Talk to me about DIs

[Newmarket]

"Your pic shows there's no resist on the PCB, which leaves the copper exposed to oxidation. I must admit it looks somewhat amateur-ish."

+1. Spot On.
Guessing this is quite an old unit ?

 

[Whoops]

Your pic shows there's no resist on the PCB, which leaves the copper exposed to oxidation. I must admit it looks somewhat amateur-ish.

You are correct that the AR117 plug-in board looks amateur but the PCB of the AR116 DI itself is completely different, it professionally made with that green protection on top of the traces. Nonetheless that green protection was falling apart and the traces has a lot of oxidation.
I took sono photos at the time I will see if I can find them.
There’s a thread here with a repair for an Ensoniq DP4 unit that has leaking capacitors and oxidation in the PCB traces, this traces looked similar to the photos on that thread

I've never been impressed by the sound of a DI'ed electric guitar, period;

I feel the same, I tried the two AR116 DI boxes after I fixed them with acoustic guitar and bass and didn’t like the sound, while I normally like those 2 instruments with other DI boxes

for me an electric guitar develops its full potential by making a piece of cardboard move some air. Same for a Fender Rhodes.

I agree, although I love the sound of an electric guitar connected directly to a Mic Preamp cranked up and without any DI in between , it gives a great Fuzz sound, I love it

 

[Newmarket]

I agree, although I love the sound of an electric guitar connected directly to a Mic Preamp cranked up and without any DI in between , it gives a great Fuzz sound, I love it

That's interesting. I usually find that a passive guitar pickup into a mic (I'm guessing c 2K2 input Z) or a line (say 10K) input sounds weak as you might expect. But if you gain it up to "Fuzz" i guess you are getting (sort of) into "Fuzzface" territory where a high Z pickup sees a low input Z and becomes more of a current source (in a hand waving sort of way )
I should give it a try.

 

[Whoops]

That's interesting. I usually find that a passive guitar pickup into a mic (I'm guessing c 2K2 input Z) or a line (say 10K) input sounds weak as you might expect. But if you gain it up to "Fuzz" i guess you are getting (sort of) into "Fuzzface" territory where a high Z pickup sees a low input Z and becomes more of a current source (in a hand waving sort of way )
I should give it a try.

It’s a really cool sound, the Beatles also have some guitars recorded that way, it’s an harsh in your face sound that I personally like.

You can listen to the direct guitar to mic Pre sound in this song, in the main guitar riff/lead starting at 0:15:

 

[midwayfair]

Was short on time for a few days so just catching up. Thanks for the additional suggestions (and the commercial products to look at as well). I ordered some parts that I was short on (... xlrs) to do some experimentation.

If you are talking about piezo pickups, there's a nice situation for DI-DIY (; when deciding to take the "charge amp" route (look at Figure 3).
In my small amateurish experiments it produces a very nice full range sound from the piezo (I just tried with Kalimba...)

Looks like a nice project. Still needs an output section and it does seem like a lot of fuss for a buffer, but I'll need more time to actually read the whole article instead of making assumptions. Can probably still build it on perfboard, which is a plus.

 

[MikelLikesIt]

I’ve come across a gent with a couple versions of the Bo Hansen board, one is very stock with transformer options, and one is a dual version. Hes at proaudiogc.com for your viewing.

 

[midwayfair]

Wanted to document my progress so far, deliberately keeping things about as unsophisticated/simple as possible:



I mostly post guitar pedal stuff on that channel historically (other than my music), so the circuit explanation is geared toward that audience. I think most folks here can just skip to the end of the circuit drawing sections if you're curious about specifics, but both circuits were a 2M2 gate resistor on a FET input; one uses a transformer and the other is the Alice (Schoeps) active output. The transformer is a little UTC transformer I bought here years ago that I've never really decided on a use for. An old thread about them says they can handle -7dB, so I was originally planning on using them in something that would intentionally drive them too hard, and just never got around to using them. I do actually like that it steps down the level a bit, as the Alice circuit is almost too loud, but I'm pretty sure I can find a cheaper (and maybe even smaller) 1:1 or 2:1 transformer for this purpose.

I've drawn part of a layout from the link L´Andratté sent, so I do plan to build one that's op amp based. I also want to try one of the THAT chips for an active output and see if it improves S:N. I've also drawn a layout for the Bo Hansen, but I'm not sure I want to bother boxing up another transformer-based one. (Of course, I could always desolder the circuit board from the box.)

However, I will say: I'm impressed by the sound of the Alice microphone circuit here. The highs are extremely clear, even compared to another circuit with the same input impedance (the compression in the video might not make it clear how dramatic the difference is). It does seem to pick up a bit more noise, which I mention in the video. Before I soldered things up I did try one version of the fake ground lift (from the Bo Hansen box, with the small resistor, capacitor, and two diodes) on perfboard but my crude measurements didn't show much of a difference. Of course that was outside the box on the breadboard. I might go back in and put it between the XLR and circuitboard to get a better idea.

Not much to look at on the outside -- I'll give it a fun graphic once I think I'm satisfied with what's in the box.


https://www.dropbox.com/s/7ou1ptnnbyqwyh1/direct box guts.png?dl=0

 

[sr1200]

Jeff's DI is awesome (love it on bass).
CAPI-GEAR.COM (ZCON 11)

 

[merlin]

This popped up on my facebook. Thought I'd drop it here purely for interest.

 

[abbey road d enfer]

This popped up on my facebook. Thought I'd drop it here purely for interest.

I believe there is something very wrong with teh output section. Driving a transformer via a 47k resistor (R6) is not proper design.
Thi transformer is a 1+1:2+2. Even wiring it as a 4:1, the level loss is considerable as well as the LF degradation.

 

[midwayfair]

I believe there is something very wrong with teh output section. Driving a transformer via a 47k resistor (R6) is not proper design.
Thi transformer is a 1+1:2+2. Even wiring it as a 4:1, the level loss is considerable as well as the LF degradation.

Maybe it was a typo and it was supposed to be 47R?

 

[JohnRoberts]

Maybe it was a typo and it was supposed to be 47R?

Perhaps, mistakes are common in hand drawn schematics,

That schematic almost looks like a CAD drawing but even those are entered by humans.

JR

 

[abbey road d enfer]

Maybe it was a typo and it was supposed to be 47R?

Probably, but it's the kind of mistake that makes the difference between a more or less adequate circuit and a POS.

 

[JohnRoberts]

Probably, but it's the kind of mistake that makes the difference between a more or less adequate circuit and a POS.

Thus the value in understanding how a design works before copying it.

There are classic stories about rip-off copies copying mistakes too.

JR

 

[midwayfair]

There are classic stories about rip-off copies copying mistakes too.

Map makers used to include mistakes intentionally.

 

[JohnRoberts]

Map makers used to include mistakes intentionally.

or they said they did...

For today's TMI and I've told this story before, back last century when I was still working trade shows, on a slow last show day (sunday's were always slow), Greg Mackie wandered into the Peavey booth and struck up a conversation with me. He was mainly whining about Behringer ripping off his 8 bus... He chuckled that they copied his mistake too (I suspect he was talking about absence of a pad switch, but he didn't go into specific detail). We were far from friends but knew who each other was and shared a common enemy (the enemy of my enemy is my friend).

JR

 

[abbey road d enfer]

(the enemy of my enemy is my friend).

Which has been proved wrong so many times one wonders why politicians keep on doing the same mistake.

 

[JohnRoberts]

Which has been proved wrong so many times one wonders why politicians keep on doing the same mistake.

In world relations it is all relative. The three world powers constantly play a game of odd man out... Putin and Xi are not natural allies, just leveraging their common opposition for personal advancement.

JR

 

[analag]

Being bore and all that I made a tube DI about two years ago. I went a little extra on it as well. B+/- tube opamp style with BJT current source. I've been using NOS 5751 and 12AU7, but when I get motivated I'm going to roll 6N2p and 6N23p in it.

 

[Newmarket]

In world relations it is all relative. The three world powers constantly play a game of odd man out... Putin and Xi are not natural allies, just leveraging their common opposition for personal advancement.

JR

Quite a veer But I don't know Putin / Xi / Biden views on the preferred DI option.