Question About Tubes for Paramount

[mchurch]

This questions is directed to Paul or Doc but anyone is welcome to join in if they have an answer.  Can the Paramount amps handle the 300B -XLS tubes available from KR or Emission Labs. Since they are about 15 watts output would this affect the OTs or is there a mod I could try. I acquired a set of the KR from friend but I read somewhere there might be some issues with the Paramounts.

KR300BXLS

Low Frequency, high power triode. 15-24 Watts of pure class-A power

Maximum Plate Voltage    600 V
Maximum Plate Current    160 mA
Plate Dissipation    70 Watts
Va    450 V
Ia    100 mA
Vg    -94 V
Transconductance    5.7 mA/V
Amplification Factor    3.7
Filament Voltage    5 V (DC/AC)
Filament Current    1.8 A


Thanks

Mike

[Paul Joppa]

The filament current is too high - a normal 300B takes 1.2 amps, and these want 1.8 amps. I re-ran my numbers and it looks like it might work, but it involves exceeding some of the ratings by a small amount, so I can't promise it will work, or work well, or be reliable. The small Schottky diodes would have to be replaced with larger ones. the power transformer will get a bit hotter, the filament choke will be very close to saturation, and the filament voltage will likely be a bit low. Since the fiolament is capable of much greater current, that last should be OK.

Be aware that the amp will not put out any more power. The 300BXLS can operate at higher voltages and higher currents, in which case it would put out more power - but the Paramount power supply does not put out more voltage or current depending on what the tube label says!  :^)  It's like 140mph racing tires on a Chevette - it still won't go any faster.

[mchurch]

Thanks Paul;

Based on my limited knowledge of tubes and the design I kind of figured it would be as you say. It just confirms to me that I will probably keep these tubes for some other project or eventually sell or trade them. Since I wrote the original post I found out that KR also makes an good Western Electric 300B clone so maybe I'll roll these into the Paramount at some point.

Besides, right now the Paramounts are really good so change is not urgent.

Thanks again for helping me understand! This forum is really first class.

Cheers;

Mike

[trioid]

For what it is worth, I purchased a pair of the Emission Labs 300Bs (standard version) about 6 months ago. I am very happy with them.

Jim

[mchurch]

I have a set of KR 300B Westinghouse clones on order. They took the 300BXLS back from me in a direct trade as they had never been used. The new ones come with a 2yr warranty and are cryogenically treated as well.

Mike

[jdm]

I have been using Emission Labs 300B's in Paramounts since August 2010.  I am also very happy with them.  Much better than the electro-harmonix and better bass and focus than TJ perforated (faux mesh) plate.

Jim

[Oberst Oswald]

While I wait for my Paramount kits to arrive I've been thinking about another set of 300B tubes to buy.  As I write this the Genalex Gold Lion 300B tube is on sale for $243.00 for a matched pair.  Nobody rants or raves about these tubes and been wondering if these will sound any different than the Electro-Harmonix that come with the kit since they are both made in Russia.  Really not looking for a so called "better" brand at this rather low price range but something that my tin ears will absolutely know has a notable difference in sound from the stock set or not.  Does anybody own or have an opinion on the Gold Lions?  I can afford to get something more expensive/better but I would like to do that later down the road...

[Gerry E.]

Let me state up front that I haven't heard the Genalex 300Bs, but I'll take a guess anyway.  IMO, they are a bit of a gimmick with their white bases, fancy red labels and of course the famous Genalex name.  They sure look pretty, but I wonder if they sound any better/different than the other Russian made 300Bs?

It's kind of silly in the sense that there weren't any DHTs released under the original Genalex brand (AFAIK).  I believe MOV started using the Genalex brand name in the 1950s when DHTs were completely out of favor.  For me the bottom line is that even if the Genalex 300Bs sound a little bit better than other Russian 300Bs, you will want even better ones.  Why waste the money with this interim step when you can buy better ones when you're ready?

Gerry (Paramounts + EML Solid Plate 300Bs)
        

[patm]

I started out making the mistake mentioned earlier, not taking a big enough step. I replaced the stock EH tubes with winged c's from the fellow in Canada (Conus I think) An improvement for sure but not by a lot. About a year ago I got a pair of EML 300b mesh. What a difference, almost as much as the nickel xformers from Mike. Sometimes it's hard to know how far to jump. What helps me is comming here and learning from this OUTSTANDING bunch.

Pat McSween

[jdm]

Helmut

Gerry's and Pat's advice is consistent with my experience. 

Jim (Paramounts + EML Solid Plate 300B's)

[Paul Joppa]

I don't follow these things very closely so I may be wrong here. But I believe that New Sensor owns the Reflektor factory in Russia. They also own numerous brand names, including Sovtek, Svetlana (not the Russian Svetlana factory now sold as "winged C"), Tung-Sol, Gold Lion, Electro-Harmonix, and others. The base material, and whether the pins are gold-plated, are easy variations that give you a false sense that they are different inside. Some companies test and only sell the expensive ones, some companies buy up the rejects, it's a jungle out there.

Getting political, despite what you may have heard in Economics 101 markets are NOT perfect. And there's a lot of money to be made keeping it that way. It's nothing new, probably goes back to the dawn of trade some 10,000 years ago...  :^)