does anybody have any experience with this fantastic monster of an amp i've just bought? i could've sworn i was glancing at a discussion about modding this amp on one of my countless nights of insomnia binge. would've bookmarked the page if i knew i was gonna end up spending the money i can't afford on it. the bass on this amp is more terrifying than the nad 2200 i used to own- no small feat when compared to a 400w per channel SS. and when the triode mode is flipped on, oh gosh, it's like wearing a weightless headphone- the music just emanates from inside my head. totally transparent. but eherm, excuse my rambling and please share with me your info.
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Mods on MC34AB
Yes... I have owned this amp for several months now and have done quite a few mods to it...all with great success. First... throw out the 12AU7s that came with the unit and replace them with Tele 12ax7s or some good quality tube.
Next... Replace ALL the coupling and bypass caps in the unit with Vitamin Q or Russian K40, K42 units. Most of the caps in the amp are fakes....in fact even some of the names on them are spelled wrong! It's a pain to try to stuff in 8 1 or 2uf pio caps in the unit, but it can be done...and it comes out rather neatly if you take your time. I also eliminated my aux input and installed a preamp output for my sub, but as it turned out the unit is so good now I don't need it! Also....check to make sure no ChemiCon power supply caps were used in the unit. None were in mine, but if you see them....change them out for Nichocan or Panasonics from Digikey.
Next I swapped out the blue bottled EL34s for an octet of Gold Lion Reissue KT-66s. The difference was almost as dramatic as the PIO cap changes. ( The gold lions have the tapered bottoms so you don't have to remove the chrome beauty rings around the stock Ming Da sockets. If you want to run KT-88s, you can, but you'll need to purchase some inexpensive "socket savers" for octal tunes.....about $5 each on eBay to space the tubes up an inch or so to clear the beauty rings.)
The unit now sounds better than my original setup which was a Mac275 Reissue with an Audio Research LS25 Mk2 driving it. I'm using Altec Lansing model 19 speakers and alternate between them and Klipsch Cornwalls with the older motor run caps for crossovers.
This is an awesome unit!! The build quality is excellent. It's built like a tank and has the sweetest sound I've heard in years....with bottom end slam that almost equals my McShane modded Citation 2s. If you get a chance to get one of these....do it! Make the mods....leave the light bulb 6SN7s. I tried 16 or 17 other NOS units in their place and couldn't find an equal. For me...this is a keeper and at the $800 I got it for brand new on eBay...( plus $300 shipping), it can't be beat. It's outplaying a $10,000 system!
Yes... I have owned this amp for several months now and have done quite a few mods to it...all with great success. First... throw out the 12AU7s that came with the unit and replace them with Tele 12ax7s or some good quality tube.
Next... Replace ALL the coupling and bypass caps in the unit with Vitamin Q or Russian K40, K42 units. Most of the caps in the amp are fakes....in fact even some of the names on them are spelled wrong! It's a pain to try to stuff in 8 1 or 2uf pio caps in the unit, but it can be done...and it comes out rather neatly if you take your time. I also eliminated my aux input and installed a preamp output for my sub, but as it turned out the unit is so good now I don't need it! Also....check to make sure no ChemiCon power supply caps were used in the unit. None were in mine, but if you see them....change them out for Nichocan or Panasonics from Digikey.
Next I swapped out the blue bottled EL34s for an octet of Gold Lion Reissue KT-66s. The difference was almost as dramatic as the PIO cap changes. ( The gold lions have the tapered bottoms so you don't have to remove the chrome beauty rings around the stock Ming Da sockets. If you want to run KT-88s, you can, but you'll need to purchase some inexpensive "socket savers" for octal tunes.....about $5 each on eBay to space the tubes up an inch or so to clear the beauty rings.)
The unit now sounds better than my original setup which was a Mac275 Reissue with an Audio Research LS25 Mk2 driving it. I'm using Altec Lansing model 19 speakers and alternate between them and Klipsch Cornwalls with the older motor run caps for crossovers.
This is an awesome unit!! The build quality is excellent. It's built like a tank and has the sweetest sound I've heard in years....with bottom end slam that almost equals my McShane modded Citation 2s. If you get a chance to get one of these....do it! Make the mods....leave the light bulb 6SN7s. I tried 16 or 17 other NOS units in their place and couldn't find an equal. For me...this is a keeper and at the $800 I got it for brand new on eBay...( plus $300 shipping), it can't be beat. It's outplaying a $10,000 system!
To do this properly the plate and cathode resistors would have to be replaced so that the 12AX7 will bias correctly and be properly loaded. To just replace the 12AU7 with a 12AX7 would load the 12AX7 with way to little plate resistance and will result in gross 2nd harmonic distortion. Further, the gain of the 12AU7 is way less than the 12AX7 so the following stage will have to be modified so as not to overdrive it. So what we are really talking about is an re-engineering of the first couple of stages. Many here can do that easily; if you aren't one of them, I would stick with a good 12AU7 variety, say an Amperex 7316.
That is not to say that anything will blow up or won't work with the tube type swap. It just means that the 12AX7 will badly distort and overdrive the next stage. Of course, you may LIKE extreme 2nd harmonic distortion in which case have at it....
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I tried a number of other 12AU7s in it's place before the teles went in. The Chinese 12AU7 that they use is either NOT a 12AU7 or it is grossly out of range for that type tube. I tried Bugle Boys, 5963s and a number of like type tubes......all of which resulted in a much lower and noticeable volume loss.....hence my step up to a tube with more gain. I have not measured the Chinese version on a tube tester yet to see what it actually is, but it's NOT a run of the mill 12AU7.
In answer to one of the above statements.... I've been working with tube gear and building my own amps since I was 14....and that was in 1960. I believe I could handle rewiring a single stage...and if the tube in question required that I would certainly have done it. Thank you for the heads up though.
Sorry... I think I mislead you or didn't state the situation as I should have. What I meant to indicate is that even though these Chinese tubes were marked as 12AU7s, they are, in fact, not. Every 12AU7 that was rolled into this amp cut the volume by more than 50%. I believe that the amp actually calls for a 12AX7 in it, regardless of what they tubes were marked as. I also did try them in another amp that actually needs 12AU7s and yes indeed....the distortion was obvious. I put them into another amp that wanted 12AX7s and they worked out just fine...despite the fact that they had the audio quaility of a $2 Chinese tube!
The whole point to this post was simply to point out to the buyer of the unit that it is indeed a wonderful piece of equipment and lends itself to simple mods quite easily. I'm not pursuing this amp to mod anymore than I have already...it's quite adequate for it's purpose and surpasses all other imports that I've tried in the past.
I'm not much into imports... I deal mainly with old Macs, Heathkit W6Ms, and primarily Citation 2s which once modded are quite possibly my favorite amp with the exception of the W6s which have also been Mcshane type modded and have mostly PIO caps in them. Huge Perless transformers with a power transformer the size of a Citation 2 power transformer for each unit lends itself to some extraordinary sound...provided you can find space for them on your shelf and with 5 or more times the power supply capacitance you can imagine that they never whimper at all even under extreme loads.
Again though....even though I prefer vintage gear which will always hold it's value and certainly increase in time, for everyday listening and if you're not concerned with trying to make a profit on the unit, the Ming Da is an excellent investment.
The whole point to this post was simply to point out to the buyer of the unit that it is indeed a wonderful piece of equipment and lends itself to simple mods quite easily. I'm not pursuing this amp to mod anymore than I have already...it's quite adequate for it's purpose and surpasses all other imports that I've tried in the past.
I'm not much into imports... I deal mainly with old Macs, Heathkit W6Ms, and primarily Citation 2s which once modded are quite possibly my favorite amp with the exception of the W6s which have also been Mcshane type modded and have mostly PIO caps in them. Huge Perless transformers with a power transformer the size of a Citation 2 power transformer for each unit lends itself to some extraordinary sound...provided you can find space for them on your shelf and with 5 or more times the power supply capacitance you can imagine that they never whimper at all even under extreme loads.
Again though....even though I prefer vintage gear which will always hold it's value and certainly increase in time, for everyday listening and if you're not concerned with trying to make a profit on the unit, the Ming Da is an excellent investment.
New MC34-AB
Hi,
This has been a great forum and I really appreciate the suggestions.
I received the Ming Da MC34-AB several weeks ago from Cattylink. Their email response, customer service, and shipping was excellent.
So far below are changes I have made:
*tube changes: Genalex KT66, Mullard 12AT7, kept the stock onion shaped tubes.
*Cap changes: replaced all 12 of the "Ming Da" white caps with Jantsen silver.
I am very impressed with the sound. The mids and highs are very clean and extended. The soundstage is very deep and 3D (almost as good as my Welborne 300B Terraplanes).
The bass is well extended.
There is one concern the first two seconds when I turn the unit on. The two
12AT7 tubes light up like a light bulb. The tubes then dim back to a more normal brightness. I am afraid this will greatly reduce the life of the tubes. Is there anything I can do to add a "soft start".
Thanks,
Jim
Hi,
This has been a great forum and I really appreciate the suggestions.
I received the Ming Da MC34-AB several weeks ago from Cattylink. Their email response, customer service, and shipping was excellent.
So far below are changes I have made:
*tube changes: Genalex KT66, Mullard 12AT7, kept the stock onion shaped tubes.
*Cap changes: replaced all 12 of the "Ming Da" white caps with Jantsen silver.
I am very impressed with the sound. The mids and highs are very clean and extended. The soundstage is very deep and 3D (almost as good as my Welborne 300B Terraplanes).
The bass is well extended.
There is one concern the first two seconds when I turn the unit on. The two
12AT7 tubes light up like a light bulb. The tubes then dim back to a more normal brightness. I am afraid this will greatly reduce the life of the tubes. Is there anything I can do to add a "soft start".
Thanks,
Jim
As stated above the bright light for the Mullards is common. It happens in Macs as well....not to worry. The build quality on the unit could be better....sure....it's typical Chinese with main busses and everything else attached to them, but it's laid out well and pretty solid....better than most. Rebias the KT66s though....they'll take quite a bit more than the EL34s and you'll hear the difference.
Thanks for the reply.
I have not seen my other tube equipment behave like the Mullards.
My experience with Ming Da is with the MC-2A3 preamp where I made significant mods including a minor circuit change, many new caps, Goldpoint stepped attenuator, and input switch. After the mods the sound is amazing and clearly is a significant improvement on my DIY Welborne Ultrapath BP. It has been compared to very expensive pre-amps (up to 10k cost) and in most cases the modified MC-2A3 was preferred.
Overall build and part quality of the MC-2A3 AND mc34-AB are excellent. They do seem to skimp on the capacitors and selector switches, however. The point to point wiring and chassis is as good as I have seen. Apparantly the massive transformers come from Japan.
Thanks again,
Jim
I have not seen my other tube equipment behave like the Mullards.
My experience with Ming Da is with the MC-2A3 preamp where I made significant mods including a minor circuit change, many new caps, Goldpoint stepped attenuator, and input switch. After the mods the sound is amazing and clearly is a significant improvement on my DIY Welborne Ultrapath BP. It has been compared to very expensive pre-amps (up to 10k cost) and in most cases the modified MC-2A3 was preferred.
Overall build and part quality of the MC-2A3 AND mc34-AB are excellent. They do seem to skimp on the capacitors and selector switches, however. The point to point wiring and chassis is as good as I have seen. Apparantly the massive transformers come from Japan.
Thanks again,
Jim
I also have the same preamp with extensive mods done by a friend named Johnson who has posted the mods on a webpage. He has extensive experience with this particular preamp.Many of the electrolytics were replaced with Valab poly 30uf caps, the regulator stages were completely modified and a pair of 2uf PIO caps used for the output caps. It's an amazing sounding preamp.
The transformers are actually made by Ming Da which started out as a transformer company before they began to build their own equipment. They are of outstanding quality.
The transformers are actually made by Ming Da which started out as a transformer company before they began to build their own equipment. They are of outstanding quality.
I used the mods posted from Johnson. He was very helpful with email responses when I had a few questions regarding the small circuit change. The electrolytics replacement was slightly different using additional Valab caps. The output caps are M-caps silver/oil.
The MC34-AB visually matches the MC-2A3 preamp very well with a similar footprint and layout.
Thanks,
Jim
The MC34-AB visually matches the MC-2A3 preamp very well with a similar footprint and layout.
Thanks,
Jim
I purchased my preamp from a fellow who lives near Johnson at a great price, but he didn't want to ship it. Johnson was kind enough to pick it up for me, do all the mods himself and all I did was send him some 2uf Vitamin Q PIOs and several other parts to assist in the operation so Johnson didn't have to order everything for it. 90% of the parts he either had already or ordered. He have talked on the phone on many occasions and he stated that this unit was the best he had ever heard...including his own. I have to agree....it outperforms my AR LS25 Mk2 and even my Reference 1 for realism in sound and sound stage. I was thrilled with the work he did and his wiring and mounting of parts is extraordinarily clean and professional. The man does beautiful work and was also very helpful with the mods on the MC34 as well. Quite a nice fellow and looking for more of these to do if anyone wants one modded to it's fullest capability. He knows them inside and out. When he finished mine he had a concert pianist come to his house and audition three high end preamps back to back of which mine was one, but unknown to the musician. The musician immediately chose mine as the most natural and best sounding of the three. I'll be keeping this one!
Granted.....speaker systems and the power amp make a considerable difference with different preamps as we all know. I use this one with a level 2 plus McShane modded Citation 2 and a pair of very high efficiency Altec Lansing model 19s with the large horns. I couldn't be happier with the sound.
Granted.....speaker systems and the power amp make a considerable difference with different preamps as we all know. I use this one with a level 2 plus McShane modded Citation 2 and a pair of very high efficiency Altec Lansing model 19s with the large horns. I couldn't be happier with the sound.
It sounds like you have a great system.
In my main audio room I use the MC-2A3 and MC34-AB with some used B&W N802 speakers. In my living room I run diy Welborne 300B Terraplane monoblocks with diy open baffle speakers using Supravox 215 EXC 8" field coil drivers, 15" Hawthorne Augie woofers and fountek ribbon supertweeters (10K and above crossed over).
So far on the MC34-AB I have only replaced the 12 Ming Da brand caps and the tubes.
Do you have any suggestions for further mods?
Thanks,
Jim
In my main audio room I use the MC-2A3 and MC34-AB with some used B&W N802 speakers. In my living room I run diy Welborne 300B Terraplane monoblocks with diy open baffle speakers using Supravox 215 EXC 8" field coil drivers, 15" Hawthorne Augie woofers and fountek ribbon supertweeters (10K and above crossed over).
So far on the MC34-AB I have only replaced the 12 Ming Da brand caps and the tubes.
Do you have any suggestions for further mods?
Thanks,
Jim
Hi Jim.... Nice setup! I'm using the MC34 with a preamp from Audio8 on eBay.... He calls it a line stage SP10 copy and although it's a very nice sounding preamp out of the box I did the same with it.....replaced all the caps with PIOs including 8 2UF pios just for the output stage. Why he would want 8uf for each channel beats me, but it's a dual mono preamp with highly regulated dual power supplies and sounds quite nice. I'm using an old Dynaco tube CD player through a Cambridge Dac Magic and driving some old SDA SRS Polk series 1 speakers. It's a bit of a struggle for the amp, but still sounds great. The speakers have been sold, but I wanted to hear what they sounded like with the setup. I normally use Cornwalls with the early motor run cap crossovers in them. The MC34 drives the living you know what out of them! I recently stopped using my Terra Dac Chameleon from eBay DIY and switched to a Logitech Touch server and purchased the Duet remote for it so that both the unit and the remote have the color display on them. I found out purely by accident that the built in DAC in the Logitech sounds every bit as good as the $500 Terra Dac. I was shocked since the Tera Dac has about 15 Burr Brown chips in parallel in it and is quite a good unit with a separate power supply for it. I still use it for the MHZS 60 CD player, but have almost completely stopped with the CDs and mostly use the Touch....it's convenient, connects directly to Rhapsody where I have an account and I can download lossless and play at the same time. I guess age is catching up with me and convenience is beginning to take over!
I'd love to try some ribbons at some point, but my HF hearing is diminishing as I get older...hence the horns with the Altecs. They still allow me to hear as much as I can although others around me must hate it, having to turn up the crossover level on the horns to be able to appreciate many of the high mids and highs in music, but since I generally am alone when I listen I guess it doesn't matter too much. Mikey Samra ( another member here and a good friend) keeps wanting me to try out some Maggies, but I can't really afford them and probably wouldn't be able to enjoy them like many do. I envy you being able to use the ribbons and actually be able to hear them!
I've tried a few low power single ended amps before, but I guess I'm old school and of the feeling that "heavy iron" is the only way to travel. Big Peerless transformers and at least a pair of K-88s per channel. My Heath W-6s are running the Tungsol KT120s and although they don't have the quality of sound that original EI KT-90s do or Winged C 6550s, they do put out the ponies and I'm beginning to acquire a better taste for them. They grow on you after a while....or perhaps they just need a good break in period.
I can't think of much else you can do with the MC34 to improve on it aside from replacing all the output caps and bypass caps with good quality PIOs or otherwise. I used Vitamin Qs and Dearborns for the smaller cap values and Russian K40 Y-9s for the output caps. They were the only ones small enough (physically) to fit into the unit without having things hanging all over the place. They tucked in quite nicely although tightly and after 50 or so hours of play time are just beginning to smooth out. They were a bit too crisp at first. Also, Johnson suggested a simple feedback loop to increase the bottom end slightly and a resistor change to drop the sensitivity of the input. Mine was a little too high from the factory and on a scope I could see that it was picking up some slight noise. The change eliminated it. I don't think I still have his email from the mod, but I'm sure he would remember it. He also had a few ideas about better regulation with the unit, but I was more than happy with it at that point so I never incorporated any of them. He could help with that though....he has the schematics for both units. I think what you've done is more than adequate though and if you'll look at what Pacfic charges for thier "super mods" from some outside company it's ridiculous. They've done virtually nothing to the unit aside from a Black Shugang tube change and although they state that they have "special caps" from Ming Da, they're the exact ones that mine came with....cheap little featherweight 1 or 2uf caps that are the size of a .005 cap of any quality! It's disappointing that Ming Da could have spent another $20 or so in parts when building these and deliver them with a quality that would command almost twice the price very easily....and yet didn't. The resistors are of excellent quality...they simply skimped on a few caps. It's not that I mind making the changes, but it would have been so easy for them to do it at the factory and really boost their quality and sales....at least in my opinion. On the other hand it gives us something to do and to play with....and the improvement in sound (which was already excellent) is remarkable.
Regards,
Bill
I'd love to try some ribbons at some point, but my HF hearing is diminishing as I get older...hence the horns with the Altecs. They still allow me to hear as much as I can although others around me must hate it, having to turn up the crossover level on the horns to be able to appreciate many of the high mids and highs in music, but since I generally am alone when I listen I guess it doesn't matter too much. Mikey Samra ( another member here and a good friend) keeps wanting me to try out some Maggies, but I can't really afford them and probably wouldn't be able to enjoy them like many do. I envy you being able to use the ribbons and actually be able to hear them!
I've tried a few low power single ended amps before, but I guess I'm old school and of the feeling that "heavy iron" is the only way to travel. Big Peerless transformers and at least a pair of K-88s per channel. My Heath W-6s are running the Tungsol KT120s and although they don't have the quality of sound that original EI KT-90s do or Winged C 6550s, they do put out the ponies and I'm beginning to acquire a better taste for them. They grow on you after a while....or perhaps they just need a good break in period.
I can't think of much else you can do with the MC34 to improve on it aside from replacing all the output caps and bypass caps with good quality PIOs or otherwise. I used Vitamin Qs and Dearborns for the smaller cap values and Russian K40 Y-9s for the output caps. They were the only ones small enough (physically) to fit into the unit without having things hanging all over the place. They tucked in quite nicely although tightly and after 50 or so hours of play time are just beginning to smooth out. They were a bit too crisp at first. Also, Johnson suggested a simple feedback loop to increase the bottom end slightly and a resistor change to drop the sensitivity of the input. Mine was a little too high from the factory and on a scope I could see that it was picking up some slight noise. The change eliminated it. I don't think I still have his email from the mod, but I'm sure he would remember it. He also had a few ideas about better regulation with the unit, but I was more than happy with it at that point so I never incorporated any of them. He could help with that though....he has the schematics for both units. I think what you've done is more than adequate though and if you'll look at what Pacfic charges for thier "super mods" from some outside company it's ridiculous. They've done virtually nothing to the unit aside from a Black Shugang tube change and although they state that they have "special caps" from Ming Da, they're the exact ones that mine came with....cheap little featherweight 1 or 2uf caps that are the size of a .005 cap of any quality! It's disappointing that Ming Da could have spent another $20 or so in parts when building these and deliver them with a quality that would command almost twice the price very easily....and yet didn't. The resistors are of excellent quality...they simply skimped on a few caps. It's not that I mind making the changes, but it would have been so easy for them to do it at the factory and really boost their quality and sales....at least in my opinion. On the other hand it gives us something to do and to play with....and the improvement in sound (which was already excellent) is remarkable.
Regards,
Bill
Hi Bill,
I sometimes use the Logitech Duet and am very impressed with the sound as well. I bypass the Logitech dac and plug the optical cable directly to my Arcam home theater amp. Most of the time I listen to vinyl though.
My brother used to be the Supravox US distributor and he has huge "big fun horns" with the 215 Exc 8" field coil drivers. The sound is amazing with quite extended bass. He also uses ribbon supertweeters crossed over first order at 10Khz.
Thanks for info about the MC34. I'll probably leave it as is for now as it sounds great.
Jim
I sometimes use the Logitech Duet and am very impressed with the sound as well. I bypass the Logitech dac and plug the optical cable directly to my Arcam home theater amp. Most of the time I listen to vinyl though.
My brother used to be the Supravox US distributor and he has huge "big fun horns" with the 215 Exc 8" field coil drivers. The sound is amazing with quite extended bass. He also uses ribbon supertweeters crossed over first order at 10Khz.
Thanks for info about the MC34. I'll probably leave it as is for now as it sounds great.
Jim
I'm beginning to see more and more people using the Duet and the Touch. I don't know if the DAC is the same in the two units....the Duet is a much smaller sized unit, but perhaps it's just the Screen on the Touch that makes it larger. I'll have to look into the DAC inside though. I have a Duet as well, but don't use it in favor of the Touch. but hate the little remote on the Touch so I use the Duet remote. Logitech was kind enough to "walk" me through matching up the one remote with the other unit and it worked out quite well.
I've never gotten into the theater systems, but have heard some quite nice ones. Old fashioned I guess.....or maybe just don't want to get that financially involved with it, but I'm happy with a clean sounding old fashioned stereo!
I think you're right about the MC34. You've made the major changes that seem to make the most improvement. No point in overdoing it for perhaps only a slight amount of gain. They sound great as is...and even better with just the simple mods!
Best to you,
Bill
I've never gotten into the theater systems, but have heard some quite nice ones. Old fashioned I guess.....or maybe just don't want to get that financially involved with it, but I'm happy with a clean sounding old fashioned stereo!
I think you're right about the MC34. You've made the major changes that seem to make the most improvement. No point in overdoing it for perhaps only a slight amount of gain. They sound great as is...and even better with just the simple mods!
Best to you,
Bill
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