DIY Audio Projects Forum
 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

DIY Audio Projects Forum

Welcome to the DIY Audio Projects Message Forum. Use these forums to discuss Hi-Fi audio and to share your DIY Audio Projects. Registration is free and required to post messages and view the file attachments. Registration will only take a minute and registered users do not see any advertisements. After you have completed the online registration process, check your email (including spam/junk folder) for the verification email to activate your account. New members are under moderation - so your posts will not be visible until approved by a moderator. See the Read Me 1st, Forum RULES and Forum FAQ to get started on the forum.

It is currently 12 May 2021, 12:25

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 5 posts ] 
Author Message
PostPosted: 11 Apr 2021, 23:32 
Offline

Joined: 10 Apr 2021, 05:18
Posts: 2
Hello everyone, I need some expert advice.

I’m halfway through making a portable speaker with component car audio speakers and a chip amp. (In an undersized enclosure). The bass is very poor, leaving me wondering whether to complete the project, change direction, or abandon ship and buy a consumer bluetooth speaker/s instead.

I suspect both the amp and the speakers that I have are weak in producing bass.

Speakers: JBL GTO608C components with standard external crossovers. https://www.amazon.com.au/JBL-GTO608C-6 ... B0024JARH6
https://www.elite-electronics.com.au/In ... t_Speakers

Amp:TPA3116D2 premade board.
https://www.ebay.com.au/itm/100WX2-Blue ... 2791480062

Power supply: 18v drill battery or 12v AC adapter

I should mention I’m not always using super clean studio music, like most users, but some crowd recordings of live concerts and also many gospel and church service recordings from decades ago, some of which have their origins in reel-to-reel recorders. This is the reason for wanting headroom, not a just-enough kind of solution. However, I have plenty of studio music and other playback devices (audio in my car, home theatre, Samsung Galaxy Buds+) to know the speaker issue is nothing to do with my audio files.

So my questions to all the much more experienced tinkerers out there:

1. Will any system using just these speakers, be able to produce reasonable bass? If I’m wasting my time, I’ll just pull out now.
2. If so, can someone point me in the right direction of the best enclosure type (sealed, ported) and volume per speaker? I’ll just make something from 9mm or 12mm MDF, and I have access to a water jet profile cutter at work to make curves, etc as needed.
3. Could I make this work by adding passive radiators?
4. Alternatively, I could change my amp for a similar one with a 2.1 setup for a subwoofer?
5. I’m aiming for something with more volume and soundstage than something like an Ultimate Ears Megaboom 3, or maybe a pair of JBL Flip 5’s. I would have thought that the 162mm speakers with separate tweeters surely should have more potential than the 50mm drivers in these consumer units, but new tech can be surprising.
So if something like a megaboom 3 will perform better, I'll just do that.

Many thanks!


This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.



Top
 Profile  
 
PostPosted: 12 Apr 2021, 22:01 
Offline

Joined: 13 Jan 2018, 21:33
Posts: 407
Location: australia
I found the following specs for the bass unit. http://www.cieri.net/Documenti/JBL/Car% ... 0box%20etc.).pdf
Looks like the Fs is about 70 hz and Vas is 8.5 litre. You could try inputting these T/S parameters into an online enclosure calculator such as http://www.mh-audio.nl/Calculators/Refl ... lator.html (there are many) to have a look at modelled frequency response and vary the enclosure size and test the one you have designed. As built designs in your own room may respond differently to your model of course. I use a 180mm/6.5in driver in a 15 litre enclosure and am happy with bass output. The Vas is higher but I accept the compromise. It will get asthmatic before the church organ gets to the low notes but I don’t have enough room for an 500mm woofer in a refrigerator size enclosure.

_________________
John


Top
 Profile  
 
PostPosted: 13 Apr 2021, 20:01 
Offline

Joined: 10 Apr 2021, 05:18
Posts: 2
Thanks Woodo for your reply.
Especially grateful for tracking down those specs as I had searched and been unable to find that data.

That calculator you've linked suggests a 73 litre enclosure.

Another calculator, at the link below, wouldn't accept a Qts above 0.707 but when I increased my target Qtc to 0.95 (to be more than the speakers' Qts of 0.907 as the calculator demanded) it suggested a 56 litre enclosure.
https://www.diyaudioandvideo.com/Calcul ... Enclosure/

I'm guessing this is because the speaker is an aftermarket car audio speaker and thus designed for an unsealed car door.

Would I be correct in concluding that a well-sealed enclosure as large as practical (for example, 6 litres) with ample polyfill, is my best option?


Top
 Profile  
 
PostPosted: 15 Apr 2021, 22:29 
Offline

Joined: 13 Jan 2018, 21:33
Posts: 407
Location: australia
Not sure what to advise. If you have the option you may be best to search for drivers that suit the box volume available. This may turn out to be a smaller driver. For instance I have a B&W A5 which look like it has 2 of 80 or 100 mm drivers in a small ported enclosure, specs say it has tweeters too. Can’t be more than 10 litres. It has an internal class d and has airplay connectivity. I just have this for background listening. I am amazed by the bass output. Feels like about 40 hz. I suspect it might be similar to one of those Texas Instruments designs that uses circuitry to represent lower frequencies that it can’t actually produce. Maybe that is an option too? https://www.ti.com/audio-ic/amplifiers/ ... ducts.html

_________________
John


Top
 Profile  
 
PostPosted: 16 Apr 2021, 16:53 
Offline

Joined: 13 Jan 2018, 21:33
Posts: 407
Location: australia
Interesting thread on using foam core for speaker enclosures purportedly with good enough results. May help with fine tuning your enclosure before committing to a permanent solution.
https://www.diyaudio.com/forums/full-ra ... sures.html

_________________
John


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 9 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
DIY Tube Projects :: DIY Tube Amp Kits :: DIY Speaker Projects :: DIY Solid State Projects :: DIY IC / Op-amp Projects :: DIY Phono Projects :: DIY Cable Projects :: Hi-Fi Audio Schematics
© diyAudioProjects.com - Terms of Service - Privacy Policy