Ampeg Isovent - Jack Plate Circuit Board.

[Jeff Scott]

The schematics and manuals can still be found on the Ampeg website. The crossover is just for the tweeter (5kHz).

This was directed at the OP given his talk of the corssover causing the F-centered wolftone, not really asking if there was a crossover for the "subwoofer drivers in relation to the 10" drivers. I'd have asked it in a different way but that would have been considered violating R#1.

 

[Nicholas Orick]

I have the same cab you are referring to, farace, with the 4U rack built in on top, even if I typed the wrong letters that's what I meant, thanks for correcting me. I was looking for a lll (non-pro) for years and couldn't find one, I am more than happy with the similar mosfet power section of the Walkabout.

So you are using an Ampeg Isovent with a Mesa Walkabout?

Do you get the F Intensity also?

I call it the F Bomb.

I also have a GK RB II and an Ampeg SVP Power & Pre amp, no matter what bass I use, nor which amp I use, I get the F Intensity - F Bomb.

The Ampeg SVP does a better job of dialing out the F Bomb but doing this limits Dialing In possibilities.

.

 

[agedhorse]

I am NOT an Audio Professional, but just a guy learning to play bass at a later date in life, and through this experience I am learning a lot, while at the same time having a lot of fun meeting people like you, who are Audio Professionals, and I tend to agree with you on this point. One shouldn't have to Dial Out UnWanted Sound but instead Dial In What is Wanted.

You are NOT understanding what @Redbrangus said.

Both of us (Redbrangus and me) are pro audio guys in another life, and while it was crystal clear to me what he was saying, it clearly escaped you. Your comment indicates that you are not understanding the whole concept of eq.

One of the primary applications of eq is to remove energy in areas (frequency ranges) that are in excess. Then, if there are areas that are insufficient, eq is then added to increase the energy in those areas.

One caveat though, EQ only works for signal issues in the frequency domain and not in the time domain. If the problem in your case is caused by a significant time offset between the two sections (I do not think this is the case), eq is not going to help much.

 

[agedhorse]

I like the Isovent, I intend on getting it Dialed In the way I wanted it, and I am Keeping It.

No matter what system I get, I always have to learn how to use it, and this always means Dialing It In to the way I want it.

Are you familiar with the concept of a square peg and a round hole? This is something stubborn folks waste entire lives on, not understanding WHY it's not working out. Once you understand WHY, it will be clear that this issue will remain with the cabinet with varying degrees of success.

Out of curiosity, WHY do you like the cabinet?

 

[Nicholas Orick]

This was directed at the OP given his talk of the corssover causing the F-centered wolftone, not really asking if there was a crossover for the "subwoofer drivers in relation to the 10" drivers. I'd have asked it in a different way but that would have been considered violating R#1.

I am going to Remove the Crossover Circuit Board, then ReWire the Isovent, and see what I get.

Hopefully this cures the F Bomb (Wolftone) problem.

 

[Nicholas Orick]

Are you familiar with the concept of a square peg and a round hole? This is something stubborn folks waste entire lives on, not understanding WHY it's not working out. Once you understand WHY, it will be clear that this issue will remain with the cabinet with varying degrees of success.

Out of curiosity, WHY do you like the cabinet?

I like the concept. Two 10s for mid bass with strong and fast bottom end.

Lets see what the square peg in the round hole does.

Or have you ever heard of being Determined against All Odds?

And No I am NOT selling the Isovent, and No I am NOT selling it to you, but one way or another I am going to get the Isovent Dialed In the way I want it. I have Dialed In many pieces of gear and I think I can successfully get this Isovent Dailed In the way I want it. It is just a matter of figuriing out and separating what Needs to be done from what Doesn't Need to be done, and then getting it Done.

Mr Round Peg in a Square Hole.

.

 

[agedhorse]

I would also suggest that the Walkabout is a poor choice of head to use with that cabinet, in fact I really can't think of a worse head specifically because of what makes that head desirable with other cabinets.

The amp damping as very low and the voicing makes this a problem anytime a cabinet has a high Q, especially with high amplitude resonances.

 

[agedhorse]

I am going to Remove the Crossover Circuit Board, then ReWire the Isovent, and see what I get.

Hopefully this cures the F Bomb (Wolftone) problem.

It's not going to make a bit of a difference. Again, stubborn is the man who slams his had in a door again and again expecting different results yet not caring to learn why it hurts every time.

I like the concept. Two 10s for mid bass with strong and fast bottom end.

Lets see what the square peg in the round hole does.

Or have you ever heard of being Determined against All Odds?

.

Ok, you like the concept even though you don't understand then concept? The 10's are no faster than the 15's, and the 15's do not make for fast bottom end either.

Are you aware that the speed of sound is the same for all frequencies (within reason)?

Yes, I am aware of determined against all odds, it's also called reckless gambling.

 

[Nicholas Orick]

You are NOT understanding what @Redbrangus said.

I hear you both.

First let me Remove the Crossover CircuitBoard and see what that does.

Eliminate Extraneous Problems first then see what this leads to.

Both of us (Redbrangus and me) are pro audio guys in another life, and while it was crystal clear to me what he was saying, it clearly escaped you. Your comment indicates that you are not understanding the whole concept of eq.

One of the primary applications of eq is to remove energy in areas (frequency ranges) that are in excess. Then, if there are areas that are insufficient, eq is then added to increase the energy in those areas.

One caveat though, EQ only works for signal issues in the frequency domain and not in the time domain. If the problem in your case is caused by a significant time offset between the two sections (I do not think this is the case), eq is not going to help much.

 

[frankie5string]

I suppose it's an ok hobby to keep someone otherwise out of trouble to futz with this. But I still think that cabinet sounded gross in the few times I've been able to play through one.

 

[Nicholas Orick]

It's not going to make a bit of a difference. Again, stubborn is the man who slams his had in a door again and again expecting different results yet not caring to learn why it hurts every time.



Ok, you like the concept even though you don't understand then concept? The 10's are no faster than the 15's, and the 15's do not make for fast bottom end either.

Are you aware that the speed of sound is the same for all frequencies (within reason)?

Yes, I am aware of determined against all odds, it's also called reckless gambling.

Are you aware the Isobraic loading makes for Faster Subs. It isn't just Power it is also Speed.

I am Aware of More than you Realize.

Especially with you guys really tossing it at me.

You guys have been Very Informative.

Lets see what Removing the Crossover Circuit Board does.

Then we can argue about Frquencies and Time Domains.

.

 

[Wasnex]

In the late Seventies/Early Eighties there were a plethora of similar designs put out by small speaker cabinet manufacturers around here. One was Power Supply. Over the years that followed less and less of these sometimes bizarre topologies were to be seen. Many of them looked great on paper but not so good in real life.

I feel that the OP should put his cabinet back together properly and sell it. It might well go to someone who loves the box despite the designs flaws.

I remember listening to some Linn isobarik speakers back in the day at one of my favorite HiFi stores and they sounded fabulous. The only flaw as far as I am concerned is they were way out of my price range and supposedly required a stout power amp.

 

[Wasnex]

I am going to Remove the Crossover Circuit Board, then ReWire the Isovent, and see what I get.

Hopefully this cures the F Bomb (Wolftone) problem.

Just turn the tweeter off the crossover is effectively removed from the circuit.

 

[Nicholas Orick]

It's not going to make a bit of a difference. Again, stubborn is the man who slams his had in a door again and again expecting different results yet not caring to learn why it hurts every time.



Ok, you like the concept even though you don't understand then concept? The 10's are no faster than the 15's, and the 15's do not make for fast bottom end either.

Are you aware that the speed of sound is the same for all frequencies (within reason)?

Yes, I am aware of determined against all odds, it's also called reckless gambling.

Also the differences in Masses leads to a difference in Sound Speeds.

The larger heavier Mass Speakers will tend to be Slower unless Compelled by a more Substantial and Faster Force.

Also the larger diameter cones will meet greater Air Resistence which will effect performance values.

So again there is a difference between the 210s and the Isobraic Loading of the 215s.

And these Other Factors will effect the Frequencies over the Time Domain.

With Humor I say - Dummy.

.

 

[Nicholas Orick]

Just turn the tweeter off the crossover is effectively removed from the circuit.

Everything is Connected to the Crossover.

The Conjoining Point is the Source of the F Bomb.

.

 

[Redbrangus]

Wow...you really are determined. I wish you the best of luck. And offer my apologies for whatever guff I tossed your way.

I seem to remember Krusty the Clown laying a bet on the Washington Generals over the Harlem Globetrotters because "they were due".

 

[BassmanPaul]

I remember listening to some Linn isobarik speakers back in the day at one of my favorite HiFi stores and they sounded fabulous. The only flaw as far as I am concerned is they were way out of my price range and supposedly required a stout power amp.

When I first arrived in Canada I took a job at a High End HiFi store to get me through the winter. They has some beautiful stuff that was out of my price range. Before I left a few months later I had bought some nice used stuff. My practice set up revolves around a Nakamichi preamp with my computer in a Tape Loop. On top is a Sansui tuner for music while I'm changing stuff around.

 

[Jeff Scott]

The Conjoining Point is the Source of the F Bomb.

Good song title!

 

[JeezyMcNuggles]

I like this Isovent.

I think I am going to fix it up to do what I want it to do.

It is just a matter of tracking the problem down to the cause and fixing it.

It's most likely a resonant frequency problem. The cabinet is bringing out the F. Just like D shakes my house at any level or octave. Same with the cabinet. Your hitting the sweet note of the cab. Most have one. Think of it as you are hitting that note twice. Once on your bass and once on your cab at the same time. Just hit that note softer, or staccato. You could also try elevating the cabinet. That could help in making it less noticeable.

 

[frankie5string]

Wow...you really are determined. I wish you the best of luck. And offer my apologies for whatever guff I tossed your way.

I seem to remember Krusty the Clown laying a bet on the Washington Generals over the Harlem Globetrotters because "they were due".

"Kruddler"...

Everything is Connected to the Crossover.

The Conjoining Point is the Source of the F Bomb.

.

That's because the crossover board doubles as a terminal hook-up for all of the speakers. I suspect the two 15s are just wired to parallel tracks on the board - no components or inductors... although it might also go through the light-bulb limiter. I don't think those 15s are even really true sub-drivers... I think they're just bass-guitar range 15s designed to work in that application.