MODIFIED MING DA MC-2A3 TUBE PREMAPLIFIER - (sold)
I have too much equipment at the moment, and this piece is not getting much use since I have decided to go with SS preamps for all of my tube amps. I am, therefore, regrettably putting this preamp up for sale since I need the space in my audio rack and have other things I am looking to purchase.
For various reasons, I prefer not ship this preamp and would really favor a local deal (I am in Chadds Ford PA which is not too far from Philly and Wilmington DE). In fact, to complete a local deal, I am willing to meet someone within a reasonable distance and (if at the asking price) I will throw in some extra benefits (for example, a few extra tubes and/or waive Paypal fee).
The ideal situation would be for someone to hear the preamp before purchase, so a local demo is available and encouraged.
I will ship in the USA, but see the disclaimers in my “Terms and Conditions”.
I may be interested in some trade although my needs are few. More info is provided below.
This preamp in and of itself is a beast (weighs well over 50 lbs), and is very unusual in its design and construction. The preamp uses a pair of 2A3 tubes for voltage rectification, and an EL34/6SN7 combo for voltage regulation. In addition, the preamp utilizes two 6SN7 types and three 6922/6DJ8 types for gain. This is a line stage only – there is no higher gain phono stage. Notwithstanding, this preamp does provide a lot of gain.
While the stock version of this preamp is very good, there are some modifications published a while back (copies will be provided) that have been implemented to the power supply and internal circuitry that take the preamp to another level. Changes include the following:
added an RC filter to the power supply
added voltage balancing resistors across the power supply caps
output caps have been upgraded to Mundorf silver oil
upgraded caps for 6922 and 6SN7 sections
I did the upgrades myself (with guidance from the author of the article) and, while I am not too proficient in DIY work, the end result (while not professional grade in appearance) works nicely and operation is perfectly stable.
Photos of the unit after (second photo) and before (third photo) modification are shown.
Original cost (stock) for this preamp was about $1600-1700 dollars (taking into account the shipping cost if purchased directly from China). The upgraded parts were about an extra $250, not to mention all the time that was put into the upgrades. In addition, there is an upgraded EL34 (vintage Tesla E34L), and some upgraded 6SN7s (two Sylvania JAN-CHS-6SN7WGTA) and 6922/6DJ8 (2 Siemens ECC88 and one Philips (EI) PCC88) that come with the preamp.
I also have additional tubes I can make available for an upcharge.
The preamp comes with a full set of tubes (as indicated above), the original metal remote, the original tube cage (not pictured) and the original box and manual. I will also provide a computer-grade power cord (should the buyer desire that).
Physically and operationally the preamp is in excellent condition (at least an “8” on the Audiogon grading scale).
ONE OPERATIONAL NOTE – this is a Chinese-made preamp and the Chinese manufacturer used an input transformer that works at both 220V and 110V (switchable). While the preamp can work at 120V, tube life and reliability is greatly increased at 110V. This is a “hidden” issue for almost ALL Chinese equipment and not just this preamp.
AT THE ASKING PRICE, I will also include a small line conditioner that outputs at approx. 110V for a 120V feed.
Note – additional circuit modifications are possible (adding or changing resistors in a couple of places, for example, increase the resistors in the RC circuit mod) to more reliably use 120V without the line conditioner, but I have not implemented them.
I can provide additional pictures or info on request.
GENERAL TERMS AND CONDITIONS
Please note that this preamp is being sold ‘AS IS’, so a local demo is highly recommended.
As indicated above, I will ship in the USA, but understand that shipping will be expensive (two boxes will be necessary). In addition, although everything will be packed appropriately and securely, I am not willing to be responsible for any damage by a shipping company (but will assist in processing of any claim if needed). The preamp will be put in the original shipping box in perfect functional condition, so if it arrives with a functional (or physical) issue then that will be as a result of handling by the shipping company.
I can potentially take partial (or even full) trade value; however, my actual needs are very few. I might be interested in certain vacuum tubes (45, 46, 47, 7591/7591A, KT90, M8162/CV4024, Siemens or TF ECC801s, 12AY7/6072/6072A, a larger group of tubes, or other tubes at the right value), a pair of higher-efficiency speakers (like Tekton Lore), SACD discs, or possibly other equipment or cables at the right value. In any event, feel free to propose something, and I will respond to any serious proposal.
Cash is always welcome for a local transaction. Payment can also be via money order/cashier’s check/personal check preferred but, except for US Postal Money Orders, all must clear my bank first.
I also accept Paypal for convenience, but add 3% to use of Paypal. IF YOU PAY VIA PAYPAL, HOWEVER, A CONDITION OF YOUR PAYMENT IS THAT YOU EXPRESSLY WAIVE THE RIGHT TO FILE A PAYPAL CLAIM OR CHARGE BACK (but do retain the right to sue me in court should you so desire).
Please check my feedback on Audiogon, Videogon and Ebay (ID=baileyler) and buy with confidence.
