I just bought three of them off eBay in non working condition. The seller didn't say what was wrong with them, and I'm not sure if he even tested them. I plugged one it for about 10 min and the output of one set of speaker terminals is 35 mv and the other is right around 1 mv. Would I be safe to hook it up to a preamp and a set of speakers?
They all look the same inside, it looks like someone was doing some mods.
Safe? Probably, but who knows.
i would just turn down the attenuators, hook up a crap speaker, touch the
input with my thumb, and turn up the attenuator expecting to hear 60Hz and
harmonics (buzz), which should go away when thumb is no longer applied.
A finger is as good as a thumb.
if you ground the same hand elsewhere on the input connector the buzz should lessen.
built in test signal that doesn't risk a pre
Do not use both hands.
If this works, try a preamp (still on crap speaker)
No buzz or hum, I'll have to buy some RCA-XLR adaptors tomorrow and hook them up to my preamp. Should I be concerned that the XLR connectors are reversed compared to a normal amp? From what I have read pin three is hot, and normally pin two is hot.
Concerned?Originally Posted by robertg
No, but be aware that the RCA-XLR adapters MUST be wired XLR pin 3 to RCA center pin or nothing passes through. If you can't open them to swap pins, don't buy them unless they are already wired the way you need. Use an ohmmeter to check...
Mike Scott in SJ, CA
Drive 'em to the Xmax!
My plans are to eventually run these amps with a M553 crossover which has pin two positive. So it looks like I have to make custom cables?
Aren't the JBL/UREI amps the same design 3XLR connections as the JBL/UREI M553 crossover??
Pretty sure when I ran the 6230 and 6260 amps with the M553 they worked fine ...
I didn't have to do custom cables until I got other hardware involved later, Like the Ashly crossover ...
2ch: WiiM Pro; Topping E30 II DAC; Oppo, Acurus RL-11, Acurus A200, JBL Dynamics Project - Offline: L212-TwinStack, VonSchweikert VR-4
7: TIVO, Oppo BDP103D, B&K, 2pr UREI 809A, TF600, JBL B460
Might have to DIY the RCA->XLR though.
I ended up buying RCA to 1/4" adaptors today, I hooked everything up and all three of them work fine. I'm not sure why the eBay seller said they weren't working, but I'm not going to complain.
I double checked both manuals, and the M553 crossover does have opposite polarity than the 6230, so I'm going to have to change that somehow. I can buy phase reversing XLR plugs on eBay for almost nothing, so I think I'm going to do that rather than making my own cables. At least for now.
The Hartsfields that I am building are almost done now, so hopefully I will have everything going in the next month. I'm still waiting for another 6290 amp that I bought off eBay.
Glad to hear it.
Project is coming along nicely!
So it looks like you can reverse the polarity on the M553 crossover by changing these jumpers. I'm assuming they do this to work with the old JBL amps with reverse polarity?
I picked up my 6290 yesterday, it weighs 63 pounds. The fan is a little loud, but I thought that I read somewhere that there is a mod to make it quiet?
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