AA864 Bassman

[labb]

Anyone built one? What issues if any. How does it compare to the 5F6A?

[Ed_Chambley]

Owned one and built a few. Does not compare to the tweed. Blackface in its purest form. Punch, clarity and needs to be pushed a bit harder to break-up.


What a lot do is build the left channel like JCM 800 and the middle channel the Bassman. Played one for a while and is one of the more popular studio amps in Nashville.

[labb]

Thanks Ed. I really have the bug to build it...Just got to justify it.

[sluckey]

I played bass through one for a couple years back in the '60s. It was a popular bass amp, especially for small country music juke joints. Bass player in my first rock band had one too. The bass channel is too muddy for guitar and the normal channel (same preamp as AB763) was too dark for guitar with the stock 2x12 bass cab, but actually sounded good with guitar voiced speakers.

Lot's of people modify these for a more Marshall sound. You're the first person I've heard say they want to build one.

Here's a pic of one back in the '60s. It's being used as Leo intended. 

     http://sluckeyamps.com/misc/Intruders.jpg

[purpletele]

I played bass through one for a couple years back in the '60s. It was a popular bass amp, especially for small country music juke joints. Bass player in my first rock band had one too. The bass channel is too muddy for guitar and the normal channel (same preamp as AB763) was too dark for guitar with the stock 2x12 bass cab, but actually sounded good with guitar voiced speakers.

Lot's of people modify these for a more Marshall sound. You're the first person I've heard say they want to build one.

Here's a pic of one back in the '60s. It's being used as Leo intended. 

     http://sluckeyamps.com/misc/Intruders.jpg

I like that photo, I have seen it before a few times.

[Ed_Chambley]

Check out Mike Scaggs youtube. He a member here. P2pamps. Send him a pm with your email and ask him for the Marshall mod Baseman. Also look at a couple of videos where he is building. Ask him for  the mod layout. It puts a master volume in channel one and is voiced for a JCM 800 or if you wish call It a 2204 preamp.


He has a video showing the sound. Or if you just want to dive in I know how  it is voiced and modded and have the schematic and layout on one of my computers. Ok will find it if you decide to build.


One of the greatest amps and if not an original you can add a loop for verb or whatever and have and your bassman will play pretty and the left when switched will get early grind. The 2204 Marshall preamp IMO produces the nicest preamp distortion without going overboard, but it too will play clean with the master open.


Ab switched and you truly have 2  good usable amps in one head. True, you need to consider the PI is a 12at7 and since you are building you can find all kinds of circuit mods, but as Sluckey said use an ab763 values and add the Marshall mod and you will be pleased if you like blackface tone and a tight feeling JCM 800.


With the tweed bassman you have a few things different. A 12ax7 PI tube and doesn't provide as much current. The first stage bypass cap is HUGE. It  does have presence.


Blackface It has more mods, which equate too getting dirty earlier. You can always  tweak a bassman. I have had them setup with adjustable nfb and an added gain stage which the tube is already there. Add a 250k mid pot for a raw and it gets even meaner.
I too have biased el34 in them. This is odd as it then really sounds like a 800, but the fender values work well too and the raw pot grinds more.