HD 65 bass head ser#

59jazz

Hello,
Just found an HD 65 bass head locally in filthy shape, and am wondering about the date of manufacture. Serial # is AN00205.
I'm planning on sending out the chassis to a notable amp tech, for a thorough check up. I'll need to clean the head and speaker cab. No tears in the vinyl, but the protective corners are rusted and will need to be replaced. Thanks in advance!

59jazz Thu, 04/21/2022 - 21:04

Head and cab, smells bad! lots of cleaning for this one....came with a a dead mouse in the head cab; bonus!

Images

59jazz Sat, 04/23/2022 - 17:37

Tested the cab today, works great! Started cleaning the cab and I found this, a stamped plate with a ser# on it.

Images

Red66stingray Thu, 09/10/2026 - 09:03

Hello, I am new to this site and just wanted to tell you about my purchase of what I think is an early 1974 Music Man Sixty Five bass amp. I found it in an abandoned 1870 Church I was helping a friend clean out. When I saw it I asked my friend how to get in touch with the owner he replied back and sold it to me. The 78 year old man purchased the amp new and never serviced or replaced anything on it. He just used it for bass and keyboards in the early 70s. It has serial number AN00129 and has the original Amperex tube and two GE/Mullard tubes dated 1972. These were the imported tubes from Gt Britain and rebranded GE. No filter or caps ever touched. The choke is early 74 and the other transformers are late 73 which the output transformer that has been confirmed never replaced does have a 3-65 above the EIA606-733. My amp tech says the transformer is original to the amp and he said it reads 7 as the decade and 33 as the week because evey other date in the amp is 72, 73, 74 and absolutely no soldering or spliced wiring.He said the transformer company did this kind of dating on older transformers in the 60s and early 70s.  I would post photos but have not been able to make them go through yet. My amp tech  confirmed to the best of his knowledge it has not been touched as the original owner said also. The cabinet is a 115rh with an 1974 dated electrovoice sro15l in it. The original owner said he bought it new like this. The serial number on it is s00210. With all this said I will post photos and maybe it will help someone with dating or originality. I do plan on selling or trading this amp because I can't make myself service it to use it. It serves me no purpose to look at and I am into high gain amps mainly for what I do.

Red66stingray Mon, 09/14/2026 - 21:24

The front view is the day and place I found it and the other two is when my tech was checking it out. If I do not sell or trade it I will probably service only what it absolutely needs and keep it. Thought I would show the cabinet without the grill. I have lots more photos

Images
Profile picture for user mm210

mm210 Tue, 09/15/2026 - 08:28

The only thing it SHOULD have is the electrolytics changed, and that includes the one on the driver board. After that, it should last a long time. I suggest biasing it on the cool side, around 22mA PER TUBE, not that crap about .5 volts at point y. .5 volts works out to 25ma IF the tubes were equal, which they never are. The hottest tube should pull no more than 22mA to give the best tube life. Even a little cooler wouldn't hurt. 

Red66stingray Tue, 09/15/2026 - 12:36

Thanks for the info. I do not want to do more than necessary but I do want it to sound right.  I will probably replace the oem electricord and remove the death cap. It is the two blade cord with a place for the ground but never came from factory with one. It was not cut off or pulled out. 

Images

Red66stingray Wed, 09/16/2026 - 13:21

I agree with you but the man told me he bought it like this. Maybe the place he bought it from removed it but there is no sign it had one other than as you said the ground/earth wire. I ran the photo through google ai and it said that back in the early 70s electricord used the same injection molds for both 2 prong and 3 prong to cut down on production and tooling costs and that's why some have the ground hole with no prong and no signs of being cut. How accurate this is I can't say. I do know this was about the time requirements for grounded plugs came about and a lot of people would just cut them off. Both blades are identical sizes like two pronged cords. Most grounded plug blades have one larger than the other. This is one reason I wanted to get on this site to get more information from others that know a lot more than me. In the end its going to be removed anyway but I do like to know the history.

Unsubscribe from this forum topic