MC head amp

analog97 · « **on:** 6 Feb 2007, 12:57 am »

Hi. Just wondering if our Trumpet player leader took that earlier thread seriously. Is there a head amp half-kit in our future?

PatOMalley · « **Reply #1 on:** 6 Feb 2007, 01:23 am »

I am hoping so.

BradJudy · « **Reply #2 on:** 6 Feb 2007, 02:14 am »

I'm curious if Jim finds he has something interesting to add to this area. There are a LOT of freely available designs out there on HeadWize and Head-Fi and several good half-kits. This includes a variety of tube, hybrid and solid state (discrete, chip, opamp, etc) amps.

hagtech · « **Reply #3 on:** 7 Feb 2007, 03:13 am »

Yeah, it's called the PICCOLO. Will make a great addition to a CORNET. I am presently tweaking the ARCHIVER, a new JFET phonostage to replace the BUGLE PRO. From that research the head amp will follow.

Probably run from 6V, either wall wart or battery or dc heater supply from CORNET. Probably have rotary switches for both loading and gain. Can build into other equipment or standalone box. Design doesn't look like any of the other schematics you've seen.

jh

analog97 · « **Reply #4 on:** 7 Feb 2007, 09:23 pm »

Thanks very much. Sounds like a relatively simple build and "Bugle-like" in complexity. Let me be your first pre-order.....

amandarae · « **Reply #5 on:** 8 Feb 2007, 03:44 am »

Hey PICCOLO.........my wallet is ready!

Wow! A head amp match and tested with the Cornet in mind!
Please make one with a 14 and 40 ohm settings besides the usual suspects of values, please?

Thanks Jim for the heads up info of upcoming products!

hagtech · « **Reply #6 on:** 8 Feb 2007, 06:23 pm »

I'm thinking along the lines of something like this:

Small metal box. This cover design would fit on one of those cast aluminum enclosures. Sadly, a finished panel like that shown would run $50. So I'll probably just do some sort of weatherproof label like the HAGUSB. Or maybe get some fancy thick plastic decal done up in color.

Could do a small, dedicated stage without the controls. Borrowing this stuff from the ARCHIVER design. Thinking the gain and loading controls will come in handy. Would make it virtually universal in application. Of course, DIYers could choose whatever resistors they want for the loading. Does not have to be the generic ones shown. The ARCHIVER was also a successful attempt at getting a cheap wall-wart to provide power. Careful system design and a LOT of filtering combined with balanced operation made for a very quiet preamp. That allows me to do the same here. The box can be powered directly from a 6V wall wart or the 6V heater supply from a CORNET or similar phonostage. I'll also make the layout conform to the innards of a CORNET/C2 such that it is easy to install into existing units. Add a pair of standoffs, run some wires. Only problem will be the controls accessible from the bottom. But hey, you only have to tweak once. Then put the cover on.

Could also do it with 4 AA batteries inside.

jh

PatOMalley · « **Reply #7 on:** 8 Feb 2007, 07:01 pm »

Why can't we run the controls to the front of the box where the mono switch is?
It's already done that way with the Bugle Pro for the curves switches.

hagtech · « **Reply #8 on:** 9 Feb 2007, 05:20 am »

Quote

Why can't we run the controls to the front of the box where the mono switch is?

Not enough chassis height. Need more space to fit the rotary switch between to channel strips. It takes just under 3 inches. If there were no C2 board, then ok. Alternative is to use right-angle pcb mount switches, like the one in the CLARINET. The problem is getting it to fit sensibly into two different box configurations. And keep the cost down. It is always possible to 'remote' the switches. Not sure how far is reasonable. Fortunately, there are no feedbacks loops to contend with.

jh

analog97 · « **Reply #9 on:** 9 Feb 2007, 03:04 pm »

Active MC head-amps are not cheap in the marketplace, e.g. the Gram Slee and ZYX products are around $1,100 to $2,000. I have no idea what the guts of these are, but from the circuits I've seen so far, my sense is they are relatively simple but well-engineered. By this comparison, it seems as if JH has a lot of "headroom" on this Piccolo project. If the Piccolo competes favorably against the performance of these other products, it should be a big winner in the marketplace.

BradJudy · « **Reply #10 on:** 9 Feb 2007, 07:43 pm »

Depending on the total project cost, I might give this a shot. I'm a sucker for headphone amp half-kits.

It that panel really $50 to run? What are the dimensions? I guess it does have a number of holes and text.

tubesurf · « **Reply #11 on:** 11 Feb 2007, 11:43 pm »

Brad,

I initially thought they were discussing a headphone amp as well but on further reading it seems they are discussing a phono cartridge amp. I think a head amp is an active amplifier for low output moving coil cartridges - it is sometimes used instead of the step up transformer solution. Since the Hagerman Tech phono stages are for high output cartridges this would be a companion if you have a low output moving coil cartridge. A Hagerman Tech headphone amplifier is a product I would be interested in as well (along with all the others).

BradJudy · « **Reply #12 on:** 12 Feb 2007, 02:03 am »

Yeah, I figured that out after taking a closer look at the panel. I have no interest in this particular component and my prior comments about 'would it bring something new' can be ignored.

robertwstephens · « **Reply #13 on:** 14 Feb 2007, 08:43 pm »

I would love to build a Piccolo. I look forward to ordering the 1/2 kit!!! Peace.

Robert

analog97 · « **Reply #14 on:** 3 Mar 2007, 06:22 pm »

RE: PICCOLO........Starting to get lost with all the posts. Will the PICCOLO be offered with a case? Maybe an inexpensive case like the RIPPER??

hagtech · « **Reply #15 on:** 7 Mar 2007, 03:54 am »

The PICCOLO half-kit will not have the case included. It is a low-cost aluminum box from digikey that is easily drilled. Only round holes! I will provide cutout or label info. Just mark the spots and drill. The board can be built and tested separately. Then you mount board to inside of top cover. The standoff turns into the GND lug. It will be just like the production version, but without the fancy paint job.

I will, however, include the six pieces of 2SK389 dual JFETs. That's why the $59 price.

jh

PatOMalley · « **Reply #16 on:** 7 Mar 2007, 04:05 am »

the pix for the Piccolo are not displaying on hagtech.com

hagtech · « **Reply #17 on:** 7 Mar 2007, 06:53 pm »

Yeah, I know. That's because they don't exist yet. I had the choice of posting the proto circuit board, but thought that might be misleading. The end product will be in a nice painted box with silkscreen. I should probably put something there though...

jh

PatOMalley · « **Reply #18 on:** 7 Mar 2007, 09:00 pm »

you could put the links form the blog ...

could a standoff situation be made on the Bugle? And use the internal power supply?

hagtech · « **Reply #19 on:** 7 Mar 2007, 09:18 pm »

Quote

could a standoff situation be made on the Bugle?

I'll look into this. Boards might be same size. I just need to line up mounting holes. Hadn't considered this possibility, since the BUGLE can run 60dB gain. However, the PICCOLO should provide a quieter solution and give you the loading adjustment. Could make a nice stack of three boards. Glad you thought of it.

jh