Topic: Greetings... my new mic preamp.

[fivefishdiy]

Finished the PCB for the switchboard/48V supply.  I can already see 3 changes I need to make. Mechanical dimensions and exact placement of switches, holes not yet finalized.

I just need a few more days to mull this over, review it, criticize it, edit, change until I'm satisfied, then off to prototyping. It costs a few hundred dollars per prototype run. And no matter how much I reviewed each revision, it takes me about 3-4 prototypes to get it to where it's really finished and ready for production.

The preamp also has soft-start 48V, meaning the 48V is raised gradually to avoid the THUMP when turning on or off phantom power. It also protects your expensive mic from a sudden 48V surge. And if you accidentally turned PP on, you can turn it off immediately and your mic wouldn't get the full 48V across it.

O-Canis
Those switches are kinda expensive. So trying not to go there. My switch will have a solid feel to it. Not wimpy. LED lights are separate from the switch.

Gutbucket and nashphil
I actually prefer all XLRs on one side too, i.e. the back.  I probably misunderstand this thread. I thought the consensus and preferred way was XLRs on the sides?

Either way, I think it will be possible to offer it with XLRs on the sides, or the back.  XLRs on the sides will just cost a little bit more (because of the additional manual labor).

I like the stereo-mini output idea.

This may be doable.  The rear panel okay? If I can find space on the front panel, it will go on the front panel.

Re: Mini-XLRs
Again, can be offered as an option.  Since the XLR jacks will be connected to the PCB via flying leads, we can have any jack format you want. TRS if you want, or mini-XLR or full-size XLR.


nashphil

offered to let me try out one of this 4 ch transformerless designs in a few weeks.

Sorry, I still don't know where my 2 (4)-channel rack units are. They're floating somewhere in Nashville. So you'll probably get the 1-ch pre to play with.


campbrs
1. See answer above.
2. The options are: No transformers, with Cinemag, with Jensen, with Lundahl (maybe).. Also with XLRs on the side or back, or mini-XLR if you want.  Each option will be priced differently.
3. The balanced output of the pre can be used with unbalanced inputs. Just use pin 2 and 3. My balanced driver "behaves" like a transformer, even though it's solid state.
4. Kit? We'll see how easy or hard it is to build. Otherwise, I may spend a whole lot of time handholding kit builders. 
5. The pre will still operate down to 6.5Volts during my testing. But ideally, 12V is preferred though 9V will also work (down to 6.5V). See a previous post of mine... 9V Battery Duracell testing a few pages back.

[rowjimmy]

4. Kit? We'll see how easy or hard it is to build. Otherwise, I may spend a whole lot of time handholding kit builders. 

One thing about introducing this as a kit to this community, you'd see a lot of self-sufficiency amongst the group. A couple threads would pop up for people to discuss questions, problems, etc. and those with greater skills would probably be quite a bit of help to those who may
find themselves in over their heads.

[Roving Sign]

4. Kit? We'll see how easy or hard it is to build. Otherwise, I may spend a whole lot of time handholding kit builders. 

One thing about introducing this as a kit to this community, you'd see a lot of self-sufficiency amongst the group. A couple threads would pop up for people to discuss questions, problems, etc. and those with greater skills would probably be quite a bit of help to those who may
find themselves in over their heads.

No shortage of hand holders in this group...and I mean that the nice way!

[halleyscomet8]

once again, this looks great. i don't think you need so many options. stick with regular xlr's. pick a side for them and stick with it. only offer 1 type of transformer. the more options you give the people here, the more work for yourself. there are a lot of opinions here, and all differ slightly. i would hate to see you run into the ground trying to customize these boxes. also, i would think you will need different names for the transformer one. maybe TST-2 w/ transformer, and TS-2 without,

[willndmb]

i for one wouldn't buy a kit because i don't have the knowledge to put it together right
i also would be worried about buying a used kit based on not knowing if the person who put it together knew what they were doing
but its a great idea for those who want to play around, for my money though get it from the maker direct

[Gutbucket]

Gutbucket and nashphil
I actually prefer all XLRs on one side too, i.e. the back.  I probably misunderstand this thread. I thought the consensus and preferred way was XLRs on the sides?

Either way, I think it will be possible to offer it with XLRs on the sides, or the back.  XLRs on the sides will just cost a little bit more (because of the additional manual labor).

I like the stereo-mini output idea.

This may be doable.  The rear panel okay? If I can find space on the front panel, it will go on the front panel.

You'll likely not want to offer too many options and the choice of which is your own business decision to make. The option for side connections is a big part of the attraction in my mind and would diferentiate this product form others I think, though I completely understand that rear connections would better accommodate rack mounting home or studio users and perhaps others here too.

For field recorder preamp use, most of us keep the equipment in a bag of some sort, with the face pointing up.  Because of that, cables out one side of the unit makes the connections more accessible and keeps the weight of the unit off of those connections.  Most here devise ways of reducing the stress on connectors that do exit the bottom of the equipment- by using right angle connectors, attaching the gear to DIY internal racks or by attaching ears or handles to the back to bear the weight of the device and to allow the connected cables to bend without weight on them.  Devising that sort of protection and support isn't as critical if there is nothing on the back of the housing.  To me, the aspect of all connections on one side instead of the back really denotes this piece of gear as well designed for this type of field use (along with being DC powered of course).

Obviously for typical rack mounting, connections at the rear are preferable.  Some here may prefer that configuration because they have already made provisions for taking care of cabling out the bottom of the gear in their bag.  After all, most professional audio equipment is designed or descended from a rack mount mindset.

The stereo mini output would be fine either on the front face if there is room, or on the same side as the other connectors.  I will say that if any connections are going to end up at the back of the unit I'd suggest something like the handles on the front, feet or some sort of recessed panel/ extended case sides that are deep enough to support the weight of the box and keep it level, and that are deep enough to provide clearance for standard right angle connections (XLR, mini-jack, power, whatever). One problem many of us have with the Grace V3 is its connectors located on the back - using right angle XLR's for the audio signals is not too much of a problem, but a right angle version of the locking power connector is not available.  That places a lot of stress on the power cable sticking out farther than anything else on the back unless the unit is supported somehow.  Again, most DIY a solution or build a custom cable with serious strain relief.  Still, you usually have to pull the unit completely out of the bag to access any of those connections.  I use short right angle input extension cables so that I can leave everything connected back there and live with the extra XLR cable connection points in the mic cables so I don't have to pull the preamp out to connect mics, then re-wedge foam in the bag that surrounds and supports everything.

[fivefishdiy]

Again, thanks for the feedback.

Offering the stock, Cinemag and Jensen trafos won't be too difficult (except for the capital required, i.e. me buying 2 types instead of just one type).  So most probably, the initial offer will be STOCK, and CINEMAG.

The Lundahl option will come later. Depending on demand, if any...

Offering the side XLR option is something that may also come later. So initial offer will be XLRs in the rear.... because that is something I can easily program on my CNC and make easily. 

What I'm just saying is the XLRs are not PCB mounted so changing placement is not a big problem. (* a second revision of the PCB down the road and I may use PCB mounted XLRs if the demand for rear XLRs outweigh the side XLRs... but that's speculating that this pre will even be wanted.)

Gutbucket

I think it will be easy to rig and bolt 2 legs to the backside of the case. Just need an L-shaped aluminum or steel material, drill 2 holes on the L-plate, and screw to the backside using the existing screws on the case.

Will try that sometime... thanks for comments.

[ero3030]

  and ,  i'm luvin this process    ed

[fivefishdiy]

Update for today: Got some time to work on the board, now 99% done, just need to verify a few measurements.

[illconditioned]

^^ What chip are you using for Phantom on that board?

  Richard

[fivefishdiy]

illconditioned

it would be nice if this project stays open.

If you buy any of my kits, the SC-1 preamp (which this new TS-2 preamp is based, but with just a different footprint), or my Power supplies, VU meters, Active DI and others, you get the bill or materials, schematics and instructions on how to build them.  You also get the PCB, and all the parts.... including the screws and nuts and fuses. So I don't know how much more "open" I have to go.  The only thing I don't provide is the soldering iron and lead.

I'm doing a blow-by-blow update on the development of this pre... I don't know how much more open I need to do.

Now, my current DC-DC converter is not released either as a kit or a running product out there in the "wild" yet. I'm not ready to release it yet. In fact, just a few days ago, I've thought of a different way of generating 48Volts and in the process of verifying the new method. So the 48V section you see here may probably still change. Depending if the new method will be better than this or not. This is my 5th revision of this converter PSU.  It was already working fine in the 3rd revision... but was not happy with the amount of noise it was giving out... not when you put this beside a high gain pre inside a small case. So it took 6 revisions to get to where I'm "satisfied" with it. (Had to throw out 100 good PCBs of the 5th revision, costing hundred$ of dollar$, since it didn't pass my muster!) .... now, I'm thinking of doing a 7th revision. So nothing is final yet until the fat lady sings.

Hope you understand.


mshilarious

<thumbs up!>

[illconditioned]

^^ OK, someone said (in a PM) that I should not criticize fivefish, for lack of schematics, or detailed technical information.

I am not criticizing, just expressing *my* opinion that sharing information is good.  I still admire fivefish's work and encourage him to continue with his fun blog as well.

  Richard

[illconditioned]

I on the other hand have worried that he was sharing too much "inside baseball" info that might be of value to competing product developers.  But, knowing that it will all likely be available in kit form eventually sort of brings the wizard out from behind the curtain.  As far as I'm concerned, what he's showing me is beyond my comprehension and what I think he really wants is some virtual field testing done before too many PCBs get burned and ultimately tossed out.  If we can give him a good sense of what qualities a good/great field pre should have, then that's invaluable input from my perspective.  Any trial and error work that can be eliminated will ultimately (hopefully) keep his price down to a reasonable level so that we can all buy the thing. 

As far as I can tell, it is all about finding the market.  Look at what Chris Church has done!  He's offering exactly the product we want, at a great price, and... he's hanging around to support it.  What more can you ask for.

Admittedly this preamp will probably sell less units, but I think the same philosophy will work.

As far as disclosing information, any real competitor can easily buy and/or dissassemble the product.  This is not rocket science.  90% or more is just getting what people want.

Anyway, I wish both fivefish and Chris Church the best of luck.  If only more companies took their customer input so seriously...

  Richard

[strangetapes]

I've been following this thread from the beginning and I must say that fivefish lost me a long time ago with the technical stuff.  Many others may be able to reproduce what he is doing from what he has written here, but they aren't doing it here.  If someone came up with a copy of this pre and tried to sell it here for less, I would still lean towards this one as he came to us for input.  He didn't try to steal someone else's work and then market it to us.

+T Fivefish

[Chilly Brioschi]

...So nothing is final yet until the fat lady sings.

Did the fat lady really sing if no one pulled tape of it?         


I'm really glad to hear that you are willing to put time into getting this thing right.
The effort invested upfront may ultimately payoff.
The new technology has made it possible to put out a Pre that's a cut above, for less than ever, and I'd love to see it happen.

Good luck... and I am serious about the Lundahl option.
I think that presence is under-appreciated, and would venture a wild guess that Lundahl-Schoeps might just be a killer combination.

BTW, does anyone know what Len (Core) based the 2Phant circuit on?
How about the Deneke PS-2 circuit?
They both seem to do "quiet" very well.