AMB Laboratories DIY Audio

[mcfrede]

I have recently started looking at the Beta22, but parts selection is a tough nut to crack.
I was hoping for a PCB-only order from AMB (sorry) and buying the rest from Mouser.
It does seem, however, that some parts have been discontinued and are no longer available and no substitutes have been listed.
My main reason behind this approach is that danish customs will "rip me a new one" on goods purchased outside the EU so in order to contain the financial impact I had hoped to be able to purchase most parts from Mouser.
Would I be able to find substitutes for those obsoleted parts or is it just so that nothing stepped in to take their place?
How will I be able to find replacement parts in the future if one such component dies on me?

[amb]

What parts are you having difficulties with?

Hint: unless you specify shipping insurance, shipments from AMB audio shop rarely cause import duties.

[mcfrede]

OK, sorry to drag this on, but I have experienced just how "anal" the danish customs can be about these kind of things (sorry for my constant "hiney-references").
They will retain your package and send you a letter telling you to declare the value of the package and document it with some kind of proof of purchase (receipt, payment transfer details etc.).
A purchase with a value (including shipment) of more than 16$ will be retained unless you are lucky enough to get through "under the radar" (I haven't in some time now, probably since it is a profit-machine for them).
OK, enough of my petty problems, on to the more constructive part.

D1, D2, D5-D10
The Fairchild BZX55C12 is no longer available, I found only one alternative but the parts list tells me to "not substitute with other types". I hope I am misinterpreting here and that my alternative will do the job fine, but I would like some reassurance.

Q1, Q2: N-channel small signal JFET 2SK170BL (TO-92)
These can be found on eBay, but am I risking buying counterfeit parts?
I actually found a German seller listing these still.
Mouser has seems to have a BLF variant, but will it do?

Q3, Q4: P-channel small signal JFET 2SJ74BL (TO-92)
These are also readily available on eBay, but same concerns as above...
Reichelt lists these as well, but they do not specify if it is the BL version, I will ask them.
For this one, Mouser tries to offer me that same 2SK170BLF as above...

Q5, Q6, Q11, Q12, Q15, Q16, Q17, Q25: NPN small signal BJT BC550C (TO-92)
Mouser has the BC550CG flavor on stock, data sheet is for the BC550C though so I reckon I will be safe buying these?

Q7, Q8, Q9, Q10, Q13, Q14, Q18, Q26: PNP small signal BJT BC560C (TO-92)
Jackpot! Mouser has these, admittedly they ARE scheduled for obsolescence and will be discontinued. An alternative could be the BC560CG variant from ON Semiconductor, would it be better to go this way to stick to the same manufacturer?

Q19, Q20: N-channel small signal JFET PN4392 (TO-92)
Available from Mouser, will be discontinued though, so I might stock up!

Q21, Q23: N-channel power MOSFET International Rectifier IRFZ24N (TO-220AB)
I suppose Mouser also have these on stock (IRFZ24NPBF).

Q22, Q24: P-channel power MOSFET International Rectifier IRF9Z34N (TO-220AB)
Mouser suggests IRF9Z34NPBF.

Hmm, I guess that when putting a little effort into this many of those components ARE actually available from Mouser unless I am mistaken. Thing is, when I am told to look for "IRFZ24N" and Mouser only lists "IRFZ24NPBF" I am thrown into a panic fit, since I would just HATE ordering the wrong parts and blow something up (even just having to re-order would drive me crazy).

Oh, and why is a electronical illiterate like me taking on a project like this you might think. Well, to prove that even slow-pokes like myself can get away with making the allegedly awsomnest of headamps. Hmm, and because I asked around on a danish head-fi forum what project I should take on next. Plan is to do a writeup on the project as I did when I made the Panda Headamp as I have gotten some feedback that it encouraged people to take on the project themselves and since apparently it helped some builders that were stuck.

[amb]

All the parts you list are available from AMB audio shop. You avoid all the headache to get them at the same time as the boards. I stock all these parts precisely to take care of situations like yours.

By the way, the PBF suffix denotes lead-free (a RoHS regulation compliance requirement), when the manufacturer's supply chain still may have non-compliant parts in stock. They are functionally equivalent. Make sure you get the ones with the N suffix, though. It's the 5th generation MOSFET specified for this design. Without the N, you get the 3rd generation version which is different.

The vishay version of BZX55C12 and On-Semi's BC550C and BC560C are fine.

The 2SK170BL and 2SJ74BL must be matched quads. You cannot buy just a few or even a handful and expect to find good matches. I offer matching service from a large quantity to solve that problem.

[mcfrede]

OK, so I am taking strides to make progress...
I am now convinced that buying matched pairs of the 2SK170BL and 2SJ74BL is the way to go.
Going through the AMB shop I found:

Fairchild PN4392 N-channel JFET (TO-92), tested pair for β22 output cascode
What lies in the "tested pair", that they are matched or that they are functional?

[amb]

It just means that they've been measured to reject obviously out of spec parts. No "matching" is done like that for the 2SK170BL/2SJ74BL. The PN4392s do not require close matching in the β22.

[mcfrede]

Regarding the resistors for the LED's: How important is it that I match the resistor value to the specific LED?
In other words... Can I just use the 10kOhm for most standard-issue LED's?
...As there is 100.000+ to choose from and I am likely to buy several colors and just go with whatever I fancy on the day I will be soldering.

[amb]

Most of the time you could use the default resistor value. For the σ11 or σ22 boards, the LED resistor value may need to be changed if your desired output voltage is far off from the default.

[Heffa]

My main reason behind this approach is that danish customs will "rip me a new one" on goods purchased outside the EU so in order to contain the financial impact I had hoped to be able to purchase most parts from Mouser.

You do know that you will still have to pay import taxes on stuff bought from Mouser, right?
Even though they have a web site in danish (or in my case swedish) don't mean that they ship from within the EU...
I had to add almost 25% to the final price on my last order. Never had to pay taxes/custom on stuff from AMB Shop though

//Håkan

[mcfrede]

You do know that you will still have to pay import taxes on stuff bought from Mouser, right?
Even though they have a web site in danish (or in my case swedish) don't mean that they ship from within the EU...
I had to add almost 25% to the final price on my last order. Never had to pay taxes/custom on stuff from AMB Shop though

//Håkan

Sorry to get back this late, the post escaped my attention somehow...

I am well aware that I will have to pay taxes on my orders at Mouser, I have done business with them several times. The advantages of doing business with Mouser are:
-Mouser will handle the paperwork.
-Mouser will NOT charge me 27+ USD for calculating import duty and taxes on my goods.
-Mouser will NOT delay my package for days (sometimes even weeks) whilst calculating import duty and taxes for my goods and REQUIRE of me that I show them a proof of purchase.

I my last order was shipped from somewhere in Texas and taxes etc. amounted to about 20% whereas (if going by normal mail) danish customs have added upwards of 30% to the price of my purchase.

The one way to try and get a package through without paying taxes/customs is having it sent as a gift and put a lower value on the package, effectively meaning that it would make no sense to have it insured and that if anything happens to my 200+ USD purchase I will simply have to bite the bullet and put in another order.

Now, I do not encourage others to source components for themselves since the AMB webshop is quite reasonable price-wise and since sourcing can be quite the "pain-in-the-arse". The paired/matched components are not feasible to source and others are hard to get so those too I ordered from AMB's webshop to support the great work.

Sorry if I am a bit "snappy", but I thought I had made it quite clear in previous posts why I opted to source some of the components myself. I am only happy for you if the swedish customs have not turned into the money-machine the danish customs have.

I hope we can put the "why-order-from-Mouser" talk behind us now and get back on track doing the fun stuff (you know, soldering, building etc.).