[wilsynet]

So I don't hijack this thread, I posted my response regarding the upgrade to the Isabella here:

http://www.audiocircle.com/index.php?topic=62974.0

[Eadron]

Hi,

went back to Steve's Amperexes after the stock JJs and..they are absolutely fantastic NOS tubes  (I laugh at myself)..but I won't throw the JJs away anyway..you got to have some good spare tooobes around  ..

jouni

[texendo]

These tubes look to be promising, but from my very limited knowledge on the subject, they likely won't work with the Isabella.  Would someone with more knowledge illuminate please?

http://www.techtubevalves.com/valves/index.php

[wilsynet]

The Isabella accepts the following tube types: 6922/E88CC, 6DJ8/ECC88, 7308/E188CC, 7DJ8/PCC88, 6N23, 6H23 and 6N11.

But TechTube Valves is (for now) making the ECC83/E813CC, ECC82/E812CC and the ECC81/E811CC, none of which are accepted by the Isabella.

A couple of more good places to go for appropriate tubes are:

Vintage Tube Services
http://www.vintagetubeservices.com/page18a.html
Look for the section titled 6DJ8, 6922, 7308.

Brent Jesse
http://www.audiotubes.com/6dj8.htm
Scroll down quite a bit and you'll see his stock list.

Vintage Tube Services has a stellar reputation, but he doesn't open up shop again until Jan 20, so I decided to go with Brent Jesse based on Jim's recommendation.  I'd rather deal with a known quantity than roll the dice with EBay.  Running into disreputable sellers, and not having my own test equipment, you know, the anxiety just isn't worth it.

As I understand, the Siemens CCa, while magical, it's tough to find a great pair and there are a number of them out there that turn microphonic later.  I just ordered a pair Siemens E188CC (ultra premium 6DJ8/7308).  While the Siemens E188C is perhaps not quite as magical, it still reputedly offers much of the character and performance of the CCa, and it's easier to find a good pair at (cough) a reasonable price.

http://forum.audiogon.com/cgi-bin/fr.pl?ymisc&1191291379&read&keyw&zzcca

[wilsynet]

Vacuum tubes fell out of the mainstream long ago so it's not surprising that I know virtually nothing about their care, in particular, how they should be handled.  There's plenty of postings that talk about how cotton gloves are essential and that you don't want to get fingerprints on the tubes because they'll cause hotspots, and there's even someone selling a purpose built "tube glove" here:

http://www.tweakshop.com/TubeGlove.html

I wrote Brent Jesse and asked him about this.  Presumably, as a reputable dealer in tubes, he would know.  As I'm sure he would not mind me sharing his response, here it is.

"Fingerprints do not harm the tube.  Above all do not clean them, as cleaning will take off the fragile label!  If you want to keep them as clean as possible, either handle them with cottom gloves, or carefully hold them only
by the top rim (or the black plastic base in the case of octal tubes) and do not touch the label.  These NOS tubes have labels that are mostly powder with age, and rub off easily."

He further clarified regarding "hotspots":

"No, the power tubes do not get hot enough for the fingerprint to cause a hot spot.  This happens with so-called quartz light bulbs (tungsten-halogen) since they burn at a bulb temperature that is nearly 1000 degrees on the
inside surface.  The fingerprint actually blocks the light and heat and causes the glass to get super hot at that one point, which eventually will crack and fail.  Bare halogen bulbs should never be handled without gloves.

"Electronic tubes, even those with very hot envelopes like an EL34 or 6BQ5 do not get nearly as hot on the glass as a quartz lamp.  It is still a good idea to keep these tubes clean, as dirt and fingerprints can get "baked on"
and become very difficult to clean.  Also, flammable material should be kept away, as the glass could become hot enough to melt plastic or cause a fire.

"Anyone who has experienced a 'hot spot' on a power tube is more likely seeing the result of incorrect bias on the tubes, and the result is thermal runaway.  The plates become super hot as the incorrect bias causes them to
draw huge amounts of plate current.  They begin to glow red hot on the sides, and if a fuse does not blow, the tube will actually start to soften the glass nearest the hot spot on the plate.  I have seen some of these tubes that suffered this fate, and the glass actually had a huge bulge on the side near the plate that had gone red-hot."

So the fingerprint thing is, according to Brent, mostly a cosmetic issue and not a premature failure issue.

[Vinnie R.]

Hi wilsynet,

Thanks for sharing this information. 

I agree with Brent - the tubes in the Isabella do not even come close to running hot enough to need to worry about "hot spots." 

I am more concerned with making sure the pins are carefully inserted into the sockets, and that the tube pins are straight, clean and free of oxidation.  Carefully rubbing the tube pins on steel wool and then cleaning them with electrical contact cleaner is a good thing to
do with old NOS tubes that have pins that are not clean and shiny. 

Best regards,

Vinnie

[Alwayswantmore]

Hi wilsynet,

Thanks for sharing this information. 

I agree with Brent - the tubes in the Isabella do not even come close to running hot enough to need to worry about "hot spots." 

I am more concerned with making sure the pins are carefully inserted into the sockets, and that the tube pins are straight, clean and free of oxidation.  Carefully rubbing the tube pins on steel wool and then cleaning them with electrical contact cleaner is a good thing to
do with old NOS tubes that have pins that are not clean and shiny. 

Best regards,

Vinnie

I played around with a couple rubber-ring tube dampeners. While I did not go to out of my way to 'touch' the tubes, my last round of testing was to place the rings high on the tubes, then 'gently' roll then off to see if the sound was better or worse. As far I tell, the tubes are cool enough you could probably touch them bare handed (not that this is recommended).

BTW: After much experimentation with brass weights, myrtle wood block isolation bases, granite bases, rubber tube rings, etc., right now I'm running my system with NOS Amperex tubes from Steve at Northlake, and both the Isabella and Sig 30.2 amp are isolated by 3" Timberland Maple bases spiked directly to the subfloor in a carpeted room. So far this is the best I've found for tone, detail, etc. Kent

Kent

[Vinnie R.]

and both the Isabella and Sig 30.2 amp are isolated by 3" Timberland Maple bases spiked directly to the subfloor in a carpeted room. So far this is the best I've found for tone, detail, etc. Kent

Hi Kent,

If you get the chance, can you start a new thread in the RWA forum about these Timberland Maple bases (with some pics if possible, and links).  I'm curious to learn more and I'm sure there are others here who are as well. 

There are many times when I am changing equipment around for testing, evaluation, etc. and it is easier to just keep things on the floor when doing this (instead of trying to moving equipment in and out of a rack), so a good quality base sounds attractive for this!

Thanks!

Vinnie

[Fork]

I had a conversation this week with Vinnie about Isabella tubes and I'll pass on some info about the basics.

He says the measurement of tubes is not entirely straightforward.  Different testing machines, tubes measured under different conditions and other uncontrollable factors can give different readings for the same tube.

Most tubes I've seen online give two kinds of measurements (like 17.0/16.5 or 640/720).  Since the Isabella doesn't use balanced outputs you can simply add the two numbers for each tube and compare them.  A variance of 5% or less is a good match.

I read that CCa tubes have a tendency to become microphonic and sure enough after 2 weeks of using an expensive set, one developed a hum; I was fortunate the seller was willing to replace them.

Most of these tubes are rated for 8-10,000 hrs.  Vinnie says the Isabella is especially gentle on tubes, so you can expect your tubes might last longer than rated.  Be careful when rolling tubes to make sure the pins are lined up well and not to press too hard, to avoid bending a socket contact.  Vinnie will measure tubes for his customers, if you want to send them to him.

[Vinnie R.]

Hi Fork,

Thanks for your post.

Yes - I prefer to measure the tubes and match them inside the Isabella by testing them on the bench here.  For example, feeding a 1Vrms input, at full volume I expect 1Vrms output at the low gain setting (0dB) and 4Vrms output for the high gain setting (12dB).  If the tubes are matched within a dB, that is very good!

This way, they are being tested under the conditions set by the Isabella (not some tube tester) and I know for sure how the tubes are behaving in this circuit.

All the best,

Vinnie

[Eadron]

Hi all,

it's about time to try different tubes in Isabella. The following are coming (I hope before X-mas) aa:

'64 is the year..I'll post my impressions as soon as I can.

jouni

[Vinnie R.]

Hi Eadron,

Thanks for keeping us posted.  I recently acquired quite a few different tubes to try as well - looking forward to getting some free time to try them all out and post impressions!

Happy Holidays!

Vinnie

[Earman]

Anyone ever try tube dampers in an Isabella? If so, which dampers with what specific tubes? And was there any noticeable effect?

[Vinnie R.]

Anyone ever try tube dampers in an Isabella? If so, which dampers with what specific tubes? And was there any noticeable effect?

It's a tight fit to put them on the tubes of the Isabella.  I listened to a few (forgot the brands) and did not hear much effect.   

BTW, this thread about tube rolling will be seeing more action in the near future 

 

[texendo]

Anyone ever try tube dampers in an Isabella? If so, which dampers with what specific tubes? And was there any noticeable effect?

I use the Herbie's Tube Dampers.  Yes, they are a very tight fit, but they work.  The difference isn't night and day, but they tighten up the image a bit.  I wouldn't even necessarily say they make things sound better, but definitely different, and I almost always have them "on."  I suppose you loose some of the "air"(?) in exchange for more "focus."

On another note, I recently tried some new tubes that some of you out there may want to give a shot.  I got them from cryoset.com (cryogenically treated) for about $80.  They're the New Sensor Genalex Gold Lion E88CC's. 

I've spent more money than I'd like to admit chasing after various NOS offerings.  There is definitely a "magical" quality to their sound, and I understand why people pay top dollar for them.  Unfortunately, they're half a decade old, and no pair I ever used really could offer the detail of the MUCH lower priced tubes that come stock with the Isabellla.  I'm not saying none exist, but good luck finding them anymore.  I finally switched back to the stock pair over a year ago and hadn't looked back.  Recently, I found out about these new issue tubes that are made in Russia, supposedly on some of the old machines that made some of the golden oldies of yesteryear.  The pins are gold and actually look like it.  The sound IMHO is easily worth the asking price and then some.  They even seem to have more gain than any tube I've used before.  If the treasure hunt for golden era tubes gives you pleasure, ignore this.  If you wanna just get some exceptional tubes so you can listen to your bad ass Red Wine rig, I very highly recommend the New Sensor Genalex (cryogenically treated from cryoset.com are still cheaper than off the company's website due to early dealer pricing).

[kitten]

Thanks for your research and the tip... little in the way of downside risk at that price so order made...

If the treasure hunt for golden era tubes gives you pleasure

This is not me at all...

If you wanna just get some exceptional tubes so you can listen to your bad ass Red Wine rig,

Yep, that's me! 

[texendo]

kitten,

Please let us know what you think about the Genalex tubes...

[Major Roadrash]

The Isabella/DAC is the first piece of tube gear I've owned and I haven't used anything other than the stock JJ tubes before now.  Based Texendo's recommendation, I ordered a pair of the Gold Lion E88CC/6922s from Cryoset.  They arrived today and I wanted to post my impressions after the first hour of listening.

The Gold Lions have got to be the best "bang for the buck" going.  For less than $100 I've got more detail, fatter bass, more separation around instruments and a more three dimensional presentation.  All this translates into smoother, more realistic sound.  Lyrics are easier to understand, acoustic guitars sound more like individual strings being strummed and plucked, drums sound fuller.  It's an impressive upgrade.

So...a shout out to Texendo, thanks for posting about these (and thanks again for the Divas).

Best Regards,
Dan in Ottawa.

[texendo]

Hey Dan in Ottawa, I'm glad to hear it wasn't just me : )  It's good to hear the Divas found a good home too...

[Vinnie R.]

If you wanna just get some exceptional tubes so you can listen to your bad ass Red Wine rig, I very highly recommend the New Sensor Genalex (cryogenically treated from cryoset.com are still cheaper than off the company's website due to early dealer pricing).

Hi Texendo and Dan,

Thanks for posting your feedback on these - I want to order a pair today.  But why can't I find them on their webpage?  Any direct link to these tubes?  Thanks

Cheers!

Vinnie