Ampeg Isovent - Jack Plate Circuit Board.

[fdeck]

Just a passing question: Are both drivers in the lower bin working? If one of the two drivers is open-circuit, it would result in greatly different behavior than the design intent.

 

[agedhorse]

Just a passing question: Are both drivers in the lower bin working? If one of the two drivers is open-circuit, it would result in greatly different behavior than the design intent.

Hey Francis, I don't thing we have gotten past "the crossover must be the cause" phase yet

 

[Nicholas Orick]

Just a passing question: Are both drivers in the lower bin working? If one of the two drivers is open-circuit, it would result in greatly different behavior than the design intent.

Both speakers work, they all work.

All four speakers are 16 Ohms, a couple of friends are going to ReWirethe Isovent since I am a bit busy with work, and they have the Jack Plate minus the Crossover, I have fully put the Isovent back together, and later this week I will be taking it to their pllace.

They fully understand what I have been saying to all of you and were are going to ReWire it with a much simpler Wiring Scheme WITHOUT the Crossover.

 

[Nicholas Orick]

No offense meant , but I feel like agedhorse answered your question/concerns already.. maybe a few times now. I think you should maybe try a more... "modern" cabinet, for your needs.
YMMV
IMO
etc..

Here are some "Newer More Modern Cabs".

I am sure I will try, but NOT right at the moment, and I am having fun just playing with the Isovent.

All the cones are 16 Ohms.

T$

 

[Nicholas Orick]

Actually, several of us have said what it isn't and we have also said what we are reasonably sure it is based on experience. Most of use are smart enough to realize that we are rarely 100% sure of anything, hence the reason for not having a 100% guaranteed concrete answer, but some of use are 100% sure of what it's not and you can't even accept this because you don't even try to understand.

Knowing what it isn't is some of the most important and useful information available. When troubleshooting, it's part of a technique called "differential diagnostics". The more you can eliminate, the less there is left that could be the problem. I've spent my entire professional life designing and troubleshooting this kind of stuff, this IS how it's done, and it doesn't matter if it makes you all sad and teary eyed that you aren't getting the information that YOU feel entitled to. Suck it up, troubleshooting is a big boy job that takes a little bit of education and thinking ability to do accurately. The results may not be what your little heart wishes for, the problem has a cause that's unchanged by your wishes, hopes or desires. I would have thought you would have figured it out by now and been a little more appreciative of the help you have been given.

From your comments above, it's clear that you are not listening nor are you comprehending what ANYBODY is saying. Do you have any idea how disrespectful and rude this is to the TB community who was trying to help you?

Yea I know about Trouble Shooting. I used to work on M1 tanks in the Army, and I got pretty good at finding and diagnosing problems with tanks, and previously with computers, so yea I can relate to the disrespect you guys seem to be throwing my way.

You arent the only one who can locate a problrm and fix it.

I have been there many many many times myself.

Anyway a couple of friends are going to ReWire the Isoven WITHOUT the Crossover. From there we will see what we get. If the F Bomb persists then I will begin engaging the solutions you recommend - for example getting a Parametric, Surgically Zeroing on the freq, reducing it, and then "gluing the knobs" permanently in place.

 

[Nicholas Orick]

View attachment 3674717

Very Funny.

.

 

[Nicholas Orick]

View attachment 3674717

I used to work on M1 tanks in the Army.

You should be Thankful it ISN'T a Blind Man Driving a Tank.

 

[Redbrangus]

So.... what point are you trying to convey by publishing all those pics of PA cabs?

 

[Indiana Mike]

I used to work on M1 tanks in the Army.

You should be Thankful it ISN'T a Blind Man Driving a Tank.

Back in the day I was in an Armored Cavalry unit. Ten four.

 

[mexicanyella]

Yea I know about Trouble Shooting. I used to work on M1 tanks in the Army, and I got pretty good at finding and diagnosing problems with tanks, and previously with computers, so yea I can relate to the disrespect you guys seem to be throwing my way.

You arent the only one who can locate a problrm and fix it.

I have been there many many many times myself.

Anyway a couple of friends are going to ReWire the Isoven WITHOUT the Crossover. From there we will see what we get. If the F Bomb persists then I will begin engaging the solutions you recommend - for example getting a Parametric, Surgically Zeroing on the freq, reducing it, and then "gluing the knobs" permanently in place.

It’s about time for the OP to post a no-crossover test update.

 

[mexicanyella]

Don’t get too hung up on the disrespect thrown your way thing; people here generally want to help. But in order for them to be able to do that, their suggestions need to be acknowledged and their diagnostic questions answered. This thread has had some gaps in those respects.

Seems like most are still hanging in; let us know what happens with the no-crossover test.

 

[Redbrangus]

Yea I know about Trouble Shooting. I used to work on M1 tanks in the Army, and I got pretty good at finding and diagnosing problems with tanks, and previously with computers, so yea I can relate to the disrespect you guys seem to be throwing my way.

Presumably you were able to diagnose tank problems because you had a great deal of training and experience that gave you a thorough understanding of the various systems involved. You have evidenced no such knowledge base about the subject of your initial inquiry...in fact, you have shown a considerable lack of it, all while asserting "I know things". (Did this remind anyone else of Fredo Corleone?) And doing a certain amount of your own dis'ing in the process. I for one, am looking forward to the results of your reworking the input connectors.

Also, if you haven't done so already...you can save some weight by taking out the horn and driver combination altogether, but you do HAVE to block the hole up with something solid like a piece of plywood or MDF.

 

[agedhorse]

There's a reason military TSMs are written in a step by step manner, the troubleshooting tree clearly and simply presented.

You follow the tree until you come to the conclusion specified in the manual, nondifferent than following your orders without disrespecting those around you.

There's a reason that free thinking is highly discouraged in the military...

 

[NKBassman]

This thread is an instant classic.... or something. :S
Page 12 and still going. I'm super glad I didn't waste my time reading pages 4-11.

I don't know.

Something is causing the F Bomb and I am curious to know what it is.

I will cross that bridge when I get to it.

.

The something you're so curious about was revealed on Page 1. Literally the first response to your original post, and then subsequently explained.

The crossover operates octaves higher than where you are describing.

One of the "features" of that "technology" is higher sensitivity over a narrow bandwidth which can send as you describe. Especially outside of the design's original intent.

Again, and this justifies repeating, the crossover can't possibly have ANYTHING to do with what you are experiencing because it operates octaves away from where the problem exists.

The crossover has NOTHING to do with where the two low frequency sections combine, they affect the tweeter response only.

The ONLY thing that's common to the problem is the low frequency drivers AND THE CABINET.

This is a known challenge with this type of cabinet design, which is why it's rarely used.

(Is this a clear enough explanation?)

Since your understanding of the theory is incorrect, your conclusion is equally incorrect. You could REMOVE the freekin' crossover board and the problem would still remain. In fact, you have essentially done exactly this by disconnecting the tweeter.

May I respectfully suggest that you are creating wild hypothesis without understanding the theory behind what you are saying. By chance did you read this on some website?

This is an unfortunate byproduct of this type of design, which has some benefits also has some rather crippling faults as well. It was a good idea in theory but didn't translate well to good results in practice. It was also quite heavy.

I did investigate a variety of approaches like this many years ago, I ended up with a blended manifold design that was a hybrid, and even that required a waveguide and phase coherency adjuncts to work well. It was a pro audio product that worked pretty well but even so couldn't overcome the drawbacks of linearity, cost and weight. It did improve sensitivity, and it sold ok, but it wasn't good enough to survive the competitive nature of the industry.

The drivers themselves have resonance in free air (Fs) and if the Q of the resonance is high enough, the sensitivity peak at resonance can be objectionable.

I suspect based on what I recall about this approach, is that the combination of Fs and the resonance of the enclosure result in higher sensitivity at the system resonance (which is the product of combining Fs with enclosure) and in fact there may be 2 or more resonance peaks given that there are more than 2 resonance modes in that approach.

Since the crossover has NOTHING to do with the drivers (in fact I believe it's nothing more than a straight wire between the input jacks and the LF drivers), it doesn't even come into play.

What you find objectionable is the resonance of the system which also includes the resonance of the drivers. It's not really fixable unfortunately as it's inherent in the whole approach. It's also why this type of design was not popular and eventually faded away.

With all due respect, I am going to take the Jack Plate and Schematic Diagram to a friend, and while I am at work doing my job, have him ReWire the Jack Plate minus the Crossover Circuit Board, and see what this does.

What you all have said is the Crossover is NOT part of the equation, when the 210s and 215s are connected to the Crossover Board, but at least this way we can fully Exclude the Crossover Circuit Board.
.

As has already been stated and repeated ad nauseam, you have already removed the crossover from the circuit by disconnecting the tweeter. The 10s and 15s are not affected by the crossover at all, let alone at the problem frequencies. Rewiring the speakers directly to the jacks is nothing but wasted effort. But, if it will convince you that the crossover is not the issue, then please by all means do it so we can move forward.

 

[NKBassman]

Hey Francis, I don't thing we have gotten past "the crossover must be the cause" phase yet

You couldn't pay some people to take your advice.

 

[Kriegs]

It’s about time for the OP to post a no-crossover test update.

Agreed! Hey, @Nicholas Orick!

 

[Jeff Scott]

There's a reason that free thinking is highly discouraged in the military...

I would NEVER fit in!

 

[thetragichero]

This thread is an instant classic.... or something. :S
Page 12 and still going. I'm super glad I didn't waste my time reading pages 4-11.

yo you missed some witty gems. suggest you go back and read. I've enjoyed myself

 

[Redbrangus]

If it weren't for all the pix--several of which I think may be repeats--it would only be about 6 or 7 pages.

 

[NKBassman]

On top of ignoring good advice, it sounds to me like OP is ultimately going through a lot of effort to try and polish a turd here. Why do you love this cab so much to invest in an additional EQ just to make it usable? You clearly (from pics) already have some other nice options to choose from.

I mean, I understand the desire to troubleshoot and understand and fix a problem (despite OP's seeming unwillingness to accept the collective assessment here), but why must this problem be fixed at all costs? At some point the effort and investment will yield diminishing returns. At the end of the day, it'll still be a turd, just with multiple offending frequency spikes EQ'd out.

I say just dump the Isovent and get literally any other cab you can afford to replace it.