I just finished a 3-way semi-active build based on the DSP, TPA3251 and TPA3255 boards from 3e Audio. I thought the build could be of some interest for other members sitting on the same or similar components.
I have documented the whole build on my build-blog: The 3-Way Retro
I have documented the whole build on my build-blog: The 3-Way Retro
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Very interesting!
Have you tried 3:rd order acoustic filtering between woofer and midbass ?
My experience with my active 3-way dsp loudspeaker has shown good results with such crossovers at that frequency region. I use 24 dB linkwitz Riley acoustical slopes between tweeter and midrange.
Have you tried 3:rd order acoustic filtering between woofer and midbass ?
My experience with my active 3-way dsp loudspeaker has shown good results with such crossovers at that frequency region. I use 24 dB linkwitz Riley acoustical slopes between tweeter and midrange.
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Thanks Audientid14, I will try it out as soon as I get the time to do a new set of in room measurements. I have been quite busy just playing around with the DSP. I think it is great for straight forward things like a crossover or a Linkwitz transform. It is tempting to add some of the ADI Algorithms or dynamic processor stuff. It is fun but feels a bit convoluted after a while. I ma learning as I go and I have already made some changes. I will make an updated blog post as soon as things settle. But I have to say that I am starting to get really pleased with this set of speakers. I guess some of it has to be attributed to the DSP...
Hi EmuMannan, thanks for a great blog series! I have been thinking about using this DSP chip and it was good to read your experiences
One thing I am still trying to figure out is where I want gain. I kind of assumed unity gain trough the DSP (as long as you don't program it to apply gain). I am used to a preamp (including RIAA stage) and a power amp. But I noted the audio specification for the EDSP-1701-24-A stated a typical voltage gain (Av in the specification) of 10 dB @ 1 kHz. I still don't know if this is balanced or unbalanced (I have sent 3e Audio a question about it). I use balanced connections to my EAUMT-0140-2-A and EAUMT-0260-2-B boards. If the DSP is adding 10 or even 16 dB to whatever I already programmed it to have (e.g. a Linkwitz transform, room EQ etc.) then that's a lot. Especially if you also add gain from your preamp. I guess 3e Audio intended the DSP to be used as a premap. But the extra gain is worth taking into account if you plan to use the DSP as an active filter and already got a preamp.
In general or what I did? I got gain all over the place. A RIAA stage of 40 dB. A preamp with configurable gain currently set at 7 dB. Two power amps with a set gain of 20 and 21.5 dB. The DSP goes in between the preamp and the power amps and it seems to have at least 10 dB. That is a lot if you consider a TT cartridge of 5 mV + 40 dB -> 0.5 V + 7 dB -> 1.1 V + 10 dB -> 3.5 V + 20 dB -> 35 V (into 4 ohms speakers -> 306 W and 8.75 A). And 3.5 V into the power amp might be more than its input sensitivity. And this is without any gain programmed into the DSP. So where do you place it? I added a compressor to act as a limiter to prevent the DSP to feed the power amps more than their input sensitivity. And I include an attenuator as part of the DSP program in order to set normal listening level equal to 12 a-clock on my preamps volume knob. It is not perfect but it works...
Ps. My DAC is as hot as many CD-players outputting 2.128 Vrms at 0 dB attenuation: 2.1 V + 7 dB -> 4.7 V + 10 dB -> 14.9 V + 20 dB -> 149 V (into 4 ohms speakers -> 5550 W and 37.25 A). I guess you get the idea...
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Interesting, I've got the same amplifiers waiting at the customs, so this might give me some much valued help.
The amplifier boards are great. Really nice build quality and sound. My muting circuit works perfectly (by grounding the RESET pin). I got no pops or noise on power on or off. Note the input sensitivity with a voltage gain of around 20 dB (x10). The boards got balanced input and I guess you loose 6 dB if you feed them unbalanced. So balanced x10 and unbalanced x5 voltage gain. If you got the TPA3255 board and feed it 48 V then you get 4.8 V vs 9.6 V input sensitivity (as a rough estimate).
I will se how I solve the details later, but I will use the 3e DSP as preamp so I'm guessing level adjustment will be relatively easy to do.
PSU is not decided yet, but I have looked at Meanwell.
I will take some time later and go through your page.
PSU is not decided yet, but I have looked at Meanwell.
I will take some time later and go through your page.
Yes and you can run balanced between the DSP and the power amps.
I can recommend the ones from Connex Electronic if you want to go switch mode. SMPS600RS for example is powerful yet compact.
The idea (at least) is to have DSP and amp in the same chassi. But I'll cross that bridge when I know I can make it work the way I want it to.
I have read mixed reviews about Connex, so I'm looking at other options right now, at least.
I have read mixed reviews about Connex, so I'm looking at other options right now, at least.
I finally got an answer from 3e Audio about the DSP Av gain (stated as 10 dB in the audio specification). It is for balanced output according to 3e Audio. The example I was given was an input of 0.9 Vrms and an output of 3.3 Vrms. It was stated as "around 10 dB" but it actually equals 11.3 dB (x3.7). I guess it would equal a voltage gain of 5.3 dB (x1.8) for unbalanced output. Good to know if you run into a headroom problem at the receiving gear...
Hi @EmuMannen !
So fantastic to have found your topic / build - It's exactly what I am working on right now!
I've ordered from 3E the 1x480W TPA3255, the 2x260W TPA3255, and the DSP board.
These will go into an amplifier case, and will power a single 3 way speaker.
Crossover to be done by the DSP in the amplifier - the amp unit will have 3 pairs of Speakon connectors going to the speaker which will have 3 Speakon connectors going straight to the drivers.
Ofcourse, this one amplifier-and-speaker is my test-bed - once I get it the way I like it I'll make a matching pair ;-)
So fantastic to have found your topic / build - It's exactly what I am working on right now!
I've ordered from 3E the 1x480W TPA3255, the 2x260W TPA3255, and the DSP board.
These will go into an amplifier case, and will power a single 3 way speaker.
Crossover to be done by the DSP in the amplifier - the amp unit will have 3 pairs of Speakon connectors going to the speaker which will have 3 Speakon connectors going straight to the drivers.
Ofcourse, this one amplifier-and-speaker is my test-bed - once I get it the way I like it I'll make a matching pair ;-)
It is still available but under another label (3WR): https://emumannen.blogspot.com/search/label/3WR
It is some eleven posts in total... Starting with this one: https://emumannen.blogspot.com/2020/09/the-3-way-neo-part-1.html
Summery is this post: https://emumannen.blogspot.com/2021/03/the-3-way-retro-revisit-1.html
And a fully passive version in this post: https://emumannen.blogspot.com/2021/07/the-3-way-retro-update-2.html
(Sorry about that old link not being updated but the label changed when I changed the name of the speaker)
It is some eleven posts in total... Starting with this one: https://emumannen.blogspot.com/2020/09/the-3-way-neo-part-1.html
Summery is this post: https://emumannen.blogspot.com/2021/03/the-3-way-retro-revisit-1.html
And a fully passive version in this post: https://emumannen.blogspot.com/2021/07/the-3-way-retro-update-2.html
(Sorry about that old link not being updated but the label changed when I changed the name of the speaker)
Hello Emumannen and happy new year.
I have read some of your project and find it very interesting. I have a Texas Instrument TPA3255, and a SMPS 48V that I have had some plans to build a 3 way out of. My plan is also to add a sub. The drivers you have chosen also seem well thought out. The DSP was new to me, with a semi version, but this also seems interesting.
I would consider using my current TI amp on mid and high and then getting an additional TPA3255 for the woofer. How satisfied are you with your version of the TPA3255? Does this have any kind of noise? I guess this depends on the quality of the power supply.
I have read some of your project and find it very interesting. I have a Texas Instrument TPA3255, and a SMPS 48V that I have had some plans to build a 3 way out of. My plan is also to add a sub. The drivers you have chosen also seem well thought out. The DSP was new to me, with a semi version, but this also seems interesting.
I would consider using my current TI amp on mid and high and then getting an additional TPA3255 for the woofer. How satisfied are you with your version of the TPA3255? Does this have any kind of noise? I guess this depends on the quality of the power supply.