[miketriple]

following the directions of http://tangentsoft.net/audio/mint/, i'm going to start my first project soon. i was going to make the old cmoy design, but this one stuck out more to me. however, i'm having trouble with the resistors, probably because it wasn't spelled out with digi-key order #s like the rest were, heh heh.

the schematics show a need for some 470 kohm resistors, but digi-key doesn't seem to have those, only 475 kohm. is that fine? i'd like to order from the same place to save shipping, since over $25 gives free shipping from digi-key

also, while looking for a 220 ohm resistor, i've come to another problem. searching through digi-key's products gave me a choice between metal film resistors: cut tape, tape and box, tape and reel, and power: .25, .4, .6W? which is it that i need?

thank you! i can't wait to get this stuff ordered.

 

[Wyloch]

Well, I do all my shopping at radio shack (except for the op-amp and the potentiometer) and am very satisfied, but if you wanna use DigiKey, go for it. I can't necessarily help you with their part numbers, but I thought I'd clear some things up.

The schematics do not show a need for 470 kohm resistors. They're 4.7 kohm. Big difference. And no, the difference between 4.7kohm and 4.75 kohm is negligible for this project. So, don't get 470kohm resistors.

Also, you don't want a 220 ohm resistor. You want a 220 uF CAPACITOR. Specifically, you want an electrolytic capacitor rated at or around 35V and with radial leads (not axial). Two of them.

The other two capacitors in the project, which actually aren't necessary at all, are .1uF metal film capacitors.

 

[tcristy]

Quote:

the schematics show a need for some 470 kohm resistors, but digi-key doesn't seem to have those,

Sure they do:
P470KCACT-ND Panasonic 1/4W 1% metal film, 470kohm

 

[Wyloch]

But again, if you're following Tangent's guide, you do not want 470kohm. You want 4.7kohm.

 

[tcristy]

Wyloch,

I think you may be confused by the thread title mentioning CMOY but the post is actually about building a Mint. The Mint schematic on Tangents site most certainly shows 470kOhm R2 and R6 and a 220 ohm R2:
http://tangentsoft.net/audio/mint/misc/schematic.pdf

 

[miketriple]

ah yes, sorry.. i'm building a MINT not the cmoy!

what about the tape box reel stuff?

 

[tcristy]

Those are different ways bulk resistors are packaged for factory use. I normally get cut tape.

 

[miketriple]

thanks! i'll go cut for all of them

panasonic vs yageo.. does it matter?

also.. the schematic jumps from r8 to r11, and r11's value is not supplied. any idea what it is?

[nevermind about r11.. i missed that part on the part selection guide

]

 

[skyskraper]

dude you should check out tangents part selection guide, it'll help answer, or give you a push in the right direction with your questions

he talks about r11 in there and selecting the right value

 

[Daroid]

"R11
This resistor is for modifying the bandwidth of the buffer, which can improve its sound audibly. The downside is that it consumes more current as bandwidth goes up. A practical maximum value for this resistor is about 4.7 KΩ. As the value drops, bandwidth goes up and so does power draw. You could jumper this position for maximum bandwidth, but since MINT amps are generally battery-powered, this probably isn't a good idea. I usually put somewhere between 220 Ω and 1 KΩ here. If you want maximum battery life, leave this position empty.

Note that this resistor position is smaller than the others. You need to use a standard size 1/8W resistor here to get it to fit."

- http://tangentsoft.net/audio/mint/pguide.html

Panasonic vs. Yageo - go for what is cheaper i'll say. Make sure that they fit on the board (length-wize)

EDIT: but usually with resistors; get resistors with a low tolerance rating 1% or thereabouts with a low temperature coefficient, metal-film or even metal glazed for signal path. Technically it would be better than the average 5% no-name metal film RadioShack resistor. Audible difference ? IMHO only marginally as long as you use metal film types.

 

[miketriple]

ahh yeah, sorry. you guys beat me by about 2 minutes there, lol. i just read it.

 

[miketriple]

did you all see the checklist on that site? in the diagram, i only see 1 R1, yet the checklist's quantity says 2? same with all of them, actually. the quantity is 2 while there aren't 2 on the schematic.

 

[Daroid]

Schematics usually only shows one channel. You'll need two of everything in that Schematic. Even the op-amp is mono

EDIT: Got that wrong: it uses an AD8620 op-amp in the schematic - only the AD8610 is mono

EDIT 2: Ok, final answer: the schematic show a single channel only - but with the dual op-amp.

The PSU design is as it should be and connects directly to the op-amp V+ and V-.

 

[tcristy]

I do not know how the prerformance compares, but I like the Panasonics because they are tiny. They are less than half the physical size of most other 1/4W resistors.

 

[miketriple]

so i DO need to double the schematic? the assembly pics look like that, yeah.

i'm buying packs of 10 of the resistors anyway