Rochey

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #20 on: November 15, 2012, 03:59:48 PM »
Just a thought - dc blocking caps are only neede when phantom is present, right?

Providing the cap was switched in first, or switched out last, it might be possible to set a system that bypasses the dc blocking cap whenever phantom is not applied.

The only danger would be if an external dc source is being used.

Cheers

/R
Expat Audio Home: http://www.expataudio.com


Rochey

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #21 on: November 17, 2012, 12:00:33 AM »
I was asked for a video of the pnp machine.
Here goes!

http://www.youtube.com/watch?v=5jD3Gg8T0bI&feature=youtube_gdata_player

This is actually assembling an early proto.

/R
Expat Audio Home: http://www.expataudio.com

Dylan W

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #22 on: November 17, 2012, 12:48:38 AM »
I was asked for a video of the pnp machine.
Here goes!

http://www.youtube.com/watch?v=5jD3Gg8T0bI&feature=youtube_gdata_player

This is actually assembling an early proto.

/R

Never seen one of these things before- cool!

Are there still any plans to offer a DIY version?

Dylan

Rochey

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #23 on: November 17, 2012, 11:20:10 AM »
Dylan, it is the diy version. Hook up pwer, input and output, the options to diy are:

Mechanical. (what case?)
Front end switching (relays? Switches? Ribbon mic input?)
VU metering (use the unbalanced output if you like)
Power (mains powered using a uberpsu or battery powered from 2x 9v?)

Regarding "solder yourself" smd projects, we may put some small adaptor boards for people to dabble with, but at this point, i'm trying to pay off the assembly machine - so its getting as much use as possible.

Dont forget that the board comes fully tested as well. Thats always a big help with diy projects!

:)
Expat Audio Home: http://www.expataudio.com

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #24 on: December 04, 2012, 07:12:20 AM »
Hi Rochey, I did not know how to contact you guys at Expat Audio, so I pm'd you about the Eden preamp... looking for further info on how it sounds...

mulletchuck

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #25 on: December 06, 2012, 12:54:58 AM »
post some clips of how it sounds!
www.youtube.com/mulletchuck for all my recordings

Rochey

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #26 on: December 06, 2012, 01:17:38 AM »
I'm working on it!

It's kinda hard.... Its response is so flat that i fear it'll sound like i'm playing games with normalizing the audio in a wave editor!

The best i can do to keep it honest is do a dac to adc path, one direct without te Eden, then one with an attenuated output, being gained up by an eden board.

But again, given the flat response, i suspect that it will just sound like its been normalized.

Stay tuned! I have another member buying a 4 set this week that will soe testing with an acoustic swing band. That sounds like a *perfect* test!
Expat Audio Home: http://www.expataudio.com

mulletchuck

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #27 on: December 06, 2012, 03:57:21 AM »
lol OR you could just hook up a mic, and get someone to play some guitar/drums/whatever while you record it into your daw with a decent converter (no mBox's please)
www.youtube.com/mulletchuck for all my recordings

Kingston

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #28 on: December 06, 2012, 05:17:09 AM »
There seems to be a strange misconception here that one could actually hear THD+N of 0.003% with any sound reproduction instrument.

Most of that 0.003% is probably from the conversion stages and not the preamp itself anyway.

Rochey

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #29 on: December 10, 2012, 03:44:37 PM »
First of all, Thank you Angelo for your order! I'm looking forward to some samples to share with other folks here in the new year!

Secondly, Angelo was kind enough to allow me to copy/paste some of the discussion we've had via PM. He asked a lot of good questions (I'm not sure if my answers were good enough, but it may be of some benefit to folks!).

Quote
... I'd like to know, what source would you use it with: You say it's very clean sounding, but I'm not sure how and when this could be a good thing (I am more used to "colored" stuff, such as API...). I need to know if these boards could actually be what I'm looking for.

Everyone has opinions on what sounds good. I like Clean Pre's because I can then color the sound after I've recorded it. I can add EQ, Compression and other effects, or even run the signal into another pre later on. Clean Pre's give me options AFTER the artist has left! . The whole concept behind the Eden Pre was to get "Wire with Gain". The plots in the users guide show flat distortion by frequency, along with very low distortion levels even at high gains.

Keiths' (SSLTech - Mr Analog at Expat Audio) first thoughts for material to record with this pre is anything Acoustic, Orchestral or Choral. Anything where you want to capture much more detail, and add much more gain is where Eden will excel. Think of recording an acoustic guitar, where you want to capture the room, as well as the detail in the guitar players technique. Eden is going to do it fabulously.

Keith is building a 4-pack of Eden's into a 1U case. He will be recording a choir in Florida with it soon. Those samples will be available in the next few weeks I hope.

Quote
But I have a question about your front switches: I saw they are digitally controlled, would this somehow affect the analog audio path? ...just to be sure I won't have any digital glitches or pops
The digital section can run from its own supply if you like. It never touches the analog. All it does is switch relays. I used a separate 12v power supply (from a dollar store!) and put it inside the case.

Quote
would your Uber PSU supply enough power for 4 Edens?
As for the drive capability of the uber supply. 4x Edens will be easy.
The ina163's each require 10mA, The drv135's require 5mA each. led's are are a total of 15mA and the opa134 is another 5mA... Giving a total of 45mA.

Quote
just to be sure, when you say "I used a 12v power block" you mean I'll need extra 12v to feed the switches? - or you just mean that those 12v for the relays come from the digital supply?  sorry, I did not understood this passage 
You'll need OMRON G6K-2P-XXX relays for the front end switching. They come in a variety of voltages.
On mine, I used G6K-2P-DC12. They require 12V on them to switch.
The Digital Control Board uses a regulator to take any voltage above 3.3V (up to about 24V?) down to 3.3V. That 3V3 is used to power the micro controller and the LED's for the switches.
The Digitally Controll Mic Pre Front-End has transistors on it that take the 3V3 from the microcontroller board, and switch the 12V to the relays.

Alternatively, you could use 5V relays (G6K-2P-DC5). That would allow you to use a small 5V supply for the digital section.
That would be VERY nice. Then you could use a small cell phone charger (think how small an Iphone charger is!).

You could put a small cell phone charger inside your rack case, that will be shared with the primaries of your toroidal transformer. (same ground).
The DC5 relays require 21mA to activate. you have 12 of them in a rack. Thats ~250mA. That's about half of what a low cost 5V cell phone charger can supply.

So --- In Summary. I suggest either a 5V or 12V power supply to supply the digital switching boards and relays. The selection is based on which G6K-2P Relays you select.

Thanks again Angelo - Really appreciate the feedback, the questions and your order!
Expat Audio Home: http://www.expataudio.com


pasi_k

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #30 on: December 13, 2012, 10:24:27 AM »
Regarding to Uber:

ArenĀ“t the 78/79xx - series regulators little suspicious for audio quality?
How come you wouldnt do all the regulations with LM317/337

Pasi

Rochey

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #31 on: December 13, 2012, 04:28:07 PM »
pasi - great question.
I asked Keith to comment (he selected those regulators)
Quote
I0've had a lot of noise issues with 317's, which adds to the circuit complexity by the time they're addressed. -The 317-based 48V supply rail for example is more complicated than the 78/79 based rails.

I'd also add that a lot of the high frequency noise is already filtered away, making the HF rejection work required by the 78xx much easier.

Expat Audio Home: http://www.expataudio.com

zebra50

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #32 on: December 26, 2012, 05:00:17 PM »
Hi Rochey,

These look really nice - I'm going to have a crack at a pair or quad for my ribbon mics, so look out for an order.

A quick question - the fixed 12 ohm gain resistor gives maximum gain of 54. Is there any problem removing/bypassing this, and using a rotary switch to vary the gain up to 66dB as per the data sheet?

Hope you had a great Christmas

Stewart
Ribbon microphone services
http://www.xaudia.com
Microphone blog

Rochey

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #33 on: December 26, 2012, 05:13:09 PM »
Stewart,

I'm thrilled to hear about the incoming order! ;)

It's set to 54dB on the ina163, but the DRV line driver gives another 6dB of gain.

originally, we had a 6Ohm resistor (if memory serves). Our initial tests showed that at high gain (near 70dB) the device starts to distort a little more.
Your mileage may vary.

/R
Expat Audio Home: http://www.expataudio.com

zebra50

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #34 on: December 26, 2012, 05:20:02 PM »
Well, I'll check it out and post the results back here. 70 dB is bordering on the insane even for ribbons, but perhaps 60dB from the INA163 plus 6 would be good to have. I may try that on one and see how it goes.

I've ordered a quad - the four-for-three pricing was too good to pass on - plus your power supply board. I haven't gone for the front end plus controller as I was planning on a box with just 4 gain knobs, and that's it! Dead simple.

Will let you know how it goes.

Stewart
Ribbon microphone services
http://www.xaudia.com
Microphone blog

mulletchuck

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #35 on: December 26, 2012, 06:29:03 PM »
So what do they sound like??   I can't believe that you've built a bunch of these and haven't recorded any music with them :P   ::)  ;D
www.youtube.com/mulletchuck for all my recordings

Rochey

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #36 on: December 26, 2012, 06:34:52 PM »
I have some samples incoming in January.
Expat Audio Home: http://www.expataudio.com

mulletchuck

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #37 on: December 26, 2012, 07:49:20 PM »
 :-\

it can't be that hard to hook up a mic, and connect it to your interface and press 'record' in Garage Band or Windows Media Recorder, can it?!?!
www.youtube.com/mulletchuck for all my recordings

Rochey

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #38 on: December 26, 2012, 08:19:01 PM »
What you'll hear is my crappy mic and a square room that has no treatment!

Keith should have recordings for me in January, once he finishes a big studio install.

Till then, i'll see (as discussed previously) about doing a dac-to-adc and a dac-eden-adc comparison. Thats the fairest way i can do a comparison.

/R

Expat Audio Home: http://www.expataudio.com

mulletchuck

Re: Expat Audio EDEN Microphone Preamplifier
« Reply #39 on: December 26, 2012, 08:45:20 PM »
well, you could always send a demo unit up here in NYC and hear it on a CV4 via a Symphony I/O :-D    :P  ;D
www.youtube.com/mulletchuck for all my recordings


 

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