It's no secret I like Ampegs - at least older ones. Newer ones I have had a hit or miss relationship with (hated the B-15R, loved the SVP-CL, like the Diamond Blue series even though it was solid state). Going back to elementary school I've played through mainly Ampegs or Polytones.
My first brush with Ampeg tube amps was in the 80s. I played through both a B-15S (70s vintage) and a B-25B with the matching 2x15" cabinet in high school. I now actually own that 2x15" cab I used back then and found a matching head. So I was used to "that" sound - they're virtually identical in tems of tube configuration.
In college, I picked up an SB-12 that I used for quite a few years until I found my '63 B-15N which has basically been my studio and jazz amp for at least 15 years it seems. These days I somewhat regret selling the SB-12, but I really don't need it. I've lusted after a B-15S for years, but could never pull the trigger. Once I found out about the B-18, I wanted one. Basically the B-15S/B-25B with an 18" (and 8ohms - not the odd 16ohm B-25B).
Years ago, I saw a B-18 in poor cosmetic condition (the tolex was all gone) at Cambridge Music in Boston (the store they had near Berklee for awhile), but didn't get it. At the time I thought it was too much money.
As luck would have it, one popped up in excellent condition on Craigslist about a month ago (not in my city) for a great price. I e-mailed the guy, and I just got it yesterday. Woo hoo! The B-18 seems to be all original except for one modification: a three prong plug, which is perfectly fine by me. I had that same mod done to my B-15 probably 10 years ago. The B-18 has the original speaker output cord and jack. My B-15 was modded years ago for them both to be 1/4". I may leave the B-18 unmodded as it works.
You also don't realize how much bigger and heavier the B-18 is compared to the B-15 until they are alongside one another (see the pic). The construction is also a bit different as well. The B-15 has small indents on the side under where the head sits, whereas the B-18 has metal handles and no indents.
I'm going to have my amp guy give the B-18 a once over since I noticed the output level seemed lower than my B-15. It could be a tube issue, but other than that, it plays and sounds great. It's definitely got a different voice than the B-15N. You can tell they are related (after all, it's got that Ampeg "sound"), but not surpringly it's got more bottom end. I really like what it brings to the table. Is it better? No, just different.
I'm going in the studio this weekend. Need to decide which amp to bring
