Tube advice / suggestions needed..

pjdami

I've been demoing a Rogue 88 power amp from my dealer since this weekend in my two channel rig. Source is a Jolida tube output stage cdp and the preamp is the B&K ST5 solid-state. Speakers are Polk LSi 9s and Spendor S8s. I'm going to have to decide if I want to buy this particular unit, but looks like I've "crossed the road" to the other side for now at least. Review to come after I've had more time with it.

Thanks Organ for recommending the tubestore.com for a source of tubes.

Now what are some good tubes to try out?

The Rogue has 4 KT88s, 2 12AX7s, and 4 12AU7s. Currently it has Ei 12AX7s but I can't readily tell what the power tubes are or the 12AU7s.

I've read in the past threads that the Electro-harmonix are good sounding tubes. Other choices are SED (Svetlana), Tesla, Sovtek.

Any opinions on how the sound characteristics of these different manufacturers sound and what are good matches for the signal / power tubes?

thanks.
Paul

edit: wrong number of tubes.

organ

Hi Paul,
Welcome to the other side:D. If your looking at new production tubes, Svetlana is the best IMO. For both my signal and power tubes, the Svets sounds the best. triodeelectronics have the Svet 12AX7. You can try NOS signal tubes. They're much cheaper than NOS KT88. Electro Harmonix is also a very good brand. Don't forget that 12AX7 is the same as ECC83 and 12AU7 is the same as ECC82.

Ask your dealer if you can use EL-34 tubes as a substitute to the KT88. Some amps allow you to do this. EL-34 are much ceaper than KT88's.

Different brands will have a different sound signature. It's best to try them all out and make your own combos that sounds best to you. It's so much fun. So far, I'm still in love with the sound of the Svet 12AX7 and Mullard 12AU7 in the pre.

Can't wait to read the review.


Maurice

Frank Z

Pjdami,
The ASL that I bought from Hoosier had 4 relatively new Svetlana KT88's. Very rich across the board. Granted I haven't experimented with any other tubes (yet), but so far the ASL sounds incredible as is. One thing I did learn from this and other forums is the importance of buying matched tubes, but I'm sure you already knew that....so I'll shut my pie hole.;)

pjdami

Thanks Maurice and Frank for the quick replies.

I looked over at triodeelectronics and the quad matched Svetlanas are now called SED due to legal disputes with the name brand here in the USA. Maurice are these the power tubes you are running?? The SEDs?

I'm running 12AX7 Svets on my Jolida cd player and I love that cd player.

The Rogue has a self adjusting bias because it uses a cathode type.. lots for me to learn here. Bottom line is that I don't have to adjust the bias! It also has a triode mode (40 watts) and Ultra linear mode settings (60 watts); some people say the triode mode is sweeter but I haven't tried it yet.

Very nice tube amp and built like a tank. Weighs 55 lbs! 20 reviews over at audioreview.com and all of them are 5 / 5.

The fan is a tad bit noisy. It flows 50 scfm. I can hear it during very quiet passages and between songs on a cd. I'm going to have the dealer replace it if I buy the amp. The fan spec is 28 db and if I can hear it from across the room its gotta be louder than that. I may have to try out some Sorbothane feet to isolate the amp from the cabinet since the wood may be exasperating the fan noise. Minor complaints but I'm picky.

Right now looks like a keeper!

pjdami

another from the inside.

organ

Paul,
BEAUTIFUL set up man. I love the way all the colors match. That amp looks awesome!

What kind of difference are you hearing on the triode mode? It's suppose to be better.

Here are some tubes you can put on your list:

http://www.thetubestore.com/svetlanakt88.html
Heard great things about this one http://www.thetubestore.com/ehx12ax7.html

And since you only need two AU7, you might want to try out a pair NOS: http://www.thetubestore.com/tungsramecc82.html I own a pair of RFT which pretty much have the same sound signature as the Tungsram. My second favorite next to Mullard.

Let us know how the tubes sound. So is there a tube pre coming?

Maurice

polkatese

Very nice amp, Paul! do let us know how do you like it, especially in comparison to your 125.2...

pjdami

Thanks Maurice for the tips and links. Exactly what I was looking for. I know the KT88 have to be "quad - matched" but do the signal tubes have to be "pair" matched or can I purchase them individually? They are sometimes listed as "matched" pair but not always.

See the yellow wire kind of hanging on the back of the amp where the RCA input jack is? Well the two yellow wires (L & R) have to be connected for 4 ohm speakers and the other wire removed. Right now I have just been running on the 8 ohm configuration with the Spendors. I do plan on trying out the LSi 9 in the 4 ohm configuration as well.

I will try the triode mode of operation tonight. Some people claim it does sound better; others can't tell. The triode mode is supposed to have less distortion because the characteristic curve of the tube is more evenly spaced out. Again, lots for me to learn here.

Polkatese,

The B&K amp holds its own against it. I don't want to jump to conclusions too soon, but the tube amp definitely sounds "different" than the SS amp. Really an unfair comparison since the Rogue retails for nearly double what the B&K retails for. I like a comment I saw about the Rogue amp somewhere, "this amp is what being an audiophile is all about."

Paul

organ

Paul,
The signal tubes don't have to be matched pairs. I believe they tell you the reson why in thetubrestore's FAQ section.

I can't wait to hear your impressions of the LSi being driven by the Rogue. When I had the LSi9 hooked up to the Dyna, the smoothness and sweetness were all there but it lacked micro dynamics and slam. It still dug very deep for the low frequencies. The KT88 tube is suppose to have more guts than EL34's so the LSi might work perfectly on them. The 'chestiness' you've been complaining about on the 9's should completely dissapear on tubes. Well, that's what happened to me anyways. Let me know if it goes away.

So have you decided on which tubes you're ordering? Read a lot about them and take your time. One thing that's reall helpful is to go to audioasylum.com's tube forum and do a search for the type and brand of tubes. ex "Svetlana kt88". You will find a lot of opinions. I used to spend hours reading about a particular tube before purchasing.

One thing you will LOVE about tube swapping is the change in sound. Sometimes it can be so dramatic that you'd think you bought a new piece of equipment. As long as there are tubes to try out there, I doubt you'll be looking for a new amp.

It will be months before I have tube sound again:(. I decided to skip the new int purchase and save up to get the Dyna rebuilt and modded. The ASL will probably get a mod too if I still have change. People who had their Dyna rebuilt and modded said it will blow away the int I was planning to buy (ASL or Jolida).

Maurice

pjdami

Hey Maurice,

I ordered the signal tubes today.. kind of went on a whim and ordered some NOS JAN 12AX7WA and German 12AU7-RFT-MP. The guy at Triode told me that these were selling like crazy.

Triode electronics was out of the Svetlanas so I have a few other stores I'm looking at for those.

I actually do have 4 12AU7s in my amp instead of two that I misquoted above.

I'm running like entry level Sovtec tubes right now in the amp. The 12AX7s are Ei brand (which seem to be well respected).

Can't wait to hear the difference in some "better" tubes. The guy at Triode was recommending that I could go with the Electro Harmonix KT88 instead of the Svetlanas ... not that he was pushing them on me, but I've just read too much good feedback on the Svetlanas that I really want them for the power tubes. Don't you have both?

Paul

organ

Paul,
You picked some great tubes. Ned from Triode is very helpful and is a supporter and regular poster at audioasylum. What brand are those JAN X7's? JAN are military tubes which stands for Joint Army Navy. They are very well built and can survive a nuclear blast and operate at very high altitudes:).

The RFT are also great tubes. They have a large number or loyal followers. Conrad Johnson used to ship their equipments with RFT tubes. They sound less tubey but have great control and very good detail.

Yeah, I have both Svet (SED) and EH. I'm sure the sound signature of their EL34 and KT88 should be similar. IMO, Svetlana is has great body and gives you 'texture'. You will hear so much detail in the mids especially on vocals. I was able to hear the singer's lips smacking and the sound of their saliva as they opened and closed their mouth. They have plenty of bass too. Madmax didn't like them as much because the bass was powerful and controlled. He prefers the 'flabby' bass.

The EH have a very syrupy sound. They're so damn smooth they sound fake!(in a good way) It had the least amount of bass and less sparkle in the top end. But when it comes to soft relaxing music, they really give you a magical experience. They sound amazing when I listen to Sarah Brightman and other classical/opera stuff. Their 'fat bottle' 6CA7 (EL34 substitue) sounds different. A lot of detail and power. Not sure if their KT88 sounds more like the EL34 or 6CA7. You might want to e-mail Triode and ask Ned.

Let me know how the new tubes sound when they arrive. Remember to let them warm up for about 30 mins before critical listening. Enjoy.

Maurice

pjdami

Maurice,

Received the signal tubes today. The JANs are Phillips JAN 12AX7WA NOS tubes. I put them as well as the RFTs in the amp this afternoon. My power tubes, I'm going to have to go with Electro Harmonix as it is considered a "safer" tube and what Rogue recommends as they have the best parameters for the cathode bias that the Rogue 88 has built in.

I should be getting the EH KT88 in a couple of days.

I was kind of nervous when I fired her up.. but you know even for a newbie like me to tubes, tubes are part of our everyday life really. As in lightbulbs. So I was like, nothing to be nervous about (except that the NOS are like $20 lightbulbs..LOL).

I can't really tell if I hear a difference between the Sovtek / Ei that I was running compared to the JAN / RFT to be honest. It all sounds good! LOL...

Thanks for the tips.
Paul

organ

Congrats Paul. Yeah, they're very expensive light bulbs:D . Not sure why you're not hearing a difference . Did you let the amp warm up before listening? I know you've heard this so many times about speakers, amps, etc but they say tubes need to break in too. Using the RFT made a big difference in my pre. One thing you can try is to get used to the sound of your new tubes, then place the stock ones back in. I'm sure you'll hear a difference. The power tubes makes a bigger difference.

Let me know if the sound improves over time with the new signal tubes. Also, you can try a different combo like Sovtek/RFT or JAN/Ei.

Does the intruction book for your amp mention about the amount of current(mA) needed for power tubes? If you're buying from the tubestore, you should mention the plate current you need. Is your amp auto bias or fixed bias?

Maurice

pjdami

Maurice,

My amp is cathode self biasing. No info in the instruction manual about the current. I emailed Rogue and they emailed me back the next day with what they recommend for the amp. The signal tubes I kind of went on my own based on your input and some actual Rogue owners that I encountered on the net. One guy recommended RCA 12AX7 black plate / Tele' 12AX7 smooth plate and for the 12AU7 RCA Clear Top or the RFT 12AU7 (the one's I just put in). He said that I could use the Svetlana KT88 as he used them with no problems.

Believe me the sound is gorgeous. Not complaining at all. Yeah, I always allow the amp to warm up for about 10 minutes before I listen critically. Tube break - in I've read about that too and some tubes can take 100 - 200 hours from what I've read.

The other problem with comparing is that for safety purposes, I power down the amp and wait about an hour to disconnect the power cord before getting at the inside of the amp to ensure that all the electrical potential is gone. The manual repetitively states to do this to avoid potential fatal electrical shock. So with the long delay here and the careful time required to install the tubes it is kind of hard to hear subtle differences. Like I said they all sound good! I'm sure that in time I will make some impressions of what differences I'm hearing. Not too worried about all that really, just enjoying it.

I'm really impressed with the bass from this amp. Its actually better than an Audio Research tube amp that I listened to at the dealer. And the mids and highs.. well you know how sweet those sound with tubes.

organ

That's cool. So you should be able to use any power tube because of the auto bias.

The RCA black plates are very rare and expensive. The Telefunken smooth plates are more rare and cost even more. The Ei 12AX7 are copies of the Tele smooth plates. The tubestore had RCA clear tops but I think they're out of stock. I really wanted to try them too.

Not sure about the circuit design of your amp but I'm sure glass is not a conductor, so if you open up the amp and remove the tubes after a few minutes, you should be fine as long as you don't touch anything else other than the glass. I've swapped tubes minutes after turning off the amp or pre. I just wait for them to cool down, but you might want to e-mail Rogue just to make sure.

I was also very impressed with the bass on my Dyna but adding the ASL really gave it that extra punch. Even with SS amps. I find that tube pre amps can be much more dynamic.

Maurice