4343' S On The Way!

[Triumph Don]

My 4343's are finally on the way [any one interested in the 300's?]. I have an old Crown VFX-2 crossover that just tested great. The plan is to bridge 2 DC300A's to mono for the lows, a McIntosh 2205 for the rest. Having never undertaken a bi amp project, any and all inputs/ideas/warnings would be greatly appreciated!

[4313B]

Congratulations! :)

[scott fitlin]

You are gonna love that crossover!

[rgrjit8]

RELIGIOUSLY follow good turn on/turn off sequence with that crossover.

Then again, I promise you'll only make that mistake once.

[scott fitlin]

You might want to use the 1/4 inch balanced inputs, because you have user adjustable gain, and this will compensate for any insertion loss. You have screwdriver adjustments on the back, allowing you to go from unity gain up to +15.5db. If you use the unity gain inputs it might be too dead sounding. Both your amps have input level attenuators, and you will have to balance the level between high/mid and low from here as the VFX has no output level attenuators.

Jus my .02 cents!

:cool:

[subwoof]

If you find a JBL 5234 with correct cards, it has a turn-on delay so the whole system can be turned on/off at will.

In addition the power switch on the crossover works great as a mute ( since we all know how quiet these will be listened to...)

Plus offsetting the VFX filters by the exact amount on both channels is gonna be hard without good test gear ( LP appox 290, HP appox 320 )...

Those controls are 20% tolerance pots and the print is only as accurate as the guy who put the knob on....!

sub

[boputnam]

Originally posted by subwoof
Those controls are 20% tolerance pots and the print is only as accurate as the guy who put the knob on....! :yes: :banghead:

A subwoof truism...

[Chas]

Speaking of the VFX, I had one years ago. Maybe they were upgraded later, but mine had horrible 741 type quad op-amps and very wimpy power regulation.

At the time I added 7815/7915's, better filter caps and decoupling and TLO74's because it was the best thing to do in those days. I'm sure there are way better quads today, just be careful - wide bandwidth opamps can be a devil if installed in PCB layouts that are not layed out to accomodate high performance chips. We used to call it "green screen" when the HF oscillation was viewed on a'scope.

If you want to be safe, the TLO's at least, were a huge improvement.
C.

[subwoof]

Agreed on those quads - someone once sold a 14pin socket with .01 CK5's embedded for decoupling the rails. Great for quicky upgrades.

Those VFX's had none - and the 4 pin regulators ( they were the ONLY manufacturer that used them ) were noisy + could not handle the current. I can't tell you HOW many PSA2's failed because of them.

I think the OP09 also worked BUT the pinout was set to the "other" quad standard???

[Ian Mackenzie]

The last VFX I took the list off had 5532's in it, a bit ancient but a well engineered unit and quite clean for a crossover.

I would tend to have the crossover always on, saves expensive recones. Try them passive just for comparison with the McIntosh 2205, it may sound smoother in some respects.

Ian

[Ian Mackenzie]

All electronic crossover tend to scrub the sound to a certain degree (despite the tighter sounding bass.)

The additional buffer stages, often 4-6 stages add successive noise and distortions. The buffers tend to configured for unity gain with 100% negative feedback which these days is considered a no no for top audio performance.

However years ago most power amps had lousy intermodulation distortion and TID anyway and bi amping cleaned this up a lot and was preferable to 60 uf of Myler caps in series with the mid cone in passive mode.

New crossover parts and better amps, well who knows?

When the parts arrive I will dish up a proto type mini version of this for you guys to try. No I.Cs, full discrete regulation.

Full balanced in and out or unbalance in and out, discrete class A buffers biased to about 10 milliamps (TL074s are AB) with low feedback, the regulator will have 42000uf of passive CRC filtering and zero feedback mosfet series regulators.

I think it will be good.

Ian

[Chas]

I think the OP09 also worked BUT the pinout was set to the "other" quad standard???

Hey, subwoof, I think you jogged my memory cells a little bit, come to think about it, maybe they were an oddball pinout. I think I used TLO75's. Anyway, same family.
C.

[scott fitlin]

Originally posted by Chas
Speaking of the VFX, I had one years ago. Maybe they were upgraded later, but mine had horrible 741 type quad op-amps and very wimpy power regulation.

At the time I added 7815/7915's, better filter caps and decoupling and TLO74's because it was the best thing to do in those days. I'm sure there are way better quads today, just be careful - wide bandwidth opamps can be a devil if installed in PCB layouts that are not layed out to accomodate high performance chips. We used to call it "green screen" when the HF oscillation was viewed on a'scope.

If you want to be safe, the TLO's at least, were a huge improvement.
C. Yes, the TLO series op amps are an improvement over those 741,s. But, the TLO84 is a better sounding IC than its low noise counterpart, the TLO74! The 84 has better presence and a more solid sound!

I know Im gonna get shot for this, but its my honest opinion!

:cool:

[Ian Mackenzie]

Scott,

If you are keen to play with drop in chips on the fly, try the BurrBown opa 2134s or the 2604.

Analogue Devices also have some new chips, just make sure they are Fet input (input low offset).

However the best chips are no chips.

I am hopeful of hearing an XV1 Passlabs crossover in a week or two (as above). The proof will be in the pudding.

Ian.

Ps I wonder if Bo's back door is blue?

[scott fitlin]

BB IC,s are very good and extremely accurate. They do sound different from TLO chips. Yes, I agree that Jfet or FET input is the way to go.

I have several BB IC,s on hand as well as Analog Devices. And still, for one reason or another, I like the way the TLO84 sounds.

Discrete circuits are the best, and the most expensive. Brystons xovers are all discrete and very clean, yet still maintains warmth, and is exceptionally accurate.

Im interested in your xover, Ian, if you can configure some custom stuff in it for me.

:cool:

[Ian Mackenzie]

Exactly,

The TL074 are a cross b/n the all fets stuff like the 2134 and the 5532, firmer bass but still smooth. It depends on the application, if you needs gain and drive , the 5532 are the bees knees as no at all expensive and easy to use.

The beauty of discrete buffers is they can be optimised for the task at hand, unlike the generic opamps.

I plan to set up a design for our 43xx & 44xx monitors, fixed crossover points with idealised voltage drives as required, minimalist stages with high quality parts and a 2/3 way version with full adjustability for those who like to mix and match drivers.

The Bryston stuff is excellent, I anticipate this will in the same league.

Should have something tangible on the table by summer.

Ian

[scott fitlin]

I have a crossover, my RLA X-3000, that uses TLO72,s and other engineers upgraded to the 5532. Its a simple plug in procedure and the 5532,s are inexpensive. The sound using the 5532,s does have drive, but is not as sweet sounding as the TLO72.

My Urei 1620 and Urei 525 uses either the TLO74 or 84. The TLO84 sounds the best to me because it has a solid presence and oomph and growl on the bottom. I gone back and forth a thousand times, and I have learned what it is I like.

I substituted BB ic,s for the TLO74/84,s in the Urei, pinouts are identical, so its a simple procedure, and heres what I hear each time I try them. The bass is firmer using BB ic,s and there is more definition. But compared to the TLO84 it sounds rolled off in the extreme bottom. The midbass and midrange have very solid presence, but is too forward for my taste. The TLO,s are more laid back and give the illusion of depth. The BB ic sounds coarse in the top end. This I truly DID NOT care for. The TLO84 has a pleasant coloration that I DO like! My opinion is that there are in fact components that sound very exact and are highly accurate, more so than things from the past, but, for whatever reason, make music not as fun to listen to. The BB ic,s remind me of the CURRENT high end sound. Analytical, ruthlessly revealing, very accurate, and very boring! This is my particualr take on things, and no one has to share my exact veiws on things, but its how I do!

Years and years of doing audio, both for entertainment ( buisiness ) and home listening, I have come to the conclusion that while we do have the ability to keep all forms of colorations and distortions to a very bare minimum, its not always totally beneficial! Certain things make music sound realistic, natural, and enjoyable.

Again, I am not knocking anybody for what they do or do not like, this is just one mans opinion!

:cool:

[Chas]

Well, this thread is going way off-topic and I may start some flames here...... maybe we should move out of here....
Personally speaking, a well laid out design with high performance op-amps, low impedance well regulated power, etc. can sound as neutral as any discrete or tube circuit.

Now I'll run for cover:slink:

[John]

Well its like the food we eat,we all try to cut out the fat and eat healthy. But it tastes like crap!!!:biting: