Ampeg Isovent - Jack Plate Circuit Board.

[Nicholas Orick]

I'm starting to feel bad. I'm not intentionally trying to be mean or pick on the OP here, but this exchange is rather damning.

Why do you guys keep calling me OP?

What does OP mean?

 

[Nicholas Orick]

If the 15s, out side of the cabinet, with the 210s disengaged, still resonates, then the 15s are the “problem”. The jack plate circuit board is not the same thing as a crossover. The crossover is just a single component on the circuit board. If you disengage the tweeter you bypass the crossover.

The 210s also resonate the F Bomb independent of the 215s.

One way or another the F Bomb is present. This means a common source.

 

[agedhorse]

Another idea.

Take an Array Module and use that.

This is in response to a question regarding using something "more modern".

Except that the high frequency section of the line array modules is very, very narrow (by design) in the vertical plane (with the normal orientation). It's totally the wrong product for the application, though it is more modern. I wouldn't expect it to work any better than then hot mess you already have... but for different reasons.

Why do you guys keep calling me OP?

What does OP mean?

Original Poster

 

[Nicholas Orick]

Except that the high frequency section of the line array modules is very, very narrow (by design) in the vertical plane (with the normal orientation). It's totally the wrong product for the application, though it is more modern. I wouldn't expect it to work any better than then hot mess you already have... but for different reasons.



Original Poster

 

[Nicholas Orick]

This looks like a really cool bass cab to take to a gig.

A "more modern" approach.

.

 

[agedhorse]

If you listen with your eyes perhaps. I think you will find the low frequency response to be underwhelming, every one of these products are designed to be used with subs when reproducing signal with extended low frequency response.

Before you tell me that I don't know what I'm, talking about (again), that's the industry I worked in, toured in and designed for starting in 1980. There are some (higher end) commercial line array products have my engineering work in them.

I also have a whole warehouse full of them and worked with them several times a week.

 

[Nicholas Orick]

If you listen with your eyes perhaps. I think you will find the low frequency response to be underwhelming, every one of these products are designed to be used with subs when reproducing signal with extended low frequency response.

Before you tell me that I don't know what I'm, talking about (again), that's the industry I worked in, toured in and designed for starting in 1980. There are some (higher end) commercial line array products have my engineering work in them.

I also have a whole warehouse full of them and worked with them several times a week.

A). I Never said you didn't know what you are talking about.

B). I like the idea of somehow purchasing a Line Array Module and using that for a Bass Cab for playing smaller gigs. This idea kind of makes sense. Take a splice off the whole and use that for small gigs. Kind of a newer "more modern" approach.

How can I contact you more directly?

Also, can I plug a Pre/DI directly into one of these line array modules or do I need a mixer in between?

 

[Redbrangus]

I was thinking that the JBL VT-4888 shown would be a singularly bad bass cab. Not as bad as the Iso-vent, but then, it isn't marketed as one. I never send anything to those boxes lower than 80Hz, although JBL does refer to them as 'full range'. BTW, that cab, used vertically, as shown in the pic, would have about a 10-degree horizontal dispersion...I'm not sure why one would consider that advantageous.

 

[PraiseBassing]

My hunch is, the Isovent was originally designed to bring out the four string bass beginning with the Open E, but I usually play five and six string basses with the Open Low B, and the Cross Over Circuit was designed with the four string Open E basses in mind. As a result there is something Ampeg probably did with the design of their Cross Over circuit towards bringing out the Fs of the four string basses.

I am not sure if this has been mentioned or not yet, but the problem with this hunch is that the Isovent was Ampeg’s early attempt at creating a cab that reproduced low frequencies “produced” by extended range basses. It was not created to emphasize an open E. Most of the early cabs that were attempts at going low had very obnoxious peaks in their frequency response, like your “F bomb”

 

[agedhorse]

B). I like the idea of somehow purchasing a Line Array Module and using that for a Bass Cab for playing smaller gigs. This idea kind of makes sense. Take a splice off the whole and use that for small gigs. Kind of a newer "more modern" approach.

Also, can I plug a Pre/DI directly into one of these line array modules or do I need a mixer in between?

How in the world does it make sense? The low frequency response is optimized for 80hz and above on most of those, and what would be your horizontal high frequency pattern would be only 10 degrees high (and rip your head off on axis with virtually nothing off axis).

The powered and processed line array modules generally can accept line level balanced signals of at least +4dBu (absolute minimum). Some preamps can deliver this (all of the ones I designed will) but it should be understood that many will not.

 

[DJ Bebop]

View attachment 3679682 This looks like a really cool bass cab to take to a gig.

A "more modern" approach.

.

Nope, I wouldn't gig it as a bass cab
Unless I had something like this to go with it:

 

[DJ Bebop]

When you 'test' the speakers outside the cabinet, are they still connected to the other speakers via the crossover you are not testing? And if so, are the other speakers still in the cabinet producing sound?
At the same time?
Ampeg Isovent - Jack Plate Circuit Board.

I tried

 

[Nicholas Orick]

Well in the mean time

I am not sure if this has been mentioned or not yet, but the problem with this hunch is that the Isovent was Ampeg’s early attempt at creating a cab that reproduced low frequencies “produced” by extended range basses. It was not created to emphasize an open E. Most of the early cabs that were attempts at going low had very obnoxious peaks in their frequency response, like your “F bomb”

Even though most seem to think the Crossover terminal block is NOT the cause of the F Bomb, I think it is, and I have pulled out the Crossover, capped off the tweeter (which I never use anyway), and a friend is rewiring the Isovent.

From there we will see what we get.

If the F Bomb is removed then great, if NOT then we will figure out what to do next, and if Nothing Else, this is turning out to be a fun little project to pursue.

I am hoping the removal of the Crossover removes the F Bomb, and with the way my friend and I have decided to rewire it, if it works, then this particular Isovent should work out to be a fun bass cab to use.

Actually the more I learn about this Isovent the more I am beginning to like it. It is sort of a strange concept that maybe went under appreciated.

We will know soon enough.

Also you are correct, in learning about the history going into the Isovent, Ampeg was actually trying to out do their 8x10 while going lower in a smaller cab.

So what you say is True.

Now let's see if my friend and I can make it work more properly.

Again - we'll.

.

 

[DJ Bebop]

Well in the mean time


Even though most seem to think the Crossover terminal block is NOT the cause of the F Bomb, I think it is, and I have pulled out the Crossover, capped off the tweeter (which I never use anyway), and a friend is rewiring the Isovent.

From there we will see what we get.

If the F Bomb is removed then great, if NOT then we will figure out what to do next, and if Nothing Else, this is turning out to be a fun little project to pursue.

I am hoping the removal of the Crossover removes the F Bomb, and with the way my friend and I have decided to rewire it, if it works, then this particular Isovent should work out to be a fun bass cab to use.

Actually the more I learn about this Isovent the more I am beginning to like it. It is sort of a strange concept that maybe went under appreciated.

We will know soon enough.

.

Again I ask.
When you 'test' the speakers outside the cabinet, are they still connected to the other speakers via the crossover you are not testing? And if so, are the other speakers still in the cabinet producing sound?
At the same time?

 

[Nicholas Orick]

When you 'test' the speakers outside the cabinet, are they still connected to the other speakers via the crossover you are not testing? And if so, are the other speakers still in the cabinet producing sound?
At the same time?

I tested all the speakers in various ways, both in and out, and always the F Bomb is present.

This meant a common point was causing the F Bomb.

 

[DJ Bebop]

I tested all the speakers in various ways, both in and out, and always the F Bomb is present.

This meant a common point was causing the F Bomb.

All of them out at the same time? Like the 10s and 15s laying on the floor together not coupled to the cab?

 

[Nicholas Orick]

All of them out at the same time? Like the 10s and 15s laying on the floor together not coupled to the cab?

I did it separately. 210s and 215s separately.

It is the Crossover Terminal Block.

By the way, my friend worked on speakers for traveling road shows and knows what he is doing.

.

 

[DJ Bebop]

I did it separately. 210s and 215s separately.

It is the Crossover Terminal Block.

By the way, my friend worked on speakers for traveling road shows and knows what he is doing.

.

So, like the 10s were still in the cab while the 15s were out and then you tried the 10s out with the 15s in? One set of speakers always coupled to the cabinet?

 

[Nicholas Orick]

So, like the 10s were still in the cab while the 15s were out and then you tried the 10s out with the 15s in?

Yes

 

[DJ Bebop]

Yes

So, one set of speakers was always coupled to the cabinet also making a sound?

If so the cabinet may be adding a resonate peak. Bad glue joint or panel resonates. The cabinet itself is also a common point as well in that scenario.

I would try decoupling all the speaker from the cabinet at the same time and see what happens