The best DI box for bass

[JimmyM]

A well designed DI does not make sound at all. A well designed DI provides a maximum of signal to noise ratio by a minimum of THD which means linear and nonlinear distortion.
So a well designed DI does make NO SOUND,

Sounds like a DI I'd throw in the trash.



Those types of DI's are what has made me dislike DI's in general. I call it the "banjo effect," where the bass ends up sounding like a low pitched banjo on the high notes. I want some low end whoomp on the high notes and hate it when it's not there.

 

[Matt R]

It's my 6SL7 preamp/DI that I affectionately call the "Box-O-Tone".

Here's a clip:



Sounds GREAT to me! Nice, man. Thanks for sharing.

 

[svtb15]

+1

Sounds like a DI I'd throw in the trash.



Those types of DI's are what has made me dislike DI's in general. I call it the "banjo effect," where the bass ends up sounding like a low pitched banjo on the high notes. I want some low end whoomp on the high notes and hate it when it's not there.

 

[James Simonson]

Here's a couple DIs I put together. The one on the right is made from a giant Newcomb transformer pulled out of a very old console from the 60's with a large iron core. It's a perfect match for a P Bass at 50k. On a scope it was flat all the way down to 20hz!
Ed Wolfrum gave me the schematics/specs to help me put these together. Ed was the chief engineer/console builder at Motown. This one is identical to Jamerson's DI. Turns out, Ed is my neighbor!
It sounds very similar to the Reddi but the output is lower and it's passive.

The one on the left is an active proto type design made from two jfet. Very simple. It will do extremely high impedance's very well. Great with piezo pickups. Nice on the upright pickups and acoustic guitars. Piezo's can actually sound pretty good once they're properly matched.

You can visit Ed Wolfrums site here:

Link Removed

Several of the large passive DIs were recently sold to Abbey Road Studios. They're very expensive. I used them on Dennis Coffey's latest release.

I made a miniature version of the Wolfrum Active DI. I need to find a photo. See next post.

 

[James Simonson]

 

[JimmyM]

Neato! Bet those sound cool.

 

[James Simonson]

JimmyM you're more than welcome to borrow one if you ever pass through Detroit some time.

 

[JimmyM]

Might take you up on that if we ever get up there again. Been years, but we used to play there all the time.

 

[Mark Reccord]

They sound much different when you add several hunderd feet of cable.

They may or may not depending on the output impedance of the instrument and the input impedance of the preamp being driven. This is largely independent of the cable run, rather the turns/impedance ratio of the transformer and the impedances of the things connected on each side of it. Both directions need to be considered. Say we're using a 7:1 transformer like the Lundahl LL1530. Impedance ratio is the square of the turns ratio so 49:1/1:49. If we connect it to a mic preamp with 1k input impedance, the input impedance the instrument sees is 49k. Conversely, if we connect a passive instrument with 10k output impedance, the output impedance the mic pre sees is 204 Ohms. This isn't too bad a ratio and shouldn't load things down very much. Connect an instrument with 50k output impedance and the mic pre suddenly sees 1020 Ohms and on the other side the instrument still sees 49k. 1:1 ratio of output-input impedance will cause lots of signal loading on both sides. This can be mitigated by using a higher ratio transformer like the JDI (12:1) at the expense of signal strength on the mic pre side. I have run into problems getting enough signal at the desk with low output passive instruments into a JDI.

The question of active or passive it all depends on your personal needs.
You can't feed a 300 Watt power amp output signal into any active DI.

Sure you can. Countryman, KT and BSS all offer speaker level inputs on their active boxes and I'm sure others do as well. There isn't really any advantage of using an active box in this situation, though as the output impedance driving the DI is so low as to be negligible.

A well designed DI does not make sound at all. A well designed DI provides a maximum of signal to noise ratio by a minimum of THD which means linear and nonlinear distortion.
So a well designed DI does make NO SOUND,

Depends on the design goals, really. There are instances where "as clean as possible" is useful and ones where "colour added" is desirable.

It's my 6SL7 preamp/DI that I affectionately call the "Box-O-Tone".

Here's a clip:



Several of the large passive DIs were recently sold to Abbey Road Studios. They're very expensive. I used them on Dennis Coffey's latest release.

I made a miniature version of the Wolfrum Active DI. I need to find a photo. See next post.

These are pretty neat too.

I have a couple of prototype ones as well. One's a passive box using that Lundahl transformer I referenced earlier and one's an active box using JFETs on the front end for super high input impedance and a BJT on the back end for low output impedance. Transformer coupled with a the same Lundahl transformer in 3.5:1 mode. It's about equivalent to its peers (J48, Type 85, etc.) in terms of THD and noise, but has much lower IMD than either of those. It can also take much more input signal than the Radial can. I was surprised to see that the J48's rail voltage when phantom powered was ~3V. That doesn't give the input much headroom.

Interestingly, the REDDI is liable to be sensitive to the input impedance of the mic pre as the plate load for the tube is the primary of the output transformer. The AC operating point of the tube will be different with a 1k Ohm mic pre than it will be with 2k. Don't know how much audible difference that might make, but it's likely to be some.

 

[Bassmec]

The best?
Well for me I would have to say the best was already in production at the start of WWII, as in the awesome sounding Harry Olsen designed RCA OP-6 portable amplifier unit.
However if you require a few more bells and whistles I am certain my son Robin Harwood has designed the best DI box for bass at the moment.
As you probably know I come from a large trans Atlantic family of total audio extremist designers and engineers in which we all compete with each other to out doo in East Anglia UK, the work of the other family members from our Florida and US Virgin Islands branch.
So this is the latest british formerly top secret weapon (built without regard to cost), now in production for you to buy:
Link Removed
So eat you heart out DW Fearn VT 15 owners, up until this announcement without doubt the best Mic Pre/ DI box with EQ ETC. you could buy new in one box has been thoroughly trounced by this release.

 

[JimmyM]

I wouldn't even know where to plug into that thing, but it sure looks nice!

 

[John D Harris]

The best?
Well for me I would have to say the best was already in production at the start of WWII, as in the awesome sounding Harry Olsen designed RCA OP-6 portable amplifier unit.
However if you require a few more bells and whistles I am certain my son Robin Harwood has designed the best DI box for bass at the moment.
As you probably know I come from a large trans Atlantic family of total audio extremist designers and engineers in which we all compete with each other to out doo in East Anglia UK, the work of the other family members from our Florida and US Virgin Islands branch.
So this is the latest british formerly top secret weapon (built without regard to cost), now in production for you to buy:
Link Removed
So eat you heart out DW Fearn VT 15 owners, up until this announcement without doubt the best Mic Pre/ DI box with EQ ETC. you could buy new in one box has been thoroughly trounced by this release.

Will it fit on top of KJung's micro amp?

 

[Jeff Bonny]

I wouldn't even know where to plug into that thing

I'm gonna go out on a limb and say maybe the 1/4" jack right in the middle marked "INSTRUMENT"?

but it sure looks nice!

It sure does!

 

[JimmyM]

I'm gonna go out on a limb and say maybe the 1/4" jack right in the middle marked "INSTRUMENT"?

See, I think that's a dodge designed to confuse the issue

 

[Jeff Bonny]

Probably right. Those pom audio engineers are by all accounts a sneaky lot...I bet most of those knobs aren't even hooked up to anything.

 

[Doner Designs]

Any of you separate DI box users going into the box with a speaker level signal instead of instrument level? Looks like several can do that though it eliminates the ability to bypass EQ or pedals. I'm not sure what running through a solid state power amp is going to add. Putting it after a tube amp's power stage could make a lot of sense however. I have one of those little Ashdown 15W all tube amps and it might sound good to feed a DI with the output from that and the 15W is probably enough for use on stage (supported by house).

Separate question - some say you are better off with an active box if you run a passive bass, especially with long cable runs. What if the bass is active but the output level is no higher than a passive (examples would include Audere and the Stingray I used to have). Is it about impedance or output level?

One more - the countryman has an extra pin in the xlr jack. Is that for the phantom power? I don't think I have ever seen an xlr jack or cable that looks like that.

 

[coreyfyfe]

Any of you separate DI box users going into the box with a speaker level signal instead of instrument level? Looks like several can do that though it eliminates the ability to bypass EQ or pedals. I'm not sure what running through a solid state power amp is going to add. Putting it after a tube amp's power stage could make a lot of sense however. I have one of those little Ashdown 15W all tube amps and it might sound good to feed a DI with the output from that and the 15W is probably enough for use on stage (supported by house).

I have a countryman type 85 that I use for that. I like the DI and it's nice to have the full sound of my tube amps sent to the house if that's the tone I'm after. Lately I've been using my SVT-DI instead.

Separate question - some say you are better off with an active box if you run a passive bass, especially with long cable runs. What if the bass is active but the output level is no higher than a passive (examples would include Audere and the Stingray I used to have). Is it about impedance or output level?

I've heard the same, as far as I've heard it usually has to do with output impedance not necessarily signal level, but I'm sure someone else will chime in and correct that if it needs to be.

One more - the countryman has an extra pin in the xlr jack. Is that for the phantom power? I don't think I have ever seen an xlr jack or cable that looks like that.

Which model? Don't think I've noticed an extra pin on mine? There's an extra exposed piece of metal in the back of the connector, I think that's part of the shield/ground connection though...

 

[RobbieNuke]

Any of you separate DI box users going into the box with a speaker level signal instead of instrument level? Looks like several can do that though it eliminates the ability to bypass EQ or pedals. I'm not sure what running through a solid state power amp is going to add. Putting it after a tube amp's power stage could make a lot of sense however. I have one of those little Ashdown 15W all tube amps and it might sound good to feed a DI with the output from that and the 15W is probably enough for use on stage (supported by house).
I've used the attenuated input of a (passive) DI with my older amps (Ampeg SVT, Sunn Coliseum, Acoustic 320) with great results. You feed the FOH exactly what you hear... well a mic in front of the speaker would be EXACTLY what you hear, but you catch my drift. You get all the coloring of pedals/FX, cables, pre-amp, and most of all any power amp distortion!

Separate question - some say you are better off with an active box if you run a passive bass, especially with long cable runs. What if the bass is active but the output level is no higher than a passive (examples would include Audere and the Stingray I used to have). Is it about impedance or output level?
Unless your running >50 feet of cables I wouldn't worry. It's a little bit of both, more about impedance attenuating the HF..

One more - the countryman has an extra pin in the xlr jack. Is that for the phantom power? I don't think I have ever seen an xlr jack or cable that looks like that.

Never saw a CM with 4-pin XLR. Could have been modified to use with old Ampeg gear.

 

[Doner Designs]

Thanks for the replies on my q's!

The Radial JDI seems like a good quality simple mid-priced option. I did get an opinion from someone who will remain nameless that Radial is a cable company and their stuff is not very good. A brilliant guy told me this, but I tend to discount it given all the favorable reviews on TB, artist endorsements and the fact that it seems like they are one of the market leaders for this type of product.

Here is a picture of the Countryman jack. How common would it be for house (small/low budget venue like a church) to have a cable that fits this and what is that big screwdriver sized pin anyway???

I wonder what happens if you send one of these boxes a speaker level signal and forget to flip the toggle switch on the DI from pickup to speaker. Seems like it could fry the box but maybe they are indestructible inside and out.

Cool option to have when used with a tube amp.

 

[svtb15]

Its a normal 3 pin XLR..... that piece of metal is just a flush mounted piece of the housing. It does not mate with the cable at all
. they are pretty indestructible... Ive had mine since 1977... they can tale about a 250V hit to the front end IIRC

If you flipped the switch? mmm Im sure you will OL something .. Blow something up.. Most likely.. Let us know.... But video it so we can see the Poooof too

Thanks for the replies on my q's!

The Radial JDI seems like a good quality simple mid-priced option. I did get an opinion from someone who will remain nameless that Radial is a cable company and their stuff is not very good. A brilliant guy told me this, but I tend to discount it given all the favorable reviews on TB, artist endorsements and the fact that it seems like they are one of the market leaders for this type of product.

Here is a picture of the Countryman jack. How common would it be for house (small/low budget venue like a church) to have a cable that fits this and what is that big screwdriver sized pin anyway???

View attachment 683887

I wonder what happens if you send one of these boxes a speaker level signal and forget to flip the toggle switch on the DI from pickup to speaker. Seems like it could fry the box but maybe they are indestructible inside and out.

Cool option to have when used with a tube amp.