Amp head on top of cab?

[DEFIED]

Hey guys, I was just wondering if any of you have noticed a difference in recorded tones, if you have the amp head on top of the cab being recorded, than if the head was on a separate surface? Just something I was thinking about, maybe some of you have experience with this?

Thanks for your help!

 

[professorlamp]

....what?

 

[DEFIED]

Like if I have the amp head sitting on top of the cab rather than on the floor or a desk or something. Is there a difference in bass response or anything like that? Just a random thought, it might sound stupid, sorry hehe.

 

[professorlamp]

haha,Im practically 100% sure nothing would happen , you could move the cab around the room and it would sound slightly different listening IN THE ROOM, but a head is just y'know a head?
It's like if you move the tv remote the reception doesnt get better or worse does it

 

[PhilTheBeard]

the only thing i notice with that is less feedback but other then that it sound's no different to me either way.

 

[DEFIED]

Oh OK cool. I was just thinking more in terms of vibration absorption and stuff like that. But it sounds like it doesn't matter either way huh?

 

[slashvanyoung]

The difference is not sonically perceivable, at least for me.

 

[bryan_kilco]

I would imagine the only thing that would effect the sound would possibly be tube rattle from bass response which could probably make some sort of noise?

 

[Omega_Void]

The amp would in effect add mass to the cab, but how much this affects the bass response would depend on how rigid and heavy the cab is in the first place. Mesa cabs (for example) are pretty hefty to start with, less beefy cabs might show more of a difference.

It's like if you move the tv remote the reception doesnt get better or worse does it

No, but if I move the aerial around it does.

Since tubes are microphonic, amp sitting on the cab would transmit more vibrations and colour the tone more. Having the amp in a different room altogether would go the other way. Some individual tubes will be more microphonic than others, and the design and construction of the amp is a factor.

YMMV depending on your gear, but IME the audible effects are subtle at the most.

P.S.
Now I've mentioned aerials it reminds me that moving the amp away from the speaker will reduce the influence of any electromagnetic noise coupling from the amp to the speaker coils, and reduce HF coupling due to stray capacitance also. These are electromagnetic compatibility issues, which should be negligible if your amp was carefully designed with respect to EMC. Which isn't a given.

 

[SimonTaddio_Qc]

The quick answer starts with "No, but..."
And the long answer starts with "Yes, if"

Trust me, one way or the other won't fuck up your mix, and no one here could heat the difference between the two

 

[bartgabriel]

For me no difference. But sometimes it's indeed easier when you have the amp/head in your control room, and the cabinet is roaring in the 2nd room...

 

[bryan_kilco]

For me no difference. But sometimes it's indeed easier when you have the amp/head in your control room, and the cabinet is roaring in the 2nd room...

but, wouldnt that extreme length of speaker cable cause dB drop or introduce noise?

 

[grywolf627]

but, wouldnt that extreme length of speaker cable cause dB drop or introduce noise?

No. There is a reason speaker cables are not shielded. The signal going through them will not be amplified (and thus any induced noise will not be amplified) because the signal going through them is already amplified.

 

[bryan_kilco]

No. There is a reason speaker cables are not shielded. The signal going through them will not be amplified (and thus any induced noise will not be amplified) because the signal going through them is already amplified.

hmm, did not know this. I just assumed the same applied as instrument cables.

 

[Pot]

The amp would in effect add mass to the cab, but how much this affects the bass response would depend on how rigid and heavy the cab is in the first place. Mesa cabs (for example) are pretty hefty to start with, less beefy cabs might show more of a difference.



No, but if I move the aerial around it does.

Since tubes are microphonic, amp sitting on the cab would transmit more vibrations and colour the tone more. Having the amp in a different room altogether would go the other way. Some individual tubes will be more microphonic than others, and the design and construction of the amp is a factor.

YMMV depending on your gear, but IME the audible effects are subtle at the most.

P.S.
Now I've mentioned aerials it reminds me that moving the amp away from the speaker will reduce the influence of any electromagnetic noise coupling from the amp to the speaker coils, and reduce HF coupling due to stray capacitance also. These are electromagnetic compatibility issues, which should be negligible if your amp was carefully designed with respect to EMC. Which isn't a given.

geek

 

[Omega_Void]

No. There is a reason speaker cables are not shielded. The signal going through them will not be amplified (and thus any induced noise will not be amplified) because the signal going through them is already amplified.

It's not so much that the sig isn't amplified, it's that the noise develops across the circuit impedance.

At the input of a guitar amp that's a little less than the impedance of the upstream output -- say 8-12 thousand ohms for a passive pup.

At the speaker, expect somewhat under 3 ohms for an 8-ohm speaker rising at higher frequencies as the voice coil's inductance becomes more significant than DCR, and falling again as the distributed capacitance across the winding starts shunting high frequencies to ground. So it's a lot less sensitive.

Also, with a 50-watt amp peaking at 28.28 volts and 2.5 Amps into 8 ohms, the SNR is better than the couple of volts you'd get from the guitar.

Another reason is that capacitance between the cable and shield will form a resonant circuit with the equivalent inductance of the amplifier's output caused by gain bandwidth. This can induce high-frequency oscillation when excited by an impulse, resulting in excessive heat dissipation in the output devices, as well as amplifying inductive kickback from the speaker coils which can cause damage by dragging the positive supply to higher-than-intended voltages.

geek

Kill me.