Amplifier recommendation for DIY speaker build please.

[CPTX]

I am combining two 8 ohm full range drivers of similar frequency response, but slightly different RMS ratings in parallel. They will be together in a shared 1 cubic foot enclosure (I can seal them off from each other if that’s strongly recommended…but I basically added their recommended individual sealed sizes)

I am prioritizing simplicity and low cost over decibels; but don’t want to hear struggling.

These are the two speakers.

 

[CPTX]

My first thought is the $70 Aiyima A07max with the 48 volt ten amp power supply.

I see Erin’s Audio corner documented these numbers in mono/PBTL mode (with the 48V 10amp power supply)

 

[CPTX]

If there are other amplifier options I should consider, or any other suggestions, please let me know.

….this is primarily for low cost fun with the speaker and amplifier being used outside and/or in the garage.

Thank you.

 

[Zek]

I am combining two 8 ohm full range drivers of similar frequency response, but slightly different RMS ratings in parallel.

In the combination of those two speakers, the problem is not the different RMS powers, but the problem is that there is a big difference in sensitivity, so the second speaker will be louder than the first.
In addition, in a parallel connection, the total impedance will be around 4 ohms (in some cases even less), which is not desirable for an amplifier, so you have to find an amplifier that is stable on a 4 ohm load.

 

[CPTX]

Ahhh, thank you…I won’t mind the second driver being louder as it has a wider frequency response.

The Aiyima A07max appears to be stable under 4 ohm loads.

Will AIYIMA A07 work with 4ohm//2.2uF load? - Test and measurements

Will AIYIMA A07 work with 4ohm//2.2uF load? - Test and measurements You might get surprised :) (or maybe not, those who are knowledgeable). In my latest test thread, I have shown how the Hypex NC252MP failed to drive 4ohm in parallel with 2.2uF load, the load simulating some of the...

www.audiosciencereview.com

 

[Zek]

The basic question is what you want to achieve with this choice of drivers.
The first driver will not be heard at all in such a setting.
Maybe it's better if it's just the second driver in the box.

 

[Hear Here]

I am combining two 8 ohm full range drivers of similar frequency response, but slightly different RMS ratings in parallel. They will be together in a shared 1 cubic foot enclosure (I can seal them off from each other if that’s strongly recommended…but I basically added their recommended individual sealed sizes)

Are you planning to use an 8" and a 4" driver in parallel? Surely not? Assuming your 2 bass drivers are similar and housed in such a small enclosure, have you considered an isobaric design? This design will kid the front speaker (the one you can see) into thinking it's in a much larger enclosure and it will deliver far better and deeper bass, if well implemented.

Or have I misread and you intend to use these 2 drivers as full-range devices with no crossover? This would be most unconventional and your treble would be poor as you have no tweeter as such. Also the small speaker would no be protected from the bass frequencies.

Regarding an amplifier, I'd suggest one that includes a "room correction DSP" feature as this processor has no idea of where the peaks and troughs are generated. It merely measures what the microphone picks up at the listening position and does its best to adjust the frequency response to compensate for these peaks and troughs, whether caused by the room or the speakers. In the case of a DIY speaker, where you are not building dozens of prototypes to judge and compare (as brands do), DSP should do good.

I think we need to know more about your ideas regarding crossovers, cabinet design, etc.

PS - Although very old and out of print, there are 3 great books written by G A Briggs, the founder of Wharfedale, that go into DIY speaker theory and practice in a very understandable way. Accepting their age, you may find useful information there. His books are Loudspeakers, More About Loudspeakers and Cabinet Handbook. I found the last one the most helpful when I was building my own speakers in my mis-spent youth! Copies likely available from Amazon, Abe Books and other used book sites. Good luck.

 

[CPTX]

The basic question is what you want to achieve with this choice of drivers.
The first driver will not be heard at all in such a setting.
Maybe it's better if it's just the second driver in the box.

Thank you all for the feedback….much appreciated.

The recommended sealed enclosure size on parts express for the 8 inch driver is listed at 0.75 cubic feet.

The recommended sealed enclosure size for the 4 inch driver is 0.15 feet.

Thus, my instinct was a one cubic foot enclosure.

Hearing that this will be too small is good news, as the enclosure I’ve made is 2.1 cubic feet…..I was going to shave it down to 1 cubic feet; but I’d actually rather not.

 

[CPTX]

The 8 inch and 4 inch full range driver recommended sealed enclosure information below.

 

[CPTX]

The front panel of the cabinet is 16 inches by 16 inches. I chose full range drivers to keep things simple (no crossover absolutely needed…..and with my high frequency hearing loss…..I won’t miss anything higher than 16k)

Thus, I chose an 8 inch 8 ohm driver and a 4 inch 8 ohm driver to fit on the front of the cabinet.

 

[Zek]

I chose an 8 inch 8 ohm driver and a 4 inch 8 ohm driver to fit on the front of the cabinet.

Why did you choose two completely different drivers in terms of characteristics when you don't want to install a crossover?

 

[CPTX]

Thanks again for your help here as I’ve clearly goofed on keeping it simple.

The front panel of the cabinet is 16 inches square.
8+4 fits easily with wiggle room.

Other than six passive subwoofers, I haven’t built a speaker before, and innocently thought if I purchased two full range drivers with the same impedance, very similar frequency responses, and somewhat similar sensitivities; I would be keeping things relatively simple.

My first mistake was painting myself into a corner by making the cabinet first.

If I had made it say….20”x 20”x20”…I would have just purchased two identical eight inch full range drivers.

Currently thinking of some work arounds and plan Bs with the priorities of keeping things simple and low cost.

I will have no problems making another cabinet…then possibly joining them together… and it wouldn’t break my heart to purchase another amp.

 

[Zek]

Making sound boxes requires a little research into the relevant literature.
You can't just order a box and push a driver into it without calculating the shape and volume of the box according to the electrical parameters of the selected driver.
An even worse decision is to pick two random drivers and try to put them in one box without any crossover.
It doesn't work like that...

 

[Hear Here]

Don't be deceived by the description "full range driver". None are true full range, as it requires a very different driver to deliver good bass compared with one that's expected to deliver delicate tingle-factor top end.

A cubic enclosure is unlikely to give good sound for the same reason that cubic rooms are generally avoided. Cube OK for subs but not full-range main speakers. XOs needn't be complex and they really are necessary to separate the frequency range that suits the frequencies favoured by 2 or 3 drivers. Good luck anyway

 

[CPTX]

Thank you; Yes, I certainly see the benefits of a more vertical shape and the almost inevitability of a crossover here.

 

[hex168]

Tell us more about what you are trying to do and we can help more. Did you build two cabinets? If not, what are you trying to achieve with one speaker? If you have not bought the drivers yet, once you tell us your goals and budget perhaps we can recommend something that will use the cabinets you already built. Speaker design is a complicated engineering discipline; often the best place to start is with an existing kit design.

Not a bad idea to read a book or two first.
The best one, expensive, is the Loudspeaker Design Cookbook by Vance Dickinson. Older editions should be available used, cheaper. Or, start by reading this thread, with lots of useful links:

So you want to design your own speaker from scratch!

You have been doing this DIY speaker thing for a while, probably built a couple of proven designs from people like Zaph , Troels Gravesen, Paul Carmody or any number of other successful designers. Perhaps you started out like me, cobbling together random drivers with off the shelf or...

www.diyaudio.com

If you want easy, put one of these in a box. Recommended box sizes and port sizes are listed:

SB Acoustics SB20FRPC30-8 8" Paper Full Range

SB Acoustics SB20FRPC30-8 8" Paper Full Range

www.madisoundspeakerstore.com

Once you build that, you can start on learning measurement and EQ.

 

[CPTX]

I have one cabinet, one Aiyima A07max, and the two speakers above.

Yes, I now realize that with my naïveté and speaker choices, that I have jumped into the deep end without adequate preparation.

This is primarily for fun as I enjoy the process of making things. Creating a speaker that sounds great is not the goal.

I have a work around with my current skill level as I do have experience making DML/XPS exciter speaker panels. They are “full range” above 200Hz and have a nice, pleasing top end…very easy to make.

Plan B using a preamp I already have and an RCA distribution box to three small amplifiers to each component of the speaker.
1. 16x16x16” cabinet for the “full range” 8 inch driver in the cube cabinet driven by the Aiyima A07max
2. 14”high x 8”wide x 6” deep cabinet section for the “full range” 4 inch driver likely powered by another AO7 max
3. Then on top the exciter speaker powered by a low cost $50 mono amp in PBTL mode.

Then I’ll buy some books on speaker design and start reading.

 

[Zek]

1. 16x16x16” cabinet for the “full range” 8 inch driver in the cube cabinet driven by the Aiyima A07max
2. 14”high x 8”wide x 6” deep cabinet section for the “full range” 4 inch driver likely powered by another AO7 max

I guess you will use A07Max in mono mode for each of these speakers.
Do you think you make two speakers with 8 "driver and two speakers with 4" driver, or just one box from each?
How do you think you have a stereo effect when you only have two different speakers?
How do you think you connect everything and what will be a sound source?
In my opinion, it is a pity to use two A07Max on such a project ...

 

[CPTX]

Agree; plan B was brainstorming.
^^^scratch my Plan B above and reading books on speaker construction.

Plan C
Hold onto the 4 inch PC105-8 “full range” driver for a future project.

Get this 4 inch “full range” instead (same company, same sensitivity) and go back to plan A with one Aiyima A07max + hybrid of using the exciter speaker for the top end off the preamp I already have….already have a couple of exciter speakers I can use from a previous project also.

 

[CPTX]

Yes, this will be a speaker in mono.
It’s my first multi driver full range speaker (not counting previous projects with passive subs + DML XPS exciter panel speakers).

I’ll tackle left and right channel speakers using the 4” “full range” speaker I’ll be saving from this project.