TKO 65 Modification Question

[Bean1871]

Hi, folks,

And apologies if this (my first) post has been covered in the past.

I am a new bass player, recently purchased my first bass amp (a nice TKO 65) off CL, and like its capabilities, but wonder if it could be modded to handle an extension speaker. I have been looking at the Peavey Combo (Mark III, 260C), which is all the output I would expect to need with 130 watts at 4 ohms, but the bulk of the Combo concerns me a bit.

Here is my question: If the TKO 65 is rated at 65 watts at 8 ohms, could I reasonably add a jack for an extension cab to produce reasonable and safe output increase at 4 ohms (the manual recommends against a 2 ohm load)? There is a nice old Peavey 2x15 cab available locally at much less than the price of the Combo, but the 2x15 would address the issue of occasional need for more volume.

Thanks much!

Bill

[J M Fahey]

What does the TKO65 manual exactly say?
Why mention ohms in an amp which is connected only to its internal speaker?
Not fitting an extension speaker jack usually means it can't handle it.

[Jazz P Bass]

The schematic specifies an 8 ohm load.
You have to understand that the whole amplifier is spec'd to one load.
There are numerous changes that would have to me made to "safely" handle a 4 ohm load.
That is twice the current requirement (more or less) of an an 8 ohm load.
If you really want the skinny, call Peavey, ask for Glen.
He is a straight shooter.
If the amplifier can handle a 4 ohm load or not, he will tell you.
And if asked, he may even tell you why.

[Bean1871]

What does the TKO65 manual exactly say?
Why mention ohms in an amp which is connected only to its internal speaker?
Not fitting an extension speaker jack usually means it can't handle it.

J,
This is what the manual states:
TKO 65 SPECIFICATIONS:
POWER AMPLIFIER SECTION:
RATED POWER & LOAD:
65 W RMS into 8 ohms with DDT compression
POWER @ CLIPPING (TYPICALLY)
(5% THDI, 1 KHz, 120 VAC Line)
40 W RMS into 16 ohms
70 W RMS into 8 ohms
50 W RMS into 4 ohms
2 ohms not recommended

I'll be the first to admit that I am no electrician. This didn't make sense to me.
Thanks,
Bill

[J M Fahey]

Well, they are honest, no doubt about that, just a piece of information which should not have made it to a user manual, since it's not only useless to the end user, but confusing.
This is something the designer might have told a fellow engineer, Sunday night over a couple beers, as idle talk.
Yea, I know, Engineer talk may be dull.
The original speaker is 8 ohms, the amp puts out a very respectable 70W RMS into it, excellent.
What he also says is that it will not burn with a 4 ohm load ... but for that to happen the short circuit protection pads it down to only 50W RMS, the opposite of what you want.
So ... leave it as is.
*There is* something you can do, though.
If you are itching for that 2x15" , try to get also some pawnshop/Salvation Army special power amp , use it to drive the 2x15" , feed it the TKO line out signal.
Low cost thunder.

[Bean1871]

Thanks, JM,

Suddenly, that Series III Combo for $150 is looking like the better option...

[J M Fahey]

Buy it ... and still keep the TKO.
Use whichever you want at home or any fixed location, travel with the small one ... unless you need the other ... or both