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2A3 Options

198.233.141.11

Posted on December 21, 2016 at 10:23:30
maxhifi
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Posts: 498
Location: Alberta, Canada
Joined: August 4, 2004
I've posted about my single ended triode amplifier in the past. It's got a Mullard EF37A driving a JJ 2A3-40, with a 6CA4 rectifier and a CLC power supply.

Output transformers are Sowter SP-02, and power transformer is a re purposed RCA Victor console stereo transformer.

I shuffled this amp into and out of my system over the years, because although it sounded good with some types of music I could never get good synergy with any speakers. It wasn't powerful enough for my Tannoys, and I never really thought it got the best from my La Scalas either.

I recently rebuilt some Sansui SP-3005 speakers into brand new cabinets, and decided just to try the SET amplifier. The synergy is unbelievable... finally I "get" what all the fuss is about.

Just for some fun, anyone have suggestions about another kind of 2A3 besides the JJs I could use? Seems like a pretty easy Christmas gift to buy myself, and I wouldn't mind having some spare tubes now that I know this amplifier will finally get some miles on it.

 

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RE: 2A3 Options, posted on December 21, 2016 at 12:45:52
tube Tom
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Posts: 475
Location: Las Vegas
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I am using cryoed Valve Art 2A3 in mine & like the sound. That is all I have though. Think I'm going to look for some more 2A3 myself.

 

RE: 2A3 Options, posted on December 21, 2016 at 13:12:57
maxhifi
Audiophile

Posts: 498
Location: Alberta, Canada
Joined: August 4, 2004
Valve Art 2A3s are what I had when I first built the amp... the JJs 2A3-40s are a huge improvement, I definitely don't want the old Valve Art tubes back.

 

RE: 2A3 Options, posted on December 21, 2016 at 15:05:32
drlowmu
Manufacturer

Posts: 9548
Location: East of Kansas City
Joined: January 10, 2005
Hi,

I think there is possibly only one "other" 2A3 to own, and that is the EML, but in your amp's implementation, I think the differences will really not be worth the expense.

The JJ-2A3-40 is the best choice in new, available 2A3s. All the Chinese stuff is junk, and due to their markedly inferior metallurgy, all Chinese 2A3s will turn to junk in short order.

If you want to treat yourself to something good for Christmas, I will help you re-design your B+ filter to the Finals.

(1) Your choke is likely 10 HY and 100 Ohms, needs to be no more than 20 Ohms, and

(2) never a 'C" input filter as implemented, a second serious design error.

(3) Needs to have chokes under 11 Ohms and L1/C1/L2/C2 as the topology to the 2A3 Finals, so you can hear a 2A3 as it should be heard !!

I can refer you to discriminating music listeners, who I've helped to make such changes, for their testimony...and...what they heard afterwards, if you need re-assurance.

Contact me by Forum email, and I will design it for you - gratis, on an amateur basis. Easy to make big sonic gains this way, and the amp, afterwards, will likely play your Tannoys with gusto and verve!

Jeff Medwin

Kyle, no caps, thanks.

 

RE: 2A3 Options, posted on December 22, 2016 at 08:50:17
sony6060
Audiophile

Posts: 620
Location: SE MI
Joined: August 8, 2014
I agree with the Doc. He has more experience than most.
I use only choke input power supplies and not higher than about 20-25 ohm choke resistance. I only use paper/oil caps for filtering. New Obbligato capacitors are good & cheap.

 

RE: 2A3 Options, posted on December 22, 2016 at 11:15:21
maxhifi
Audiophile

Posts: 498
Location: Alberta, Canada
Joined: August 4, 2004
Are those Obbligato filter capacitors motor run caps which have been painted, or is there something else special about them?

They look exactly like the capacitors usually connected to 4 pole single phase motors, but with a nice paint job and a higher price.

 

RE: 2A3 Options, posted on December 22, 2016 at 12:19:49
91derlust
Audiophile

Posts: 401
Joined: December 25, 2014
As far as I can tell, there are no Obbligato paper/oil capacitors, only metallised film in oil. The only new (partial) PIO capacitors that I could see myself trying for filtering and cathode bypass are the new Rike S-Cap 2... but it will be co$tly.

Cheers,
91



"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

RE: 2A3 Options, posted on December 22, 2016 at 12:30:02
91derlust
Audiophile

Posts: 401
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To my mind there is only one option.

If you are running 2A3s near full rated dissipation and you would like a similar but more "refined" sound than the JJ, I would suggest the EML 2A2-S.

The EML will last a good long time at near 15W dissipation. It sounds more even and resolved than the JJ; it's dynamics are not quite as great - it is not a overtly propulsive, but seems honest to me. The build quality is better than the JJ.

Cheers,
91.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

Thank you!, posted on December 22, 2016 at 12:45:55
maxhifi
Audiophile

Posts: 498
Location: Alberta, Canada
Joined: August 4, 2004
I see that the state of the world hasn't changed since I got the JJs in the first place... it's good to know I made the right choice to begin with. The EML looks like a very nice tube but is too much of a stretch cost wise for my budget and the quality of my amplifier and supporting equipment.

The JJ-2A3-40 is already by far the most expensive tubes I have ever bought, I think I will follow Jeff's advice and improve my amplifier a bit in other ways. The power supply could definitely use some upgrades.

 

Paper in Oil, posted on December 22, 2016 at 13:08:16
maxhifi
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Posts: 498
Location: Alberta, Canada
Joined: August 4, 2004
There's the rectangular USSR made paper in oils all over eBay. I got a couple of them for another project, and they tested good on a Sprague tel-ohm-mike. Did not use them yet. Dead on value and no leakage. I suspect similar construction to the old US PIOs.

If nothing else I sure prefer the appearance of paper in oil caps over electrolytics.. they're always a sign of serious quality in vintage gear.

 

15 watts dissipation, posted on December 22, 2016 at 15:16:49
drlowmu
Manufacturer

Posts: 9548
Location: East of Kansas City
Joined: January 10, 2005
Do us all a favor, and ask Jac what his favorite dissipation level is on his EML 2A3s, where it lasts long and sounds good to him.

I will be surprised if its 15 Watts plate dissipation. At such high dissipations, near the maximum dissipation rating, the 2A3 always sounds stressed there, because they are stressed, thermally stressed.

Post up here his response.


If anyone has to run the 2A3 that hard, for it to sound good, a DIYer likely has multiple problems elsewhere in his DIY gem / amp, typically in this order, power supply, wiring, layout, parts choices.

Be cool to hear Jac's response. Jeff Medwin

 

RE: Thank you!, posted on December 22, 2016 at 21:49:42
tube wrangler
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Run the JJ-2A3-40 at 11.2 watts dissipation. Ideally, this is with 255-260VDC across the tube.

Direct couple will drastically outperform cap-couple, and transformer-couple is second best. Use Lundahl.

LCLC is the only way to go with your PS. The "L's" don't have to meet critical inductance, but they DO have to be connected directly to the rectifier D.C. output.

A.C. Ripple should be looked at, but sonically, is a less-important factor in S.E. operation. The object is to get ripple as low as is practical without adversely affecting musical expression and flow.

Power for the driver tube must be as clean as possible, but once again, you don't want to compromise musical performance in order to "overkill" it-- be responsible to musical flow-- ignore numbers except where you truly need them to accomplish a certain thing.. Then, understand WHY you are doing or allowing a certain set of numbers.

The JJ-2A3-40 is capable of near-perfect performance if it is used right.

The EMLs are the same plant's more expensive variety. If an amp is set-up for either kind, it WILL NOT sound optimum on the other tube style.

I find it easy to get the SAME performance from either type-- the methods used are DIFFERENT from each other.

Decide what you're going to run, and then make the amp perfect with THAT tube ONLY. You can still run others-- if you set the amp up right, the others won't sound as good as the set-up tube, no matter what else you use.

The bottom line is that your amp can only sound as good as the man who set it up...

--Dennis---



 

2A3-S is a 28W tube, not 15W., posted on December 23, 2016 at 00:06:42
91derlust
Audiophile

Posts: 401
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It's loafing, should last a good long time, and sound pretty darn nice at 15W. If it doesn't, the recommended use and 28W rating would be misleading.

I'm well aware of how Jac likes his tubes used - I've communicated with him several times and he outlines it on the EML site. I wouldn't be suggesting it if I did not have some understanding. For example, I would not run the 17W 2A3-M at 15W... more like 10W.

Cheers,
91.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

I think that is a good idea..., posted on December 23, 2016 at 00:29:22
91derlust
Audiophile

Posts: 401
Joined: December 25, 2014
... go for it!

The JJs are nice tubes - if you don't want to spend more there is no need to consider anything else.

Consider what you read. Experiment, and trust your ears. No one has the formula for an amp that sounds ideal to all music lovers. Don't allow yourself to be harangued or herded. Keep in mind what you want to achieve - both sonically and with regard to your learning - then develop your approach.

Keep us informed of your adventures.

Cheers,
91.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

I have some for..., posted on December 23, 2016 at 01:10:45
91derlust
Audiophile

Posts: 401
Joined: December 25, 2014
screen bypass... but have not seen any with sufficient capacitance and voltage for for my amps. Still, I should continue to look.

Thanks for the info!

Cheers,
91.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

RE: Thank you!, posted on December 23, 2016 at 06:01:29
Mr_Steady
Audiophile

Posts: 866
Location: North Florida
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My recommendation hasn't change from last time either. Electro Harmonix Gold Grid. They sound good, and won't break the budget. I also still recommend the ALK crossovers for your LaScalas. Then your 2a3 amp will work perfectly with your speakers.

Merry Christmas!


------------------------------------------------------------------
Big speakers and little amps blew my mind!

 

Indeed it is..., posted on December 23, 2016 at 07:25:14
Ivan303
Audiophile

Posts: 34711
Location: Cadiere d'azur FRANCE - San Francisco
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So it looks like there are a couple choices of 2A3 for 'high power' (two watts or so) operation. This is good news as I intend to re-build my DIY-HIFI Supply 'Billies" which already accommodate the 2.5V mesh plate 300B's from China (microphonic). WE-300B's from Kansas are getting to be close to 15 years old and have no getter left but still play well.

Link below:



 

RE: Indeed it is..., posted on December 23, 2016 at 08:56:15
drlowmu
Manufacturer

Posts: 9548
Location: East of Kansas City
Joined: January 10, 2005
According to Dennis Fraker, any 2A3 from China is inferior, "trash", due to poor metallurgy. It MAY possibly sound OK when new, but it will soon turn to trash over time, due to poor metallurgy.

The best two 2A3s to use are the JJ 2A3-40, and the EMLs, period.

The JJ is, by far, the best value of the two, and what Dennis designs for and supplies in his 2A3 amps in 2016. He ran JJs at RMAF this year, see Herbie Reichert's reviews for Stereophile, of his listening experience.

Jeff

 

RE: Thank you!, posted on December 23, 2016 at 12:22:42
maxhifi
Audiophile

Posts: 498
Location: Alberta, Canada
Joined: August 4, 2004
Merry Christmas to you too!

Good to see you're still around here.

Nice to see an an endorsement for the EH tubes too.

 

Dennis talks 2A3... post-RMAF 2016, posted on December 23, 2016 at 12:31:51
91derlust
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"The JJ ...and what Dennis designs for and supplies in his 2A3 amps in 2016."

To clarify, Dennis prefers EML 2A3-M for best sonics. Read down to the last couple of paras of the attached link.

Cheers,
91.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

This style is what I meant, posted on December 23, 2016 at 13:28:15
maxhifi
Audiophile

Posts: 498
Location: Alberta, Canada
Joined: August 4, 2004



Russian pio

 

RE: Dennis talks 2A3... post-RMAF 2016, posted on December 23, 2016 at 17:51:18
drlowmu
Manufacturer

Posts: 9548
Location: East of Kansas City
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Yes, I was fully aware of that post. Here is a link to "the" most recent regarding this discussion.

Merry Christmas !!

Jeff

 

Question...., posted on December 23, 2016 at 18:10:11
drlowmu
Manufacturer

Posts: 9548
Location: East of Kansas City
Joined: January 10, 2005
Hello Dennis,

Please sir, what do you mean with this phrase ..

" they DO have to be connected directly to the rectifier D.C. output. "

Thanks.

Jeff

 

RE: Dennis talks 2A3... post-RMAF 2016, posted on December 23, 2016 at 20:22:10
91derlust
Audiophile

Posts: 401
Joined: December 25, 2014
A person could make themselves dizzy tying to follow... Thankfully, I have (only) a passing curiosity.

Have a great Christmas Jeff!

Cheers,
91.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

I said it was designed to accommodate Chinese 2.5 V 300B's..., posted on December 23, 2016 at 21:51:58
Ivan303
Audiophile

Posts: 34711
Location: Cadiere d'azur FRANCE - San Francisco
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I didn't say that it USED them.

The early TJ Globe 300B's were micro-phonic, later ones not so much. I have an early pair but they have not been in the amps for about 12 years.




 

RE: Dennis talks 2A3... post-RMAF 2016, posted on December 24, 2016 at 08:40:14
drlowmu
Manufacturer

Posts: 9548
Location: East of Kansas City
Joined: January 10, 2005
Thanks for the Christmas wishes!! It means something to me now-a-days.

I got saved, at a local Southern Baptist church in September 2015, so this, at my age, is only my second Christmas as a true believer in Christ.

Amen Bro'.

Jeff Medwin

 

RE: Dennis talks 2A3... post-RMAF 2016, posted on December 24, 2016 at 20:02:04
Tre'
Industry Professional

Posts: 11851
Location: So. Cal.
Joined: February 9, 2002
Dennis said " First of all, most NOS 45's, 2A3, 300B, etc., have a rectangular
plate structure, and usually a rectangular grid structure.

So far, so good. Now, what happens when we insert a non-symmetrical
part into this desirable arrangement-- we place into it a filament structure that is made like a cheap toaster-- a folded-up filament
mess that is "M" or "W" shaped. "

My question is,

What is the shape of the electron cloud?

Just because the filament is "a non-symmetrical part" doesn't mean the cloud is "non-symmetrical" and keep in mind the electrons do not go from the filament to the plate. They go from the electron cloud to the plate.

If the electron cloud fills the space between the filament and the grid in an even way then the fact that the filament is "a non-symmetrical
part" won't matter.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Thank you!, posted on December 24, 2016 at 21:11:01
Tre'
Industry Professional

Posts: 11851
Location: So. Cal.
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LCLC implies a critical inductance first choke.

Isn't lClC (little l) a better representation of what you are doing?

Kind of like when one adds a small cap to a critical inductance choke filter to increase the voltage a little bit?

Those are referred to as cLCLC with the small c denoting that the first cap will not make the filter act totally like a cap input filter.

Just like your first choke is too small to make the filter act like a real choke input filter. (each diode staying on for it's full half cycle)

Hey, it's just a suggestion to keep it real and not confuse anybody.

I wouldn't call a cLCLC filter a cap input filter and you shouldn't call what you are doing a choke input filter.

Yours acts much more like a cap input filter than it does a choke input filter.

There's no reason not to be honest about it.


Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

BTW, posted on December 24, 2016 at 21:13:52
Tre'
Industry Professional

Posts: 11851
Location: So. Cal.
Joined: February 9, 2002
In another post you said,

"First of all, most NOS 45's, 2A3, 300B, etc., have a rectangular
plate structure, and usually a rectangular grid structure.

So far, so good. Now, what happens when we insert a non-symmetrical
part into this desirable arrangement-- we place into it a filament structure that is made like a cheap toaster-- a folded-up filament
mess that is "M" or "W" shaped."

My question is,

What is the shape of the electron cloud?

Just because the filament is "a non-symmetrical part" doesn't mean the cloud is "non-symmetrical" and keep in mind the electrons do not go from the filament to the plate. They go from the electron cloud to the plate.

If the electron cloud fills the space between the filament and the grid in an even way then the fact that the filament is "a non-symmetrical
part" won't/shouldn't matter.

edit, by "fills the space" I mean the entire dimensional area.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Maximum Rg for jj2A3-40 fixed bias? , posted on December 24, 2016 at 23:47:28
maxhifi
Audiophile

Posts: 498
Location: Alberta, Canada
Joined: August 4, 2004
Would be fairly easy to change from cathode to fixed bias. Anyone know what the max Rg is for the JJ? I have 150k at present, it seems marginal for such a big tube in fixed bias.

 

RE: This style is what I meant, posted on December 25, 2016 at 01:53:22
91derlust
Audiophile

Posts: 401
Joined: December 25, 2014
Yep, that's similar to what I use for screen bypass. Unfortunately, those 1000Vers are only 0.5uF... I'd need 100 for each driver PS node and 250 for the output stage. It could be expensive and difficult to fit into the chassis.

Cheers,
91.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

RE: This style is what I meant, posted on December 25, 2016 at 05:53:24
maxhifi
Audiophile

Posts: 498
Location: Alberta, Canada
Joined: August 4, 2004
Oh that's right. I got that one to use as part of a hum cancel network in old RCA amps,
Thre original capacitor leaked an actual puddle of oil under the amp. My quest to replace like with like ended with those caps, and I was nicely surprised with how they tested so well.

They do have more appropriate values for filter networks. I have seen 10uf and 20uf at reasonably high voltages. I don't think you could design a whole amp around them but they're high enough to be usefully incorporated as elements of a filter network.

 

RE: Dennis talks 2A3... post-RMAF 2016, posted on December 25, 2016 at 07:25:12
dave slagle
Manufacturer

Posts: 4723
Location: NYC
Joined: April 27, 2001







The point that is fundamentally misunderstood by many is that the filament shape determines the effective anode area.

dave



 

RE: Dennis talks 2A3... post-RMAF 2016, posted on December 25, 2016 at 09:10:37
Tre'
Industry Professional

Posts: 11851
Location: So. Cal.
Joined: February 9, 2002
It is my understanding the coated filament of the 45, 2a3 and 300b produces a much more generous electron cloud than that of a thoriated tungsten filament.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Dennis talks 2A3... post-RMAF 2016, posted on December 25, 2016 at 09:23:26
dave slagle
Manufacturer

Posts: 4723
Location: NYC
Joined: April 27, 2001
The article I pulled those from was from 1929 which is the era of the 50.

dave

 

RE: Dennis talks 2A3... post-RMAF 2016, posted on December 25, 2016 at 09:56:21
Tre'
Industry Professional

Posts: 11851
Location: So. Cal.
Joined: February 9, 2002
Page 11 shows the "M" filament of a 211 utilizing almost the entire plate.

It's to bad that the book doesn't show the "effective anode area" for a coated filament tube.

Thanks for the link.

Tre'

Have Fun and Enjoy the Music
"Still Working the Problem"

 

I'll check it out - thanks! nt., posted on December 25, 2016 at 12:22:14
91derlust
Audiophile

Posts: 401
Joined: December 25, 2014
.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

RE: Dennis talks 2A3... post-RMAF 2016, posted on December 25, 2016 at 16:54:54
dave slagle
Manufacturer

Posts: 4723
Location: NYC
Joined: April 27, 2001
I think we may be interjecting a bit too much into the accuracy of the sketches. It does appear clear that the anode area is directly related to the filament structure. In the drawings I referenced there are curves around the corner which seems slightly more plausible than the sharp angles shown for the 211. I do strongly suspect that the edges are much more softly defined and and the "boxiness" of the drawings represents the average behavior over an area.

The point I was trying to put forth was that the filament appears to define the "active" plate area and while 100% "anode activity" may be achievable, I am not convinced it is a figure of merit that we should solely base out tube choice decisions on.

dave

 

RE: Dennis talks 2A3... post-RMAF 2016, posted on December 25, 2016 at 17:08:53
Tre'
Industry Professional

Posts: 11851
Location: So. Cal.
Joined: February 9, 2002
"I am not convinced it is a figure of merit that we should solely base out tube choice decisions on."

I agree and was just trying to point out that the electron cloud is much larger than the filament itself.

Some seem to think that the filament itself needs to cover the whole plate area or the tube won't sound good (or something like that).

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

While we're busy 'interjecting'..., posted on December 25, 2016 at 17:44:24
Ivan303
Audiophile

Posts: 34711
Location: Cadiere d'azur FRANCE - San Francisco
Joined: February 26, 2001

Can't help but suggest a serious consideration as to why some of us prefer the sound of 'round plated' tubes?





 

RE: While we're busy 'interjecting'..., posted on December 26, 2016 at 08:42:57
dave slagle
Manufacturer

Posts: 4723
Location: NYC
Joined: April 27, 2001
well.... since you are asking for wild ass hypothesis...

a typical "box plate" is planar about the cathode and has a grid and plate structure on either side effectively creating two distinct tubes in parallel. The Cylindrical model doesn't have the two discrete structures but a single one.

Now one can argue that in the planes in the "box plate" versions may (can) not be perfectly parallel leading to differing characteristics along the planes surface and the same goes true for the cylindrical version but the big difference I see is that the box plate model still has two distinct structures when viewed from the top and the cylindrical model will only have gradual change over the surface.

dave

 

RE: While we're busy 'interjecting'..., posted on December 26, 2016 at 14:18:44
drlowmu
Manufacturer

Posts: 9548
Location: East of Kansas City
Joined: January 10, 2005
Nice Dave, Nice.

Jeff, with an EIMAC 35T on my desk as I type this.

 

And I guess if you HAVE to parallel plates..., posted on December 26, 2016 at 15:08:48
Ivan303
Audiophile

Posts: 34711
Location: Cadiere d'azur FRANCE - San Francisco
Joined: February 26, 2001


;-)





 

RE: And I guess if you HAVE to parallel plates..., posted on December 26, 2016 at 17:26:17
dave slagle
Manufacturer

Posts: 4723
Location: NYC
Joined: April 27, 2001
A lot of these arguments fall apart for this very reason. The biplate 2A3 is bad because it is essentially two discrete tubes in parallel like the 152TL. By that same logic, the 45 is bad because it is also two tubes in parallel. The thing that finally sold me on this was comparing the EC8010 to the EC 8020. Both have the same Mu but the EC8020 has double the gm which translates to 1/2 the Rp. If you look at the tubes the EC8010 is simply an EC8020 with only one plate rather than a plate on either side of the cathode / grid structure so it can be argured that the EC8020 is simply a pair of EC8010's in parallel :-)

dave

 

RE: 2A3 Options - KR Audio?, posted on January 4, 2017 at 09:33:47
maxhifi
Audiophile

Posts: 498
Location: Alberta, Canada
Joined: August 4, 2004
As it happens for reasons unrelated to amplifiers I plan to take a vacation to the Czech Republic this spring, and being an audio guy I had to look at what's out there. Coincidentally KR Audio is located in Prague.

I noticed nobody mentioned the KR Audio tubes, amongst other recommendations. They sure do look nice on the website.. how do they compare to other options? Would sure be a cool souvenir, especially if it's possible to buy them without the markup an importer puts on them.

 

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