Super reverb 4 ohm speaker load.

[Helmholtz]

Confused.

An original BF '65 SR (AB763) has a 2 Ohm output and its internal speakers are wired for 2 Ohm.

[g1]

I have a 65 Super and run 4 Celestion GOLD at 8ohm total. Then a Open Back Cab with 2 Celestion Vintage 30 at a 4ohm load connect to ext speaker jack. Runs my Amp with the 2-12 at total of 4ohm load and it Screams Big Time.

If the internal speakers are wired for 8 ohm total, and you add a 4 ohm ext. cab, the total load becomes 2.67 ohms.

[Tbarshowdog]

I have a 65 Super and run 4 Celestion GOLD at 8ohm total. Then a Open Back Cab with 2 Celestion Vintage 30 at a 4ohm load connect to ext speaker jack. Runs my Amp with the 2-12 at total of 4ohm load and it Screams Big Time. Love the Gold and 2-12 Vintage 30 Fill bottom end and chime Top end from Gold 4-10. Does not hurt the Amp like that and sounds Amazing. Any one tried this like me ? Also tried the 2-12 Cab with G12M Greenbacks 8ohm Cab per 2-16ohm speakers wired to 8ihm load. and Also sounded amazing. Comments ?

[hasserl]

This thread is kind of dated now, but just for reference, you could replace the 6L6GC power tubes with JJ's 6V6S power tubes (with a rebias), which will match up impedance wise with the two 8 ohm speakers. It also will quiet the amp down a little making it more useable in most places. And you'll get a little more grind out of it as the 6V6's break up earlier than the 6L6's, if you like that sort of thing (I do!).

[Hella1hella]

Well, it looks like the fun is over for a bit! The amp has been giving me some shocks and one of the power tubes wont light up unless given a (very small) tap.... BUMMED! Just got new power tubes and grounded cable too... I am taking it in tomorrow and hopeing the tech gives me a discount since the amp was JUST in his shop a month or two ago to get everything I mentioned done.... He is known as the best tech in the area so I am hopeing its just something he overlooked and nothing too serious... Serious means $$ and $$ =new cabinet and speakers so I can A/B/Y this guy with my bassman!

[olddawg]

I will probably play at very loudest around 8. I just played live with a band with no mic at 5. Can you really just put some resistors inline with the speakers to create what ohms you want? I have heard of this before but like I mentioned earlier, I do not know too much about technical stuff. I can solder and what not and mod pedals quite a bit but nothing serious. What about what I said earlier combining a 8 and 4 ohm speakers resulting in like 2.67ohms?

Yeah you can do it. You have two 8 ohm speakers, right? Purist will say the resistors aren't an inductive load but you have speakers there also. Just wire it up like you would four 8 ohm speakers except substitute the 8 ohm 20 watt resistors for 2 of the speakers. I would parallel a resistor with each speaker and then parallel those 2. Personally, I wouldn't bother. I would just use the 4 ohm cab.

[Hella1hella]

I will probably play at very loudest around 8. I just played live with a band with no mic at 5. Can you really just put some resistors inline with the speakers to create what ohms you want? I have heard of this before but like I mentioned earlier, I do not know too much about technical stuff. I can solder and what not and mod pedals quite a bit but nothing serious. What about what I said earlier combining a 8 and 4 ohm speakers resulting in like 2.67ohms?

[olddawg]

How loud do you plan to crank it up? You can always parallel up a couple of ceramic 8 ohm 20 watt resistors (they're cheap) with the two 8 ohm speakers to better match the load. Might even be a good idea if you are trying to hit the sweet spot at a slightly lower volume. A lot of this is splitting hairs IMHO. Generally you can run a 4 ohm load on a 2 ohm tap just like you can run an 8 on a 4 or a 16 on an 8.

[Hella1hella]

Alright awesome. I actually do not have any speakers yet. I need to order them I just wanted to do some research prior. I DO have a weber signature 10 that I just used for messing around that is 8 ohm, and I am ordering a JD NEWELL 2x10 cab. Would it be okay if I ordered a higher end weber 4 ohm and used it with the 8 ohm creating a weird 2.67 ohm load? I dont see why not but I am no professional and am so scared to do anything because I do not want to mess this amp up haha. I will eventually buy another higher end weber 4 ohm to go with the other one I just dont have all that cash right now so saving $100 for a while until I can replenish my spending stash would help greatly. I really like the weber stuff, I have them in some of my other amps.

[g1]

I guess I do not quiet understand. Two 4 ohm or 4 8 ohm equal out to 2ohms. So what is the difference?

I think what pdf64 was getting at with the 3db reference was that 4 speakers will sound louder than 2 speakers even if the total impedance is the same (you are moving more air). So if you end up turning the amp up to compensate, then you are working it harder.
For myself, I would agree with MWJB, the OT shouldn't have a problem running into a 4 ohm load. But now there are 2 places you are losing loudness, one is due to the impedance mismatch (you won't get as much power into 4 ohms as 2 ohms), the second is that you are moving less air (2 speakers rather than 4).
You only paid $65 and the original cab. is no longer original. Try it with the 2 speakers you have.

[MWJB]

Run it with 2x8ohm 10" speakers if you have them. Fender' Blues Deluxe runs a primary Z a little under 8K, old tweed 6L6 Fenders were 6-7K. It's doubtful that you would notice any accellerated deterioration of power tubes...unless you always run the amp harder because it's pushing a smaller sound wave & may be harder to hear on stage.

[Hella1hella]

I guess I do not quiet understand. Two 4 ohm or 4 8 ohm equal out to 2ohms. So what is the difference? I mainly want 2x10 to save weight. I do not really want to change any original parts unless its caps or something that needs to be changed. Any good suggestion for 10" 4 ohm speakers if I go that route?

[pdf64]

'So even two 4 ohm would be worse than 4 8 ohm'
It depends how you are likely to use it / how hard you intend to drive it, so it's debatable, your choice really.
Personally, if you've already got 2 10" speakers you're happy with then I'd change the OT, as you may not like the Webers.
Whereas if you fancy trying out the Webers, then it makes sense to get the 4 ohm version.

[Hella1hella]

There is actually no speakers at all. Someone put it in head form before me but I only paid $65so I could not pass it up ha ha. So even two 4 ohm would be worse than 4 8 ohm?

[pdf64]

Regards replacing the OT, an alternative view is that much of the value of the amp will be in it having working original transformers. By fitting a replacement (and so keeping the original safe), you will be protecting it, enabling it to be refitted when you sell it.
Bear in mind that with only 2 speakers, you'll be down 3dB so are likely to crank the amp harder to compensate, thereby putting more stress on the 43 year old layer of varnish which is all that's insulating your OT windings.
It would be a shame if you got the speakers and then damaged the original OT.
I assume that the speakers aren't original?