Difference between Radial ProDI Jensen and Radial JDI?

[heisleyamor]

in other words...is it worth getting the Radial JDI when the Radial ProDI (also jensen transformer) is 120 dollars less (on mercenary audio)...or maybe even the J48...I still haven't decided what would sound best for my Fender Jazz Bass

[heisleyamor]

bump...if you know if there is a difference in quality...let me know..if there are just extra features with the JDI then I'll probably just get the ProDI...cuz all I need it for is to get some better sound quality out of my bass and keyboard

[lowfreq33]

The pro di is actually the newer one, but the JDI would be considered better. I've never used the pro, but boy, that JDI sounds good.

[nynofi]

Only the JD(JDI, Duplex, JD4, JD6) series boxes have Jensen transformers.

[heisleyamor]

Oh okay...I read on an ebay item that the prodi has a jensen transformer also...but i guess it doesn't...So is there a huge difference in sound quality between the prodi and the JDI? I really like the price of the proDI...is it gonna be a big difference from just going from bass to the instrument line in on my firepod?

[warhead]

The ProDI uses a Chinese built transformer.

The ProDI doesn't have the depth and presence of the Jensen equipped JDI.

The ProDI is good in its price range, but pales by comparison I am sorry to say.

The ProDI is noticeably darker up top by comparison as well.

The JDI is my favorite passive DI, period.

War

[Migs]

Can you tell us what is the model of that Jensen transformer in the JDI then?
Please. I will just call Jensen order the tranny and get rid of the chinese one in my Pro DI and be happy.

Thanks

[AstralPStudios]

I've used the ProDI and it's mostly flat with just a wee bit of top end boost.

(interesting that you say it's darker warhead)

Then again I only used them in a live situation, not studio.

[Jim Williams]

Jensen JT-DB direct box transformer. it's about 12/1 ratio. It's input impedance is medium so it's not a great choice for passive electric guitars as it will load down the pickups and reduce the top end. Active instruments and keyboards work fine.

Contact Jensen Transformers to order the replacement, it's fits right in.

Jim Williams
Audio Upgrades

[Migs]

Thank you very much Mr. Williams

I will call Jensen and try that as soon as I have the time.
There's always something that can be improved in those little
commercial devices.

Migs

[MadR]

Originally Posted by Migs

Thank you very much Mr. Williams

I will call Jensen and try that as soon as I have the time.
There's always something that can be improved in those little
commercial devices.

Migs

And?

Also Jim is it a big difference? I mostly use synths and drummachines.

[Bonemeister]

Hi Guys... just to clarify.

The Radial JDI employs a Jensen JT-DBE while the less expensive ProDI employs a proprietary transformer that is made in Taiwan for us. The JDI is linear from 10Hz to 40kHz while the ProDI is linear from 20Hz to 18.5kHz.
Both exhibit excellent phase response. In listening tests, the most discerning ears will be able to hear the difference. The advantage with the JDI and Jensen Transformer is that it reaches into the higher harmonics that one can compare when recording at 96kHz versus 48kHz. It is better, more features, but alas more expensive!

[Bonemeister]

Just one more point...

When you hit an active circuit hard with lots of level, the circuit is limited by the headroom. The headroom is dictated by the power supply. Active DI boxes are in fact preamplifiers and subject to the same limitations. When you exceed the headroom, the active circuit clips the transient and the result is a square wave.

Transformers do not behave like this. They do not so much 'distort', they saturate. When you hit a transformer hard, it will naturally round out the transient, acting like a soft limiter. Folks often say that the Radial JDI sounds 'vintage'. This is a plesant artefact of the transformer. Higher quality transformers produce what is known as a warm Bessel curve.

A good passive DI sounds really nice on digital sources like synths and digital pianos. The quality of the signal is determined by the circuit design, filters, and of course the transformer. Nickel based cores as used in our passive devices work well as they do not introduce group delay or phase distortion in the cirtical listening range.

Have fun!

[Ruudman]

Peter and others, if I use a buffer before the JDI (i.e a pedal of some sort), will then the transformer stop loading the passive pickups?

[Jim Williams]

Yes, a low output impedance buffer, wherether internal to the instrument or external will prevent transformer primary loading. If external, it's best kept close to the instument as cable losses will occur. Otherwise the low input impedance will load passive guitar pickups and you will hear a top end roll-off.

I find my active, low output impedance guitars do not need DI's at all. I just feed them right into the line level 15k input impedance of the console to make up some gain before conversion, for clean direct signals. Same applies to bass guitar, it's fed into a line stage, I take 15 db gain and feed the Aphex 651 then it's on to conversion. The active instruments have output levels far above that of a passive electric guitar, they even drive headphones from the instrument jacks.

I havn't used a dedicated DI in many years here, I have alternate high impedance line gain amps that do the job without the gain shifts that occur with DI's.

For best signal to noise ratios, take gain up front to overcome downstream system noise. The active buffers with gain allow the instruments to output line levels before any external gain is applied. I've used that technology since 1972 and it can be heard on the Mahavisnu Orchestra albums and most of Frank Zappa's mid 1970's work onward. Other examples are found on Stevie Wonder's Hotter Than July and later releases.

Jim Williams
Audio Upgrades

[Bonemeister]

Regarding your question:

Originally Posted by Ruudman

Peter and others, if I use a buffer before the JDI (i.e a pedal of some sort), will then the transformer stop loading the passive pickups?

Mr. Williams is correct. Let me answer this is a different way.

When you put a buffer in between the pickup and a passive direrct box like the Radial JDI, the buffer will then lower the impedance and allow you to run long distances. The buffer will at the same time eliminate loading on the pickup.

Where things get interesting is the quality of the buffer. This is in fact why most guitarists prefer to employ true bypass pedals. They hate the sound of buffers. This is because most buffers are not well designed, are compromised to work on batteries and so forth. A good sounding buffer can further be improved by being able to modify the load on the pickup so that it sounds natural. We have found that 1 meg-Ohm buffers tend to sound glassy and 'active' on passive pickups while a lower impedance around 220k-Ohms sounds more natural. Drag Control load correction was developped after doing lots of listening tests.

We must also keep in mind that when driving signals long distances - say 100 meters or 300 feet from a stage - balancing the signal goes a long way at eliminating noise and avoiding pollution from electromagnetic fields. This is why telephone companies have been using balanced lines for the past 100 years and why DI boxes are used in live touring. A DI also lowers the impedance.

[smokapot]

Does this mean my J48 sucks and I should have bought something else?

I did research as much as I could and at the time about 3 years ago I decided the J48 would work fine (now IM second guessing myself)

Maybe it was price, I cant remember now.

I'll check......

Anyway the J48 works for me.

[Jim Williams]

To add further: Electric guitars use passive volume/tone networks. Those also load down the signal from the pickups. For the purest tones, those should be removed as a 250k pot as used on a Fender guitar will also load down the pickups. The reason the strat's bridge pickup has that extra bite compared to the middle/neck pickups is because of the passive tone controls are loading down the top end of the those pickups.

1 meg ohm input impedance line amps are affected by the passive volume/tone controls. Adding additional loading to a DI box does not take the instruments internal loading into consideration as a Fender Strat will already have the 250k load from it's passive volume control. With the 250k tone control added, real world loading is reduced to 125k ohms. A frequency sweep on the Audio Precision shows those pickups will right turn downward past 1 k hz, that is a severe roll-off. Remove that loading and restore the 1 meg ohm input impedance and you will see the true frequency response of the pickup with it's resonant peak. On a strat pickup it's about + 3 db at 8k hz.

Fender offers a no load tone control as an aftermarket product. It's a 250k tone pot with a switch that cuts it out of circuit when full up.

On my active instruments, the preamp output feeds a 10k log Bourns conductive plastic volume pot. It's a smooth as a quality fader. It also retains an identical tone whether on 10 or 2. It avoids the hf roll-offs that occur when you lower the volume on a passive guitar. They drive amps hard and fat. The clarity is stunning and it's a very full sound.

I can't play passive guitars, too whimpy and small sounding. All active since 1972.

Jim Williams
Audio Upgrades

[Bonemeister]

Originally Posted by smokapot

Does this mean my J48 sucks and I should have bought something else?

I did research as much as I could and at the time about 3 years ago I decided the J48 would work fine (now IM second guessing myself)

Maybe it was price, I cant remember now.

I'll check......

Anyway the J48 works for me.

The Radial J48 is active while the Radial JDI is passive. The following two videos have been posted to explain the difference and benefits of each.

YouTube - Radial j48 advanced active direct box - explained
YouTube - The Radial JDI explained

The J48 is a great choice for electric guitar.

[smokapot]

Thanks Bonemeister, thats what I use mine for mostly, probably why I got that one.

[Neilo75]

Hey Peter/others if I'm recording an electric guitar (gibson SG) direct into a computer (to use with guitar rig 4) would a passive direct box like a JDI work well or should I use an active direct box instead? My soundcard (delta 44) doesn't have phantom power so I'm guessing I can't use the J48? Or is there something better?

I'm not looking to colour the sound just get it into my DAW.

[Bonemeister]

Selecting the right direct box for direct-to-computer recording is a matter of preference and budget.

For the purist, the Radial JDV is probably the best choice for several reasons: first, it is class-A which means that it employs a single buffer to drive the signal as opposed to most interfaces that employ class AB type operation. Next, because it is completely void of negative feedback loops, there is no circuit stabilizing phase cancellation in the audio path. This means that it will deliver the most accurate representation of the instrument. And with variable load correction, you can dial in the sound of the guitar so that it sounds natural. The JDV comes with an external power supply.

The Radial J48 is often the next best choice Radial J48 but it requires phantom power or a battery (you need to add a 9V battery wire-adaptor). The impedance is in the 220-ohm sweet spot which makes it sound great. Although class AB, the J48 sports exceptional specifications including low phase distortion, low IMD and wonderful cascade of even order harmonics.

If phantom is not an option, then the Radial JDI or ProDI will serve you well. These passive boxes will provide a good interface to your mic preamp and because your are connecting direct to the computer, there will not be any additional load going into a guitar amp.

Note: In all cases, a direct box is designed to connect to a mic preamplifier or microphone input. Most are equiped with phantom power.

Have fun!

Peter

[Neilo75]

thanks Peter! thumbsup

Exactly what I wanted to know. I wasn't sure how the JDV/J48/JDI would go with guitar as opposed to bass as everyone seems to generally mention bass when discussing direct recording with a DI.