Tube Rolling for Bellari HA540

I'm using the Bellari with AKG Q701 and am testing a few different tubes currently.  Really nice amp.  I'll post my opinion after a few more days of tube swapping.

I used the stock Ruby 12AX7 for a while but the other tubes I'm trying are not 12AX7 because this is way more gain than is needed for this amp.  Instead, I'm using a Sylvania triple-mica 5751, Siemens 12AT7, and an Amperex PQ (Holland) 7062.

I know user Terja posted some helpful feedback on tubes for this amp previously.  I think he settled on Tung-Sol 12AT7 as his favorite.

This post turned out a bit long, but I hope it is helpful to future HA540 owners

Interesting that this has popped up recently, as I purchased an HA540 right about the time the thread was started.

First, I read every comment and post on the Internet about this amp (and tubes for it), which is not hard, as there is not that much.  Bellari is made by Rolls, who make professional audio equipment, and so they don't publicize their gear through either Audiophile or Headphone circles.   So, the amp has received very little attention, relative to say, Woo Audio or Bottlehead.  However, I did notice that all the reviews were positive.   Unfortunately, no one has compared the amp to any other amps - one review mentioned that he thought the amp sounded comparable to ones "costing several times as much", but never gave specifics.  I was looking for something that was better than the Cmoy, and used tubes, but not as expensive as a Bottlehead or Woo, and the HA540 seems to be the only good choice that fits.

Second, there is a lot of gibberish on the Internet about using other tubes to substitute for 12AX7 tubes.   There is one famous old article on another site promoting that idea, but which has been called into question by more than one tube expert.   And, I have yet to hear one comment about using different tubes by anyone who knows anything about electrical engineering.   In short, I think it is a bad idea, and an especially pointless one since there are more 12AX7 tubes available than any other type.

Terja mentioned using a different type in order to get "less gain", but other comments of his seemed to indicate that he was using the higher gain input (which confusing is called "low").  So, he could probably get the same result by just using the input marked "high" (which is what I use).

Anyway, after some researching, I tried two new production tubes:

- JJ 12AX7 ECC803S Gold-Pin cryo-treated from cryoset.com

- Tung-Sol 12AX7 ECC803S Gold-Pin cryo-treated from cryoset.com

In both cases, I chose that model not for anything about gold pins, but because they also have been pre-selected by the manufacturer to be higher quality.

I did not compare cryo-treated to non-cryo, but I did read several threads about it, and the differences described by several people seemed not to be imaginary.   The difference in price is minor, and cryoset.com is a good supplier for tubes in general, so I just went with those.  The idea was to give new production the best possible trial.

The result with the new production tubes (with at least 20 or more hours of burn-in on each), was that I found the supplied tube to have some "glare" or "screech".   The JJ was definitely better in that regard, and in various other qualities (I have not yet done a definitive comparison between any two tubes, it is mostly my subjective impression so far - although I do have a set of tracks that I play each time I change tubes).   I later found the Tung-Sol to be an improvement over the JJ.

However, I still found all three new production tubes to have some "glare" (I am using a Shure SRH-1840, so any screechy aspect is very apparement).   So, I did more research on vintage tubes.  A great site is:

http://www.audiotubes.com/12ax7.htm

(His prices - even for the lower cost items - are somewhat higher than what you find on ebay from reliable suppliers, but clearly you get premium service and carefully tested and selected tubes from him.  But, the site is also a great resource for information very useful in investigating tubes you find elsewhere.)

The four vintage tubes that are constantly mentioned in a variety of threads on tubes are:  Telefunken (made in Berlin), "Amperex" (made by Philips in Heerlen, Holland), Mullard (made in Blackburn, Great Britain), and RCA/Sylvania/G.E. (made in USA).  The USA ones always have the qualifier "great value for the low price" or "surprisingly good in guitar amps", and so I decided to try one of each of the other three European tubes - because - the HA540 only needs one tube and so price is not as much of an issue as with amps that need four, six or eight tubes.  (But I should point out that the best reviewed USA tube - the RCA "black plates" - costs no more than the above new production tubes, and might be better than any of them.)

The first vintage tube I tried was an Amperex 1970 12AX7A.  The sound is definitely a step up from the new production tubes, and is without that glare.  It has excellent bass, and generally a wide even bandwidth from low to high.

I then tried a Siemens 1961 OEM tube made in Munich, West Germany for "Capehart" - the first high end audio company in the USA (probably for their record player which used six 12AX7 tubes).    The web site linked above recommends several "equal but cheaper" subsitutions, including Siemens as sounding very close and similar to the famous and pricey Telefunkens.   And I have found the Siemens to be another step up over the Amperex, due to its very superior sounstaging and imaging.   The Shure SRH-1840s are unusually good in that respect, and easily reproduced the exceptional "3D" sound of the Siemens.   You can hear small movements of sound in all three directions, and instruments that produce a sound from many points do have a more three-dimensional sound.   It's subtle and I think fragile - for example, a cheap headphone extension cord might be enough to make it vanish.

I also ordered a 1963 Mullard made in Blackburn in Great Britain, but that has not arrived yet (and it will probably be a week before I can add my impressions of that to this post or this thread).

When a component provides something that is missing otherwise, that is very compelling to me, so at this point, I am inclined to ratify the plurality of tube fans who feel that vintage West German tubes (usually as "Telefunken") provide the best possible sound quality.

Great feedback, kstuart.

Regarding your comment:

I have read really good things about the "Project Sunrise II" amp on the rockgrotto forum (some very long threads there covering evolution of version I and the current version II of this amp)  and some foreign language sites as well, so I would add that to your list.

I've got one on order now and will likely be returning the Bellari to Amazon after getting a chance to compare the two.  The Bellari sounds fine but IMO has poor build quality and is lacking in features for the price when compared to the Sunrise amp.  The Sunrise costs a bit less at $250 built, has a 2 year warranty, is made in the USA also, and has so many additional features as well as better components and design.  The only feature it is lacking compared to the Bellari is the low inputs but I don't use my phone as my source so that's a non-issue to me.   High level summary of the Sunrise here: http://ep.yimg.com/ca/I/yhst-56214408072058_2213_1918037 .  See the rockgrotto forum or the garage1217.com site for more info.

Regarding your question about using different tube types, the Sunrise is designed by electrical engineers and they make it clear that it is intended to support many types of tubes (you can set the bias yourself easily using onboard LED's without a multimeter and even pick 6v or 12v, plus do some other easy tweaks using jumpers).  I think the Bellari is also fine with different tubes within reason but more limited than the Sunrise of course. My favorite in the Bellari so far is the Amperex PQ 7062 over the 12AX7, likely for the same SQ reasons you prefer the German/Telefunken 12AX7's.

Quote:

Originally Posted by Passingthrough 

The Bellari sounds fine but IMO has poor build quality and is lacking in features for the price when compared to the Sunrise amp.

I'm not sure what "features" you are referring to on the Sunrise, and I'm not sure what "poor build quality" you are referring to with regards to the Bellari (mine seems quite solid).

The Sunrise is one of many hobbyist DIY amps that I already noticed previously - there are plenty more in the DIY Forum on this site.   The "Garage" ebay guy is simply someone who assembles it for you, and so the "two year warranty" is depedent on the guy not vanishing before then.

Another similar preassembled DIY tube headphone amp with similar "buzz" is the Nixie, built by a guy in Germany for $189:

www.ebay.com/itm/280879125546

Rolls is a professional studio equipment company, and their products are offered by various pro sound companies. (In fact, if you contact Pro Audio Star in NY about the HA540, you can haggle in the usual NY musicians'supply fashion, and get a new one below $250.)

Previous Bellari tube products - their phono preamps - have gotten excellent reviews from Stereophile and audiophiles at the Steve Hoffman forum.  You can get a better sense of their product line by scrolling through:

http://www.rolls.com/pdf/catalog.pdf

This sounds suspiciously like "the enthusiasm of those guys in that Forum is compelling".  How exactly do we know that the "design" is better ??

Whatever sounds better is better.

Any one of the amps mentioned in this thread could have better sound than the others.   If you do compare two of them at the same time, that would be great to hear about.

First, I should state that for me also SQ wins the day.  If the Bellari sounds better to me then that one will stay, even though I like the feature set of the Sunrise better.  

As far as "better design" I should have clarified that I meant the design of the unit generally, not specifically that it was a "better" audio circuit. Only blind AB testing will tell that, and even then only for the specific listener possibly.  The design approach of making it easily user configurable, without even needing special tools or removing the case cover, and the support for a wider range of tubes makes it a better design in my opinion, or better put, better for my intended use.

I did not want to sound like a fanboy (after all, I don't even have the thing yet -- I may end up thinking it is awful) so I did not list the additional features but since you asked, here are the ones that mattered to me:

• Line out for preamp use
• Jumper to bypass input caps (e.g. if not using volume pot) to avoid coloration there
• Variable output resistance, selectable from 10 to 68ohm
• Easy to set bias via LED indicators using onboard Bourns trimmers  
• Larger Bourns machined aluminum potentiometer  (trivial, but I find this matters to me)
• Dedicated heater power supply (I'm not home now but I don't think the Bellari has this)
• 6V or 12V voltage is user selectable (for even more tube options)

I have been enjoying my Bellari HA 540 amp for about six months now and would like to add my observations to the previous posts. First, I have to take issue with the "poor build quality" statement: IMHO the Bellari is very well made,  particularly for a tube amp in it's price range (I paid $250 for mine including shipping). The quality is apparent once you listen to it. This amp is dead-quiet and compares quite favorably to many higher priced competitors. I originally became interested in the HA 540 because of the rave reviews given to the Bellari tube phono stage by Stereophile and other respected sources, especially because that product has a well-regarded headphone output. Several prominent audio dealers also highly recommend the Bellari, these guys sell much more expensive equipment but love the HA 540's sq (Music Direct for example). Add to that the versatility of this amp with it's outputs and inputs and it seemed well worth a try - I have never regretted this purchase. I use this amp with my Grado PS 500, AKG Q701 and Sennheiser HD 598 phones (it is excellent with all 3, but the PS 500 has become my personal favorite). Which brings me to the tube rolling issue. The Bellari is an OTL design which means the particular tube you use makes all the difference as to what you hear. Since it uses the 12ax7 you can try some of the most sought-after tubes out there, and like kstuart said that includes Telefunken, Mullard, Amperex, Siemens, Mazda and RCA, Sylvania & GE as well as current production (which are way inferior to vintage). You can also use the 5751 and 7025 which are also 12ax7 variants. I have had great results with a nos Sylvania 7025 (amazing with this amp) and I am currently breaking in a 1956 Mazda triple mica 5751 which is very rare but has about 30% less gain than a standard 12ax7 and therefore gives you more headroom with low impedence headphones like my Grado PS 500. By the way, kstuart is correct about the "high" input being the one with less gain-I almost never use the "low" but that one will power those 600 ohm cans with ease! I also would recommend the RCA blackplates, both regular 12ax7 & 5751 versions. If you get a chance don't be afraid to try that Sylvania 7025 (which is just a low-noise 12ax7 which really excels in hi-fi applications). Who you buy nos tubes from is key - I have had good experience with Brent at audiotubes.com for the really rare tubes as kstuart linked, and amplifiedparts.com has the Sylvania 7025 nos for about $35 (as opposed to the misrepresented used tubes you often find on ebay). 

Thanks guys, it is nice to see this thread - enjoyed your input and hope the discussion continues! 

First, if your unit has those flaws (none of those on mine), then it is definitely poor quality control, and if you end up preferring the Bellari, you should ask for an exchange.

Quote:

Originally Posted by Passingthrough 

• Dedicated heater power supply (I'm not home now but I don't think the Bellari has this

Hmm - that is the sort of design feature that you can only judge if you have two copies, one with that feature and one without.  Some of these things, (like "Class A") have advantages and disadvantages.  The Bellari claims:

and

Do any of the other amps in the thread have those ?   I have no idea.   They only affect the design and the ultimate sound quality.

In contrast, user features, like Sat Nav and Power Windows (as opposed to "dual overhead cam shafts") have direct differences in the user experience, whereas design features are only assessed in terms of sound quality (or "driving performance" in terms of my analogy).

Quote:

That is somewhat troubling.  Why?  A year or two ago, I tried all the various Windows music players and compared them for sound quality.   One obscure audiophile player, includes the ability to change three parameters - with no explanation of what they did, but I'm pretty sure that an explanation wouldn't help, as the concept is to allow the user to change the quality of the sound is a near infinite fashion.  Of course, you could spend thousands of hours comparing the sound quality of combinations of three parameters !  Infinite choice and no choice are the same, ulitmately.   Similarly, I don't want to have a large number of tube choices - it just makes things more difficult.  So, the fact that the Bellari limits all the choices and configuration to solely one choice of one 12AX7 tube, makes it much easier to get a final preferred setup.

In contrast, the whole situation of a constantly evolving design, with public input, and a variety of user adjustable internal electrical parameters is fine, but it is ultimately a DIY project, where the tinkering is a large part of the hobby.   Certainly nothing wrong with that.

12AX7 alone has many choices, but fortunately they are very well defined.  I received the Mullard today, and so far I can tell that it will be a close choice between it and the Siemens.  But I wait for it to be burned-in before making a real assessment.   Brent of audiotubes.com comments:

Hmm, a lack of options is a feature to some I guess.  As for me, if I happen upon an interesting tube someday I'd rather have the option to give it a listen than to not have that option.  

In any case, the Bellari is not limited to the 12AX7 -- I and others have reported that we prefer other tube types on it.  For me the 12AX7 was a tiny bit more bloated and unrefined than some others I tried.  For other listeners 12AX7 will sound best with their system and/or ears I'm sure.

It's funny that you state that having a dedicated heater power supply is "a sort of design feature" whereas having over 200 volts plate voltage as advertised by Bellari "affects the design and ultimate sound quality".   Help educate me on this distinction -- does SQ go up proportionally with plate voltage so the amp with the most sounds the best, or is there just a big drop-off in sound quality if an amp has anything less than 200 plate voltage?

I'll try to let my ears decide about SQ when the Sunrise arrives.  It will be interesting to me to see if I can tell a difference between the amps in a blind test when using the same tube.

Quote:

Originally Posted by Passingthrough 

It's funny that you state that having a dedicated heater power supply is "a sort of design feature" whereas having over 200 volts plate voltage as advertised by Bellari "affects the design and ultimate sound quality".   Help educate me on this distinction -- does SQ go up proportionally with plate voltage so the amp with the most sounds the best, or is there just a big drop-off in sound quality if an amp has anything less than 200 plate voltage?

Lack of communication on my part - I was not making a difference between those, as I said in the car analogy, both of those "design features are only assessed in terms of sound quality", with emphasis on "assessed" - we can only assess whether those things actually make a difference by listening.

Kstuart, thanks for the clarification -- we are on the same page there.

The Sunrise will be shipping soon and I will post back my thoughts then.  I did go ahead and email the company that makes it to ask about who does what (to confirm he's not just some guy who builds it as you had thought) and I also asked about which of the adjustable/optimizable elements were most important in his experience.  He gave a thoughtful reply:

I'll try to get back with my thoughts on the Sunrise and how it may compare to the Bellari later, which I should probably put on a different post.

And an update on tube rolling on the Bellari since that was the original topic here!  I have been listening to a Siemens 12AT7 with date code 1960 (this one is marked "selected tube" but that may not really matter 52 years later) and it is really nice and does everything right.  

Thanks for the post with the info from the designer.

To clarify, I am not saying that adjustable parameters are bad (or good).

However for human beings, who have limited time, an infinite number of adjustable parameters IS bad, because we can never finish testing all the possibilities.   So, between zero and infinite, what is the point where it is too many ?   I think not very far beyond zero, frankly.

Take the Bellari - you have only one - changing the tube.   But, 12AX7 alone has an astronomical possibilities - just comparing Siemens to Telefunken to Mullard to Amperex to JJ to Tung-Sol is a project of many hours.   And then if you start with other tube types, you have to compare Siemens 12AX7 to 12AT7 to Siemens 5751 and on and on.

These differences are already subtle, and in fact the "Objective" guys think we are imagining the differences.

So, this is already comparing 18 different setups (6 makes and 3 types of each make) and we have left off many others.

If you add to that "the possibility of using many other tube types", you are already getting beyond what audio memory    Now add varying the resistance times 18 times other tube types, and it seems already beyond reasonable possibility.

For someone doing this full-time - namely a designer - it would seem much more reasonable, since he is dealing with all this on a daily basis.

Of course, all this is optional, so it is fine from that perspective.... so I am just pointing out one aspect.

I do get the less is more idea.  But I would argue that adjustable parameters are in fact good in any system where all the variables cannot be controlled by the designer (in this case there are quite a few: headphone, source, tube, ears), provided that having them does not itself result in a net sacrifice in sound quality.   

I think your last point about it being optional how far one wants to go in trying all the possible configurations nails it:

Like you, I would never try test all combos or go actively hunting down all tube types to try.  That way lies madness.  But it seems like a no-brainer to dial in a super easy change like output resistance for whatever headphone is being used since that may have an impact on SQ and just takes a minute, so I'm sure I would try that one for each of my headphones.  And I'll surely try whatever tubes I currently have that will work, just like I've been doing with the Bellari.  And to bias my amp properly for tube performance and longevity since that's just turning a dial until a LED goes out.

For others who might actually enjoy trying every parameter combination with every tube type/mfg/year/etc (imperfectly given audio memory as you noted) to get the "best" setup, this would turn the amp (arguably any tube amp) into a hobby as well, at least for a while.  There are worse hobbies, but I personally don't plan to go down that rabbit hole.

I posted a review and comparison of the Sunrise II and HA540 as a new thread here:

http://www.head-fi.org/t/620712/review-comparison-project-sunrise-ii-and-bellari-ha540

Congratulations.   Using the "fear of having bought the wrong product" was a very effective retaliation against Bellari for sending you a lemon.

By doing that in this thread, you entirely destroyed any likelihood of people trading information on the best tubes for the HA540, thus insuring that it usually sounds worse than it could.

Awesome job !