BassmanPaul

When a piece of my equipment reaches the end of its time with me I tend to pass it on to a younger player who could use it to great effect Recently sent one of my nephews , George, who plays bass, one of my six stringed instruments. I also sent him a Carvin BX1500 which will work on the 240V supplies you have over there. When one of my brothers visit next month he'll take all the stuff I had on my pedal board for George.

That's a nice old Precision you have there. Looks less battered than mine! LOL

Thank you for taking the time and effort to do this review though I'm sure you only did it to please your cat!!

Stewart is correct in his assessment of the Effects Loop being problematic. Linking the Send and Return has saved many different amplifiers from a premature death. I thank him for the information he provided.

I would just like to wish the OP in his new venture. Playing in front of a crowd is different than rehearsal time. I was part of a musical family so my dad had me singing on stage at the tender age of five! It was at a musical contest and I won! LOL

Both full compass and reverb are listing spare parts. Perchance maybe they have what you need. This is the link I found: https://www.fullcompass.com/searchresults.php?search_simple=true&txtAll=hartke+slider+pots

As did I. When I decided it wasn't for me I shipped it at my cost to a young guy on the infamous Talk Bass. I can't remember if he ever thanked me for it but hey that's in the past. The mods kicked me off the site for trying to warn them what a certain POTUS was trying to do. That's water under the bridge too! LOL

IMO those little boxes are not safe to use with a high power amplifier. The 1/4" phone sockets are simply not up to the current/voltage needed. They were originally designed for telephone switchboards operating at 48V DC and a couple of hundred milliamps. That's far below what a typical bass amp puts out. if they had used SpeakOns I would have no objections.

I'm don't think that an amplifier can be modified to run a load it wasn't designed for. It would entail a rebuild of the power amp AND the power supply. It would be costly even if it could be done. If you are considering this to enable you to run your existing cabinetry it would be far better get rid of the 4Ω box and get an identical second 8Ω cab.

My favourite amplifier is my Ampeg B15NF. The reason is obvious and it's staying in the fold. Second is the Class D 2KW stereo power amp that I built a simple tube pre-amp to drive. it feeds a pair of Acme B2 2x10 three way cabinets stacked on their ends for a vertical 4x10. When I feel crazy enough it will safely push all four of my Acme cabinets. If I gig this is the unit that goes along. Third was my Epiphone Constellation around 1968. which I loved made the mistake of trading it in, at Dawson's Runcorn store, for a Blonde Blackface Fender Bassman with its 2x12 cabinet. That amp was such a disappointment that I retuned it the next day. They had sold the Constellation so I just left the Fender there anyway.

Another thought is to get a replacement 240V power transformer from Fliptops in the US. It will somewhat devalue the amp but if you're keeping it it's better than messing about with external step down transformers. https://www.fliptops.net/catalog/p-100561/power-transformer-pt108-for-ampeg-b15nb12n

WOW! Talk about resurrecting a Zombie thread! LOL

I agree that there is something special about a B15. I just love the tone of my B15NF which I use as my practice amp. It makes practice time a pleasure. Mine is in better condition than the one in the link that Bill posted. In your place I would keep the 15" unit as you never know when the urge to play will grab you again. I do hope that the external transformer that you use is rated high enough to operate the amp safely.

If an amplifier has been correctly designed to operate, as all the ones I own are, into a 2Ω load they will run just as well at 2Ω as they will at 8Ω.

It's very unlikely to be class A! Too inefficient for a bass amp.

My comment was better said than unsaid! Many folks have done this and their amp has failed.

I remember that from my JBL days. I still love the brand though I don't use them to play through any more.

Don't connect both amps to the cabinet at the same time. Magic smoke comes out wen you do that!

Indeed that's what I do. After a while it becomes automatic!

Calculating parallel impedances is so simple as just about every one in the world has a calculator built into their phone. Formula is R1 times R2 divided by R1 plus R2. Using 8Ω and 4Ω: 4Ω times 8Ω=32, 8Ω plus 4Ω = 12. 32 divided by 12 = 2.67Ω. QED

Back in the late Seventies I used an H&H scoop twin 15. That was supplanted by a 'stereo' system with a 15" JBL K145 and two TL style cabinets housing JBL K120 12" drivers on each side of the stage. The amp was a SS 200W per side amp that I had designed for the purpose. The pre-amp was my build too. The whole shebang weighed a ton but sounded wonderful. The best part was the amplifier worked first time I powered it on. YEAH! I still own the power amp and it still works. Today I use a 2000W capable Class D power amp pushed by a simple tube pre-amp I again designed for the job. That drives either two or four Acme B2 2x10 three way boxes and I've never been happier.

Looks to me that the amp chassis has ventilated spacers on each side of the amp. Have you taken the amp out of the combo and taken a look?

@Thor please don't forget to keep us up to date with how you find the amp.

Swine!! I would really like one of those.

The cabinets are best if they are identical. If they are of different manufacturers do the battery test and ensure they are both working with the same polarity.