And playing now! Actually sweet and listenable. I really do not know about it's qualities because the playback-chain is really not up to par. The Thorens is old and wobbly, it's Ortofon MM needle is worn, the amp is a transistor Sony and the speakers are small Acoustic Energys... But I have started my first self build, proud and happy! Its reasonably silent as well when playing music, even when lifting the needle off the record. Now up to new tubes and a new cabinet... Will report back one day...
Thanks for 'listening' and cheers again, Stef
Thanks for 'listening' and cheers again, Stef
With some assistance from others, the original conversion data has been upgraded to focus on the 3 tube version at the same place http://homepage.ntlworld.com/lez/Yaqin MS-22B/Putting 'Life' into the Yaqin MS-22B.pdf
The original Yaqin MS22/23B after conversion has been affectionately re-named the LesBox.
With extra photos it is hoped that those who had doubts will now have a little more confidence in doing this work, the rewards are so much worth it. I have received many complimentary e-mails and mentions on Forums, the last one which I attach below, was such a pleasure to receive and hopefully will encourage others. All the best for 2015.... Les Carpenter
"I don't want to sound over the top about this, but you would have to buy some very expensive gear to get anywhere near this level of sound staging and natural tonality. I'm having a hard time believing what I'm hearing. The Lesbox with Full Music tubes is the buy of the century. Thank you Les Carpenter. You have no idea how much joy you have brought into my life."
The original Yaqin MS22/23B after conversion has been affectionately re-named the LesBox.
With extra photos it is hoped that those who had doubts will now have a little more confidence in doing this work, the rewards are so much worth it. I have received many complimentary e-mails and mentions on Forums, the last one which I attach below, was such a pleasure to receive and hopefully will encourage others. All the best for 2015.... Les Carpenter
"I don't want to sound over the top about this, but you would have to buy some very expensive gear to get anywhere near this level of sound staging and natural tonality. I'm having a hard time believing what I'm hearing. The Lesbox with Full Music tubes is the buy of the century. Thank you Les Carpenter. You have no idea how much joy you have brought into my life."
I took a hard copy today and was stunned to find that I had not enclosed the drill template! Geez! Anyway, it is in there now, sorry peeps, it was all a bit of a rush job in between other tasks. It is hoped to add another part later detailing how to fit SUT's for using a MC Cartridge. This will be based on a persons trials and tribulations he experienced to achieving his goal!
Again a massive thanks to Les! Even without the 'up to par' gear, playing records is very satisfying indeed... And, I am very much looking forward looking to including a SUT in the amp. I have tried it in varying ways, but hum issues were plaguing me... I got it working as a stand alone setup. But I am convinced getting rid of several terminations and extra interlinks will improve matters again!
Merry Christmass to all you music folk!
Merry Christmass to all you music folk!
Variations from WAD phono
Hi Les,
you have been exceedingly kind in posting your upgrades and helping everyone who asks. Thank you. I'm excited enough to try to modify my Yaqin 12B; probably bypassing the linestage section.
As you had said you based your upgrades on the WAD phono I got out June and August 2000 HiFi World articles (I think these are the WAD design) to read up about it. In doing so I noticed a couple of variations. One is your 2nd RIAA section is a wee bit different. Have you recalculated the time constants?
The other was the size of the coupling cap. The Hi Fi world article suggests with a 0.015uF cap the roll-off is -3dB at approximately 10Hz; with 8.2nF or 3.9nF this would be set to 20Hz or 40 Hz respectively. Your 0.1uF is about 6 times bigger.
Please don't think I am criticising (I don't know enough) but I'm interested in your choices and decisions so I can try to learn a little.
Thank you again
Merry Christmas
tim
Hi Les,
you have been exceedingly kind in posting your upgrades and helping everyone who asks. Thank you. I'm excited enough to try to modify my Yaqin 12B; probably bypassing the linestage section.
As you had said you based your upgrades on the WAD phono I got out June and August 2000 HiFi World articles (I think these are the WAD design) to read up about it. In doing so I noticed a couple of variations. One is your 2nd RIAA section is a wee bit different. Have you recalculated the time constants?
The other was the size of the coupling cap. The Hi Fi world article suggests with a 0.015uF cap the roll-off is -3dB at approximately 10Hz; with 8.2nF or 3.9nF this would be set to 20Hz or 40 Hz respectively. Your 0.1uF is about 6 times bigger.
Please don't think I am criticising (I don't know enough) but I'm interested in your choices and decisions so I can try to learn a little.
Thank you again
Merry Christmas
tim
Hi Tim, the coupling capacitors were always quoted as 100nF in the circuits I saw but there was also this write-up which you may like.
"The coupling capacitor can be chosen to introduce an extra degree of bass roll-off to reduce the amplitude of subsonic signals. At the moment the roll-off is set to -3dB at approximately 10Hz. It is preferred to set the limit to around 10Hz otherwise the bass starts to sound thin and light. A later modification was made to the 3.18uS RIAA time constant correction, by inserting paralleled 75k and 18k resistors on left and right channels."
Hope that helps Tim, feel free to play around with values, every conversion I have done has been swept 20Hz to 20kHz and all follow the RIAA well. That to me was the target and any wanted variation in EQ should be done by an in-line pre-amp/Tone stage though for me running Flat is fine. It certainly shows up the poorly mastered vinyl that was often shoved out quick for the Teenagers "Dansette" Record Player days of the 60's.
The WAD circuit does what was required in getting something good out of a poorly performing unit and there is nothing stopping you using any another RIAA amplifier circuit, originally I intended to show what I had done to my MS22b. But then a lot of others have tried the same conversion and are so so happy they did.
My advice for the MS12 is to use the rear two double Triodes as cathode followers, put the LesBox arrangement into the RIAA stages, dump the Transistors and wire to one of the double Triodes. Link the CD inputs to the other double Triode with perhaps a resistive attenuator if the CD output is too large, i.e. adjusted for approximate equal output to the RIAA one. You can use the Relay to select which output you want fed to the main amp. The heater circuit of that thing really needs sorting out, one should not be using dropper resistors in the heater lines in this day and age. :-D
"The coupling capacitor can be chosen to introduce an extra degree of bass roll-off to reduce the amplitude of subsonic signals. At the moment the roll-off is set to -3dB at approximately 10Hz. It is preferred to set the limit to around 10Hz otherwise the bass starts to sound thin and light. A later modification was made to the 3.18uS RIAA time constant correction, by inserting paralleled 75k and 18k resistors on left and right channels."
Hope that helps Tim, feel free to play around with values, every conversion I have done has been swept 20Hz to 20kHz and all follow the RIAA well. That to me was the target and any wanted variation in EQ should be done by an in-line pre-amp/Tone stage though for me running Flat is fine. It certainly shows up the poorly mastered vinyl that was often shoved out quick for the Teenagers "Dansette" Record Player days of the 60's.
The WAD circuit does what was required in getting something good out of a poorly performing unit and there is nothing stopping you using any another RIAA amplifier circuit, originally I intended to show what I had done to my MS22b. But then a lot of others have tried the same conversion and are so so happy they did.
My advice for the MS12 is to use the rear two double Triodes as cathode followers, put the LesBox arrangement into the RIAA stages, dump the Transistors and wire to one of the double Triodes. Link the CD inputs to the other double Triode with perhaps a resistive attenuator if the CD output is too large, i.e. adjusted for approximate equal output to the RIAA one. You can use the Relay to select which output you want fed to the main amp. The heater circuit of that thing really needs sorting out, one should not be using dropper resistors in the heater lines in this day and age. :-D
OK Tim but I cannot recommend more the 3rd valve option. Even I, as seasoned electronics engineer of nearly 60 years, could not believe there would be such a difference between solid state and valve in a simple arrangement such as a source/cathode follower. The difference expected was minimal but in practice the valve won due to the loss of "air", for want of a better word, when a Mosfet was used. Looking back, it might be advantageous to get a Mosfet with the lowest input capacitance, maybe that is where I went wrong with the ones I used which just happened to be at hand. Good Luck Tim.
Just checked the LND150, it is a Depletion Mode FET whereas the BUZ80 is an Enhancement Mode FET. Never tried the Depletion Mode devices in the circuit so you may have to make some changes.
Just checked the LND150, it is a Depletion Mode FET whereas the BUZ80 is an Enhancement Mode FET. Never tried the Depletion Mode devices in the circuit so you may have to make some changes.
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Hi. Just completed your WAD mod to my '23B. Sounds awesome! Great job getting this sorted. When I did mine I had reserves regarding hard wiring the V3 in and possible later access to the PCB. I mounted my V3 socket from the PCB side of the case using M3 screws and a lock nut/washer so the top nut can be un-done for PCB removal. The V3 socket can be pushed below the surface of the case and the PCB slid out with the socket still attached. Works well. Also I had room to mount the 200pF EQ's on the component side of the board next to the 3.3uF caps. Anyway, GREAT mod and recommend to anyone wanting more from thier pre-amp. Thanks so much and best regards.
Well I finally found the opportunity to convert a MS12b.
I dispensed with the silly 12AU7 15 Ohm filament dropping resistor but changed it to 8R2 at 7W and placed it in series with the regulator. By doing this, I was able to run all 4 valves and the relay circuit direct from the present 12V regulator. The 8R2 acts as a ballast for the regulator and takes away unnecessary dissipation in the regulator, this I lifted with the usual diode to give a nice 12.5V
The big decision to make was how to replace the transistor buffer in the RIAA circuit with one of the present valves. I decided to move the relay such that it now steered the RIAA into a single buffer valve, or it steered the CD/DVD preamp to the same buffer. All this has to be done at HT (B+) voltages instead of low level and the preamp still needed a volume control to protect its input from overload. Thus the RIAA output no longer see the volume control, something that is not really needed anyway.
Only problem is the very large thump when switching the relay but not a problem if the main amp volume is turned down prior to switching, or even switching the main amp to one of its unused inputs. View the pdf yourself and you will see it involves a lot of work but at least you don't need to cut another hole for a 5th valve. There would be no room for this anyway which is why a compromise had to be reached. Needless to say, the owner is delighted with the results.
http://homepage.ntlworld.com/lez/Yaqin MS-22B/Putting 'Life' into the Yaqin MS-12B.pdf
I dispensed with the silly 12AU7 15 Ohm filament dropping resistor but changed it to 8R2 at 7W and placed it in series with the regulator. By doing this, I was able to run all 4 valves and the relay circuit direct from the present 12V regulator. The 8R2 acts as a ballast for the regulator and takes away unnecessary dissipation in the regulator, this I lifted with the usual diode to give a nice 12.5V
The big decision to make was how to replace the transistor buffer in the RIAA circuit with one of the present valves. I decided to move the relay such that it now steered the RIAA into a single buffer valve, or it steered the CD/DVD preamp to the same buffer. All this has to be done at HT (B+) voltages instead of low level and the preamp still needed a volume control to protect its input from overload. Thus the RIAA output no longer see the volume control, something that is not really needed anyway.
Only problem is the very large thump when switching the relay but not a problem if the main amp volume is turned down prior to switching, or even switching the main amp to one of its unused inputs. View the pdf yourself and you will see it involves a lot of work but at least you don't need to cut another hole for a 5th valve. There would be no room for this anyway which is why a compromise had to be reached. Needless to say, the owner is delighted with the results.
http://homepage.ntlworld.com/lez/Yaqin MS-22B/Putting 'Life' into the Yaqin MS-12B.pdf
Hello All
On page 26 of the MS-22B mod PDF I see a +6db gain switch I am assuming this will increase output to the pre-amp or amp being used, is this correct?
Also is any member using a LESMOD with a passive preamp and having success? I have a stock version and with a Jolida JD5T and in order to get the volume up I am at 3/4 way or more.
I am currently talking with Les regarding the mod but would like to know if the low gain from the MS22B is any better when using the passive jolida pre or if I am better off getting another phono pre-amp like the JD9.
On page 26 of the MS-22B mod PDF I see a +6db gain switch I am assuming this will increase output to the pre-amp or amp being used, is this correct?
Also is any member using a LESMOD with a passive preamp and having success? I have a stock version and with a Jolida JD5T and in order to get the volume up I am at 3/4 way or more.
I am currently talking with Les regarding the mod but would like to know if the low gain from the MS22B is any better when using the passive jolida pre or if I am better off getting another phono pre-amp like the JD9.
I'm having an issue with my les box. When I turn it on it creates a small flutter in the speakers. I usually just keep the amp volume down when I first turn it on to avoid this. Once it's powered on it works fine and I don't hear much hum. When I decided to increase the value of the 2.2 caps to 3.3 it creates a constant flutter in the left woofer. Is there something wrong with the ground loop? Could it be that i'm still using 68uf for C15 & C16? Also to my ears it sounds like the channels may be a bit out of phase 
. Any help with this would be greatly appreciated.
. Any help with this would be greatly appreciated.
IF anyone has any Yaqin amp, pre-amp or other cheap-Chinese tube equipment using a Mains Power-Lead supplied with the item, Please heed this warning.
The Mains-Lead Supplied with these appliances is of VERY POOR quality, Is Not Fused and does Not comply with any Safety Testing bodies.
Ditch the original Power-Lead, and use one that has Approvals for your Country. Best cut the original up and dispose of it.
The power-lead does NOT have to be some daft audiofool item costing more than the amp its powering--Just a good quality IEC lead that is fused appropriately.
The Mains-Lead Supplied with these appliances is of VERY POOR quality, Is Not Fused and does Not comply with any Safety Testing bodies.
Ditch the original Power-Lead, and use one that has Approvals for your Country. Best cut the original up and dispose of it.
The power-lead does NOT have to be some daft audiofool item costing more than the amp its powering--Just a good quality IEC lead that is fused appropriately.
Have ordered a Ms23b, purely on the basis of research derived from this forum and the recommendations of the Lesbox rebuild to MS23BLB spec, have my mundorf caps here that arrived today and the complete component list also arrived today courtesy of RS components. I have noted the price of the Svetlana tubes is now $37.67 AUD each so not that the Aussie dollar is a big deal and still cheap compared with tele NOS and 3 are on their way. Unlike our backstabbing treasonous politicians, I expect all in the conversion to go very well after reading and researching. Cant really wait to get started but the Yaqin purchased from the bay will be the last to arrive out of all international orders so now its a waiting game. I am in no way an electronics tech so as mentioned by Alastair E, I will replace the power lead Can i run a fuse in line too? If that's not a NUBE question what is???? If there are anymore new info on this amp and its conversion please tell, I know its well over a year since the creation of this thread, i will update as i go. Cheers to Les for the opportunity to create something from an unreliable junk circuit at least China has provided a cheap foundation and some fun for those into DIY. Have not ordered the sockets yet for V3 but is it worth replacing the 2 existing? Is it critical to shield high gain 12ax7 tubes? How high are the brass mounts for the existing sockets? Is it possible to mount V3 in the same fashion as the existing tubes but on higher brass mounts secured to the pcb? reason for the lame questions is i want all the components ready for the project to go before it arrives, for me preparation is 3/4 of the job.
Hello all! New to the world of tubes and valves. I have just received a brand new MS-23B and would like to start on the LesBox conversion. Right now, I am gathering all the required components. It seems that the Lemco 8200pF is rather hard to find. Can I use any other replacement of the same values?
Happy New Year all.
Well, I've been thoroughly enjoying my LesBox for some time now, but a problem has arisen. It's suddenly developed a hum on both channels. I've changed leads, valves and TT, but still a hum. Have also run through the test list and everything is withi parameters. It sounds like an earth hum but it does not change tone or volume when metal is touched. I'm thinking maybe a component has failedmaybe? But where to start....any clues please?
Well, I've been thoroughly enjoying my LesBox for some time now, but a problem has arisen. It's suddenly developed a hum on both channels. I've changed leads, valves and TT, but still a hum. Have also run through the test list and everything is withi parameters. It sounds like an earth hum but it does not change tone or volume when metal is touched. I'm thinking maybe a component has failedmaybe? But where to start....any clues please?