DIY Mic Pre

[Jerry Gleason]

There has been some discussion here lately of the importance of good quality microphone preamps for recording. Many home recording enthusiasts have never had the opportunity to hear how much better a good preamp can be, compared to the budget "prosumer" grade pre's, and the stuff that's in mixers and recording interfaces. Most of the good high-end mic pre's on the market are priced beyond the budget of the average home / project studio.

If you're handy with a soldering iron, and want to do a fun project that ends up with something that sounds really good, and save a little cash in the process, I might suggest building one from a kit. The one I would specifically recommend is the Hamptone.

This is a really well designed two channel preamp, offered as a vacuum tube unit, or a JFET based on the same circuit as the tube design, and using similar audio transformers. It's all discrete class A circuitry (no op-amp chips), transformer balanced, and uses top grade components.

I built one of the JFET units last year, and I've been extremely pleased with it. It takes only rudimentary electronics knowledge to build. You need to know how to use a digital volt meter, and be able to make clean, consistent solder joints, but you don't need to be an electronics tech. All the parts are included, and the instructions are good. It took me about 13 hours to assemble, and I took my time.




Sonically, this pre (at least the JFET one, that I built) is slightly more toward the "colored" (in a good way) end of the spectrum as opposed to the "transparent" end, but not so much that you couldn't use it on every track. I haven't done a methodic "shootout" comparison with other high end preamps, but I have used it on the same session with an Avalon 737, and an API 3124. I liked it better than the Avalon, and it certainly holds it's own against the API. It's also one of the best sounding DI boxes I've ever used.

There is another manufacturer of high-end preamp kits, Seventh Circle Audio, that offers some API and Neve clones, as well as a few other interesting designs. I don't have any direct experience with their kits, but they appear to be for the more advanced builder with more electronics knowledge.

Note- I don't have any affiliation with Hamptone, I'm just a satisfied customer.

JG

[John Macy]

I had Scott Hampton build a power supply for my Neumann Tube U47 a few years back and it has been flawless... Might have to try one of these out. I used a couple of the 7th N72 pres and they sounded pretty good, too...

[Bryan Daste]

A friend of mine had a JFET Hamptone that we used for a while. I liked it, but it seemed to run out of headroom and start clipping at lower levels than other pre's. I would like to build the tube one though!

[Jerry Gleason]

This preamp has a LOT of gain, probably close to 70db. I do recall that the input transformers are tapped so that it can be wired for less gain at the input if desired. Mine are wired for maximum gain, but I haven't had any problem with headroom, even with pretty high output mics. I don't record very loud sound sources, though. It is possible to overdrive the DI with a hot guitar pickup, and especially a steel guitar pickup, but setting the pad for line level fixes that,and still gives a huge amount of gain. I think the DI bypasses the input transformer, so hooking up the jumpers on the input tranny wouldn't change that.

At the limit, JFETs will clip pretty smoothly, but I would think that tube version would allow even more of a cushion. One of the things that actually impressed me most about this unit is the amount of clean, quiet gain it has, making it ideal for low output mics like ribbons.

The only problem I have with the Hamptone is that everyone who hears it always wants to borrow it.

[Gibson Hartwell]

I built the tube Hamptone last year and it is very smooth and warm sounding but still very punchy and defined. Building this kit itself was quite fun in itself. I've been using a ribbon microphone and even with that, this thing has plenty of gain to spare.

[James Quackenbush]

I contacted Scott a while back about the JFET pre, as I was looking for something that would compliment a Ribbon mic , and he told me that the JFET would work fine ....I used a buddies Hamptone JFET and it had plenty of headroom for ribbons, and sounded very nice ideed ... It sounds great as a D.I. also for just about any instrument , including bass ...I'm gonna have to build me one .....Jim

[Ray Minich]

Brings back memories of the Benton Harbor folks whose name also began with and "H" (... Heathkits...)

[Terry Edwards]

Great topic. Here's another one but I have not built one and I personally can't comment on the sound quality. Overall I think DIY preamps are very good performers and of couse cost effective.

JLM Audio

Terry

[Michael Garnett]

Man that looks like a sweet way to get some great preamp tone for the home studio. Can somebody let me borrow $700?

[David L. Donald]

Both the JLM and Hamptone look pretty cool.
A bit of geekwork, but the money you save
vs inserted components or buying a
"name brand high end mic pre"
is quite significant.