Stupid M3 questions which I'm sure have been answered before...

[n_maher]

I find it hard to believe that you're an EE asking that question.

[geremy]

I graduated from Georgia Tech with a BSEE in 1999.

I don't actually believe that it makes a difference, but I'll be the first to admit I don't know everything.

Besides, I do mostly digital stuff...

[Mister X]

I have plenty of standard eutectic solder, but I'm wondering if I the Cardas solder (or equivalent) would represent a significant improvement.

The Cardas quad eutectic solder is a little easier to work with and I kinda like the way it smells but I would not suggest there is a notable sonic difference between it and random eutectic solder.

[Mister X]

I almost forgot.

DIY club offers a couple of different volume control kits as well.
Here is the link------->

DIYCLUB

You can find a lot of the same stuff on Ebay
Here is a random example:
Hi-End Volume Control DIY Kit,LED, Remote Control /V-02 - eBay (item 250349671795 end time Jun-27-09 20:43:25 PDT)

And...
It may be a good idea to pick some op-amps that are a better synergy match for your headphones?
(bright op-amps with bright headphones = an unpleasant experience!)

[geremy]

I like bright. I'm not opposed to rolling but I like the really tight dynamics.

Thanks for the link. I already ordered a volume control/remote/input selector kit from bbp at diyaudio. The same one that is in naamanf's b22. Quite inexpensive and only 1 left so I pulled the trigger. It's not that big a deal if it's a bust. I have to say, I have been shopping for a headphone amp for a while, and they DIY route is amazing in the feature/dollar ratio!

naamanf's b22: DIY amp and such build gallery

thread about kit: diyAudio Forums - New project : R-2R Attenuator With Remote Control V2 - Page 1

I will have to do something else about gain control. At the moment I'm thinking i will have to open the top cover to change the gain, which isn't that bad.

I have also decided to start with a gain of 5. I know some folks recommend 2, but I have to think that has a lot to do with the source as well.

Thanks for all the help! My summer intern is eager to get building. ;-) The vast majority of the parts will be here next week.

The only things really left to purchase now are the case, transformer for the sigma-11 and a 5V supply for the volume/input selector kit.

I am toying with the idea of peak-meters. Maybe ones that can be switched in and out of the signal path.

[n_maher]

The Cardas quad eutectic solder is a little easier to work with <snip>

I would agree with this, it's my solder of choice purely for workability reasons.

[guzziguy]

I hear that it sounds moar killer when sprinkled with JMFD (Jena Magic Fairy Dust), which is made from a propriety combination of ground Unicorn horn and Dragon's teeth.

On a serious note, how does the Cardas Tri-eutectic solder compare with the quad for ease of use? I'd prefer to delete the lead.

[luvdunhill]

On a serious note, how does the Cardas Tri-eutectic solder compare with the quad for ease of use? I'd prefer to delete the lead.

Lead better

[geremy]

Almost all the parts are now in and I have some more silly questions:

1) I plan to mount the board in the chassis backwards (volume and bass-boost pots to the rear) to minimize the length of wire from the input selector/volume attenuator kit and also to place the heat sinks closer to the edge of the case where the venting is. This means that I will be using the front board inputs only. When looking at the board, this means that I have about 6" of copper trace antennas on each signal channel. Is there any recommended termination schema? Should I cut the traces to the rear (my front) inputs?

2) For C4, C5 and C7 I ordered from the Nichicon PW line. Do these caps make much of an impact on sound being that they are not in the direct signal path? Should I upgrade these to the KZ or go for some boutique brand? I don't see how they are going to make any difference but I figured I'd ask the experts.

Thanks for the help.

[Mister X]

From Mouser:

9 X 647-UKZ1E221MHM = $3.42
7 X 647-UKZ1E101MPM = $2.38

9 X 647-UPW1H331MPD = $5.85
7 X 647-UPW1H331MPD = $2.52

Being able to say your M3 has boutique caps that were cheaper then the standard caps = priceless.
the UKZ caps are only rated at 25 volts instead of 50 volts for the UPWs which after the diode drop should not be an issue with a Q11 configured to output 24 volts. Sound wise I dunno if there is enough difference to warrant the added $, especially since you already have the UPWs.

[geremy]

Actually according the nichicon website there is UKZ1H caps available, rated at 50V. I cannot find them on the mouser site thought. The do have a slimmer temperature range (-40 to 85 C) and are only rated for 1000 hours as opposed to the PW's 3000 hours.

Thanks though, I didn't believe that there would be any appreciable difference but I wanted to check.

Now I need to find a small +5V linear standby supply for the volume/input kit. I'm thinking about going with the standby supply which Mister X linked me to earlier in the thread here: Standby supplies

[Beefy]

Anything MisterX recommends is a safe bet.

Though I would personally stick with higher voltage rated UPW (or UHE) caps throughout the amp.

[luvdunhill]

Now I need to find a small +5V linear standby supply for the volume/input kit. I'm thinking about going with the standby supply which Mister X linked me to earlier in the thread here: Standby supplies

This is the prefect chance to do a little perf board project.

[geremy]

Nobody has any thoughts about terminating the 6 inches of copper trace from the unused inputs? Is the question just silly?

[geremy]

I have attached my projected faceplate design. Inputs are appreciated! I'm not sure whether or not it is OK to use the AMB Laboratories name. Anybody know?

Current Plan is for the case to be the Hifi2000 Galaxy GX348 with the optional 10mm front panel. The text is (hopefully) milled out from the plate. The knobs are also from modushop.biz, they are the 29mm for source/power and 39mm for volume/mute. The jacks are standard neutrik. I am considering adding the milled handles if that is possible on the galaxy front panel but I'm worried it may be overdoing it.

[Pars]

Nobody has any thoughts about terminating the 6 inches of copper trace from the unused inputs? Is the question just silly?

Cut them if you are concerned with them... couldn't hurt (unless you need to reuse the board later).

I have attached my projected faceplate design. Inputs are appreciated! I'm not sure whether or not it is OK to use the AMB Laboratories name. Anybody know?

Current Plan is for the case to be the Hifi2000 Galaxy GX348 with the optional 10mm front panel. The text is (hopefully) milled out from the plate. The knobs are also from modushop.biz, they are the 29mm for source/power and 39mm for volume/mute. The jacks are standard neutrik. I am considering adding the milled handles if that is possible on the galaxy front panel but I'm worried it may be overdoing it.

Front looks ok, no real comments. You might PM amb to see if it is ok using Amb Labs. Not quite sure what you mean by the text being milled out from the plate? As in cutting away material to leave raised text? I would think the rack handles might be a bit much as this isn't a big power amp. That's just me though.

[Bidoux]

Since here is for stupid questions, I hope you don't mind I ask some.

- Is the input voltage symetrical ? is it ±27V (seems to be a lot) or +27V and ground ?
-According to the schematics, the mosfet output stage is not powered with the op-amp power, is it a problem to power them with Vop± ? (like in the original SDS labs)
- For all the Jfets used, AMB draw them with a dot. Is it for the Drain or for the source ?
-If I do not want the the bass boost, do I just shorcut everything like Sbll do ?

[n_maher]

- Is the input voltage symetrical ? is it 27V (seems to be a lot) or +27V and ground ?

It's a single supply (27V/G) and split on the board by the TLE voltage divider.

-If I do not want the the bass boost, do I just shorcut everything like Sbll do ?

RTFM, the instructions for what to do if you do not want bass boost are right on amb's website.

For your other 2 questions I have no idea what you're asking.

[Bidoux]

Sorry for that.
I'm asking if the mosfets are powered the same as the op-amp like here.
I understood how the BB works.

[Beefy]

Sorry for that.
I'm asking if the mosfets are powered the same as the op-amp like here.
I understood how the BB works.

For the MMM, the is no reason to use any other resource than AMB's site. Everything is detailed there as clear as day.

The power to the OPAMPs is heavily isolated from the MOSFETs - that is the whole point of AMB's design.