Carverfest Tube Amp upgrades Please post ideas.

I think the point to consider is that you can use RCA to XLR cables and have the same result- no need to put XLR connectors on the amp.

Ed Zachary.

I think the point to consider is that you can use RCA to XLR cables and have the same result- no need to put XLR connectors on the amp.

Balanced to unbalanced (& vice versa) can be problematic. There have been multiple threads on this:

viewtopic.php?f=37&t=6789&p=73200&hilit=xlr+balanced+unbalanced+rca#p73200

viewtopic.php?f=8&t=3431&p=25135&hilit=xlr+balanced+unbalanced+adapter#p25135

viewtopic.php?f=37&t=11965&p=115916&hilit=xlr+balanced+unbalanced+rca#p115916

viewtopic.php?f=17&t=13274&p=131276&hilit=xlr+balanced+unbalanced+rca#p131276

viewtopic.php?f=39&t=5694&p=56657&hilit=xlr+balanced+unbalanced+opamps#p56657

Simply using a converter jack or balanced on one end & XLR on the other is not really a solution. Balanced lines run @ 10dB down from RCA, but when summed back together at the end, they have the same output. When you use an adapter, you lose half that summing & get a much reduced output level. It can also introduce noise/hum/ground loop issues.

XLR/TRS balanced cables make everything a LOT more complicated & are only really necessary when you have long runs or issues with noise picked up by cabling.

Balanced lines run @ 10dB down from RCA, but when summed back together at the end, they have the same output. When you use an adapter, you lose half that summing & get a much reduced output level.

Ah, I did not know this. Thanks.

All depends upon the cable quality- no? If you do not let noise in- it was there to begin with...

http://www.amazon.com/Mogami-Gold-XLRM-RCA-06/dp/B001LNN2GE

All depends upon the cable quality- no? If you do not let noise in- it was there to begin with...

http://www.amazon.com/Mogami-Gold-XLRM-RCA-06/dp/B001LNN2GE

The quality of the cable CAN deter SOME outside noise interference, but certain noises will override ANY unbalanced cable (fluorescent lights & those slider fan & light potentiometers introduce TONS of noise).

Incidentally, the cable you referenced is a compromise, as stated in some of the threads I posted above. It's basically taking one half the 2 unbalanced signals & running it to the RCA. You get greatly reduced output that way.

I could write a book about right here on this topic but don't have time.

Balanced versus unbalanced can have three big differences. Impedances, level and grounding...along with the wiring.

Balanced means the same signal is run inverted in phase on a second line. That means when one side is going up in amplitude, the opposite phase is going down equally. Equal amplitude going in opposite direction means double the voltage (compared to unbal) over any noise...BIG advantage. Also means 6db more signal, stated differently. Nothing automatically means it can't also be a -10db signal. It's just a loose standard in audio that balanced is run at +4. The voltage on the line between -10 and in a balanced +4 is much larger than looking at those two numbers makes it seem.

Interfacing balanced driving unbalanced...versus unbalanced driving balanced has different issues and it gets glossed over all the time. Buying an adapter without understanding the issues than can arise, including damage is common! The main thing to remember is to NOT short any driven output (unless it's a "servo" balanced one). Unbalanced driving a balanced input has less dire possible results. The adapters can get you there normally. Balanced outputs going to a unbalanced input require more care to get right when you're not familiar with all the tricks and pitfalls.

A high quality (expensive) transformer is still the best way to interface. The mention I saw of the Rane transformer having a noise issue suggests miswiring as they are pretty good ones in those. Like many things in audio, the transformers that are good were largely done away with due to expense, size and weight and when they're quality, they exceed in use the theorical numbers of op-amps...this is contrary to convential thinking of today. I've never heard an active matching box that didn't hurt quality much more than I'm willing to accept.

Gary, if one device was wired with a different pin as high, that makes no real difference as long as L and R are wired the same way. All it does is flip absolute phase which has about as much chance of winding up being right as wrong. That's referring to the "Wood Effect". Absolute phase is irrelevant with most modern music...except the type of stuff I put on the CF disc for the most part!

Broadcast standard in the field was at one time pin 3 high and what I call semi-pro audio used pin 2 high. More correctly I think, Europe used pin 2 and eventually that became more typical. So devices that are around with pin 3 high are just stupid people...it's just they were using a "different standard". Means little in my field except always looking at the manual for the gear when wiring it.

Mark

Buy 'em here hand made as to what you need - http://www.bluejeanscable.com/store/balancedaudio/index.htm
In addition to the Neutrik XLR connectors, we also carry 1/4 inch TRS Phone Plugs from Canare; these are intended for use where balanced lines are run in a TRS configuration--not, of course, where the 1/4 inch TRS plug is being used for stereo unbalanced audio. Additionally, we do carry Canare solder-type RCA plugs which can be attached to these cables to make a balanced-to-unbalanced connection; however, since there's no single accepted standard for wiring an XLR-to-RCA cable, we ask that you write to us and let us know what pinout you need before ordering such a cable.

On the porch I run short 6' balanced from my BenchMark Pre amp to the amp so I can use the RCA outs to run to my sub. Rabbit told me way back when not to buy the "Frankenstein" mix above -

Point is......IF you come out of the pre with an RCA and go to XLR on the other end it DOES NOT MATTER! It is still the same signal. I agree with Mark for going the other direction- a transformer would provide isolation for impedance swings-

Mark knows what he is talking about- I have no doubt there!

The problem will be that the line receiver will just about halve the input signal.

It would still be the equal to an RCA signal- It would only matter if you need that kind of gain or have a very long run (isn't that what XLR is intended for?). My system does just fine with RCA's- but some do like it ear bleedin LOUD

It would be the same signal.

Thanks BillD- that is what I was thinking.

this is a mono/stereo switch
no need for Y cables and the jumper between the Pos. speaker leads





got the word from a good source that some of the hum issues may be from the power transformer coil and OPT being all in the same line, N\S. poles. the one closest to the PS.
so I whipped up these little fellas, this will put the OPT at 90deg and 90deg flat to the PT, this should help











stock cover will fit also....

this is a mono/stereo switch
no need for Y cables and the jumper between the Pos. speaker leads

got the word from a good source that some of the hum issues may be from the power transformer coil and OPT being all in the same line, N\S. poles. the one closest to the PS.
so I whipped up these little fellas, this will put the OPT at 90deg and 90deg flat to the PT, this should help.

stock cover will fit also....

Nice work on that bracket Mike!

The new Bob Carver LLC 20/20 amp will also have that stereo-monoblock switch, I'm glad to see someone else tried it!