[nysulli]

mouser also carries the part, as listed on tangents parts list, i highly suggest ordering it just in case, its removed some mild oscilations in a few cases, mine for example went from 63ma to 54ma draw after adding c6 and the opamps are noicably cooler as a result

 

[splaz]

Location to the left...

Bit of a hassle ordering from the US just for those. Thanks for your help anyway.

Looks like I'll just go to Farnell for them.

That or I'll just settle for powering it off less. I was thinking of using 24V but the 25V specs are a tad worrying if you take into account possible problems like tolerances, slight variations or manufacturing flaw/error in the parts themselves, the fact the supply may not be exactly 24V and ripple. Even with drop accross the diode I'd rather not risk it. All the other parts I'm using are rated to 35V or higher anyway.

Also, just thought I'd cram another question in here. Seriously should be the last. For anyone that's done a PINT with 2x9V batteries. Would an electroylytic cap 20mm high fit ?

non-ninja edit: Would it fit in a mint tin... you know your standard penguin, altoids thing that I'll have fun trying to find over here ?

from what I've seen it should. But alot of things should but can't... so thought I'd ask.

 

[FallenAngel]

I built a PINT with 2x9V batteries in a Mints TIN and the cap I'm using is a 25V 1000uF ELNA Duorex II which is pretty huge, it's 16 x 25mm and it just barely fits.

 

[splaz]

wow. This ain't that big, a 10x20. Would be nice to trade that height for a bit of width but no such luck in RS's range of case sizes. But I should be able to make that fit if you can do that.

Okay now I'm sure I'm 100% sorted for parts. Now to break the news to my wallet that more purchases are coming.

 

[rjkdivin]

Quote:

Originally Posted by splaz Okay. Every single part except this one I have sorted. C6. Tangent says that it is not needed, sort of a 'just in case' part. Problem is I can't seem to easily find a 4.7 microfarad in 35V in the right package size. I can however fairly easily get a 2.2 microfarad in 35V rating. Thing is, does 2.2 still fulfil the purpose of the part ?

Try Mouser part no. 80-T491B475K025 from Tangents original parts list. It is 4.7uf in 25v SMD Tantalum. I'm going to start my Mini3ized Pint up without C6 to begin, but I have some on hand in case needed. I got 12 from Mouser about a month ago.

As to the 2.2uf as a replacement, I don't know for sure, but it seems pretty close in value.....AMB???

Robert

 

[rjkdivin]

I fired up my first Pint (Mini3ized) tonight and it sounds great.....very dynamic, and very quiet.

I got the following measurements: (no load and inputs not shorted)

Running at 9V:
Current - 63mA
IG to OG - .8mV
OG to OR - .09mV
OG to OL - .13mV
Temperature of U3 - 98 deg F
Temperature of U1 - 105 deg F

Running at 18V:
Current - 70.5mA
IG to OG - 1.8mV
OG to OR - .05mV
OG to OL - .09mV
Temperature of U3 - 106 deg F
Temperature of U1 - 113 deg F

Do these look okay?

Using an input source and HD-600 as load, the current and temperatures remain approximately constant at both voltages. So far I cannot hear any difference in sound quality as I vary my bench supply between 9V and 18V. I'm reluctant to try it up any higher as the Op-Amp at 18V - 113 deg F is feeling pretty warm.

At this current I'm not sure how long two 9v. 270mAh batteries would last...7hrs?... and I'm wondering if it might be good to swap the ground channel Op-Amp for a lower current model?
Robert

 

[MASantos]

You said your PINT is minified but you have instaled R4. In the minified configuration you must stack R4 and C3 together and place them http://www.apuresound.com/pint/files/mmm.pdfin the C3 position. Check here for more information about minified PINT .

Also, I believe that with one 9v battery you are drawing more current than you should. My pint draws 44mAh with one 9v.

QUOTE=rjkdivin]I fired up my first Pint (Mini3ized) tonight and it sounds great.....very dynamic, and very quiet.

I got the following measurements: (no load and inputs not shorted)

Running at 9V:
Current - 63mA
IG to OG - .8mV
OG to OR - .09mV
OG to OL - .13mV
Temperature of U3 - 98 deg F
Temperature of U1 - 105 deg F

[/QUOTE]

 

[rjkdivin]

Quote:

Originally Posted by MASantos You said your PINT is minified but you have instaled R4. In the minified configuration you must stack R4 and C3 together and place them the C3 position. Also, I believe that with one 9v battery you are drawing more current than you should. My pint draws 44mAh with one 9v.

Thanks MASantos....you are correct.....I forgot to remove R4 on the front of the board before I tested it. I do, in fact have R4 and C3 stacked at the C3 position per AMB's instructions.

 

[MASantos]

double post

 

[rjkdivin]

I removed the extra R4 on the front of the PCB. It did not change the current, offset, or temperature measurements in any significant way, but it did open up the sound perceptably....it still sounds very good. When I get to it, I will run an A-B comparison with an M3 and my Hornet.

My R4(s) are sized with R3 for gain 11. Would going to gain 6 reduce the current draw?

Robert

 

[amb]

Quote:

Originally Posted by rjkdivin As to the 2.2uf as a replacement, I don't know for sure, but it seems pretty close in value.....AMB???

The value is a bit ad hoc, so 2.2µF is probably ok.

Your current draw is a bit higher than I'm used to seeing, but not far off the mark. Higher voltage gain (R4 and R3 values) should buy you a bit more margin of stability for L/R channels, but it wouldn't make much difference at the ground channel where the gain is 1.

 

[rjkdivin]

Quote:

Originally Posted by amb Your current draw is a bit higher than I'm used to seeing, but not far off the mark. Higher voltage gain (R4 and R3 values) should buy you a bit more margin of stability for L/R channels, but it wouldn't make much difference at the ground channel where the gain is 1.

I now have two Minified Pints up and running....one at a gain of 6, and one at 11. They both seem to be quite stable using my HD-600s and at voltages between 9v and 18v from my bench supply. I've switched both to the LM6172 for the ground channel opamp and kept the AD8397 for left and right. The temperature of the opamps climbs about 3 or 4 deg F. when going from 9v up to 18v., but still reasonable at about 104 deg max.

Using gain 6 gives the pot a slightly more usable range.

Changing to the LM6172 on the ground channel dropped the idle current dramatically down to about 30mA, which now seems a bit low....is this normal....or close to it?
Robert

 

[tangent]

Quote:

Originally Posted by rjkdivin Changing to the LM6172 on the ground channel dropped the idle current dramatically down to about 30mA, which now seems a bit low....is this normal....or close to it?

Seems reasonable to me. Around 25 mA for the 8397, and around 5 mA for the 6172. Both are temperature and supply voltage dependent, so study the datasheets carefully if you want a more exact answer.

 

[rjkdivin]

Quote:

Originally Posted by tangent Seems reasonable to me. Around 25 mA for the 8397, and around 5 mA for the 6172. Both are temperature and supply voltage dependent, so study the datasheets carefully if you want a more exact answer.

Thanks Tangent!....have you given any more thought to selling these boards again? I'd really like to build one more.
Robert