[White Mike]

Wow. Thats getting pretty close to a complete summary of the entire thread so far!

 

[GregVDS]

Ok,

many thanks AMB for this so complete answer. I will use that, for sure.

For the input DC offset, I measured my iPod, the headphone output is somewhere around 0.1mV, and the line output is around 0.3mV. These do not move when on internal battery, and fluctuate from 0.2 to 0.4 for the line output when on wall charger. If this is passed through a voltage gain of 5, to a Grado, the headphone will have 1 to max 2 mV through 32ohms, meaning 0.03125 to max 0.0625 mA. Is this a real threat, for the headphone is expensive enough at least to burn them!

Ok, now if this is too much, I should put a cap inline with the input, now, before or after the Linkwitz pcb? And what kind, and what value? will it interact with the crossfeed or not (surely, but how to minimize this effect)?

One of my Cmoy (front buffered) have a Linkwitz high-Z implementation, and a gain of 4 to 5, I'm satified with the volume level, can I just assume I will have the same volume level if I stick to a gain of 5 in the M³?

How can I further fin-tune the M³ for Grado / OPA627, Gain 5, besides 27pF in place of 33pF, are there specific bias settings?

I want to achieve gain 5 without touching to the R4 (10kOhms), so I need r3 = 2500 Ohms, right? Is it the optimum, regarding current and noise, for 4kOhms and 1kohms work also, and a lot more combinations.

Many many thanks again, I want to study it and be sure I understand everything and be convinced I can cope with all the aspects before beginning this.

All the best,

Greg

 

[amb]

Quote:

Originally Posted by GregVDS For the input DC offset, I measured my iPod, the headphone output is somewhere around 0.1mV, and the line output is around 0.3mV.

This is low enough not to be a concern.

Quote:

One of my Cmoy (front buffered) have a Linkwitz high-Z implementation, and a gain of 4 to 5, I'm satified with the volume level, can I just assume I will have the same volume level if I stick to a gain of 5 in the M³?

Yes. Or, you could keep it at the standard gain of 11, which is only about 6 or 7dB more at max volume.

Quote:

How can I further fin-tune the M³ for Grado / OPA627, Gain 5, besides 27pF in place of 33pF, are there specific bias settings?

There are no other opamp-specific settings except power supply voltage. 24V is safe for any of the recommended opamps.

If you plan to try different opamps in the future then you should keep C1 at 33pF. The difference is small anyway, we're talking about frequency response up to 1.2MHz instead of 1.5MHz, which in either case is rather academic.

Quote:

I want to achieve gain 5 without touching to the R4 (10kOhms), so I need r3 = 2500 Ohms, right? Is it the optimum, regarding current and noise, for 4kOhms and 1kohms work also, and a lot more combinations.

10K/2.5K is fine, 4.02K/1K works too. The difference in noise is negligible. However the two require different value of Cbb to achieve similar bass boost control range (assuming 50K pot). Use the bass boost calculator on my site to figure this out.

 

[GregVDS]

Ok,

I come back to my question about orange drop capacitors. The overrated voltage is all what I found on Mouser. Could someone point me where to find 50V ones as seen on Tangentsoft's website? Are these ones the best, or Solen is better? I try to find very good ones for CBB and crossfeed (0.1 and 0.022µF) as these are in the signal path.

And also, if someone could point me also to small spacers, screws and stuff like that, I'm interested, is there a special section in Mouser for this?

I just ordered my M³ pcb, STEP and crossfeed PCB; as soon as I begin to build and solder things, I will post pictures of it.

Many thanks again for the advices and help.

All the best,

GregVDS

 

[funch]

I just got my orders in for my M3. I'm also using 200v Orange Drops in the Cbb position, as well as on Tangent's crossfeed board, and the fit is fine. Hope this helps.

 

[GregVDS]

Ok, thanks, I will so stick to these.

Logically, a too high voltage is just useless, but it should not be harmful for the sound, right?

I hope my pcbs will arrive quickly

I still don't have any answer from par-metal, are they closed at the moment, or they don't do business with european guys?

I want a custom 7.5'' depth x 9'' width x 2'' height aluminium 20-series case. I will in the future replace the front panel by front panel express one.

And by the way, what difference between Anodized and alodined aluminium?

Many thanks!

All the best,

GregVDS

 

[skyskraper]

the best bet with parmetals is to call them or email their ebay store linky another option for you may be one of the cases from thl, they at least reply to their emails quickly

 

[amb]

Quote:

Originally Posted by GregVDS Logically, a too high voltage is just useless, but it should not be harmful for the sound, right?

It should have no adverse effect on the sound.

Quote:

I still don't have any answer from par-metal, are they closed at the moment, or they don't do business with european guys?

They don't seem to answer emails. You should contact them by telephone (keeping in mind the timezone differences). The telephone number is listed on their web site. I don't know whether they will ship outside of the US, so be sure to ask.

Update: skyskraper's link to Par-Metal's ebay store "Antek" is the Australian version. Here is the general one. They items offered through the ebay store can be shipped to Europe.

 

[tess]

if its any use to GregVDS I've just phoned Par-Metal after many unanswered emails and they don't deliver to the UK.

Have a look at these cases, http://www.hifi2000.it/default.asp?id=16&mnu=16

they are available from http://www.audiokit.it/ but are on Italian Hol's until the end of the month.

 

[amb]

Quote:

Originally Posted by tess Have a look at these cases, http://www.hifi2000.it/default.asp?id=16&mnu=16

These look nice, but have an internal height of only 40mm, which is a bit too short for the board with 1.5" heat sinks and standoffs. They offer taller versions but the next step up is 80mm, making it less sleek-looking.

 

[GregVDS]

Thank you for all these answers.

These boxes from Italy look beautiful and very well finished, better than Par Metal in my opinion, and cost less! But you're right AMB, those 4 cm are very small, but they could go out of the box like lamps. It's just an idea, maybe mad. Surely not the safest way to go. if that darn box could be 5 to 6 cm height and not 4... Sigh

I still don't find the right enclosure, this is difficult and frustrating, for I cannot build one by myself, lacking the tools.

Ok, C4, C5, C8 for the M³ and D1 for the STEP seem to be out of stock. How long can it takes?

I ordered also Ag solder from WBT, I know this is a little bit too much, but I want to do this the best I can. Input will go through WBT-0201 RCA sockets.

All the best to all of you

GregVDS

ps: so there are very few chances Par-Metal will ship to Belgium, I guess...

 

[Jazper]

Quote:

Originally Posted by GregVDS Ok, C4, C5, C8 for the M³ and D1 for the STEP seem to be out of stock. How long can it takes?

for C8 you could use mouser part no: 505-MKP20.1/100/5

As for C4 and C5 you could use mouser part no: 647-UHE1H101MPD

and for the steps D1 you can use mouser part number: 512-RHRP860

These shouldn't change the sonic characteristics much from the stock parts

all are currently in stock at mouser

 

[GregVDS]

Ok,

Many thanks all!

Tess, these are the most neat and clean box I've seen yet on internet. For sure, as AMB pointed out, the 4cm height is not enough, and the 8cm is too much.

But I have this idea:

the galaxy boxes are simply extruded profiles of 4cm height, on wich the front and back panels are attached (4 hex recessed screws each), and on which also the top and bottom plates are attached (4 hex recessed screws each). I think it is quite simple to have whatever width and depth. For height, could it be possible to cut one of the profiles along its longest axis, in order to achieve let's say a height of 5.5cm (enough clearance for the 1.5'' heatsink and under the pcb, still achieving the centering of the knobs vertically on the front face).

I asked www.hifi2000.it for this, and still don't have an answer. I'm afraid all the site being written in italian, maybe the guys are not familiar with english?

I plan to replace all the top, bottom, back and front by front panel express ones.

I need, to plan this, to know the exact dimensions of the STEP v1.2 and the crossfeed pcbs and holes in them. The info is not complete regarding this on Tangentsoft's site. If someone can just measure it and write me down the quotes, I would be very pleased. I presume the quotes given by AMB for the M³ are exact, right?

Anybody use the www.diycable.com aluminium knobs and remote control volume pcb?


Ok, hope parts will begin to arrive soon

All the best,

Greg

 

[Nisbeth]

Quote:

Originally Posted by GregVDS Ok, the galaxy boxes are simply extruded profiles of 4cm height, on wich the front and back panels are attached (4 hex recessed screws each), and on which also the top and bottom plates are attached (4 hex recessed screws each). I think it is quite simple to have whatever width and depth. For height, could it be possible to cut one of the profiles along its longest axis, in order to achieve let's say a height of 5.5cm (enough clearance for the 1.5'' heatsink and under the pcb, still achieving the centering of the knobs vertically on the front face).

Cutting the profile isn't going to work, as you can't get the case back together again. I can send you some pics to show you what you're up against

Replacing the top/bottom (which is steel) and/or the front/rear (which is aluminium) is easy though.

Quote:

Originally Posted by GregVDS I asked www.hifi2000.it for this, and still don't have an answer. I'm afraid all the site being written in italian, maybe the guys are not familiar with english?

The will reply in english, but they can be a little slow to respond and beside most of southern europe is closed for holidays in august. Be patient

Quote:

Originally Posted by GregVDS Anybody use the www.diycable.com aluminium knobs and remote control volume pcb?

While you're at audiokit.it, check out their selection of knobs as well

You can order the volume control PCB that diycable.com sells directly from the designer at electronics.dantimax.dk

/U.

 

[amb]

Quote:

Originally Posted by GregVDS I plan to replace all the top, bottom, back and front by front panel express ones.

If you're going to be doing that, then you might as well make your own custom enclosure.

Quote:

I presume the quotes given by AMB for the M³ are exact, right?

The measuerments stated on the M³ pcb dimensional drawing (found in the "Circuit board" section of my M³ site) are exact. You should also be able to get an actual-size printout of the PDF version of the silkscreen layer picture, also on that same webpage.