This is almost embarrassing to ask on THIS forum. LOL But here goes..... How can I add XLR inputs to a given amplifier, which only has the usual RCA inputs? Would it be different with different amplifiers? On one of my two Threshold S-300's it has the "E" mod, which includes XLR's, and RCA's, and a switch to choose between them. That's what I would like to do to other amps.
I'm shopping for a third amp, so that I can tri-amp with me DQX-2496 xover. This would broaden the field a lot, because I would like the third amp to be balanced also.
Many thanks!
I'm shopping for a third amp, so that I can tri-amp with me DQX-2496 xover. This would broaden the field a lot, because I would like the third amp to be balanced also.
Many thanks!
Why not just buy an XLR-RCA adaptor? There is no benefit adding XLR connections to a device that already has RCA other than cosmetic reasons.
ss
For a solid state solution, you could use an INA134. This will take the balanced XLR signal and convert it to single ended which then goes right into your amp to use normally. It should help with long cable runs. I put XLR inputs on my Gainclone using this technique.
Here is a schematic of what i did.
For a solid state solution, you could use an INA134. This will take the balanced XLR signal and convert it to single ended which then goes right into your amp to use normally. It should help with long cable runs. I put XLR inputs on my Gainclone using this technique.
Here is a schematic of what i did.
If I understand you correctly you just want a way to hook up XLR lines to your RCA-only amp, that is just adding the connectors without additional electronics.
That means your amp has no means for a balanced signal and therefore it also has no real advantages (except if you are living in extremely noisy area so that improved interference rejection on the balanced 1m interconnect helps you a bit).
Have fun, Hannes
That means your amp has no means for a balanced signal and therefore it also has no real advantages (except if you are living in extremely noisy area so that improved interference rejection on the balanced 1m interconnect helps you a bit).
Have fun, Hannes
Thanks for your input everyone! 🙂 (I couldn't resist.) Seriously though, I've been using adapters similar to this:
http://www.avcable.com/Merchant2/me...Code=AA-35-461&Category_Code=XLR-ADAPTER-MALE
My idea of adding balanced inputs was to do away with the extra connection between the balance out, and the adapter. I'm thinking I should just do what I've been doing with the adapters. Here is another question: Does anybody know of GOLD PLATED adapters like the one in the pic, only gold? I mean gold on the rca part, and on the XLR pins. Cardas makes some, but they're $80 each. The cable I'm using is Mogami OFC, and I hate to dumb it down to the cadmium, or what ever metal that is on the connectors that I'm using now.
http://www.avcable.com/Merchant2/me...Code=AA-35-461&Category_Code=XLR-ADAPTER-MALE
My idea of adding balanced inputs was to do away with the extra connection between the balance out, and the adapter. I'm thinking I should just do what I've been doing with the adapters. Here is another question: Does anybody know of GOLD PLATED adapters like the one in the pic, only gold? I mean gold on the rca part, and on the XLR pins. Cardas makes some, but they're $80 each. The cable I'm using is Mogami OFC, and I hate to dumb it down to the cadmium, or what ever metal that is on the connectors that I'm using now.
I still don't get what you want to do, after seeing that adapter you showed.
You have a source and several power amps that you want to connect in parallel, right?
Some of those amps have balanced inputs (with XLR) and others with unbalanced inputs (RCA).
1) So you want to add balanced inputs (active) to the unbalanced inputs?
2) Or you want just to add XLR connectors to the unbalanced inputs, not adding a balanced interface?
You have a source and several power amps that you want to connect in parallel, right?
Some of those amps have balanced inputs (with XLR) and others with unbalanced inputs (RCA).
1) So you want to add balanced inputs (active) to the unbalanced inputs?
2) Or you want just to add XLR connectors to the unbalanced inputs, not adding a balanced interface?
DaveThreshold said:
All you need is a Greenlee socket cutter, a little round file and an electric drill:
An externally hosted image should be here but it was not working when we last tested it.
A real answer:
Please post the specific amps that you have. Are they all Threshold?
Some amps can be electronically converted to balanced input without much difficulty. Others are not so simple.
To drive most amps that can be converted requires changing the feedback configuration and then the input drops significantly in impedance. Sometimes the performance or stability of the amp can be affected negatively.
The solution using a balanced to SE opamp has some merit, but a whole lot depends on the rest of your system and what it can reallyresolve or not. For most folks the IC that does the trick is sufficiently good. (especially if you are driving things with any Behringer gear).
You can also build a sophisticated circuit using opamps to do the same thing as the single opamp converter chip.
Then too, you could go whole hog and build it up out of discretes... but we can ignore that for now.
The Jensen transformer is a good way to go. I think it "mellows" the sound a bit, but that is not bad for most people's systems anyhow. Go to the Jensen site and see what they offer - they have schematics too...
_-_-bear
Please post the specific amps that you have. Are they all Threshold?
Some amps can be electronically converted to balanced input without much difficulty. Others are not so simple.
To drive most amps that can be converted requires changing the feedback configuration and then the input drops significantly in impedance. Sometimes the performance or stability of the amp can be affected negatively.
The solution using a balanced to SE opamp has some merit, but a whole lot depends on the rest of your system and what it can reallyresolve or not. For most folks the IC that does the trick is sufficiently good. (especially if you are driving things with any Behringer gear).
You can also build a sophisticated circuit using opamps to do the same thing as the single opamp converter chip.
Then too, you could go whole hog and build it up out of discretes... but we can ignore that for now.
The Jensen transformer is a good way to go. I think it "mellows" the sound a bit, but that is not bad for most people's systems anyhow. Go to the Jensen site and see what they offer - they have schematics too...
_-_-bear
bear said:
Lundahl is also worth investigating.
But using a transformer is not that simple either. Other mods might have to be implemented on the source.
An important point no one has mentioned; Converting from unbalanced to real balanced also increases the level 14 db! Just because a piece of gear has XLR conectors dosnt mean its balanced. Check the manual, and see what level. (Profesional balanced is at +4, most consumer gear is -10dbu) the other catch is some gear is pin 2 hot some is pin 3. The real question is do you need these to be balanced, probably not. In typical consumer applications (including tri-amping)the unbalanced -10 interconects are as good as the balanced.
That's why I asked what were we really talking about.
DaveThreshold did not make it clear to me what we are dealing with. An unbalanced to balanced situation or a simple connector question.
DaveThreshold did not make it clear to me what we are dealing with. An unbalanced to balanced situation or a simple connector question.
h_a said:
carlmart said:
Here, I'll try this again. I'm using two Threshold S-300 stereo amps, and I will be adding a third amp to tri-amp with. One Thresh has balanced inputs which I'm connecting right off of the crossover, and the other has RCA inputs which I'm using the adapters shown in my second post above. I will be buying a third amp, but I'm not sure which yet. I thought that I could mount two XLR jacks to any amp that doesn't have XLR inputs connecting the + and - from the RCA input wiring inside the amp to the new XLRs which I'll mount on the amps that only have RCA's. I GUESS it wouldn't be a true balanced line, but I wondered if it was possible without extra circuitry. This would at least do away with one adapter per chan, on at least one amp.carlmart said:
I hope that makes things a bit more clear. I guess my 1st post was more vague then I thought. 🙂
All depends on the particular signal source you connect to an unbalanced input that pretend to be balanced XLR.
If you ground the "cold" pin of XLR...
Variant 1: you loose nothing, or 6 dB: transformer output, or "auto-balancing output", or just a symmetrical output pair with 300 Ohm each.
Variant 2: you are loosing an output stage of your signal source.
If you don't connect the "cold" pin, you have again possible variants depending on output of your signal source: getting 6 dB less, or getting nothing except higher frequencies coming through parasitic capacitance.
If you make a real transformer balanced input you loose nothing, but gain a S/N ratio (ground loop eliminated, power loss is less).
If you ground the "cold" pin of XLR...
Variant 1: you loose nothing, or 6 dB: transformer output, or "auto-balancing output", or just a symmetrical output pair with 300 Ohm each.
Variant 2: you are loosing an output stage of your signal source.
If you don't connect the "cold" pin, you have again possible variants depending on output of your signal source: getting 6 dB less, or getting nothing except higher frequencies coming through parasitic capacitance.
If you make a real transformer balanced input you loose nothing, but gain a S/N ratio (ground loop eliminated, power loss is less).
DaveThreshold said:
Two final questions:
1) Are you sure that crossover has real balanced outputs? What brand and type is it?
2) The third amp does have a balanced option inside to be wired or you will just be wiring an unbalanced interconnection with XLR?
bear said:
THAT Corp line drivers/receivers have a bit of a performance edge over ADI's if you choose to go this route. You can get them from Newark (but they ship from Farnell in the UK).
The PAS preamp with the XLR's uses Sowter 3575C transformers. I am working on using Silonex LDR's for switching between the RCA inputs or balanced inputs to the ImPASSe preamp.
An externally hosted image should be here but it was not working when we last tested it.
DaveThreshold said:
Still not very clear...
The second Threshold is the same as the first, but only had RCA inputs?
Why not OPEN the Threshold that HAS XLR inputs (factory stock?) and see what was done?? IF it was done properly (and you can post images and circuits and ask here) then why not just mod the second one the same way??
For the third amp, you have two choices:
- figure out what to do on any given amp of your chosing
- buy an amp that already has balanced input w/XLRs
_-_-bear
PS. jackinnj, hope ur goining to lose those front panel switches, tone controls, volume pot and balance control as well as the old carbon resistors on the board?
PPS. Then why not lose the chassis and start a preamp from scratch?? (seriously...)
bear said:
I have 6 preamps -- the PAS was found in a dumpster WITH an ST-70. The volume pot is an ALPS. Most of my listening pleasure is done with a modded Adcom GFP-565!
All the switching is going to be done via LDR's...and the tone controls can be switched in and out.
The PAS Preamp is fitted with an Impasse board, Maida regulator, modded RIAA and has balanced output so that it can drive a pair of F4's in balanced mono. It has balanced in 'cause I still have quite a few of XLR's left over from a Linn Preamp I had 15 years ago.
It's much the same reason that folks will hot-up a Dodge Challenger. It looks like a Dodge, but goes very fast in a straight line.
It seems to me that what you really need to do is match the gain between your 3 amplifiers. If the gain (using whatever inputs you care to use) is different you are going to have problems.
Adding an XLR to an RCA without any transformer or active circ will do nothing.
You should load each amp with the same resistor driven by your pre with the same vol. to see if the voltage across the resistor is the same. If it is you have a good setup. The bal one may be 6db or more higher than the rest, but adding xlrs with pins grounded is not going to equalize the situation.
Adding an XLR to an RCA without any transformer or active circ will do nothing.
You should load each amp with the same resistor driven by your pre with the same vol. to see if the voltage across the resistor is the same. If it is you have a good setup. The bal one may be 6db or more higher than the rest, but adding xlrs with pins grounded is not going to equalize the situation.