Dynaco ST 70

This is a completely restored Dynaco ST70. Please read the rest of the item description as it is quite complete. In the last 30 years I have rebuilt many of these. By my fairly accurate count this is #215.

THE AMPLIFIER IN GENERAL - I know the individual who originally built this amplifier from a kit. When I got it from him he told me that he had built it sometime in the 1960s and had taken it out of service and stored it in a closet for at least the past 30 years. The general condition confirmed that the amp had seen limited use.  

CHASSIS - The amp was completely disassembled down to the last nut and bolt. The chassis is the more rare 3 screw version and there is also a 3 screw cage. The chassis and bottom plate had 1 small corrosion area by the outside of the right OPT. It was not through the nickel plating and cleaned up very well. The bottom plate has some discoloration on the inside but no corrosion. It looks like the quad cap leaked and the liquid discolored the plating on the inside only. The rest of the chassis had only a few pin point areas of corrosion and usual scratches. New high quality rubber feet were installed. The nickel plating was machine buffed and cleaned up very well. T The cage is one of the heavier cages and is straight and without modifications. It has been left the original brown color with a good emblem attached. My personal assessment of the chassis and cage is that they are conservatively an 8 on a 1-10 but the pictures tell the story pretty well.
TRANSFORMERS - The transformers have all cloth leads. Leads are clean with good color and still quite pliable. The power transformer is the tall stack 060 that is not potted. It is clean inside and shows no signs of overheating. The output transformers are A470 cloth leads and they are pliable and have good color. The insides are clean and show no signs of overheating. All of the transformer bells were stripped and powder coated a satin, light texture black. The lam stacks were repainted. I like to powder coat where feasible as it is far more durable and looks much better than a cheap rattle can paint job.

CHASSIS REBUILD - All electronics under the chassis deck were rebuilt and only the choke and bias pots were reused. Installed are quality speaker binding posts, and a new circuit board. The deck tube sockets are NOS. The board sockets are ceramic. All wiring was done with 22ga. Teflon sheath, silver coated copper wire. The new circuit board is a heavy resin Vintage Electronics, original circuit, board. In my opinion they are the best available. All components were high quality and close matched. The coupling caps are original value Solens. I have a fondness for the Solens in the 70. They just sound right. The face plate is 1/8" aluminum that has been powder coated to match the transformers. It has been fitted with gold RCAs spaced at 3/4" c to c so you can use real world cables. The bias jacks have been moved to the rear of the amp. The amp was reassembled using NOS hardware. (Notice that all my screw slots are horizontal). The quad cap was replaced with a new Triode SDS under deck cap module. Much higher capacitance and 630 volt rated so you will not have the quad cap problems that plague many of these old Dynacos. This is a $150.00+ option installed. A disabled (dummy) cap was installed to maintain stock appearance.

TUBES - I am selling this amp with a quad of JJ EL34 tubes. All have been tested. 

The included rectifier is a new Sovtek 5AR4. 7199s are tested RCAs. An extra 5U4GB rectifier has been included. This is a good spare and also works well where house line currents are very high.

GENERAL STUFF- I have rebuilt dozens of these over the years. This amp is about as close to what David Hafler had in mind in the 1950s with modern day reliability and safety in mind. This amp has about 20 hours on the rebuild and it functions perfectly. It should last may trouble free years. I have represented it as best I can and I pride myself on being a reputable seller. I will guarantee this amp to be as stated when you receive it. I will guarantee my work for 90 days but I CANNOT guarantee 60 year old tubes or transformers. If you need to send the amp back to me for repairs at some point you will be responsible for shipping costs to me and any non covered parts. IF YOU BUY THIS AMP AND CHOOSE TO USE IT WITHOUT THE CAGE BE WARNED THAT THERE ARE LETHAL VOLTAGES ON THE BOARD AND UNDER THE DECK. ALSO THE TUBES ARE SEVERELY HOT.

SHIPPING and PAYMENT - I have shipped dozens of these over the years and pack for the worst. ABSOLUTELY no overseas sales. Tube gear has a tendency to not ship the best and shipping cost globally can be prohibitive. My domestic shipping cost is reasonable for the way I pack. Payment only through Pay Pal to a continental US address for your protection and mine. 
I am open to reasonable offers.