12" plus 15" speaker

[Gerry Brown]

Is there any harm in connecting my ToneBlock 202 to a 12" TT speaker and a 15" TT speaker at the same time as long as I'm consistent with the ohm ratings.?
Thanks,
Gerry

[George Biner]

The diameter of the speaker shouldn't matter, just the ohms rating. 2 8 ohm speakers in parallel = 4 ohms.

[Gerry Brown]

Thanks George. I don't really speak electronics. But here's my situation. I have an 8 ohm out and a 4 ohm out on the back of the Tone Block. I have an 8 ohm speaker (the 12") and a 4 ohm speaker (the 15"). My concern has to do with running two speakers with different resistance ratings simultaneously. I actually went ahead and tried it out and it sounds pretty darn cool. But my lack of electronic proficiency made me want to ask, in case there were long term implications.

[George Biner]

From the tone block amp manual:
"SPEAKER OUTPUTS: 8 and 4 ohm
jacks support optimum matching of
single or dual 8-ohm speakers, *or*
single 4 ohm cabs. 16 ohm loads may
be used in the 8-ohm jack by setting
the Master control at about 50% of the desired peak power (see MASTER, Pro Tip above). The amp is protected against no-load and abnormal loads;"

This seems to imply that you can't run loads on both outputs (see my asterisks above) -- but, since you've been doing it and it works, and the amp has protection, you will probably be OK. I personally would call Quilter and ask since it is not 100% clear from the way the manual is written.

So this is not an ohms question but an amp connection question.

https://www.lightweightguitaramp.com/cu ... manual.pdf

[Jeff Highland]

I would not do it.
The combination of an 8 Ohm and a 4 Ohm speaker in parallel is 2.67 Ohm and this is too low for the min 4 Ohm rating of the amp.
You will and obviously have got away with it at low volumes, but if you push it harder it may either cause damage or trigger protection

[Gerry Brown]

Thanks Jeff. I called Quilter labs and the guy I spoke with seemed to think there would be no problem. However, I'm inclined to err on the side of caution and use one speaker at a time.

[Bill A. Moore]

Their manual says 2 8 ohm is OK, or 1 8 or 4 ohm.
I suspect they used a switching jack in the 4 ohm that switches to the 4 ohm tap when something is plugged in. I generally do that with my builds if I can get a 4 and 8 ohm PT.

[Greg Forsyth]

I bought the Quilter Overdrive 202 and had the same question using an 8 ohm and 4 ohm together so I wrote Quilter Labs. Here is Pat Quilter's response:



"The power output is optimized for 4 and 8 ohms but the amp’s impedance is “forgiving” and your 2.6 ohm load will play OK. The amp will set itself for 4 ohms when you use both jacks. It won’t matter which speaker plugs into which jack when using both, but if you use only the 4 ohm speaker it should go in the upper, 4-ohm jack, and likewise, a solo 8-ohm speaker should use the 8-ohm jack."

I think the Toneblock 202 would function the same but not sure.

[John Ducsai]

I would keep the speaker's impedance matched as close as possible, otherwise one speaker will see more power than the other. Impedance also varies with frequency.
The output transformer of the amplifier sees the total load of the combined speakers, but the individual speaker impedance determines how much power goes to each.
See: https://www.gcaudio.com/tips-tricks/the ... mplifiers/

John D

[George Biner]

So the info Greg Forsyth got from Pat Quilter is the answer and should definitely be in the manual. I would also avoid 4 ohm cabinets.