Amplifier and Crossover questions for JBL 4435

[Valveglow]

Hello all. Though I have done searches on this topic and consulted members of other forums on this topic, it seems as though my search for info should have begun here. If not, I am inclined to think it my issues will be resolved here. Thank you in advance.

I have purchased a pair of JBL 4435s, though I am not certain which version. I believe they were built in the late 80's, though again, I am not 100% sure of this. Jazz, mostly "Miles Davis-ish" (whatever that means) is what I spend most of my time listening to, though I also enjoy lots of other jazz, fusion, vocals, classic rock and Prog Rock as well. Generally, I listen at low to moderate volumes and rarely crank it up. Having purchased 4435s though, I do not want to forfeit that ability when the mood strikes me!

My concerns involve amplification and crossovers. I would like to use a set of VTL 225 Watt Triode Mono Blocks to power them, though I am also considering a Crown XTI amp (either a model 1000, 2000, or 4000) with plenty of steam to power the woofers. I also own VTL 100 watt mono blocks, so I could also use both sets of the tube amps. The issues are as follows:

• Since the Crossover frequency is factory set at a critical 1Khz, I am concerned with the solid state amp possibly diminishing the wonderful presentation that a big tube amp can deliver smack in the middle of the midrange.
• Some have said that utilizing the internal crossover is a great idea (though I do not have the internal cards that were available for these speakers) even if I run both amps.
• I also have a JBL M552 Crossover, which I have heard would be superior to the internal crossover, though I have also heard the exact opposite!

Would you folks think that one tube amp would be sufficient? What about both sets of tube amps? Tubes on top and solid state (in the lower middle) and bottom? I'm sure that some of you would recommend two solid state amps. Regarding the crossover issue also, I greatly appreciate both individual and collective wisdom on your part. Thank you again!

[audiomagnate]

I would go with electronic crossovers and tubes on the top. Just change one at a time and see which setup you like best.

[Ian Mackenzie]

I would not waste those VTL amps on them imho.

However, I suggest try the 4 ohm tap on the mono blocks and how they perform.

If you play jazz then its the first watt that matters.

I would caution using the M552 initially in biamp mode as it will wash the sound with a hardened glare that will be painfully obvious using the VTLs. (Assuming you can afford the VTLs get a Passlabs XVR1 crossover from Renohifi and ask Kent English at Pass labs for advice on set up for the 4435s.)

The icing on cake is retro fitting Tad 2002 Be drivers to these bi radial systems.

You will then have it

[Valveglow]

Oh, Oh! I'm a bit scared now! I simply cannot wait to play these 4435s. Are they that unimpressive/colored/2 dimensional/etc. that my tube amps would be a waste on them? I felt that if they did exhibit a hardness that the tubes would do much to "relax" the presentation, though the VTLs are not really soft sounding like a '60s tube amp.

The 4 Ohm tap makes sense to try, although would the impedance be closed to 8 or 4 for these speakers? What about for just the cheeks alone? Woofers alone? The JBL spec only says that the (total system) impedance is 8 and generally greater than 4 ohms.

I was a bit afraid of the M552 for the reason you identified. Is it possible to just run 2 different amps directly into the speakers' 2 taps, utilizing the internal crossover alone?

Thank you VERY much!

I would not waste those VTL amps on them imho.

However, I suggest try the 4 ohm tap on the mono blocks and how they perform.

If you play jazz then its the first watt that matters.

I would caution using the M552 initially in biamp mode as it will wash the sound with a hardened glare that will be painfully obvious using the VTLs. (Assuming you can afford the VTLs get a Passlabs XVR1 crossover from Renohifi and ask Kent English at Pass labs for advice on set up for the 4435s.)

The icing on cake is retro fitting Tad 2002 Be drivers to these bi radial systems.

You will then have it

[Valveglow]

More sensible advice which I greatly appreciate. I am wondering though if I can use the 2 amps DIRECTLY into the 2 taps WITHOUT any external crossover. Thank you.

I would go with electronic crossovers and tubes on the top. Just change one at a time and see which setup you like best.

[audiomagnate]

More sensible advice which I greatly appreciate. I am wondering though if I can use the 2 amps DIRECTLY into the 2 taps WITHOUT any external crossover. Thank you.

You have high and low inputs on your 4435's? I'm not seeing that on the schematic: http://www.jblproservice.com/pdf/Stu...ries/4435LR.pd

[allen mueller]

You need an external crossover to bi amp the 4435. The crossover slope for bi amping them is asymmetric so you either have to track down an old jbl crossover with the proper cards or get a dsp and replicate the slope of the crossover intended for biamping them.

This old thread explains it well:
http://www.audioheritage.org/vbullet...hlight=52-5130

Having 4435's my self and having done it both ways i wouldn't get stressed about going to bi amp right away. It is an improvement however you'll do just fine with some good amplification and the stock crossovers.

Allen

[Ian Mackenzie]

4 ohm tap, the system is 4 ohm passive.

My expectation is you will post a big Grin

[Fort Knox]

Oh, Oh! I'm a bit scared now!

Thank you VERY much!

I would use passive x-over for max sig/noise ratio
and tubes for best color..

[Valveglow]

Thank you. Due to the high efficiency of the 4435s and the fact that I almost always listen at low to moderate levels, I thought that I'd have tons of power with my 225 Watt Triode Mono Blocks. However, having seen JBLs specs regarding recommended amplifier power, especially when biamped, 225 WPC seemed woefully inadequate. I'm (fairly) sure it's plenty for me though.

Conversely, I do have a choice of 3 Crown XTI amps to use for the bottom, rated at 275/500, 475/800, 650/1200 WPC into 8/4 Ohms respectively. These amps have a DSP which permits selection of XOVER frequencies, slopes, pre-mapped curves, EQ, etc., which I would have liked to hear as well. I have heard on this site (and elsewhere) that my M552 JBL external XOVER is really not the way to go. Finding the original cards ($$$) seems prohibitive and difficult these days. Going the "better, aftermarket" XOVER route is not really an option as these speakers initial cost plus shipping(!) was already a substantial hit.

You need an external crossover to bi amp the 4435. The crossover slope for bi amping them is asymmetric so you either have to track down an old jbl crossover with the proper cards or get a dsp and replicate the slope of the crossover intended for biamping them.

This old thread explains it well:
http://www.audioheritage.org/vbullet...hlight=52-5130

Having 4435's my self and having done it both ways i wouldn't get stressed about going to bi amp right away. It is an improvement however you'll do just fine with some good amplification and the stock crossovers.

Allen

[Valveglow]

There are no dedicated 4 Ohm taps on my MB 225 amps, just a positive and negative for 4-16 ohms.

My first try will be with the MB 225s, and I do anticipate the big grin you mentioned. I may wind up selling the M552 XOVER unless I hear compelling arguments why it should be employed in the system. Nevertheless, my thoughts regarding the big Crown amp was really the woofer damping factor and not the maximun SPL.

I would not waste those VTL amps on them imho.

However, I suggest try the 4 ohm tap on the mono blocks and how they perform.

If you play jazz then its the first watt that matters.

I would caution using the M552 initially in biamp mode as it will wash the sound with a hardened glare that will be painfully obvious using the VTLs. (Assuming you can afford the VTLs get a Passlabs XVR1 crossover from Renohifi and ask Kent English at Pass labs for advice on set up for the 4435s.)

The icing on cake is retro fitting Tad 2002 Be drivers to these bi radial systems.

You will then have it

4 ohm tap, the system is 4 ohm passive.

My expectation is you will post a big Grin

[audiomagnate]

Thank you. Due to the high efficiency of the 4435s and the fact that I almost always listen at low to moderate levels, I thought that I'd have tons of power with my 225 Watt Triode Mono Blocks. However, having seen JBLs specs regarding recommended amplifier power, especially when biamped, 225 WPC seemed woefully inadequate. I'm (fairly) sure it's plenty for me though.

Conversely, I do have a choice of 3 Crown XTI amps to use for the bottom, rated at 275/500, 475/800, 650/1200 WPC into 8/4 Ohms respectively. These amps have a DSP which permits selection of XOVER frequencies, slopes, pre-mapped curves, EQ, etc., which I would have liked to hear as well. I have heard on this site (and elsewhere) that my M552 JBL external XOVER is really not the way to go. Finding the original cards ($$$) seems prohibitive and difficult these days. Going the "better, aftermarket" XOVER route is not really an option as these speakers initial cost plus shipping(!) was already a substantial hit.

Aftermarket crossovers are cheap. The Behringer DCX 2496 goes for around $300 and sounds great. I have 225 wpc (Nak PA-7) on my similarly drivered but 3 dB less sensitive L300s, and the clipping lights have never even flickered, and sometimes I listen loud. VERY loud. When you are listening at your "low to moderate levels," you are using way under one watt.

Are there high and low inputs on a 4435? The schematic doesn't show them and I can't find a pic of the input terminals.

FWIW, I had my L300's triamped for around a month, and have now gone back to one amp (with subs of course) and am quite happy. I did upgrade the caps in the tweeter circuit to Clarity ESA's, one speaker at a time, and couldn't hear a difference.

[Valveglow]

Thank you. Actually, I have the JBL M552 Crossover as well as a DBX 234 in another system that is really not needed. The trouble is that most folks I have spoken to say that these type (lower priced, active) XOVERS add a hardness to the sound, which I want to avoid at all costs. I find that I can hear a very slight ground hum type noise when the DBX is in circuit, which might be eliminated with grounding, cheater plugs, etc. Nevertheless, it moves one another step away from the "straight wire with gain" theory.

Regarding the picture of the input terminals, I had it somewhere, but cannot locate it, even searching online. Below is a similar unit, but NOT the one for the 4435s:

https://encrypted-tbn3.gstatic.com/i...3wgYiIyZeIezRQ

If someone could supply the correct photo, it would be much appreciated.

Aftermarket crossovers are cheap. The Behringer DCX 2496 goes for around $300 and sounds great. I have 225 wpc (Nak PA-7) on my similarly drivered but 3 dB less sensitive L300s, and the clipping lights have never even flickered, and sometimes I listen loud. VERY loud. When you are listening at your "low to moderate levels," you are using way under one watt.

Are there high and low inputs on a 4435? The schematic doesn't show them and I can't find a pic of the input terminals.

FWIW, I had my L300's triamped for around a month, and have now gone back to one amp (with subs of course) and am quite happy. I did upgrade the caps in the tweeter circuit to Clarity ESA's, one speaker at a time, and couldn't hear a difference.

[hjames]

Thank you. Actually, I have the JBL M552 Crossover as well as a DBX 234 in another system that is really not needed. The trouble is that most folks I have spoken to say that these type (lower priced, active) XOVERS add a hardness to the sound, which I want to avoid at all costs. I find that I can hear a very slight ground hum type noise when the DBX is in circuit, which might be eliminated with grounding, cheater plugs, etc. Nevertheless, it moves one another step away from the "straight wire with gain" theory.

Regarding the picture of the input terminals, I had it somewhere, but cannot locate it, even searching online. Below is a similar unit, but NOT the one for the 4435s:

https://encrypted-tbn3.gstatic.com/i...3wgYiIyZeIezRQ

Well, THAT image posting didn't do so well ...

[Valveglow]

Hello hjames! How are you? You always seem to come to the rescue when I am in "JBL trouble", no matter where I am! This image seems bigger, but it is still not the correct 4435 input terminals. SOMEWHERE, I did have the correct photo!

http://www.audioheritage.org/vbullet...1&d=1182674251

Well, THAT image posting didn't do so well ...