Hagerman Bugle 2

My Bugle 2 is up and running

Anyone built the Bugle2 ?
I was a sponsor of the Bugle 2 on kickstarter, and I built it the weekend the kit came in. The resistors are super-small and the colors are very hard to read, so I ended up measuring every one.

The build was easy - just a matter of taking things slowly. I implemented 40dB of gain, and used all the stock parts.

The preamp is replacing my EAR 834P, and doing a great job.

The first thing I noticed was that it's really quiet, despite being powered by a wall-wart. I cannot hear any noise or hum at all.

The second thing I found was that it is simply very transparent. I've been tweaking tracking weight and angle, and it's easy to hear the effect of changes.

I am enjoying listening to a lot of vinyl (I had to pull out my Nitty Gritty cleaner so I can listen to some old stuff). It's a real pleasure.

tim
 
What's the difference between the 'Bugle' and the 'Bugle 2' ?

The Bugle2 is a second generation of the original Bugle.

Here's what Jim Hagerman has to say about the original Bugle design:

  • The Bugle is a low cost solid-state phono preamplifier. It utilizes a split, passive RC-type equalization network that offers excellent flexibility for customization. The circuit is not the typical "feedback" type commonly used, but rather uses the opamps as pure frequency-independent gain stages. Two of these gain stages drive the equalization networks followed by a third gain/buffer stage to provide a low output impedance. The overall gain is thus optimally split between the three stages.
 

6L6

Moderator
Joined 2010
Paid Member
I've been looking at making my own opamp phonostage. (Well, from a app. note, but you get the idea)

Recently I found out about the Bugle 2. Looking at it I see a few very clever things I would do on my phonostage.

But mostly I have found that I'm not very interested it trying my own anymore, and just want a Bugle 2... :) :) :)
 

6L6

Moderator
Joined 2010
Paid Member
The PSU is different, so is the filtering. There are a couple tricks in the PSU that I find very clever and I want to try in the future.

The Opamps are different, look at the photo, not the schematic.

But yes, the basic idea is very similar to the original.
 
Please Tim can you describe the differents between your EAR and the Bugle2?


Hans.

I'm somewhat skeptical of my own ability to be objective about differences between equipment when distortion is already very low, and probably swamped by other effects.

The EAR is a very good preamp - quiet, unfussy, easy to use. It has the advantage of a built-in step-up transformer (for the days when I could afford a moving coil cartridge). I have it completely stock, except that I added tube dampers as tube phono stages are very sensitive to microphonics because of the low signal levels.

The Bugle2 is quiet, clear, and completely seems to get out of the way. I find the differences between LPs are very clear, and I can also hear changes in VTA or tracking force pretty well. It basically seems to be good enough that I can now forget about improvements in that area, and focus on other areas of my system (I'd like more gain, thinking about remote control, bi-amping, active crossovers etc.).

Not sure that helps - let me know if you have any specific questions.

tim
 
I'm somewhat skeptical of my own ability to be objective about differences between equipment when distortion is already very low, and probably swamped by other effects.

The EAR is a very good preamp - quiet, unfussy, easy to use. It has the advantage of a built-in step-up transformer (for the days when I could afford a moving coil cartridge). I have it completely stock, except that I added tube dampers as tube phono stages are very sensitive to microphonics because of the low signal levels.

The Bugle2 is quiet, clear, and completely seems to get out of the way. I find the differences between LPs are very clear, and I can also hear changes in VTA or tracking force pretty well. It basically seems to be good enough that I can now forget about improvements in that area, and focus on other areas of my system (I'd like more gain, thinking about remote control, bi-amping, active crossovers etc.).

Not sure that helps - let me know if you have any specific questions.

tim

I have the EAR a little tweaked; swapped tubes for Full Music 12AX7 and the 1 uF cap. for a tin foil paper in oil.

D`nt use MC carts anymore. Prefere MM.

I do like the wide and open stage.

Do the Bugle have this also?
 
I have the EAR a little tweaked; swapped tubes for Full Music 12AX7 and the 1 uF cap. for a tin foil paper in oil.

D`nt use MC carts anymore. Prefere MM.

I do like the wide and open stage.

Do the Bugle have this also?

I'm using large corner horns, so the speakers really drive the soundstage. With vinyl and with digital sources the image spreads evenly across the entire room.

So at least I can say the Bugle2 is not reducing the soundstage at all. As with digital sources, records vary a great deal. The location of instruments is generally easy to determine.

tim
 
I have the EAR a little tweaked; swapped tubes for Full Music 12AX7 and the 1 uF cap. for a tin foil paper in oil.

D`nt use MC carts anymore. Prefere MM.

I do like the wide and open stage.

Do the Bugle have this also?

There are options for 40, 50 or 60dB gain and either 47Kohm (mm) or 100 ohm (mc).

So either MM or MC can be made.

I have made mine 60dB and swapped the 100 ohm resistors for 200 ohm as the VdH DDT-II is best suited to that.

THinking of dropping the gain to 50dB as the o/p is .6mV
 

6L6

Moderator
Joined 2010
Paid Member
Building the Hagerman 'Bugle 2'

Hagerman Technology LLC: Bugle2 Phonostage

I recently bought the Hagerman Bugle 2 phonostage as a DIY kit, and this shows how, step-by-step.

This phonostage sounds absolutely wonderful! It shows exactly how good of a quality you can get from modern opamps and some very clever engineering.

Where the original Bugle used two 9-volt batteries for power, the Bugle 2 uses a universal AC-DC power adapter, and a very smart design in the preamp's PSU. It's quiet, cool, and simple.

IMG_1899.jpg

Opening the package the first thing to do is locate the paperwork. Included are a very nice manual, covering assembly and testing, a resistor stuffing guide, and a piece of paper for sorting the resistors.

IMG_1900.jpg

Here is the full contents of the kit - manual, very neat looking translucent case, power adapter, circuit board, and a bunch of parts.

IMG_1901.jpg

The first job is to sort the resistors. Sort by color code, or better, measure them and verify the color.

IMG_1902.jpg

The resistors are the first to install on the PCB. Do yourself a big favor and align all the brown stripes in the same direction. This will greatly help with troubleshooting if you make an error.

I also strongly suggest that you measure every resistor again before placing in the PCB. You will make mistakes, and the only way to catch them before they turn into a problem is to measure.

IMG_1903.jpg

Trim the leads once soldered. (It sounds obvious to say this, but I have an amateur -built Heathkit multimeter that has a forest of un-cut leads on it's PCB… Go figure.)

IMG_1904.jpg

Keep following the instructions to stuff the PCB.

IMG_1915.jpg

A quick note on the opamps, the DIP-8 package (these little computer-chip looking things) have the dot at pin 1. Easily seen here.

IMG_1916.jpg

The PCB has a square pad at pin 1.

IMG_1918.jpg

So the proper orientation looks like this.

But before you install the opamps, it's actually a good time to make a few quick checks.

(NOTE - if you are a first-time kit builder, follow the order that Hagerman says in the manual. If you leave the opamps out until this step they are tricky to install and solder. The instructions are very good. Ignore them at your own risk.)

Checking PSU voltage and polarity.
This kit is quite simple and very well laid-out, but it never hurts to check along the way and make sure you are building it correctly.

Before applying power make sure the 'can' capacitors have all been installed correctly - they have a polarity. The + lead is marked with the longer lead, and the label itself will have a marking on the - side.

Also make sure that the stripe on the diode aligns with the stripe on the PCB. It's there to protect against a backwards PSU, but if it's installed backwards it's not going to do any good.

Now plug it in. Does the LED light? Good! (The provided one is yellow. I used this color because I like it better and happened to have a couple laying around.)

Now place the minus (black) lead of your multimeter on the ground screw thing and set the meter to DC volts.

IMG_1913.jpg

Read the voltage from the top of the resistor in-between the two can caps. It should read +12V (or probably just a bit lower)

IMG_1914.jpg

Reading from the bottom of the resistor opposite the one you measured in the previous step should show just a bit less than -12V

If your voltages are good and of proper polarity, install the opamps and continue.


A geeky diversion -

What attracted me to this phono preamp is the use of the LM4562 (an opamp I've been interested in for some time) and the very clever PSU to power everything.

The DC starts from a little switch-mode AC-DC adapter outputting 24V DC. It being a SMPS, it has very nice DC coming out from it but it does have some high-frequency hash like they all do.

Here is what it looks like -
IMG_1908.jpg

The base line is nice and stable, but there is high frequency junk at the beginning of the wave.

Ok. So what does that mean? It means that at high frequency that PSU rings and makes some 'noise'. (Ultrasonic, BTW, way above the audio band.) This is very common in modern wall-warts.

So how the heck is it fixed? Simple - inductors! (Also known as chokes) Because the current draw of this preamp is fairly low, some high-value chokes can be placed on the PSU input and all the junk and grime hits a brick wall.

How good of a job do they do? Look - (and the oscilloscope settings haven't been changed)
IMG_1909.jpg

Wow - that's significant. The hash is now gone. What's different? Only that I am measuring downstream of the chokes.

As long as the scope is hooked into the PSU, let's 'zoom in' quite a bit until we can see the residual of DC ripple.
IMG_1910.jpg

The scale is now 20 millivolt/division (the previous photo were .5V or 500millivolt/division) and you can see a very nicely behaved DC supply with no leftover weirdness. Measured from the same point as the above photo, just downstream of the chokes, near the output opamp, which has the least amount of filtering!

But there are still more tricks left to show - the PSU as an additional layer of RC filtering for each opamp, meaning that the input circuit has a much quieter supply. This is important because it's the one that handles the teeny little delicate signal off the cartridge.
(One thing to keep in mind is that opamps have very good PSRR, or power supply rejection ratio, meaning how much PSU noise the device (opamp) can reject all by itself. So making a supply this quiet is icing on the cake. I like that!)

Look at this last scope shot - it is the same scale as the photo above, but the probe in now placed near the input opamp.
IMG_1911.jpg

Ripple? What ripple? :cool:

That's good engineering.

Ok, back to building. :)

I'm a card-carrying member of the "Can't leave anything alone" club, and made a couple substitutions on my project.

IMG_1919.jpg

As I am wanting to use this preamp with both MM and MC cartridges, it makes sense to have the resistors that set the gain changeable somehow. Instead of wiring up a switch, which would look kludgey no matter how it's done, I opted to use these pins. Stolen from a really nice DIP socket, they are soldered in, and now the leads from the resistors can be inserted and removed from those pins. A simple solution, and quite handy when I feel like using a low-output moving coil.

IMG_1922.jpg

Here is is with the resistors installed. Why none on R23? I ran out of pins. :) (And also because it's left empty for the 40dB setting)
Remember, these pins are not supplied with the kit, so if you are confused because you are not reading the text, that's why.

Also, some of you are probably wondering about the silver flying saucers that are now on the board --- remember how I mentioned I was attracted to this preamp because of the LM4562? Well I had the idea of making my own phono pre with them, and got some in the fancy (and expensive) TO-99 package. Then I found this project, scrapped the plans to make my own and in memory of that idea, used the fancy-pants opamps in this circuit. They are completely the same on the inside as the ones in the plastic. They just look cooler and are harder on the wallet. (Almost 8 bucks each.)

IMG_1921.jpg

I thought the ground lug assembly was pretty cool. Here's a photo.

IMG_1923.jpg

The last thing to do is put the case on, screw it together and place the sticky feet on the bottom.

IMG_1924.jpg

The translucent case looks very cool lit up.

So… How does it sound? In a word, Wonderful. It is quiet, supremely musical, and unobtrusive. As I've been writing this guide my turntable has been spinning, and I am really, really liking it. Dynamic and transparent, the Bugle 2 is just getting out of the way and letting the music flow. This thing punches so far above it's weight class it's ridiculous.
 
Last edited:
  • Like
  • Thank You
Reactions: 1 users