The standard for US equipment is pin 2 hot. Europe and most japanese brands use pin 3 as hot. It really doesn't do anything but reverse phase if it is not same, as Al stated. |
Sounds like you need a single ended to balanced transformer like the Jensen model. |
Yes, I suppose any circuitry added will have a sonic signature but the Jensen transformers are the same one's Audio Research and Rowland use to make their products balanced. They claim the sound is better than truly balanced but I don't know. It's certainly much cheaper at around 200.00.
Atmasphere, isn't losing 6db of gain the same as losing half the output of the amp or more? |
Al.
But because the amps are mono, they were probably converted from stereo by inverting the left or right channels thus making the amps differentialy balanced and increasing the power by a factor of four. By using only the positve half of the signal, you are losing the much of the power the amp would be capable of. |
Thanks Al. The reason I suspect the amps are converted from a stereo design is because the tech sort of alludes to the theory. There's many high end mono amps out there that are done the same. I look back at Audio Research's Classic 60 and Classic 120s as an example. I'm not sure but I suspect the 60s were converted in a like manner. Krell's KSA 300 can be converted to mono in a similar fashion. |
Al, if truly balanced is achieved best with mirror imaged circuits, what better way is there than taking a stereo amp and letting one channel drive the positive signal and the other drive the negative? I know this seems like a simplistic approach but it should work maybe at the cost of low impedence drive. |
It should be fairly easy to try anyway if he's still here. |
Al, thanks again for your answer and I see your point. But a stereo amp should also be closely matched as well. I am certainly no expert which is obvious. But an example of such an animal is MBL whom offers some of their most costly designs as either stereo single or a mono pair that simply uses the XLR input to make them balanced mono only. Such a design cannot be used in single ended mode as a mono amp. It could be used as a single channel amp in single ended mode but only with one channel which would be half as much power or less.
http://www.mbl-germany.de/Reference_html/9007.html |
Al the reason they don't offer balanced inputs for stereo is because they are using the two separate channels combined to make the amp balanced. One channel drives the positive and the other the negative. In stereo mode they wouldn't be able to drive the pos/neg legs of the balanced signal and keep a true differential balanced config. That's the reason you probably should not use an RCA adapter to convert an amp to single ended in this type of design. A friend had an ARC amp that only had balanced ins and was warned by a tech at ARC not to use an adapter on his amp. Balanced and bridged are closely related it appears. |
Sounds like you need a single ended to balanced transformer like the Jensen model.
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I still think that there will be a loss of power if the Palladium amps are using a
bridged balanced scheme which I suspect. From what I've read the Palladiums
are based on either the 4004 or 8008 stereo amps depending on vintage. |
I agree Atmo. I value your opinion and would like to ask what you think of a plan I have. I have a Citaion II that has been almost completely updated. It sounds great but would benefit from more power. I would like to find another and convert them to balanced mono by using the two separate channels of each amp for the positive and negative. Do you see any problems with this plan? Simply converting to mono is easy but I feel balanced would be better. |
One channel of the amp will be the positive input the other the negative of the XLR. This will bridge the amp but it will be balanced bridged operation. This is what the Pallidiums and MBLs are I believe. It is a pretty common. One of the outputs to the speakers will be the positve and the other positive output will be the negative or ground. Just like with a bridged stereo amp. |
This is from the Citation II manual and Jim Mcshane's site.
((Connecting Citation Amps In Mono (Bridged) Mode
Here's the how-to, right from the original H-K manual:
In order to operate the Citation II as a 120 watt monophonic amplifier it is necessary to fulfill two requirements:
1. The speaker output terminals must be strapped together. Tie the two ground terminals in parallel and then tie either the
two 8 or 16 ohm terminals in parallel depending on the nominal impedance of your speaker. For example, if you are using
an 8 ohm speaker, tie the two 16 ohm terminals together and attach the speaker between either 16 ohm terminal and
ground. If you are using a 16 ohm speaker it is permissible to connect it as described for an 8 ohm speaker, as a
mismatch of as high as 50% will not affect the tone quality.
2. The amplifier input terminals must be tied together if no preamplifier is to be used and the signal is being fed directly
by a tuner. If a monophonic preamplifier is used it is also necessary to tie the inputs together. This can be accomplished in
any of several ways. One method would be to use two patch cords with RCA type phono plugs on one end. The other
end of these patch cords would be tied together in parallel and soldered to another RCA type phono plug. Connect the
two individual RCA plugs to the input receptacles of the amplifier and the other end (which is paralleled) to the output of
your tuner. A more satisfactory method is to purchase a LAB-TRONICS patching plug, Part #A-7 54 to parallel the
inputs of the amplifier. This device would eliminate the need of soldering and would insure perfect connections.
3. If a stereo preamplifier is used input strapping is not required. Merely connect the two outputs of your preamplifier to
the corresponding inputs of the Citation II and connect the speakers as previously discussed.))
Yes, I would install an XLR for the inputs. I think noise rejection would be excellent. This should be the same as any other differentialy balanced amp which is what I should have. I also think the amp should have more than double the power this way. If anyone elso wants to weigh in you are welcome. Sorry to hijack the post though. |
I know Al, if it were that easy I wouldn't be asking. The amp is 50 years old. I don't suppose they had much balanced audio equipment then. I hope to get more power and noise rejection by doing it in a balanced configuration. |
I have to aquire another amp first. Might take awhile, but thanks for your input.
Robt. |
I suppose I'll just have to try it. |
If as I think the amps are bridged, what happens to the channel that isn't available when using the RCA adapters? It would be half of the amp's power being sent to ground. |
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Thanks Atmas. But why can't I use one channel of the amp for the positive input and the other for the negative of an XLR to convert the amp to balanced? I would use the chassis for ground. |
I don't see why I would need an input transformer Al. |
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