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Rogue cronus as a power Amp adventures

J

Jimswms

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First post. Thanks for allowing me to lurk :)

Happy Rogue Cronus Magnum 2 user. I came across a McIntosh C34v preamp I couldn't refuse. Other than broken glass, it's in great condition. Per Rogue Audio, I have it running through my Cronus line in (cd). Volume set at 12 o'clock. I understand this is not an ideal scenario. Sounds amazing, and has a depth that just isn't there with just the Rogue. I'm not good at explaining what, just a certain something I'm really liking with a variety of music. I want to explore this further

I guess I'm wondering if anyone else is running a setup like this? My understanding is the middle 12AU7 tube is the preamp tube, and the others are purely for the Amp? Just trying to better understand what is coming from the Amp, and what is the preamp. This is all just for fun, I see my Rogue heading for a dark upgrade at some point. Seems the mcintosh and rogue preamp are competing with each other at this point, but it's working soo

Is the Rogue cronus an Atlas with the middle tube added? Just scratching that McIntosh itch is all.
Have to say, it sounds quite nice as is. Just thinking of different options to mess around with. It's not that I'm trying to fix anything, just tinkering

Thanks for any insight
 
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I'm guessing the middle 12AU7 is the gain tube and the other 12AU7's are part of a long tale pair, maybe one is a buffer for the phono preamp, etc.?
If you email Rogue and ask them about the other 12AU7's they'll get back to you pretty quickly.
Does the output of the preamp have so much gain you need the volume control on the Rogue amp turned down 1/2 way to get enough range of motion with the volume control on the preamp? I have two tube amplifiers with added volume controls. I just turn the volume controls all the way up when using a preamp with them.
The only preamp in the Cronus is for the phono. The volume control is connected at the input jacks. I would use the phono input on the McIntosh if you have a turntable. Its probably better than the phono preamp in the Cronus.
The Cronus has a SS phono preamp on a small PCB inside the amp.
 
Lavane said:
I'm guessing the middle 12AU7 is the gain tube and the other 12AU7's are part of a long tale pair, maybe one is a buffer for the phono preamp, etc.?
If you email Rogue and ask them about the other 12AU7's they'll get back to you pretty quickly.
Does the output of the preamp have so much gain you need the volume control on the Rogue amp turned down 1/2 way to get enough range of motion with the volume control on the preamp? I have two tube amplifiers with added volume controls. I just turn the volume controls all the way up when using a preamp with them.
The only preamp in the Cronus is for the phono. The volume control is connected at the input jacks. I would use the phono input on the McIntosh if you have a turntable. Its probably better than the phono preamp in the Cronus.
The Cronus has a SS phono preamp on a small PCB inside the amp.
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Thanks for the reply.
I have volume set at 12:00 simply because it's what rogue recommended. I think I read somewhere that the phono section on a Cronus is not tube. I think that center 12au7 is the preamp tube. Rolling it definitely makes a big difference

Phono is currently going through a Darlington labs phono stage, although at some point I'll hook it up to the Mc for fun.
 
Yes, the phono stage is solid state in the Cronus. The center driver tube is the voltage gain tube, so it will make the most difference in over all sound along with the power tubes. I have a VTA ST-70 and the center gain tube makes the biggest difference as well. The other two driver tubes are for the long tail pair. Trying different 12AU7's in those two spots made little if any difference that I could tell in the overall sound of the amp.
The Cronus and Atlas are nice amps. Rogue is known for great support too.
 
does it have a real preamp stage, or is it just a phono preamp, input selector, and volume control running right into a power amp? If its the second one, then running an external preamp really isn't any big deal, just use the volume control as an input sensitivity adjustment.

honestly even if its got a legitimate line stage you could do that. Or if you're up for having some mods done, it probably wouldn't be a big deal to fit it with a set of preamp out / main in jacks that would allow you to bypass the internal preamp completely.
 
gadget73 said:
does it have a real preamp stage, or is it just a phono preamp, input selector, and volume control running right into a power amp? If its the second one, then running an external preamp really isn't any big deal, just use the volume control as an input sensitivity adjustment.

honestly even if its got a legitimate line stage you could do that. Or if you're up for having some mods done, it probably wouldn't be a big deal to fit it with a set of preamp out / main in jacks that would allow you to bypass the internal preamp completely.
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Unless they've made a change, the Cronus comes with a SS phono preamp installed inside the chassis. That what I read a couple years ago in the specs Rogue listed.
 
Lavane said:
Unless they've made a change, the Cronus comes with a SS phono preamp installed inside the chassis. That what I read a couple years ago in the specs Rogue listed.
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That is correct. I researched this model, auditioned one, but ended up going in a different direction. Very nice integrated amplifier.
 
Lavane said:
Unless they've made a change, the Cronus comes with a SS phono preamp installed inside the chassis. That what I read a couple years ago in the specs Rogue listed.
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what about between the phono stage and the power amp? Meaning are those other inputs just straight into the main amp through the volume pot or is there an extra stage in there as well? Some modern "integrated" amps are just power amps with a source selector and a volume control, so you could easily run an external preamp with no fuss. I don't know if this one is that way or not.
 
gadget73 said:
what about between the phono stage and the power amp? Meaning are those other inputs just straight into the main amp through the volume pot or is there an extra stage in there as well? Some modern "integrated" amps are just power amps with a source selector and a volume control, so you could easily run an external preamp with no fuss. I don't know if this one is that way or not.
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I believe this one is just that. A power amp with a source selector and a volume control. The Cronus is the same amp as the Atlas. Rogue just added a source selector, volume control, SS phono pre PCB, and a headphone jack to the Atlas and called it a Cronus. Both amplifiers use the same type and number of tubes.
 
gadget73 said:
Easy enough then, just adjust the control on the amp so the volume on the external preamp is in some sort of a useful range, feed it in to whatever non-phono input is desired.
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This is what I've done. I wonder if one preamp sorta overrides the other? I'm essentially using both Pre-amps at this point. It sure does sound good, but I have no way of knowing if I'm limiting what the c34v can do in this scenario. It does sound better to my ears than the Rogue alone so there's that
 
If the Cronus doesn't have a dedicated line stage in addition to the power amp circuitry, then you aren't really using two preamps. You're just using one preamp fed into an amplifier that has a level control, which many power amps do actually have.

ultimately though if it sounds better to you, run with it. Its not going to damage anything.
 
I have several solid state power amps with gain controls. You just adjust them so you have plenty of range with the volume control on the preamp.
You could also adjust the volume control on the Cronus so when you max out the volume on your preamp its right before you hear any distortion through the speakers.
 
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Alright, you guys have me thinking. Tonight I'll mess around with this. Maybe, I can have some form of lazy volume remote afterall:cool:
 
I have a few tube amps with volume controls. If using a preamp to feed to tube amp, I just turn the volume knob on the amp to maximum and adjust the volume with the preamp. Have never run into a problem so far.
 
BmWr75 said:
I have a few tube amps with volume controls. If using a preamp to feed to tube amp, I just turn the volume knob on the amp to maximum and adjust the volume with the preamp. Have never run into a problem so far.
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When using a CD player connected to the preamp in my main system the output is a bit hot. Anything passed about 9:00 on the volume control gets really loud. I have a volume control added to my ST-70 that I can turn down to get more range with the preamp master volume control. With my other amplifiers I have to turn down the gain controls on my preamp to have more range with the master volume control. But with most sources I run the volume control on the ST-70 wide open though.
 
The specs suggest to me the line inputs may not be preamplified. But, I'm gauging relative to solid state integrateds that typically have almost an order of magnitude higher (lower number) input sensitivity.

Input sensitivity 1.0 V RMS
Phono 45dB gain +/- 1dB 20Hz – 20KHz
 
whoaru99 said:
The specs suggest to me the line inputs may not be preamplified. But, I'm gauging relative to solid state integrateds that typically have almost an order of magnitude higher (lower number) input sensitivity.

Input sensitivity 1.0 V RMS
Phono 45dB gain +/- 1dB 20Hz – 20KHz
Click to expand...
Can you explain what this means? "sounds good" is where I'm at :)
 
input sensitivity is how much signal is needed to make full output power for one of the not-phono sources. There really isn't a standard for this, especially if you look at old gear but somewhere in the ballpark of 1v is fairly typical, though 0.3 to about 2v is not uncommon. Its basically where I'd expect for something that doesn't have an extra line stage amp circuit built in. Its not so sensitive that an external preamp is likely to overdrive it or cause distortion problems or anything like that.

Phono gain in the 40dB range is also typical. Thats just the difference required for the RIAA EA curve, so the actual gain varies considerably by frequency. Its around 40dB at the bottom end. Doesn't really matter since you aren't using it.
 
gadget73 said:
input sensitivity is how much signal is needed to make full output power for one of the not-phono sources. There really isn't a standard for this, especially if you look at old gear but somewhere in the ballpark of 1v is fairly typical,
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For a power amp.

But, the Cronus is an integrated amp and in most cases for integrated amp, receiver, etc., line input sensitivity is more like around 150mV.

We're on the same page re. likely no preamplification on the line inputs so just commenting/clarifying the differentiation on input sensitivity.
 
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