AMB Laboratories DIY Audio

[gumleguf]

Hi Ti,

I looked at the specs for the opamps suggested and ended up with the following list. I can see that the TI Burr-Brown OPA132PA and TI Burr-Brown OPA134PA can be used for 36 V operation, but what about all the +-18 V, e.g. like the Analog Devices AD744JN?:

Analog Devices AD8610AR (SOIC-8) (Digi-Key, Newark):
Dual-supply operation = ±5 V to ±13 V, Absolute maximum rating = 27.3V

Analog Devices AD8065AR (SOIC-8) (Digi-Key, Newark)
Wide supply voltage range = 5 V to 24 V, Absolute maximum rating = 26.4V

Analog Devices AD744JN (DIP-8) (Digi-Key, Newark)
Operating Range = +-4.5 V to +-18 V, Absolute maximum rating = +-18 V (Does this mean that it can handle 18 V + 18 V = 36 V. So I can use this opamp?)

Analog Devices AD825AR (SOIC-8) (Digi-Key, Newark)
Operating Range = +-5 V to +-15 V, Absolute maximum rating = +-18 V

Analog Devices AD843JN (DIP-8) (Digi-Key, Newark)
Operating Range = +-4.5 V to +-18 V, Absolute maximum rating = +-18 V

Analog Devices AD845JN (DIP-8) (Digi-Key, Newark)
Operating Range = +-4.75 V to +-18 V, Absolute maximum rating = +-18 V

TI Burr-Brown OPA627AP (DIP-8) (Digi-Key, Newark)
Operating Range = +-4.5 V to +-18 V, Absolute maximum rating = +-18 V

TI Burr-Brown OPA637AP (DIP-8) (Digi-Key, Newark)
Operating Range = +-4.5 V to +-18 V, Absolute maximum rating = +-18 V

TI Burr-Brown OPA132PA (DIP-8) (Digi-Key, Newark)
WIDE SUPPLY RANGE = ±2.5 to ±18V, Absolute maximum rating = 36 V

TI Burr-Brown OPA134PA (DIP-8) (Digi-Key, Newark)
WIDE SUPPLY RANGE = ±2.5V to ±18V, Absolute maximum rating = 36 V

TI Burr-Brown OPA227PA (DIP-8) (Digi-Key, Newark)
WIDE SUPPLY RANGE = ±2.5V to ±18V, Absolute maximum rating = +-18 V

TI Burr-Brown OPA228PA (DIP-8) (Digi-Key, Newark)
WIDE SUPPLY RANGE = ±2.5V to ±18V, Absolute maximum rating = +-18 V

TI Burr-Brown OPA604AP (DIP-8) (Digi-Key, Newark)
WIDE SUPPLY RANGE = ±4.5 to ±24V, Absolute maximum rating = +-25V

Texas Instruments THS4631D (SOIC-8) (Digi-Key, Newark)
Wide Supply Range: ± 5 V to ± 15 V, Absolute maximum rating = 33 V

[amb]

±18V = 36V

[gumleguf]

Cool. Later I discovered that the opamp's maximum PSU voltage was already documented on the "power supply" page. Sigh...

It's very kind of you to assist me with my questions. It helps give me confidence that I'll actually be able to succeed with the build. I appreciate it a lot!

In the documentation it says:

Notes about C7:

The circuit board has holes for up to six 18mm C7 capacitors or nine 12.5mm capacitors. They are not intended to be all filled with large value capacitors. The total capacitance should not exceed around 3000µF. If you use only three capacitors, install one adjacent to each amplifier block.

There is no benefit in using more capacitance than recommended. The reason for providing so many capacitor positions is to accommodate different physical capacitor sizes, and allow for paralleling many smaller-value capacitors to achieve the desired total capacitance. Some "boutique-grade" capacitors have large body dimensions for the amount of capacitance in each unit.

I noticed in the gallery that in some of the amps not all capacitors were fitted. Would there be a reason to downsize and only fit e.g. six of the nine 330µF 50V C7 capacitors like in steinchen's build?:

[amb]

I noticed in the gallery that in some of the amps not all capacitors were fitted. Would there be a reason to downsize and only fit e.g. six of the nine 330µF 50V C7 capacitors like in steinchen's build?:

http://www.amb.org/audio/mmm/gallery/steinchen/steinchen5.jpg

I can't quite tell if the caps steinchen used are really 330uF, maybe he used 470uFx6 which would bring the total capacitance close to 3000uF, not far from 330uFx9. Regardless, even 330uFx6 is "enough" capacitance. I think steinchen wanted to use the extra pads to install more film bypass caps, but there are already four of them.

[fishski13]

for what it's worth, the M3 makes for an outstanding pairing with the DT990/600. get a well ventilated chassis that can accommodate a higher quiescent current bias and/or taller heatsinks. the AD843 is a "well rounded" and cheap opamp choice.

[gumleguf]

Thanks for the input. I'm 99% settled on building the M3 and S11. Working with Jeff from http://www.glassjaraudio.com about complete kits for both. I will place the amp and PSU in seperate well ventilated enclosures. I have also upgraded the heatsinks to 2" types. I'll try to get my hands on the AD843 then.

Question:

I'm trying to find some power input jacks for the connection between the PSU and the amp that are more "solidly built" than the one shown on e.g. steinchen's amp here (no offense!):



I looked at the Neutrik PowerCon series but that might just be a bit overkill.

Does anyone know of a solution that's somewhere in between?

[xt0rted]

I used 2 Hammond 1455T2201 enclosures for my setup and also used the PowerCon connectors. They do seem a bit overkill but I like that they can't come undone while in use.

[fishski13]

my M3 had what has to be the worst plug/jack combo, ever. same suckage with similar results in my B1. http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=SC1214-ND. i finally ripped it out and replaced with a 4 pin-XLR last night.

[brucethehoon]

I'm right in the middle of my M3/s11 build. Got quite a bit done last night. Two things I'd say:
1. Soldering the op amps to those brown dog adapters was wicked. Now that I've done it a few times, I can say it's not too bad. Easy to make mistakes though! Jeff from Glass Jar DOES offer an opamp soldering service. I think $5 each. I would go this route if you've never done surface mount before.

2. I have the powercons and will be making the cable soon. If you want any impressions, I can make them today and post some photos of the process. At first glance it appears that the diameter of the hole in the back is quite a bit larger than the largest cable I might use. Neutrik sells a rubber/plastic sleeve that's intended to cover that gap. If you order today, make sure to throw a few of those in.

[gumleguf]

xt0rted > The 1455T2201 measures 8.66" x 6.50" x 2.03" and I plan to make an enclosure that's just a little bit larger than that in all directions. So I guess the PowerCon's would fit my enclosures nicely too.

fishski13 > I'll steer clear of those. I take it the 4 pin-XLR works much better?

brucethehoon > Cool!

1. I have an experienced family member to help me with the soldering. Hope that will work out fine.

2. Yes please, I'd love to see pictures of the cable with the PowerCon plugs, as well as the back of the M3/S11.