Topic: New TS-2 Preamp ... under development (part II)

[anechoic]

I cast my vote for 100Hz -12dB/oct slope
good for wind and low freq rumble

[stevetoney]

One extra switch available?  I think it'd be totally cool if you could have a switch to choose to run the preamp with the transformer inputs sometimes and run the preamp with no transformers and capacitor coupling the other times -- make it like two distinct preamp flavors in one!

Todd...you can do that and still have a functional preamp??  I thought the same thing last night when I was dreaming about uses of the extra switch, but didn't think it was a credible suggestion...not because of any reason just because I didn't know it could be done.  Again, I know nothing about design.  If that's a possibility, I think that would also be a very cool option.

[digifish_music]

You guys are gonna kill poor fivefish with feature creep 

Better feature creep than creepy features

Good question tho, what is the current target spec?

1. Inputs: 2X XLR, Power Jack.
2. Outputs: 2X XLR
3. 2 channels.
4. Gain: ~60 dB?
5. 5 segment LED peak-meter

Switches:

4. P48V (independent channels) ON/OFF.
5. LED peak meters, ON/OFF
6. Low cut filter (both channels) ON/OFF.
7. -20 dB Pad (both channels), ON/OFF

Power:

8. Input 4.5~14V DC
9. External power supply only?

[sanaka]

Gain: ~60 dB?

From 5Fish website, spec on SC-1 preamp, on which the TS-2 is based:

- Gain range from +6 to +72dB, in 6dB increments

So, pretty sure the gain is more like ~70dB. Which for me is one of the big draws. Majoro gain and low noise. This and the high freq. response is what makes this really good for the nature/bat chirp recording crowd too.

Peace,
Sanaka

[anodyne33]

5F, I've not read all of the reviews of your existing pre kit, but I have hears some of the samples that you posted and thought the sound decent. It's difficult to tell from samples on my computer speakers what your pre 'sounds' like though.

I guess my question is, if you had to compare your circuit with some other well known pre-amps out there, what do you think matches it most closely in terms of 'flavor' (timbre, tonality, etc)?

The main reason I ask is that the most beautiful thing I think I've ever heard was a 57 on a nice snare through an API 3124, and I've always wanted to hear what something like that would do in a ambient recording situation, but I'm sorely lacking the funds to own APIs, and the motivation to devise a scheme to power them in the field.

[fivefishdiy]

I guess my question is, if you had to compare your circuit with some other well known pre-amps out there, what do you think matches it most closely in terms of 'flavor' (timbre, tonality, etc)?

My "stock version" (i.e. without the transformers) I would think is similar to the "API Arsenal Audio" R20 and the DAV BG1.

I don't own either so I have not personally heard them... just what people tell me.
Some people that owned both SC1 and DAV have said my pre sounds cleaner and clearer than the DAV.

The R20 just came on the market last week? I read on the API R20 preamp manual that it uses the same mic pre chip and balanced driver chip as I'm using. So I would think it will sound the same too, not unless they did some other things to it also.


The main reason I ask is that the most beautiful thing I think I've ever heard was a 57 on a nice snare through an API 3124

The "transformer version" I have is using the same input transformers commonly used with API clones.

The character of my pre with and without the input transformer is different. It's a bit more "thicker" with the input trannie.


8. Input 4.5~14V DC
My goal was to design this with 12VDC input.  But through testing, I found out I still get signal even with 4.5VDC input.  My FET mic isn't happy though with the powered by 4.5VDC input. The Phantom power's voltage isn't high enough for my FET mic to work.  But bumping the input to 5.0VDC input, and my voltage hungry FET mic worked. For other types of condenser mics, it worked with the 4.5VDC input.

But if you can, I recommend 12VDC input.

Note: Your max dBu output will be reduced when running on reduced voltage input than 12V. i.e. lower headroom. But then again, you probably don't need +23dBu output whipping the inputs of your AD converter.


9. External power supply only?
External battery, wall wart, via DC jack.
No Internal batteries.

[kirk97132]

I hope the number of +Ts I have = the number of sales I'll have    (okay, I'm dreaming)

I can see your pre dominating the tapers section in just a few years

[fivefishdiy]

Wasn't there also an issue with the voltage supplied vs. voltage indicated by your external battery? That is, supply current barely changed as selected battery output voltage changed by a factor of three?  Which raises the issue of the accuracy of the battery's voltage indicator.  It could be worthwhile to measure the true output voltage of the battery under load at different settings, otherwise that could result in inaccurate performance measurements at varying supply voltages.

I don't think so.  Here's the indicated vs. actual voltage measured. (Yes, this is loaded with my pre, and both the split PSU and 48V converter section running.)

4.5 = 4.58V
5 = 5.09V
6 = 6.12V
7.5 = 7.67V
9 = 9.24V
12 = 12.22V
14 = 14.21V

Though I agree that the constant current consumption at even the different voltages is a mystery. Normally, current consumption should be higher at the lower voltages.

YMMV with other batteries. I just tested this with a Tek battery.


There are only two types of condenser mics, FET and tube

By "FET" mics, I'm referring to my Sterling/GrooveTubes FET LDC mics (labeled as such on the mic body). 

Tube mics will have their own PSU and don't need PP from the pre.

[trustthex]

I've read this entire thread in the last 2 days... i've been a prodigal taper lately (damn you work), but am looking to upgrade to an open rig...  everything about your pre that i see, i like...  I would be running it into an r-09 at first, as alot of us do, and it only has 1/8 for inputs, alot of recorders out there do...  If it wouldn't be too much to ask, plz add either rca's or a 1/8 output to it so the rest of us folk can easily run them into our recorders as well.  I realize I could go xlr>1/8,  but having the extra output would also benefit patchers (people who hook their recorders into someone else's mics>pre).

[rePat]

Checking in for Round Deux.

[anechoic]

9. External power supply only?
External battery, wall wart, via DC jack.
No Internal batteries.

>>this might be an obstacle for field recordists who carry their gear rather than keep it next to a mic stand/tripod setup
?

[fivefishdiy]

Sorry, I can't put a battery inside. (Note, I'm not using a custom-made case where I can have every feature/opening/design/dimension made to spec to my liking. Maybe when I become big like "Grace" or "Sound Devices"  

There are portable batteries you can use though.

[anechoic]

true and they have become a lot less bulky than they used to be
so maybe not a show-stopper for the PortaBrace crowd

[stevetoney]

9. External power supply only?
External battery, wall wart, via DC jack.
No Internal batteries.

>>this might be an obstacle for field recordists who carry their gear rather than keep it next to a mic stand/tripod setup
?

This really isn't that much of an issue, even for birders, IMHO.  It becomes a pretty big PITA to open it up and replace 9V batteries all the time, which isn't cheap either since it would generally take three nine volts to last the 4 hours or more expected.  That's at least $6 a pop for power.  Using one of these rechargeable tekkeons or the infamous wally world's is so simple.  And chances are pretty good a preamp's not going anywhere anyway without a bag of some kind to also carry the mics, cables, accessories.  So, the bag will hold the battery...or what alot of people do is put a velcro strip on the battery and the bottom of the preamp to enable the two to be pseudo attached. 

[fivefishdiy]

Ch-Check it out!  We're going places. 

My SC-1 preamp has been mentioned again in MIX Magazine. Wohoo!

Note: The TS-2 preamp is based upon my SC-1 preamp design.... just a different form factor (stereo) and options for input transformers.

AUGUST 2008 issue

Field Test: Avant Electronics Avantone CK-40 Stereo Mic
http://mixonline.com/gear/reviews/audio_avant_electronics_avantone/

and also back in MAY 2008 issue

Field Test: Peluso 22 47SE Tube Microphone
http://mixonline.com/gear/reviews/audio_peluso_se_tube/


BTW, check out the review of the CK-40 stereo mic. This could be a good mic for tapers.