DSP- one person's experience

[JackD201]

Ken I am one of the members who doesn't use TacT. I have talked with Marty about it. He tells me not to. Last week Amir spent a few hours with me. I had a long discussion with him about integrating my Gotham subs as well as DRC. Amir felt I would notice improvements BUT at the expense of sacrificing much of the magic that the Lamm produces in the midrange and highs
Suffice it to say I am not prepared to do this. I would love to get a 2.2 into my system to A/B. Amir on his next trip down can hopefully bring his

Inserted between the Playback Designs player and the LL1, the LL1 and ML3 interface should be unharmed.

How many inputs and how many custom curves can be assigned/saved on the 2.2?

 

[RUR]

How many inputs and how many custom curves can be assigned/saved on the 2.2?

The 2.2XP (curent model) has five digital and, assuming one has the optional A/D card, four analog inputs. It holds nine correction presets + Bypass.

 

[marty]

RUR,
I do not have the B&K curve in the TacT file format. But remember, the B&K curve is not the target curve you would necessarily enter to get the desired result. Rather, the B&K curve is the result of a target curve that you would enter, so you would produce a system response which is the B&K curve at the listening postion. The actual target curve I use is significantly different from the B&K curve due to some vagaries of the TacT that I'm not sure I fully understand. I also suspect that due to differences in gear, room acoustics, percent of direct and reflected sound among users and their systems, there would be a certain range of variance among target curves that could be entered into the TacT to wind up with an accurate replica of B&K curve as the net output at the listening position in any given system. The beauty of the TacT 2.2XP is that changes can be made quickly in real time and the results validated independently with pink noise and a separate spectrum analyzer such as the modestly-priced Phonic PAA3 hand-held personal audio assistant (http://www.phonic.com/en/paa3.html).

 

[Mobiusman]

DSP Can Put A Smile On Your Face

Marty,

Not only have you stated your positions eloquently, but without the slightest bit of smoke, mirrors and/or BS that are killing what should be a hobby dedicated to the love of music and immersive experiences. One of the few benefits of being an aging audiophile is that I was around years ago when there were a lot of great audiophiles who decided to open stores to share what they loved and hopefully make a few bucks to cover their own purchases. Put simply, it was a ball to go to their stores and explore. They were eager to share what they knew about audio and certainly wanted to explain their latest discovery.

Today, it is virtually impossible to find an audio store where the proprietor hails from this planet, has the equipment you want to hear in their store, has a clue how to set up a good sounding system and has anything to talk about other than the demise of the good ole days when honesty prevailed; you could take the time to actually listen before making a purchase; and enthusiasts could actually contemplate being able to afford the equipment they enjoyed. As the price of admission to high end audio soars exponentially, well beyond the budgets of even the privileged, and JV-esque pundits tout the latest and greatest, while breeding discontent with more worldly and frequently superb products, we need more people like you speaking the truth with nothing personal to gain except to help those who understand that the best system is the one that make you sit down and smile.

I have been fortunate to have smiled many times over the years listening to your system and have no doubt that what you are saying about DSP is true. I have also shared many listening experiences with you in various "audio mecca's", where, instead of smiling, we were trying to think of the polite way to exit "stage left" because we were not having fun and certainly did not have smiles on our faces.

I hope that your benevolence will extend to a DSP Part 2 where you describe the "pearls of wisdom" you have learned from 100's of hours experimenting with DSP to put the audio smile back on the face of people listening to your system because what they heard was not the system but the music. Thanks for being a mench.

russ

 

[RUR]

But remember, the B&K curve is not the target curve you would necessarily enter to get the desired result. Rather, the B&K curve is the result of a target curve that you would enter, so you would produce a system response which is the B&K curve at the listening postion. The actual target curve I use is significantly different from the B&K curve due to some vagaries of the TacT that I'm not sure I fully understand.

Marty, I understand that the target is the desired curve at the listening position and is not necessarily congruent with the actual, measured curve at that position, given the laws of physics and filter limitations. What are you using to determine the actual curve - the TacT's calculate function or a 3rd party RTA?

Ken

 

[marty]

Ken,
I understand. You have to start somewhere. I used a fairly standard TacT curve. Any number of them will serve as a a good starting point. I think I used QS25G.COR, or something like it. For Gothams and Pipedreams I chose a 90Hz crossover point with maximum symmetrical steep slopes (24th order: 144dB/octave) on each side. Setting up a biamped system on the TacT is a bit trickey. The main prerequisite is to set the gain of both the subs and the mains using the TacT prior to performing EQ, so the SPL output of each is approximately equal at the crossover point to begin with. If you don't do this you will have some weird shelves in the target curve that are even weirder than those already present in a "typical" target curve such as the QS25G.COR. Oh, and contrary to other notes I've seen on this forum, there is indeed a manual for the 2.2XP and the set-up instructions are pretty decent. The manual may be downloaded from the TacT web site. What the manual does not cover however, are complexities such as using JL Audo subwoofers. Here, Anthony Padilla was a tremendous help. He figured out that you have to EQ the JL subs first the way JL instructs you, prior to doing anything with the TacT.
Marty

 

[TacTical]

Marty, the most important thing to do with setting up a JL subwoofer in ANY SYSTEM, is to be sure to use the least amount of volume allowed for the test tones, to be able to complete a successful room corrected calibration. When you use the least amount of volume to complete the room correction with a JL Sub, the Sub correction will be so much flatter than using a high volume level for the test tones. If you use the highest volume setting allowed to complete the room correction, the SUB will not be flat at all, it would be about -/+ 25db from 25Hz to 120Hz. At the lowest volume setting, you get about -/+ 5db from 25Hz to 120Hz. If you use a TacT RCS and apply its room correction after you done the sub correction, it will be ruler flat across 20Hz to 20Khz.

Oh yea, almost forgot... before applying TacTs Room correction make sure to adjust the volume on the sub to mach your main speakers output level. You can use TacT measurement test pulses to determine equal balance between your subs and main speakers. After the Jl Subs are Response is corrected and the JL Subs volume is adjusted equally to your main speaker volume, then apply the the TacT room correction.

A good crossover slope for the JL subs is to use a forth order high pass (24db) and use a second order slope for the low-pass (12db) with a 5HZ gap at the cross over points. For example: use a 24db (forth order) high pass at 80Hz with a 12db (second order) low pass at 85Hz. This is one of the many reason why I like TacT so much. Its the ONLY unit I ever used that was able to perfectly seamlessly integrate subs in to my audio systems. All without being peaky or weak sounding on various types of music.

Anthony
Digital Done Right!
Mauimods.com
TacTaudio.com

 

[TacTical]

Marty, I just re-read you post about using maximum symmetrical steep slopes (24th order: 144dB/octave). From my testing, using 24th order slopes can be very demanding (and destructive) for your subs mains, and amps. Listen to your Subs play without the mains at a good level. You should be able to hear what I am talking about.
Anthony