I also have a Ming-Da MC34-B amp. Basically it's exactly the same internally as the MC34-A, albeit a couple features and the 6.3v heater setup for the preamp and input tubes. I wired my preamp tube to 12v and use 12ax7 tubes in that position. Simply remove the wire off pin 5, remove pin 9 from the gound, take the wire from pin 5 and route it to pin 9, and jump pins 4 and 5 together. I've also used 6DJ8 in the input tube spot, but wasn't as happy with the sound as the 6N1, i'm considering the 6h30 tube next in that spot. I've also replaced all the 6P3 tubes with the "new" Mullard reissued EL34's. After biasing them and the new preamp tubes, the sound is incredibly improved now. I would like to know if anybody has successfully replaced the 6N1 with the 6H30 yet. Otherwise, I'm going to wire it for 12v and try some other input tubes.
Dantanna, All,
I am using vintage Mullard EL34's in my Ming Da MC34B. Cathode current is set at 35 mA idle per valve with the grid bias pots. I have placed 6BK7B's in the long tailed phase splitter socket and use the supplied 6N2 input amp tubes as I have so far found nothing else that sounded as good stuffed in the sockets as wired.
The power output is now 28 watts RMS per channel, both channels driven instead of 18 watts with the originally supplied 6P3P's.
The amplifier sounds fantastic!!!!
What is all this about re-issued Mullard EL34's??? How can a long defunct company reissue something? If this is like RCA, or Altec then only the name is being obtained, being disparaged by no talent charletains working for the shareholders for profit in exchange for substandard modern c r a p which sells only because it is badged with a once famous and respectable name.
I am using vintage Mullard EL34's in my Ming Da MC34B. Cathode current is set at 35 mA idle per valve with the grid bias pots. I have placed 6BK7B's in the long tailed phase splitter socket and use the supplied 6N2 input amp tubes as I have so far found nothing else that sounded as good stuffed in the sockets as wired.
The power output is now 28 watts RMS per channel, both channels driven instead of 18 watts with the originally supplied 6P3P's.
The amplifier sounds fantastic!!!!
What is all this about re-issued Mullard EL34's??? How can a long defunct company reissue something? If this is like RCA, or Altec then only the name is being obtained, being disparaged by no talent charletains working for the shareholders for profit in exchange for substandard modern c r a p which sells only because it is badged with a once famous and respectable name.
Great to hear from other happy Ming-Da MC34-B owners!! I'm curious to hear more about your choice of driver tube, rcavictim. I have put the 6DJ8 in there and it wasn't bad, just not as good as the 6N1, try rewiring the preamp socket where the 6n2 was and put a JJ Tesla 12ax7 in it's spot.
As far as the "new" Mullards go, SED bought the rights to use their logo and trademarks. Supposebly, these reissues are copies of the yf-4 version of the EL-34's. I bought them for a couple reason, I had read they were good, the Mullard logo looked kewl, and if I didn't like them I'm sure I could sell them easier. So far, I'm really happy with them, I also strapped them into triode mode and "sweet" is probably the best way to describe them.
As far as the "new" Mullards go, SED bought the rights to use their logo and trademarks. Supposebly, these reissues are copies of the yf-4 version of the EL-34's. I bought them for a couple reason, I had read they were good, the Mullard logo looked kewl, and if I didn't like them I'm sure I could sell them easier. So far, I'm really happy with them, I also strapped them into triode mode and "sweet" is probably the best way to describe them.
DanTanna,
I played with various 6DJ8's and 6922's (in both holes) but was not impressed. I considered trying a 6CG7 (excellent driver tube) but haven't. I was totally surprised by the 'air' added by substituting the 6BK7B for the 6N1P.
Regarding the Mullards. "Is that a Mexican poncho or a Sears poncho?" You tell me it's a Sears poncho. Good luck with them. Where might someone find these and how much do they set one back? This question coming from someone who is not at all impressed yet with EH offerings based on experience with only the 6CA7 fat bottle.
I think the old Mullards I have are 2nd design circa early 60's. They have seen a lot of use and still with emission like new are fantastic reliable valves.
I should add that I also had purchased a MC34A amp when I bought three MingDa's for evaluation. I and others who heard a-b comparisons all agreed that as supplied, with Chinese valves, the cheaper MC34B sounded noticeably better. I kept the MC34B for my personal use (it is now driving the Ultor-X speakers in my Avatar creating a 3D soundstage that betters anything I'd heard before or since), and sold the MC34A. I sold a new MC34B to a customer in the US who was blown away by it's sound quality and power when compared to quality brand SS 100w/ch equipment.
I played with various 6DJ8's and 6922's (in both holes) but was not impressed. I considered trying a 6CG7 (excellent driver tube) but haven't. I was totally surprised by the 'air' added by substituting the 6BK7B for the 6N1P.
Regarding the Mullards. "Is that a Mexican poncho or a Sears poncho?" You tell me it's a Sears poncho. Good luck with them. Where might someone find these and how much do they set one back? This question coming from someone who is not at all impressed yet with EH offerings based on experience with only the 6CA7 fat bottle.
I think the old Mullards I have are 2nd design circa early 60's. They have seen a lot of use and still with emission like new are fantastic reliable valves.
I should add that I also had purchased a MC34A amp when I bought three MingDa's for evaluation. I and others who heard a-b comparisons all agreed that as supplied, with Chinese valves, the cheaper MC34B sounded noticeably better. I kept the MC34B for my personal use (it is now driving the Ultor-X speakers in my Avatar creating a 3D soundstage that betters anything I'd heard before or since), and sold the MC34A. I sold a new MC34B to a customer in the US who was blown away by it's sound quality and power when compared to quality brand SS 100w/ch equipment.
I bought the EL34's from Triode Electronics for $77.00 a matched quad. I have them in triode mode and they sound very good.
Another update on my project, I wired the driver socket, formerly the 6n1 to 12v heater, and put in an ECC99 and am very happy with that tube, I was disappointed with the 6DJ8 myself. I also tried some clear top RCA 12AU7's in that spot, not quite as dynamic as the ECC99's.
Another update on my project, I wired the driver socket, formerly the 6n1 to 12v heater, and put in an ECC99 and am very happy with that tube, I was disappointed with the 6DJ8 myself. I also tried some clear top RCA 12AU7's in that spot, not quite as dynamic as the ECC99's.
rcavictim, I bought all the tubes from Triode, the ECC99's are available there too, very reasonable and after about two weeks of running it that way, I'm pretty happy with them. Seems with the ECC99 in there, it has become more sensitive to the changes of the preamp tube. Meaning I can hear the differences more clearly now than I could before. I was thinking of trying an 12AT7 in the preamp socket. I'm using the JJ Tesla and EH's in the preamp socket, both sound good but in different ways. Next I was considering putting in some higher quality coupling caps, and trying instead of .33uf ones, some .22uf ones.
DanTana said:
DanTanna,
That amp makes great bass. Reducing the size of the coupling caps may screw that up. I have had no urge to go inside my amp at all except to adjust bias. As for changing already pretty good quality coupling caps (Solen) to some boutique jobs that could cost what the entire MingDa amp wholesales for in China, you would probably get more improvement for the dollar in room treatments or loudspeaker upgrades IMO. As far as tube rolling, I only tried about four different types and stuck to only those that required no changes of filament pin wiring at the sockets. Let us know how the 12AT7's sound in the preamp socket.
Using 6N1P etc.
I have a preamp which has a cathode follower output.
I have found that I can drop 6DJ8, 6N1P, 6922, 6ES8 into the socket and they all work nicely at very similar operating point.
So which do I prefer?
Depends on which power amp I'm driving - with most of my valve amps I like the 6DJ8 best.
With my good solid state power amp I definitely like the 6ES8 best. This is definitely a variable mu tube and you get a SET like characteristic that as you increase the volume (signal level) you get increasing asymetrical distortion (due to the variable mu) and the sound "warms up" or "wets" or whatever description you like to use with increased signal level (as 2nd Harmonic distortion is added). This despite it being in a cathode follower (ie 100% feedback).
For those MANY of you who say you don't like the sound of a cathode follower in your preamps - bung in a 6ES8 (ECC189) and have a listen.
Cheers,
Ian
I have a preamp which has a cathode follower output.
I have found that I can drop 6DJ8, 6N1P, 6922, 6ES8 into the socket and they all work nicely at very similar operating point.
So which do I prefer?
Depends on which power amp I'm driving - with most of my valve amps I like the 6DJ8 best.
With my good solid state power amp I definitely like the 6ES8 best. This is definitely a variable mu tube and you get a SET like characteristic that as you increase the volume (signal level) you get increasing asymetrical distortion (due to the variable mu) and the sound "warms up" or "wets" or whatever description you like to use with increased signal level (as 2nd Harmonic distortion is added). This despite it being in a cathode follower (ie 100% feedback).
For those MANY of you who say you don't like the sound of a cathode follower in your preamps - bung in a 6ES8 (ECC189) and have a listen.
Cheers,
Ian
Re: Using 6N1P etc.
Ian,
I have a whole whack of NIB old stock 6ES8's, so I did try them in the MingDa MC34B. It played, and the variable mu was readily apparent, but it did not sound good. It is interesting to leave stock tubes in the one channel while you make tube changes in the other. That would be a nice tube (in part because it is a triode) I think for a dynamic expander.
gingertube said:
Ian,
I have a whole whack of NIB old stock 6ES8's, so I did try them in the MingDa MC34B. It played, and the variable mu was readily apparent, but it did not sound good. It is interesting to leave stock tubes in the one channel while you make tube changes in the other. That would be a nice tube (in part because it is a triode) I think for a dynamic expander.
6BK7B's on ebay
Earlier in this thread I noted the magic I got from using 6BK7B's in the long tailed phase splitter of my MingDa MC34B amp. No socket rewiring is necessary, just drop these in. I just saw that five NIB GE's are being offered on ebay in case anyone is interested. This is not my auction and I make this post as a public service announcement. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=67816&item=5765575505&rd=1
Earlier in this thread I noted the magic I got from using 6BK7B's in the long tailed phase splitter of my MingDa MC34B amp. No socket rewiring is necessary, just drop these in. I just saw that five NIB GE's are being offered on ebay in case anyone is interested. This is not my auction and I make this post as a public service announcement. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=67816&item=5765575505&rd=1
RCAVictim,
Im not familiar with the MingDA MC34B. Is the spot you tried the 6ES8 a cathode follower or a common cathode stage?
The preamp in which I did like the 6ES8 was definitely cathode follower, 150V rail, running at 8mA. That is, operating well up into its linear mu region at low signal level but traversing into the variable mu part of the curve on larger positive signal swing (less current) all mitigated and made more subtle by the 100% feedback of a cathode follower.
However we all have different tastes - hence the question, to resolve if we are comparing apples with apples.
Thanks
Ian
Im not familiar with the MingDA MC34B. Is the spot you tried the 6ES8 a cathode follower or a common cathode stage?
The preamp in which I did like the 6ES8 was definitely cathode follower, 150V rail, running at 8mA. That is, operating well up into its linear mu region at low signal level but traversing into the variable mu part of the curve on larger positive signal swing (less current) all mitigated and made more subtle by the 100% feedback of a cathode follower.
However we all have different tastes - hence the question, to resolve if we are comparing apples with apples.
Thanks
Ian
I wish I had a chance to try those out before I wired my socket for 12v just to compare. I'm not sure how it would compare to the 6N1 or 6DJ8 I had in that position. I found the 6N1 better than the 6DJ8, but I now find the ECC99 better than both of those tubes. I suppose I could rewire it back to 6v but now I have a ton of more options than I did with it at 6v. When you get tired of playing with those 6v tubes, rewire it for 12v and stick an ECC99 in there.
DanTana said:
DanTana,
You keep talking about 12 volts. Since there ain't no 12 volts in this amp did you add an additional xfmer for a 12 volt filament supply or are you merely referring to rewiring the filament pins so that center tapped 12 volt filament tubes like 12AX7, etc. will work in there on the existing 6.3 VAC?
I have aan mc34b and am using 12ax7 as the input and 12at7 as the phase splitter, the 12at7 imo is better here than the 12 au7.
I noticed no difference at all between the cheap 12at7 and a mullard cv4024, so that was a total waste of cash
didn't like ecc99 myself.
I suppose that means my heaters are 12 volts?
I traced the circuit out.
Its an ultralinear design, grid biased.
Input stage is an anode follwer directly coupled to a cathode follower,
direct coupled to the cathode coupled phase splitter.
very nice design, lovely build, and great sound. these are superb amps.
I noticed no difference at all between the cheap 12at7 and a mullard cv4024, so that was a total waste of cash
didn't like ecc99 myself.
I suppose that means my heaters are 12 volts?
I traced the circuit out.
Its an ultralinear design, grid biased.
Input stage is an anode follwer directly coupled to a cathode follower,
direct coupled to the cathode coupled phase splitter.
very nice design, lovely build, and great sound. these are superb amps.
Nice to hear from other fellow MC34B owners. The hardest thing is to fight the stigma of it being a "cheap" Chinese made amp. The input and phase splitters circuits are just the classic Mullard circuit. Nothing new there either, I'm glad the Chinese probably realised it's hard to improve on old tried and true designs. Very simple and "elegant" and sounds fantastic.
I recently purchased a pair of the new Groove Tube Mullard 12AX7M tubes. These are suppose to be reversed engineered from the original Mullards, piece for piece. I can say so far these are my favorite 12AX7 tube. Just a hint of warmth compared to EH or JJ 12AX7's, but a very good sounding tube, not forward like the EH is, better bass than the JJ, better highs than either.
I would love to try some of those Russian teflon coupling caps in it, they will be a tight fit, but it can be done.
I recently purchased a pair of the new Groove Tube Mullard 12AX7M tubes. These are suppose to be reversed engineered from the original Mullards, piece for piece. I can say so far these are my favorite 12AX7 tube. Just a hint of warmth compared to EH or JJ 12AX7's, but a very good sounding tube, not forward like the EH is, better bass than the JJ, better highs than either.
I would love to try some of those Russian teflon coupling caps in it, they will be a tight fit, but it can be done.
Give you guys the latest in my escapades. Now using the ECC99 as phase splitter and a 12AV7 as input. I find the sound very neutral and uncolored with good detail. I'm considering ECC99's in both spots, but gain is an issue. Now, I've swapped the "Ming-Da" capacitors for "Orange Drops" a bit of a squeeze since these are about twice the size, but well worth it for only $2.00 each. Then I reduced the amount of negative feedback by adding a resistor in series with the current one. I simply put another 100K resistor in there. I would of probably never of believed those two things would make that much difference soundwise, but it did. Almost as drastic as tube rolling, but with much better overall results. The detail and clarity sounds much improved, I can now hear lyrics that before I was struggling to figure the words out. The highs and lows also are much better, more control probably and tighter sounding. Since I put the EL34's in triode mode I was very happy with the sound, but I hadn't realized until now what I was missing.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.