[cfcubed]

RE: ICH - Don't need to get into it, but ICH, even w/o any heatsink, should not fail if typical/recommended tubes are used & there is some ventilation holes in the case  (e.g. 12au7 series heater draw is about 300ma).  
Nevertheless, because I'm a heatsink fan I usually fit a small one on ICH (e.g. even part of a small heatsink e.g. a "U" cut into an "L").  Do this also because I occasionally run tubes w/higher heater draw than recommended (600ma max series draw).
 
RE: set of tubes -  That's one killer batch you mention there arteom.  IMO I hear a "house sound"  amongst Amperexes / BB 6DJ8s like those mentioned.  Glad you guys are enjoying this  I mentioned some of my favs w/my "new" HD600s here:
http://www.head-fi.org/forum/thread/417322/cavalli-compact-tube-hybrid-cth-tube-tweak-thread/540#post_7016862
Quote:

Originally Posted by arteom /img/forum/go_quote.gif
Yeah, I needed to switch out the ICH recently and maybe need to check the soldering on that. 
 
Got a set of tubes myself just a few weeks back on ebay, got really lucky. Got one of each: Holland Amperex ecc88, Amperex PQ white label 7308 USA, Amperex PQ D Getter USA 6922, RCA West Germany 7308, and one mystery tube that perhaps outperforms all in resolution, though a little lacking in the bottom end. Have also a Siemens CCa I got a week before that. They really better the value of the CTH.

 

[Mullet]

I'm going to get this puppy going again because of the new CTH Rev A currently being built.
 
Anyone in the past use either 12AY7 or 12AV7 tubes? They look like they're higher gain tubes of around 37-40 mu. The 4BQ7 tubes I'm currently using work fine and they have the same amount of gain. If no one has experience with them I might try and win a cheap one on the bay to give it a shot.
 
Also, what about 5687 tubes? They seem to have the same amount of gain as a 12AU7; 20 mu, but have a higher running current of 450mA. This seems within spec.

 

[cfcubed]

Quote:

 
Anyone in the past use either 12AY7 or 12AV7 tubes? <snip<
 
Also, what about 5687 tubes? They seem to have the same amount of gain as a 12AU7; 20 mu, but have a higher running current of 450mA. This seems within spec.

IIRC a higher-gain 12a?7 variant was tried here (12at7?) and it didn't work well.  If anything we are looking for gains equal to or lower than 6922 I think.  Most of what we know about CTH tube compatibility is in my old tube compat post (now linked to in my sig).  There are usually hundreds of tubes on ebay from the known compat list.  There've been some others tried & work but IIRC they had higher-than-recommended heater draw.
 
WRT 5687 you missed the most critical thing about 12au7/6922 compatibility, pin-out:
12au7:http://www.scottbecker.net/tube/sheets/093/1/12AU7A.pdf
5687:http://www.r-type.org/pdfs/5687.pdf

 

[Forte]

Both 12AT7 and 12AX7 were tried early on and neither could be made to work.  Have copied Alex's explanation below.
I can vouch for the 6N1P and 12BH7A, both worth having(especially the 12BH7A).  6N23P-EV and 6N6P also work although IIRC the 6N6P is beyond what the Heater Supply was designed for and you need to change L1H & L2H to cope.  Heat sinking ICH was also recommended.
 
 
Quote:

Quote:

Originally Posted by nux /img/forum/go_quote.gif Can anyone confirm whether 12AT7 tubes will work with this? I have been buying up some 12au7, 12bh7a and 12at7 tubes in preparation for building this amp!

Tubes like 12at7 and 12ax7 will probably not work. Their operating points are just outside of what the tube servo can do. This is because neither of them is happy at 80V. However, as several have noted, their gain is too high anyway and your volume pot would become useless.

Try some 6N1Ps. They'll be more fun.

Gents, one reason for the choice of 12au7 as the design center tube is because, if all else fails, there are several sources of current production 12au7s. Thus, you won't have the problem of NOS stock getting depleted making the amp into a paperweight.

Additionally, 6N1Ps, 6922s, and 12BH7s are also in current production. Just remember me when you're rolling tubes.

 

 

[Mullet]

I was specifically asking about the 12AV7 & 12AY7, which are both in the 40 mu mid gain category. I realize that the other variants have too much gain. I suppose if they have the same pin outs they would be similar to using a 6922 or even 4BQ7/4BZ7. The other thing to keep in mind is having enough heater voltage I guess. Is 80v enough? I'm assuming that since no one has commented yet on these particular tubes then they probably don't work.

 

[Mullet]

I'm back. Searched the thread. I didn't find any info on whether 5670 or 2C51 works as a 6v drop in replacement. According to the tubes compatibility sheet that cfcubed posted, it appears that they are a possibility. The only caveat is that they haven't been tested. I just won an RCA 5670 for a buck, so I guess I'll be the first to find out and post my findings.

 

[cfcubed]

Quote:

I'm back. Searched the thread. I didn't find any info on whether 5670 or 2C51 works as a 6v drop in replacement. According to the tubes compatibility sheet that cfcubed posted, it appears that they are a possibility. The only caveat is that they haven't been tested. I just won an RCA 5670 for a buck, so I guess I'll be the first to find out and post my findings.

If you look closely the 5670 row is white which means not evaluated.  Light green (hard to see diff w/white) means could possibly work but not tested.
As said for 5687, most important thing to check is the pin-out & the 5670's incompatible w/CTH: http://www.sphere.bc.ca/test/tubes16/ge5670-2c51.pdf
Would be careful straying from "core/main" CTH tube list, dark green rows or tubes reported to work.  It's conceivable that trying a sufficiently wrong tube could blow the unit.

 

[Mullet]

D'oh... looks like I'll be tossing this one back up on the bay or in the trash bin. Hate to do that to such a lovely tube. Guess I'll be sticking to the standard CTH tubes

 

[civilmonkey]

I seached this threat but it seems no one has posted about an English 1960's vintage 6DJ8 Brimar Tube.  I pickled up this tube on ebay for a reasonable price, and it's my current favorite.  My second favorite would be the Sylvania long grey plates I have.  I haven't heard Telefunken smooth plates or Bugle Boys.  The Brimar seems to do really nice with classical.

 

[BK_856er]

FYI the well-liked SoniCap GenII caps are no longer being produced.  The 200V version is out of stock from the manufacturer, but might be available elsewhere until inventory is depleted.  I got the somewhat larger 400V instead - looks like it will fit.  Several new versions will be released in the future according to Soniccraft.
 
BK
 
 

 

[Mullet]

From what I've heard about Brimar their sound is similar to other British tube manufacturers in that the sound is very warm, rich, and tube-like. A friend of mine has the Brimar CV4003 running in an RSA Raptor. He loves the Brimar sound especially with female vocals. I reckon an American equivalent would be RCA. The black plate 5963 comes to mind. With my Senn HD650s I find it to be tad bit too meaty sounding. With my Beyer DT880s I find it just about right with rock and roll. I just picked up a used Mullard 12AU7 long plate on fleabay and while its a nice tube with the female vox, but it's no Siemens. More on that later. The Bugleboys are nice especially with the empahsized mids and decent highs. They have this punchyness to them. All Amperex do.

I have both the tele smooth plates and ribbed plates and right now I'm favoring the ribbed plates. Perhaps, it's because I want clarity and detail over everything else. The smooth plates seem warmer but still have nice detail. The only Sylvania I've tried that I liked and stay with for a bit was the gold brand 5814A.

I'm going to have to with Siemens as my all around favorite brand for 12AU7/6DJ8 tubes. They are like the Mercedes Benz of tubes -- smooth, tight bass, well-defined, nice high end extension -- just really classy tubes. The thing about tubes is that one sounds awesome with one set of headphones and ok with another. I tend to go with 6v tubes for my AKGK701s because they have more gain than the 12AU7. I find the 6DJ8 tubes to be a bit too much with my Senns.

 

[civilmonkey]

 
Quote:

I'm going to have to with Siemens as my all around favorite brand for 12AU7/6DJ8 tubes. They are like the Mercedes Benz of tubes -- smooth, tight bass, well-defined, nice high end extension -- just really classy tubes. The thing about tubes is that one sounds awesome with one set of headphones and ok with another.

 
Hi Mullet, All I know about the Siemens tube I have is that is says E82CC. It's made in Germany, has an 8 stamped into the bottom and you can make out D73 on the rear side of the tube. Do you happen to know what kind of Siemens it is?  I place it as a 3rd for my enjoyment, with the 6dj8 Brimar as 1, 12au7 RCA grey plates as 2 and this siemens 12au7 tube below as 3rd.  This is for my DT880's, so maybe the 6dj8 is a nice match for it.
 

 

[Mullet]

The E82CC the equivalent of a ECC802S, which is a premium grade version of the ECC82. It's considered a pretty rare tube. Yours looks to be the triple mica version, which is said to be better than the double mica version. It's said that yours has the best high end extension and clarity. If you're not into that tube then it's most likely the Siemens sound isn't for you. Perhaps, it's just not matching up with your particular set up and might be coming off as too lean. I would tend to think that Telefunken isn't going to work for you as well. Both German tube companies sound is described as lean and analytical in nature. I tend to like my Siemens better with my Senn HD650s above everything else ie AKG K701s and Beyer DT880 320ohms. These are the Siemens tubes I have and the order that I like them in... ECC82 chrome/silver plates, CCa, ECC802S, PCC88. If you don't want the tube I'll gladly take it off your hands.  
 
Is your RCA the clear top version? I have the Conn branded clear top 12AU7 and love it. Reminds me a bit like the Siemens (detail), but with a tad bit mid warmth. I also have the RCA 6FQ7/6CG7 clear top and it's a peach as well. I'd recommend either/or and they are both on the less expensive end of things tube wise.

 

[civilmonkey]

Thanks for the detail Mullet.  I'm definitly not upto speed on which tubes are which, I basically read a bit, and if something seems like others have enjoyed it, look for a good deal on ebay.  The Siemens tude I have I paid 25 USD I think.  Let me listen to it a few more times before I give it up   Is there an online resource with details like you describe, or is it knowledge one collects over time reading various sources (would be my guess).
 
Yes, the RCA Cleartop is a Conn branded 12AU7 (red text).  The RCA Long Grey Plates (I think!....) are Conn branded in green text, and those are my #2 fav for now.  The Cleartops and Grey Plate tubes are pretty similar for sure.
Quote:

 
Is your RCA the clear top version? I have the Conn branded clear top 12AU7 and love it. Reminds me a bit like the Siemens (detail), but with a tad bit mid warmth. I also have the RCA 6FQ7/6CG7 clear top and it's a peach as well. I'd recommend either/or and they are both on the less expensive end of things tube wise.

 

 

[cfcubed]

Quote:

Is there an online resource with details like you describe, or is it knowledge one collects over time reading various sources (would be my guess).

I linked to a few in my "CTH tube info" link in my sig under "Lots of tube preference/synergy opinion here on head-fi and elsewhere like".
 
My own likes run close to what I'm hearing here....  E.g. I prefer a bit warmer/bassy tube (like Amperex or rolled top-end ala Mullard) w/DT880/K701 and the Siemens ECC82 (or maybe clear-tops) w/my HD600s.