Part Lists and Suggestions

While reading through these parts lists, you may find it handy to have a copy of the schematic to refer to. (PDF, 4 KB)

Of the US distributors, Digi-Key is probably the best for people outside the US to use. Other distributors those outside the US might investigate are Farnell and Conrad. Farnell is actually part of the same company as Newark, but their part numbers aren’t unified, and they don’t carry all the same parts.

You’ll probably end up getting the op-amps from Digi-Key or RS Components. If you didn’t want to order from these distributors but wanted to put together a complete amp with parts from just one source, you’ll probably have to choose an op-amp other than the ones I recommend below. I don’t recommend that a beginner use anything but the OPA13x series op-amps, because they’re simply the most forgiving op-amps that also sound good.

The best path will require ordering from multiple sources. Unless you want to build an amp in a day including the time to get the parts, there’s little reason to get Radio Shack parts; the big mail-order houses have everything Radio Shack has and more, for cheaper, with better quality. I highly suggest you mail order everything you can, if you can stand waiting a week for the parts to arrive. The one exception is the protoboard: most of the mail-order houses only carry the expensive stuff designed to handle repeated soldering and desoldering. Since you’ll be building the amp once and probably then leaving it alone, you might as well use the cheap protoboard from Radio Shack or RS Components.

Some components are marked “Alt.” These are alternatives for the immediately preceding component.

For superior resistors that are easily distinguished from the generics, see the Precision Resistors section, below.

Description	Qty	ID	RadioShack	Digi-Key	Newark	Mouser	RS Components
220 µF/35 V electrolytic capacitor, radial leads	2	C1	272-1029	P5552	18C4706	647-UVR1V221MPA	315-0726
Alt. 220 µF/25 V electrolytic cap	2	C1	–	P5541	18C4672	75-517D25V220-E3	365-4133
Alt. 220 µF/16 V electrolytic cap	2	C1	–	P5530	18C4617	–	365-4060
0.1 µF polypropylene film cap (large!)*	2	C2	–	P3104	89F3466	75-715P200V0.1	240-5384
Alt. 0.1 µF metallized polyester cap (smallish)	2	C2	272-1069	E1104	–	75-MKT1813410014	–
Alt. 0.1 µF metallized polyester cap (really small)	2	C2	–	3013PH	46F3685	505-MKS2.1/63/10	179-9880
10 KΩ 1/4 W metal film resistor	1	RLED	–	10.0KXBK	84N1687	271-10K-RC	148-736
4.7 KΩ 1/4 W metal film resistor	2	R1	–	4.75KXBK	50N2120	271-4.7K-RC	148-663
100 KΩ 1/4 W metal film resistor	2	R2	–	100KXBK	84N1685	271-100K-RC	148-972
1 KΩ 1/4 W metal film resistor, gain 11	2	R3	–	1.00KXBK	84N1712	271-1K-RC	148-506
Alt. gain resistor, 2.0 KΩ, gain 6	2	R3	–	2.00KXBK	84N1736	271-2K-RC	148-578
Alt. gain resistor, ~2.5 KΩ, gain 5	2	R3	–	2.49KXBK	92B9453	271-2.55K-RC	148-590
Alt. gain resistor, 3.3 KΩ, gain 4	2	R3	–	3.32KXBK	84N1757	271-3.3K-RC	148-629
Alt. gain resistor, ~4.7 KΩ, gain 3	2	R3	–	4.75KXBK	50N2120	271-4.7K-RC	148-663
Alt. gain resistor, 10 KΩ, gain 2	2	R3	–	10.0KXBK	84N1687	271-10K-RC	148-736
10 KΩ 1/4 W metal film resistor	2	R4	–	10.0KXBK	84N1687	271-10K-RC	148-736
Alt. 1/4 W metal film resistor assortment	1	R1-R5	271-0309	–	–	–	–
Dual op-amp OPA2132PA	1	OPA	–	OPA2132PA	–	595-OPA2132PA	218-8281
Alt. dual op-amp OPA2132P	1	OPA	–	OPA2132P	35C1844	595-OPA2132PA	–
Alt. dual op-amp: OPA2134PA	1	OPA	–	OPA2134PA	–	595-OPA2134PA	285-8069
Power indicator LED, red diffused, 3mm	1	D1	276-026	160-1708	90F5862	859-LTL-1CHE	588-386
Alt. power LED, amber/yellow	1	D1	–	160-1709	96F2333	859-LTL-1CHY	588-392
Alt. power LED, green	1	D1	–	160-1710	87F393	859-LTL-1CHG	589-014
Stereo mini jack (3.5mm)	2	IN/OUT	274-0246	CP1-3513	96F9608	502-35RAPC4BH3	476-328
Alt. input jacks (RCA; black, white and red)	2	IN	274-0346 –  –	CP-1412 CP-1414 CP-1413	84N1165 –  –	161-2003 161-1004 161-2002	476-586 –  476-592
Alt. output jack (1/4" stereo)	1	OUT	274-0312	SC1125	84N1155	16PJ509	449-348
Protoboard (recommended type)	1	BOARD	276-0150	–	–	–	–
Alt. protoboard (simple “stripboard”**)	1	BOARD	–	–	–	–	206-5841

The most popular brand for this is Vishay-Dale’s CMF (a.k.a. RN) series. Specifically, the RN55x-F (1%) type. (For full details on how to interpret these CMF values, see the CMF data sheet.) Vishay-Dale CMF resistors are more expensive than generics, but in the quantities needed for this amp, the additional cost is negligible.

The Vishay CMF line also has 0.1% resistors, but you do not need that level of precision for this amp. If you do anything to get more accuracy, it should be to use a good multimeter to hand-match your resistors to higher tolerances. That may provide some audible improvement to some ears, but realize that this is relative matching. The point of buying 0.1% resistors is that their absolute values are within 0.1% of nominal. There are very few places in audio where absolute value accuracy is important.

If you can’t get Vishays but still want to try premium resistors, RS Components offers the RC series from Welwyn. I’ve never heard a report about whether these are an improvement over generics, but the specs suggest they’re on par with Vishay-Dale’s CMF series. They’re physically a bit bigger since RS only offers the 1/4 W resistors, but the price is similar to 1/8 W 1% Vishays.

Herewith, part numbers for Vishay-Dale RN55C/D resistors in all the values given above:

Description	Newark 1%	Newark 0.1%	Mouser 1%	Mouser 0.1%
47 Ω	03F7910	50B2558	71-RN55D-F-47.5	71-RN55C-B-47
100 Ω	83F1209	83F1208	71-RN55D-F-100	–
1 KΩ	83F1211	83F1210	71-RN55D-F-1.0K	71-RN55C-B-1K
2 KΩ	83F1230	83F1229	71-RN55D-F-2.0K	71-RN55C-B-2K
2.5 KΩ	–	–	71-RN55D-F-2.55K	–
3.3 KΩ	83F1256	–	71-RN55D-F-3.32K	–
4.7 KΩ	83F1272	–	71-RN55D-F-4.75K	–
10 KΩ	03F9465	83F1213	71-RN55D-F-10K	71-RN55C-B-10K
100 KΩ	83F1502	83F1214	71-RN55D-F-100K	71-RN55C-B-100K

Since this assortment is the only way to get metal film resistors at Radio Shack, you will have to get a bit creative to avoid buying two packs of resistors if you want to make two amps. One way is to also get a 5-pack of 10 KΩ carbon film resistors (RS 271-1335) and use these for RLED. (The power LED’s current-limiter.) Metal film resistors are nicer than carbon ones, but for the LED resistor, their virtues don’t matter. Another way you can go is to use a different value for this resistor than the CMoy schematic calls for. See the section on tweaking the LED resistor for details.

In Canada, there’s a store called The Source by Circuit City that is basically the Canadian version of Radio Shack. Just search for part number “2760150” on their web site. (They don’t use the dash for some reason.) No problem there.

In the UK, Radio Shack used to operate under their Tandy brand until several years ago. Since then, a new company called T2 has emerged to sell much of what Tandy used to, including the patterned perfboard we use in this tutorial. They will ship to many other countries in the world.

In Australia, you can get this same board at Dick Smith Electronics. It’s part number 21-113.

In Japan and probably other areas of Southeast Asia, you can find part number ICB-86 by the Sunhayato company, which again is all but identical to the Radio Shack board we use here. There is an alternate version of the board, part number ICB-86G, which uses a higher-quality epoxy-fiberglass board, rather than the cheaper phenolic paper substrate.

If none of those options work for you, the best alternative I can give you is the D-4 prototyping board, designed by DH Labs and sold by the people who publish audioXpress Magazine. It’s a fiberglass board, not phenolic paper as with the Radio Shack board, so it’s more durable. It has 3-pad pairs down the edge, instead of 2-pad pairs like the Radio Shack board, so you can replace the M-jumpers with a simple jumper connecting the outer pads on the R4 and R5 rows. The dimensions are different, too. It should fit the width of a standard mint tin, but just barely.

Failing all that, you might look at part number 1172142 from Farnell. This is a much bigger board than the Radio Shack board, so it’ll have to be cut down. The pattern is even more different from the recommended one than the DH Labs board, but close enough that adapting my layout to fit it should be straightforward. It looks like you just need to substitute a few bus strip cuts for the M jumpers I use on the RS board.

If you must use a much different type of protoboard, I recommend against trying to use the same parts layout I came up with for the Radio Shack board. Instead, create a new layout tuned to that pattern. If your board has a very generic pattern, such as stripboard or pad-per-hole board, I’d probably just go with a point-to-point layout: all the connections are made direct from one part lead to another on the bottom side of the board, instead of going through copper foils on the board itself.

You can read more about different types of prototyping boards here.

I review many other op-amps in the companion article, Notes on Audio Op-Amps.

For general portable use, I like the Serpac H series cases. The H-65 (1.0 × 2.75 × 4.95 in.) has plenty of space inside for a CMoy circuit, and its rounded corners and slim body give it a sleek look. The overall impression is of a pocket cigarillo case; it slips into a pocket very nicely. The H-65-9V variant has a nice 9 V battery compartment: it holds onto the battery snugly, and the contacts are fixed into place instead of using a 9 V battery strap. There is a taller version called the H-67. While the 9 V version of the H-67 only holds one battery, the “AC” version has a battery door without a battery compartment behind it; you can stuff two 9 V batteries in there. You’ll have to add some padding and such to keep the batteries from rattling around inside the case if you go this route.

If you’re thinking of going with a much larger case but still want to be able to run from batteries, I recommend adding a Bulgin dual-9 V battery drawer to one of the larger cases (Mouser part #122-BX0026).