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Reamping - YouTube video: what do you all think?

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Reamping - YouTube video: what do you all think?

Postby garrettendi » Thu Jun 14, 2018 12:44 pm

Off the back of the conversation about reamping last week I found this YouTube video (not my own video so no self-promotion!): https://youtu.be/b1O_5gaX4-s

What do you guys all think? As I said before, if I do reamping I plan to plug the send/output of my multitrack or AI directly into the amp with the possibility of buying the Orchid Amp Interface at a later date.

But the noise they are getting with this is unbelievable! To my ears the tone of the music itself is fine, but the noise is bordering on ridiculous. One commenter suggested this could be a ground hum issue which I think would then be made better by sharing a powerstrip.

What do you guys think about the video? Personally I think he should have given more detail about that ground hum.
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Re: Reamping - YouTube video: what do you all think?

Postby The Elf » Thu Jun 14, 2018 1:24 pm

garrettendi wrote:the noise they are getting with this is unbelievable!
...which is precisely why a proper re-amp box is a good idea.

When I see people discussing using two DI boxes and soldering up padded cables I really wonder where sanity went. A re-amp box from Orchid is less than the price of two semi-decent DI boxes! Good grief! :roll:
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Re: Reamping - YouTube video: what do you all think?

Postby garrettendi » Thu Jun 14, 2018 1:25 pm

The Elf wrote:A re-amp box from Orchid is less than the price of two semi-decent DI boxes! Good grief! :roll:

Agreed! It's on my to-buy list!

But you disagree that the noise is due to grounding?
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Re: Reamping - YouTube video: what do you all think?

Postby The Elf » Thu Jun 14, 2018 1:28 pm

garrettendi wrote:But you disagree that the noise is due to grounding?
I don't know, but when the potential solution is the price of curry for four I see no point trying to squirm around it.

garrettendi wrote:It's on my to-buy list!
Then you'll be fine - let others worry about it! :lol:
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Re: Reamping - YouTube video: what do you all think?

Postby Hugh Robjohns » Thu Jun 14, 2018 2:06 pm

garrettendi wrote:But the noise they are getting with this is unbelievable!

He was clearly running the amp pretty loud -- 118dBA SPL at a foot! -- and we don't know the condition -- how noisy -- the amp really is anyway.

The buzzy direct cable is clearly a ground-loop problem which he spectacularly failed to comment upon -- even though it is one of the most important reasons for using a reamp box at all!

But I'm not convinced the guy actually understands the technicalities of what is involved in reamping, or if he does, his technical descriptions appeared both confused and confusing...

In particular, he seems to have no understanding about gain structures and signal-to-noise ratios, and his comments about word length and resolution were rather misleading when what he really meant was a compromised signal-to-noise ratio. the point being that exactly the same noise floor problem would have existed in an all-analogue systems.

Basically, he needed to send a mic-level signal into the JDI passive DI box in order to get an instrument level signal out of it. So he needed to pad the balanced line level from his interface down by 30dB or so. (He seemed aware that his proper reamper introduced 28dB of attenuation, but then bizarrely made a pad cable for the JDI with only 18dB of attenuation. WTF?)

In short, reamping with the correct technology used in the correct way will not add any noise, and is often actually quieter than when plugging a guitar in direct!

Beware what you read, see and hear on the internet... :-)

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Re: Reamping - YouTube video: what do you all think?

Postby garrettendi » Thu Jun 14, 2018 3:05 pm

Good advice there Hugh. Someone like that guy sounds very credible to someone with my level of experience.
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Re: Reamping - YouTube video: what do you all think?

Postby CS70 » Thu Jun 14, 2018 3:06 pm

Nowadays making a video about something is easier than knowing the something :D
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Re: Reamping - YouTube video: what do you all think?

Postby Kwackman » Thu Jun 14, 2018 3:13 pm

CS70 wrote:Nowadays making a video about something is easier than knowing the something :D
:clap:
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Re: Reamping - YouTube video: what do you all think?

Postby garrettendi » Thu Jun 14, 2018 3:14 pm

I'm clearly doing my career all wrong. I should make videos about amateur brain surgery.

I mean, how hard can it be?
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Re: Reamping - YouTube video: what do you all think?

Postby Hugh Robjohns » Thu Jun 14, 2018 3:18 pm

He's obviously well meaning and may well be a perfectly knowledgable guy with lots of studio experience... but IMHO he made a complete pig's ear of the explanations.

You can use a passive DI box in reverse for re-amping (but not an active box because the electronics won't work the wrong way around).

However, a passive DI box is designed to accept an unbalanced instrument level input signal and convert it to a balanced mic level output signal, so using it backwards means you need to feed it with a mic level signal to get an instrument level out to feed the amp...

...and the problem with that is that the output from your interface or mixer is balanced line level, not mic level.

Obviously you could just turn down the send level from the interface, but you'll have to turn it down by as much as 30-50dB which (a) will be difficult (as the control will be near the end stop) and (b) will massively compromise the signal-noise ratio of the analogue output giving you a noisy source for your guitar amp (which won't be helpful if you're planning to compress the signal in the mix!).

So what you really need to do is pad down the interface's line level output between the interface and DI box.... which you could achieve by building a simple balanced resistive attenuator (an H pad or similar) into a special cable, or by buying an XLR adaptor pad -- both providing around 30-40dB attenuation.

However, buying a proper reamper box will cost about the same, and that will use a more appropriate transformer and take care of the attenuation with a handy local level adjustment control. Plus it will include the ability to separate source and destination grounds, and flip the signal polarity too...

And lo, the Orchid reamper was born... (amongst many others)....

The alternative idea of using a direct cable is almost guaranteed to cause ground-loop problems, and has issues with balanced/unbalanced interfacing as well as inappropriate signal levels.

Plug-in impedance-converting transformer adaptors deal with the balanced/unbalanced issue, but not the signal level mismatch, and (usually) maintain a ground connection between input and output causing ground-loop issues again.

So, really, it's a no-brainer to use a proper reamper designed specifically for the job in hand, with the right input and output conditions, and the right facilities for trouble free use.

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Re: Reamping - YouTube video: what do you all think?

Postby garrettendi » Thu Jun 14, 2018 3:22 pm

Hugh Robjohns wrote:The alternative idea of using a direct cable is almost guaranteed to cause ground-loop problems, and has issues with balanced/unbalanced interfacing as well as signal levels. Plug-in impedance-converting transformer adaptors deal with the balanced/unbalanced issue, but not the signal level and (usually) maintain a ground connection between input and output causing ground loop issues again.

So, really, it's a no-brainer to use a proper reamper designed specifically for the job in hand, with the right input and output conditions, and the right facilities for trouble free use.

I'm a little confused here. Yes, I agree that the Orchid Amp Interface is the tool for the job, and it's on my list! But I thought in the other thread it was suggested that a direct cable from either the unbalanced Send Effects on the Tascam DP-24SD or the unbalanced RCA outputs on the Behringer UMC204HD could do the job for now, as long as I watch the levels (and presumably use the same powerstrip for ground)?
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Re: Reamping - YouTube video: what do you all think?

Postby Hugh Robjohns » Thu Jun 14, 2018 3:29 pm

garrettendi wrote:I thought in the other thread it was suggested that a direct cable from either the unbalanced Send Effects on the Tascam DP-24SD or the unbalanced RCA outputs on the Behringer UMC204HD could do the job for now, as long as I watch the levels (and presumably use the same powerstrip for ground)?

I thought we agreed it was a temporary bodge that stands a reasonable chance of working... but you may have small problems with levels and ground-loops.

You have the advantage in your scenario that you aren't dealing with a balanced output at full line level. Instead, you have an unbalanced signal at a nominal -10dBV (-8dBu) which is a hot-ish instrument level already, so turning down the effects send level a bit should get the signal into the right ball-park without compromising the signal-to-noise ratio too much.

Ground-loops could still be problematic, but if the Tascam is a class-II (double-insulated) device you won't have a problem (obviosuly as there's no mains safety earth connection to form the loop), and if you plug the amp and recorder/interface into adjacent mains sockets you might get away with it anyway.

But connecting via a proper reamper will avoid all the potential problems, and afford much greater compatibility with future interfaces and recorders etc....

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Re: Reamping - YouTube video: what do you all think?

Postby garrettendi » Thu Jun 14, 2018 3:30 pm

Understood now Hugh.

I realise it may work as a temporary measure, but a reamp box is strongly encouraged
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Re: Reamping - YouTube video: what do you all think?

Postby Funkyflash5 » Tue Jun 19, 2018 1:54 am

As someone who has a passive di, and 30db worth of inline xlr pad from an unrelated bit of bodging, I'm inclined to give this a try just to see if I can put the 90 bucks into a mic stand or something instead of a reamp box.
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Re: Reamping - YouTube video: what do you all think?

Postby ef37a » Tue Jun 19, 2018 6:25 am

Funkyflash5 wrote:As someone who has a passive di, and 30db worth of inline xlr pad from an unrelated bit of bodging, I'm inclined to give this a try just to see if I can put the 90 bucks into a mic stand or something instead of a reamp box.

Well, you certainly cannot do any harm. To be fair to the guy in the video, he did say he goes for the $100 re-amp box. He also mentions "soddering" (which COULD be misconstrued here!) ? Well if you can solder, all you really need is a log pot in a tin of about 22k and an earth lift switch. An RF 'keeper' cap of about 1nF is also a good idea, but better to get a decent unit like the Orchid.

Regarding 'reversed' DI boxes. I once had a friendly but rather protracted argument on a forum with a well respected studio guy in the States to the effect that he claimed a guitar amplifier, especially a valve amplifier, MUST be driven from a high impedance and so you must use two passive DI's and link them with a mic cable. He was of course confusing the technique of feeding an amp from a control room via a balanced line. (were the Who first to do that?)

He eventually cottoned on when I pointed out that people had been feeding guitar amps from SState pedals which have an output resistance of only 1k, often less!

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Re: Reamping - YouTube video: what do you all think?

Postby Martin Walker » Tue Jun 19, 2018 4:00 pm

ef37a wrote:He also mentions "soddering" (which COULD be misconstrued here!)

Quite a few Americans seem to pronounce it that way on YouTube videos Dave! :headbang:


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Re: Reamping - YouTube video: what do you all think?

Postby ef37a » Tue Jun 19, 2018 5:12 pm

Martin Walker wrote:
ef37a wrote:He also mentions "soddering" (which COULD be misconstrued here!)

Quite a few Americans seem to pronounce it that way on YouTube videos Dave! :headbang:


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Oh yes! I knew that. I have watched every episode the The Big Bang T at least once!

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