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General => Open Discussion => Topic started by: jimilee on August 14, 2013, 03:32:49 PM

Title: Transformerless directbox
Post by: jimilee on August 14, 2013, 03:32:49 PM
 Been searching with some googlefoo, can anyone give me some advice or point me to a transformerless direct box?
Title: Re: Transformerless directbox
Post by: kothoma on August 14, 2013, 03:45:04 PM
Quote from: kothoma on August 09, 2013, 05:54:00 AM
Quote from: jimilee on August 09, 2013, 04:04:25 AM
Quote from: kothoma on August 03, 2013, 04:26:14 PM
Quote from: midwayfair on August 03, 2013, 03:20:34 PM
Quote from: jimilee on August 03, 2013, 01:17:13 PM
Quote from: kothoma on August 03, 2013, 07:24:13 AM
Curious as ever, what else will go into this multi pedal?
dude wants a tube screamer a chorus and a delay a headphone amp and a direct box. Not sure how much will actually fit though.

With all that active circuitry, what's the DI box for?

An active DI box (transformerless) to have XLR connectors and a balanced line to the mixing desk perhaps?
Transformerless D.I.? tell me more.

For example:
http://www.paul-gemine.co.uk/diboxes.html
http://sound.westhost.com/project35.htm
http://www.sonelec-musique.com/electronique_realisations_di_001.html
http://www.sonelec-musique.com/electronique_realisations_di_002.html
http://www.sonelec-musique.com/electronique_realisations_di_003.html

;)
Title: Re: Transformerless directbox
Post by: jimilee on August 14, 2013, 04:05:32 PM
Thanks, I knew that post was around here somewhere!  ;D
Title: Re: Transformerless directbox
Post by: raulduke on August 14, 2013, 04:44:27 PM
Another nice simple one for you here as well:

http://www.muzique.com/news/guitar-direct-box/ (http://www.muzique.com/news/guitar-direct-box/)

Also, Jack Orman (AMZ Muzique guy) sells PCB's for his DI box circuit.

He is a good guy, and somewhat of a DIY legend (creator of fabled Minibooster and Mosfetbooster circuits) so is worth supporting!
Title: Re: Transformerless directbox
Post by: kothoma on August 14, 2013, 04:48:44 PM
Quote from: raulduke on August 14, 2013, 04:44:27 PM
http://www.muzique.com/news/guitar-direct-box/ (http://www.muzique.com/news/guitar-direct-box/)

Neat. Probably can't be simpler. Thanks for this link!

Edit: BTW it's based on this: http://www.sg-acoustics.ch/analogue_audio/miscellaneous/pdf/OPA2134_DI-Box_r1.pdf
Title: Re: Transformerless directbox
Post by: Ettore_M on August 15, 2013, 12:05:15 AM
Hey, jimilee! I have done a single-sided layout for the H&K Red Box (Classic, I think). I don't remember well, but it's half SMD. I could easily make a thru-hole version of it, too. If you're interested, I could post it. But then again, it's not verified..

Hector
Title: Re: Transformerless directbox
Post by: jimilee on August 15, 2013, 12:31:33 AM
Quote from: Ettore_M on August 15, 2013, 12:05:15 AM
Hey, jimilee! I have done a single-sided layout for the H&K Red Box (Classic, I think). I don't remember well, but it's half SMD. I could easily make a thru-hole version of it, too. If you're interested, I could post it. But then again, it's not verified..

Hector
That sounds great, for a solder by numbers bassist, what is an H&K Red Box?
Title: Re: Transformerless directbox
Post by: RobA on August 15, 2013, 12:49:18 AM
Quote from: jimilee on August 15, 2013, 12:31:33 AM
... what is an H&K Red Box?
I'm guessing this guy http://www.hughes-and-kettner.com/products.php5?id=110 (http://www.hughes-and-kettner.com/products.php5?id=110)
Title: Re: Transformerless directbox
Post by: kothoma on August 15, 2013, 06:03:10 AM
Quote from: RobA on August 15, 2013, 12:49:18 AM
Quote from: jimilee on August 15, 2013, 12:31:33 AM
... what is an H&K Red Box?
I'm guessing this guy http://www.hughes-and-kettner.com/products.php5?id=110 (http://www.hughes-and-kettner.com/products.php5?id=110)
Yep, a speaker simulator and DI box. Tuned to 4x12" I think.
Title: Re: Transformerless directbox
Post by: Ettore_M on August 15, 2013, 08:10:01 AM
Quote from: kothoma on August 15, 2013, 06:03:10 AM
Quote from: RobA on August 15, 2013, 12:49:18 AM
Quote from: jimilee on August 15, 2013, 12:31:33 AM
... what is an H&K Red Box?
I'm guessing this guy http://www.hughes-and-kettner.com/products.php5?id=110 (http://www.hughes-and-kettner.com/products.php5?id=110)
Yep, a speaker simulator and DI box. Tuned to 4x12" I think.
Yes, indeed! I'm gonna be building this thing. I want to use it to record guitars direct from my amp, without using an attenuator or a microphone. Both are a little expensive for me, and I heard that this thing sounds really good!

Hector
Title: Re: Transformerless directbox
Post by: raulduke on August 15, 2013, 08:38:23 AM
The AMZ Op-Amp project PCB is also a nice option:

http://www.muzique.com/tech/opamp_multi.htm (http://www.muzique.com/tech/opamp_multi.htm)

I built a reamp and DI with these PCB's and they both work fine and sound great!
Title: Re: Transformerless directbox
Post by: kothoma on August 15, 2013, 08:53:30 AM
Quote from: Ettore_M on August 15, 2013, 08:10:01 AM
Quote from: kothoma on August 15, 2013, 06:03:10 AM
Quote from: RobA on August 15, 2013, 12:49:18 AM
Quote from: jimilee on August 15, 2013, 12:31:33 AM
... what is an H&K Red Box?
I'm guessing this guy http://www.hughes-and-kettner.com/products.php5?id=110 (http://www.hughes-and-kettner.com/products.php5?id=110)
Yep, a speaker simulator and DI box. Tuned to 4x12" I think.
Yes, indeed! I'm gonna be building this thing. I want to use it to record guitars direct from my amp, without using an attenuator or a microphone. Both are a little expensive for me, and I heard that this thing sounds really good!
Yes, forgot, it also takes speaker level signals.
Title: Re: Transformerless directbox
Post by: Ettore_M on August 15, 2013, 01:00:32 PM
Yes. It has Amp In, Line In, and balanced XLR output and Speaker Output. This way the signal is finally "attenuated" in the speaker itself, and you get your guitars recorded from the XLR without using a microphone.
When I'll build ths thing and verify it, I'll post a build report and a build document.

Hector
Title: Re: Transformerless directbox
Post by: kothoma on August 16, 2013, 07:28:24 AM
I've seen schematics of several versions of the Red Box.
But the speaker simulation always looks quite simple, a ROG Condor should be vastly superior.
What's nice is the input section with line in and speaker in/through.
Title: Re: Transformerless directbox
Post by: RobA on August 16, 2013, 10:39:49 AM
Personal preference here but if you are taking the signal into the digital world after the DI, then forget doing the speaker sim in analog and use a 5-band parametric EQ on the digital side. You can get much closer to actual speaker/cab frequency responses this way and it is far more flexible/easy to change between various different enclosure geometries, number of speakers, etc. Even if you are just going into a board with high and low shelf plus one or two parametric EQ's you can probably get a better cabinet sim than you'll get out of any of the analog versions of cabinet sims I've seen.


Title: Re: Transformerless directbox
Post by: kothoma on August 16, 2013, 10:47:56 AM
Right. You could even do convolution then...
But if you want to stay analogue or need a cab sim for a headamp then the Condor is a nice way.
Title: Re: Transformerless directbox
Post by: RobA on August 16, 2013, 11:00:40 AM
Quote from: kothoma on August 16, 2013, 10:47:56 AM
Right. You could even do convolution then...
But if you want to stay analogue or need a cab sim for a headamp then the Condor is a nice way.
Yep it does look nice. I've been meaning to build one for a bit. Actually, I've been thinking about stereo lately and doing a stereo Supro from ROG. I love the Supreaux Deux I built (I did delete the speaker sim section). Adding a stereo Condor cab sim could be really cool for running direct to a PA.
Title: Re: Transformerless directbox
Post by: kothoma on August 16, 2013, 11:37:21 AM
Quote from: RobA on August 16, 2013, 11:00:40 AM
Quote from: kothoma on August 16, 2013, 10:47:56 AM
Right. You could even do convolution then...
But if you want to stay analogue or need a cab sim for a headamp then the Condor is a nice way.
Yep it does look nice. I've been meaning to build one for a bit. Actually, I've been thinking about stereo lately and doing a stereo Supro from ROG. I love the Supreaux Deux I built (I did delete the speaker sim section). Adding a stereo Condor cab sim could be really cool for running direct to a PA.
Stereo, so you put some stereo fx in front?
Does the Supreaux Deux do clean/semi clean/light break-up or is it strictly distortion?
Title: Re: Transformerless directbox
Post by: Ettore_M on August 16, 2013, 12:15:20 PM
Quote from: RobA on August 16, 2013, 10:39:49 AM
Personal preference here but if you are taking the signal into the digital world after the DI, then forget doing the speaker sim in analog and use a 5-band parametric EQ on the digital side. You can get much closer to actual speaker/cab frequency responses this way and it is far more flexible/easy to change between various different enclosure geometries, number of speakers, etc. Even if you are just going into a board with high and low shelf plus one or two parametric EQ's you can probably get a better cabinet sim than you'll get out of any of the analog versions of cabinet sims I've seen.
Nice thought! I didn't think like that. This way, you could use your DAW's digital cab simulation (Amplitube, Guitar Rig). So you think it's better if I live out Red Box's cab sim or add an on/off switch for it??

Hector
Title: Re: Transformerless directbox
Post by: RobA on August 16, 2013, 12:52:24 PM
Quote from: kothoma on August 16, 2013, 11:37:21 AM
...
Stereo, so you put some stereo fx in front?
Does the Supreaux Deux do clean/semi clean/light break-up or is it strictly distortion?

Yeah, some stereo fx in front and some behind probably.

The Supreaux does some really nice clean to warm breakup. Like all the JFET based amp sims I've tried so far, it can easily get to some very silly levels of distortion, but the main reason I like it is the clean to warm side and then that it does respond well to having an OD whacked into it. It's not tubes, but it is good.
Title: Re: Transformerless directbox
Post by: RobA on August 16, 2013, 12:54:54 PM
Quote from: Ettore_M on August 16, 2013, 12:15:20 PM
... So you think it's better if I live out Red Box's cab sim or add an on/off switch for it??
Hector
If you can get it so you can switch it in and out, that would be the most versatile. It would be great to have the cap sim in some live situations where you don't want to do a digital interface and just want to be straight into the PA.
Title: Re: Transformerless directbox
Post by: kothoma on August 16, 2013, 01:15:40 PM
Quote from: RobA on August 16, 2013, 12:52:24 PM
Quote from: kothoma on August 16, 2013, 11:37:21 AM
Does the Supreaux Deux do clean/semi clean/light break-up or is it strictly distortion?

The Supreaux does some really nice clean to warm breakup. Like all the JFET based amp sims I've tried so far, it can easily get to some very silly levels of distortion, but the main reason I like it is the clean to warm side and then that it does respond well to having an OD whacked into it. It's not tubes, but it is good.

Yes, even a BSIAB2 has nice clean/low gain.
So this will probably be the next thing after building an Azabache... (and two dozen others).
Thanks for pointing this out!
Title: Re: Transformerless directbox
Post by: Ettore_M on August 16, 2013, 02:06:34 PM
Quote from: RobA on August 16, 2013, 12:54:54 PM
If you can get it so you can switch it in and out, that would be the most versatile. It would be great to have the cap sim in some live situations where you don't want to do a digital interface and just want to be straight into the PA.
Thanks a lot for this! It's something I haven't thought about. I'll try to add a switch to the cab sim. I just don't know which part of the circuit it is. I'll read some in the ROG, and maybe add a Condor as the cab sim. That would be versatile.

Hector
Title: Re: Transformerless directbox
Post by: kothoma on August 16, 2013, 02:12:32 PM
Quote from: Ettore_M on August 16, 2013, 02:06:34 PM
Quote from: RobA on August 16, 2013, 12:54:54 PM
If you can get it so you can switch it in and out, that would be the most versatile. It would be great to have the cap sim in some live situations where you don't want to do a digital interface and just want to be straight into the PA.
Thanks a lot for this! It's something I haven't thought about. I'll try to add a switch to the cab sim. I just don't know which part of the circuit it is. I'll read some in the ROG, and maybe add a Condor as the cab sim. That would be versatile.
What version/schematic of the Red Box are you using? I remember one with two Sallen-Key lowpass filters as a cab sim.
Title: Re: Transformerless directbox
Post by: kothoma on August 16, 2013, 04:36:46 PM
Quote from: RobA on August 16, 2013, 12:52:24 PM
Quote from: kothoma on August 16, 2013, 11:37:21 AM
...
Stereo, so you put some stereo fx in front?

Yeah, some stereo fx in front and some behind probably.

So you'd use dual pots?
Title: Re: Transformerless directbox
Post by: RobA on August 16, 2013, 04:44:28 PM
Quote from: kothoma on August 16, 2013, 04:36:46 PM
...
So you'd use dual pots?
That's a good question. At first I thought I would, now I think probably not. I think I'd like the flexibility that would come from having individual channel control.
Title: Re: Transformerless directbox
Post by: noobtoob on August 16, 2013, 10:32:31 PM
Hey guys, new to the forum (well... new-ish. I'm kinda lurking/learning), this thread is right up my alley and I hope I get to build a DI when I get funds! I've been looking for something I may have seen a build of, anybody have links for an amp/cab emulator or, maybe, what tone-shaping considerations I should make designing my own? I know enough to (with Google) get myself through a project stem to stern, so I was hoping to design at least the schematic.
Title: Re: Transformerless directbox
Post by: Ettore_M on August 17, 2013, 09:23:04 AM
Quote from: kothoma on August 16, 2013, 02:12:32 PM
What version/schematic of the Red Box are you using? I remember one with two Sallen-Key lowpass filters as a cab sim.
I use the Classic version. Yes, it has indeed two Sallen key low-pass filters. Now I wonder what I could do in the circuit. The only way is to use a switch to switch between using the two filters or "jumping" them to the final stage.

Hector
Title: Re: Transformerless directbox
Post by: kothoma on August 17, 2013, 09:34:26 AM
Quote from: Ettore_M on August 17, 2013, 09:23:04 AM
Quote from: kothoma on August 16, 2013, 02:12:32 PM
What version/schematic of the Red Box are you using? I remember one with two Sallen-Key lowpass filters as a cab sim.
I use the Classic version. Yes, it has indeed two Sallen key low-pass filters. Now I wonder what I could do in the circuit. The only way is to use a switch to switch between using the two filters or "jumping" them to the final stage.
Most signific difference between
http://elektrotanya.com/PREVIEWS/63463243/23432455/hughes-kettner/hughes-kettner_red_box_classic_sch.pdf_1.png
and
http://analogguru.an.ohost.de/193/schematics/H&K_RedBox-MkII.gif
is that little extra passive filter between the input stage and the first LP stage.
To put in a Condor you would only use the input stage and inverter stage for the "cold"/(-) output of the XLR.
Edit: You would probably skip the input stage of the Condor then.
Title: Re: Transformerless directbox
Post by: Ettore_M on August 17, 2013, 11:20:39 AM
I'll probably just add the switch to overpass the filters, as RobA suggested, and not the Condor, as it will result in a complicated build. I'll post results and build reports when I get to build it!
Thanks!

Hector
Title: Re: Transformerless directbox
Post by: jimilee on August 17, 2013, 03:06:51 PM
Quote from: Ettore_M on August 17, 2013, 11:20:39 AM
I'll probably just add the switch to overpass the filters, as RobA suggested, and not the Condor, as it will result in a complicated build. I'll post results and build reports when I get to build it!
Thanks!

Hector
anxiously awaiting your results!
Title: Re: Transformerless directbox
Post by: Ettore_M on August 17, 2013, 08:03:22 PM
Quote from: jimilee on August 17, 2013, 03:06:51 PM
Quote from: Ettore_M on August 17, 2013, 11:20:39 AM
I'll probably just add the switch to overpass the filters, as RobA suggested, and not the Condor, as it will result in a complicated build. I'll post results and build reports when I get to build it!
Thanks!

Hector
anxiously awaiting your results!
Me too! I have a lot of my projects waiting to be verified (this one, SMD MXR Dist+, SMD Really Cheap Compressor, my "Wicked Switch", for which I also made a double-sided layout to be fabbed, and the list goes on..). But I hope this will be the first to build, 'cause I need it for some recordings. Hopefully, I'll finish it late September.

Hector
Title: Re: Transformerless directbox
Post by: jimilee on September 07, 2013, 08:02:22 PM
Quote from: raulduke on August 14, 2013, 04:44:27 PM
Another nice simple one for you here as well:

http://www.muzique.com/news/guitar-direct-box/ (http://www.muzique.com/news/guitar-direct-box/)

Also, Jack Orman (AMZ Muzique guy) sells PCB's for his DI box circuit.

He is a good guy, and somewhat of a DIY legend (creator of fabled Minibooster and Mosfetbooster circuits) so is worth supporting!
So I'm going with the AMZ direct box and a jmk pcb for the headphone amp. In a multi effect box, can I come off of the last effect and into a dpdt on/on switch and have that toggle between the headphone amp and the transformerless direct box and both of those be wired to the output jack? I don't know how I get myself into these things, but a friend asked me to build this monstrosity for him. 4 effects, a headphone amp and a direct box.
Title: Re: Transformerless directbox
Post by: kothoma on September 08, 2013, 05:37:59 AM
Quote from: jimilee on September 07, 2013, 08:02:22 PM
In a multi effect box, can I come off of the last effect and into a dpdt on/on switch and have that toggle between the headphone amp and the transformerless direct box and both of those be wired to the output jack?

How many output jack would there be?
- (asymmetric) regular pedal out (before DI box and phone amp)
- (stereo?) phones
- symmetric DI out: 1 TRS and 1 XLR, or only one?

No need for a switch then. Or are any of these outputs to be combined? Are you sure he doesn't want DI and phones at the same time (for direct monitoring perhaps)?
Title: Re: Transformerless directbox
Post by: kothoma on September 08, 2013, 05:44:34 AM
And you surely had a look at http://www.madbeanpedals.com/forum/index.php?topic=10123.0 already?
It provides cab sim, headphone amp (stereo) and DI out.
Title: Re: Transformerless directbox
Post by: jimilee on September 21, 2013, 01:18:16 AM
Quote from: kothoma on September 08, 2013, 05:37:59 AM
Quote from: jimilee on September 07, 2013, 08:02:22 PM
In a multi effect box, can I come off of the last effect and into a dpdt on/on switch and have that toggle between the headphone amp and the transformerless direct box and both of those be wired to the output jack?

How many output jack would there be?
- (asymmetric) regular pedal out (before DI box and phone amp)
- (stereo?) phones
- symmetric DI out: 1 TRS and 1 XLR, or only one?

No need for a switch then. Or are any of these outputs to be combined? Are you sure he doesn't want DI and phones at the same time (for direct monitoring perhaps)?
This looks like what my goal is, 3 outs. DI will be XLR, regular pedal out and head phone out.
Title: Re: Transformerless directbox
Post by: jimilee on September 24, 2013, 03:27:23 AM
Bump for the dumb guy. Would I need a buffer / splitter  off the last effect?