Atomicbob published his ripple lowering idea using an inductor we spoke about using an extra regulator but this 'eats' a few volt. Not a problem for the 48V vesions but less desirable for 24V versions. This would lower the ripple and power supply noise but does not do anything against common mode currents. Thought of using a transformer as common mode filter (a bit Similar to AtomicBobs idea) but that one does not lower common mode currents. So... were thinking about it and have to do some experiments one day. Targets are not too loose too much voltage, lower PS noise/ripple and common mode currents. All this in a small and not too expensive add-on which is not too expensive to ship. No idea when it comes to see daylight though. This sounds hard, but for the first problem, is it possible to use different regulators for different voltage version? Alternatively, is it possible to "put back" the lost voltage so to speak? |
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Post by lobalwarming on Dec 16, 2017 6:09:05 GMT
Can't speak for Frans, but getting a regulator to be say...125% efficient is going to run into tough opposition from the laws of physics. But...if we could hook up our G1217 amps to our perpetual motion DC generators we could bypass the issue.
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kev
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Post by kev on Apr 7, 2018 0:22:20 GMT
Anyone know of a good 48V linear power supply kit I can build? Or at least an appropriate linear PS for Ember 2.
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solderdude
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Post by solderdude on Apr 7, 2018 7:17:09 GMT
The linear PS for 48V should be able to deliver 2A peaks for the start-up current.
A 100W transformer is about the minimum required and one of the reasons why Jeremy stopped with his build... + the enclosure and shipping costs.
He still has PCB's I reckon as well as parts. You will probabbly only need to find an enclosure.
Perhaps shoot him an e-mail.. (might take a while before he answers sometime)
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rhino
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Post by rhino on May 23, 2018 14:30:07 GMT
Hi All...new to the forum, but grateful for all the info!
I have recently purchased a Project Ember and Project Polaris. I am having power/volume issues with both. I was using a Dual 1219 turntable last night through a Emotiva XPS-1 Phono Pre-amp to both the Ember and Polaris and both seemed underpowered. I switched over to a Tascam CD-200il and had the same issues. Both amps are brand new. I searched head-fi, here, and the web for burn-in suggestions, but came up empty. Any suggestions?
THANKS!
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solderdude
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Post by solderdude on May 23, 2018 18:28:41 GMT
What setting are the input attenuators in ?
What headphones are you using ?
What output resistance setting is used ?
How loud does your headphone play directly from the CDP headphone out ?
Are there other devices connected to the input at the same time ?
When the CDP is connected directly to one of the amps only for instance ... is the gain still too low ?
The gain of the Ember (particularly) is often found to have too much gain.
It is not a burn-in issue of any kind.
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rhino
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Post by rhino on May 23, 2018 19:36:08 GMT
I am using HD800S and Hifiman Edition Xv2, also tested with some HD650S. I tried various settings for both of the amps, only slight improvement. The X2 usually responds well to low setting on the Ember, at least as tested on my Uncle's it really got them kicking. Senns, both 800 and 650, were typically good at the mid setting. I tried all three headphones and both amps, and on the turntable, I actually could turn the ember all the way up without hearing much of a difference. From 6 o'clock to 11 o'clock on the dial, there was hardly any sound at all. When I switched to the CD player, the Polaris finally had some power, and that was with low gain and high AT, I believe. But, for both amps, I was surprised.
I have been using stock cables, with quarter inch plug.
I had the headphones going directly into the amps and amps into the CD player. I did have the Emotiva phono pre-amp in line on the turntable, but that was it.
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solderdude
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Post by solderdude on May 23, 2018 20:58:26 GMT
Both amps should be playing the HD800 and 650s on very loud levels. The Xv2 should play uncomfortably loud.
It is highly unlikely both amps would have the exact same fault and play softly.
When it plays 'normal' using the CDP and softer on the turntable then, most likely, either the pre-amp does not have enough gain or output voltage or a low output voltage cart is used ?
The Polaris, on high gain, has 17x gain.
This means to reach 16V (max output voltage) peak levels of 1V on the input would be enough.
So a 2V output voltage would most likely be enough to reach max output voltage with peak levels.
HD650 and HD800 should reach peak levels of 125dB (so average of 110dB) which is very loud.
The gain of the Ember is tube dependent.
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rhino
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Post by rhino on May 29, 2018 14:48:45 GMT
Thank you for the quick replies and the help.
I apologize for the amateur questions!
I went home and moved the gain switches up, and that solved the power problems for the Ember!
I will continue to make adjustments to the Polaris, but it has seemed to depend on what record you are playing more than anything.
Thanks solderdude!
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solderdude
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Post by solderdude on May 29, 2018 15:39:54 GMT
No problem... how else do we learn ?
Indeed records can have quite a difference in loudness.
Most vinyl is from before the loudness wars and the mastering engineer usually looked at peak levels and depending on how high they were and how often used some compression or lowered the average levels without compromising noise levels too much.
Especially high dynamic range records, (classic, Jazz) often was recorded softer so the crescendo's were not clipped.
Solutions could be:
Modify the RIAA pre-amp to have a higher gain.
Find a higher output voltage cartidge.
Use a higher gain tube (at the expense of noise) for the Ember.
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Post by deafear on Jun 4, 2018 4:15:08 GMT
I have a lot of adapters and like trying all kinds of different tubes in my ember. It really is a tinkerer's dream.
I managed to acquire a bunch of different tubes in bulk, so I've been doing a lot of research on running a pentode in triode mode, and had some questions. The example tube I picked for research so far is the 6au6 (because I have some).
It sounds like you can achieve triode mode by connecting g2 (screen) to the plate. Some sites I came across say to wire a resistor in series to avoid exceeding the screen grid power rating. How do I find out what the screen grid power rating is? I've looked on the data sheets and couldn't find a clear Answer.
Also I'm assuming that a pentode in triode mode would make only one triode, so I would need to make an adapter to connect 2 tubes, correct?
Sorry if this requires a long answer. I'm an amateur with some electronics experience from an HVAC degree, but nothing this advanced, so i figured i better ask first.
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solderdude
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Post by solderdude on Jun 4, 2018 4:49:23 GMT
screen grid power could only be problematic when used on higher voltages and anode powers. The currents are so low in this design that it is not of any importance. Yes, you would need an adapter with 2 tubes to mimic a dual triode. Try both configs:  |
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Post by deafear on Jun 6, 2018 1:54:47 GMT
Thanks! That made my day.
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sekar
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Post by sekar on Jul 10, 2018 19:07:40 GMT
Frans,
Why not to implement slow turnon feature for possible linear PSU schematic for Ember ?
I realized this feature in my PCB's for new PSU. I used LM3X7 as stabilizers . Turnon time could be relatively easy programmed by changing of capacity of the cap. There are only 4 additional parts in this addon.
Original extended manual located on TI site contains some schematic which give you a way to increase 1.5A barrier stipulated.
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