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Post by darkarn on Mar 3, 2017 19:33:27 GMT
Thanks! You're right! Replacing just these transistors did the trick!
There is sound now, the RCA line out cuts out when headphone is inserted in as per designed, the relay circuit works as it should with two clicks (one upon switching on, another when the amp is ready) and the red LED lights up. The socket's LED also works as intended.
But now I am unsure which solder joint I should reflow since everything works. On one hand, I am thinking of just leaving it be (i.e. don't fix what is not broken), on the other hand, I should go fix what I can see, right?
Heck, I'll do it. I can see some that needs to be done (i.e. those blobby looking ones) but am unsure which others I should also reflow
Also, I can't hear much differences between the different settings for bypassing the capacitors and resistors. Is this intentional?
PS: I will be doing a second stream later (about 3pm GMT +8?) to discuss about what happened and to wrap it up with me fixing the chassis and then some final thoughts about the whole process
PPS: The transistors are way harder to remove than the relays due to their size. I am not kidding!
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Post by darkarn on Mar 4, 2017 8:38:23 GMT
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Rabbit
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Post by Rabbit on Mar 4, 2017 9:17:31 GMT
I'm glad that you finally got it to work. Quite a battle! Now it's on to the good bit ... listening.
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Post by darkarn on Mar 4, 2017 9:42:11 GMT
Thanks! It is indeed a battle. At one point of time I thought I almost lost it!
Now time for some burn in
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solderdude
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Post by solderdude on Mar 4, 2017 16:55:39 GMT
Glad you got it working.
The effect of this is much depending on the used tube.
In some tubes the audible effect will be none, in others the settings may lower the noise floor.
When you hear no differences with the input cap settings you are using a tube with low grid leakage !
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Post by darkarn on Mar 6, 2017 19:18:37 GMT
Thanks! I think my tubes are those with low grid leakage, hence the lack of audible effect. I decided to just bypass both capacitors and resistors anyway for now
And yes, the experience has been awesome so far! I will comment more once I test more though
Meanwhile, how do I know if a tube is too old for the auto bias to help with (and therefore should be changed)? I am using a RCA 12AU7A 1970s O-Getter Tall Grey Plates since about 2 years ago with my previous tube amp and am also using the same tube right now with the Ember. This tube is left on 24/7 since about 2 years ago, barring a few times where I have to switch off the power due to various reasons.
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sekar
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Post by sekar on Mar 11, 2017 17:50:24 GMT
I'm still thinking about 2nd HP amplifier that could give me possibility to easily roll tubes. There are a lot of old Soviet tubes around yet . I see there is no supercharger module for the new Ember 2 - 2.1 versions . As for me I'd rather purchase some parts for new Ember and build it according my point of view on some items. I see only one obstacle now to prevent me from this decision - need for linear power supply unit . There is no easy way to resolve this small problem. It's possible to build some single rail PSU based on sigma 11 project with ample toroidal trafo as first stage and to add some adjustable power supply unit to select output voltage as you could see here : www.ebay.com/itm/DC-DC-400W-8v-80v-10A-Digital-controlled-Boost-Step-up-Module-Power-Supply-/171115213962?hash=item27d742f48a:g:mJIAAMXQaZxSHbLyWhat could you say ? |
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solderdude
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Post by solderdude on Mar 11, 2017 23:12:58 GMT
Thanks! I think my tubes are those with low grid leakage, hence the lack of audible effect. I decided to just bypass both capacitors and resistors anyway for now And yes, the experience has been awesome so far! I will comment more once I test more though Meanwhile, how do I know if a tube is too old for the auto bias to help with (and therefore should be changed)? I am using a RCA 12AU7A 1970s O-Getter Tall Grey Plates since about 2 years ago with my previous tube amp and am also using the same tube right now with the Ember. This tube is left on 24/7 since about 2 years ago, barring a few times where I have to switch off the power due to various reasons. When a tube becomes noisy, distorts or one channel is noticeably softer than the other channel or when it becomes (overly) microphonic it is time to change the tube. |
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solderdude
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Post by solderdude on Mar 11, 2017 23:23:07 GMT
I'm still thinking about 2nd HP amplifier that could give me possibility to easily roll tubes. There are a lot of old Soviet tubes around yet . I see there is no supercharger module for the new Ember 2 - 2.1 versions . As for me I'd rather purchase some parts for new Ember and build it according my point of view on some items. I see only one obstacle now to prevent me from this decision - need for linear power supply unit . There is no easy way to resolve this small problem. It's possible to build some single rail PSU based on sigma 11 project with ample toroidal trafo as first stage and to add some adjustable power supply unit to select output voltage as you could see here : www.ebay.com/itm/DC-DC-400W-8v-80v-10A-Digital-controlled-Boost-Step-up-Module-Power-Supply-/171115213962?hash=item27d742f48a:g:mJIAAMXQaZxSHbLyWhat could you say ? The newer Ember has a built-in supercharger so it can handle heaters of 1A. Because the heater supply is switch mode the amp does NOT require a high current 48V power supply max power drawn is about 200mA. The used power supply must be able to handle a larger inrush current though. A 0.5A power supply will do. A simple linear power supply with LM317HV is more than enough to power the Ember. No need to go overboard with 400W switchers ! |
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sekar
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Post by sekar on Mar 12, 2017 19:46:43 GMT
Thanks Frans.
I need trafo with 2 x 24 v or 1 x 48 v secondary windings.
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solderdude
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Post by solderdude on Mar 12, 2017 21:37:05 GMT
2x 20V will do.
This will give 55V rectified and the regulator can easily drop 55V to 48V with 7V to spare.
As the max input voltage is about 60V I would not recommend to use more than 2x20V.
2x24V would give about 66V DC which is too much for the LM317HV and you would have to drop about 18V over the regulator which will increase heat in that part.
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sekar
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Post by sekar on Mar 12, 2017 22:03:31 GMT
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solderdude
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Post by solderdude on Mar 13, 2017 6:03:52 GMT
2x18V may be a bit too little.
this may turn out to be just 49V unregulated which is too little to regulate to 48V.
I believe Jeremy found out that he needed a 100W trafo 2x20V for the linear to work.
He had trouble with startup currents due to the switcher in the Ember when running 1A tubes.
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Post by darkarn on Mar 13, 2017 9:10:24 GMT
Thanks! I think my tubes are those with low grid leakage, hence the lack of audible effect. I decided to just bypass both capacitors and resistors anyway for now And yes, the experience has been awesome so far! I will comment more once I test more though Meanwhile, how do I know if a tube is too old for the auto bias to help with (and therefore should be changed)? I am using a RCA 12AU7A 1970s O-Getter Tall Grey Plates since about 2 years ago with my previous tube amp and am also using the same tube right now with the Ember. This tube is left on 24/7 since about 2 years ago, barring a few times where I have to switch off the power due to various reasons. When a tube becomes noisy, distorts or one channel is noticeably softer than the other channel or when it becomes (overly) microphonic it is time to change the tube. Thanks! Thankfully none of my tubes are showing such signs yet! |
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sekar
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Post by sekar on Mar 13, 2017 13:09:17 GMT
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