MemberDecember 14, 2021 at 3:52 pmPosted by: @trevor
Like the title says, I’m going to try and build my first set of speakers. My current set-up is basically nothing. I have been using a Jabra Soulmate Bluetooth speaker for almost 10 years and it’s time to upgrade.
This all started at Best Buy, I was going to snag a receiver and set of speakers for about $700. I hadn’t read any reviews or shopped around because anything would have been better than nothing. My phone is my only radio other than what’s in my truck. I thought having a stereo in the house would be fun as my kids are getting more into music (boy 11, girl 8). Anyway, back to Best Buy. I couldn’t close the deal on the set-up they had because it honestly sounded terrible. The speakers sounded like they were struggling to produce sounds that weren’t painful to listen to. There had to be a better way.
This began my internet search for “top bookshelf speakers”. Wow, big mistake. 400 YouTube video’s later, and I’m here.
My uneducated and misguided plan is the following:
Dayton Audio HTA100BT tube amplifier – Because I like the way it looks.
For the speakers:
That’s as far as I can go on my own. The rest I’m going to need a little help with, unless I’m already in trouble.
OK, to let you know, the top limit on that setup is approximately 97dB. If that is good for you… Also, you will be wiring it to 8 Ohm, and the manual of that amp only gives the 50W@4Ohm/channel rating. I haven’t checked if it is one that can play at higher ohms, but it being a tube amp, it may. But, at 8Ohm, that likely means 25W, and that is a low gain amount. Combined with a speaker with a sensitivity of 83dB and an RMS of 200W (so it can play an additional 23dB over the sensitivity if it has an amplifier that can drive it, meaning top continuous level of 106, before any other factors), and you can only get an additional 14dB at most (for reference, every multiple of 10 is an additional 10dB, so 10W = 10dB, 100W = 20dB, 1000W = 30dB; for doubling power, you get 3dB, so 2W = 3dB, 4W=6dB, 8W=9dB, 16W=12dB, 32W=15dB, 64W=18dB). All of those measures are at 1W/1M or 2.83V/1m (which is equivalent to 1W/1M under a very specific situation). So, 97dB at 3 feet, unless you are trying to be right up on the speaker, may be a bad choice.
This can be fixed through selection of a different, more sensitive, driver OR selecting a different AMP. I’d go with the latter as the THD+N rating on it is 0.5%, which is -46dB, meaning that if you are listening to the speaker at 97dB, the Total Harmonic Distortion is at 51dB. Will you hear that with the music? I cannot tell you for sure, but I can tell you I would feel better with the distortion at levels of 30dB and below. There is some masking with the music, but this is just giving you an idea of what will be going on with your selected speakers and amp.
20*Log(%/100) = dB
That is the equation to change THD+N values from percent into -dB. Source: https://benchmarkmedia.com/blogs/application_notes/interpreting-thd-measurements-think-db-not-percent
Now, you do not have to go overboard and get the THD+N below 0dB when playing at a loud volume. In fact, a noise floor needs considered. A quiet house without HVAC running, etc., is said to be in the mid-20dB range. And that is QUIET house. As soon as you add in HVAC, etc., you are talking a noise floor over 30dB. If the THD+N value is in that range (0.1% THD+N=-60dB, which compared to 97dB would put the noise level at 37dB, arguably able to blend into the ambient noise of a house without a problem, meaning that with music playing, you are not likely to hear it much, if at all; although we are in a range where if you look for it, you may very well hear it; also, the response along the frequency range varies, and the values are often given for an average or at 1kHz frequency being played at different wattage through the amplifier, meaning that higher frequencies may have even higher THD+N values than those seen on the 1kHz test, and thereby may cause hiss or other issues being audible in your tweeter), then you may be fine.
So, it is finding the balance. Also, there are studies that suggest people do not rate distortion highly as a reason they do not like a speaker, so concerns regarding distortion may be overblown. Have to add that as a caveat. But, I did want to explain more about how your selection of components will likely interact.