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Luxman MB3045 with XLR input?

tutor_turtle

tutor_turtle

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My Luxman MB-3045 monoblock amplifiers are 16 feet (4 meters) from the preamp in order to have short speaker cable runs.
Single-ended RCA's are really not up to the task at that length, without spending an exorbitant amount of money.

My BAT preamp has XLR outputs as well as RCA

Has anyone converted their Luxman to differential input?
 
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I'd rather have long speaker wires than long interconnects.

Did experiments with the amps pushed up against the speakers so the speaker wires were 12 inches long.

No one was able to hear the difference between 15 foot speaker wire and 12 inch wires...

Balanced means there is extra circuitry to make the conversion, And that I can hear as a negative.
 
Disagree. I think 16ft is not at all too much for unbalanced unless maybe you live in a super high noise environment. That's less concern for me than the added circuitry of balanced to unbalanced conversion.
 
Its not really practical to modify one of these for balanced input. The front end is technically a diff pair input, but the "other" grid is being used for global feedback and without a lot of messing around it won't accept an inverting input from an XLR.

I suppose a BALUN is an option but then you're dealing with whatever the transformer or op amp adds to the mix.

tend to agree about just extending the speaker cables to allow for more reasonable RCA cables here. 16 feet just isn't that absurd of a length for either.
 
My preamp to amp cable is 25 feet, single ended. I did go to some length to purchase low capacitance cable. But there are no issues in my system with noise. Your mileage may vary.
 
tutor_turtle said:
My Luxman MB-3045 monoblock amplifiers are 16 feet (4 meters) from the preamp in order to have short speaker cable runs.
Single-ended RCA's are really not up to the task at that length, without spending an exorbitant amount of money.

My BAT preamp has XLR outputs as well as RCA

Has anyone converted their Luxman to differential input?
Click to expand...
I too would prefer longer speaker wire than pre to power amps. my set up i have about 4' RCA from pre to power amps and 12'-14' equal between power amp to speakers... yet im also pushing 40 common watts , instantaneous of 100 watts so the distance to speakers to me is not that much of a determent in sound quality.. speakers are 14' between them. zero noise or hum at 40 watts no music playing.
the only time i used XLR was from mike's to multi channel sound board for the band, XLR from sound board to multi track tape machine, RCA from tape machine to power amps Yamaha Natural Sound Power Amps, RCA from amps to speakers 40' wires, never had any problems, concerns or complaints 10-15 years. now im the last of the band and sold all my band equipment, 25 year ago.
 
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A tube linestage with double-digit output Z is pretty darned simple. Also easy to get *EXCELLENT performance from. Last one we measured 31 Ohms from 6AH4/6CK4 amplifier tubes and cascode MOSFET active loads. That number is well into 'drive anything' territory and able to ignore cable capacitance as long as the DCR of the cable is insignificant...

From the historical side, Kenwood applied the short speaker cable practice to the L-07 amp/pre family. IIRC that beast was listed at 10 Ohm output Z. Special RCA plugs with a screw connection on top of the push-in were employed and pre-to-amp patch cords were supplied with the linestage.

Douglas
 
was that the one that had the special speaker cables so the feedback came from the speaker end of the cables rather than the amplifier end?
 
The L-07M had two sets of multi-conductors per cable. A meter long with the multi-conductors connected at each end for attachment to the amp/speaker. They had not come up with the feedback, yet.

The sales booklet about the amp and preamp recommend short speaker wires, the 1-meter ones supplied and longer preamp to power amp cables with 25-foot ones supplied.
 
I have 25 ft single ended between my SS preamp and my 300b power amp, no issues at all.
 
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gadget73 said:
Its not really practical to modify one of these for balanced input. The front end is technically a diff pair input, but the "other" grid is being used for global feedback and without a lot of messing around it won't accept an inverting input from an XLR.

I suppose a BALUN is an option but then you're dealing with whatever the transformer or op amp adds to the mix.

tend to agree about just extending the speaker cables to allow for more reasonable RCA cables here. 16 feet just isn't that absurd of a length for either.
Click to expand...
The reality is the very small living space I find myself in:
Retired, small cottage, We built a beautiful cabinet to hold the amps and record collection, book-ended on each side by Klipsch Cornwal IV's, wood to match the speakers.
It really showcases the amplifiers.

Equipment rack (also hand built into an adjacent wall) holds: Preamp, CD, DAC/ADC, Tape Machines, 'Table, Phono pre-amp, Tuner, NAS drive storing audio/video files, cable modem, power conditioner, Bluesound, Ethernet hub, more records......
Leaving little room for two Luxman monoblocks and the air they require.

This cabinet is open-backed to the living room wall (another piece of custom cabinetry), allowing cable sharing and access with the: TV, Blu-ray, A/V receiver, left/right and center speakers, Apple TV....

Now, I could shuffle some records to the space the the amps occupy and put the amps closer to the preamp.
The (stupidly expensive) speakers cables I purchased before the move to my present tiny quarters, they might just make the run... If they make it, I'll give it a try.

Otherwise I'll have to research into highly shielded RCA's. I am picking up digital noise from the fiber optic network hub.
I raised it as far as the wires allow, it helped a lot, (so I know this is the culprit.) but didn't eliminate it.
The hub distributes the ethernet/WiFi traffic, which the audio streaming and audio capture requires.

I really like the look of the current setup. Any suggestions on studio quality RCA's? 16 feet (4m) would do the trick.
 
Are you certain the noise is coming in on the cables?

Personally, I'd look extra hard at relocating the network stuff if you're sure that's the source rather than crossed fingers betting on cables.
 
I was messing with stuff last night and hooked up an amp that had a fair amount of background noise. Figured out it was a ground loop, the DAC feeds from the computer which is grounded. The amp also has a ground. It wasn't the usual hum, it was a hiss that I thought was a bad tube or something. My very lazy fix was tape on the amps grounded cord to shut it up. It was just for testing so I wasn't going nuts trying to find a better solution

So maybe try shuffle things around just in case its a situation like that.
 
whoaru99 said:
Are you certain the noise is coming in on the cables?

Personally, I'd look extra hard at relocating the network stuff if you're sure that's the source rather than crossed fingers betting on cables.
Click to expand...
Moving the network equipment further away eliminated the noise. Good call.

However, in the diagnosis process, a friend brought over some (again stupid expensive) cables to test. Tellurium.
They are in the $100's per meter.
They helped tame some subtle sibilance issues I'd been hearing on certain recordings.

So while I've got to keep my amps front and center, (yay) I'm now on the hunt for better RCA's
I've had to re-terminate the ends with better jacks on the ones I have now.
The shield to ground connection would fracture if I moved the amp around (to roll tubes and subsequent re-bias)
They aren't high quality cables and really should be upgraded.
 
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