Raising the While Flag on 604 Project

Quote:

---

Originally Posted by vuki

Anyway - as Panomaniac said; buy the cheapest parts for my crossover (ferrite inductors, wirewound resistors and MKT caps or even bipolar elcos) and put it together "in the air" - you don't have to solder- use screw terminal strips if you like.

---

Thanks vuki! I'm going to give your XO a try, and order the parts today, but I need some help on the parts list, as I'm unfamiliar with some of the resistor and capacitor values. Let me know if this parts list is accurate. I put a question mark where I'm unsure:

Caps
C1 = 2uf
C2 = 15uf
C3 = 6uf
C4 = 15uf

Inductors
L1 = 3.6mh
L2 = 0.82mh
L3 = 1.2mh

Resistors
R1 = 18 ohm
R2 = 33 ohm
R3 = 4.7 ohm
R4 = 27 ohm

I'm assuming that LSP1 and LSP3 are the + speaker leads, and LSP2 and LSP4 are the negative speaker leads. Is this correct?

Also, it's been mentioned that certain parts can be exchanged for different values to change the sound. Which parts are they, and should I buy different values to experiment?

Finally, can an L-Pad be installed in this design, and do you recommend for or against it?

Thanks, and sorry for all the questions... :)

Capacitors:
2,2uF
6,8uF

You won't find 3,6mH inductor - buy 3,9mH and than unwind few turns of the wire (it will work with 3,9mH, but it will be a bit lifeless).

The rest is OK.
LSP's - correct.
You can vary the value of 4,7Ohm resistor to get more or less hifreq energy - buy additional 3,3 3,9 6,8 Ohm resistors. Or you can instead of the 4R7 resistor install 8R section of L-pad, but I would go with resistors.

:2thumbsup:

Wow this certainly is something to make a guy wonder about these drivers now.. For a pair of loudspeakers that are touted by many to be the best of their kind ever made, it really shouldn't be this hard, especially considering the significant price tag!

What gives? It really shouldn't have to be rocket science should it?

I've been sitting on the fence for awhile now waiting and trying to find out as much info as I can, now I'm happy to not have ordered as of yet..

Hope all this effort, money and frustration works out for you in he end!!

:)

Hi :waver:,

I just finished soldering Jeff Markwart's "Simplified 604-8H EQ Crossover" for my 604K in 620 cabinets (with L-pad). In my humble opinion a significant lift compared to the stock crossover. Much less shoutiness (possible to fine-tune with L-pad). I used Solo Inductors and Vampire Hook-Up wire but substituted the Hovland caps for Russian NOS paper in oil capacitors including the teflon FT3s for the high-pass part. To help low end I also use a powered sub (mono). Very satisfied.

Naimare

Quote:

---

Originally Posted by DaveCan

It really shouldn't have to be rocket science should it?

---

I haven't measured a pair, but I tend to think the drivers are awesome, though I'd echo others' wishes for a larger horn; what people are really moaning about are the crossovers -- which can be awfully difficult. Designing a crossover that everybody will be happy with is impossible.

Despite a poor first impression, I still comtemplate picking up a pair from time to time.

Regards,
John

Hello all.... feel it's time to chime in with my $0.02 worth.....

I have designed many crossovers variants for the 605A, 604E & 604-8K. The 605A and 604E's were basically stock builds, 8K's were a 1983 16X chassis re-worked by GPA into a 8K configuration. They did a great job BTW!

With these high performance... high efficiency duplexes very slight crossover differences can make a HUGE difference in sonic out come. Do not have the time to discuss my beliefs on why that is now. Maybe a later topic.

I have noticed a couple of things of importance...

How the woofer is loaded ... type - size of enclosure... or... no traditional enclosure as in OB or Cardioid is the first thing that has to be settled... and fine tuned BEFORE serious crossover work can be undertaken. The bass qualities of say the 605 are very different if operated in a sealed box, IB or vented.... let alone OB or Cardioid... and this is significant with the woofer cone having to contribute up to about 2 KHz.

And.. second... it really helps to have a first class reference during crossover fine tuning. That is a reference speaker that you find to be to your personal liking. It is so easy to end up chasing sonic artifacts too far before realizing where you're going is not helpful. Taking measurements helps during the tweaking (voicing process if you will) but measurements alone usually will not get you to where you need to go.

I am fortunate in that I have tons of parts... inductors, capacitors, audio grade resistors, L pads and so on as well as various sized test boxes and baffles. Plus working with crossovers for 50 years doesn't hurt either. With all that said... getting the duplex's to sing is not an easy task. But... when you get there... there are few systems that can do what these duplex's can do. Which is why they are... for many of us, worth the trouble... effort.

I have worked with Jeff Markwart's designs and they are very sound... no pun intended. Way closer than most other designs I have seen published and tried. Including nearly all Altec developed designs. His understanding the raw characteristics of these drivers and using frequency spreads to help maintain phase through the band pass is key to solving the shout and other problems so many comment on. These are Thoroughbred drivers that demand special care and attention... but like a Thoroughbred can deliver like no other.

An example of the effectiveness of Jeff's 605A work (with some personal modifications for OB operation in a small room) can be found here:

lone star audio fest 2008 and here Lone Star Audio Fest 2008 - Event Reports - Dagogo

Many were amazed by the dynamic yet smooth presentation as well as excellent imaging this set up provided. Plus the ability to play at live levels without a hint of strain.

It can be done.

Quote:

---

Originally Posted by DaveCan

Wow this certainly is something to make a guy wonder about these drivers now.. For a pair of loudspeakers that are touted by many to be the best of their kind ever made, it really shouldn't be this hard, especially considering the significant price tag!

What gives? It really shouldn't have to be rocket science should it?

I've been sitting on the fence for awhile now waiting and trying to find out as much info as I can, now I'm happy to not have ordered as of yet..

Hope all this effort, money and frustration works out for you in he end!!

:)

---

This is what I was starting to think it shouldn't be this hard.The only differance that I can tell and from talking with Bill is between the 604-8H II and the 604-8H III is that the III is supposed to extend alittle higher to 22 khz were the II reaches 20 khz.

They are both beautiful sets of drivers what has become quite obvious is the problem lies in the Crossovers for these Beauties.Once these issues can be worked out everyone I know or have spoke to couldn't be happier with them but man to get there WTF can be a bitch.But the final outcome of these drivers is WORTH THE EFFORT!!! And all the people I have talked to about this say at the end that they think they have arrived at the speaker they have been looking for,for good. :) So the rewards could be great, everyones preferance is differant and what the L-pads try to accomplish I think is to appease the masses to fine tune to everyones liking tone up or tone down.

I'm very interested in this thread as I'll be in the same boat maybe when I start to build new cabs for my 604's come this spring when it warms abit.I hope you can come to a quick resolution with this and don't give up on such a nice set of drivers,cabs,etc..

Seadweller may you have some "Great Luck" in the near future I HOPE !!! ;)

With all the great talent on this board you are in GREAT HANDS ~ GOOD LUCK !!! :2thumbsup:

Not to step on Seadweller's thread....

But I was thinking about connect an lpad to my GPA XO's to maybe find a sweet spot for my 604's...

Where would I place it?

Thanks,


-chris

Quote:

---

Originally Posted by Seadweller

Thanks GM.

........or even more likely, that the excessive midrange energy is masking it.

Honestly, if worse comes to worse, I could add a subwoofer to the system..........

........there is a range of frequencies that when a voice or instrument fall in that range, the beaming is like the phaser on the Enterprise.

Actually, for my own curiosity, would a passive radiator mounted in the bottom of the cabinet be an option? Or how about an active driver?

---

You're welcome!

Which can be caused by a leaky cab rolling off all the bass.........

Well, I'm not there and for sure if there's a hump in the horn's response it can sure sound this way, but I find it hard to believe that this would occur with JM's XO assuming it has the adjustable pots to dial it in.

PRs have a compliance measured in the hundreds of liters, so they can only be vertically oriented, same as most Altec drivers, including the 416.

Adding a driver to a given cab effectively reduces the air mass spring each driver feels, so F3 goes up and Fb normally must go down to keep it from sounding 'boomy'. In short, it will have ~ a half octave less bass response.

GM

Quote:

---

Originally Posted by oface1

But I was thinking about connect an lpad to my GPA XO's to maybe find a sweet spot for my 604's...

Where would I place it?

---

Got an accurate schematic?

GM