How do I biamp my 4333A?

[mesudman]

Hi guys

I have a 4333A speakers with original network and 5235 crossover with cards build for them by Guido.

I do not know how to biamp them and what other parts I need to do that.

I understand that I have to remove the original network and build CC networks.

Please advise.

Thanks a lot,

Regards,

Alex

[martin2395]

Alex,

You don't have to change the original networks at all! The CC networks sound better but they aren't necessary for bi-amping.

Your 4333A should have a switch on the back, just under the speaker connectors saying "INTERNAL CROSSOVER / EXTERNAL CROSSOVER". For biamping make sure it's set to external.

Then it goes like this:

Preamp/Mixer -> Urei 5235 Low output -> amplifier no.1 -> low frequency terminals
.......................Urei 5235 Hi output -> amplifier no.2 -> high frequency terminals


On this picture you can see the bi-amp switch:
62502

Also a small advice - The urei 5235 has XLR connectors in reversed polarity (pin 3 hot = signal is out of phase) you might want to change it to 'modern' standard.

[speakerdave]

Biamping the 4333A is comparable to biamping the 4345, 4350, 4355 and other large format JBL monitors with biamp switches installed. With the 4333A as with the others in bi amp mode the low pass network elements are taken out of the circuit (except for the zobel in the case of the 4333A). It is the primary point of biamping to get the large inductor of the low pass out of the signal path between the amplifier and the woofer.

The high pass part of the internal networks shapes the signal to compensate for response anomalies in the drivers, besides dividing frequencies, so unless one is able to provide external equalization the internal high pass section is needed to make the speaker sound the way the system engineer designed it to sound. With the other monitors the external crossover must provide the high pass for the midbass cone, but the high pass of the internal 4333A crossover, though altered by the biamp switch, stays in the circuit, with its necessary response shaping. This was probably done to protect the midrange compression driver from user error.

Use your external crossover between the preamp and power amp for the low frequencies only. Drive the high frequency power amp directly from the preamp. As far as I know there is no dedicated card for the 4333A as there is for the other monitors mentioned, and it is not necessary. The 52-123 card recommended by the JBL 4333A literature is a generic 12dB 800Hz frequency divider. Although not mentioned in the literature the manual for the speaker would probably make it clear that the high pass section should not be used. You don't need the high pass part of it for the 4333A, and if you use it, it won't sound right, and you will unnecessarily be adding a layer of electronic circuitry into the high frequency reproduction chain where it is most audible.

That's a very fine speaker, by the way. I enjoyed mine a great deal during the years I had them. Here's the schematic:

[mesudman]

Thanks a lot guys !

Now my question is : Do I need two identical amplifiers or not ? I have a B&K M200 sonata with Electrocompaniet EC-1 preamplifier and the second one Mcintosh MC2505 its on his way !

Let me know what your opinions are ..

Regards,

Alex

[speakerdave]

You really don't have a lot of choice, since the 2505 is inadequate for the woofers. It is a very nice little amp however, and although there will be people who will poopoo it for the horns you will find that it is actually perfectly fine for that. I know, because I've done it. You're going to like it. I would use the 8 ohm taps.

[mesudman]

I was wrong. I meant the Mcintosh Mc 2205 . The one with 200 wpc .

Thanks

regards,

Alex

[martin2395]

Personally I wouldn't use a McIntosh to drive the bass. I always found them to sound too "spongy" due to very low DF factor.

Crown gear like the K2 or older BGW or even Bryston work wonders on the bass;)

[bldozier]

Could you bi amp with the internal crossover

[bldozier]

Biamping the 4333A is comparable to biamping the 4345, 4350, 4355 and other large format JBL monitors with biamp switches installed. With the 4333A as with the others in bi amp mode the low pass network elements are taken out of the circuit (except for the zobel in the case of the 4333A). It is the primary point of biamping to get the large inductor of the low pass out of the signal path between the amplifier and the woofer.

The high pass part of the internal networks shapes the signal to compensate for response anomalies in the drivers, besides dividing frequencies, so unless one is able to provide external equalization the internal high pass section is needed to make the speaker sound the way the system engineer designed it to sound. With the other monitors the external crossover must provide the high pass for the midbass cone, but the high pass of the internal 4333A crossover, though altered by the biamp switch, stays in the circuit, with its necessary response shaping. This was probably done to protect the midrange compression driver from user error.

Use your external crossover between the preamp and power amp for the low frequencies only. Drive the high frequency power amp directly from the preamp. As far as I know there is no dedicated card for the 4333A as there is for the other monitors mentioned, and it is not necessary. The 52-123 card recommended by the JBL 4333A literature is a generic 12dB 800Hz frequency divider. Although not mentioned in the literature the manual for the speaker would probably make it clear that the high pass section should not be used. You don't need the high pass part of it for the 4333A, and if you use it, it won't sound right, and you will unnecessarily be adding a layer of electronic circuitry into the high frequency reproduction chain where it is most audible.

That's a very fine speaker, by the way. I enjoyed mine a great deal during the years I had them. Here's the schematic:
That is horizontal bi amping not vertical