The Tube Doctor

Damn shame I can't persuade Howard Doctor to participate in these forum discussions.
He could certainly add a tremendous amount of knowledge & myth-busting to these
proceedings!

fresh1

iTrader: (2)

The same thing that a rural fire service has to do with electrical engineering you douchebag.

dogbaker

Morels:

Fine stuff - I have sold Morel and used their speakers in my own vehicles. I have always been able to produce some solid sound stages with their stuff, and I have personally loved their tonality. I am quite sure that you won't be disappointed, if you decide to run with any of their offerings.

dogbaker

So you do realize that you're literally saying nothing here -?

As in your past experiance / title has nothing to with engineering - which you originally claimed it did.

It might help if you got off the pipe!

Next!

dogbaker

Indeed - but he probably knows a turkey shoot when he see's one!
-doc and i know each other.

PS - I will be sending you a PM...

dogbaker

Okay - so moving on - I am going release a post on SQ system design, starting with the Power Supply elements - stay tuned if you like and if not ciao...

I will release it later tonight...

fresh1

iTrader: (2)

Let me clarify, you mentioned rural firefighting in a car audio thread, particularly in direct response to a post regarding electrical engineering. Then you listed some names of people who have all played a role in car audio, one happened to be named Liddell. This is why I said I would take a page out of your book and do what you did with the firefighting thing and mentioned Chuck Liddell, and even then, if I'm not mistaken, MTX, a car audio company, sponsors some fighters. Not sure how many fires are involved in car audio, unless its because of a natural disaster or user error. That's all. Anyways, I'm done. If you ever get around to putting a tapped horn in a car with a 3 dollar 6.5'' and 200 watts that sets an SQ record thanks to your super crossovers to make it sound like a 25 dollar speaker while hitting 150 db's, which I'm sure Danley can do, let me know.

Dukk

Thanks for the response. To be clear, I have not let you stay - so far you have not given me reason to help you leave. There are many people on here, some I agree with and get along with, some I do not, most don't pop up on my radar as they are everyday members enjoying our community. Everyone has a right to their opinion and voice - at least until it runs contrary to the rules or my admittedly eclectic personal value system. I try to find value in all our members.

I believe you want to be part of our community or you would not have joined. Within our community there are many levels of members right from the greenest noob to some pretty high level industry members and competitors. As with any new member in any community, there is going to be a period of time where people will evaluate their input and decide for themselves if the member knows their stuff, is full of , or is a moron. We have had various levels of all three of these over the years that have all vehemently defended themselves as an authority so please forgive those that may be 'testing' you. This is where my thought that if we had a name that others could potentially verify as a legitimate resource that it might save you some greif.

For example - anonymous member comes on and says Speaker A is their new reference standard. Why should anyone care?

Now, Mark Eldridge comes on here and says Speaker A is their new reference standard and people will take notice.

Or how about we look at 20-ish years ago. If some random dude had stuck gigantic storage capacitors in their car they likely would have been denied entry into car audio events due to safety concerns let alone anyone taking them seriously. Now change that random dude for Richard Clark and make that car the undefeated SW Grand National and suddenly a whole market for the "Stiffening Capacitor" is born.

Now a more pertinent comparison. Yuli may not, in your opinion, carry a resume of your magnitude but his track record in SPL competition gives him a lot of street cred. If an opinion on a box design was fielded that you and he had polar opinions about, he may well get more support than you do, rightly or wrongly, because people have a developed opinion on Yuli while you are still 'random dude'. You can't fault people for trusting what they are comfortable with compared to something unfamiliar. People will develop their opinion of you over time but it is unfair to demand instant credibility while maintaining anonymity.

Rightly or wrongly, often a name goes a long way towards establishing credibility - something that seems to be causing most of the issues in this thread.

Plus I'll admit that I am personally curious

goalie 35

well i have a couple of questions for you..
1.) how does the crossover point in a system affect phase of the drivers at the xover point. how do you correct this.. ex... speaker a xover at 200hz at 12db/oct. hp. speaker b xover at 200hz @12db/oct lp.. is speaker b out of phase with speaker a? how does speaker placement come into play with this phasing correction? does amplitute per speaker play a role? how can we scientifically see the phase relationship between the drivers? what if speaker b was xover at 18db/oct,24db/oct, 36db/oct or even 6db/oct... why i ask is i run a 4 way set up in my car. the xovers are as such..
sub bass 50 lp @36db/oct..
mid bass 63hz-hp @36db/oct and 160hz-lp@12db/oct.
mid range 160hz-hp@24db/oct and 6.6k-lp@24db/oct.
tweets 6.6k-hp@12db/oct and no limit to upper spectrum..
tweets and midrange are on the same plane one inch apart.
mid bass is in kick panels in aperiodic sealed chamber.
subs in trunk in 3rd order box.. running 1ohm at 3000watts rms..
2.) only read up to page ten of this bitch fest.. but with the tapped horn box... how does spl compression on the driver affect its performance once the inside of the car gets some serious inside pressure.. ex.. interior psi reaching 30-40psi..... thats got to affect the perormance of this design.. now with ported, trial and error, and lots and lots of results.. we can tell how driver a in box a will work in car a to a fairly accurate # how can the tapped horn design handle this "load" . ps. how is derick lee doing these days or do you speak with him anymore..
g

dogbaker

Linear SQ System Design: Step 1 Determining Available Current & Wattage

This is the first in a series of post pertaining to Linear SQ system design that I will be posting. I will take it slow and easy at the start and pickup momentum as we get past the fundamentals.

It all starts with the vehicles power supply.

Most OEM power supplies can support a mere: 30-40 amps of continuous draw for accessory circuits, which is to say that when all critical OEM systems are running that 30-40amps of headroom remains, for other circuits – these circuits are referred to as accessory (citation MECP Silver Manual).

Using the high side – 40amps, our maximum sustainable wattage production BASED ON 13.8 VDC is 552-Watts (citation James Watt – MECP Silver). MECP also states that we should not allow the peak current demands to exceed the alternators peak output by more than 20% or there will be an exponential increase in premature alternator failure.

Review:

1. A high current device within a circuit cannot sustainably exceed the wattage output of the circuits power supply (more on this to come).
2. If we fail to properly consider the aforementioned elements, the vehicles alternator and battery will suffer premature failure and obviously, various aspects of sound reproduction will also suffer, during times of over current demand.

Moving On:

Armed with this truth, it is our goal to ensure not only quality sound reproduction, but also, long-term full system reliability; we must design a system selecting components (cabling, amplifiers, head unit(s), signal processors, speakers and enclosures) that will permit not only high quality sound reproduction, but do so efficiently, so that the systems usable SPL can reach 115dB, while the vehicle is in transit (more on this later). MECP states that a reference system should be able to average 85-95dB achieving peaks of 115dB, during sessions of SQ measurement (I am sure that you SPL types are laughing at these low numbers).

In SQ systems this can be challenging, as the High-pass speakers contributes to the SPL almost as much as the Low-pass speakers do, and better sounding drivers and amplifiers are typical less efficient than lower fidelity offerings. In SPL and LD (loud) systems the bottom (Low-pass) end definitely leads, and as such, 115dB isn’t even a challenge, and amplifiers and speakers used within such systems, also tend to be more efficient. (More on all of this, later on.)

Review:

1. SQ systems inherently use less efficient components.
2. OEM Vehicle Power Supplies don’t have a lot of extra (accessory) sustainable current output.
3. As system designers, we need to understand a lot more than how to run and terminate wires!

Moving On:

If for whatever reason we aren’t able to develop sufficient usable SPL to a) achieve 115dB or b) achieve a level desired by our customer, we will need to make improvements to the OEM vehicle power supply.

There are three ways to improve the core current producing element of an OEM vehicle power supply – the alternator.

1. Have the current output of OEM increased at your local alternator shop.
2. Replace the alternator with a more powerful one.
3. Add additional alternators.

Unfortunately, batteries are not a sustainable source of current (as we all know) however, adding additional batteries can be of benefit, when implemented as interim current supply banks – which is to say, they are useful in supplying current for short term demands, which exceed what the alternator has available during such an occurrence – more batteries = more headroom - (MECP-Silver).

As alternators are expensive to upgrade, most designers add at least a second battery and up their peak sustainable current score by 20%, to a maximum of 48-amps, which equals the average peak sustainable wattage output, from most OEM power supplies to 662.4-Watts.

Review

1. A vehicle’s only sustainable source of current production is the alternator
2. The only way to increase sustainable current availability is to upgrade, replace or add alternators.
3. A batteries primary function is to start the engine (MECP – Bronze).
4. A batteries secondary function is to supply short term current demands that exceed the OEM power supply (MECP- Bronze).
5. Batteries are useful, but not a sustainable current source, so they are our secondary consideration for upgrade.

So let’s stop here for a day or two, while I field some questions, and add some additional insight and clarifications, relating to the contexts within this post.

After a couple of day’s I will continue. Please note that I will have to share some math and that I will make a decent effort to provide clear step-by-step examples of important calculations... Some Ohms Law!

It will be a natural tendency to get ahead of this progression, by asking questions that I am likely to answer a day or four from now, as we all progress together. Please try not to ask question about aspects that I haven’t fully introduced.

Please read the post twice before asking a question - thank you.

Thank you.