ANN: LF01 Discrete/Hybrid Opamp Module

[linuxguru]

I am Planning to buy 10 pcs of LM318N ...
I think it is same as LM318m but the package as mentioned for Lf01.

The LM318N is DIP-8, while the LM318M is SOIC8 (SMD). If you plan to use my LF01 PCB, you need the SOIC8 version. If you build it on a perfboard, either one will be ok, but the LM318N will be easier to handle.

 

[dipolar]

The LM318N is DIP-8, while the LM318M is SOIC8 (SMD). If you plan to use my LF01 PCB, you need the SOIC8 version. If you build it on a perfboard, either one will be ok, but the LM318N will be easier to handle.

Is your PCB on sale ,Then I can go for smd which is much cheaper?
I don't want to go into PCB making as of now.

 

[linuxguru]

Is your PCB on sale

Sure - bare boards and kits are available. PM or email me for details.

 

[atupi]

I have finished one LF-01 module thanks to Siva ideas and worked from the first time. I have followed all the parts recomendations.
Being only one channel equipped i noticed slight modifications in the sound but i think i need to finish also the other one to have a complete opinion.
What was obvious after installed LF-01 was a higher noise from that channel. I could hear from the tweeter a louder sssssssssshhh sound. Any opinion about that noise Siva or someone else ?

 

[linuxguru]

... i think i need to finish also the other one to have a complete opinion.
What was obvious after installed LF-01 was a higher noise from that channel. I could hear from the tweeter a louder sssssssssshhh sound.

Yup, you need two identical ones to assess imaging. Regarding the hiss, I haven't noticed it, but it could be EMI/RFI pickup from long and/or magnetic leads. Also check the output DC offset with the LF01 installed.

 

[bcmbob]

atupi, my experience was quite the opposite. Artifacts in the sound were lessened not added. Is the hiss heard over/through music or only when no signal is being amplified?

 

[atupi]

The hiss is present with or without signal but you can hear it when you put your ear close to the tweeter. I cant say is audible from my couch but the difference between channels is audible. Hope today to build the second one and hear the real difference between MyRefC and MyRefC+LF01.

 

[atupi]

I have finished the second LF01 and installed. Sounds very nice and sweet and a bit sprinsing because even sounds a bit roundish i can hear some thins better now (voices, cimbals).
Also because of this roundish sound i feel like i have lost a bit of soundstage focus.

 

[bcmbob]

atupi, Glad you like what you are hearing. I had the same impressions. You might have to adjust the location/angle of your speakers to regain the stage resolution you desire.

Is the hiss lessened with both modules installed?

 

[atupi]

Yes they sound very dark. Regarding hiss now i hear even more noise like a noise from AM between stations and i suppose this is because i have LF's installed on 2pcs dip8 sockets plus the socket from MyRef pcb.

 

[bcmbob]

I have the same number of sockets so that may not be the cause of the hiss. Comparing your photo to the one in the first post,the cap is the most obvious difference. Did you try to get info on the best selection for that position? Siva may be able to report how significant that is.

 

[AndrewT]

I am Planning to buy 10 pcs of LM318N (Price 1 : INR 78 ) from Kits n spares; very good VFM proposition for a performance Opamp.

I think it is same as LM318m but the package as mentioned for Lf01.

Might be worth buying a couple of LT318 for comparison.

 

[AndrewT]

Could the excessive hiss be a symptom of oscillation?

 

[dipolar]

Might be worth buying a couple of LT318 for comparison.

LT318 is not available.

Could the excessive hiss be a symptom of oscillation?

Oscillations or polarity of transistors.

 

[AndrewT]

LT318 is not available.

Buy, price and suppliers for LT318

 

[AndrewT]

Oscillation creates weird circuit behaviour. Sometimes this comes out as noise.

 

[dipolar]

Oscillation creates weird circuit behaviour. Sometimes this comes out as noise.

Thankfuly ,Only circuit which oscillated in my life were TDA2030 based amplifier and Elektor hexfet amplifier.

Tda 2030 were counterfeits which I realized when I replaced them with another lot. Hexfet amp is a mystery so I am at edge of dropping it.

 

[atupi]

I have the same number of sockets so that may not be the cause of the hiss. Comparing your photo to the one in the first post,the cap is the most obvious difference. Did you try to get info on the best selection for that position? Siva may be able to report how significant that is.

For that position Siva recommended ceramic type but i managed to squeeze a FKS2 and i know this type worked better in Myref versions. I will try also a ceramic (maybe) because is so hard so swap components on that small pcb. I worked exclusively with magnifing lens. Unfortunately not all transistors are made by Toshiba and i founs also some cheap Fairchild but all of them from Mouser.

 

[atupi]

Small problem and i don't know where to look. On the left channel i have a small thump on powering On and also on powering OFF. Is not related to a specific LF module because if i roll the LF modules between channels the problem remains on the LEFT channel.
When i put back the plain LM318 the problem is gone.

 

[linuxguru]

*Long bump up* - several mods have been made to the LF01 (single) and LF02 (dual) over the last few years. Here's the current simulation schematic for the LF02 (one channel shown), which will also work for the LF01. Various opamps may be used, including the LT1361 and the LM6172 (in the LF02). The LF02 prototype shown in the picture is the latest, with all-Japanese low-noise BJTs, Dale MFRs in the signal path, Wima FKS02 bypass and LM6172 opamp - and it's also subjectively the best sounding so far in a 2-channel MiniRef amplifier.