Rogue Audio Cronus Problems

[crappyjones123]

I turned on the amp after about a week and a half of work being done on the house and attached is a short clip of what I heard. Recorded with the iPhone mic about 2 inches away from the driver but its a pretty close representation of the issue. 

 

1. I turned it off after 10 minutes of warm up and it still making the same noise. 

 

2. Turned it on again and let it warm up for 15 minutes. Still the same noise. Biased the tubes. Still the same noise. 

 

3. The noise is equal in both channels from what I can tell. 

 

4. The noise if constant with two  different sources. 

 

5. All tubes are lit except for 12ax7s. I don't see anything in them but I don't know if this is normal behavior for them. 

 

Don't have a tube tester or access to one but I have put on maybe 100 hours of listening time on them. The previous owner mentioned 200 of his own. Anyone think one/more of the tubes went? Any way to troubleshoot this without another tube set? Without knowing which tube it is, a replacement set will run close to $500 so I'd like to avoid it if possible. I have a dmm that I can use with detailed instructions on where to put the probes. 

 

Suggestions anyone?

Memo.mp3

Edited May 5, 2013 by crappyjones123

[morphsci]

You should be able to get a set of 12AX7s for a hell of a lot less than $500. I would start with those.

Edited May 5, 2013 by morphsci

[crappyjones123]

the m4a file wouldn't attach so I converted it to mp3. sounds the same as the original. 

[spritzer]

A new ECC83/12AX7 is less than 15$ so that would be my first step. 

[Dusty Chalk]

That is definitely not normal behavior for 12AX7's, I would start with that. But it may not be the tubes, so definitely get new tubes to make sure which it is.

I mean, if it was Stax, I would understand the farting sounds...

[jp11801]

CJ I've got a few 12ax7s around the house and could probably either stop by or  meet you to loan 1-2 to you to test the amp out. 

 

PM if you need a hand, no worries if you have it under control at this point

[n_maher]

CJ, if you want the tubes tested you can shoot them up my way and I'll run them through the gamut and let you know what I find.

[crappyjones123]

John, thanks for the kind offer. I think I'll take up Nate on his to see if more than one needs to be replaced. Pm incoming. Thanks again guys.

[ktm]

So, a happy ending? Or agony?

[crappyjones123]

Haven't had the time to get the tubes shipped. Will try to get them out when time permits soon. 

[kirkwall]

(Apologies if this comes way too late to be of any use -- just realized that I replied before checking date of last post, I'm afraid.)

 

I've got a Cronus Magnum (bought new) which shipped with an 12AX7 that measured way out of spec and blew within the first week. It did sputter some before giving up the ghost but remained lit. It was reolaced straight away by the factory. Have you been in touch with Mark @ Rogue? He's generally easy to reach and helpful, whether the unit was bought new or used.

 

I ended up subbing in lower-gain but seemingly pretty sturdy 5751s and find them a fair bit quieter. Love the amp though. Drives my Harbeth M30.1s really nicely, despite the noisy HP section.

 

best,

 

k

Edited June 22, 2013 by kirkwall

[crappyjones123]

I just got a new full set of tubes - winged c el 34s and jj 12ax7s and 12au7s and now I am getting very low volume from the left channel and a loud buzzing sound from the left channel as well. No pops though. The right channel has an audible buzz as well but not as loud as as the left. No pops out of the right channel either but the sound out of the right channel is normal. When setting bias, V1 and V2 shot past 100. Once I let the amp warm up, I reset it back to 35 but V1 kept rising until it got to 55 when I shut it off.

 

I have emailed Mark to see if I can send it to him to take a look at. Anyone have any ideas or would be willing to look at it? The amp is not under warranty anymore so I expect the repair estimates to be astronomical from Rogue Audio.  

[dsavitsk]

Is there noise from the pre and fixed outputs? Do you have other tubes that do work? Or at least work better? Do you have a schematic? Can you open it and take lots of detailed pictures?

[crappyjones123]

Tube amps are a freaking emotional roller coaster I tell you. An hour on the phone with Mark, we were able to narrow it down to 4 super duper shitty tubes (ordered new but shitty nonetheless). He made me do some voltage checks and everything was rock solid which is why he was apprehensive in me sending it to him in the first place. He made me move tubes around and try the older ones mixed in with newer ones and finally found a combination which has slight hiss in both drivers but a buzz in the left. He offered to sell me some tried and tested tubes in the very amp I am using to ensure smooth and quiet operation. Going to go with that and try to return the shitty ones. Just glad the amp is in perfect condition. 

[VPI]

I got sick of constantly having those calls with Mark and gave up on my Rogue stuff a long time ago.  Still have an old Magnum 88 power amp laying around somewhere that has not worked forever.

[crappyjones123]

I haven't really had reason to complain against the amp other than the tubes (which isn't the amp's fault). Given how hard it is to test tubes without a tester, it can cause a little over exaggeration of the issues experienced (in my case for sure). I love this amp when I don't have issues with the tubes. Listening to it right now at low volumes and it sounds glorious. Might keep it after all and deal with the heat. We shall see. The winged c el34s are mighty nice. 

Edited February 14, 2014 by crappyjones123

[crappyjones123]

Is this normal? 3 of the 4 el34s have these purplish spots on both sides of the tubes. 

[crappyjones123]

Anyone?

[dsavitsk]

Is this normal?

 

yes