Hi Jet,
schematics:
http://www.drtube.com/schematics/an/quest.gif
And I know Andy Grove (AudioNote)a little bit...a smart engineer.
Matthias |
Hi Charles,
You are absolutely right...No problems for EML XLS tubes.
They are designed for 55W anode dissipation, not for 36(40)W only. For this tubes the "Frank" is easy. ;-)
You can read something about that here:
http://www.emissionlabs.com/datasheets/EML300B-XLS.htm
Yes, we work on modifying the tubes to improve the compatibility for some "special amps"...but this needs time.
For now we will replace failed tubes with selected tubes, tested at the same conditions as this amps are working(plus 10% safty margin)...
Regards, Matthias |
Hi Al,
It's hard for me to response (quick), because my contributions must be verifyed by an admin ;-)
ok...try this link for the datasheet:
http://www.mif.pg.gda.pl/homepages/frank/sheets/084/3/300B.pdf
And yes, the ER300B can handle more than 800V of anode voltage (not specified, but tested yet ;-))
It can handle more than 200mA too, but not at the same time ;-)
Our datasheet specified the power dissipiaton at 40W.
I have build some reference designs for using the ER300B in a perfect environment. All they working with very high anode voltage but with lower anode current.
It is very important the anode dissipiaton is not higher than 40W in any case.
As I measured, the autobias will work well using a 1kOhm cathode resistor if the tubes are very close to the design center values and close to the plate curves in the datasheet.
But tubes have deviations any time. I own a lot of WE300B. And they have differences between 53mA and 82mA at the operating point 300V/-58V...where they should have an anode current of 60mA. This is absolutely normal...and all the tubes of all other manufacturers have deviations...
The problem is not the deviation itself, the problem is the handling by the amp. Autobiasing is a nice feature...but not at the top end of the operating conditions! If this should be done, a potentiometer (for changintg the resistance of the cathode resistor or for changing the fixed bias voltage) and a ampere meter should be the minimum equipment...
The next question is how the heater voltage looks like in this amp.
If an EML 300B XLS is the right choice we have 1.5A heater current at 5V. There is no voltage regulation. A transformer a rectifier bridge and a CLC only. May be the XLS is underheated (so I hope) ore all other (right) 300B are overheated, because they draw 1.2A (some russians and chinese 1.25A)only. This would result a heater voltage above 5V...not so good for any 300B and very bad for an Elrog 300B, because the use of thoriated tungsten for filaments. Higher heater voltage will result a (much) higher anode current and a much lower lifetime...
Regards, Matthias
|
Hi Charles,
Why not work together with Israel? I am an open mind ;-) And I am lerning every day. Think You will have Elrog tubes working well with Franks without any changes in the amp. In the moment I'm collecting facts, numbers and values...then we will modify the tubes and all we are happy.
For me this is not a question of guilty...this is a challenge.
Regards, Matthias |
Randy,
AudioNote Quest Silver monos + ER300B = Dreamteam
(Try 8Ohm speakers at the 4Ohm tap...)
Regards, Matthias |
Hi Rob,
You can use ER300B in the AN Kit-1 without problems...
Because it's a kit I think You should have minimum skills at soldering and assambling. Thats why i suggest to add an additional resistor of 100Ohms(min 2W) between the paralled 1.5k Kathode resistors and the heater pin, so You get 850Ohms cathode resistor at all...resulting more gentle operating conditions.
Best regards, Matthias |
Hi Robert (Rwanda),
I could not find schematics of the Cary 300 SEI...But the description says 15W(!!!) watt per chanel (out of ONE 300B!).
May be, they use class A2 conditions (driving the tubes to positive grid voltage) or they use the absolute maximum operating conditions (450V/80mA) to get this 15W...
If this amps have a bias control and You can regulate the bias to 70-80mA, ER300B could be used successful. But I can not suggest this at the moment.
Best regards, Matthias |
Hello,
Yes, there are some challenges on the ER300B...
This tube is really new. The first series where build in October 2014. This are the first (300B like)tubes using thoriated tungsten as cathode/filament. To fit the 1.2A/5V filament specifications a VERY thin cathode wire is required.
That makes thinks difficult. An oxide coated filament is much more simple and much easier to handle but the sound is the same as the russian or chinese derivates...so we dicided, to build 300B like RF tubes using thoriated tungsten as filaments because the sound is MUCH better.
@brownsfan
We will replace the failing tubes, doesn't matter they where fail 2days, 2month or 2years post warranty.
Matthias |
Hi Rfprice,
No, we do not offer unlimited warranty!
Our warranty covers 2 years on materials and manufacturing and a half year for the emission.
It is a matter of grace for a new product.
It's very annoying if a tube fails, but it can happen. It is completely normal with such a new product. There are covert and late visible problems...And we can not by hundrets of different amplifiers to test the tubes...
But we can replace failed tubes by obligingness ;-)
Btw, 90% of all delivered tubes are working well.
Matthias |
Hello Bhchung,
Please excuse the delay in processing the warranty replacement!
It's summer and some of our employees are or were on vacation ... And Gary (Trueaudiophile) is a special case too.
So please, Brownsfan and Bhchung, send me a PM including the serials of the tubes, the type of the amplifier and an address, so I can solve any problems (if exist) personally on monday and ship the replacements as soon as possible.
Regards, Matthias |
Hi Dracule1
>Let's hope Elrog makes a version that can handle AC filament supply.
ER300B can handle AC filament supply...the problem is the residual hum...depending on the speaker sensitivity. Thats why we recommend DC heating.
The problem is the very small thermal mass of the very thin filament wires, necessary matching the heater specification of WE (5V,1.2A) using thoriated tungsten filaments (Filament temperature is about 1650°C instead of about 700°C).
We could build 300B using oxide coated filaments, but this would be another (boring) copy of the 300B only...
Using thoriated tungsten is the reason of sound improvment, because the behavior is very different.
Matthias |
Hi,I am an engineer at Elrog.
some thoughts about the realiability of 300B (and special ELROG ER300B)...in my bad english.
Yes, we have trouble in a handful of amplifiers when using our tubes...these are some models of "VAVAC", "Border Control", "Nagra" and now the "Franks" (aka. "Frankenstein").
Why?
Ok, let us study the "Frankenstein"...
There we have:
- 525V operating voltage with some drop (25V) over the OPT
- Makes 500V at the Anode
- because the 1kOhms cathode resistor we have 86.8V at the cathode
- results about 413V anode voltage
- at anode current of asbout 87mA
- so we have a plate dissipation of 35.93 W
35.95W this is very,very close to the WE datashhet for the maximum plate dissipation (36W)!
The old datasheet of the 300B says 400V Anode voltage as MAXIMUM...413V? In the newer version some "Recommended Operating Condititions" are included...the MAXIMUM anode currrent is specified at 80mA...not more...87mA?
Ok, the ABSOLUTE maximum is specified at 100mA...using self-biasing circuits...
And readable also:
"The life of the tube at maximum operating conditions will be shorter than at the recommended conditions"...how much shorter?...8000 hours 9000 hours...?!?
And now we return to the first point..."Design Center Values" of a tube...
Since all the times, tubes have a deviation in parameters...if not different specified, 10% are absolutely normal.
So, if I am a good ingeneer I go a little bit below the maximum ratings (this 10%)...And then I think about the deviations of the "mains"...115V are correct...but, what if there are 120V (or 110V)...there are another 5%...
Thats why I think the "Frankenstein" is NOT well done.
All is "on the edge".
It is very simple... a cathode resistor of 1.2kOhms will do the job...
The decrease of power is very small and the decrease of distortion is small also...BUT the tubes will last much more longer...doesn't matter this will be WE300B, EML300B TAK 300B ore ER300B ;-)
Regards, Matthias |
Hi,
May be, this reverse engineered circuit helps:
http://s89.photobucket.com/user/jeffreybehr/media/Coincident%20Frankenstein%20II%20monoamps/2014Mar20_Philsschematic2_1500w_zps98932676.jpg.html
I have simulated and measured with different tubes (WE, Psvane, Shughuang, Electro Harmonix...Elrog) The results are nearely the same...about 400V (405...420V) plate voltage (as Israel Blume responded) and the anode current was at about 80-90mA...a little bit more than 28W ;-).
Dissipation = anode current multiplied by anode voltage
If I take the 400 volts and 80mA (the lowest values) then it will result 32W. Using real measured values I get near 36W...not really cool running.
Gorge Lenz was talking about red glowing areas on the anode surface of the ER300B...We test and burn in the tubes at 400V/90mA (36W). If any tube is showing "red dots" on the anode surface while burn in or testing, we reject this tube immediately. So, if a tube has glowing anodes in a customer amp, there is a (massive) overload.
Btw, can anyone do some measurements on a real Frank?
I'm very intrested in the heater voltage using an EML XLS and an Elrog also. |
Hi Fla,
I have read the article in 6moons and the description on the manufacturer's site. Very nice amp with a lot of effort in details (huge capacitors in HV supply, dedicated heater supplies for each output tube, smart solution for changing the gain, switchable output impedances from 2 to 16ohms).
Very gentle operating conditions...30W dissipation per output tube only...So "Globe Mesh Type" 300B can be used. This tubes don't like stress also. This amp was build for ER300B ;-)
For best results You should order a matched Quad.
Best regards, Matthias |
Hello,
Thanks to snopro for his efforts on this topic...I received the results a day earlier ;-)
By my oppinion a variac is not needed. As can be seen all the measured tubes are having a little bit different operating conditions. All they are 300B fitting the WE300B datasheet (more or less) wthin the tolerances...The Takasuki's running a little "hotter" and the Psvanes a little "cooler". This is the effect of the deviations of real tube data...(against the design center values/plate curves in datasheet)
So the task is very simple. We have to select the "right" pairs of ER300B fitting to the operating conditions of the Franks (or any other amp whose conditions are known) in all cases(+10% or -10% main voltage) with a small safty margin.
A smart dealer like Gorge should be able to affairs which.
No variac is needed nor any changes in the amp...We only need to know the type of amplifier, so we can deliver the fitting tubes. (This way will improve the sound quality too.)
Regards, Matthias |
Hi Charles (and other Frankenstein owner),
May it be that the filaments of the Elrogs are very bright after switching on the amp for 2 or 3 seconds and then the brightnes is decreasing within the next about 5 to 10 seconds?
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