Hi all,
I have been using ChatGPT to help design a 3 way speaker for a 4w EL84SE amp and a 6w EL34SE Amp.
I have used it to analyse and review various speakers and I am narrowing it down to the following
Woofer: Faital Pro 8PR200 8" 200W 8 Ohm
Technical specifications
https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=101030200
Midwoofer : 6.5” B&C 6MD38
Nominal Impedance 8 Ω
Minimum Impedance 6.5 Ω
Nominal Power Handling 120 W
Continuous Power Handling 240 W
Sensitivity 96 dB
Frequency Range 130 Hz - 6000 Hz
Voice Coil Diameter 38 mm (1.5 in)
Winding Material Aluminium
Former Material Glass Fibre
Winding Depth 9 mm (0.35 in)
Magnetic Gap Depth 6 mm (0.25 in)
Flux Density 1.4 T
Woofer Cone Treatment None
Re 5.7 Ω
Qes 0.49
Qms 3.7
Qts 0.44
Vas 3 dm³ (0.1 ft³)
Sd 132 cm² (20.5 sq²)
η0 1.4 %
Xmax 2 mm
Xvar 4.5 mm
Mms 12 g
Bl 10.5 Tm
Le 0.25 mH
EBP 265 Hz
Cone Shape Exponential
Magnet Material Ferrite
Spider Single
Pole Design T-Pole
Woofer Cone Treatment None
https://www.bcspeakers.com/en/products/lf-driver/6.5/8/6MD38
They are both high sensitive designs and I would be grateful for any views and help on choosing a tweeter or AMT for a ported design and the size of the box.
Thanks
I have been using ChatGPT to help design a 3 way speaker for a 4w EL84SE amp and a 6w EL34SE Amp.
I have used it to analyse and review various speakers and I am narrowing it down to the following
Woofer: Faital Pro 8PR200 8" 200W 8 Ohm
Technical specifications
- Nominal Diameter: 200 mm (8in)
- Overall Diameter: 223.75/207.9 mm (8.81/8.18in)
- Bolt Circle Diameter: 210 mm (8.27in)
- Baffle Cutout Diameter: 183 mm (7.20in)
- Overall Depth: 116.7 mm (4.59in)
- Flange/Gasket Thickness: 10.7 mm (0.42in)
- Impedance: 8 ohm
- Minimum Impedance: 6.4 ohm
- AES Power: 200 W
- Program Power: 400 W
- Sensitivity: 95 dB
- Frequency Range: 70:5000 Hz
- Voice Coil Diameter: 52 mm (2in)
- Voice Coil Material: Al
- Voice Coil Former: Glass Fiber
- Voice Coil Depth: 19.3 mm (0.76in)
- Magnetic Gap Depth: 9 mm (0.35in)
- Surround Type: Triple
- Spider Profile: 1x variable height waves
- Chassis Material: Aluminum
- Magnet Material: Neodymium Ring
- Demodulating Ring: Aluminum Ring
- Flux Density: 1.15 T
- Driver Displacement Volume: 1 L (0.035ft^3)
- Resonance (Fs) - 58 Hz
- DC Resistance (Re) - 5.1 Ohm
- Electrical Q (Qes) - 0.38
- Mechanical Q (Qms) - 9.4
- Total Q (Qts) - 0.37
- Compliance Equivalent Volume (Vas) - 16.9 L
- Diaphragm Area (Sd) - 209 cm<small>2</small>
- Maximum Linear Excursion (Xmax) - 8.15 mm
- Maximum Mechanical Excursion (Xdamage) - 13.5 mm
- Moving Mass - System (Mms) - 27.2 g
- Force Factor (BL) - 11.5 Tm
- Voice Coil Inductance (Le) - 0.55 mH
- Moving Mass - Diaphragm (Mmd) - 23.8 g
- Compliance (Cms) - 0.28 mm/N
- Mechanical Resistance (Rms) - 1.1 Kg/s
- Reference Efficiency (Eta Zero) - 0.84 %
- Efficiency Bandwidth Product (EBP) - 153
https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=101030200
Midwoofer : 6.5” B&C 6MD38
Specifications
Nominal Diameter 170 mm (6.5 in)Nominal Impedance 8 Ω
Minimum Impedance 6.5 Ω
Nominal Power Handling 120 W
Continuous Power Handling 240 W
Sensitivity 96 dB
Frequency Range 130 Hz - 6000 Hz
Voice Coil Diameter 38 mm (1.5 in)
Winding Material Aluminium
Former Material Glass Fibre
Winding Depth 9 mm (0.35 in)
Magnetic Gap Depth 6 mm (0.25 in)
Flux Density 1.4 T
Woofer Cone Treatment None
Parameters
Fs 130 Hz
Re 5.7 Ω
Qes 0.49
Qms 3.7
Qts 0.44
Vas 3 dm³ (0.1 ft³)
Sd 132 cm² (20.5 sq²)
η0 1.4 %
Xmax 2 mm
Xvar 4.5 mm
Mms 12 g
Bl 10.5 Tm
Le 0.25 mH
EBP 265 Hz
Design
Surround Shape Triple Roll
Cone Shape Exponential
Magnet Material Ferrite
Spider Single
Pole Design T-Pole
Woofer Cone Treatment None
https://www.bcspeakers.com/en/products/lf-driver/6.5/8/6MD38
They are both high sensitive designs and I would be grateful for any views and help on choosing a tweeter or AMT for a ported design and the size of the box.
Thanks
Hi,
quick comment on sensitivity and examples how you can navigate bit further by yourself.
Driver datasheet sensitivity number is usually some average on some bandwidth, like around at 1kHz. A 8" driver might have 95dB/1m/1W sensitivity around 1kHz, but really has quite small cone area (Sd) so it just doesn't make much low frequency output without great excursion, which means it needs power, which means 8" drivers aren't high sensitivity at bass. If you want your system have a ~flat frequency response, the sensitivity needs to be high at the lowest frequency you want from your system.
Factor in "bafflestep loss" and the 95dB datasheet sensitivity of 8pr200 "at bass" is something like 85dB/1W/1m or less in reality, depending what's the tuning of the ported box you have for it. In a closed box sensitivity is really down. You could use 4x 8" drivers to ramp the sensitivitity up by ~6dB at any particular low frequency.
6W of amplification is about 8dB over 1W, so a 85dB / 1w / 1m sensitive full bandwidth system could reach ~93dB maximum output around 40-60Hz at max power at 1m. If you wish ~clean dynamic headroom of say 15db and compensate for listening distance of say 2m (6dB), average listening level would be around ~70dB at the listening spot. This might be plenty for many, but it's hardly a high sensitivity system.
Usually sound is mixed about at 80dB average level, because hearing system is most linear there, and thus ought to be target capability of any serious playback system as well. Add in the 2m listening distance and 15dB dynamics you are looking at about 100dB max capability from a system at minimium, which means for 6W amp you need the system sensitivity somewhere 95dB/1W/1m for the whole bandwidth, starting from the low bass. A 15" bass close to wall might have it, 8" midrange perhaps.
In general, if you want high +90dB/1m/1W sensitivity system look for something like 15" bass in a ~150 litre box. Or even better, try to measure how loud you want to listen and figure out what is actually needed to reach that with your amplifier.
Have fun with your project!🙂
ps. don't trust blindly on the chatGPT, this is quite narrow domain stuff so it starts to go wrong quite fast if you start asking follow up questions.
quick comment on sensitivity and examples how you can navigate bit further by yourself.
Driver datasheet sensitivity number is usually some average on some bandwidth, like around at 1kHz. A 8" driver might have 95dB/1m/1W sensitivity around 1kHz, but really has quite small cone area (Sd) so it just doesn't make much low frequency output without great excursion, which means it needs power, which means 8" drivers aren't high sensitivity at bass. If you want your system have a ~flat frequency response, the sensitivity needs to be high at the lowest frequency you want from your system.
Factor in "bafflestep loss" and the 95dB datasheet sensitivity of 8pr200 "at bass" is something like 85dB/1W/1m or less in reality, depending what's the tuning of the ported box you have for it. In a closed box sensitivity is really down. You could use 4x 8" drivers to ramp the sensitivitity up by ~6dB at any particular low frequency.
6W of amplification is about 8dB over 1W, so a 85dB / 1w / 1m sensitive full bandwidth system could reach ~93dB maximum output around 40-60Hz at max power at 1m. If you wish ~clean dynamic headroom of say 15db and compensate for listening distance of say 2m (6dB), average listening level would be around ~70dB at the listening spot. This might be plenty for many, but it's hardly a high sensitivity system.
Usually sound is mixed about at 80dB average level, because hearing system is most linear there, and thus ought to be target capability of any serious playback system as well. Add in the 2m listening distance and 15dB dynamics you are looking at about 100dB max capability from a system at minimium, which means for 6W amp you need the system sensitivity somewhere 95dB/1W/1m for the whole bandwidth, starting from the low bass. A 15" bass close to wall might have it, 8" midrange perhaps.
In general, if you want high +90dB/1m/1W sensitivity system look for something like 15" bass in a ~150 litre box. Or even better, try to measure how loud you want to listen and figure out what is actually needed to reach that with your amplifier.
Have fun with your project!🙂
ps. don't trust blindly on the chatGPT, this is quite narrow domain stuff so it starts to go wrong quite fast if you start asking follow up questions.
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I'm not sure I'd use either of those with typical modern AMT's. The breakup region on both midranges is relatively low in frequency. Many AMT's don't like being played too low either, so you're going to have to pick carefully and/or get creative with your crossovers. With steep enough slopes or notch filters in problem areas you may be OK, but I'm not sure it's going to be a straightforward/easy ride. If you like a challenge or don't have extreme audiophile tendencies you may also be fine.
Pro style midranges often get paired with compression/horn tweeters, which are typically OK crossed in the 1500-2000 Hz range and often have excess output around the cross point, so they aren't working as hard there once equalized down. For home audio use some cross compression drivers even lower.
Pro style midranges often get paired with compression/horn tweeters, which are typically OK crossed in the 1500-2000 Hz range and often have excess output around the cross point, so they aren't working as hard there once equalized down. For home audio use some cross compression drivers even lower.
And I totally missed that your intention for the 3-way was to use those two woofers together. Sorry for the confusion.
You didn't mention a price range, so I'm going to throw this first one out there. It's an AMT with a suggested minimum cross point of 1 kHz at 12 dB/octave and has 102 dB sensitivity, so output should keep up with anything you want to do in the midrange/bass. With a cross point that low, you should also be OK with many pro style midbasses/midranges. It's not cheap though.
https://www.beyma.com/speakers/Fichas_Tecnicas/beyma-speakers-data-sheet-amt-TPL150H.pdf
On the more affordable front, this waveguide from Joseph Crowe should let the AMTPRO-4 go down to around 1.5 kHz, but sensitivity is more like 94 dB, and you'll need to print the waveguide if you want to keep the price down. The first link would just get you the files to 3D print, not the physical waveguide.
https://josephcrowe.com/products/waveguide-no-1905-for-dayton-amtpro-4-tweeter
https://josephcrowe.com/blogs/news/horn-no-1905
https://www.parts-express.com/Dayton-Audio-AMTPRO-4-Air-Motion-Transformer-Tweeter-275-094
https://www.beyma.com/speakers/Fichas_Tecnicas/beyma-speakers-data-sheet-amt-TPL150H.pdf
On the more affordable front, this waveguide from Joseph Crowe should let the AMTPRO-4 go down to around 1.5 kHz, but sensitivity is more like 94 dB, and you'll need to print the waveguide if you want to keep the price down. The first link would just get you the files to 3D print, not the physical waveguide.
https://josephcrowe.com/products/waveguide-no-1905-for-dayton-amtpro-4-tweeter
https://josephcrowe.com/blogs/news/horn-no-1905
https://www.parts-express.com/Dayton-Audio-AMTPRO-4-Air-Motion-Transformer-Tweeter-275-094
I've been messing around in the various AI foundation models (chatbots). They benefit from human feedback reinforcement learning (HFRL). If you ask the LLM a question and it gives a wrong answer you can explain why the answer is wrong and it will incorporate that into its model. For example, I asked it to do some loudspeaker calculations and it spit out a wrong answer because it was doing metric to imperial conversions right in the middle of performing the calculations. I told it not to do that and it obeyed. If enough users point things out like that the model will eventually adjust for everyone else and become more reliable.
Open AI and Anthropic seem to be the best at loudspeaker questions right now. Google Gemini is weaker, but Gemini gives the impression it is better at receiving HFRL so maybe it will pass the other two in the near future.
It's too bad that the people here who are really good in this knowledge domain aren't pounding away at the chatbots with beginner level questions. Obviously, they wouldn't do that because it's boring to them. But expert HFRL when the chatbots spit out wrong or misleading answers improves the LLMs for everyone.
Open AI and Anthropic seem to be the best at loudspeaker questions right now. Google Gemini is weaker, but Gemini gives the impression it is better at receiving HFRL so maybe it will pass the other two in the near future.
It's too bad that the people here who are really good in this knowledge domain aren't pounding away at the chatbots with beginner level questions. Obviously, they wouldn't do that because it's boring to them. But expert HFRL when the chatbots spit out wrong or misleading answers improves the LLMs for everyone.