Topic: Greetings... my new mic preamp.

[fivefishdiy]

jerryfreak

The metalwork is a big ? at the moment. I'm still deciding how the aluminum front panel should be finished.

So the answer to your question.... no definite price yet.

But rest assure I want this thing to sell... so I will surely price this reasonably and competitively.


O-Canis

There is nothing inside the aluminum case that generates a lot of heat so heat is not going to be a problem. It's not even going to get warm.

Heck, even the 110V/220V-powered rack preamps I make barely just get warm. So I'm not worried about heat problems on a 12VDC powered preamp.

[sanaka]

+T Five Fish Man!!   

I've been waithing to get my 50 posts in so I could +T you on this thread!

I remember talking to you about this on your own forum. I'm so glad things are progressing here for the Tapers. I think your pre is going to be Da Bizness.

Maintaining the high gain with low noise, super clean performance in the portable version makes your TS-2 not only super versatile and flat out awesome, but also fit squarely into the nature recordists' niche.

I bow to your design sensibilities, Dude.



Peace,
Sanaka

[GDfan]

FiveFishdiy,
Do you have any idea when these will be available? 
Are you still a couple months away from having a finished product for sale?
It looks near complete, but I am no expert.

[fivefishdiy]

Sanaka
Yeah, finally getting there... slowly.


GDfan : Are you still a couple months away from having a finished product for sale?
It looks near complete, but I am no expert.

That's a good guesstimate. Maybe even 3 mos.

There's no case work yet, the VU meter needs to be redone, and I usually build 2-3 prototypes to make sure it works.... EVERYTIME it's built.   Also, haven't had a chance to totally burn-in the unit to see that no problems comes up.

[Todd R]

Fivefish --

Now that the boards are in and the preamp is coming together, could you refresh our memories on what the features will be?  I tried reading through the thread, but I'm not sure I found everything. 

IIRC, it was something like 6db stepped gain, trim pot adjustment between the gain steps, separate 48v phantom selectable for each channel, phase reversal for each channel (mainly for the home recording types).  Did you decide on having a high pass filter option?  Battery requirements -- 9v or 12v, will 7.2v cells work?

This still looks very cool, great to see the progress!!

[fivefishdiy]

could you refresh our memories on what the features will be?
6db stepped gain
Yes.

trim pot adjustment between the gain steps,
Yes.

separate 48v phantom selectable for each channel,
Yes.

phase reversal for each channel (mainly for the home recording types).
Yes... POLARITY reverse.

Did you decide on having a high pass filter option?
No filtering.  Mixed response here from tapers.

 Battery requirements -- 9v or 12v, will 7.2v cells work?

Yes, Yes, Yes.

While the pre will still work down to 6.5Volts, I recommend 9-12VDC input. Max 14V.

Sidebar: I have the Tekkeon battery with the adjustable outputs. I remember that the pre worked on any setting between 4.5V to 14V.  But I didn't test it with condenser mics. I should try that.



 

[Phiegze]

Re: highpass
Since some wanted it could be switched out of the path was it eliminated just to save space?

[fivefishdiy]

There were also other issues associated with it.  Additional opamps, increased power consumption, cost, and the switches are on a separate board and I dont want LOW level signals jumping back and forth between the motherboard and switchboard.

If you want the signal filtered, it can be filtered during post processing, and you'd have better control of cutoff frequencies, Q factor, dB reduction, etc... during post.  If the filtering is in the box, it's fixed and you cannot UNDO undo it later.

[fivefishdiy]

Tested the other channel on the preamp board... oh yeah... it works!

Now, time to do some burn-in testing.

BATTERY TESTING Part Deux...
Hooked up the 2-ch pre to a Tekkeon battery... run some music signal and listened to it on my monitors... everything connected using test clips. What's the current consumption of the preamp? (i.e. with the VU Meters turned off)

* You can see which LED is lit up on the Tekkeon battery which designates the output voltage selected.

TESTING AT 12VDC ... of course no surprise here, it will work


MAX voltage input is 14VDC...


Okay, no surprises there...

Just for kicks... I decided to lower the input voltage to see how it holds up... At what point will the sound disappear and the pre stops working?

Let's try 9Volts... still works.



How about 6Volts... surely it will drop at 6Volts... but nope, it's still working.


This is disappointing...  Let's try 4.5Volts input... That should kill it!

Nope... still working...

Okay, the lowest setting on the Tekkeon battery is 3 Volts... let's kill this pre, die die die.


Unfortunately, it's still working. Sound is still coming out of the pre. I've been listening for the past half-hour with the pre running on 3Volts from the battery and no problemo. It's still going. 

Nothing feels hot. Not the battery, not the preamp, not the various chips, not the PSU section. Everything is C.o.o.l!

Sooooo, you can say I'm pretty pleased about the results.

PS: Notice my new multimeter? Yep... It's a Fluke, baby   

PPS: I'm not recommeding running it at a too low voltage like 3Volts, because that will affect your headroom (lowers your available headroom... most obvious when you have a thumping bass or low frequencies in your signal.)  4.5Volts is still good though

[intpseeker]

This is way cool! +T, of course.

How do you explain for the EE challenged the low voltage needed to run it?

[fivefishdiy]

Current draw on the battery must increase as voltage supply decreases, no?

Normally yes, current should increase as voltage decreases. That's the normal behavior I had with the 9V Duracell testing.

What part of your circuit are you measuring current? After the DC converter, I presume?
No, The figures shown above is the current draw from the DC supply (i.e. from the battery, before the DC converter).

I am surprised by the current readings too... the only thing I can think of is the Tekkeon battery has internal electronics in it (an adjustable boost converter?), and is not a straight battery. 



Oops, forgot to answer this one.

How do you explain for the EE challenged the low voltage needed to run it?

The answers are the chips I'm using run on a wide range of voltages. Then using a DC converter, it's possible to "step-up" the input voltage from something low to a higher voltage... sufficient to operate the chips.

[rsimms3]

I haven't posted here, but I have been watching.  Awesome to see something go from concept to reality.  Your battery test, is that with full 48v load on it?  I only see 1 XLR connected in the top left.

[fivefishdiy]

No, I don't have the switchboard connected yet to the motherboard in the above tests.
(The 48V supply is on the switchboard PCB.)  I'll do another battery test with the whole shebang running.

But on an earlier test, these are the numbers I got, 2 channels loaded with FET condenser mics and 48V phantom.
2 Channels, with +48V phantom power, loaded with mics, plus VU Meters = 170mA - 190mA  
The current consumption varies... depends on how many LEDs were lit up in the VU meters.

[jerryfreak]

100-200 mA at 6V? you gotta be kidding me.

Bravo!

when you gonna add an a>d stage?

[fivefishdiy]

Nothing much happening... awaiting some cable assemblies that I'd like to use with the TS-2 prototype. It should be here tomorrow.

Meanwhile, I found out a customer of mine from Netherlands made this recording. With his permission, it's posted on my website. The setup is just a pair of Oktava mk012 cardiod Microphones in a (10 x 18ft) room and 2-channels SC-1 Preamp recorded into a Yamaha AW1600.

It's a simple live recording setup and I thought you guys may be interested to hear it since it's similar to a tapers setup.

Full credits here:
http://fivefishstudios.com/index.php?option=com_content&task=view&id=17&Itemid=48

Audio file:
http://www.fivefishstudios.com/audio/without_Jean.mp3

The TS-2 preamp is based on this same SC-1 preamp, but with the addition of input transformers and an additional buffer stage.  This should give you a close idea of how the TS-2 sounds and I think the TS-2 will sound even better due to the input trafos. (Other sample SC-1 recordings can be heard on the above webpage too.)