On the lower outputs is it a good idea to match the diodes? (The ones connected from the driver emitters to the output node.)
They are not suitable for that circuit.I try in the past.The sound will be very distorted.I tried many modifications for working properly but in the end i decided to let the stock transistors.They need other way of compensation & other values of some resistors....
OK, Update. The older version (before 2021) use 2SD1047, this is my case. The newer version, since 2021, PCB updated with ST 2SC5200. I am ordering one on eBay for the new one.
A few years back my stock (bought assembled) MX50x2 incinerated at power up. (One channel only.) I rebuilt with genuine Toshiba 2SC5200N and TTA004/TTC004 from Mouser and it was fine. I don't like the 2SD1047 that come with these kits... [Considering that 2SC5200 cost more I suspect that the manufacturer might have come to a similar conclusion.]
Never had a failure with Toshiba 2SC5200N or the old transistors removed from junked (recycled) receivers.
Never had a failure with Toshiba 2SC5200N or the old transistors removed from junked (recycled) receivers.
@kozard Thank you for the information. I like Toshiba transistors, they are made of Triple Diffused method, and I am professionally knows what's that.
I simulated in the Micro-Cap 12, the Toshiba TTC5200 did have a little bit high THD numbers, but the real listening tell another story. Even I am worrying about the quiescent currents variance, but the static voltage at the output have very satisfactory numbers 0.1mV and 1.4mV.
I simulated in the Micro-Cap 12, the Toshiba TTC5200 did have a little bit high THD numbers, but the real listening tell another story. Even I am worrying about the quiescent currents variance, but the static voltage at the output have very satisfactory numbers 0.1mV and 1.4mV.
The measured THD was very low on the MX50x2 using 2SC5200N.
In measurements on another amplifier design (L20.5) I achieved the lowest THD using Toshiba 2SC5200/2SA1943 and 2SC5171/2SA1930.
I think it is very hard to model transistors well enough to simulate THD.
In measurements on another amplifier design (L20.5) I achieved the lowest THD using Toshiba 2SC5200/2SA1943 and 2SC5171/2SA1930.
I think it is very hard to model transistors well enough to simulate THD.
Is there any way to use lateral mosfet output transistors with these boards? Anybody tried it?
Yes ... In fact , see here https://www.diyaudio.com/community/...ain-stability-simulated-vs-real-world.407089/
Hello !
Anyone has tried to reduce gain on LJM Preamp9.
Seems to be ~x10, but x2 - x3 would be sufficient for me
Thanks for any help !
Anyone has tried to reduce gain on LJM Preamp9.
Seems to be ~x10, but x2 - x3 would be sufficient for me
Thanks for any help !
Any Preamp 9 schematics to see what could be done more effectively if you reduce gain, if possible simulating it in LTSpice?
Sorry, no schematics availaible
I've asked LJM_LJM , and his answer is :
" Cannot reduce magnification. There will be self-excitement. Oscillation "
And didn't answered when I asked him to provide schematics
Markings on some electronic components have been erased on boards ,
The components are misemployed, tantal smd as input/output capacitors...missing space to replace
Nothing to do with this junk, > trash-can, 15$ lost .
There are lots of good preamp kits on Aliexpress, discrete and IC. What do you need the preamp for?
Sometimes you just need to change the IC for a a legit one bought on Mouser or elsewhere.
For discrete preamp that would be more difficult. Also adding a good power supply, also available on AE, can improve things. Sometimes the kit already has a good PS included, even a kit with transformer.
Sometimes you just need to change the IC for a a legit one bought on Mouser or elsewhere.
For discrete preamp that would be more difficult. Also adding a good power supply, also available on AE, can improve things. Sometimes the kit already has a good PS included, even a kit with transformer.
I ve just bought this preamp by curiosity (single-ended with 2 npn transistors) , after I read it was described as the 8th wonder of the world by LJM_LJM
https://www.diyaudio.com/community/threads/ljm-audio.180625/page-53#post-4752813
I was really disappointed, compared to other parts from LJM_LJM, L15 Mos amplifier , excellent quality/price ratio
https://www.diyaudio.com/community/threads/ljm-audio.180625/page-53#post-4752813
I was really disappointed, compared to other parts from LJM_LJM, L15 Mos amplifier , excellent quality/price ratio
Fred, do you know of any tube preamp kit around 50$ from aliexpress thats half decent? Just wanted to try and compare it to other preamps that i have