Marantz Model 8b Stereo Tube Amplifier Fully Restored

For your consideration, we have the venerable Marantz Model 8b Stereo Tube Amplifier. We picked this unit up from along with several Dynaco amps that an 88 year old gentleman had inherited from his father in law. It had been out of use for at least 30 years, and just sitting in his workshop. This Model 8 had no tubes when we received it. As you can see in the pictures, the paint and finish is quite distressed, and while there are no dents or dings on the unit, it does have two holes drilled into the top centerish rear of the unit, and the Marantz badge is missing from the front. We thoroughly cleaned the unit, but it still  has some serious patina, and is in my opinion one of the coolest pieces to come through our shop. Once we restored the amp, I used it in my home for two years. The finish on the unit, and the optional cage have a beautiful look to them. I am only selling it because I acquired a pair of Marantz Model 5 Mono blocks that we restored, and it makes no sense to keep both. If you are in search of a pristine looking Model 8B, this is not for you. If you are looking for a fully restored vintage one with some character, you might want to consider this one. See the many pictures in the listing for further details, including the shots of the inside, showing the impeccable wiring and layout by Marantz, and the clean work performed Ben from Novalux Stereophonic. The unit looks even better in person. 

Inside, the unit is in excellent condition, and now in perfect working order. It is easy to operate, and biasing is no problem using the switch on the front panel. 

The unit comes with a set of 4 Electro Harmonix EL34's, 2 Admiral 6GC7's, and 2 RCA 6BH6's. All tubes tested well on our Amplitrex AT1000 tube tester. 

As mentioned, after we restored the unit, I took it home for about two years and ran sparingly  in a modest system in my living room.

While we know that some collectors prefer to leave these units completely original, you must keep in mind that this amp was manufactured in the 1960's, so we prefer, in part for safety reasons, to go through and selectively restore them using modern components. All parts that were carefully removed, have been saved and will be included in the sale. They could be reinstalled if one would choose to do so.

While we service most of the units that we sell, we were fortunate to have the extremely talented Ben Hase of Novalux Stereophonic do the work on this highly collectable unit. Ben is very experienced, talented, and extremely intelligent. Anyone who is able to get a piece of gear that he has restored is very fortunate, as his work is impeccable. 

The following restoration work was performed on this amp:

• Power Supply Rebuilt
• Original caps disconnected but left in place
• Voltage doubler caps mounted in existing side clip
• Multi-section cap relocated to vertical terminal strip - original color code maintained.
• Drifted 6.8K 1W carbon comp replaced with period correct NOS Allen Bradley
• Diodes replaced with modern UF4007
• Bias Supply Rebuilt
• Silicon diode was already in place, either later production or Selenium was replaced
   at some point in the past.
• Replaced diode with UF4007
• Double axial capacitor replaced with (2) single axial caps
• Cleaned bias selector switch
• Signal Path Component Check
• Loaded in tubes for a base line test post PS rebuild
• R channel works, L channel clips early on one side and A2 would not bias.
• Found blown screen grid resistor on A2 socket

• Also found incorrect screen grid value on B1 Socket - 220 ohm instead of 100 ohm.
• A1 drifted to 130 ohm on a 10% tollerance parts
• All four screen resistors replaced with 5% Carbon Comp( new production Kamaya)
• Paper capacitors replaced, .22uF and .022uF w/ Polypropylene film
• 15uF axial electrolytics replaced.
• Final Testing and Alignment
• Retested after aging parts replaced, both channels now work.
• Set Bias and tested both channels to 40W at 1%THD
• Calibrated AC Balance at 35W output
• Distortion less than .05% at 10W - 1KHz into 8 Ohm Load
• Set up for long term stress and listening tests - PASS 

The amp will be carefully packed in a heavy duty box, and surrounded on all sides with several inches of polystyrene foam. Water activated, fiber reinforced tape will be used on all box seams.