Curved paths
Hello to all,
I am also the owner of this great amplifier. I got it from HERE and it arrived with original Sanken transistors.
I think it is a nice final amp version of L12-2 (board says ver. 4), so decided to use some of my best components to solder. I have just one question, if I will use only one pair of transistor, nothing has to be changed, correct? Basically the second pair seems to be optional, but I thought it would be good to ask...
I have also some fun with designing curved paths, it’s quite relaxing in covid days 🙄
Hello to all,
I am also the owner of this great amplifier. I got it from HERE and it arrived with original Sanken transistors.
I think it is a nice final amp version of L12-2 (board says ver. 4), so decided to use some of my best components to solder. I have just one question, if I will use only one pair of transistor, nothing has to be changed, correct? Basically the second pair seems to be optional, but I thought it would be good to ask...
I have also some fun with designing curved paths, it’s quite relaxing in covid days 🙄
Just checking - did anyone had a chance to try JLM L12-2 amplifier with more or less SanKen pair/s transistors?
Hi, yes you can use just one pair of outputs, no problem. But why would you? Two pairs is better, and the boards are designed for it.
Hello 🙂 I want to use two pairs in the final amplifier version. I just thought it would be good to have amp with with less power for 6 ohms 30W speakers.
High Frequency problem
Hi, there is HF problem. I tested/compare with my technics amplifier HF was very weak. I connected fiio player and ljm l12-2 has no volume control. So, ljm l12-2's input empedance 100k? Is this empedance problem or what?
Hi, there is HF problem. I tested/compare with my technics amplifier HF was very weak. I connected fiio player and ljm l12-2 has no volume control. So, ljm l12-2's input empedance 100k? Is this empedance problem or what?
There are no general problems with high/mid frequency on the L12-2. It is a very stable and good proven basic design. Perhaps your amp is defective?
Hi,
are You sure that Your´s is a genuine LJM?
There are some counterfeits around and i wouldn´t guarantee for anything with those.
DC-input impedance is 100k, yes, dropping to 10k||680pF at AC.
jauu
Calvin
are You sure that Your´s is a genuine LJM?
There are some counterfeits around and i wouldn´t guarantee for anything with those.
DC-input impedance is 100k, yes, dropping to 10k||680pF at AC.
jauu
Calvin
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I have ver4 and C4&C6 are 1uf, 5w resistors are 0.2Ohm. 10uf and 0.15ohm in your graph recommended or?
I recieved the ver4 today with thesame value's as mdareniz. Pcb looks original, (original design ljm-ljm@foxmail.com)
Thinking to replace the caps with high grade one's (nichicon). Pcb came with rubycon's and samxon.
If you look to the modification page, c4 and c6 are 1uf and the resistors are 0.22. Thesame value as delivered. Or am i wrong?
Thinking to replace the caps with high grade one's (nichicon). Pcb came with rubycon's and samxon.
If you look to the modification page, c4 and c6 are 1uf and the resistors are 0.22. Thesame value as delivered. Or am i wrong?
If the circuit and all the material are the same as LJM. So it must be orjinal.
I was listening Jethro Tull's concert album (not best recording). I connected Fiio to technics amp. it's much more clear sound (I think, my observation). LJM's amp. looks like a little "curtained" or there is some filter in sound. It's not easy to explain. I'm testing and waiting for pot. for input.
Hi,
the original LJM hows his Logo on a blue PCB.
Since it´s the very nature of fakes to camouflage, a same circuit utilizing seemingly identical devices is still no original and may contain unsuitable parts.
So far the positive reviews about this little amp are in the vast majority.
That´s the reason I assumed that your L12 may either be fake, or something in the chain might not match well or Your listening experience/taste simply differs and You prefer a ´cleaner sound´.
jauu
Calvin
the original LJM hows his Logo on a blue PCB.
Since it´s the very nature of fakes to camouflage, a same circuit utilizing seemingly identical devices is still no original and may contain unsuitable parts.
So far the positive reviews about this little amp are in the vast majority.
That´s the reason I assumed that your L12 may either be fake, or something in the chain might not match well or Your listening experience/taste simply differs and You prefer a ´cleaner sound´.
jauu
Calvin
Calvin you'r right. I have bought from JOJOHIFI Store.
Now, I saw (I have 4 kit), one of the kit's C6's value 10μf (not 1μf) and electrolytic. Is this ok or it must be bipolar capacitor?
Now, I saw (I have 4 kit), one of the kit's C6's value 10μf (not 1μf) and electrolytic. Is this ok or it must be bipolar capacitor?
hi 🙂 how C4 and C6 effect the sound? Some of the kits, they are tantalium, electrolytic, sometimes bipolar or not, sometimes 10uf or 1uf. Calvin says they are related supply voltages. How it effect the sound?
I tested two different kits as one has 1uf tantaliums and other one has 10uf tantalium (C6) and 10uf bipolar electrolytic. I think 1uf's kit's sound a little clearer than other. There is no any other differences between the kits (if transistors are not fake).
I ordered 1uf, MKS2 capacitors. I will try them.
Note that testing with, Jethro Tull concert record (20 years of JT. it's very poor recording), Steely Dan, very very good record (Two Against Nature), Mozart's requiem(H.V.Karajan); very crowded chorus. Beethoven quartets(Amadeus Quartet's, DG.), natural violin sound. And others.. I have no oscillascope 🙁
I tested two different kits as one has 1uf tantaliums and other one has 10uf tantalium (C6) and 10uf bipolar electrolytic. I think 1uf's kit's sound a little clearer than other. There is no any other differences between the kits (if transistors are not fake).
I ordered 1uf, MKS2 capacitors. I will try them.
Note that testing with, Jethro Tull concert record (20 years of JT. it's very poor recording), Steely Dan, very very good record (Two Against Nature), Mozart's requiem(H.V.Karajan); very crowded chorus. Beethoven quartets(Amadeus Quartet's, DG.), natural violin sound. And others.. I have no oscillascope 🙁
LJM L12-2 PCB
So I got my new LJM L12-2 amplifier PCB boards in black matte version with wider and curved traces. Instead of provided components from China I used genuine Nichicon audio caps, better resistors and I am super satisfied! The sound is impressive!
I did quick test a few minutes ago, I cut off one pair of Sanken transistors and it look like the amp is still quite powerful for my needs. I feed it with 42V-0V-42V after filtering with current 5A.
So I got my new LJM L12-2 amplifier PCB boards in black matte version with wider and curved traces. Instead of provided components from China I used genuine Nichicon audio caps, better resistors and I am super satisfied! The sound is impressive!
I did quick test a few minutes ago, I cut off one pair of Sanken transistors and it look like the amp is still quite powerful for my needs. I feed it with 42V-0V-42V after filtering with current 5A.
Perhaps this is very quick reaction. I connected a parallel 1uf polyester capacitor to C6 and my sound corrected. Please test..
mkp2 is the best capacitor type for signal stage (not mks2). I couldn't find yet.
If you want to read The Capacitor for High End Audio Applications.
mkp2 is the best capacitor type for signal stage (not mks2). I couldn't find yet.
If you want to read The Capacitor for High End Audio Applications.
If I edit my previus post, I would do. I tested on another kit, I changed C6 value and type of capacitor, nothing changed in sound. ok forget my previous post. Why don't we edit our posts 😱
capacitor type
In Bob Cordell's documents, write dc servo paralel to C8 as
"We will see that the single biggest reason for employing a DC servo is the elimina-tion of the electrolytic capacitor. The DC servo is a smaller and less expensive solution that provides much higher sound quality and performance.".
Did anybody used or test this? Why we increase the value of C8 (now 1000uf), it's also polar in the circuit!? Also another option is use 220uf bipolar capacitor? One more option adding a paralel 0.1uf quality cap to C8?
Please share your experiance 🙁
(also C4&C6 must be bipolar. any comment?)
In Bob Cordell's documents, write dc servo paralel to C8 as
"We will see that the single biggest reason for employing a DC servo is the elimina-tion of the electrolytic capacitor. The DC servo is a smaller and less expensive solution that provides much higher sound quality and performance.".
Did anybody used or test this? Why we increase the value of C8 (now 1000uf), it's also polar in the circuit!? Also another option is use 220uf bipolar capacitor? One more option adding a paralel 0.1uf quality cap to C8?
Please share your experiance 🙁
(also C4&C6 must be bipolar. any comment?)
Well After Reading this post I am going to give it a try. I give up chassing thé hum of my 300B.
I have a 6at7 tube preamp I will use on it.
For a first build I think of using a switching power supply.
How Many watts Can I expect with a 45v supply ?
I have a 6at7 tube preamp I will use on it.
For a first build I think of using a switching power supply.
How Many watts Can I expect with a 45v supply ?
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