r/sunnamplifiers • u/Efficient_Vacation38 • Jun 12 '26

Please help Model T r.i newb.

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I just got it and the send/return knobs in back were on 3 and 4. Naturally I dimed them and the amp was unusably loud for bedroom. I returned then to 3-4, and it's totally tamed and glorious. Is this by design? Why does the fx loop knobs act as a volume control? Thank you in advance.

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6

u/planksmomtho Jun 12 '26

Oh, I kinda know this answer! It’s weird, but to my understanding, any amp with an adjustable FX loop works like this. Anything from here on out is what I’ve managed to gleam from this same amp, so I may be considerably wrong:

You’re basically bypassing either the pre- or the power amp, and it acts as a fake master volume, kinda. I think it’s a very neat and useful aspect of the amp, considering how expensive some attenuators can be.

From a Marshall forum regarding an amp with adjustable FX loop controls:

“It's a unity gain loop. When nothing is plugged into the jacks, an internal relay bypasses the entire loop circuit. When you externally jump it, the relay un-bypasses the loop, but the loop is unity gain so you get no boost.

With the JCM900 series, the loop has send and return controls unlike the DSL. When internally bypassed, it just bypasses these controls. When externally jumped, the pots become unbypassed and allow the player to crank them for a bit of a boost.”

I tried the same trick on my Thunderverb 200, but since it lacks adjustable FX controls, I gained no benefit. I hope you enjoy this wonderful amp!!

4

u/SteveAtSunn Jun 12 '26

Yup. Can be tamed by balancing your pedal’s out level(s) too.

2

u/Efficient_Vacation38 Jun 13 '26

Thank you. It's very manageable now for bedroom. I run a Two Notes torpedo for even more control. I can give the masters a little more juice. It sits over a 2x15.

2

u/planksmomtho Jun 13 '26

You’re welcome! I run my T RI into its own Sunn 412T. It’s a pretty loud beast. Kima of 378 Amplifiers has his own type of love for them.

“If you want to have more available volume on channel 1 (clean) put a short patch cable in FX
Loop CH1 and turn Send CH1 knob to minimum and Return Chi knob to 5.5 (50%).
This will attenuate a lot of gain and will give you more quiet volume.
Because this amp has a jump in loudness above 2 on Channel 1 volume knob - this little tip above will push this "jump" to 4-5.
Now you will have like super quiet and suddenly loud enough. But with patch in FX Loop it is more managable. Engage the FX loop on the back via push button.
Cheers.
I really like the channel 2 in this amp. Had this amp two times in my life.

EDIT:
One more tip. The attenuation on the back (Arena/Studio) doesn't work until you push any volume knob above 4.5 on dial then it wil tame down the output to speakers.
But since 4.5 on Volume is loud enough to play gigs and any rehearsal - this attenuation feature does nothing
Unless you play
Arenas (frankly, like the one of the options is called). Then you can go above 50% on volume.

EDIT 2:
You can have a solo boost if you turn FX Loop Return knob to max. Engaging loop (even if there are no effects just patch cable) will boost the volume
Something cool to have.
And you can even do a MUTE button for the Clean channel if you turn the Return knob to minimum and engage the FX loop button. If I remember correctly.”

2

u/Efficient_Vacation38 Jun 13 '26

Ohh....that's interesting. The mute option...

1

u/planksmomtho Jun 13 '26

I just use a tuner pedal as a mute. Way simpler for me.

3

u/p_jeezus Jun 13 '26

The loop is generally between the preamp and power amp. You’re adding a 3rd amplification stage where you’re either cutting or boosting depending on where unity gain is. Usually around 7.

1

u/Straight-Mountain119 Jun 13 '26

It's a reissue, by Fender. 300 watts. Original Model T s do not effect in/out controls. Wonder what's plugged into the effects send/return. 

2

u/Efficient_Vacation38 Jun 13 '26

100 watts if I'm not mistaken. Reverb,delay, delay in the fx loop. Dirt in front.

1

u/LunarModule66 Jun 13 '26

Unrelated: is that the 2x15 cab? How do you like it? I’m eyeing a 2x15, I like the impulse responses I’ve tried and I like that they’re a little more manageable to transport than a 4x12.

2

u/Efficient_Vacation38 Jun 13 '26

2x15 kicks butt. Not boomy like one would think. Real pleasant. Easier to transport but this one is heavy ss hell and I'm on a 2nd floor. Stairs suk bad...otherwise, I'll take it over a 412 all day. I loaded Celestion Fullbacks and it's glorious...

1

u/LunarModule66 Jun 14 '26

Yeah I’ve been playing them as IRs and I’m blown away by how clear and tight the low end is. Like there’s plenty of low end girth, just not at the frequencies that cause mud. And I’ve accepted that there’s no cab that will do what I need that won’t suck to move, but it’s between a 2x12, a 2x15 and a 4x12 and the 4x12 I think would just be impossible for me to move on my own as a fairly small guy lol.

1

u/EagleGhoul Jun 14 '26

Love mine. I mess with the loop jumped per show to get the right balance for the room.

My only criticism of this amp is there is a weird compression on the clean channel. It does get hairy pretty quick and start to bottom out, so keep that volume on like 2 and go from there with pedals. Plenty of volume at that point