Project FAQ
I’ve never built a headphone amp before. Can I build a PPA?
The PPA is not a good choice for your first DIY amp project. You may succeed without any problems, but if it doesn’t work at first, you’ll be totally lost. The parts for a PPA are expensive enough that you’ll want to be reasonably confident that you can troubleshoot the amp if it doesn’t work when you turn it on for the first time.
I recommend that new DIYers first read my article Getting Started in Audio DIY, and then either build a CMoy Pocket Amp or a PIMETA to get some basic skills before proceeding to the PPA.
There’s an awful lot of stuff to read here. Do I have to read it all?
The more you read, the more likely you’ll build the amp correctly the first time.
At minimum you should read through the Part Selection Guide section. The first section of this page details all of the parts used on the amp. There are no parts kits available for this amplifier, so you need to read through this page to find out what parts will give the best results in this amplifier. There is no single “correct” set of parts, but there are infinite wrong choices you could make. This section will tell you what works and why. Each part description is written to put the most important information up front, with increasing detail for those who want to truly understand what is going on with that part. Thus, you may skim, but it is also true that if you do that and later ask a question about it, you may find that you get directed right back to the documentation.
You may also find the Part Lists page handy. This page lists almost everything you need to build a working PPA. You still need to read through the Part Selection Guide to learn how to choose among the alternatives given on that page. Also, you need other parts that cannot be listed on that page because they depend too much on your particular situation so I cannot recommend anything specific.
Once you’ve chosen your parts, you probably need to read the Step-by-Step Assembly Guide page to learn how to assemble those parts into a working amplifier. You may wish to skim these sections before choosing your parts, because the parts selection process will make more sense if you know how the parts will be used. If you are an experienced DIYer, you may be able to skip this section entirely.
Once the amp is working, you may wish to read through the Tweaks page to learn how to improve the amplifier.
I’m confused by the number of choices I have in choosing parts. Help!
If you don’t want to think about part values, just use the ones given in the schematic. These values will work for most purposes, but they may not be the best for your particular purpose. There is no substitute for knowledge and experience.
There are many “optional” parts. How do I know if I need them?
These correspond to optional features. Some of these features are just nice to have, and others provide functionality that you may or may not need. If you leave out all of the optional parts, the circuit should still function, but it won’t work as well as the board design allows. Read the documentation carefully to see why each feature exists before you decide whether to leave it out or not.
What’s the best way to save money on parts?
The biggest, least harmful step you can take is to use moderately-priced op-amps and a cheap enclosure.
If that doesn’t save enough money, start dropping optional parts.
Be careful about choosing cheaper parts than the ones recommended in the documentation. If you can’t get the cost of the amp down far enough, it would probably be better to go with a different amp design that’s inherently less costly than to use inferior parts for this high-end amp. Consider the PIMETA v2, for instance, a simpler PPA-like amp.
Can I use parts not mentioned in your parts list?
There are so many parts that will work that the parts list couldn’t possibly list them all; it’s really just a list of examples. If you’re an experienced amp builder, you can probably choose suitable parts without even consulting the parts list.
If you’re not so experienced, you may want to do some searching in the Head-Fi DIY forum archives. Someone else may have used the part you’re looking at and reported on it, or there may be advice there saying why a given part is a bad choice for a PPA. If you can’t find any information there, please ask on the forums about it. Often a part that looks like it will work, won’t.
I don’t want to chase down all these parts. Can I buy a kit?
Sorry, no one’s offering kits right now, and I have no plans to ever offer kits. I sell the hard-to-find parts along with the circuit boards. You may be able to get away with just one order to one of the major electronic parts distributors for the rest of the parts, but you will often need to make a few separate orders to get the best balance of parts. If for some reason you do not have access to a major parts distributor, you may be able to ask for someone to send you some parts; please don’t ask me, though, because I’m already offering everything I wish to on my ordering page.
Are there people who can build the amplifier for me?
If you’ve looked through the docs and have concluded that you’d really rather not build the amp yourself, you can look for a builder on the forums. There are several active builders.
Can I use the PPA as a preamp?
The PPA was designed with headphones in mind. Headphones are completely passive, with no connection to the input side of the amplifier, so we are able to split the ground circuit into two parts, to good effect.
If you were to use a stock PPA as a preamp, the cabling situation in typical source-preamp-amp configurations shorts out the ground channel. At best, this defeats it, making it a waste of parts. But worse, it can actually make the ground channel unstable, which is never good.
If you really wanted to do this, you could do any of several modifications to the circuit:
You could leave out the TLE2426es and ground channel parts, power the amp with a dual-voltage supply, and connect the ground leg of the supply to IG and OG.
Design your own PPA-like circuit with only one TLE2426 connected to the input of the ground channel, and with all ground connections run to what is OG now. The result would be much like the META42, but with a better power supply arrangement.
Use one of the simpler amps on this site. The CMoy, MINT and META42 will all work as preamps without modification.
I have a question. Who do I ask?
First, look through this documentation. I update it frequently, adding new information as I discover things that it doesn’t cover which it should, so the answer is often here if you look carefully enough.
Next, look through my articles list. I’ve written quite a few of these articles now, one of which may answer your question. Naturally I don’t wish to repeat myself here in the PPA documentation, and sometimes I don’t point to a suitable article when I should.
If you can’t find it here, do a search in the Head-Fi DIY forum archives. Asking a question that’s been answered before (sometimes many times before) is a waste of the other forum members' time and yours. It’s quicker to search the archives than to post the question and wait for people to answer.
If the answer is not in the archives, go ahead and post the question to the forum. It’s better to post publically than ask people via email or private messaging because you get more answers by posting publically, and the answers are archived for future builders to find.
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