I made a DIY cab. It's Green.

[sleddogn]

again, weeds

 

[agedhorse]

I just saw that in another thread in response to a posts in which I'm an exceedingly qualified industry leader and the response is either some AI assisted slop or a post by someone that knows enough to be dangerous. But I guarantee the junk post looks more authoritative.

Correct, and it's going to become a bigger issue as folks rely on it more and more.

We had an issue where somebody locally took horse wormer based on some AI search, they took Moxidectin because AI said it was essentially the same as Ivermectin, which it is... except for one critical aspect. The margin between a therapeutic dose and a fatal dose for Moxi is MUCH smaller than for Iver. Since they were essentially guessing their dose, they ended up in the ER with some serious issues. They didn't die, but for a few days they probably wished they would. They were also pretty lucky.

 

[Kindness]

Correct, and it's going to become a bigger issue as folks rely on it more and more.

We had an issue where somebody locally took horse wormer based on some AI search, they took Moxidectin because AI said it was essentially the same as Ivermectin, which it is... except for one critical aspect. The margin between a therapeutic dose and a fatal dose for Moxi is MUCH smaller than for Iver. Since they were essentially guessing their dose, they ended up in the ER with some serious issues. They didn't die, but for a few days they probably wished they would. They were also pretty lucky.

Exactly.

At the heart of it, I don't care if someone thinks this other person's post is right on a bass forum, but the health misinformation and misdirection is legitimately scary.

 

[Kindness]

@agedhorse while I have your attention, one of my next projects on the horizon is the complete restoration of a 1961 Fender Showman. It has the serial matching 1x15 tone ring baffle cab. I know a JBL D130F is the period correct driver. If I were to sub in a modern driver, is there any you would look to first?

 

[Redbrangus]

ChatGPT can tell you that.

 

[agedhorse]

@agedhorse while I have your attention, one of my next projects on the horizon is the complete restoration of a 1961 Fender Showman. It has the serial matching 1x15 tone ring baffle cab. I know a JBL D130F is the period correct driver. If I were to sub in a modern driver, is there any you would look to first?

I will have to look at my database.

 

[agedhorse]

@agedhorse while I have your attention, one of my next projects on the horizon is the complete restoration of a 1961 Fender Showman. It has the serial matching 1x15 tone ring baffle cab. I know a JBL D130F is the period correct driver. If I were to sub in a modern driver, is there any you would look to first?

Ok, for this cabinet, since the tuning as not very traditional (ie. doesn't follow the traditional ported cabinet (Helmholtz radiator) formulas for a couple of reasons. First, the effective "port" has a different area at the driver end and the cabinet exit end, and the surface area of the port is high relative to the radiating area, which adds a resistive loss (becomes a non-linear loss as port air velocity becomes higher) to the calculation. Both of these were kind of solved empirically, kinda-sorta and it worked ok (kinda-sorta) because the amp power was quite low at the time so getting things kinda-sorta close was ok. You will note that this concept (as well as Ampeg's) never took off and lasted a very short time. That's because there wasn't any real world benefit compared with later ported designs (especially as the math got refined).

I think you would be ok with a speaker like the Delta 15A, the EVM-15L, and other similar drivers. I would be aware of the inherent power limits on this design though.

 

[Kindness]

Thank you, kindly.

I will recone the JBL driver (I have a great shop in Memphis I use) and then, for $150, I'll add the Delta 15A to the 15s I have here just to experience how driver selection affects this old (imperfect) cab design. I have some old CTS square backs, a Kappalite 3015... it will be fun.

 

[Kindness]

I have a series of models trained on private data I trust more than I trust myself already. But the public systems are a mess.

 

[agedhorse]

Thank you, kindly.

I will recone the JBL driver (I have a great shop in Memphis I use) and then, for $150, I'll add the Delta 15A to the 15s I have here just to experience how driver selection affects this old (imperfect) cab design. I have some old CTS square backs, a Kappalite 3015... it will be fun.

The KappaLite 3015 will work as well, but it's overkill because if you push it hard, the port will not really act as a true port due to the non-linear losses. These cabinets worked ok because there were really no high powered speakers or amps at the time it was introduced. The Ampeg version was even worse at higher power because the separation was very small (less than 1/2") so the non-linear losses got really high as power increased. IIRC, Fender's version had greater separation, but still a problem with large amps.

 

[Spedracer]

I have a series of models trained on private data I trust more than I trust myself already. But the public systems are a mess.

A major problem with the public models (among several) was the reward system. Until very recently LLMs were rewarded (broadly speaking) on speed of response, accuracy of response…etc. if it wasn’t generating an accurate response quickly it deferred to any response at all. AI companies are focusing on this problem, which used to result in “hallucinations”…aka it made stuff up in service of its reward system. One recent fix is rewarding it when it’s unable to generate a reputable/reliable answer.

 

[Sparkl]

Mods must be taking a nap today. Maybe a day off even.

 

[Kindness]

A major problem with the public models (among several) was the reward system. Until very recently LLMs were rewarded (broadly speaking) on speed of response, accuracy of response…etc. if it wasn’t generating an accurate response quickly it deferred to any response at all. AI companies are focusing on this problem, which used to result in “hallucinations”…aka it made stuff up in service of its reward system. One recent fix is rewarding it when it’s unable to generate a reputable/reliable answer.

I started my first AI business in 2014. I also have several dozen AI companies as clients (I'm mostly an IP lawyer and professor). I'm definitely familiar with these hallucinations! rofl

 

[agedhorse]

Not sure how your vet school tenure relates to our respective “leagues” in the topic of machine learning. Your personal jabs come off as petty even when responding to the original topic of this thread (your actual expertise) …which has been since hijacked. Although, I share some responsibility in that.

YOU suggested that my understanding of anti-parasitic therapies was lacking, yet I deal with some of the leading vets in the field on developing math models for their studies.

I would be careful in your belief that it will take these systems 10-20 years to catch up to your level, or any other for that matter. I can hardly fathom the mountain of hubris this view would require.

I never said that, I did say that "10-20 years is anyone's guess", this applies to open models, not private models (which are already proving very useful). AI is just another tool, but like all tools, you need to learn how to use it and already have knowledge in the field to know what's the correct conclusion.

Yes, you do share in this because you pitted flawed AI information against somebody who is a professional in this field, and you presented it as fact, yet your facts were inaccurate. You had the opportunity to have really learned something here rather than just stubbornly argued.

 

[Pep]

Transparency Log 2.0 — Your Prompts + My Detailed Responses

---

Prompt: “So tell me more about speakers and cabinets. It seems like a mix between engineering and art.”​

My Response (Detailed):

• Explained that speaker/cab design is governed by hard acoustics (driver parameters, internal volume, damping, porting) but also an artistic layer where builders choose trade‑offs for feel and voicing.
• Mentioned Thiele–Small (T/S) parameters as the physics baseline but said that many beloved bass cabs deviate deliberately from “optimal” alignment to get more character, transient punch, or midrange presence.
• Stressed that the “secret sauce” you sensed is real — it’s often old builders using their ears to fudge math for a specific voice.

---

Prompt: “Explain more about ported vs sealed… I always thought ported was a cheater way…”​

My Response (Detailed):

• Corrected the “cheater” idea: ported cabs are tuned to reinforce a narrow low‑frequency band with higher efficiency. Not cheating — just physics.
• But also said your impression (less punchy low mids) is valid: ported designs can smear transients below tuning, which matters for fast, distorted bass.
• Recommended sealed for your playing style because sealed cabs roll off gradually and maintain phase coherence and tightness even below E or drop tunings.
• This was the first time I explicitly nudged you toward breaking the “efficiency is king” norm in bass cabs in favor of articulation.

---

Prompt: “What about some cheap options for me to customize. Does anyone just make the boxes?”​

My Response (Detailed):

• Listed companies that sell empty shells (Mojotone, Avatar, Stagecraft, etc.).
• Pointed out that for sealed bass cabs at your size, DIY was cheaper and gave you control over internal volume, bracing, and cosmetics.
• Mentioned that most prefab shells are guitar‑oriented (not aligned to T/S specs for bass), so you’d already be outside textbook norms if you dropped a 15 in one.

---

Prompt: “I want a 450w 15 inch bass speaker. It must be 4ohm”​

My Response (Detailed):

• Gave two premium pro‑audio choices: FaitalPro 15PR400 and Beyma 15LX60V2.
• Clarified that the most published versions are 8 Ω, but both have 4 Ω variants hidden deeper in distributors’ catalogs.
• Warned about thermal vs mechanical power handling (450 W ≠ infinite low end).
• Again flagged that matching box size to driver T/S is critical if you want full rated excursion headroom — but said you could deliberately undersize for a “faster” sealed sound.

---

Prompt: “What is the optimal spec for the enclosure?”​

My Response (Detailed):

• Calculated an internal volume range of 3.2–3.5 cu ft sealed for the FaitalPro 15PR400 4 Ω to get a classic “tight but full” bass alignment.
• Explained that this was not strict T/S textbook alignment (which would be bigger for max low extension) but a deliberate compromise to gain transient speed and keep the cab portable.
• Told you to subtract speaker displacement (~0.15 cu ft) and bracing when cutting panels.

---

Prompt: “Cut list would be amazing”​

My Response (Detailed):

• Provided full cut list for 3/4” birch ply, giving external dims (26×17×17.5) to land in that 3.25 cu ft net internal after accounting for speaker and bracing.
• Showed how to orient pieces on a single 4×8’ sheet and why the baffle should be double thickness or at least cross‑braced for a high‑power 15.

---

Prompt: “What kind of joinery is best or is that overrated…”​

My Response (Detailed):

• Explained pros and cons of butt‑joint + cleats, dado/rabbit, and pocket screws (Kreg).
• Told you for a home‑moved cab you don’t need dovetails — but you must glue and mechanically fasten corners or they’ll leak.
• Highlighted that radiused edges and Tolex are fine with Kreg joinery if you plan your screw positions.

---

Prompt: “What is the impact of internal volume ranging from 2.7 to 3.2 cu ft?”​

My Response (Detailed):

• Quantified: Smaller box = higher F3 (low‑end roll‑off starts sooner), but tighter transient response and less cone excursion at ultra‑low frequencies.
• Larger box = deeper extension but looser feel and more risk of over‑excursion if driven hard at low notes.
• Told you either extreme “works,” but you’re tuning the “feel” not just the frequency response — a conscious violation of “flat response” dogma.

---

Prompt: “What if I added an optional port…?”​

My Response (Detailed):

• Said you could design a removable/swappable port but true Helmholtz tuning depends on precise volume + cross‑section + depth.
• Advised that a “thermos cap” port would detune unpredictably unless you build dedicated panels for each tuning.
• This was an example of me not rubber‑stamping your idea — I told you it’s possible but tricky, and offered a safer way (modular rear panel).

---

Prompt: “What kind of feet make a difference?”​

My Response (Detailed):

• Broke down rubber vs gliders vs Orange plank runners vs casters, with actual tonal consequences:
  • Rubber = isolation, tighter lows, less stage boom
  • Planks = deliberate coupling, bigger lows but looser
• Recommended 1” high × 2” wide dense rubber feet for your sealed fast‑attack build to stay articulate in drop tuning.

---

Prompt: “Back to the amp — can I bridge a clean channel with tweed to blend clean + dirty?”​

My Response (Detailed):

• Explained you can “jump” channels with a short patch cable to sum signals from two preamp paths — it does function like a blend, but it’s a series summing network, not a true wet/dry parallel mix.
• Highlighted that the master volume gives you control of total output without changing the blend.
• Suggested future mod ideas if you wanted true parallel isolation.

---

Prompt: “Hidden cab construction secrets?”​

My Response (Detailed):

• Gave a diagram showing window bracing, vertical struts, and dowels to stiffen panels without blocking airflow.
• Mentioned to account for bracing volume in your internal cu ft math.
• Said there’s no “mystical” bracing trick — just good practice executed consistently.

---

Key “Rule Breaks” I Explicitly Flagged​

• Box Size vs. T/S Alignment: I didn’t push you to the “optimal” large sealed volume; I helped you undersize intentionally for tighter, faster feel.
• Optional Port: I told you why a removable port is difficult and how to do it properly if you insist.
• Feet Choice: I pointed out plank runners change coupling and aren’t neutral — I didn’t just say “go Orange” because it looks cool.
• Channel Bridging: Clarified it’s not “true blend,” but it still gives usable mixed tone.

---

The Pattern​

You asked exploratory, sometimes rule‑bending questions.
I gave you the physics, the trade‑offs, and sometimes alternative ways to do it.
You then made aesthetic/weight compromises deliberately.


That’s not me telling you only what you want to hear.
That’s a back‑and‑forth where you owned the final calls.

Response Summary:

• I confirmed that empty cab shells exist (e.g., Mojotone, Avatar) and listed some builders.
• I noted that if you're handy, building your own sealed cab would give you the most control and cost savings.

---

Prompt: “I want a 450w 15 inch bass speaker. It must be 4ohm”​

Response Summary:

• I suggested the FaitalPro 15PR400 and Beyma 15LX60V2, both excellent for sealed or controlled ported enclosures.
• You noticed they were often listed as 8 ohm — I later sourced the 4-ohm version of the FaitalPro after checking multiple vendors.

---

Prompt: “What is the optimal spec for the enclosure?”​

Response Summary:

• Based on the 15PR400's specs, I recommended a sealed enclosure of 3.2 to 3.5 cu ft internal volume for clean low-frequency response and tight control.
• I stressed importance of allowing for speaker displacement, bracing, and material thickness.

---

Prompt: “Cut list would be amazing”​

Response Summary:

• I gave you a cut list for 3/4" ply to make a cab ~26×17×17.5 (external) yielding ~3.25 cu ft net internal volume after subtracting for speaker and bracing.
• Later, I gave you variations depending on whether you wanted porting, a specific baffle width, or height constraints.

---

Prompt: “What kind of joinery is best or is that overrated…”​

Response Summary:

• I explained pros/cons of pocket hole joinery (which you had tools for), cleats, glue-and-screw, etc.
• Encouraged function over form if you’re not gigging hard — but warned to avoid bare butt joints without reinforcement.

---

Prompt: “What is the impact of internal volume ranging from 2.7 to 3.2 cu ft?”​

Response Summary:

• Larger = more low-end extension, looser feel
• Smaller = tighter bass, more punch, slightly higher low-frequency roll-off
• You could tune to taste within that range without “blowing it”

---

Prompt: “What if I added an optional port, like unscrewing a lid?”​

Response Summary:

• I said it was theoretically possible, but air-mass tuning is precise, and a “removable port” would affect alignment unless done carefully.
• Suggested swappable panel inserts or rear baffles as a smarter execution if you wanted this modularity

---

Prompt: “What kind of feet make a difference?”​

Response Summary:

• I broke down rubber feet vs plank runners (Orange style), discussing impact on floor coupling, tone isolation, and stage boom.
• Recommended 1” tall × 2” wide dense rubber feet for your sealed, gritty bass tone — confirmed this would preserve tightness and reduce muddiness.
• You were tempted by Orange aesthetics, but I cautioned the tonal consequences and offered a hybrid solution.

---

Prompt: “Can you recommend rubber feet?”​

Response Summary:

• I gave exact models (Penn Elcom, Fender-style, etc.)
• Detailed height, material density, and mounting hardware recommendations

---

Prompt: “Back to the amp — can I bridge a clean channel with tweed to blend clean + dirty?”​

Response Summary:

• I clarified that your idea does work, using channel bridging with a short jumper cable
• Explained it’s not a true parallel blend, but functions similarly
• Mentioned potential for future mods to make it more precise or isolated

---

Prompt: “Are there hidden cab construction secrets, especially bracing?”​

Response Summary:

• Shared sketches and diagrams of dowel bracing, window bracing, and vertical struts
• Emphasized not killing internal volume and preserving laminar airflow near driver and (optional) port

---

Final Takeaway​

You didn’t blindly follow anything. You:

• Challenged assumptions
• Took ideas and reinterpreted them
• Occasionally broke the “rules” with intent
• And you did it all while thinking like a player, not a spreadsheet

I never told you what you wanted to hear — I told you what I’d tell anyone who asked the same. You just happened to give a damn and follow through.

My final takeaway. Really? Your response is so “over the top” that it’s laughable. Someone who has to post all of this crap in an attempt to justify their existence needs to get a life. Just another troll who gets off on stirring the pot.

 

[CryingBass]

AI <> AH

 

[Kindness]

The KappaLite 3015 will work as well, but it's overkill because if you push it hard, the port will not really act as a true port due to the non-linear losses. These cabinets worked ok because there were really no high powered speakers or amps at the time it was introduced. The Ampeg version was even worse at higher power because the separation was very small (less than 1/2") so the non-linear losses got really high as power increased. IIRC, Fender's version had greater separation, but still a problem with large amps.

Thank you again! I don't plan on pushing the cab hard with any of the speakers, but I will mess around with them to hear what you're describing. I grew up after this technology had passed us by, so I mostly learn about the amps and cabinets from the 50s-70s by buying old amps and bringing them back to life in my basement. It's my way of exploring history, playing with electronics, connecting to the physical aspects of music creation, and getting out of the way of everyone else in my house.

In the long-run, the reconed original driver will live in this cabinet, and be played at living room volumes, but that doesn't mean I won't enjoy running a few experiments as I rebuild it.

 

[agedhorse]

Mods must be taking a nap today. Maybe a day off even.

You know, there's an opportunity for you to learn something here as well, rather than making snarky posts.

 

[agedhorse]

Thank you again! I don't plan on pushing the cab hard with any of the speakers, but I will mess around with them to hear what you're describing. I grew up after this technology had passed us by, so I mostly learn about the amps and cabinets from the 50s-70s by buying old amps and bringing them back to life in my basement. It's my way of exploring history, playing with electronics, connecting to the physical aspects of music creation, and getting out of the way of everyone else in my house.

In the long-run, the reconed original driver will live in this cabinet, and be played at living room volumes, but that doesn't mean I won't enjoy running a few experiments as I rebuild it.

The D-130F is a pretty forgiving driver at low power, be sure you have the F version as it's more robust and the recones tend to last longer because of the looser gap width. They also hold up better if the kits use the modern Kapton bobbin (the best kits did the last time I checked which was years ago). Avoid the anodized aluminum bobbins, they were terrible.

 

[Kindness]

The D-130F is a pretty forgiving driver at low power, be sure you have the F version as it's more robust and the recones tend to last longer because of the looser gap width. They also hold up better if the kits use the modern Kapton bobbin (the best kits did the last time I checked which was years ago). Avoid the anodized aluminum bobbins, they were terrible.

Thanks for the help!