I've been refining a small 20W "practice" guitar amplifier, optimized for a small acoustic guitar that has been fitted with a single coil magnetic pickup. At this point the overall tone is more than satisfactory using a small full range speaker, but the high end could use a little boost. Magnetic pickups already do not favor the super high like piezo pickups do. So I'm trying to decide whether I'd do better with electronic boost of the highs, a tweeter, or maybe both.
The amplifier will be positioned around "desk level", and so I'd think a tweeter might offer better omni-directional coverage of the highs then an electronic solution alone, so I would like to experiment. But from a magnetic pickup, there may not be many "highs" to work with, and for reasons unknown to me tweeters are expensive... most are more expensive then my existing full range speaker. So I'm looking for some recommendations to test with that won't break the bank, and maybe some insight as to why these sometimes tiny speakers tend to be so costly.
NOTE: I've been informed the "amps and instruments" page would be a better place for this post, and I've done so... but I can't find an option to delete this one. The moderator may do so for me if possible?
The amplifier will be positioned around "desk level", and so I'd think a tweeter might offer better omni-directional coverage of the highs then an electronic solution alone, so I would like to experiment. But from a magnetic pickup, there may not be many "highs" to work with, and for reasons unknown to me tweeters are expensive... most are more expensive then my existing full range speaker. So I'm looking for some recommendations to test with that won't break the bank, and maybe some insight as to why these sometimes tiny speakers tend to be so costly.
NOTE: I've been informed the "amps and instruments" page would be a better place for this post, and I've done so... but I can't find an option to delete this one. The moderator may do so for me if possible?
Last edited:
You can just go with a good full range which will handle frequencies up to 18kHz no problem, some can hit 20kHz even. Looks like you are looking for low cost - check out Vifa TC9FD ($12), or Faital Pro 3FE22 ($28) or 3FE25 ($19).
If you want a bit more high end boost, there are economical $1 tweeters that sound quite good.
Speaker Stuff
Look for Apex Jr, and also polycarbonate tweeter for $1 or $2 are good. You will need a XO though - a simple cap high pass and coil for low pass but that will add to costs.
Another very good full range with 20kHz reach is Peerless P830986.
If you don't mind spending $20, I can highly recommend the Dayton DC28F-8 soft dome tweeter - super clear and transparent sound.
If you want a bit more high end boost, there are economical $1 tweeters that sound quite good.
Speaker Stuff
Look for Apex Jr, and also polycarbonate tweeter for $1 or $2 are good. You will need a XO though - a simple cap high pass and coil for low pass but that will add to costs.
Another very good full range with 20kHz reach is Peerless P830986.
If you don't mind spending $20, I can highly recommend the Dayton DC28F-8 soft dome tweeter - super clear and transparent sound.
Thanks! Tweeters for $1? I'll have to buy some of those just to play with! And yeah... I've used quite a few small Vifa speakers! Even their tiny ones like Vifa TC7FD00-04 are amazing.
As far as the more expensive tweeters like the Dayton, for this one such cost would be overkill. But maybe it wouldn't hurt to get at least one good reference tweeter to get a feel for the best I can hope for when making tests.
As far as the more expensive tweeters like the Dayton, for this one such cost would be overkill. But maybe it wouldn't hurt to get at least one good reference tweeter to get a feel for the best I can hope for when making tests.
I guess the lowpass is embedded...with the woofer itself !
.........
High fidelity tweeters as midbass & midranges are not made for instruments 🙄
When I worked at Fishman they used one or more soft dome (fabric) tweeters in their acoustic guitar amps, this seemed to work quite well, and even some relatively inexpensive ones sounded pretty good. In these applications a separate power amp was generally employed, note that power handling might be a concern more so if running these passively crossed; there is some risk at high spls of tweeter damage if the power amplifier is driven frequently or continuously into clipping.
It's a mistake IMO, and yes I have tried it. With mag pickups, you only want response up to maybe 7-8kHz max. Adding a tweeter will just add a bunch of hiss, noise and buzz. You are best off swapping the main driver for a semi full range unit like beta12LTA etc.
A mag pickup is always going to sound electric no matter what.
A mag pickup is always going to sound electric no matter what.
Yeah... I know I'm fighting physics here. I used the mag pickup because it helped me get pretty impressive mid-lows, with only rudimentary eq. But now here I am re-complicating the EQ again adding a boost for the highs. But I was hoping a tweeter would at least take the existing highs and at least offer a wider horizontal desperation. But then I'm back to the expensive tweeter issue.
Hi,
There is simply not enough information here to intelligently help.
An acoustic with a mag pickup is always going to sound pretty naff.
Which is why they are not common, and a budget add-on at best.
rgds, sreten.
There is simply not enough information here to intelligently help.
An acoustic with a mag pickup is always going to sound pretty naff.
Which is why they are not common, and a budget add-on at best.
rgds, sreten.
Sreten's right but...ehy! . The installation of the pick-up might be the cause
as the wood to where the PU is fixed has different velocity of sound propagation coefficient etc. and the PU has difficulty to pick the strings ( the thinner ones) which are rather far, and the wood superimposes its motion ( and stop) to the PU shell.
as the wood to where the PU is fixed has different velocity of sound propagation coefficient etc. and the PU has difficulty to pick the strings ( the thinner ones) which are rather far, and the wood superimposes its motion ( and stop) to the PU shell.
For a simple thing to try, a small piezo horn tweeter can be about $10. These can get shrill, but put it in series with a resistor of about 100ohms or maybe more, and it will calm it down. With that, you can wire it across your normal speaker with negligible change to amp load. The resistor is important. To further control it, increase the resistor or put another in parallel with the tweeter. The idea is to get it so you can hear it but its not too dominant.
I use a similar arrangement for playing acoustic through the guitar amp.
Another issue that affects your mag pickup is the capacitance of the guitar cable. There is more clear high treble to be had if you can build a very simple active buffer right into the guitar, or into the cable (involves mounting a jfet transistor into the jack plug)
An acoustic sim pedal can also help, or a processor with a suitable setting. Tbe Zoom G series have had a good acoustic sim for that last few versions.
I use a similar arrangement for playing acoustic through the guitar amp.
Another issue that affects your mag pickup is the capacitance of the guitar cable. There is more clear high treble to be had if you can build a very simple active buffer right into the guitar, or into the cable (involves mounting a jfet transistor into the jack plug)
An acoustic sim pedal can also help, or a processor with a suitable setting. Tbe Zoom G series have had a good acoustic sim for that last few versions.
Last edited:
As it turns out, the guitar does have a buffered output, which also offers more noise immunity. But its interesting you mention that Zoom pedal! I also have a Zoom G series pedal, and was pretty amazed the first time I tried that acoustic simulation. Even though i was playing with the neck pickup on a les Paul (with its characteristic mellow hum-buckers), its sounded like a new set of acoustic strings on a hollow body guitar. OK, not really as good, but a damn good simulation. I wonder how they do it and what circuits I could look up to try to do what its doing? Could it be its just a simple high end boost, or a parametric EQ optimized for 4Khz and up?
Always?
Personally I love the sound these guys get with an acoustic and a mag pic up.
https://www.youtube.com/watch?v=C3Iam7JELDM
https://www.youtube.com/watch?v=UsmxU8k0-HY
https://www.youtube.com/watch?v=BLF-f4kUtAw
Kinda goes with the genre.
You might try connecting the amp to a full range PA speaker or a cabinet from your stereo, just to hear what the amp and guitar pickup sound like full range. That will tell you how much of what you lack is speaker and how much is system. If the system doesn't deliver enough highs, a tweeter won't add any.
That's good advise! I've also now tried playing this acoustic through the Zoom G series acoustic simulator, as suggested by another poster, and I'm pretty impressed. As a DIY maker though, I'm not satisfied to just use this pedal now, i want to learn how it works and duplicate it. With that simulator connected, there are obviously more highs, and it shows through a good speaker. So I think the best approach will be hybrid... a tweeter, plus some electronic enhancement of the highs.
I've also been curious about acoustic sims. Here's a link to some schematics, based around the Boss pedal:
Wich Acoustic Simulator project?
It seems like it is indeed mainly just some carefully judged EQ, and in the case of the one linked above, quite a complex set up based around two quad opamps.
I'd think you could start exploring by recording the guitar (via buffer, which it has) into a pc and playing with EQ curves in Audacity or something similar. I also read that some of them add a bit of distortion to high frequencies to make more high harmonics.
But in a processor sim, there could be more happening. A bit of expansion and compression maybe? a touch of reverb/chorus?
The main thing that a real acoustic seems to have that no sim can fully capture is the percussive picking attack and miscellaneous string noises that add to its character
Wich Acoustic Simulator project?
It seems like it is indeed mainly just some carefully judged EQ, and in the case of the one linked above, quite a complex set up based around two quad opamps.
I'd think you could start exploring by recording the guitar (via buffer, which it has) into a pc and playing with EQ curves in Audacity or something similar. I also read that some of them add a bit of distortion to high frequencies to make more high harmonics.
But in a processor sim, there could be more happening. A bit of expansion and compression maybe? a touch of reverb/chorus?
The main thing that a real acoustic seems to have that no sim can fully capture is the percussive picking attack and miscellaneous string noises that add to its character
I certainly can see where the typical pizzo pickups used in most acoustics would enjoy significant output on a tweeter, and could even damage it without some limiting circuitry. But do you recall whether the tweeters did anything of value in the case of an an acoustic with a magnetic pickup? There is some high end there with a single coil, but it drops off quickly.
I know this is an old thread, but if you're still there I wonder if you have any thoughts on the best passive crossover frequency for that APEX JR. I tried using a 33 uF cap I happen to have a bunch of, which for an 8 ohm tweeter would be pretty low f, and sure enough it caused the whole system to have a bit of a hollow sound.
- Status
- Not open for further replies.