Hello everybody. Very loong time a go i purchase this amp. Leben CS 300. I have 1th version, what now no longer in production. To be honest, i dont remember, when i was purchase it. But will be around 13 years. During this time i everytime only change tubes and amp still working without any problem. I testing many tubes and i start using JJ electronic tubes finaly. Not expensive and sound is really good.
But month a go, when tubes brooken, i searching some info at internet, what else i can do with this amp. I finally i decide to modify this amp. First week i only seaching some info, what other DIY technicians do with this amp. I found some photos and info. More less, when someone do modify dont do anything crazy. Capacitors, amp feet pads, power fuse and thats it. And i try to do all what i found with my amp.
Maybe this post are better designed for DIYaudio. But i like more Head-fi. And my main listening are now only at headphones and specialy IEMs. So i focused on this.
First i must thanks here to 2359glenn , who send schematic here. This really help me. Its for X version, but there is small diference.
OK. Here some photos of modification what i found. I reduce picture resolution. This post will be huge.
I drew some information here: https://highfidelity.pl/@main-135&lang=en
Here is photo of my baby
I start with some easy to change parts. Exchange feet pads. My plan was use Finite Elemente Ceraball. But i want gold one. So only this part and power socket i order from Aliexpress. Rest only at local dealers. Here small complication. Original pads were screwed into the cover plate with screws. New one use 8mm threaded screws. I must use low profile nuts. And drill 8.5mm hole. Be careful. Components inside are near of cover plate and this can do problem. Short. New one will help with vibration and reduce it.
Left photo original pads, right new one. Look amazing. And gold champaine this is it.
All other photos are same. Left before and right after modify.
Next power socket. I use recommended Furutech gold plated. Look nice. In future i will try some audiphile fuse. But my audio are connected to power filter.
Now components inside. And this is after years of experience critical area of this amp. Volume/balance potentiometer. In amp used Alps blue. I dont like this parts. During time lost quality, sound starts to sizzle, stereophonic base not in middle and you must to exchange this alps, or for quick repaire use contact spray (I use IWETEC ELEKTRON from Germany). Rootcost - dust go inside part and rotary switches for input selector have similar problem. Its opened and due to tubes case of amp are open too. So easy way for dust go inside. And i want change it. I use Eizz rotary volume regulator with precise resistors inside. Problem is this balance Alps. I cannot change it. Tube ECC 83 of one channel are too close. So here only possible to exchange it for original one. If you use other volume regulator, dont forget about connection of pot shaft to GND of amp. You see it on photos. Because Alps are plastic, you see short between GND and small screw in corner. If you not do it, than start amp hum when you touch volume knob. Eizz are fully steel with case connected to GND. I measure it.
And now parts in amp. Here is internal photo inside amp before modify.
I read many internet pages about capacitors and peple who do this jobs really know, what is best (I hope). Iam electro engeneer in automotive. And audio are only my hobby. I had to do a lot of searching for information. And i found, that preferred caps in power supply are Audio Note. This i searching here in my country in local dealers, but ee. And i dont want orders this caps from China. I think engeneers knows, what they can do with fake capacitors. Finally i decide Nichicon from Japan. And use local dealer with guarantee of original one. All type what i use are Low ESR for 105° C. Here first cap from right side have protection at cover for prevention of short to resistor what are near of this cap. Nichicon are smaller, but i leave there this protection. All 4 caps 100uF/400V.
Cap for ECC 83 heaters. I double capacity to 4700uF/10V
Cap for ECC 83 plate. Original are 330uF/250V and i use 1000uF/250V 105°C.
Next caps that have the greatest influence on the sound. I order best in this category what i found - Miflex (Poland company) 0,47uF 600VDC Pap+PP+Oil. Top line from this company. And very expensive. But because iam ID...OT and dont check dimension, they not fit in. Grrr. So after this experience i really check dimension and order Mundorf MEO OIL line. They fit in perfectly and i dont need too much modify of components around this caps.
Next one are caps in feedback of topology. There is caps what protecting output transformer for DC voltage. This i understand. This caps are directly at the rotary switch for bass boost. Mundorf are much bigger, but fit well. 100uF/100V Mundofr Ecap RAW non-polarity caps.
FInally all filtering capacitors in amp what was there i change to Mundofr Ecap RAW non-polarity caps. I think this is not necessary. This caps working like battery in amp and filtering small voltage for correct set points of tubes. I read at one internet page, that cathode caps are important. So i change it too.
Here is finall picture of amp after modify.
I hope i dont forget about anything, what i change. If someone here have some idea or some more info about what else i can modify, i like to know it. Lets talk about it.
- I will try this audiophile fuse.
- Maybe output connectors - WBT. I use this amp with my Reference 3A Dulcet speakers too. High sensitive one.
- What type of tubes are you recommend me?
- I like to use some better resistors, what are for headphone output. Vishay non-magnetic i think will be best. But i found it only in Mouser dealer. Any idea?
If someone want do same job, dont forget to use insulating sleeves on parts, where its necessarily. Protecting short. And inside are high voltage. Se be careful.
About sound. As i say at the beginning. I listening mainly on IEMs. And i must say amp are fully dark. No any noise or hum. And i try very sensitive one with low impedance. Sound are amazing. I think amp are more cleare than before. And has lost none of its charm. Bass are more under control. Huge WOW effect after first testing.
Last photo is schematic of amp and area, where is resistors for headphone output. Someone increase serial resistance from 270 ohm to 1K ohm. And if i good remember, due to high impedance headphones.
But month a go, when tubes brooken, i searching some info at internet, what else i can do with this amp. I finally i decide to modify this amp. First week i only seaching some info, what other DIY technicians do with this amp. I found some photos and info. More less, when someone do modify dont do anything crazy. Capacitors, amp feet pads, power fuse and thats it. And i try to do all what i found with my amp.
Maybe this post are better designed for DIYaudio. But i like more Head-fi. And my main listening are now only at headphones and specialy IEMs. So i focused on this.
First i must thanks here to 2359glenn , who send schematic here. This really help me. Its for X version, but there is small diference.
OK. Here some photos of modification what i found. I reduce picture resolution. This post will be huge.
I drew some information here: https://highfidelity.pl/@main-135&lang=en
Here is photo of my baby
I start with some easy to change parts. Exchange feet pads. My plan was use Finite Elemente Ceraball. But i want gold one. So only this part and power socket i order from Aliexpress. Rest only at local dealers. Here small complication. Original pads were screwed into the cover plate with screws. New one use 8mm threaded screws. I must use low profile nuts. And drill 8.5mm hole. Be careful. Components inside are near of cover plate and this can do problem. Short. New one will help with vibration and reduce it.
Left photo original pads, right new one. Look amazing. And gold champaine this is it.
All other photos are same. Left before and right after modify.
Next power socket. I use recommended Furutech gold plated. Look nice. In future i will try some audiphile fuse. But my audio are connected to power filter.
Now components inside. And this is after years of experience critical area of this amp. Volume/balance potentiometer. In amp used Alps blue. I dont like this parts. During time lost quality, sound starts to sizzle, stereophonic base not in middle and you must to exchange this alps, or for quick repaire use contact spray (I use IWETEC ELEKTRON from Germany). Rootcost - dust go inside part and rotary switches for input selector have similar problem. Its opened and due to tubes case of amp are open too. So easy way for dust go inside. And i want change it. I use Eizz rotary volume regulator with precise resistors inside. Problem is this balance Alps. I cannot change it. Tube ECC 83 of one channel are too close. So here only possible to exchange it for original one. If you use other volume regulator, dont forget about connection of pot shaft to GND of amp. You see it on photos. Because Alps are plastic, you see short between GND and small screw in corner. If you not do it, than start amp hum when you touch volume knob. Eizz are fully steel with case connected to GND. I measure it.
And now parts in amp. Here is internal photo inside amp before modify.
I read many internet pages about capacitors and peple who do this jobs really know, what is best (I hope). Iam electro engeneer in automotive. And audio are only my hobby. I had to do a lot of searching for information. And i found, that preferred caps in power supply are Audio Note. This i searching here in my country in local dealers, but ee. And i dont want orders this caps from China. I think engeneers knows, what they can do with fake capacitors. Finally i decide Nichicon from Japan. And use local dealer with guarantee of original one. All type what i use are Low ESR for 105° C. Here first cap from right side have protection at cover for prevention of short to resistor what are near of this cap. Nichicon are smaller, but i leave there this protection. All 4 caps 100uF/400V.
Cap for ECC 83 heaters. I double capacity to 4700uF/10V
Cap for ECC 83 plate. Original are 330uF/250V and i use 1000uF/250V 105°C.
Next caps that have the greatest influence on the sound. I order best in this category what i found - Miflex (Poland company) 0,47uF 600VDC Pap+PP+Oil. Top line from this company. And very expensive. But because iam ID...OT and dont check dimension, they not fit in. Grrr. So after this experience i really check dimension and order Mundorf MEO OIL line. They fit in perfectly and i dont need too much modify of components around this caps.
Next one are caps in feedback of topology. There is caps what protecting output transformer for DC voltage. This i understand. This caps are directly at the rotary switch for bass boost. Mundorf are much bigger, but fit well. 100uF/100V Mundofr Ecap RAW non-polarity caps.
FInally all filtering capacitors in amp what was there i change to Mundofr Ecap RAW non-polarity caps. I think this is not necessary. This caps working like battery in amp and filtering small voltage for correct set points of tubes. I read at one internet page, that cathode caps are important. So i change it too.
Here is finall picture of amp after modify.
I hope i dont forget about anything, what i change. If someone here have some idea or some more info about what else i can modify, i like to know it. Lets talk about it.
- I will try this audiophile fuse.
- Maybe output connectors - WBT. I use this amp with my Reference 3A Dulcet speakers too. High sensitive one.
- What type of tubes are you recommend me?
- I like to use some better resistors, what are for headphone output. Vishay non-magnetic i think will be best. But i found it only in Mouser dealer. Any idea?
If someone want do same job, dont forget to use insulating sleeves on parts, where its necessarily. Protecting short. And inside are high voltage. Se be careful.
About sound. As i say at the beginning. I listening mainly on IEMs. And i must say amp are fully dark. No any noise or hum. And i try very sensitive one with low impedance. Sound are amazing. I think amp are more cleare than before. And has lost none of its charm. Bass are more under control. Huge WOW effect after first testing.
Last photo is schematic of amp and area, where is resistors for headphone output. Someone increase serial resistance from 270 ohm to 1K ohm. And if i good remember, due to high impedance headphones.
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