Modified Forte 1 Upgrades-Bob Crites Autotransformers and Titanium Tweeters

maybe the 15" passive on the II as opposed to your 12" passive on the original Forte'???...I have yet to hear this speaker (either or the Chorus/Chorus IIs) but REALLY enjoy my Quartets (tractrix instead of exponential...more like IIs but no differences in Quartets)
Bill
 
maybe the 15" passive on the II as opposed to your 12" passive on the original Forte'???...I have yet to hear this speaker (either or the Chorus/Chorus IIs) but REALLY enjoy my Quartets (tractrix instead of exponential...more like IIs but no differences in Quartets)
Bill

They should be tuned to the same frequency in virtually the same size box to get the same F3 point. The "Q" could be slightly different with the 15".
 
The Forte II is indeed a little forward, I have been wanting to buy some autoformers from Crites and take them back a tap. Out of the box, the original Forte sounds better than the Forte II.

The K-23-K and K-25-K are virtually identical, the only difference is the K-25-K out of the Forte II has a vented voice coil.
It is interesting that Klipsch rates the Forte at 98dB 1 watt and the Forte II at 99dB 1 watt with same bass extension. I think it is the Forte II horn being a little hotter.

:yes: I would agree, After looking at the Forte 1, Then Forte II then looking at the Chorus II which uses the same mid-range k-61-k as the Forte II.

It appears that the Chorus II is using a substantial amount of attenuation that the Forte II is not apparently using. And the Chorus II is at 101db/watt vs the 99db of the Forte II or the 98db of the Forte 1

chorusiicrossovergc4.jpg


All three are using different Auto-transformers I can't get to Bobs site to verify the exact attenuation's of the transformers as it appears to be down.

:scratch2:I wonder if Bob has done anything with the Forte II issue as I think he offers 2 versions of some of these networks.

SET12
 
:

It appears that the Chorus II is using a substantial amount of attenuation that the Forte II is not apparently using. And the Chorus II is at 101db/watt vs the 99db of the Forte II or the 98db of the Forte 1

All three are using different Auto-transformers I can't get to Bobs site to verify the exact attenuation's of the transformers as it appears to be down.

:scratch2:I wonder if Bob has done anything with the Forte II issue as I think he offers 2 versions of some of these networks.

SET12
I do not think Bob modifies the crossover, just builds new units to the same values.
The Forte II autoformer provides 10dB of attenuation, and i am not sure what the chorus gets having the autoformer set at -6dB and the resistor in series. It would be cool to try to get the Forte II notched back a little bit more, 1 or 2 taps with one of Bob's autoformers, but then we would have to know what to change the cap to to keep the crossover at the same point.
 
I do not think Bob modifies the crossover, just builds new units to the same values.
The Forte II autoformer provides 10dB of attenuation, and i am not sure what the chorus gets having the autoformer set at -6dB and the resistor in series. It would be cool to try to get the Forte II notched back a little bit more, 1 or 2 taps with one of Bob's autoformers, but then we would have to know what to change the cap to to keep the crossover at the same point.

Your correct alteklipsch,

I guess I got cross eyed with all the networks :D

When I talked to Bob about the forward midrange some feel that the Forte II may have, he had said he had not heard of it. But I have heard some reports myself.

Interestingly the stock LaScala's mid level is also found to be high by some including myself. When adjusted using the ALK network I found them to be much more involving with a substantial increase in their bass performance.

I am quite taken back at just how much system tuning can be done to the low,mid,and high frequencies with the individual network components, much like choosing various amplifiers and such, pretty amazing!

As far as the Autotransformer values here's Bob's list.

T2A(3110A) -3, -6, -9, -12db

T3A(3465-M) -6db

T4A(3485) -4db

T5A(3496) -6db

T7A(3504) -10db

T8A(3507) -8db

T9A(3540) -3db

T10A(3542) -9db

T11A -12db



The Forte uses the T7A

Forte II the T10A

Chorus which uses the same mid-range driver as the Forte II the T5A

Bob Crites has available 3 different autotransformers that can replace the above.

I might add that their construction nearly 50% larger are worth every penny for their increased bandwidth and substantially increased sense of space and effortlessness make them very well worth the cost IMO.


I recently had some trouble linking to his site for a few days a long with a couple of my friends using the same internet service and after conferring with Bob, He checked with his site provider and everything was good on his end. He suggested I check with ISP Support and as I was in the process I noticed my provider Time Warner Cable has a program called Road Runner Medic 6.1 to diagnose and fix a variety of issues such as connectivity of which it appears my cable modem had some issues. It sure worked cool!

Its this kind of communication that will keep me recommending Bobs work and service.

So, Thanks again Bob! :thmbsp:

SET12 :smoke:
 
Good information on the autoformers, thanks for posting it. I think one of the units Bob has allows 1.5dB steps which would be perfect for fine tuning.

If you ever have a chance to compare the Forte and Forte II side by side I think you will see what I am talking about on the Forte II being too forward. I have had many friends over that have chosen the Forte over the Forte II in blind listening tests. The mid horn in the Forte II is superior to the Forte unit, but falls short do to poor crossover integration.
However, if someone does not think a LaScala is not too forward, they probably would prefer the Forte II over the Forte. I had my LaScalas hooked up a few weeks ago but only left them in for about a day. In stock configuration they are a little too hot for me.
 
Good information on the autoformers, thanks for posting it. I think one of the units Bob has allows 1.5dB steps which would be perfect for fine tuning.

If you ever have a chance to compare the Forte and Forte II side by side I think you will see what I am talking about on the Forte II being too forward. I have had many friends over that have chosen the Forte over the Forte II in blind listening tests. The mid horn in the Forte II is superior to the Forte unit, but falls short do to poor crossover integration.
However, if someone does not think a LaScala is not too forward, they probably would prefer the Forte II over the Forte. I had my LaScalas hooked up a few weeks ago but only left them in for about a day. In stock configuration they are a little too hot for me.

I know!

But if you were to use these ALK networks you won't be unhooking them :tears: real fast IMO. They literally become a whole different animal! :music:

This network that allows you to adjust the midrange level to your taste. Its the constant impedance of this network that allows you to change mid levels by changing the taps which brings everything else including generous bass into proper perspective from my experience.

After hearing my buddy's LaScala's with a DIY version of this network I decided to mod mine.

That listening experience was very profound for me!:yes:

Here's all the necessary imfo at Al's website.

http://www.alkeng.com/ap_xo.html

The actual network schematic!

SCHEM ALK.GIF
 
I know!

But if you were to use these ALK networks you won't be unhooking them :tears: real fast IMO. They literally become a whole different animal! :music:

This network that allows you to adjust the midrange level to your taste. Its the constant impedance of this network that allows you to change mid levels by changing the taps which brings everything else including generous bass into proper perspective from my experience.

After hearing my buddy's LaScala's with a DIY version of this network I decided to mod mine.

That listening experience was very profound for me!:yes:

Here's all the necessary imfo at Al's website.

http://www.alkeng.com/ap_xo.html

The actual network schematic!

View attachment 102947

Agreed, with stock networks, LaScalas and Belles were always very top heavy - and to me - unlistenable. Just tons of midrange and a #$%^ tweeter with no bass. I've had two different versions of Al's networks (ALK Universal and Extreme Slope tops/Gentle bottoms), and Al makes some great stuff. LaScalas and Belles become different speakers once you are able to balance out the speakers and bring the midrange (and tweeter) down. At times, I have attenuated the midrange on my Belles anywhere from 8 to 12 db down, and usually attenuate the tweeters about 7 db.

I also agree that the Forte I is more balanced than the Forte II for the reasons previously discussed.
 
This past weekend I attended a Klipsch Palladium P-39F listening session which you might want to follow a bit.

http://forums.klipsch.com/forums/t/107454.aspx

These were the first pair sold in North America they are Klipsch's latest Engineering effort and are very good IMO.

While I wasn't over whelmed I was neither under whelmed.

What I found interesting is how well the Forte's with these modifications can compete with the Pal's.

Its hard to say how far the Pal's can perform with my brief listening session with them but I know they are very capable of holding ones attention especially with today's high-end electronics.

I get to some specifics later.

One thing for sure though that I really learned to appreciate is the perspective of DIYings worth!

And that is for every dollar spent it can really be worth 10 times that in retail value!

SET12 :smoke:
 
This past weekend I attended a Klipsch Palladium P-39F listening session which you might want to follow a bit.

http://forums.klipsch.com/forums/t/107454.aspx

These were the first pair sold in North America they are Klipsch's latest Engineering effort and are very good IMO.

While I wasn't over whelmed I was neither under whelmed.

What I found interesting is how well the Forte's with these modifications can compete with the Pal's.

Its hard to say how far the Pal's can perform with my brief listening session with them but I know they are very capable of holding ones attention especially with today's high-end electronics.

I get to some specifics later.

One thing for sure though that I really learned appreciate is the perspective of DIYings worth!

And that is for every dollar spent it can really be worth 10 times that in retail value!

SET12 :smoke:

The Forte sure is the little engine that could. They are a true audio bargain. I have made up my mind based on your crossovers to do a stock vs. modified shootout when I get my crossovers done. Should be fun and informative.
As for the palladiums... I think I know what you are getting at. Multiple small woofers never get it done for me. Anything less than a 10" does not seem to have much slam. When I was shopping around for RF series I had the chance to compare the RF-7 to the RF-83, the RF-7 won hands down in my book.
 
I've had two different versions of Al's networks (ALK Universal and Extreme Slope tops/Gentle bottoms), and Al makes some great stuff. LaScalas and Belles become different speakers once you are able to balance out the speakers and bring the midrange (and tweeter) down. At times, I have attenuated the midrange on my Belles anywhere from 8 to 12 db down, and usually attenuate the tweeters about 7 db..

Al has stated he'd be willing to design an network specifically for the Forte, but he hasn't had access to one to take the required measurements he uses for their development. Apparently there's no one near Baltimore willing to let Al borrow one of their Fortes for a couple hours. Actually, anyone who knows how to take the measurements themselves can just submit them to Al and he can go from there.

I don't mean to sound petty, but after all the work I've put into my crossovers (and as good as they sound), the fact that there's even more waiting to be squeezed out of them kinda drives me nuts.

-Brinkman
 
Al has stated he'd be willing to design an network specifically for the Forte, but he hasn't had access to one to take the required measurements he uses for their development. Apparently there's no one near Baltimore willing to let Al borrow one of their Fortes for a couple hours. Actually, anyone who knows how to take the measurements themselves can just submit them to Al and he can go from there.

I don't mean to sound petty, but after all the work I've put into my crossovers (and as good as they sound), the fact that there's even more waiting to be squeezed out of them kinda drives me nuts.

-Brinkman

Brinkman, Please don't feel bad! It doesn't mean that if he came up with something that it would obsolete what you have! Or be terribly better!

An example is the Engineering that went into the $20,000 Palladium's while they are very good I didn't walk away with my head bowed and eyes looking at the ground! To the contrary I had a smile!

And I can tell you I do know what it feels like to lower ones head! I once spent 3 yrs on and off designing math and all, a scratch Tube Phono Preamp before it would beat a well designed SS Phono that a friend of mine had.

The nice thing about the Forte 1 is that it has a reasonable good balance, its network has low value parts that has allowed me to use the parts that I have which make the Forte such a bargain for the results that can be had as mine.

When you look at some of the other networks with high values it can get quite expensive to do what I have done quality wise with the Forte 1. Of course what one calls quality can be debated. But never the less parts values can be equated to cost. And the ALK networks have high values and more parts.

Though his networks are very effective. Its the subjective tone and harmonics that are affected by the passive parts that I'm really interested in.

I also went through caps and inductors to the tune of $300 plus in this venture. Which I will simply resale or use elsewhere.

Even if ALK came up with a dynamite network you'd likely be able to use many of the parts.

But overall I'm very impressed at my results with this network.

And after hearing the Palladium's the Forte's are like the little horse Seabiscuit of the 1930's running among giants with the same enthusiasm.

See the movie! And you'll know how I'll feel!

SET12
 
The Forte sure is the little engine that could. They are a true audio bargain. I have made up my mind based on your crossovers to do a stock vs. modified shootout when I get my crossovers done. Should be fun and informative.
As for the palladiums... I think I know what you are getting at. Multiple small woofers never get it done for me. Anything less than a 10" does not seem to have much slam. When I was shopping around for RF series I had the chance to compare the RF-7 to the RF-83, the RF-7 won hands down in my book.

My self through the yrs have had some real surprises as to woofer size vs low end response!

I have been fortunate to of been introduced to some amazing mini-monitors like the ProAc Response Two's with just a 6.5" woofers. And others under 8"

The bass has to be heard to be believed. A friend of mine owned a pair of these for a few yrs. He once tried integrated an expensive sub to them. But took the sub back because the sub just wasn't adding much and basically got in the way of an already excellent low end response!

http://www.stereophile.com/standloudspeakers/792proac/index1.html

Another that just floored me were the Odyssey Lorelei

http://www.odysseyaudio.com/loudspeakers.html

These things I heard at an Audio Show in Lima Ohio some yrs back! they were at least 6ft away from any walls and I looked all over for a sub cause my jaw was on the floor, literally an amazing speaker!

Another and the most expensive $12,500 in 1992! The Sonus Faber Extrema

http://www.stereophile.com/standloudspeakers/915/index.html

Huge sound stage with some of the finest bass I have ever heard.

While I found all of these great speakers bettering the Forte's in many area's they do not overwhelm the Forte's level of involvement that they can give with the likes of a mere 5-10 watts. And for me the best Harmonics I have heard have been from 10 watts or less.

I might add that when I heard the Palladium's with a 200 watt/channel SS amp the Modified Forte's came across as subjectively substantially more authoritative with 10 watts but not subjectively as accurate at pitch definition.Yet the Forte does surprise often as to "where did that come from syndrome"

SET12 :smoke:
 
Brinkman, Please don't feel bad! It doesn't mean that if he came up with something that it would obsolete what you have! Or be terribly better!...
Even if ALK came up with a dynamite network you'd likely be able to use many of the parts...

I had been holding out for a Klappenberger Forte network for a while before I gave in and did the complete crossover makeover this thread is in regards to. But even if it's a while down the road before a network appears, the prospect that the parts I've already acquired would be re-used is a relief.

What really sold me on the Forte was not just that it mated well with tube amplifiers and could deliver effectively for a variety of musical genres, but that it is well-balanced, has considerable bass response and a very good sensitivity rating. So there's many reasons to want to push it to the limit. And one feels even more compelled if they're into DIY.

When I'm finished with my next three projects I'll have a refurbished/replinthed Lenco turntable, a kit-based phono pre-amp and a kit-based line stage as well. That's a lot of critical listening to perform on components with substantial time invested in them, so the Fortes were the logical first step towards an eventual progression of (hopefully) well-balanced, quality builds.

As an aside, I wanted to mention how much I like the EH 6CA7 fat bottles in my modified ST-70. Before the Forte makeover I found them thin and lacking extension and preferred the robustness of the Winged =C= EL34s and the warmth of the JJ KT-77s. With the extra clarity of the new crossovers, the 6CA7s have dynamic, balanced sound that leaves little to be desired.

Looking a long way down the road and the eventual DIY monoblock project is going to be a lot of fun...

-Brinkman
 
awesome, can't wait to see a shootout

I have a friend just down the road that has a pair of stock Forte's I think its time again for another serious comparison as its been awhile since I've had a stock pair here and I haven't done a side by side comparison since these last up grades it should be interesting so I'll see as to when I can get them here :yes:

I had been holding out for a Klappenberger Forte network for a while before I gave in and did the complete crossover makeover this thread is in regards to. But even if it's a while down the road before a network appears, the prospect that the parts I've already acquired would be re-used is a relief.

What really sold me on the Forte was not just that it mated well with tube amplifiers and could deliver effectively for a variety of musical genres, but that it is well-balanced, has considerable bass response and a very good sensitivity rating. So there's many reasons to want to push it to the limit. And one feels even more compelled if they're into DIY.

When I'm finished with my next three projects I'll have a refurbished/replinthed Lenco turntable, a kit-based phono pre-amp and a kit-based line stage as well. That's a lot of critical listening to perform on components with substantial time invested in them, so the Fortes were the logical first step towards an eventual progression of (hopefully) well-balanced, quality builds.

As an aside, I wanted to mention how much I like the EH 6CA7 fat bottles in my modified ST-70. Before the Forte makeover I found them thin and lacking extension and preferred the robustness of the Winged =C= EL34s and the warmth of the JJ KT-77s. With the extra clarity of the new crossovers, the 6CA7s have dynamic, balanced sound that leaves little to be desired.

Looking a long way down the road and the eventual DIY monoblock project is going to be a lot of fun...

-Brinkman

I just might have to contact Al.

Yes, I to like the EL34 family and the 6CA7's.

What were you thinking of for a mono block project?

Also would you care to try a little experiment?

Would you like to hear the Punch Factor of you amp go up?

Yank out that choke or put a jumper across it!

I myself don't use them cause of the usually high DCR 100 ohms is very audible and I would think 60 ohms would be to! Which is the dyna's stock DCR value.

If I were using a choke it would likely be lest than 20 ohm's like
Herb Reichert here, just read about the sheer current reserve he uses!:yes:
Its my next step!

http://www.enjoythemusic.com/magazine/equipment/0801/fleshandblood.htm

Since the amp is PP you shouldn't have to much of a signal to noise increase and if you liked what you heard but wanted it a little quieter you can just add more capacitance. I assume your using a slow turn on rectifier like the 5AR4, and as you probably know newer versions have not been meeting the slow turn on spec so NOS is best.

I like to use Diodes to drop supply noise over in my B+ supplies. I also use electrolytics as bulk then branch off with another diode to feed Solen Poly Props the diodes highly isolate the Solens in my SET mono's each of which run on 1800 uf of electrolytic bulk then feed to 22uf of Poly Prop for the output stage (when I think about it I might increase it) and 12 uf for the driver stage. Can you say nil for DCR? I can

Which is part of the reason that the Forte's here do have a leap factor.

Usually a supply this big does not sound to good. But even with this much electrolytic it sounds like a literal prop supply. Very very transparent.

I do feel compiled describe my amps a bit simply because they are contributing to the Forte's.

Also I use the C4S current source loading for the driver stage which can lower the distortion vs a resistor plate load to as much as 300% lower. Also I don't bias with resistors I use LED's I can thank Dennis Had of Cary Audio for that trick!

And the last trick since my amp runs in Class A2 it is design to run on "0" volts bias and knowing the effect of resistors vs LED's I used a pair of diodes to connect the directly heated triode filament to ground. The punch factor increased so much from this connection that I got a call from my duplex neighbor that her pictures where moving on her walls! That was with two garages between our living rooms.

So these are some very powerful SET amps and its important to know that ones mileage will vary from these Forte mods with associated gear but I'm sure you all very much know this!

This hobby sure is fun!

SET12 :smoke:
 
Contacting Al could only be beneficial to Forte owners. Here's some threads where he outlines his measuring approach. Be forewarned, they're technical:
http://www.audiokarma.org/forums/showthread.php?t=93064
http://www.audiokarma.org/forums/showthread.php?t=133037

I am slowly working my way through my Hi-Fi chain with hand-builds, the current one being a USB-equipped phono pre-amp (for digitizing vinyl) and following soon after that a tube-based line stage. When they're done, I'll do a replinthing/refurbishing of a Lenco and then, maybe build a pair of wide-bandwidth, Class A1 Push-pull monoblocks using CCS and no global feedback. Hoping for maybe 50 watts a side. We'll see.

I might eventually try your choke experiment on my ST-70; for the moment I've got my hands full with my ten-month-old and am anticipating going back to school in the fall (for engineering). On top of all that, I'm broke.:dammit:

Best.

-Brinkman
 
Brinkman, Thanks for the links!

Let me know if you try the dyna trick.

For those that might want to try this especially with EL84 amps as I have done with my friends Pilot based 84 amp in the same fashion as the Eico

Here's the schematic of the Eico HF81 notice how the center tap of the primary of the output transformer is tied directly to the rectifier output and its first cap then the screens are fed from a 350 ohm resistor.

I believe this a good part of the Eico's slam factor :yes: as I was quite shocked at the resulting sound yrs ago before I ever saw the Eico schematic.

The Eico btw is not Ultra Linear connected of course. But is in Pentode Mode which I like for dynamics of course distortion is higher but so is the slam factor! :D

SET12 :smoke:

eico_hf81_schematic_full.jpg
 
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