I don't like solder and desolder that's the reason I ask advice, I know LED sound because I used, I only need to know or better how can I calculate the LEDs values?
thats part of the fun
but only when prepared for it, hardwired, but not with everything tied together like a truck load
man, now I am tempted to dust off my old senheiser
always been a dream to own a nice tube headamp
any noise issues to consider ?
not one bit
its only a problem with printboards
but this kind of work you can desolder and solder a hundred times, as much you like
and it will still look fresh and new, like the first time
but without practice and experience.... yes, then you are right about it
any photos of a similar build ?
ehh, btw, power supply says 100ma
wouldn't that be big enough for a power amp ?
1. To change a design you first need to understand the design.
2. The alternative is to ask someone else to take the time and trouble to understand the design for you, then tell you how to change it.
1 is called DIY. 2 is called consultancy.
We have guided you to some understanding on CR first-order high-pass filters. Now I suggest you investigate valve biasing and load lines.
2. The alternative is to ask someone else to take the time and trouble to understand the design for you, then tell you how to change it.
1 is called DIY. 2 is called consultancy.
We have guided you to some understanding on CR first-order high-pass filters. Now I suggest you investigate valve biasing and load lines.
he was 'cocky', sure, but that is bloddy arrogant
we could try and have a look at some older posts
Use of LEDs in this way is well covered in Morgan Jones "Valve Amplifiers" 3rd Edition, which you can find here and there. It's really worth reading. Highly recommended.
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Hola Merlin.
I have a similar build using Nichicon 470uF/450V caps, and the result is very good.
I am using an external regulated-variable power supply and 6F8G bottles, so it can not be called "mini" amplifier
(the front cover is still provisional)
I have a similar build using Nichicon 470uF/450V caps, and the result is very good.
I am using an external regulated-variable power supply and 6F8G bottles, so it can not be called "mini" amplifier
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
(the front cover is still provisional)
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Should be okay, but better parallel two 220R 1/4W...
Yes, it can be as small as 470uF. 2200uF is calculated for a low frequency of under 1Hz or so (from the top of my head), so 470uF is good. Tip: use 2x220uF Oscon... a worthwhile improvement.
Yes, in the first stage. Don't know about using LED's in Cathode Followers...
Didn't I send you my schematic of the Morgan Jones with LED bias...?
Yes I see that you are using LEDs in the input tube but I have the same doubt like you to use it in the white cathode follower?
What about R7, somw people said 10K in place of 22K?
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An externally hosted image should be here but it was not working when we last tested it.
Here, download a copy of LTspice and have a play with these. Put the file 'dmtriode.inc' in the same directory (C:\Program Files\LTC\LTspiceIV) you put the 'MJ_6DJ8_optimized.asc' file in. Open the .asc file, right click on the schematic and select run. The simulation will run. Click on Vout to see the sinewave. Rightclick on the sinewave and select 'View\FFT' to see the FFT. You can substitute values or put in an LED and see the effect. Go 'View/Spice Error Log' (after running the Transient simulation) to see the THD. If you right click and select 'Edit Simulation Cmd.' you can simulate the AC (frequency) response or find the DC operating point.
View attachment Morgan_Jones_headamp_optimized.zip