Inside The Universal Audio M610 Vacuum Tube Preamp
The M610 preamp is the same tube preamp used in the LA610, LA610 MKII and 2-610. The preamp is made up of two separate feedback gain stages that are cascaded one after another.
The UA M610 Circuit
The first feedback gain stage can be adjusted with the "GAIN" switch on the upper left of the front panel. This switch selects a feedback resistor that can add or subtract gain to the circuit. The first tube in the circuit (left tube) is a 12AX7 dual triode.
The following feedback gain stage uses a 6072 (right tube). The 6072 is similar to the 12AT7 dual triode. Notice that the big knob says "LEVEL". This is because it acts like a volume knob and not a gain knob in the circuit.
The first feedback gain stage feeds the 250k ohm "LEVEL" potentiometer and you adjust the input level to the following 6072 feedback gain stage.
More info and measurements coming soon.
Thanks for reading,
Part 4 of my video series on How To Build A 12AX7 Gain Stage. This video covers DC measurements, AC gain measurements, and frequency response measurements. SPICE simulation is then compared to the real-world tube circuit.
Two out of the four absorber kits are finally mounted on the wall using the supplied Z-Clips. TIP: You can gain a little more room "absorption" by spreading out your absorbers a bit. This is due to "diffraction", or "bending" of the sound wave. When a sound wave bends around an object, some of the energy is reduced giving an apparent increase in "absorption"
Since these absorbers are fairly large I needed to make sure to anchor them well. Here you see the supplied Z-Clips mounted to the wall spaced 12" apart. Note: they are not perfectly mounted. In fact, not a single piece of my hardware is exact.
Remember, it's more important to get it up and on the wall than it is to worry about having it perfectly mounted. Just make sure it's NOT going to fall off the wall.
Zinc Self Drilling Drywall Anchors
For the right absorber I got lucky and hit wall studs so I just needed long drywall screws for both Z-clips. For the absorber on the left I used zinc self drilling drywall anchors (shown below). You use a drill to drive them right into the drywall. Then you use small screws to mount your Z-Clips.
I recently ordered (4) DIY422 Panel Kits from Acoustimac in Florida. These absorbers measure 48" x 24" x 2". Although I usually order my panels with Owens Corning 703, this time I decided to try something new and ordered the Roxul Rockboard core material.
When I saw the images online I thought I would be building everything except the frame. However, you can see the image below of how they came right out of the shipping box. The only thing left to really "DIY" is the fabric covering. Everything else was pre-assembled.
ROXUL ROCKBOARD CORE
According to Acoustimac, Roxul Rockboard has better absorption properties than Owens Corning 703. I'm not sure I'll be able to detect the difference in my tiny room.
I will be hanging two of these
panels from my ceiling as a cloud absorber. The other two will go on the wall. I will be installing hardware in each corner of the frame to allow me to attached cables from the ceiling. Access to the inside of the panel is the main reason I ordered kits.
I feel Acoustimacs prices are very fair. Each of these 48" x 24" x 2" panels were only $42.00 each including fabric. I will post more as I finish them.
Added simple eye bolts to each corner for hanging.
I'm not sure if it helps but I rounded off the frame edges and corners using a belt sander. Image below of an absorber that is going on the wall. (Not the ceiling)
As the sun goes down I put the fabric on. Make sure to use a good staple gun. I used an Arrow T50 with T50 1/4" staples #504. (Image of a wall mounted absorber)
It's now dark outside as I mount the "Z Clips" that are supplied with the kit. (Wall mounting only) The panels are 24" wide so I mount the clips 6" in from each side and 6" down from the top.
More coming soon: Finishing up the ceiling absorbers and installation.
110 Sound Room Demos | 40 Headphone Demos | 17 World Class Seminars | Loudspeakers | Turntables | Home Theater | Car Zone | Marketplace | Beer Zone | Live Music | Giveaway | Awards
June 2-4, 2017
Sheraton Gateway Hotel
Los Angeles, California
The LA Audio Show, hosted in collaboration with The
Los Angeles & Orange County Audio Society is the US West Coast's
epicenter for discovering the best and latest audio technologies from
leading global manufacturers and dealers.
Every now and then my 1176 kit gets a little "wonky". So, I'll go in and poke around a bit until the trouble seem to go away. If you have built your own 1176 kit and have experienced strange issues, you might want to check out the new F.A.Q. section at Hariball Audio.
Keysight has traditionally been a high end scope manufacturer. But, now they are finally getting more aggressive to compete with Rigol and Tektronix. The InfiniiVision 1000 X-Series of two-channel oscilloscopes have bandwidths of 50 MHz, 70 MHz, and 100 MHz
Get the full scoop at EDN.com
Thanks for reading,
There are a few differences between NAMM and AES that I would like to share.
NAMM is a "trade only" conference, not open to the public, where you see a ton of new gear, meet your favorite companies, and learn what is going on in the music instrument industry. To get into the show you need to either be a NAMM member or know someone that can get you a badge.
This year marks my 13th year attending NAMM show. Below is an image I grabbed of a vinyl cutter at NAMM show 2017 in Anaheim, Ca. This is a very good example of the cool stuff you can find at NAMM show. You won't typically see this at AES.
AES, is a technical committee type show where you go to find out what is happening "technically" in the audio / video / film industry. Anyone can get into AES show. It' just costs a little more for non-members.
AES has a small showroom of pro-audio equipment, but, nowhere near the size of NAMM show. However, AES is much quieter. So, you can actually have normal conversations with people on the showroom floor which is very hard to do at NAMM show due to the intense noise levels.
Below is an image I grabbed of Steven Slate giving a presentation at AES 2017 at the Los Angeles Convention Center. AES makes it so much easier to sit down and actually enjoy the presentations.
At AES there are a ton of technical committee meetings, regarding film, video, and audio. I highly recommend you sit in on a few to gain some industry insider information. There is also a job board posted at AES. Something I have never seen at NAMM show.
I hope this help clarify some of the differences between NAMM and AES shows.
Any questions can be posted here or look me up on Twitter @Trent_Blizzard and direct message me there.
You can learn to make your very own humbucker and single coil pickups at the Roberto-Venn School of Luthiery located in Phoenix, Arizona. Below is an image of the humbucker I made during class.
Custom Wound Humbucker
Who Can Take The Class?
This class is open to anyone interested in making guitar pickups. You do not have to be enrolled in the luthier program to take this class.
However, you will be attending the class along with the students who
are enrolled in the program.
Who Teaches The Class?
This class is taught by professional pickup designer Jason Lollar. I really enjoyed hanging out with Jason after class on Sunday and talking shop at a local bar.
How Long Does Class Last?
Class is typically held on a weekend and pretty much goes most of the day both days. Sunday is a little shorter because the single coil doesn't take quite as long to build as the humbucker does. Below is an image of the single coil I made during class.
Custom Wound Single Coil
Is It Hard To Do?
Winding your own pickups is not rocket science. However, it is very detail oriented. So, if you have basic mechanical skills and are not too
intimidated by machinery you should do just fine
Was It Worth It?
I think it's totally worth the money. It's especially worth it if you are interested in making pickups and would like to have a professional designer show you how it's done.
I had a great time in class because everyone there was totally into guitars, pickups, gear and music. I also learned a few tips and tricks along the way that really help me out with my own pickup builds. If you are interested in making your own pickups then I highly recommend checking out the pickup building class at the Roberto-Venn School of Luthiery.