Hi,
I've just finished building my new desk, and have enough timber to make some nice matching desktop speakers.
I want them to be small, full range speakers, generally for watching movies, YouTube and some background music (I have headphones for serious music listening).
My main question is, can I power a set of 3"- 4" speakers from my headphone amp?
The amp in question is a Trilogy931, relevant specs :-
Input Impedance ≥50K Ohms
Gain (max) 18dB
Frequency response 20-20KHz +/- 0.5dB
Output impedance ≤ 10 Ohms
Output Power 800mW into 60 Ohms, 200mW into 300 Ohms
Distortion (THD) ≤ 0.05% 10mW into 300 Ohms
Signal to Noise Ratio ≥ 85dB A Weighted
After looking at other threads here, I've gravitated to either the Alpair 5.3, or the Fountek FR89EX
Would that amp power those ok?
Thanks,
Steve
I've just finished building my new desk, and have enough timber to make some nice matching desktop speakers.
I want them to be small, full range speakers, generally for watching movies, YouTube and some background music (I have headphones for serious music listening).
My main question is, can I power a set of 3"- 4" speakers from my headphone amp?
The amp in question is a Trilogy931, relevant specs :-
Input Impedance ≥50K Ohms
Gain (max) 18dB
Frequency response 20-20KHz +/- 0.5dB
Output impedance ≤ 10 Ohms
Output Power 800mW into 60 Ohms, 200mW into 300 Ohms
Distortion (THD) ≤ 0.05% 10mW into 300 Ohms
Signal to Noise Ratio ≥ 85dB A Weighted
After looking at other threads here, I've gravitated to either the Alpair 5.3, or the Fountek FR89EX
Would that amp power those ok?
Thanks,
Steve
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It rather depends on the output impedance.
You see, speakers are generally intended to be used with amplifiers with a near-zero output impedance. Even a couple of ohms between speaker & amp will change things quite dramatically. A 10ohm output impedance would be considered very high, and would therefore require a different design approach to the speakers.
Even then, the output levels are quite low. You might find that, while the headphone amp will certainly get the speakers to make some noise, it might be quite quiet.
I expect your headphone amp is protected against driving low impedances, but at the same time, why risk it? Small class D amps are cheap, and can even run on 5V USB power.
Chris
You see, speakers are generally intended to be used with amplifiers with a near-zero output impedance. Even a couple of ohms between speaker & amp will change things quite dramatically. A 10ohm output impedance would be considered very high, and would therefore require a different design approach to the speakers.
Even then, the output levels are quite low. You might find that, while the headphone amp will certainly get the speakers to make some noise, it might be quite quiet.
I expect your headphone amp is protected against driving low impedances, but at the same time, why risk it? Small class D amps are cheap, and can even run on 5V USB power.
Chris
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Sure, no problem.
FWIW, if you're running sound out of a PC, then you can use Equaliser APO to overcome some speaker deficiencies.
For instance, we typically want plenty of low-frequency extension, but don't want to use huge cabinets to get there. What I've done with my desktop speakers is to use sealed boxes, and then EQ the result (search Linkwitz Transform for lots of discussion in that direction). The result is flat-to-35Hz extension, which can't really be obtained any other way.
I use an old Akai amp (25w/ch) and a pair of Kef HTS3001SE with the bass ports blocked.
If I play some dubstep and turn it up, it's easy enough to give the drivers some pain. At sensible levels, though, I can enjoy the music without having to mess around with subwoofers.
Chris
FWIW, if you're running sound out of a PC, then you can use Equaliser APO to overcome some speaker deficiencies.
For instance, we typically want plenty of low-frequency extension, but don't want to use huge cabinets to get there. What I've done with my desktop speakers is to use sealed boxes, and then EQ the result (search Linkwitz Transform for lots of discussion in that direction). The result is flat-to-35Hz extension, which can't really be obtained any other way.
I use an old Akai amp (25w/ch) and a pair of Kef HTS3001SE with the bass ports blocked.
If I play some dubstep and turn it up, it's easy enough to give the drivers some pain. At sensible levels, though, I can enjoy the music without having to mess around with subwoofers.
Chris
Even a basic “Lunch Money” amp TDA7297 for $5 will give you vastly improved sound vs using an 800mW headphone amp to drive those speakers. This amp has a lot of bang for the buck if cost is what is preventing you. It’s Class AB quasi complementary output. Give is a good linear PSU and sound will be even better than 12v wall wart. You can still use the headphone amp as a preamp to drive the TDA7297.
What the heck? It's less than lunch!
What the heck? It's less than lunch!
For music I have PC out, into a Bifrost dac, through the Trilogy 931, then to a set of Focal Elears or Sennheiser 800s's. I live in a small flat, so 'phones are really the only sensible option.
Having said that, I've wanted to build a proper set of nice desktop speakers for years, and every so often I find myself here, determined to get them done, then I get bogged down in port sizes, cabinet volumes, crossovers, resistances, graphs ............. and I drift off somewhere else
This time, as I said previously, I've just made a nice desk from some skip timber I found, and having a bit left over I'd really like to finally get them done.
I'd never considered full range speakers, but after seeing some of the threads here, and how highly regarded the Fountek and Alpair are, they seem ideal - more building and less calculating !
Having said that, I've wanted to build a proper set of nice desktop speakers for years, and every so often I find myself here, determined to get them done, then I get bogged down in port sizes, cabinet volumes, crossovers, resistances, graphs ............. and I drift off somewhere else
This time, as I said previously, I've just made a nice desk from some skip timber I found, and having a bit left over I'd really like to finally get them done.
I'd never considered full range speakers, but after seeing some of the threads here, and how highly regarded the Fountek and Alpair are, they seem ideal - more building and less calculating !
Attachments
It's not the cost that holds me back, it's my complete and total lack of electrical knowledge
My day job revolves around CAD/CNC, and carpentry is my weekend pass-time. Closest I come to electrics is plug wiring
+1
The sound from this little wonder amp still amazes me. While I have a Class A amp for other duties, I use this TDA7297 on a daily basis driving Tannoy monitors. I have also played around with TPA3116 amp boards, but nothing beats the best bang for your buck TDA7297. I bought mine as a kit for $2 and only upgraded the input and output caps.
That's only the chip. We're talking about a complete board like this:
TDA7297 Version B Amplifier Board DC 12V 2x15W Digital Audio Dual Channel Module 15W +15W Grade 2.0 Finished|Replacement Parts & Accessories| - AliExpress
You still have to build it into a box with connectors and get a power supply.
Sorry, this thread is really about desktop speakers. I would suggest these:
XKi - X's ab initio Karlson 6th Order Bandpass
Not sure why xrk971 did not recommend his own design. But he uses it in the kitchen while cooking I guess.
TDA7297 Version B Amplifier Board DC 12V 2x15W Digital Audio Dual Channel Module 15W +15W Grade 2.0 Finished|Replacement Parts & Accessories| - AliExpress
You still have to build it into a box with connectors and get a power supply.
Sorry, this thread is really about desktop speakers. I would suggest these:
XKi - X's ab initio Karlson 6th Order Bandpass
Not sure why xrk971 did not recommend his own design. But he uses it in the kitchen while cooking I guess.
Cheers Jeff.
It started off as some old science desk legs and runners I found in a skip, and a very old piece of desktop.
Came out nice in the end
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Thank you Twocents
Those speakers are much larger than I had in mind - ideally I'd like them only about 4 1/2" wide, 12"-15" high, depth isn't really an issue.
The 0.40x mini Karlsonator might be more along the size you seek.
Mini Karlsonator (0.53X) with Dual TC9FD's
Boxed TPA3116 amp with Bluetooth is quite a deal lately.
US $12.08 30％ Off | 50W*2 Bluetooth 5.0 TPA3116D2 HiFi Power Amplifier Finished Board In Case Home Audio TPA3116 Amp With Treble Bass I4-005-6
50W*2 Bluetooth 5.0 TPA3116D2 HiFi Power Amplifier Finished Board In Case Home Audio TPA3116 Amp With Treble Bass I4 005 6|Amplifier| - AliExpress
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You should be able to find some inexpensive "25-volt distributed line matching transformer" - many places have them, they're used for distributed ceiling speakers and the like. They have taps so each speaker can be adjusted for level independently. Here's an example:
Bogen Communications, Inc. - T72510 - Transformer, Speaker Matching 8-ohm Speakers 3" W x 1-1/2" H x 1-1/2" D 10-watt - Allied Electronics & Automation
Set for 10W at 25v, it will turn an 8-ohm speaker into a 62.5-ohm load, which will extract 0.8 watts from your headphone amp - should be plenty for your application.
Bogen Communications, Inc. - T72510 - Transformer, Speaker Matching 8-ohm Speakers 3" W x 1-1/2" H x 1-1/2" D 10-watt - Allied Electronics & Automation
Set for 10W at 25v, it will turn an 8-ohm speaker into a 62.5-ohm load, which will extract 0.8 watts from your headphone amp - should be plenty for your application.
Thanks Paul - that looks brilliant, but I've ordered a couple of those little amps suggested by XRK.
I have a specific design/look I want for the speakers - I think I'll put one of those amps into one of the enclosures and, as suggested, use my can amp as a pre-amp.
Next decision is to choose between either the Alpair 5.3, or the Fountek FR89EX
I have a specific design/look I want for the speakers - I think I'll put one of those amps into one of the enclosures and, as suggested, use my can amp as a pre-amp.
Next decision is to choose between either the Alpair 5.3, or the Fountek FR89EX
I really like the look of the gold Alpair's, and I've just seen the Alpair 7ms
Are there any reasons I shouldn't use this for the speakers I have planned?
Thanks
Are there any reasons I shouldn't use this for the speakers I have planned?
Thanks
It'll be fine for what you have in mind. A 3" cone is a little on the small side for serious LF extension (even at desktop levels), but 50Hz-ish would be attainable.
That's assuming, of course, that you go for sealed + EQ.
Conventional ported boxes would be larger, but also much more efficient.
Chris
That's assuming, of course, that you go for sealed + EQ.
Conventional ported boxes would be larger, but also much more efficient.
Chris
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