Longtime builder, but old-school 2 way all my life. I started building speakers in 1969, long before all the science of today but they sounded mighty fine to me.
I'm now retired, so I thought I'd try a 3 way sealed design. I'm limited in fabrication tools, but I think you'll see my compromise in this parts list:
Volumes will be 3.7cu ft for the low, 0.7cu ft for the mid. I'll add some bracing, but these cabinets are 3/4" thickness and very well made. My driver choices were done the same as always (seat of the pants judgement), but I also modeled in WinISD and things look good to me.
A major goal is high efficiency, amp will be EL34 2x7w.
All comments are welcome!
Links to components in Post #6
(edited 11-5-2024 to reflect change in 15" and horns)
I'm now retired, so I thought I'd try a 3 way sealed design. I'm limited in fabrication tools, but I think you'll see my compromise in this parts list:
| PRV Audio 10MB800FT 10" Professional Midbass Driver 8 Ohm | 294-2988 |
| PRV Audio 15SW2000 15" Pro Audio Subwoofer 8 Ohm | 294-3007 |
| PRV Audio D290Py-B 1" Polyimide Horn Compression Driver 8 Ohm | 294-2833 |
| PRV Audio 3DF400/1800 Three-Way Crossover Board 400/1,800 Hz | 294-2869 |
| B&C ME45 1" Exponential Horn 90x40 2-Bolt | 294-622 |
| Parts Express Gold Recessed Binding Post Banana Jack 5-Way Speaker Terminal | 260-309 |
| KLËARVŪE Cabinetry® 18"W x 14"D x 40"H Wall Cabinet - Box Only | 4780022 |
| KLËARVŪE Cabinetry® 18"W x 14"D Shelves - 2 pk | 4783504 |
| 3/4 x 2 x 4 Oak Plywood Handi-Panel | 1254541 |
| Thermafiber Ultrabatt R13 Mineral Wool Insulation 3.5" x 15" x 47" 39 sq ft | 1200064 |
Volumes will be 3.7cu ft for the low, 0.7cu ft for the mid. I'll add some bracing, but these cabinets are 3/4" thickness and very well made. My driver choices were done the same as always (seat of the pants judgement), but I also modeled in WinISD and things look good to me.
A major goal is high efficiency, amp will be EL34 2x7w.
All comments are welcome!
Links to components in Post #6
(edited 11-5-2024 to reflect change in 15" and horns)
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I'll wade in, but there are many here far more qualified than I to comment.
I wasn't familiar with your cabinet choice so did a quick Google search, but couldn't find your exact cabinet. Interesting concept, but from what I could see, the cabinets have a 1/2" thick wall. If they're like Ikea, they're assembled with dowels? What's the cabinet back: 1/4"? My first thought is that type of cabinet is just not substantial enough for pro drivers, perhaps for any drivers, and is going to buzz and rattle.
Which leads me to my next point: you mentioned a sealed cabinet. I don't have the app on this computer to do a quick check, but is that woofer better suited to a vented cabinet? Have you run any projections as to what the Fb and F3 will be with that woofer, sealed or vented in a cabinet of that size?
Your choice of a 10" mid crossing at 400 makes sense, but given that's a 'canned' crossover, will it provide for the different sensitivities of the drivers?
I don't have any knowledge of the B&C horn in combo with that PRV driver, so may be good, may not. Others may be in a better position to comment.
To summarize, my concerns would be: the cabinet choice; the cabinet size re that woofer; whether that woofer is suited for sealed; whether that crossover will allow for the various sensitivity levels of those drivers.
I wasn't familiar with your cabinet choice so did a quick Google search, but couldn't find your exact cabinet. Interesting concept, but from what I could see, the cabinets have a 1/2" thick wall. If they're like Ikea, they're assembled with dowels? What's the cabinet back: 1/4"? My first thought is that type of cabinet is just not substantial enough for pro drivers, perhaps for any drivers, and is going to buzz and rattle.
Which leads me to my next point: you mentioned a sealed cabinet. I don't have the app on this computer to do a quick check, but is that woofer better suited to a vented cabinet? Have you run any projections as to what the Fb and F3 will be with that woofer, sealed or vented in a cabinet of that size?
Your choice of a 10" mid crossing at 400 makes sense, but given that's a 'canned' crossover, will it provide for the different sensitivities of the drivers?
I don't have any knowledge of the B&C horn in combo with that PRV driver, so may be good, may not. Others may be in a better position to comment.
To summarize, my concerns would be: the cabinet choice; the cabinet size re that woofer; whether that woofer is suited for sealed; whether that crossover will allow for the various sensitivity levels of those drivers.
Without links to the products you list and without data all people can offer is a WAG
But from my POV a 10" midbass needs at least two 12" woofers for SPLs to match up. 15" should work also Pro drivers [ which I guess these are] are much better suited to electronic crossovers and Bi or Tri amping to avoid the large losses in the small gauge wire that is usually used in off the shelf crossovers at low frequencies.
Secondly if the cabinets are the usual chipboard and melamine held together with dowels that will be too weak and not even close to airtight without the use of lots of epoxy glue.
Thirdly 7 watts may not be enough to drive any of those let alone all 3 combined
But from my POV a 10" midbass needs at least two 12" woofers for SPLs to match up. 15" should work also Pro drivers [ which I guess these are] are much better suited to electronic crossovers and Bi or Tri amping to avoid the large losses in the small gauge wire that is usually used in off the shelf crossovers at low frequencies.
Secondly if the cabinets are the usual chipboard and melamine held together with dowels that will be too weak and not even close to airtight without the use of lots of epoxy glue.
Thirdly 7 watts may not be enough to drive any of those let alone all 3 combined
Links:
PRV Audio 15W1000v2 15"
PRV Audio 10MB800FT 10"
PRV Audio D230Ti-B 1"
B&C ME45 1" Exponential Horn
PRV Audio 3DF400/1800 Three-Way Crossover
18"W x 14"D x 40"H Wall Cabinet
The cabinet sides are 3/4" thick particle board, rear is half 1/2" and half 1", it will be filled to 1" thick overall. They will be caulked at all edges and reinforced internally with L brackets and additional bracing. The baffle will be 3/4" plywood.
I've considered venting, but the volume is a shade low.
I see no issues with power unless someone knows something I don't understand...? All drivers are quite high efficiency.
PRV Audio 15W1000v2 15"
PRV Audio 10MB800FT 10"
PRV Audio D230Ti-B 1"
B&C ME45 1" Exponential Horn
PRV Audio 3DF400/1800 Three-Way Crossover
18"W x 14"D x 40"H Wall Cabinet
The cabinet sides are 3/4" thick particle board, rear is half 1/2" and half 1", it will be filled to 1" thick overall. They will be caulked at all edges and reinforced internally with L brackets and additional bracing. The baffle will be 3/4" plywood.
I've considered venting, but the volume is a shade low.
I see no issues with power unless someone knows something I don't understand...? All drivers are quite high efficiency.
Specs for the amp:
- Rectifier tube: 5U4G
- Preamp tubes: 6H8C ×2
- Power tubes: EL34B × 2
- Rated output power: 10W*2(ultra-linear connection)
- Frequency response : 20Hz - 25KHz
- Power consumption: 105W
- Output transformer: Japan Z11 0.35mm(22x45/50)
- THD : 1% (1kHz)
- Input Sensitivity : 500mV - 2000mV
- Input impedance : 100KΩ
- Output Impedance : 4Ω / 8Ω
- SNR : 88dB
Considering "Qtc", I honestly have no idea what that is. I'll try to educate myself and get back to you.
I am concerned about the LF response, and would like to see it lower. Again, this is the reason for the post, to get input from those with more knowledge.
"This driver will deliver a powerful midbass punch with smooth response through the vocal range making it great for high-power two or three-way systems".
That is the blurb for the 10"
Hi power in this instance is measured in kilowatts
But go for it and learn something in the process I guess
That is the blurb for the 10"
Hi power in this instance is measured in kilowatts
But go for it and learn something in the process I guess
Don't see where you said 'bought', just a list and by 'pursue', meant such a too small cab for typical HIFI/HT apps. Also, it's been so many decades since I calculated a tube amp's output impedance (AKA damping factor) that I'm not even sure you listed enough specs 🙁.
Anyway, typically when asked for it, folks list the tap ratings (your 4/8 ohms), which implies a matching impedance amp (DF = 1), so is it or is there a DF rating not listed?
Note that if we assume a DF = 1, then Qts zooms to 1.59 min (Rs = 8) at which point it ideally needs to be XO'd at the driver's upper mass corner = 2*(Fs)/Qts = < ~50 Hz to keep its excessive 'ringing' from ruining the speaker's overall performance; obviously not a good plan except loading it with a small open baffle to allow the effective Qt to go down enough to increase its upper mass corner to allow a much higher XO point with the trade off that there will be less bass output since we're always trading efficiency for bandwidth (BW).
That's a traditional acoustic solution, so of course there's passive electrical filters, electronic solutions with DSP being the most popular nowadays since the prices have dropped so much in recent years.
Qtc and the math I used, so you can 'do the math' to see how big a cab you ideally need to go low at different Qtc values.
Anyway, typically when asked for it, folks list the tap ratings (your 4/8 ohms), which implies a matching impedance amp (DF = 1), so is it or is there a DF rating not listed?
Note that if we assume a DF = 1, then Qts zooms to 1.59 min (Rs = 8) at which point it ideally needs to be XO'd at the driver's upper mass corner = 2*(Fs)/Qts = < ~50 Hz to keep its excessive 'ringing' from ruining the speaker's overall performance; obviously not a good plan except loading it with a small open baffle to allow the effective Qt to go down enough to increase its upper mass corner to allow a much higher XO point with the trade off that there will be less bass output since we're always trading efficiency for bandwidth (BW).
That's a traditional acoustic solution, so of course there's passive electrical filters, electronic solutions with DSP being the most popular nowadays since the prices have dropped so much in recent years.
Qtc and the math I used, so you can 'do the math' to see how big a cab you ideally need to go low at different Qtc values.
I was under the impression that sensitivity is irrespective of power handling capability, and this is why it is stated as 2.83V/1m for all drivers.
This driver is rated 99dB. To compare, I swapped one with a Visaton W250S in my current main set. Though this box is totally unsuited for the PRV (2.5cu ft vented), that side was markedly louder. I could measure the dB, but you get the idea.
I maintain that sensitivity has nothing to do with power handling; the higher handling number merely represents a higher upper limit in dB using more power. Are you disagreeing based on the PRV's description?
As I understand it, you're saying that a tube amp requires a completely different speaker design than a solid state amp. This has never been my experience.
If folks typically respond with the "tap" ratings when you ask for output impedance as I did, I think you may be asking the wrong question.
In any event, and as I explained in my opening post, I'm "old-school". If that also means "ignorant", I'll accept that title too. The use of WinISD is new to me, though quite understandable. Your foray into advanced math, though impressive, is way above me.
Have you thought about power dissipation in that commercial XO?
I was actually thinking that you would lose several watts in resistance and heat in that XO
But also big drivers need a bit more power to get them moving
I was actually thinking that you would lose several watts in resistance and heat in that XO
But also big drivers need a bit more power to get them moving
No, I had not considered the crossover taking power, this seems reasonable!
Concerning sensitivity, I always thought the actual tests were done at 1w, or 2.83v nowadays. Is this true, or is this a calculated value based on tests at much higher powers?
If it is calculated from higher than 2.83v input, we need a new sensitivity parameter or formula that incorporates power handling!
Digging deeper into potential power dissipation in the crossover, I find that the low and mid have no appreciable resistance. They are merely lowpass/bandpass (unless the mid attenuation feature is used).
The HF also has attenuation that will likely be used, I'm using L-pads on my current setup with no power problems so this should not be an issue.
The HF also has attenuation that will likely be used, I'm using L-pads on my current setup with no power problems so this should not be an issue.
I use a similar 10" mid in one of my party boxes, although not able to handle as much power; while sensitive enough at 89dB it needs at least 10 watts to get to a listening volume Bi-Amped but needs much more power to handle short transient peaks in orchestral music.
You may need more power than you think to power a 3-Way
You may need more power than you think to power a 3-Way
Those are copper wire coils and will have appreciable resistance.
All you can do is try it and see and listen to the result
Do you have data showing the internal resistance of the coils/inductors as I could see none and such information isn't normally shown
All you can do is try it and see and listen to the result
Do you have data showing the internal resistance of the coils/inductors as I could see none and such information isn't normally shown
as a less expensive 15" woofer option (2 would be ~$120 and give free shipping in the US), this Goldwood pro 15 has a stronger motor with Qts 0.41 and a manageable Le of ~2mH.
oh - it may not be efficient enough for a 7 watt SE amp (?) that's ok for Klipschorn. I've run a B&C with similar mms but stronger motor in a reflex and 200 W would not wake it.
https://www.parts-express.com/GRS-15PT-8-15-Paper-Cone-Prosound-Woofer-3-Voice-Coil-8-Ohm-292-808
oh - it may not be efficient enough for a 7 watt SE amp (?) that's ok for Klipschorn. I've run a B&C with similar mms but stronger motor in a reflex and 200 W would not wake it.
https://www.parts-express.com/GRS-15PT-8-15-Paper-Cone-Prosound-Woofer-3-Voice-Coil-8-Ohm-292-808
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