Well I'm firing it up tonight...

I got the word from Scott that indeed the ground will go from the board to the chassis. I had also done a test on my Mackie board and found that pin 3 did have continuity to the chassis in their boards as well.

I'll let you all know how it turns out.

Well I've got it up and running now. It's been burning in for a couple days now and I've been playing with it. I definitely love the sound of it so far. It has way more detail and big-ness than my Mackie XDR's do.

Sorry guys, I inadvertently posted this in the wrong group. Below is the message I posted to way more people than I should have...

Hi Guys-

I've been lurking and reading about your progress with the JFET pre. I just finished my tube kit pre and am very happy. Happy that I didn't have to troubleshoot any problems and that there was no smoke!

Question 1: I have noticed that the pre-amp will distort if there are any air pressure changes in the room (door closes or if I walk too close to the mic, within 4 feet). Even if I just wave my hand 6-8 inches in front of the mic, I will hear a soft distortion that kinda sounds like a cat purring. After 2 or 3 seconds, the air will stabilize and the distortion will go away. I am concerned with this noise, because I do mostly live concert recording with the mics up 10-12 feet. I don't want to be concerned with A/C or ventilation disturbance. FYI, I have tried putting wind screens on the mics, but the noise is still there.

In the build instructions, Scott mentions that there is a feedback capacitor included in the kit that he feels is unnecesary unless there is a certain high frequency oscillation/noise in the channels. But he also says that this problem could manifest itself during loud transients resulting in the pre amp distorting.

Do any of you guys remember if the JFET had such a feedback cap? Am I way off base here or does anybody have any ideas?

The second question has to do with the difference in output between the two channels. I don't expect them to be perfectly matched, but I end up having to crank up the pot on Channel 1 about twice as much to get a good stereo balance with Channel 2. Not a big deal, just wondering why there would be such a big difference between two identical audio boards. Will there be different sound characteristics with one channel being cranked up so much more than the other channel, since tubes are involved? I would be curious about how equal the channels on the JFET were.

Thanks for taking the time to read this. If anyone has ideas, I'd really appreciate it.

-Steve

Hey Steve,

On my HVTP2 I haven't noticed any problems with air pressure or any of the kind of stuff you've described, it almost doesn't sound like it is related to the pre. What kind of mic are you using? It's possible that this may be related to phantom power issues...have you tried a straight dynamic mic or a different one? The only other thing I could thing of is possibly a bad tube, microphonics or some other tube wackiness.

As for the channel volume issue I am not experiencing this either. Did you make sure you put the right tubes in the right sockets? There were two different types and each channel gets one of each. They might have different gain structures so even though they might work the volume would be different. That's my only thought...

Thanks Aaron for your quick reply.

Now that you mentioned it, one of my 6072 tubes looked black on top instead of the mirrored silver. A friend of mine told me that that is a sign of oxygen leaking in and a precursor to the tube going out. I will get another tube or even try swapping the 6072s to see if the gain issue jumps to Channel 2?

I have been using large diaphragm condensor tube (read Chinese) mics that are pretty decent and I have A/B'd the HVTP2 with Avalon737 using these mics. Upon closer listening, I found that both of these micpres are making that distorting sound, but the Avalon737 is MUCH quieter (the distortion). Actually, I have been extremely excited and impressed with how great the HVTP2 sounds compared with the Avalon stuff. The HVTP2 is very audible when it distorts. My example of simply waving my hand slowly several inches in front of the mic hooked up to the Hamptone, will give you the distortion while doing the same with the Avalon will not. I will try a few different mics though.

Hope I wrote that last part clearly enough. I am very happy with the sound of the HVTP2. I just want to make sure that something isn't wrong with it. It definitely seems to have a higher gain(?) than my other gear. Maybe that's just my ears talking...

Aaron, by the way, did you install the feedback capacitor C7 in your pre? I haven't heard any high frequency oscillations or abnormal noise floor. Just curious...

Thanks again,

Steve

Yes I installed the lower valued cap in the C7 location. In the documentation it was listed as 2.0 but label on the cap said 2.2. Either way I went with the lowest value. I wasn't too clear about the not installing it part i.e. whether you had to then jumper that bridge or not so I just went with the low value.

That one tube doesn't sound good. I think you've got a good idea with swapping them for sure.

I'm curious to know if you'll have the same problem with a not phantom powered mic. I've only been testing with dynamics and DI's so far, I'll try and throw on a condenser tonight and see how it sounds.

Sorry Aaron, I forgot to mention that the condensers I have tried are not phantom powered. They have their own power supply. I have tried a couple of small diaphragm omni AudioTechnicas, with phantom, and had the same disturbance/distortion as with the tube condensers. I'll swap out the tubes and take a listen tonight. Thanks for all your help and ideas. I'll ask Scott about the feedback cap when I talk to him...

-Steve

Hello,
I am building the original LCMP by Hamptone and I had a question that maybe someone could answer.

I am using 22 AWG wire for point to point wiring and for the attenuator. My question is does the wire have to be shielded?

Also, when you hook up the pilot light, where do you solder it to? (apparently it is supposed to go across the phantom power in series with a resistor, but I am not sure where to 'put it across').

Thanks!

cheers
Andrej

quote:

---

My question is does the wire have to be shielded?

---

Bear in mind, I have not seen the schematic for this. Use screened wire for the inputs at least, from the mic in connector to the input on the board. Your mic is typically outputting 0.05 V, there is 200 - 300v DC & 110/220v AC competing with this! Help that signal as much as possible. As a rule I use screened cable for ALL audio connections.

quote:

---

across the phantom power in series with a resistor, but I am not sure where to 'put it across').

---

Sounds like it will go across the 48v supply anywhere before the phantom on/off switch.

Peter

Hello,
I am building a Hamptone pre-amp and have gotten a lot of help from Scott. I thought it might be nice to buy a gift basket or something for Scott. I noticed he has pictures of dogs up and thought a dog/person gift would be cool.

http://www.creativegiftpackaging.com/dog_gift_baskets.htm

anyway, anybody who would like to chip in can email me at :<"removethispart"andrejcuturic@hotmail.com>

cheers
Andrej

I've been thinking about buying the dual JFET kit for a while now. I noticed that it went up $50. I think the kit was $499 when it first came out. Does anyone know why it went up?

My main pre's now are an Avalon M5 and a 737. I would love to know how the JFET pre compares to the M5.

I know you all like the tone of the pre, but spending $549 + shipping seems like a lot for an unbuilt pre. I know there are lots of good components in the kit.

I think the pre uses pots. I swore that I wouldn't buy another pre that used pots again. I like the idea of a switch with resistors better. It's so much easier to make presets and the sound is usually better over the long haul because pots use a wiper to make the connection which can become scratchy.

Thanks for all the input so far.

Bob

Rjkool,

I know Scott has been contemplating raising the price from before he started shipping the first batch. I think there was a lot of stuff he didn't figure in like time answering emails, dealing with vendors (and their issues), etc. I still think it is well worth the money. I also think the price was lower just to get the word out to people.

I am considering buying another kit because I have found it so versatile and musical. I have discovered that it sounds a bit cleaner without the pad and a little thicker with the pad on and the gain cranked a bit. Enough to make a noticeable difference. Both sound great.

The kit does come with pots but that doesn't mean you can't change it yourself. There are some schematics I have seen around that show you how. Shouldn't be that big of a deal.

Can't compare it to the Avalon. I have no experience with the M5.

Hope this helps.


Jason A.

Thanks Jason.

Hi Bob-

First off, I haven't built one of the JFET kits yet. I have built the tube kit (HVTP2) just a couple of weeks ago though. More importantly, in your case, I also have a pair of 737's and a 2022 (dual channel version of your M5). I must admit, I have not taken it out into the "real" world to give it a try yet, maybe this weekend...

I have compared the HVTP2 to the 737s and the 2022 with a few different mics in my basement (it's not really a studio since I do most of my recording on location) and my first impressions are (1) the Hamptone has a lower noise floor than the 737s, (2) the unit has plenty of gain, and (3) comparing a tube pre to the 2022 might seem a little unfair, but I was stunned to hear how well the Hamptone compared to the Avalon.

Keep in mind that all this is subjective, I have no scientific measurements to back up my statements. I'm just going on my ears and what I am hearing as I talk into the mics and listen to the sounds in my basement as I crank up the gain on each pre-amp. If you have any other specific questions as to how each unit performed against the Hamptone, please ask away.

My observations are that the Hamptone is an incredible piece of gear. $550/$700 might seem like a lot of money for an unbuilt pre, but ALL of the components, and the design, are top notch. Talking to Scott Hampton, I became aware that he loves to design this stuff and he made sure that no corners were cut that would compromise performance. What Scott told me is that, as far as the tube kit goes, he basically wanted to design a pre that would give the same performance as his $4000 Silverbox in a much more affordable package. Now, to do this, he had to make some changes. One change was to give the kits pots instead of step attenuators. The step switches are not cheap! He told me the pots he chose for the kits are pots that he has used for years and have been very reliable. The time and care Scott took in the tube kit is also there in the JFET. Keep in mind that with the $550 you are getting TWO channels of very clean, quiet amplification. I don't doubt that this pre will go head to head with any $1000/per channel unit out there. Like I said, take this with a grain of salt, this is just my opinion. By the way, if you are familiar with Fletcher at Mercenary.com, he has been begging Scott to build more of the Silverboxes. Anyone who has read Fletcher's comments in various groups knows how opinionated he is about what he sells.

One thing is for sure, Scott is not making that much money on these kits. His profit margin is much lower than most other companies, even lower when you consider the amount of time he spends answering questions and offering help/advice. Trust me, I know. He has spent hours with me talking about the kits and other audio related stuff. His dedication and excitement for the project is admirable and I am very happy to have bought his gear.

If you are a DIY-er and you enjoy building stuff, you will not be sorry. If this is your first attempt at a kit, and you have no soldering experience, things might be a little rough going at first and you might get frustrated. But there seems to be plenty of support with this board that I'm sure you will get through it and you will feel, like others here, that extreme feeling of satisfaction and pride every time you fire up your Hamptone and hear just how great it sounds! (It's also a helluva lot easier to carry around than your 737!)

I wouldn't let the pots keep you from ordering one of these kits. Like Jason said, you could eventually put in step attenuators. Scott might even offer an upgrade someday for the same switches that are in the Silverbox...

The kit is designed so that you can substitute a step attenuator to the pot if you prefer. You'll see them in the prototype pictures on the site. There is even an anti-rotation hole for them in the chassis.

Of course this means you need to buy the step attenuators if you want them...

That all said I've built the Tube kit and loved the sound of it. I'd say it's a mildly colored very quiet and really makes things sound large, clear and beatiful.

Thanks for your input guys. I have a degree in electronics, although it's pretty old now, so I shouldn't have too many problems building the kit.

I'm even thinking about buying the tube kit too. When I went to electronics school, we learned about tubes, but in the solid state semister, they told us that tubes would be obsolete very soon.

Now, I really wish I wouldn't have believed them and would have stayed in audio electronics instead of going into computers.

Steve, So do you think the Hamptone tube pre is the same as the 737, or better or worse? There are things on the 737 that I don't use at all, like the compressor and EQ.

Thanks guys!

Rade

Rade-

It took me a few minutes to pick my jaw up off the floor after I read your post. I hope I didn't mislead anyone with my reply about the Avalon stuff. The 737 is a GREAT channel strip. The opto-compressor is superb in my opinion and the EQ is wonderfully musical and has saved my butt on numerous occasions. As far as the mic-pre stage goes, let me just say that for most recordings, it has been the first pre I reach for. It certainly is a Class A unit.

Even though the Hamptone doesn't have 1/4 inch thick brushed metal faceplate and the VU meter, doesn't mean it isn't as good as the Avalon. Since I haven't heard the Hamptone in action, I'm not sure I can say it is better than the Avalon yet. But my opinion so far is that it is very quiet and given the design, should be as useful as any of the Avalon mic-pres. I will be sure to let you know as soon as I have tried it though.

Now, back to the 737. I admit, I was the same as you the first few times I used the 737, only using the mic-pre. But then one day a client of mine requested that I process some of his recording in order to get some of the peaks under control and give the sound a more rounded, warm tone. I first tried some software compression and that didn't seem to be what he was looking for. So I went ahead and ran the tracks through the Avalons. We were amazed at how nicely the compressor did the job and I was impressed at how easy it was to use this thing. I mean, nothing can really sound bad going through these 737s. They are quiet, extremely high build quality and the EQ is very useful both during recording and post work. If you haven't used the comp and EQ on that thing, you haven't yet experienced the power of the 737.

What type of recording do you do? I do mostly classical, choral and some vocalists. I have used the 737 to record a couple of solo piano CDs and I think they sounded great.

Also, what do you record to? If what you need is a clean quiet sound, you might want to start with the JFET. If you don't mind a little color and could use the fabled "warmth" with a nice big bottom end, maybe you should try the tube kit. Either one I'm sure you will find useful.

-Steve

Steve,

I mostly record my own rock/pop songs. I use my Avalon M5 and 737 for tracking mostly. Since I normally don't use eq while tracking, I don't use the eq much. Sometimes during a mixdown, I'll run the lead vocal thru the 737 then back into the board. Then I'll use the eq and compression. I have to say that the compression wasn't as good as I thought it would be.

If I had two 737's, I'd probably use them in stereo at mixdown time.

I have a few tube mics (Soundelux U99 and Rode NTK) that I always run thru the M5 cause they sound better that way. Sometimes my U87 sound better thru the M5 too. This makes me wish I would have bought a 2022 instead of the M5.

Sounds like the JFET should be your first choice if you wish you had bought the 2022. For two channels, you would save a ton. Heck, for almost half of what I paid for my 2022, you could get the JFET and the tube kit!

Good luck in your decision,

-Steve

I don't know how many folks are still paying attention to this thread, as I know a lot of you have finished your preamps and are happily tracking away. HOwever, I have only now had some time to get going on my kit, and am at the power supply testing phase with a problem that I'm hoping someone can shed some light on. Everything's been going fine, the posts here have been helpful, I've been careful and it all looks great but: When I test the power supply (without the B-50 rectifier(?) installed - only the B-30) I get 26 volts on what should be the 48 volt conductors and a -5 volt reading on what should be the 25.5 volt ones, and the way I read it there shouldn't be any reading on the 48 volt conductors without B-50 installed. I examined everything closely, polarities all seem right, soldering looks good, can't find anything wrong. Any ideas? Thanks to one and all!