The franks have a very high operating point!?
- 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 across the plate of the Elrog.
If that's the case its way too high for the Elrog. Its probably too high the the Tak's and any other standard 300b tube. It could make for a very sweet operating point for the EML 300b XLS.
Its hard to believe that is the actual operating point for the Franks since Israel Blume has said he runs the franks conservatively.
If there was actually a 525V operating voltage coming from the power supply there would have been a warning to only use 300b tubes that could handle a plate voltage of 400 to 425v. Something is not quite right here -Jet |
Charles you may want to call Israel Blume. I find that this operating point would be hard to believe. It would fry any mesh plate tube and push any standard 300b to its limits:
"1kOhms cathode resistor we have 86.8V at the cathode at anode current of about 87mA." |
Jet,
I am a bit confused to some extent. Israel says the Frankenstein MK II is a "easy on the tube" design, heat dissipation is 25 watts and overspec transformers that operate at only 30% capacity. I can say that the amplifier is cool to the touch. The power transformer is only warm to touch when left on the entire day (never hot). I didn't have tube durability problems with my former Shuguang black treasures.i could have sworn at one time Israel said the Frankenstein ran relatively modest plate voltages(I could be mistaken). Bottom line, the amp sure sounds superb when good quality 300bs are used.
If the cathode resistor change settles the problem then this is very good
news. Matthias I'm assuming there's no adverse affect on the circuit (or other amplifier parameters) with this resistor change.
Charles, |
Charles I agree there is some confusion going on. A call to Israel will solve this. I would guess the Franks Power supply is outputting more or less 425v. And if it is somewhere around 425v no adjustments to the Cathode resistor would be needed. |
Charles,
Does your MKII incarnation of the Frankensteins have both an HT fuse and a second AC fuse?
It is my understanding that the HT fuse is intended to protect the Frankensteins in the event the 300B tube fails.
I am curious whether the HT fuse blew when your 300B tube failed? |
If the power supply is outputting somewhere around 425V that would mean the 300b tube would see a more conservative 325 to 350v acoss the plate depending on the cathode resistor value. |
Charles I think Doug has the test equipment to measure these tube paramaters on his test bench. Its nice to have a Techy friend in the audio business. |
Jeff,
It would be enlightening if he can measure plate voltage and other fundamental parameters.
Charles, |
Wondered if anyone can chime in on how the Elrog would be in a Cary 300SEI? I believe I have read somewhere that this integrated pushes a 300b a bit...or could I just adjust the bias down a little to try and compensate? thanks |
Israel blume responded to an earlier email today. He says the plate voltage of the Frankenstein is 400 votes, he says the heat dissipation is measured at 28 watts. He said changing the cathode resistor from 1 to 1.2 k ohms is technically okay but in his opinion will result in sonic deterioration. He further said that in the past four years he has had virtually no failures using the Pavane and Shuguang 300b tube. He Points out how cool running the Frankenstein amplifier is, he attributes this to using over Spec capacitors transformers and resistors.
I really appreciate Israel's response today, I can agree with him on the cool running Frankenstein and the durability and longevity of using Shuguang as well as EML tubes. I've decided to leave the stock resistor in place, and just wait for the tweaked/modified version of the Elrocg tube and go from there.
Charles, |
Hi Tmmvinyl,
My Frankenstein MK II was bought new in 2009, I believe this incarnation has only the HT fuse. No, the amplifier did not blow a fuse. I put in the EML XLS as replacements and everything is working and sounding fine.
Charles. |
I did not expect to hear that the Franks are indeed running 400v on the plate. That puts them towards the upper range and not a conservative operating point. I would think that's the upper range of what the Elrogs can handle. No wonder the EML 300b XLS sound so good.
A more typical operating point for the Western Electric 300b is 350v on the plate @ 60mA according to the Tube Data Sheet |
...and if the franks are set up to run at 413v @ 87mA. Many would say that's running 300b tubes pretty hard. |
Could running the 300b's at the upper end like that, shorten tube life? |
Jet,
I can't disagree with your assessment based on the numbers provided. It would explain my strong attraction to the EML XLS in this amplifier. I'm very curious to see/hear how the modified Elrogs turn out. If they can withstand the amp's demands and hold up I'll be thrilled. Sonically speaking Grade wise the EML = A~ compared to Elrog= A+.
Charles, |
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. |
I've just read through this entire thread, having been referred to it by Tmmvinyl today in another thread. Charles & Bill (Brownsfan), thanks for the nice words earlier in the thread. After examining the Elrog 300B datasheet, and comparing it with a 1939 Western Electric datasheet I have (as reprinted in the book "Western Electric Tube Data," published by Antique Electronic Supply), and also with a datasheet for the Psvane 300B-T (click "additional images" and then "enlarge"), in lieu of a datasheet I couldn't find for the non-T version which I believe is what Israel supplies, I agree with some of the others that there is cause for concern operating the Elrogs in the Franks. While the specs for the vintage WE 300B and the Psvane 300B-T look extremely similar, as was alluded to earlier the Elrog tube has substantially lower transconductance and amplification factor, substantially higher plate resistance, lower output power under similar operating conditions, and correspondingly different parametric curves. It also has a considerably higher (better) maximum safe plate voltage rating. I'm not 100% certain, but I believe that the net effect of these differences will be to cause the Elrogs to self-bias to significantly different bias points in the Franks than the Psvane or original WE tubes would bias to, and in the direction of being more stressful. And based on a quick look at the disparities between the numbers, I'm not sure that even changing the 1K resistor to 1.2K would be enough of a change for comfort. Charles, what I would suggest is that you follow up the response from Israel, in which he cited the 400V and 28W numbers, by providing him with a link to the Elrog datasheet and asking him if he can provide a rough indication of what those numbers, and also the bias current, would change to if Elrogs were used in place of the Psvanes he supplies the amp with. Also, unrelated to that, I'm wondering if Mk (Matthias) can provide a link to the WE datasheet from which he gets the maximum ratings cited for the WE 300B in his post above. Rather than the 36W and 400V numbers he cited, the 1939 datasheet I am looking at specifies "limiting operating conditions for safe operation" (what would probably be called "absolute maximum ratings" today) of 40W and 450V. Although it is made clear that those conditions and the 100 ma max current spec for self-bias should not be considered to be simultaneous. And a separate table defining numerous possible operating conditions indicates maxima of 450V @ 80 ma, which does correspond to 36W. But still, I don't see how to reconcile the 450V number I see in the datasheet with the statement by Matthias that "the old datasheet of the 300B says 400V Anode voltage as MAXIMUM." Best regards, -- Al |
Hello Al,
Thanks for your participation and insight. At this stage I will patiently wait for the new batch of modified Elrog tubes that presumably are better suited for the Frankenstein amplifier. Al, I know your VAC REN 300b amplifier is considered a highly tuned design that's said to be tough on the 300b. Are certain tubes selected/screened by Kevin Hayes to match the amplifier's demands? The Pavane/Shuguang black glass that Israel uses very successfully is a good sounding tube but not in same tier as the Elrog.
Charles, |
Hi Matthias,
This been educational, all I want is the superb sound the Franks/Elrog provide.lsrael said the resistor change you recommend will definitely lower the plate voltage but also result in sonic degradation. Wish you two could somehow work together (fantasy I know).
Charles, |
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
|
Matthias,
I do recognize that the Elrog is an excellent tube. The issue is the parameters/operating points of my particular amplifier. I'm very confident that I'll get a replacement pair that will work fine(now that the issue has been identified) and allow me to continue to enjoy their wonderful sound. Again I appreciate your expertise and input.
Charles, |
06-19-15: Charles1dad
Al, I know your VAC REN 300b amplifier is considered a highly tuned design that's said to be tough on the 300b. Are certain tubes selected/screened by Kevin Hayes to match the amplifier's demands? The Pavane/Shuguang black glass that Israel uses very successfully is a good sounding tube but not in same tier as the Elrog. Hi Charles, Yes, the VAC Renaissance amps run the 300B's hard, but according to Kevin, and also A'gon member "Raquel" (Drake), who as you know is especially knowledgeable about those amps, as long as the tubes are truly WE spec compliant they will have no problems and last for many thousands of hours. As "Raquel" said in this thread: I've owned VAC Renaissance amps for eight years. They require well vetted output tubes. In fact, Sophia used to market a special set of the Sophia tubes for VAC Renaissance amps, which were the basic Sophia tube, but particularly carefully tested at plate voltages that resemble the voltage that 300B's see in the Renaissance circuit. Generally, as for transconductance, output tubes for the Renaissance amps should test in the 3,000-5,000 range [edit by Al: I suspect he meant minimum, as the vintage WE's were rated a bit higher than that]. In addition, the plate-to-cathode voltage is approximately 430 volts dc, with idle current approximately 85 to 90 milliamperes in a self-bias (cathode bias) circuit. Again, this is approximately 5% below rating for the WeCo spec 300B. The milliamp and transconductance testing for purposes of matching must be done at those voltage levels.
I've always gotten 8,000-10,000 hours out of my output tubes, but tubes that are not good tubes will not hold up in the circuit. The tubes in my amp, which are Chinese 300B-98's, I'm pretty certain were purchased from VAC by either the previous owner or by the dealer he sold it to, very shortly before I purchased the amp. Their bases are marked with measured data apparently taken by VAC during their screening process. I've had no problems with them after several years. No doubt I could realize a substantial sonic upgrade by going to one of the upscale brands you've tried, IF I could be certain they could handle the operating conditions the amp would impose on them. But considering the cost of an octet of those tubes, or even a quartet if I were to run the amp in 30/30 configuration with four tubes removed, my recent investment in the DEQX HDP-5 you've probably seen me talking about with others in the current DEQX thread seemed to me to be a higher priority. As does a phono stage upgrade (probably to a Herron) at some point in the foreseeable future. Matthias, thanks for your further inputs. Best regards, -- Al |
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 |
Al,
Yes, that type of selection/testing for suitable tubes for the VAC is what Elrog will do for certain amplifiers to match the operation points. This to ensure a successful 300b and amp match. This is a smart move. Al your system must sound really special with your recent changes. I only hear/read good comments about Herron components.Thanks for providing that thread, I miss Raquel's postings.
Charles, |
Matthia,
I do appreciate your good attitude and knowledge. I can't wait to get these new modified Elrogs, what a sound you all have developed. Thanks.
Charles, |
Elrog's agreeable approach to finding a workable solution for owners of the Coincident Frankensteins is commendable. |
Thanks, Charles. I'm still fairly early in the process of "dialing in" the DEQX, which is a somewhat complex and lengthy one especially given that I've chosen to do it all myself without utilizing the optional service they offer of assisting remotely via Skype. But it's proving to be educational and fun, and even without its speaker and room correction features it's already providing significant sonic benefits just as a preamp and DAC upgrade.
Matthias, thanks for providing the link to the WE datasheet, which as you had indicated does state 400V, 36W, and 100 ma as maximum ratings, with the words "design center values" added.
So it seems that between issuance in 1939 of the datasheet I have, and issuance of the one you linked to in 1950, WE made their specs more conservative, for whatever reason.
And thanks also for the rest of your post, all of which sounds right to me.
Best regards,
-- Al
|
Charles I think you are in good hands and will be enjoying those Elrog tubes in no time and hopefully for a long time. As Spock once said Live Long And Prosper. |
Matthias also brings to the table an interesting observation about the current draw of 1.5 amps for the EML 300b XLS. It is 25% higher than a standard 300b which is 1.2amps. This is something I have mentioned in these pages to folks who were considering buying the EML's since they are considered drop in replacements for standard 300b's. I have over spec filament transformers in my amp that can handle the extra current so it is no problem but the bigger concern is that 25% extra current draw reduces the voltage accordingly. I noticed this when I first installed my new EML's. No problem since I can simply add or subtract the dropping resistors in my filament supply and I check my voltages regularly since I am a DIY person. This is not so easy for a person who is not.
All this to say that when considering different types of non standard 300b tubes it is very important to do the research to make sure your amplifier can handle this tube properly -Jet |
Jeff,
Yes, the problem has been discovered and competent people will correct it. George Lenz of tubesusa.com has been very responsive with me and in direct/frequent communication with Elrog, so I'm in good hands. They won't ship the new Elrogs until they've been fully tested at the specific needed parameters. That's fine with me. From this point onward people seeking Elrogs will be asked what amp are they using, this will ensure proper matching. I believe what I have experienced in this situation will help others.
Charles, |
Jet,
Wise observation and advice. |
Well, after waiting so long for my Elrog's. The Post Service lost my first pair. George was kind enough to send me another pair last Saturday (I wish I would have waited). I see I won't be able to use them with my Franks.
I hope George (Tubes USA) will exchange them for ones that will not be stressed in our Franks.
I did listen the them for a few hours. They sound very good out of the box, very smooth and refined. Hopefully, with more hours they would surpass the Takatsuki's, as of now I still like the Taks better in my set-up. |
Joe(Snopro)
Well you know my high regard for TAK and EML. The Elrog is very good "out of the box" and keeps improving with time. You may ultimately prefer the TAK in your system. In my case the Elrog was even more communicative of musical soul and emotion without sacrificing the good stuff of the other two tubes. For certain time will tell. Elrog just pushed "all" the right buttons in my system.
Charles, |
Matthias (or any others with the knowledge): any insight on how the El Rog 300B works in Audio Note Quest Silver monos? I have the low gain version (6J5 driver rather than 6SN7) but don't know the operating specs (and I'm no expert in these things).
I really like the descriptions I've read of the El Rog's sound, and almost ordered a pair more than once, but was cautious due to the failures I read about over on Head-Fi..
Thanks,
Randy |
Charles, it was just a quick opinion. Once they are fully burned in then comes the critical listening. I might just like them better then the highly regarded Taks and EML's, will see.
Hopefully, Elrogs team will come up with a solution.
Joe |
Joe maybe you sent them to your old address. LOL. |
Randy,
AudioNote Quest Silver monos + ER300B = Dreamteam
(Try 8Ohm speakers at the 4Ohm tap...)
Regards, Matthias |
Matthias, Were you able to find the operating points for the AudioNote Quest? I was looking on line and could not. |
Hi Jet,
schematics:
http://www.drtube.com/schematics/an/quest.gif
And I know Andy Grove (AudioNote)a little bit...a smart engineer.
Matthias |
Thanks Matthias; I'll likely give them a try 😀! My speakers are a pretty benign/relatively flat 6 ohm impedance so I'll definitely try the 4 ohm tap. |
Matthias,
Do you know how the Elrog 300B will operate with the AN Kit-1? Best, Rob. |
Mathias, what about the Audion Golden Dreams? They are parallel single ended triode (PSET) amps. Thanks...and your help is very much apreciated |
Hi Matthias
Can you tell me how the Elrog tubes will be with my Cary 300 SEI?
Vielen dank,
Robert |
Matthias, Thank you for sending the schematic. |
George Lenz gave me a call and asked if he can come over and get the voltage reading across the tubes in my Franks. This way we'll know for sure what the true voltages are.
The Elrog team wants to know and asked George if he can get them.
George is a stand up guy and is making sure that the Elrogs will work reliably in our amps. I commend him for his customer service and dedication.
I'll let everyone know once we get the readings.
Joe
|
Joe, if possible I would suggest that voltage readings be taken both with the Elrogs installed and with the tubes Israel originally supplied installed.
Regards,
-- Al
|
Ok Al, thanks for the tip will do.
Best,
Joe |
I agree that George Lenz has been very helpful here in working toward a solution for those Frankenstein owners who would like to use the Elrog tubes. |
Joe,
I received a message from George this morning asking if I could have someone measure my amplifier's plate voltage. This may have preceded him contacting you. If he can do your Frankenstein himself that's ideal. I also greatly appreciate his efforts to solve this problem. Joe I look forward to seeing your results with George.
Charles, |
Charles,
George at first asked me if I could get the reading. I told him I wasn't really comfortable doing it, so he said he'll do it when he has a chance to come.
That is very nice of him because he isn't to close by.
Joe |
