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Hd500 Effects Pre Vs Post Amp (w/ No Amp Assigned)

hd 500 hd 500 as effects effects pre post amp block

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#1 berkleegrad

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Posted 05 April 2014 - 11:04 AM

 Greetings all,

 

apologies, since I'm sure this topic has been covered before (maybe years back in the old forums)...

 

I use my HD 500 both as stand alone unit for FOH and/or as a straight up effects in front of an old Bassman rig....

 

When mashing up some new patches for use with my AMP I noticed that the sound of a my tube drive before the an empty amp block sounds completely different

Attached File  preamp.JPG   29.1KB   9 downloads 

 

than post empty amp block.

Attached File  postamp.JPG   26.81KB   0 downloads

 

I would expect this behavoir when there is an actual Amp assigned - I don't know why it surprised me that it is occuring when there is no amp in the amp block. I guess I was expecting just a transparent passing of the sound.  =:o

 

thanks in advance for your input, -Rick

 

 

 


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appreciate your indulgence, -Rick

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#2 radatats

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Posted 05 April 2014 - 01:18 PM

how do you have your inputs set?  are you using input 2 as Same or something different from input 1?  that will change the signal strength hitting the TD before the amp vs after the amp...


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#3 berkleegrad

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Posted 05 April 2014 - 07:36 PM

how do you have your inputs set?  are you using input 2 as Same or something different from input 1?  that will change the signal strength hitting the TD before the amp vs after the amp...


Radatats, thanks for taking the time to reply.

Input 2 is set to Variax which I'm NOT using. In the mixer, both input faders are centered and at 0dB.

The Tube Drive before the empty amp blocks sounds crisp and defined tonally; but when I place it (without changing any of the device parameters) behind the empty amp block, the Tube Drive sounds dull and lifeless. Been using the HD 500 for 3+ years - in a variety of ways and this is the first time I've every tried any effects behind an empty effects block. And, never noticed (or paid attention) any difference behind an assigned amp block. :-)

Again, thanks for your reply, -Rick
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appreciate your indulgence, -Rick

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http://www.facebook.com/rickrichbourg

http://groovetherapy.us/

 

 


#4 hurghanico

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Posted 06 April 2014 - 03:42 PM

Input 2 is set to Variax which I'm NOT using. In the mixer, both input faders are centered and at 0dB.

The Tube Drive before the empty amp blocks sounds crisp and defined tonally; but when I place it (without changing any of the device parameters) behind the empty amp block, the Tube Drive sounds dull and lifeless...

 

given that there isn't any amp (neither a deactivated one) in its empty slot, the position of that slot doesn't have any influence on the signal..

 

what really matters in your pictures is that in the first one your overdrive is in pre split position, and in the second picture the overdrive is instead in path A (separate path since there isn't anything shared in pre position)..

 

as you said, you are using 1 active input (being input 2 unusued)..

 

I and other people in this forum have demonstrated that when using a single input the same effect in pre-split position receives a signal lower than what it would receive in a separate path A, and the ratio is 1:2, ie, the same effect in path A receives a signal of double intensity, and consequently generates a different response..

 

there are 2 different theories on the POD routings which circulate in this forum: mine and that of the member "perapera" ..

 

the only thing in common between them is that we both agree that in a case like yours with 1 active input the response of the FX/amp changes depending on its position: in pre split or in path A (separate)..

 

my theory is here: http://line6.com/sup...e-of-the-hd500/

and for a bit more in depth post: http://line6.com/sup...ge-3#entry44388

if you want read also the "perapera" different theory, you should find it easily in this forum..

 

---------------

 

so very briefly I'm going to explain the signal routing behaviour of your case following my theory:

 

- in the first picture the overdrive is reached by your single active guitar input signal, and it sounds crisp and defined as you say..

 

- in the second picture the same overdrive is reached by the same signal of the previous example plus a copy of the same signal, giving a total of 2 signals together going into the same block, and you get a dull and lifeless sound as you say..

 

- why that POD's strange behaviour?

because there is a sort of fixed compensatory mechanism that comes into play in case you need 2 amps or more generally when you split your chain in 2 parts..

 

in these cases very commonly happens that at some point of a single chain you create a split point by enabling 2 full stereo paths A and B (simply by putting something into one of them) starting from there..

 

each effect/amp block generates 2 halves L and R of its processed signal, and the last block before the split point send its L part to path A, and its R part to path B, but being L and R two mono halves they need to be doubled to have again a full level in each path, and for this reason everything going into a full stereo path gets doubled from the point where starts the split point..

 

this behaviour is fixed and applies also if the split point starts at the very beginning of the chain, ie when the two paths are completely separate without sharing anything..


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#5 jandrio

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Posted 07 April 2014 - 02:06 AM

1st picture: tube drive applied over BOTH paths

2nd picture: tube drive applied ONLY over path A, path B carries pure guitar signal.

 

c attached abstract from "POD HD500 Advanced Guide v2.10 - English ( Rev A )", page 6-2.

 

"With the Amp in Pre, as shown above, the single amp feeds both Paths A & B."

 

Attached File  amp-mono.png   39.94KB   0 downloads


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#6 hurghanico

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Posted 07 April 2014 - 06:33 AM

2nd picture: tube drive applied ONLY over path A, path B carries pure guitar signal.

 

yes John, but in the case of berkleegrad path B isn't carrying anything because he isn't using input 2, and there isn't any amp, just its empty slot


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#7 jandrio

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Posted 08 April 2014 - 01:27 AM

nico, after each "null" amp block the signal sums up 2 mono.

so, in pictue 2 abv, regardless if input2=zero, path b is still fed with unprocessed guitar signal.

however, things would be different if the amp block was placed after the mixer (c attached pic).

Attached Files


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#8 hurghanico

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Posted 08 April 2014 - 02:35 AM

nico, after each "null" amp block the signal sums up 2 mono.

so, in pictue 2 abv, regardless if input2=zero, path b is still fed with unprocessed guitar signal.

however, things would be different if the amp block was placed after the mixer (c attached pic).

 

no John, I just tried on my POD and I confirm that after the null amp there isn't any mono summing..

and also there isn't any unprocessed raw signal going through path B


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#9 jandrio

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Posted 08 April 2014 - 02:39 AM

ok nico, trial (...'n error) is always the best way to find out anything u are searching 4.
can u pls also try the config of the pic I attached (amp after mixer) to verify any differences?
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#10 hurghanico

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Posted 08 April 2014 - 02:46 AM

ok nico, trial (...'n error) is always the best way to find out anything u are searching 4.
can u pls also try the config of the pic I attached (amp after mixer) to verify any differences?

 

tried now, no differences..

 

as expected, the null amp is only a non existent amp, is just an empty slot like the other empty fx blocks, and it doesn't affect at all the signal passing through it


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#11 berkleegrad

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Posted 08 April 2014 - 03:16 AM

Nico,

 

awesome thank you very much! Here is another +1 on pinning your post > How Has Greatly Improved My Use Of The Hd500  lots of helpful info on the 'single input approach'.

 

As a HD300 owner also - I have indeed noticed how much easier it was to arrive at a great sound - [not necessarily related to this topic - I also really like the flexibilty of being able to send easily send a full cab feed to FOH and another without the cab to my rig. (yes I played for a long time with a FRFR wedge; but, really missed the whole guitar into the amp sound on stage)]

 

Of course as luck would have it, I did come across your thread after I had posted my original question and probablly would have posted anyway since my question was also not just about the placement of the tube drive; but, that there was NO amp in the block and it was as much an observation as anything else.

 

When I was reading your post, I was remembering the epic thread from 2011 > What every HD500 owner needs to know and it's spawn > What every POD HD 500 owner *REALLY* needs to know.    < I am including those references for those who may come later with similar questions - AND as a reminder that many good peeps have been to solve the many secrets of the HD500 and SHARE results about these issues for a long time! thank you for being such a significant contributor. ;)   

(sorry for any typos - my firefox spell check doesn't seem to work in this input box)


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appreciate your indulgence, -Rick

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http://groovetherapy.us/

 

 


#12 berkleegrad

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Posted 08 April 2014 - 03:23 AM

Jandrio,

 

appreciate your contibution to the conversation - and there is alway good council in the 'suggestion' to RTFM (your first post) -  reading the freekin manual is an often overlooked source of info which I am often guilty.

 

I will later also try and confirm or deny that a blank amp block sums to mono - though Nico has a lot of trial and error invested in sharing his info and as I grow lazier i tend to defer to other's experience =:o

 

again, thank you for your input.


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appreciate your indulgence, -Rick

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Rick Richbourg

http://rickrichbourg.com/

http://www.facebook.com/rickrichbourg

http://groovetherapy.us/

 

 


#13 hurghanico

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Posted 08 April 2014 - 03:35 AM

Nico,

 

awesome thank you very much! Here is another +1 on pinning your post > How Has Greatly Improved My Use Of The Hd500  lots of helpful info on the 'single input approach'...

 

you're welcome :)

 

I'm glad you found my post useful..


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