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Greg86z28
10-31-2015, 03:35 PM
So last night I finally got my 4345s up in the living room. I refoamed the 2122Hs and 2245Hs with Rick Cobb surrounds. All is well. To start out, I want to run my single JBL 6260 on the 2245s, and then my McIntosh 7270 on the top. (I plan on finding another 6260 so I can run one on each 2245). I think that can be a good starting point to build on.

However, I found last night that the connections on the 5234A external crossover are not simply RCA in, RCA out. There are two options, screw terminals or TRS plugs (phone plugs). I also read that the INPUT (Preamp to Crossover) should be a balanced connection, and then the OUTPUT (Crossovers to PowerAmps) should be unbalanced.

My thought is I should make some short jumpers ~6" that are male TRS plugs (phone plugs) to female RCA jacks. Is that the right idea? I would also need to take care to make sure I wire the connector correctly since this would need to be a balanced connection.

Note, all my cable runs in my system are fairly short (Speaker cable <10', interconnects <6')

What do you think?

Thank you

Greg

speakerdave
10-31-2015, 08:34 PM
My memory about these connections has become bit foggy. In your situation I would use the 7270 full range until I got the rest of it sorted out. I used interconnects with RCA's on one end and TRS on the other. Every additional connection potentially degrades the signal. The three-pin connections on that piece are nonstandard and on the amp also. The 5234A will improve the bass some, but there is a price to be paid in the treble. There's also a question of how to reproduce the phase inversion connection to the woofer vis a vis the bass/midrange. I'm not being much help here, I fear. I did not use my 5234A for very long, because I had the alternative of a Bryston 10B with which I could sort of emulated the asymmetrical slopes of the the woofer/midbass handoff in that speaker, and it sounded better to me. Somewhere deep in the bowels of this forum are some threads about all this. God, I miss the Z-man. Use Google for searches. Meanwhile enjoy the speakers with the internal crossover. They are fabulous bit of "kit."

Greg86z28
11-02-2015, 01:27 PM
My memory about these connections has become bit foggy. In your situation I would use the 7270 full range until I got the rest of it sorted out. I used interconnects with RCA's on one end and TRS on the other. Every additional connection potentially degrades the signal. The three-pin connections on that piece are nonstandard and on the amp also. The 5234A will improve the bass some, but there is a price to be paid in the treble. There's also a question of how to reproduce the phase inversion connection to the woofer vis a vis the bass/midrange. I'm not being much help here, I fear. I did not use my 5234A for very long, because I had the alternative of a Bryston 10B with which I could sort of emulated the asymmetrical slopes of the the woofer/midbass handoff in that speaker, and it sounded better to me. Somewhere deep in the bowels of this forum are some threads about all this. God, I miss the Z-man. Use Google for searches. Meanwhile enjoy the speakers with the internal crossover. They are fabulous bit of "kit."

Thanks.

Right now I am just using them with the internal crossover and my 7270.

Ian Mackenzie
11-07-2015, 09:30 AM
Hi Greg,

To obtain the full potential of the 4345 it needs bi amping.

The bass will sound woolly in full passive mode.

I am not sure if the passive crossover is stock but the overall system transparency can be can be noticeably improved by updating the crossover to charge coupled . Search the forums for this.

The vintage 5234A can be used but needs to be used with the customised crossover card for the 4345 that has 18 db 3rd order slopes at 290 hertz.

You can use a unbalanced input by earthing the negative input connection while using the positive input to the centre wire in the RCA lead and the negative input to the shield.

The output negative should not be earthed.

This would get you going but is the entry lead to bi amping.

The 5234A is an old design with old parts and it will not be as transparent as current day active crossovers like the Bryston or the Pass Labs First Watt B4.

Greg86z28
11-08-2015, 05:34 PM
Thanks Ian.

I think moving forward, the best route is to hook up the external crossover, since I have the cards already. Then, in time, I can start to upgrade.

That being said, the only thing I need to do is create my jumpers. I have to decide between using the TS/TRS or spade connector. Which would be easier/cheaper/better?

Thanks!

Greg




Hi Greg,

To obtain the full potential of the 4345 it needs bi amping.

The bass will sound woolly in full passive mode.

I am not sure if the passive crossover is stock but the overall system transparency can be can be noticeably improved by updating the crossover to charge coupled . Search the forums for this.

The vintage 5234A can be used but needs to be used with the customised crossover card for the 4345 that has 18 db 3rd order slopes at 290 hertz.

You can use a unbalanced input by earthing the negative input connection while using the positive input to the centre wire in the RCA lead and the negative input to the shield.

The output negative should not be earthed.

This would get you going but is the entry lead to bi amping.

The 5234A is an old design with old parts and it will not be as transparent as current day active crossovers like the Bryston or the Pass Labs First Watt B4.

JeffW
11-08-2015, 05:47 PM
Hard to be any cheaper than a spade - you don't even need a spade, just wrap the wire around the screw.

Greg86z28
11-08-2015, 06:12 PM
Hard to be any cheaper than a spade - you don't even need a spade, just wrap the wire around the screw.

I need to connect an RCA cable to a spade or TRS connection . I'm going to make a male spade (or TRS) to female RCA connection cable.

pyonc
11-12-2015, 07:54 AM
So last night I finally got my 4345s up in the living room. I refoamed the 2122Hs and 2245Hs with Rick Cobb surrounds. All is well. To start out, I want to run my single JBL 6260 on the 2245s, and then my McIntosh 7270 on the top. (I plan on finding another 6260 so I can run one on each 2245). I think that can be a good starting point to build on.

However, I found last night that the connections on the 5234A external crossover are not simply RCA in, RCA out. There are two options, screw terminals or TRS plugs (phone plugs). I also read that the INPUT (Preamp to Crossover) should be a balanced connection, and then the OUTPUT (Crossovers to PowerAmps) should be unbalanced.

My thought is I should make some short jumpers ~6" that are male TRS plugs (phone plugs) to female RCA jacks. Is that the right idea? I would also need to take care to make sure I wire the connector correctly since this would need to be a balanced connection.

Note, all my cable runs in my system are fairly short (Speaker cable <10', interconnects <6')

What do you think?

Thank you

Greg

Hi,

I believe 5234A is an excellent crossover, though it's an old design. You can easily find the right input phono jacks (1/4 TRS) from Aamzon. I currently use one fitted with facotory 4343 lo cards for my speakers(JBL 4343) in biamped mode, with excellent outcomes. The beauty of this vintage crossover, when fitted with the right factory spec cards, is the full reproduction of the authentic sonority of your speakers. I've both used JBL M552 and Ashly XR1001, and personally find 5234 one cut above, due to its correct LF cut. By the way, 4343 and 4345 share the same network to the best of my knowledge.

Greg86z28
11-12-2015, 03:22 PM
Sorry to ask such basic questions, but can you guys help me get the right stuff? What exactly should I purchase?

So to make a single connector, say the left channel (going from left channel out of the preamp, to left channel in of the crossover), I will need a standard spade connector, a standard female RCA connector and then speaker wire? The red wire will go from the "tip" of the RCA connector to the spade, and then the black wire would be from the shield to ground?

Thanks for hanging in there with me.

Greg

JeffW
11-12-2015, 03:43 PM
Aren't the female RCAs generally on the equipment? Seems to me you'd want male RCA<--->spade cables. Other than that, your connection choice sound fine to me.

And there are commercially available RCA to spade and RCA to TS cables and connectors. I think TS would be simpler, you could just buy these and use regular RCA cables

http://www.amazon.com/gp/product/B01045YYCK/ref=pd_lpo_sbs_dp_ss_2?pf_rd_p=1944687702&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000068O3V&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=12CXW7YF39FWYKG4JF4R

BMWCCA
11-12-2015, 04:42 PM
Sorry to ask such basic questions, but can you guys help me get the right stuff? What exactly should I purchase?

I'm going in circles trying to follow this. Would it be too much to ask for you to post some photos of the jacks to which you're trying to make connections? I think that would certainly help.

:spin:

speakerdave
11-12-2015, 05:16 PM
Here's a link to the manual for the 5234A. Maybe that will be helpful.

http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/JBL-5234A%20manual.pdf

Greg86z28
11-13-2015, 03:44 PM
Ok let's start from the top. Thanks again for bearing with me. Here is what I want to do:
https://lh3.googleusercontent.com/-OIEz09_T8RY/VkZkH_-zB0I/AAAAAAAAGJg/mtUs_mBV2NQ/s800-Ic42/Layout.jpg

I'm basically stuck on what wires to use (where the question marks are). The 5234A doesn't have RCA ins/outs. It has spades and phones (see next 3 pictures).

https://lh3.googleusercontent.com/-Of2SEVD4yg0/VkZi7JoLMzI/AAAAAAAAGJI/a_cx-d94Uss/s800-Ic42/IMG_2077.JPG

https://lh3.googleusercontent.com/-fJ5KvSoO_dA/VkZjR6FBEaI/AAAAAAAAGJY/GX5UDwzWBDo/s800-Ic42/IMG_2078.JPG

https://lh3.googleusercontent.com/-RKjiaEuD094/VkZjK2paHyI/AAAAAAAAGJQ/gZoqALKVKYk/s800-Ic42/IMG_2079.JPG



The two cables coming out of my preamp are a L and R RCA (Audioquest Evergreens). My understanding is this would be a "unbalanced" connection. Is that true? I think from reading the 5234A manual, I want to convert this to a "balanced" connection.

How do I create a female RCA to spade (or phone plug) balanced jumper?

For the outputs, the 5234A has unbalanced outputs, so I think I just need to create a spade (or phone plug) to female RCA unbalanced jumper. This would then hook up to each power amp.

Thanks!

Greg86z28
11-13-2015, 03:59 PM
This is my best guess on a "balanced" connector (RCA Female to Male TRS).

https://lh3.googleusercontent.com/-WTMSEasFomk/VkZrEzad9rI/AAAAAAAAGJw/cupw3SKkeo8/s800-Ic42/Balanced%252520Connector.jpg

JeffW
11-13-2015, 04:06 PM
You can't make a balanced connection from unbalanced. You can connect between the two, generally, but the actual circuits on both ends need to be balanced for balanced connections to work. Your second sketch is what I linked to in post #10, but it won't be balanced. A balanced connection needs three conductors, and circuitry on either end that supports it. The reason I repeat that point is that some gear could have XLR connectors yet still not actually be balanced, and even if it was, you'd lose the "balanced" part as soon as it was connected to an unbalanced piece of gear.

BMWCCA
11-13-2015, 06:13 PM
I agree that if you're not balanced from start to finish, then you're not balanced so no need to worry about it. Just connect your pre-amp output to the 1/4-inch inputs either with 1/4-inch adapters to standard RCA cables or readily available cables with RCA phono males on one end and 1/4-inch males on the other. I have 4345s and bi-amp them using an Ashly crossover and that's what I do. Now my Crown amps take 1/4-inch inputs so that's a bit easier as I just use 1/4-inch males on both ends of the cable from the crossover to the amps. Here's what I use when I have to go RCA to 1/4-inch and they've worked well for me with Crown amps for years in non-bi-amp systems:

Greg86z28
11-14-2015, 06:13 AM
Wow, thanks a bunch guys.

I did miss the part about not being able to take an unbalanced connection to a balanced connection. My mistake.

However, I think I feel comfortable getting the items I need. Will let you guys know when I get them hooked up.

Greg

grumpy
11-14-2015, 09:43 AM
If you can find, or are willing to make up a set of RCA to spade cables,
I think you'd have fewer "bad connection" problems. Personal preference
and a bit of experience with old 1/4" phone jacks.