REDDI Tube DI Mega-thread-III

[Kro]

...and doesn't have much in the way of secrets.

Or does it?

I’ve been reading through a number of threads on it, and some seem to think that it adds a good bit of flavor (at least for a DI). I’m very curious as to how it emphasizes harmonics, by how much, and if it actually does alter the frequency curve when all is said and done – either just as a byproduct of those harmonics, or if there may be something else going on.

Given its reputation, it’s something that I’ve been fascinated with for a bit, and finally have managed to get my hands on one to experience it for myself.

My curiosity is probably similar to yours when you compared it to your VT Deluxe (I very much enjoyed that comparison by the way)… but I also have access to, and a very, very low level of proficiency with spectrum analysis software.

 

[beans-on-toast]

A REDDI plugin. At $49, a lot less than the hardware. Adds a low end shelfing tone control. It came out last spring from what I understand. Anyone tried it?

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[JimmyM]

A REDDI plugin. At $49, a lot less than the hardware. Adds a low end shelfing tone control. It came out last spring from what I understand. Anyone tried it?

[Invalid or Expired Link Removed]

Adds a lot of other stuff, too. Almost isn't a REDDI with all that extra stuff

 

[beans-on-toast]

Adds a lot of other stuff, too. Almost isn't a REDDI with all that extra stuff

I find with a lot of plugins that it’s best to look at them a tools, are they useful. Not necessarily, is it exactly the same. The distortion on it’s own can be extreme at some settings but it can be dialed in to add some dirt and fit well into the mix.

They modeled the REDDI, the basic curves of the REDDI are interesting.





I wonder if A-designs sanctions this. I didn’t see any mention of the plugin on their web site.

 

[svtb15]

I will Guess that Harmonic Emphasis may be due to the REDDI running louder and pushing the input of the Channel strip or Preamp it is feeding..
I have an API 512 and a BAE NEve 1073 Clone,Both the API and BAE have HIGH headroom.
If i run the REDDI;s output up LOUD.. it will create increased tonal changes into each preamp differently. But its from driving the preamp and not the REDDI..

The neve clone ads a lot of beautiful colori Thick and warm and wide.. Where the API seems more like teh REDDI but gained up to drive my converters of even a tape machine.
But to me the REDDI doesn't seem to add harmonic enhancement .. The VOL on the REDDI is just clean GAIN . POST the OT.. The transformer is already being hit with steady signal from the tube circuit... The VOL control is just the gatekeeper.

Or does it?

I’ve been reading through a number of threads on it, and some seem to think that it adds a good bit of flavor (at least for a DI). I’m very curious as to how it emphasizes harmonics, by how much, and if it actually does alter the frequency curve when all is said and done – either just as a byproduct of those harmonics, or if there may be something else going on.

Given its reputation, it’s something that I’ve been fascinated with for a bit, and finally have managed to get my hands on one to experience it for myself.

My curiosity is probably similar to yours when you compared it to your VT Deluxe (I very much enjoyed that comparison by the way)… but I also have access to, and a very, very low level of proficiency with spectrum analysis software.

 

[beans-on-toast]

Yes, what is called the “volume” control on the REDDI is actually an attenuator, not a volume.

 

[JimmyM]

I find with a lot of plugins that it’s best to look at them a tools, are they useful. Not necessarily, is it exactly the same. The distortion on it’s own can be extreme at some settings but it can be dialed in to add some dirt and fit well into the mix.

They modeled the REDDI, the basic curves of the REDDI are interesting.




I wonder if A-designs sanctions this. I didn’t see any mention of the plugin on their web site.

They're using the A-Designs logo, but I am so not buying into that low end cut they show in the first graphic when you turn it on, and the guy narrating the video starts right off with wrong info about the REDDI's bass knob being broken at the studio he used it at (there's no bass knob). After that I quit watching. Might still be a very good plugin, but dang, not a good way to start off your demo video for it.

 

[Kro]

But to me the REDDI doesn't seem to add harmonic enhancement

It definitely does. That's actually most of what it does from what I can tell so far - as in I haven't found any other affect just yet, but I've yet to dive into more complex effects that might be time based (the type of thing a waterfall plot would show). Regardless, I spent a good bit of time putting it through its paces last night, and if it does nothing else, it strongly emphasizes the 2nd harmonic - even without a very strong signal.

To the best of my knowledge, this isn't anything atypical for tube based sources of harmonic enhancement, but compared to other (solid state) sources of drive I'm familiar with, this seems to be the big difference - a very strong 2nd harmonic while carefully controlling/downplaying additional harmonics further down the line. I'm sure that to many this comes as no surprise.

I can get something like my VTDI to match that 2nd harmonic similarly, but at that point the 3rd is already roaring.

Give that that 2nd harmonic is usually more associated with “fatness” than distortion, I don’t find that assessment surprising at all given the way that people describe the tones of the REDDI.

Looking forward to playing around with it more tonight, and maybe if I'm feeling brave, eventually doing some actual recorded comparisons to share.

 

[beans-on-toast]

When being driven, tubes have excursions on an operating curve. There are linear and non linear regions along this curve. Excursions into a non-linear region can produce distortions such as harmonics.

Where the tube is biased in the linear region and how far the excursions are dictate how much and what type of distortions will be produced. Harmonics are one type, there are others that provide dirt. Note that the output transformer itself and how it interacts with the tube also contributes to the sound. A good output will not smear chords, the notes will sound distinct.

So, if you drive a tube, you get into harmonics and distortion. How much depends on the design. If you play conservatively, you might not hear much harmonics in some amps.

Different players will hear different things depending on how hard they and their instrument is driving the input and their playing style.

 

[Kro]

So, if you push a tube hard, you can get into harmonics and distortion. How much, if any, depends on the design. If you play conservatively, you might not hear harmonics in some amps.

Different players will hear different things depending on how hard they and their instrument is driving the input and their playing style.

Absolutely, and I'm not trying to take away anything away from any perceptions that I completely trust.

I'm just noting that as far as I can tell objectively, the 2nd harmonic presents itself even with a conservative signal. Perhaps below the audible threshold or not easily noticed, but easily summoned.

 

[beans-on-toast]

Absolutely, and I'm not trying to take away anything away from any perceptions that I completely trust.

I'm just noting that as far as I can tell objectively, the 2nd harmonic presents itself even with a conservative signal. Perhaps below the audible threshold or not easily noticed, but easily summoned.

That’s part of the color or character emparted by the design. Tubes have a lovely way of doing this.

 

[Kro]

That’s part of the color or character emparted by the design. Tubes have a lovely way of doing this.

100% agree!

 

[Mark Reccord]

The position of the pot in the circuit definitely does affect harmonic content and I would suggest that it increases as you turn it down because that has the effect of increasing the AC load (ie dropping the impedance the plate sees) on the tube which does indeed increase harmonic content below clipping. I'm running my box with both gain and output pots with the output pot wired in the same way as on the REDDI and I also have a switch that bypasses the output pot. It's most couloured with the input gain up all the way and the volume controlled with the output pot and least coloured with the output pot bypassed. There's not enough gain in the first stage for it to clip the output stage (12au7) with any of my instruments so I do think the change in character is due to the output pot loading the second stage. I'd hazard it's the same in the REDDI. It's around .7% THD with the pot bypassed, 2% with it in circuit but all the way up and over 5% with it almost all the way down according to my (admittedly crappy) analyzer.

 

[svtb15]

Waterfall plots etc That's pretty cool! However, to date I have had at least 4 grammy winning engineers and producers listen to my REDDI while working. As well as one of the world most famous mastering engineers up in the state of Maine that worked with my reddi. You know who it is. ORIGINAL Tube too.. .
It depends what you are driving with that 16+db of gain or less.
Evch one of them told me leave it at 12 o'clock, there was no discernible difference in sound..

For teh fun of it. I am going to try to run my REDDI at full blast the next few sessions to see what they say of think .. Since I have two and if I'm allowed to experiment I will split the signal and send one at my normal setting too.
When on a session like that Its not a good idea to want to experiment.. They like to have confidence that YOU have confidence to send they what they want without hesitation. So i have to feel the waters first

It definitely does. That's actually most of what it does from what I can tell so far - as in I haven't found any other affect just yet, but I've yet to dive into more complex effects that might be time based (the type of thing a waterfall plot would show). Regardless, I spent a good bit of time putting it through its paces last night, and if it does nothing else, it strongly emphasizes the 2nd harmonic - even without a very strong signal.

To the best of my knowledge, this isn't anything atypical for tube based sources of harmonic enhancement, but compared to other (solid state) sources of drive I'm familiar with, this seems to be the big difference - a very strong 2nd harmonic while carefully controlling/downplaying additional harmonics further down the line. I'm sure that to many this comes as no surprise.

I can get something like my VTDI to match that 2nd harmonic similarly, but at that point the 3rd is already roaring.

Give that that 2nd harmonic is usually more associated with “fatness” than distortion, I don’t find that assessment surprising at all given the way that people describe the tones of the REDDI.

Looking forward to playing around with it more tonight, and maybe if I'm feeling brave, eventually doing some actual recorded comparisons to share.

 

[svtb15]

I hope i read you correctly. .But The REDDI should NOT have a 12 au7

The position of the pot in the circuit definitely does affect harmonic content and I would suggest that it increases as you turn it down because that has the effect of increasing the AC load (ie dropping the impedance the plate sees) on the tube which does indeed increase harmonic content below clipping. I'm running my box with both gain and output pots with the output pot wired in the same way as on the REDDI and I also have a switch that bypasses the output pot. It's most couloured with the input gain up all the way and the volume controlled with the output pot and least coloured with the output pot bypassed. There's not enough gain in the first stage for it to clip the output stage (12au7) with any of my instruments so I do think the change in character is due to the output pot loading the second stage. I'd hazard it's the same in the REDDI. It's around .7% THD with the pot bypassed, 2% with it in circuit but all the way up and over 5% with it almost all the way down according to my (admittedly crappy) analyzer.

 

[svtb15]

My OLD home rack or preamps. .I USED to feed my Old API pre from my REDDI. I sold these and got a 500 series 512.. I don't need all the channels anymore .. API 3124 is the top rack..
It was great.... YOu can open them up and hit them hard and they only get better sounding.
To me the REDDI is closer to an API thng than a Neve thing..
I only now have a neve clone by BAE.. Very good unit and quieter than my old neve from the 70s.

 

[Mark Reccord]

I hope i read you correctly. .But The REDDI should NOT have a 12 au7

It doesn't have 2 gain stages either.

I was referring the box I designed myself using a 12au7. There is definitely a discernable difference in sound with the position of the output pot in my DI and a measurable difference in distortion and the output pot is wired exactly as in the REDDI so I'd expect the same thing. I haven't been able to actually test a REDDI, though.

 

[svtb15]

Ok I was wondering... what you were referring to with the 12au7 and a REDDI.. Now i see what you meant.

It doesn't have 2 gain stages either.

I was referring the box I designed myself using a 12au7. There is definitely a discernable difference in sound with the position of the output pot in my DI and a measurable difference in distortion and the output pot is wired exactly as in the REDDI so I'd expect the same thing. I haven't been able to actually test a REDDI, though.

 

[Kro]

Evch one of them told me leave it at 12 o'clock, there was no discernible difference in sound..

Oh yeah, I actually didn't mention the level knob at all in my posts personally, but I did look into it.

My assessment: the signal does some wonky things at the extremes (might have been due to outside factors), but within say 9:00 to 3:00 (or a little wider range), there was very very very little difference aside from level, and not the type that would be IMO noticeable by ear.

It was one of those things where I looked into it, went "OK then", and then moved onto more interesting aspects.

Edit: just to be clear, the harmonic emphasis comes into play solely based on the strength of the input signal. The level knob of the REDDI has an extremely minor effect, but it was so minor that I wouldn't expect it to be noticeable unless somebody was actually looking for it on a plot (like me)!

 

[beans-on-toast]

Waterfall plots etc That's pretty cool! However, to date I have had at least 4 grammy winning engineers and producers listen to my REDDI while working. As well as one of the world most famous mastering engineers up in the state of Maine that worked with my reddi. You know who it is. ORIGINAL Tube too.. .
It depends what you are driving with that 16+db of gain or less.
Evch one of them told me leave it at 12 o'clock, there was no discernible difference in sound..

For teh fun of it. I am going to try to run my REDDI at full blast the next few sessions to see what they say of think .. Since I have two and if I'm allowed to experiment I will split the signal and send one at my normal setting too.
When on a session like that Its not a good idea to want to experiment.. They like to have confidence that YOU have confidence to send they what they want without hesitation. So i have to feel the waters first

I don’t think that anyone is knocking the REDDI.

Both Bob and Adam seem to be nice people. There were recent videos interviewing them. I’m amazed that Bob can still do what he does. At 74, most are not able to.