I asked numerous people associated with this sort of thing ( phono amplifier design/service )how much capacitance I should figure is included in the LesBox circuit for purposes of loading my phono cartridge. After looking at the LesBox schematic nearly all suggest, very little. Most all concluded less than 50pf and some thought less than 25pf.
Yikes! Don't adjust C3/C10 as they are not part of the cartridge loading. On my very first construction (die cast box model) I fitted a 100pF across R1/R12 but I did not bother with the MS22LB as the Yaqin wiring probably adds this. If I could get hold of some of the 2 pin sockets they used, I would probably re-wire with low loss coax cable as at present the fairly long run from the rear plate to the board is unscreened.
What you need to do, if you want to add cartridge load capacitance, is to get hold of a capacitance meter to find the capacitance in the arm wiring (cartridge unplugged) not forgetting to subtract the capacitance of the testers leads. Then measure in the same way the input capacitance at each RCA input Jack. Add the figures obtained and see if they match the capacitance recommended by the cartridge manufacturer. You can than add fixed capacitance across the 47k resistors R1/R17. It's not high precision but will give you some idea of how things are.
What you need to do, if you want to add cartridge load capacitance, is to get hold of a capacitance meter to find the capacitance in the arm wiring (cartridge unplugged) not forgetting to subtract the capacitance of the testers leads. Then measure in the same way the input capacitance at each RCA input Jack. Add the figures obtained and see if they match the capacitance recommended by the cartridge manufacturer. You can than add fixed capacitance across the 47k resistors R1/R17. It's not high precision but will give you some idea of how things are.
I went back to buy a more suitable resistor, and noticed that the one I had purchased said 1/2W 'rated to 1W' - is it safe to use these in that case?
CCF60150KFKE36 Vishay / Dale | Mouser
CCF60150KFKE36 Vishay / Dale | Mouser
I'd said earlier I didn't think I could pull off the Les Box mod myself, but it was going to be a while before I could get to the post office and I couldn't take the temptation with the parts just sitting there. I had to try.
It took me around 30 hours over the last 3 or 4 days, but I finished it and it sounds incredible.
For what it's worth, I used these Dayton 3.3uF precision audio caps in C4 and C12, these Nichicons in C2 and C9, and Tung Sol reissue 12AX7 tubes in all three slots. My system is a Pioneer PL-630 TT with an Audio-Technica AT155LC cartridge > Yaqin 22b Les Box > fully re-capped Pioneer SA-9500 amp > Sony SS-M3 speakers.
The first album I spun after I performed all the tests and everything checked out OK was J.J. Cale and Eric Clapton - The Road to Escondido. It's a super nice pressing and an incredible recording.
I can't say enough about how great it sounds. Tight, powerful bass, crystal clear mids and highs with no distortion, tons of separation and imaging, and a deep, wide soundstage. I'm really, really pleased.
Thanks a million for taking the time to come up with this modification, document the steps so concisely, and then share it with us for free. You're a legend, Les.
It took me around 30 hours over the last 3 or 4 days, but I finished it and it sounds incredible.
For what it's worth, I used these Dayton 3.3uF precision audio caps in C4 and C12, these Nichicons in C2 and C9, and Tung Sol reissue 12AX7 tubes in all three slots. My system is a Pioneer PL-630 TT with an Audio-Technica AT155LC cartridge > Yaqin 22b Les Box > fully re-capped Pioneer SA-9500 amp > Sony SS-M3 speakers.
The first album I spun after I performed all the tests and everything checked out OK was J.J. Cale and Eric Clapton - The Road to Escondido. It's a super nice pressing and an incredible recording.
I can't say enough about how great it sounds. Tight, powerful bass, crystal clear mids and highs with no distortion, tons of separation and imaging, and a deep, wide soundstage. I'm really, really pleased.
Thanks a million for taking the time to come up with this modification, document the steps so concisely, and then share it with us for free. You're a legend, Les.
That's great news! The 1/2W is OK, I specified 1W for ultra reliability :-D
In fact a 1/3W would probably do but not much extra margin. It's good that you already knew how the stock unit sounded so that you appreciate the difference. It's crazy but people are sending me units direct from Hong Kong without hearing the stock. I am having problems with customs at the moment as they want to charge me a lot of $ even though they are going straight out of the country after a few days. BTW Those capacitors look good for the price - amazing.
In fact a 1/3W would probably do but not much extra margin. It's good that you already knew how the stock unit sounded so that you appreciate the difference. It's crazy but people are sending me units direct from Hong Kong without hearing the stock. I am having problems with customs at the moment as they want to charge me a lot of $ even though they are going straight out of the country after a few days. BTW Those capacitors look good for the price - amazing.
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Hi all. 1st post here. I've finally unpacked my vinyl after 8 years Down Under! I'm in the process of renovating (degreasing etc) the Garrard AP76 my Dad bought new way back when. A marvellous piece I think. Will be going along the AT120E road eventually..probably... I've had one of these Yaqin MS 23B's in my watch list for a while now and stumbled across this thread while researching it. I'm sold by the Les Box upgrade and plan to get things moving very soon. I worked, briefly for Audio Innovations back in Brighton in the 80's so I feel confident to revisit the solder sucker and iron. For the time being, the MS 23 B will be running into a very ordinary Akai AA-R21L (yes, I know...). My question is regarding the output from the Yaqin (the ad says 500mV, 400Hz - does this remain the same after the 3 tube upgrade?). The Akai's input on the aux is 150mV/47kohms so would I need some kind of attenuator or would I be ok? My knowledge is limited by being at AI only 6 weeks before they decided to relocate to the West Country and it being 30 odd years ago. All advice (including berating the Akai 
) is welcome. Thanks.
) is welcome. Thanks.
You should be OK feeding the LesBox into the AUX/TUNER or CD inputs. I doubt if it will overload them as you will hear by clipping and distortion. I have tried feeding it into various amplifiers as well as Tape Decks and even Mini disc decks direct and all have been fine. Please go for the 3 valve version, I think the Mosfet version is really for those with the MS12b but it never makes it quite as good as the 3 valve version. In all of my years as an electronics engineer, I never expected such a difference between a Mosfet and a Valve both being used purely as followers. The only explanation I can offer is perhaps the extra input capacitance of the Mosfet that destroys all the upper end sparkle.
Hi Hi_Q, thanks for your reply confirming what I had quietly hoped for. I will most definately be going for the 3 valve set up - I've been reading your posts and the discussions on the upgrade from around the net and they have inspired me (along with the moderate success of the Garrard restoration) to get 'hands on' again. It will definately take me longer than your 2 nights to do it, and I suspect there may be some tears and frustrations along the way, but hell, I WILL do it! The Svets will be going in I suspect, but I'm going to have a search for my old valve stash and see what I've got there as I don't remember which ECC83's we used in the Audio Innovation's back then.
Would it be rude to ask if you would make up a parts kit of your preferred components which I of course would pay all costs, expenses and shipping for? (not the valves). I've seen the kit offered on the auction site and I'm sure they're all available over here, but I thought it best to ask the designer himself as my knowledge of brands is zero in this field nowadays.
Thanks, Geoff.
Would it be rude to ask if you would make up a parts kit of your preferred components which I of course would pay all costs, expenses and shipping for? (not the valves). I've seen the kit offered on the auction site and I'm sure they're all available over here, but I thought it best to ask the designer himself as my knowledge of brands is zero in this field nowadays.
Thanks, Geoff.
Never considered doing a kit of parts as I assumed that they were all easily available and would probably be cheaper if sourced locally. If there are any parts you cannot get hold of then sure I can supply them, just PM your request. I am just doing a conversion destined for Canada and find I am short of the 8200pF capacitors so it looks like another visit to ebay for some more, I don't keep a large stock here and just buy something like 10 at a time.
Well, the 23 has arrived and on first sight it's a good looking thing! Various parts that my local store doesn't stock are arriving bit by bit including 3 shiny new Svets.and a new work bench.. One question (at the moment..) - on the pdf it states for C15 and C16 to use 2 x 100uF 350v Axials, but the pics below show radials. Before I buy, will either fit or is there a preference?
Ta
Ta
funny it must be an aussie thing thefox100- maybe due to our world cup exit...I started purchasing parts for Les's mod today and had exactly the same question re C15 and C16. I ended up ordering radials but sure someone will confirm.
Really looking forward to doing this upgrade, have just upgraded my TT from a Project Debut Carbon to VPI Traveler. Have had the MS22B for some months now and have been fairly happy with it particularly for the price. I was looking at purchasing a new phono stage but figured I should give this mod a chance first!
Really looking forward to doing this upgrade, have just upgraded my TT from a Project Debut Carbon to VPI Traveler. Have had the MS22B for some months now and have been fairly happy with it particularly for the price. I was looking at purchasing a new phono stage but figured I should give this mod a chance first!
Thanks muzz and lilc. Radials it is then - just looking at the pcb I kind of assumed this. Overthinking it! Don't mention the world cup..my (Eng) lot didn't do too well either. From all accounts, this is going to be a beast of a thing - I too tried it out of the box (briefly) and it didn't sound toooo bad on my old Garrard AP76, but I know enough to see the magic that Les has worked. And yes lilc, this little Yaqin was made for rockin'!
Thanks for pointing out that error, I will correct it. Yes they are radial capacitors but you also want the smaller version, rated 350V the size is 18mm Dia. x 25mm Height.
Some component suppliers only stock the much larger size but you can fit the 68uF which appears to be most readily available with those dimensions. The new take off point for the V3 buffer tube on the other side of the 20k resistors would also appear to be a cure for the LF instability making 68uF acceptable. I have a MS23 waiting for collection at my local post office which I shall get tomorrow, this one has come from Melbourne.
Corrected!
Some component suppliers only stock the much larger size but you can fit the 68uF which appears to be most readily available with those dimensions. The new take off point for the V3 buffer tube on the other side of the 20k resistors would also appear to be a cure for the LF instability making 68uF acceptable. I have a MS23 waiting for collection at my local post office which I shall get tomorrow, this one has come from Melbourne.
Corrected!
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Great work team!
Thanks Les and lilc for pointing out the size restriction of the cap, I had ordered a taller one so was able to rescue that situation just in time.
A couple more questions for those in the know:
1/ The output capacitors - C4 and C12 - I tried to order Dayton Audio from Parts Express as mentioned earlier in the thread for $3.50 each, they wanted ~$50 postage so I won't be doing that. Finally found a local supplier of these types which I would prefer to use anyway, could you advise whether there is a difference between 2.2uF and 3.3uF and also if this item is suitable (it is rated 400v). M-Cap or suggest the best item from this site? What did you end up getting Foxy and where from?
2/ From page 2 of instructions:
Thanks in anticipation of anyone's help - perhaps I should try to intercept the box Les is currently working on, on its way back to Melbourne - but where's the fun in that!!!?
Muz
Thanks Les and lilc for pointing out the size restriction of the cap, I had ordered a taller one so was able to rescue that situation just in time.
A couple more questions for those in the know:
1/ The output capacitors - C4 and C12 - I tried to order Dayton Audio from Parts Express as mentioned earlier in the thread for $3.50 each, they wanted ~$50 postage so I won't be doing that. Finally found a local supplier of these types which I would prefer to use anyway, could you advise whether there is a difference between 2.2uF and 3.3uF and also if this item is suitable (it is rated 400v). M-Cap or suggest the best item from this site? What did you end up getting Foxy and where from?
2/ From page 2 of instructions:
- these items aren't mentioned in the parts list, are they over and above and how much improvement do they offer?
Thanks in anticipation of anyone's help - perhaps I should try to intercept the box Les is currently working on, on its way back to Melbourne - but where's the fun in that!!!?
Muz
If it were me, I would choose the polyester (MKT) coupling capacitors (not unlike the Monacors and Vishays that Les has used) from your supplier.
I found the polypropylene types to be a bit "too much" in my LesBox, overly bright, clinical, in your face, etc... at least in my system.
I imagine there are some who have installed "higher-end" polypropylene, teflon, etc...caps in their LesBox and prefer them, so YMMV.
As far as the 8200pf and 200pf caps, (and maybe Les can chime in and clear some of this up) you can re-use some of the caps from the original Yaqin circuit for these positions, but if I'm not mistaken 1% silver mica types would be prefered.
About the 2.2uf or 3.3uf, I believe the original spec was for a 2.2uf cap but Les used 3uf or 3.3uf because he had them on hand, I'm pretty sure that any of those would work fine.
I found the polypropylene types to be a bit "too much" in my LesBox, overly bright, clinical, in your face, etc... at least in my system.
I imagine there are some who have installed "higher-end" polypropylene, teflon, etc...caps in their LesBox and prefer them, so YMMV.
As far as the 8200pf and 200pf caps, (and maybe Les can chime in and clear some of this up) you can re-use some of the caps from the original Yaqin circuit for these positions, but if I'm not mistaken 1% silver mica types would be prefered.
About the 2.2uf or 3.3uf, I believe the original spec was for a 2.2uf cap but Les used 3uf or 3.3uf because he had them on hand, I'm pretty sure that any of those would work fine.
Muzz-I'm still working my way around the same parts. I'll be paying a visit to Jaycar to see what they have in the way of MKT's and mica's etc. I'm aiming for some quality components too. That $50 shipping from the States is a crime - just for 2 caps? Any info on suppliers other than Jaycar in Au would be welcome.