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Discussion Starter #601
AWESOME thread! Nice to see another Boston Acoustic GT amp out there!
Thanks for the nice comment. I love Boston Acoustics. Their products were ahead of their time, especially with the Pro Series Speakers. They came with matched set of tweeters.

Who does that today? No Car audio company that I know of. And I have not heard a modern car audio speaker that sounds as good as the Boston Acoustics Pro series.

I'm not very sure how the Amplifier's stack up, but I know some of the GT amps were made in Italy in the Steg ( Mosconi ) factory and some were made in Malaysia.
 

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Discussion Starter #603
I hung a ping pong ball from the ceiling with a string. Dead center of the cab, centered of the listening seat, right in front of my nose. The photo I took was really quick and the ball was swinging and the camera wasn't centered so it looks a hair off in the photo, but it's just parallax.

This time, instead of aiming for a point behind my head using a framing square and string, I decided to use a laser level.

I made the drivers all aim directly at the string of that the ball was hanging from. The laser level lit up the entire length of the string.

Enclosures were not only located the same distance from the string but symmetrical in the cab as well.

This one change made for the most dramatic improvement that I have ever done. The install is very, very important when it comes to getting imaging and transparency, and cohesiveness, as many of ya'll have tried to hammer in my head over and over.

Of course I had to redo time alignment as all distances changed. I used Erin H's Tracerite.calc software to get me in the ball bark. The final delay settings were not very far off. Having only 6 drivers, and a center seat makes for only two delay figures.

LISTENING IMPRESSIONS:

I've been listening with the doors open, because I'm setting the system up for my enjoyment and not for competing.

Hollow sounding character went away. Having the drivers aimed to a spot in front of my nose ( tip from Nick Apicella tuning video ) as opposed to a spot just behind my head made the hollow sound go away that no amount of tuning could fix.

DEPTH: The depth increased dramatically. This was one area I could not improve prior, no matter what I did with the DSP settings.

Cohesiveness: All the drivers are now working in unison to create a unified sound. This caused the realism to increase along with transparency.

RTA: The peaks were easier to locate and hear. I used a phone app RTA and made a few tweaks to my EQ settings got a relatively flat and smooth waterfall response curve for the very first time. I was shocked on how much easier it got to tune now that the speakers are all more accurately aimed to a better spot in front of the listening position.

The green peak lines in the RTA photos were before and after re-aiming of drivers with a handful small EQ tweaks. There was a dramatic increase in the smoothness of the response curve. This before/after ( re-aiming of drivers ) RTA measurements really shocked me.

I still have some minor fine tuning EQ tweaks to do that are not far off from the major EQ work I did a few weeks ago. Even the problem areas I had around 100-125 Hz went away just by lowering 25 and 50Hz a tad.
These same adjustments did not help earlier when I tried them.

I learned that sometimes RTA issues that show up on the graph do so at a harmonic frequency and cannot be fixed by tweaking that harmonic frequency.

The way the system sounds now, compared to any point in the past, it seems like the I had been competing with an un-tuned system. I'm surprised that I managed to do as well as I did.

I had ordered a bunch of old school analog equipment that I was going to try and incorporate into the system, but at this time I am truly happy with the way the system sounds.

I also ordered the matching Processor that goes with the Sony head unit to try as an experiment as well. It has four 24 bit D/A converters instead of the dual 20 bit D/A converters which in theory should give for even more precision.

Other than the fine tuning EQ tweaks that I have to do, I can't imagine the sound improving much from where it is at this point.

I have learned a hard lesson about the importance of tuning and install. In the past, I was very hard headed and close minded.
 

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Discussion Starter #604 (Edited)
I'm very much happy with the sound of the system. I've never been satisfied, or content in the past and always felt the system needed a professional tune because I wasn't able to get it quite right.

But now, with the speaker relocation/re-aiming the tuning process is getting easier. I have to admit that having such large drivers that are made to fill up a room in a house make for a challenge when put into a relatively small space such as the passenger compartment of a step van.

With a tip from a facebook group post, I learned that individual EQ of every pair of drivers and sub was necessary in order to get clean, focused, detailed, sound with the correct tonality.

Last night I turned my AE 18" sub back on and now that the rest of the system is tuned properly, the sub added to the overall SQ of the system rather than detracting. I messed around with crossover point and it seemed to be most cohesive with the rest of the drivers when crossed at 50hz 4th order LR.

But I had to individually EQ all 31 bands on the Sub itself in order to get clarity and focus.

So now that I'm totally happy and satisfied with the sound after a long 7 1/2 year process of designing and fabricating and installing and learning how to tune, I've reached a point where I'm very much content and have something that I'm proud of.

I really do not wish to touch the system as it stands, but I'm going to continue to do a couple more experiments.

The first is to install the matching Sony ES processor that is designed to be used with the Sony ES Head unit. The head unit has dual 20 bit DA converters and the processor has quad 24 bit. I'm going to be just passing the digital signal from the Sony CDX-C90 source unit via optical cable to the XDP-4000X and using it only for the DA converters which will output full range signal via a set of RCA cables to the ARC PS8 which will still handle all of the processing.

The second experiment will be to install and re-tune using all the analog gear in the photo below. I'll be using the settings I made in the PS8 and transferring those to the analog counterparts.

The Nakamichi will be used to cross the signal, the Audio Control EQT's will handle each set of Driver individual EQ, and I found some Precision Power phase shift controllers to dial in the time alignment.

At this point in time, I have no idea what I am in search for because I really don't want to change the way it sounds, however, I purchased this gear before I made the driver re-aiming and alignment so I'm committed to at least try the stuff out to satisfy my curiosity to see how going back to all analog compares.
 

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Good stuff Gerald! I’m really interested in your evaluation of each experiment.

The Sony piece before the PS8 - whether you can discern an improvement vs going from the HU directly to the PS8.

And I’m very intrigued whether putting the same settings into the analog pieces that are in the digital piece will render a similar sound or a radically different sound. Pretty cool to see all the analog pieces that are needed to do the ‘same’ thing that the one digital processor can do.

I’m glad you are willing to do all of this so we can get your impressions from these experiments - you will need to bring it down to NC so I can here the changes too!


Sent from my iPhone using Tapatalk Pro
 

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Discussion Starter #607
Good stuff Gerald! I’m really interested in your evaluation of each experiment.

The Sony piece before the PS8 - whether you can discern an improvement vs going from the HU directly to the PS8.

And I’m very intrigued whether putting the same settings into the analog pieces that are in the digital piece will render a similar sound or a radically different sound. Pretty cool to see all the analog pieces that are needed to do the ‘same’ thing that the one digital processor can do.

I’m glad you are willing to do all of this so we can get your impressions from these experiments - you will need to bring it down to NC so I can here the changes too!


Sent from my iPhone using Tapatalk Pro
I've been re-listening to all your disks in the last few days. Some amazing sounding tracks in the mix for sure. I was just thinking to myself that out of everyone I know, I feel as if you would enjoy listening to music the most on this system.

So it is my goal to get you in the center seat, so a trip to NC may be in the future!!!
 

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Discussion Starter #608 (Edited)
Good stuff Gerald, can’t wait to heat it at your next get together
I may try an throw a last minute GTG Sunday November 10th in Taunton, MA which is closer to you by about 1/2 hour from the last GTG, but I'm waiting to hear back from the host to see if it is ok with him.
 

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I may try an throw a last minute GTG next Sunday in Taunton, MA which is closer to you by about 1/2 hour from the last GTG, but I'm waiting to hear back from the host to see if it is ok with him.
If my son doesn’t have a playoff game too late I’ll make an appearance Gerald for the GTG. That’s only an hour and 7 minutes from me.

Also, as soon as you know for sure I can put it up on other places as well.
 

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Discussion Starter #610

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Discussion Starter #611
I've been tuning by ear for a very long time.

Every time I think that it sounds the best it ever has, I leave and come back, listen to the system again and I hear things I don't like.

So I decided to tune with a microphone, REW, and some pink noise. It took me just about 3 hours.

The sound is different for sure. It's probably a good competition tune as music sounds as it is pushed far away from the listening position.

I guess this is the correct way to listen to music, but I'm not use to it. My normal is where the listening position is in the middle of the orchestra, or in the middle of the audience.

Having all the frequencies play at or near the same volume level sounds very smooth, but I feel like all the life or "as if you were there" quality has been removed.

For example, there is a track where I was once in the audience listening to a guitar play. People were randomly hooting and hollering and I remember being startled when they yelled out as if someone was sitting right next to me and it shocked me as it sounded like a real person just randomly yelled out and it felt like they were in the van with me.

That same track now sounds as if I'm positioned well back from the audience and that same hollering isn't as startling. Don't get me wrong, it still sounds like a real person, however, I'm seated further away from that person.

The sound on the far Right and Left edges of the stage use to wrap back almost to my immediate flanks and made for a headphone like type of experience.

With this tune, the Far Left/Right stage boundaries are pushed further away towards the windscreen.

I know when I first started learning how to tune, and heard all the instruments separated from one another, I didn't like it in the beginning. It took me a year 1/2 to two years to get use to listening to music that way.

Today, listening to music in my personal vehicle without separation drives me crazy.

Perhaps, I will get use to listening to music this way, only time will tell.
 

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Discussion Starter #612
I also noticed something interesting.

When my system was tuned by ear (or in essence not smooth response curve) small .01 DB adjustments made a noticeable change in the sound.

After using REW and a Microphone and getting the adjoining frequencies close to the same level, I figured that I would have to fine tune by ear each and every frequency for all 31 bands of every driver to dial it in as I had done many on past tunes.

What surprised me is that making those small adjustments up or down in .01DB increments did not seem to have an audible effect?????

This might make sense to those that are more experienced than me, but I found it interesting.

The tune with the Response curve in the photo below has the top end slightly inclined. The next day this tune sounded slightly fatiguing, so I made the top end flat, which fixed that issue.

Later today, I will take another listen and see if I'm happy with the tune as it stands.
 

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Looks like your subwoofer is out of phase with your mids from that REW graph. Time alignment should be checked for that to make sure its correct or this can happen. Not knowing what DSP you have can you switch back and forth between tunes to compare them. This sometimes helps me figure out what I like best. I will often switch back and forth while listening to songs on my long drive to Boston to compare them. I learned a lot in the beginning on figuring out my personal preferences.
 

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Discussion Starter #614 (Edited)
Looks like your subwoofer is out of phase with your mids from that REW graph. Time alignment should be checked for that to make sure its correct or this can happen. Not knowing what DSP you have can you switch back and forth between tunes to compare them. This sometimes helps me figure out what I like best. I will often switch back and forth while listening to songs on my long drive to Boston to compare them. I learned a lot in the beginning on figuring out my personal preferences.
It took me a while to figure out how to figure out why I wasn't getting much sound from my woofers. I played test tones and from 50 hz to 80 hz there was nothing.

I started testing everything and finally I checked my one parametric EQ setting.

It was at 316 HZ so I didn't think it would have an effect on the sound, however I was trying to have a huge narrow cut at that frequency. -12.4 gain.

I got mixed up with Q. I had put a Q setting of .1 when I should have had it at 19.9

So I had a huge swath of frequencies that were cut out.

I was wondering why I had such a huge suck-out. LOL!

Thanks for pointing that out to me!!!!

That problem is fixed however now I have to do a complete re-tune.
 

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Discussion Starter #615
With some technical help from a couple of friends ( as I'm not computer literate enough ) Installed the Sony XDP-4000 Processor last night. I thought I had all the necessary equipment but I had one wire too short.

I needed an optical converter for the back of the head unit, Optical cable, USB to serial Bus Adapter with driver software, Null cable, Windows XP laptop, and Uni-link cable to go between the head unit in the front and processor in the rear.

The Processor only came with a 6 foot Unity cable so I had to improvise in order to test the sound. Removed the air conditioner in order to pass the cable into the cab through one of the AC holes. Also had to remove the head unit form the enclosure in order to make things just reach as the power wires come from the front. I had to cut the head unit enclosure so that the 90 Degree optical adapter and cable would plug in and seat flush.

I found a 19 foot cable on E-bay and ordered it last night, so it should be arriving in the next few days.


Listening impressions:

The digital to analog converters in the Processor make for a clearer, cleaner, crisper sound. I noticed the attack is quicker, and the micro details have gotten better. There is a bit more realism, as it sounds more like the listener is in the room with the musicians.

The characteristic that would describe the change that occurred by adding this piece into the loop was more Precision.

As a side benefit, by pulling the AC away from the wall and exposing the small passageways through the wall into the rear compartment of the van, the overall sound changed for the better in my opinion.

Allowing the air pressure created in the Cab to be able to escape to the rear compartment through those small vents allows the system to "breathe" better for lack of better terms. I kept listening to music and switching back and forth between plugging the vents with the AC and moving the AC back away from the vents.

Having the vents open makes for a more natural, open and airy sound and it affects all frequencies. This was an interesting and surprising side benefit, that I was not expecting. I guess Ben Zimmerman's comment about having more air space has come into play in this scenario.
 

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Discussion Starter #616 (Edited)
The used 19' cable came and i hooked it up last night. It must have a short in it as my CD Drive would not play, the display would not light up, and the drive made weird noises, after installation.

So when pulling the head unit back out to disconnect the defective cable, I broke the all important/delicate Sony Optical cable adapter, which only comes in a 90 degree angle causing my demise.

I ordered a new Optical Adapter and set of New AI Net Cables which will be here in a few days.

So for the get together on Sunday, I'll just be running off the head unit D/A's, not the Sony Processor 24 Bit D/A's.

But the 20 Bit Sony C-90 happens to be more precise than all the 1 Bit Alpine units that I have run in all competitions since starting competing.

It's a serious piece in itself.
 

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Gerald, I see that you have the Sony RM-X9 wireless IR "candy bar" remote for CDX-C90. Do you also have the RM-X90 wired rotary commander remote?

Also, if your main source for music playback is still via CD discs, you may want to add one or two Sony 10-Disc CD Changers to your C90/XDP-4000X setup.

You can usually find the Sony 10-Disc CD Changers fairly cheap on eBay. Make sure the model that you purchase has the Toslink Optical Digital Output and includes the 2 mounting feet.

The Toslink digital output from the CD Changer plugs directly into the XDP-4000x processor, and you would need another Sony Uni-Link bus cable to connect the two as well.

The Sony CDX-828 was a popular 10-disc CD changer that has the Toslink optical output, and there are a lot of them out there. It was actually one of Sony's "ES" units even though that designation isn't in the actual model number. See this eBay auction for reference...

https://www.ebay.com/itm/Sony-CDX-C90-Sony-CDX-828-RARE-NEW/312534149071

There are a few other Sony CD changer models with the Toslink output as well, but the 828 was most popular.

And the interchangeable/swap-able #XA-10B 10-disc CD magazine/cartridges are plentiful on eBay as well.

The SQ when adding the XDP-4000X to the C90 is definitely a step up, and IMO still holds its own in comparison to more modern "DACs" in current DSPs.

Have fun with it.
 

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Discussion Starter #618
Gerald, I see that you have the Sony RM-X9 wireless IR "candy bar" remote for CDX-C90. Do you also have the RM-X90 wired rotary commander remote?

Also, if your main source for music playback is still via CD discs, you may want to add one or two Sony 10-Disc CD Changers to your C90/XDP-4000X setup.

You can usually find the Sony 10-Disc CD Changers fairly cheap on eBay. Make sure the model that you purchase has the Toslink Optical Digital Output and includes the 2 mounting feet.

The Toslink digital output from the CD Changer plugs directly into the XDP-4000x processor, and you would need another Sony Uni-Link bus cable to connect the two as well.

The Sony CDX-828 was a popular 10-disc CD changer that has the Toslink optical output, and there are a lot of them out there. It was actually one of Sony's "ES" units even though that designation isn't in the actual model number. See this eBay auction for reference...

https://www.ebay.com/itm/Sony-CDX-C90-Sony-CDX-828-RARE-NEW/312534149071

There are a few other Sony CD changer models with the Toslink output as well, but the 828 was most popular.

And the interchangeable/swap-able #XA-10B 10-disc CD magazine/cartridges are plentiful on eBay as well.

The SQ when adding the XDP-4000X to the C90 is definitely a step up, and IMO still holds its own in comparison to more modern "DACs" in current DSPs.

Have fun with it.
Thanks for the comment, I see that I have a lot of followers but not many people actually post.

I actually purchased the C-90 Brand new in box last year, so I do have the RM-X90 wired remote, as well as the candy bar IR Remote.
I'm using just the IR remote during listening sessions.
As far as getting a CD changer, I've used them back in the day ( pioneer 6 disk ).

95% of the time, the van really just sits in my heated workshop and I use it to decompress after work to listen to music in before heading home in my personal vehicle .
The front windows are blacked out and there is egg crate foam along the side windows to help tame reflections.
The other 5% of the time, I'm traveling with it to competitions or our semi-annual SQ Get together events.

I like that idea of a changer or two as I could put many disks ( Jason Bertholomy's Disks ) in and not have to shuffle through disk after disk.
But at the same time, I was just thinking that maybe a simpler step up might be easier and possibly a step better.

I was thinking re-installing/using my Oppo Universal Disk player which can play Blu-Ray audio at a higher bit and sampling rate and sending the signal from that via RCA or maybe even better, Digital optical or digital coaxial directly to the ARC Audio PS8 which handles all the processing now.

I am using the Sony XDP-4000X just for the D/A converters.

The Oppo Blu Ray player has dual 32 bit D/A converters, one for stereo and one for 7.1 channels. The SABRE32 Reference ES9018 from ESS Technology. Here is a link to the specifications for that chip:
They market it as the world's highest performing D/A converter solutions.



ESS Technology :: SABRE DACs



It might sound like I keep changing gear on my system because I'm not happy with the sound.
Don't get me wrong, I'm very happy and content with the sound, but when it comes to this system, I love experimenting and pushing the boundaries when it comes to gear. My goal is to squeeze every last bit of sound quality that I can out of this system.

I have taken this system past my wildest expectations and every time I experiment with a new piece, I get shocked with the results. I'm sure at one point I'll reach that point of diminishing returns, but for now the experiment continues.
 

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Discussion Starter #619
I just experimented with a tuning method that made a significant improvement with a dramatic jump in realism, detail, and separation.

For years, I was convinced that I could tune by ear and recently discovered that a microphone and pink noise yielded better results.

Just a few nights ago, I took my microphone REW tune and listened to test tones on an old school IASCA CD that someone had sent me as a gift when purchasing one of my Old School Phase Shift units. This was the same tune that took me 3 hours with REW and the UMIC 1 and Pink Noise.

I noticed that when playing test tones that there were significant variances in volume levels both audibly and with the use of a phone RTA app. of many different frequencies between 20hz and 20Khz.

The differences surprised me as I though that Pink Noise was a close representation of all frequencies at the same volume level. But for some reason, it was way off. It reminds me of when I watched Kyle Ragsdale tuning video series on Youtube and he noticed the same thing.

So I made very significant cuts ( both with Parametric and Graphic and even used some global EQ ) and it took about an hour. This was done just using the phone RTA App. ( I-phone 7 in battery case )

All I can say is WOW!

Everyone should be tuning with 30 band test tones instead of Pink Noise
( unless one can find corrected Pink Noise ). The Pink Noise I had used in the past was from Sheffield Labs - MY Disk as well as the Pink Noise from the same Old School IASCA test CD.

Besides the improvements that I listed above, what shocks me even more is that the system jumped up leaps in how revealing has become.

I've been using Jason's Bertholomy's GTG disks as my reference material, as the music he chose is well recorded, is from many different Genres and interesting track selections.

However, with this new tuning method, I found not only dramatic improvements in details in the music itself, but it seems like now the differences in recording methods that the recording engineer chose ( such as microphone quality choices, cable choices, microphone location distances from instruments and singers, mixer equipment selection, etc. ) vary significantly from track to track. Not to mention getting a much higher sense of the characteristics of the room in which the recording was made.

It also reveals more so, the response curve that the recording engineer chose to Master the recording with. It seems as if when the levels are set evenly on one's system, more details become unmasked.

Now I'm curious to see if I used the same test tones and REW with the Umik 1 and spend several hours getting the curve even smoother, if there will be another change?
 

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Glad to see you’re making strides towards nailing down a tuning process Gerald. I just redid the tune for my Sienna last night and I’m shocked at how much better it sounds now. I followed the same process I used on my CX5 which I’ve perfected over the last year on my Ford.

I wonder how Jim is making out with what he learned at the meet. I haven’t heard from him. I was going to suggest that he disable his midrange in his DSP and tune the system as a two way active. If he still has the same issue than it’s not his midrange that is the problem.
 
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