Ming-Da MC34-B

Discussion in 'Equipment Reviews & Opinions' started by DanTana, Apr 3, 2005.

  1. DanTana

    DanTana Super Member

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    Chinese made equipment suffers from a stigma, they cost less so the perceived quality is also less. I have not found this to be true in this case. Politics aside, the Chinese can do what no other country can right now, sell decent made and good sounding equipment for a fraction of others. The Ming-Da MC34-B falls into the category, inexpensive for a tube amp of this quality, and definitely a very good sounding unit.

    First I want to thank Thor for giving me the opportunity to try this and eventually buy it from him, I wasn't expecting much, except I had seen pictures and knew it looked nice, but I was in for a shock when it came to the sound quality. It arrived in it's factory box and packing and in perfect shape, first thing I immediatly noticed was it's heavy weight. I wasn't expecting something that small to weigh that much. I was very taken with it's good looks, polished stainless steel and black krinkle finish transformer covers and a very thick faceplate. The "pagoda" cover I call it, keeps small hands and fingers away from the hot tubes. The whole amp has a feeling of being well built, solid and heavy feeling, the cover has a thick plexiglass top with air holes drilled and polished trim around the outsides. It press fits into the chassis with rubber grommets to hold it in place. The next thing was to bias the output tubes, removing the bottom plate I found the same quality of material, a fairly thick steel bottom, thicker than what you'd even find in the highest of quality Japanese gear. I was very impressed with what I found next, the internal wiring and component layout, was one of the most intelligently thought out of anything I've seen before. All the wires were twisted together, and every component seems to be used as support for the others. The leads of the resistors, capacitors, diodes, are used as supports for the rest of the circuits, the bias pots and wiring points. All resistors are 1 watt rated except the cathode resistors which are 5 watt rated, the capacitors are Rubycon, SME, Samsung, and the coupling caps are "Ming-Da" brand. The bias pots are easy to get to underneath, one nice feature would of been to place these to access from the outside. After biasing the tubes, it was time to finally listen.

    At first I was very impressed with the sound, nice deep bass, fairly linear extension to the treble. However, I wasn't as impressed with the midrange, it was a little muddy and not as clean as I like. I also noticed that in certain passages, female voices and horns seemed a little harsh and edgy. It had 6L6wxt+ Sovtek tubes and after learning I could put in EL34's that was the next logical step. Installing and rebiasing the EL34's were straight forward, I set the bias to 35ma and began listening again, what a difference!! The midrange was now much cleaner sounding, the bass although not as deep, was very tight and detailed. The highs had a nice extended and smooth sound, but at times I still had that slight hardness and edginess. The driver tubes and preamp tubes were 6N1 and 6N2, both using the same pinouts as the 12AU7, 12AX7 tubes except 6 volt filaments. This limits the available tubes to try in this amp, so I first rewired the preamp socket to 12 volt. This wasn't too difficult, and I purchased two JJ Tesla 12AX7's to try in it.

    Now to try the new tubes, first powered it on to make sure it didn't start smoking or other mistakes, and rechecking the bias it was time to listen again.
    Changing out the 6N2's to the JJ Tesla 12AX7's was the next biggest sound improvement, the hardness was now gone, the midrange more detailed and the highs extended very nicely. The EL34's I had used were the new Russian issued Mullards, I purchased these from Triode Electronics and they arrived very quickly, from the outset I could tell these tubes were winners. The next steps I had taken was two fold, I bought some high voltage metal film capacitors and decided to try these new tubes in triode mode. After wiring these in triode and rebiasing once again, time again to hear the difference.

    Once again, another impressive improvement in the sound quality, in triode mode these new Mullard tubes just seemed "sweeter" sounding, more detailed and the midrange was very clean and natural sounding. The highs seem to be more effortless in it's presentation, and at times certain instruments seem to just float in the air. However, one thing seemed lacking somewhat, and that was just a little more inner detail in the music, now much improved I felt it could do a little better. Now at this point normally listening was a joy, no listener fatigue at all, compared to the out of the box listening sessions, I just wanted to listen to every album over and over again, the amp finally captured what my turntable and cartridge was capable of delivering. Being a perfectionist, I was first considering the new "supertube" 6H30pi that could be a drop in replacement for the 6N1, the 6N1 is not a bad tube by any means, but I also had been reading how the new JJ Tesla ECC99 was an outstanding driver tube, made especially for driving high powered triode tubes like the 300B.

    I made a trip to Triode Electronics next, wanting to buy two 6H30pi's and unfortunately, somebody had just purchased 24 of them and they were sold out. What next...well they had the ECC99 JJ Tesla's and for backup, I also bought two RCA clear top 12AU7's. Now to get home and rewire the driver socket from 6 volt to 12 volt and try the ECC99. This wasn't as drastic as an improvement as changing the preamp from the awful 6N2 to the 12AX7, but the sound seemed to clean up noticably, detail mainly was improved. The linearity of the tube was from deep bass to the treble. This driver tube seem to be much more transparent sounding, making the preamp swaps more noticable. Now it is much easier for me to hear the difference between the EH, JJ and other preamp tubes I've tried. I think these new ECC99's are also a winner. The biggest comment I can make about them, is they just seem cleaner sounding. Subtle details are now more noticable and hearing soft passages are easier, during some listening sessions when a loud instrument might be playing, I can still hear the drummer lightly hitting his cymbal. I tried the RCA clear tops and it's no contest between the ECC99 and them. The JJ's win hands down. The JJ's are that much cleaner sounding and detailed than the RCA's to hear a difference.

    Now anybody buying one of these amps may or may not feel the stock amp would need changing, but at least there is a good enough foundation to work with that allows this kind of tweaking and deliver this high of sound quality. I could tell immediately this amp had potential, and I wasn't wrong. I think out of the box, this amp sounds good but can be fatiguing after long sessions due to some of the harshness of the 6N2 preamp tube. Other than a 6AX7 there isn't much choices here, possibly the 6DJ8, but these don't impress me either. For some people who maybe shy about modding, this may not be a good amp to buy, you may not be happy with the sound out of the box. For the ones who aren't afraid to do a little soldering and swapping in better tubes, then you will be rewarded with a very decent sounding, inexpensive amp that will provide you hours and hours of enjoyment.
     

     

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  2. zincman

    zincman Active Member

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    Nice review Dan, well written. As an owner of chinese stuff along with US made, they are hard to beat on the value for sound dollar. Although my Dareds lack the top quality materials I just remind myself how much they cost. Thanks again for a nice review.
     
  3. DanTana

    DanTana Super Member

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    Thanks zincman, these amps sort of remind me of the value of the old Dynakits and Heathkits of the 50's and 60's. One thing I didn't mention in the review, was the fact this is an integrated amp, and allows for two inputs, and has a headphone output and volume control. The volume works with the headphones connected or not, so you can adjust the gain as you like. Two mods I am considering next, replace the coupling caps with something "known" like Auricaps, and bypassing the integrated functions to shorten the signal path like a dedicated amp.
     
  4. DanTana

    DanTana Super Member

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    Just an update on the latest incarnation, picked up four "Orange Drop" caps, film and foil type, put those in and added a resistor to the negative feedback loop to the input tube. The Orange Drops were only about $2.00 each and probably the best deal on capacitors anywhere. I replaced the "Ming-Da" caps and the Orange Drops were nearly twice the size, a bit of a hassle getting one in but the rest installed fine. The resistor I just matched the size of the existing one, and soldered it in series.

    As soon as I powered it on I knew it was different, it was so much clearer sounding and the highs were very clean. Even the bass seemed stronger, although maybe not lower, but more controlled might be the best term to use. Sometimes you never know what your missing until you change it, and I realized I wasn't hearing as much as the music as I should be. The midrange is now where during certain songs, I can make out the lyrics much better. I wasn't always sure if it was my source devices, my phono cartridge or CD player that sometimes seem lacking, not knowing it was my amp. Having changed it from Ultralinear operation to Triode, feedback isn't needed, or at least as much. Now I can tell that something designers use to reduce distortion, can reduce detail and clarity also.
     
  5. teapot97

    teapot97 New Member

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    I owned a mingda MC 34B. How can I rewire to 12v to accomodate 12ax7 tubes ? Any photos to follow ?

    Many thanks.
     
  6. DanTana

    DanTana Super Member

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    Last edited: May 8, 2005

     

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  7. Andyman

    Andyman Scroungus Stereophilus Subscriber

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    Dan:
    Nice reviews. Have you had a chance to audition that almarro A205A yet? I wonder how it compares to the Ming Da.
    Let us know!
     
  8. DanTana

    DanTana Super Member

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    So far that little Almarro has been a pleasant surprise. I wouldn't think a little SE EL84 amp could put out so much power and sound as nice as it does.
     
  9. Andyman

    Andyman Scroungus Stereophilus Subscriber

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    I sure love mine. One thing about the power though is that someone in the other link stated that a lot of the gain is loaded into the bottom of the volume pot. I've never had mine past 10:00 on the La Scalas, and things change fast from 9 to 10, so that wouldn't surprise me at all. It definitely has more volume at equivalent settings that the 22 wpc Harman Kardon 430 it replaced. It may run out of gas after 12:00, but unless I get a bigger house, I'll probably never find out!
     
  10. THOR

    THOR Fearless Prophet

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    Glad your enjoying Dan! Someday I'll have to get another and try the things you've done. That is if the Miata ever gets done ;)
     
  11. DanTana

    DanTana Super Member

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    Chris, So far, the Ming-Da has been one of the best audio purchases I have ever made. Thanks again...and get that Miata done now that the weather is improving.
     

     

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  12. craigcook

    craigcook New Member

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    just curious, who sells these? I saw an ebay listing by jim60815, not sure if it was legit ($528 + $145 shipping).
     
  13. DanTana

    DanTana Super Member

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  14. teapot97

    teapot97 New Member

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    Thanks for the diagram. Do I need to rewire all four preamp tubes 6n1 and 6n2 ? By the way, on the four preamp which is 6n1 and 6n2 ? ther is no label. After rewiring it, all four would be 12ax7 tube or 2 tube 12ax7 the other tube could 12at7 etc.
     
  15. teapot97

    teapot97 New Member

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    On the diagram to convert to 12ax7 on pin 9 need to attached the wire from pin 5 and jumper 4&5. Do I have to do on all 4 tube sockets ?
     
  16. trickytree

    trickytree New Member

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    30
    I have had my Ming Da MC34-B for about a month now and it is an amazing little amp. I have had this valve itch for some time but have never taken the plunge and tried one. This one came up secondhand so was even more of a bargain and I must say it is possibly the best amplifier that I have owned. In my system it does all that my previous Naim pre-power combination did and then some. Amazing.
    Apart from a set of Sovtek 5881's that are available as an option when buying the amp from Edenlake it is standard at the moment but I must admit that it is great that Dan has done so much work that we can all copy, cheer's mate!
    I must say I just luuuurve the look of those Mullardesqe EL34's so i'll get me a set of those and also have a go at modding for the 12AX7's but will not be in any great hurry, i'm enjoying it as it is thank you very much!
     

     

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  17. DanTana

    DanTana Super Member

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    Teapot, Sorry for the late reply, I've been out of town the last week. You do not HAVE to do all 4 sockets, but if you do then your correct with using say...12AU7's where the 6N1's were and 12AX7's where the 6N2's were. I've tried 12AU7's, 12AV7's, ECC99's and 5965's in that spot and to me, the ECC99's, sound best, but have less gain, the 12AV7, 5965 sound very good too, and have more gain. I've got RCA 5965's and GE triple mica 12AV7's that are pretty darn good sounding also. I've also put the 12AV7's in the preamp spot and they were pretty good there too. Of course the gain is far less, but they seem to not color the sound very much. Right now though I'm sort of mixed between the new GT Mullard copy 12AX7's and the new Svetlana silver plate 12AX7's. The Svetlana has some outstanding bass and nice highs, Mullards seem more neutral. At least with the mods, you can have many more choices with your tube swapping. One thing I wish I had done before wiring the driver sockets, is trying the 6H30pi Russian tube, someday I may change it back and give that tube a try.

    Trickytree, Glad your enjoying yours, it truly is one of the best bargains in tube audio out there.
     
  18. trickytree

    trickytree New Member

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    Dan,

    I'm wondering if you would be kind enough to talk me through how to set the bias on the Ming-Da? I bought mine secondhand and only got the following photo with it....no instructions. Although I have done a bit of DIY before I have never had a go at a valve amp.

    My amp is the same as pictured apart from the cathode resistors that are square ceramic 5w 10ohm.


    [​IMG]


    TIA,

    Paul.
     
  19. DanTana

    DanTana Super Member

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    That's a decent picture to go by. Use your DMM and place the negative on "B", then put the postive on either "A" or "C", then you'll adjust the pot "D" if your probes are on "A" and "B", you'll adjust pot "E" if your probes are on "B" and "C". At first move the pots very slightly so you can get which way increases and decreases the voltage. You didn't say which tubes you were using so I'd use 25mv for 6L6 and 30mv for EL34. Your probes will be on either side of the resistor when your adjusting the voltage, you'll have to go back and forth many times until it steadies. One side effects the other so it will take a good 10-15 minutes probably, maybe longer. First you may want to do a quick check on the voltage to see if any of the tubes are way out of spec, and do those first. Also, I'd give the amp a good 10-15 minutes at least to warm up, so if everything is good, just leave it on until then and recheck. Also, I use a 8 ohm 20 watt resistor across the speaker outputs. You can get those at Radio Shack, that will protect it in case of oscillation.
     
  20. trickytree

    trickytree New Member

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    Thanks very much Dan, much appreciated.


    Paul.
     

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