Angelo, if I'm not wrong, I don't think you need to bias a DA-8. My understanding is that this represented the power amplifier section of the DA60, which features a cathode bias topology. EL34/6CA7, KT77, 6550, KT88, KT90, and KT120 should all be plug and play. Of course, you could confirm all of this with Patrick. |
Hi,
Can anyone give advise on DA-8 tube biasing? What will happen if amp is not biased properly?
Regards,
Angelo |
Thanks for the link Sumonkabir those tubes look cool and the sales pitch seems plausible even if we can't confirm that it is meaniingful of true. The other possibility that I mentioned but haven't done is to get Gold Lion re-issue KT-77s which are a somewhat higher powered EL 34. I don't know if the bias needs to be changed but it shouldn't be majorly different than an EL-34. To be safe and certain just get a truly matched quad from a good vendor. If not buying from Trelja who on occasion sells some Chinese tubes get the from McShane Design over on Audio Asylum or by search. He really matches his tubes and trys every one of them to avoid sudden infant tube deaths.
Another tube to consider is theso called fat bottle Electro Harmonix 6CA7 which are equivalent to an EL 34 and are direct subs. They put out a really big sound although th Psvane tubes look a lot like the dimension wise. We talked earlier in the thread about the input tubes. |
Fantastic post for JOR owners. I like to try quad psvane Tresaure Mark II. Did anyone have any reviews and sonic experience with these tubes. Link below.
http://www.tube-sale.com/index.php/tubes/psvane-treasure-mark-ii-series/psvane-treasure-mark-ii-6ca7-tel34 |
Sure Joe, you know what I have a rarely used one that I don't need to protect so carefully, I will tell you here try stmechanic1@comcast.net I can only access it occasionally so forgive me for a slight delay. Once there I will update you on my current addy. Thanks for asking it has been a while my old friend! |
Thank you all for taking the time to help me. My JOR is up and running sounding, really sweet with Chinese EL34s and Teles 12AX7 ribbed plates. |
My apologies for the late reply, just arrived back from our summer vacation.
My JOR uses a 4A/250V fast blow fuse. Personally, I feel a slow blow fuse is always the better way to go in this application.
Doctor, can you let me know your e-mail address, please? |
Thanks Doctor,
The fuse cover does not have any information and the fuse itself is very difficult to read, I've tried Jadis and their US distributor with no success and my last hope is Joe who has been the "fountain of all knowledge" in terms of audio for me, a great guy |
The fuse ratings are typically on the fuse cover, and then again on the fuse. If all else fails see if you can download a users manual from Jadis. The other sources are probably commercial and would want a fee. Joe (Trelja might pop bback in to help you also. If not spontaneous start a new post. |
Thanks much Mattzack2,
Based on physical dimension I believe you are talking about the internal fuses which, I was told by Jadis, should be slow blow 0.5A and not 5A.
The one I need is located next to the power cable, easy to reach by unscrewing a fuse holder and about 1-1/2X longer than the other one. I believe this should be fast-acting but I don't know more.
Thank you so much and I hope I'm making sense since English is not my mother's tongue. |
Radio Shack
pn is 0218005.vxp
LITTELFUSE 0218005.VXP 5 Amp 250V Time Delay 5X20MM IEC Glass |
Hi,
I just blew the main fuse (AC) of my JOR last night when turning the amp on and unfortunately, I have no spares.
Can somebody give me the fuse characteristics and if possible, suggest where to buy them.
Thanks much, |
I am truly amazed at the difference that the JJ EL34L tubes have made. And at half the price of the KT88's I had been buying also.
Thanks again. |
Doctor, can you let me know your e-mail address or send me an e-mail(TRELJA@aol.com), please? I need to talk to you.
Mattzack2, what you and your friend hear from the JOR shows why it has won such a deep level of affection with me. You can get sound out of any amplifier, but to find one which puts music in your house rarely happens. Enjoy! |
I just had one of my audio buddies stop by to listen to the new tubes. I walked away to let him get into the music. Hr listened to Lee Ritenour first. He got so excited and emotional while listening to it that he just wanted to describe his experience to me. He listened to Dave Koz and Boney James before he had to leave.
He was amazed at the positioning, clarity, fast, clear bass and everything else he heard. He wants to come back this weekend with some of his reference music.
It was a good afternoon for both of us. |
It was great.
I learned a lot.
Thanks guys ! |
So glad to hear your impressions, Mattzack2.
Also, many thanks to you and The Doctor for making this one of the better threads I've been involved with in quite some time. Thank you! |
The tubes are excellent. I am really very happy with them. The only thing wrong is some crackling in the right channel during warm up. I am going to call Tube Depot and talk with them today.
Otherwise, I am am just letting the music take me away again. When the relaxation reaches the point of bringing you into the 'other worldliness zone", you know you are back in the right ballpark again.
Right now, I am finding the detail as clear and crisp as ever, the air between the instuments and voices is very obvious and the highs and lows are not lacking in any area. I still feel them breaking in and massaging the music into its final places though. They are definitely at least as good as the Gold Lion KT88s that I originally had in the system. The TungSol 12ax7's are in with the JJ's right now too.
I may try rolling and tweaking a little more in the future, but for right now, I am just going to enjoy the heck out of what I have.
Thanks guys. |
So nice to hear things are working out, Mattzack2!
If current bias sits at 120mV, I'd say goose it up to 150mV once the tubes are fully broken-in. Again, 150mV still represents quite a conservative setting. Can't really put a hard and fast figure on break-in time, but for me, it occurs when you are hearing no additional improvement. |
I have about 120 hours on the new JJ tubes.
Trelia, much thanks. I love the tubes. The soundstage seems to be much deeper and detailed. I am going to enjoy it for awhile before I try any other rolling.
And thank you, Mechans, for your valued input. This has been a very positive change in the sound of the JOR.
|
Hello again.
I just swapped the new el34l's into the amp about 15 minutes ago. I am initially setting the bias at 110mv for the time being. I will let them burn in for a few days and then check to see if the voltage had drifted at all.
By the way.... I blew the main fuse on the Jadis before I had enough time to read the voltages with the new tubes in. I set the pots to fully clockwise after replacing fuse and then slowly calibrated back up to 120mv just to get the feel of the voltage potential problems in this range and to make sure the tubes wouldn't blow the new fuse.
So I have a doctor appointment at 2:00 and plan on listening to some music tonight.
I am pretty excited to hear these new tubes break in. I am playing them pretty softly right now.
I have to run now. Thanks again. |
Heart attack, Mattzack2?!? WOW, that's serious in the kind of way we almost never get around here. Terrible news, I'm very sorry. I'm amazed how quickly you've gotten back into the game.
I've been in contact with JJ through the past year, and they maintain the blue and red glass have no influence on sonics. Years ago, a person (not at JJ) told me that to the degree the color (red, blue, clear) effect heat dissipation, sonics will follow. For whatever reason, the red tubes don't get imported by those who bring them in, as the blue was what folks went with in this market.
The Doctor and I participated in a JJ E34L vs JJ KT77 vs JJ KT88 shootout in the Jadis DA60 several years back, and drew some pretty stark conclusions from that. I'm not the fan of the JJ KT77 that most are. I've not heard the Gold Lion KT77, but hear good things about them. In the past year, I've purchased JJ EL34 and big bottle 6CA7 tubes. The EL34 have a more even-handed, fuller, richer sound top to bottom than the E34L, filling in that lower end. But, the E34L maintain that glorious midrange. As I just got the 6CA7 two weeks ago, and have been playing with other things of late, I've not yet tried them.
Doctor, the DA30 and DA60 are autobias (cathode bias) as you mentioned. In other words, the bias gets set by a "fixed" resistor connected to the cathode of the output tube, and cannot be adjusted without changing that resistor. The JOR is fixed bias, which means bias is set through a resistor connected to the control grid of the output tube. The term fixed bias is counter-intuitive, as it most often means that resistor is adjustable (potentiometer). A fixed bias amplifier can also employ a fixed resistor inline with the control grid of the output tube, which would not be adjustable without changing that resistor. Beyond having to manually adjust bias or not, cathode and fixed bias differ in their output power and sonic characteristics. |
Great discussion, I am really enjoying. I always wanted a Jadis Orchestra to try out, but I already have four tube amps, maybe down the line a bit... |
Hello Doctor. I did order the blue ones.
I also rearranged my listening environment to an area that has no hardwood reflection. The one thing that I feel is lacking is the sensation of being in a totally black void and just having the music suddenly just be there. KT88's did that for me. I am trying to recreate the same environment for the el34s.
I may try the KT77 tubes down the road, but I want to concentrate on the 88 and 34 shootout for the time being.
After I get the speakers aligned and the foam absortion set up, I think I will be in a better position to judge. |
Indeed I was going to tell you what Joe did. The JJ E34L is a different tube, I think IIRC that the height is slightly longer than the regular JJ EL-34. The other cool thing is that the E34L comes in colors. Trelja and I preferred the Blue glass. I am not sure but I think the color helped with heat dissipation.
Unlike Trelja I never noticed the loss of bass or low end extension relative to other EL-34s. It possibly true and Joe is rarely wrong about all things audio. I haven't had the matched octets necesarry to make such a comparison in a long time.
I am just wondering outloud, if you might want to try the Gold Lion Reissue KT-77 at some point. When I get my equipment back, I was thinking about putting the KT-77s in my DA-60. I will report my findings should I endevor to make the switch, but my amp is not a JOR, so it may not be very useful to you.
I have never rebiased the amp because it has an autobias circuit built in, and I am uncertain if I can overide the autobias, and bias the amp manually. It would be a PITA in any event the amp is pretty heavy and I am not young anymore. |
Trelja.... I'm back again. Heart attack slowed me down a little, but feeling a lot better now.
I ordered the JJ el34 L tubes and should have them in a couple of days. |
|
The JJ that I liked in this amp are the E34L, which do have a much different sound than their EL34.
The JJ EL34 is more typical of EL34 sound, with an evenness of hand from top to bottom. The E34L give up some of the bottom end for a midrange that can be otherworldly in the right setup. |
I plan on doing that this weekend. I will keep you posted. I wish I had a quad of jjel34's to compare. |
No, I think that is Joe Abrams of Equus Audio. I remember his banner ads here on Audiogon.
Please let us know how the amp sounds at 150 mV, and whether you feel the Mullard EL34 should stay. |
Understood
Are you the same Joe as your friend in the business by any chance? |
Mattzack2, thankfully, I've received two replies from Jadis. Both, from principals of the company.
The JOR conforms to the traditional means of calculating bias current. So, the calculations above ARE correct.
Patrick used 150 mV and stated, "the sound will be better but the tubes are not so secure." 150 mV / 5.62 would mean 27 mA of output tube current, still very easy on the tubes.
As I have maintained of late, I don't want to say much here in public regarding my personal experience, as it's prudent to have folks stay within the manufacturer's recommendation. |
Thanks....
It it really sounding pretty good right now. It might be interesting to see if it can be safely increased to 140mv or so. I am not concerned with tube life, but I want to avoid burning something else.
I will increase it as soon as I hear from you. It sounds very clear and airy right now. |
Mattzack2, your experience perfectly mirrors my experience when it comes to bias. As I said, as you increase the current flow in the output tube, outside of tube life, EVERYTHING gets better.
At this point, I don't want to encourage you to stray far from the recommended values. But I will say that if one calculates the JOR's plate current in the traditional manner, 120 mV divided by the 5.62 Ohm bias resistor would yield 21.35 mA, an incredibly (low) cold figure.
In comparison, my Dynaco ST70, which uses the same circuit, aims for a bias of 50 mA. The rule of thumb in the guitar industry shoots for 70% of maximum (25 watts for an EL34) plate dissipation, which obviously comes out to 17.5 watts. Though so many maintain the Dynaco's biased way too hot (415V B+ X 50 mA = 20.75 watts), I argue that after all these years you find so many with their original Mullard EL34, the assertion proves false. Figuring on the JOR's approximate 450V B+, at 21.35 mA, we're only at 9.6 watts, not even 50%.
I did send an e-mail to Patrick on Friday, but as of yet, have not received his reply. He's usually very prompt in these matters. We'll hope to hear from him soon. Again, I want to get his answer on the matter before saying to aim higher, as Jadis does employ a novel twist on connection to the output transformer, and the usual way of calculating these things might be very, very wrong. But, there's no need to back off from 120mV. |
Trelja-
I tweaked the bias up to 120mv and everything opened up immediately. I backed it down to 115mv and it sounds great. Lots more midrange detail and air. Bass seems crisper also but not as strong as kt88's as you mentioned.
Should changing the 12ax7's affect the bias at all? |
That would be excellent. Thanks. |
If you've reached the 100 hour mark, I think you're now hearing what the tubes are going to do.
"I am considering playing with the bias a little. I have it at 110mv now and was thinking of going to the recommended extremes of 90 and 120mv. What do you think of this plan?"
Well, I've been resisting saying this since the beginning of the thread, as I've seen the pocket protected high-end audio safety police go nuts in a "we're going to DIE!!!" scream whenever anyone suggests going outside of the manufacturer's recommendation. But I have experimented with this, and I have discovered that as with most tube amplifiers if you are interested in sonics, you want to bias the tubes hot (if you are bent on staying within the lines, think 120mV, not 90mV). This was demonstrated most starkly to me by an older gentleman who really knows tube amps, and biases his amplifier to the point where the plates of the tubes begin to glow, then (maybe) backs off a hair. The increase in everything - be it imaging, low end, warmth, and overall musicality is obvious. Of course, tube life suffers. Perhaps, dramatically. It's no concern to him, as he's not on the audiophile train, and uses a tube that no one has interest in, so he would have enough for his grandchildren that he acquired for nothing. But I don't want to suggest anyone try that as standard operating procedure.
Anyway, I can shoot an e-mail off to my friend at Jadis to find out if their novel (pioneered by the Quad II) transformer connection plays any role, or if we can simply figure plate current straightaway from the 5.62 Ohm bias resistor before giving you any hard and fast recommendations in terms of numbers. |
They are still breaking in I believe. They did seem to start filling the room nicely a few days ago ( about 100 hrs ago), but they have paused short of the kt88's at this point. I have tried swapping out the TungSol with Mazda 12ax7s's and EH12ax7's and the Mullards seem to still be shy of the holographic richness I am looking for.
I am going to continue burning them in for a while more. But I am considering playing with the bias a little. I have it at 110mv now and was thinking of going to the recommended extremes of 90 and 120mv. What do you think of this plan? |
Doctor, I would say you have more knowledge in terms of the 12AX7 and 5751 than I.
While I do feel the Sylvania 5751 Grey Plates have a bit more thunder down under, as you had also thoroughly evaluated the GE 5 Star and RCA variants, your insight and overall perspective surely betters mine.
Regarding the Shuguangs, I find they do not lack in the low end. Previous to finding them, there was no production 12AX7 that I felt held up against the tubes of yore. But outside of the JOR, where the lower gain potentially becomes an issue, I'll still take the 5751.
Care to provide an update on how break in left things, Mattzack2? How do you find the Mullard EL34 in comparison to your Gold Lion KT88? |
The Tung Sols are competent tubes that do their job in a somewhat understated manner in my experience, they have very good tonal balance. I would be hard pressed to say they are better than the Shuguangs. The Shuguangs have much better treble extension and are indeed cleaner than the Tung Sols now than you have got me comparing the tubes.
I was thinking that his choice for 12AX7 was a good one that really shouldn't have any negative impact on the overall sonics he is looking for.
Joe what would you say provide the most bass in that family of tubes? I remember when we were trying to buy 5751s and you telling me that the Grey Plates, while not your ultimate choice, had "thunderous bass". I found your description to be spot on, and never forgot it. |
Doctor, did you find the TungSol 12AX7 superior to the Shuguang 12AX7B? If so, that's quite a statement. |
The reissue Tung Sols are a very good current production 12AX7. I find them clean, clear with a strong signal that is full range capable, they rarely call attention to themselves.
Unfortunately the NOS supply of 12AX7s has dwindled and what's left don't look so good or are very expensive indeed. You may have more luck with 5751s which won't give you all of the gain you might desire but have exciting tonal qualities. They have been discussed ad-infinitum, so I won't say more than that you might want to investigate that option. I don't recall hearing them in the Orchestra but Trelja and I have DA-60s (unless he parted with his,) where they are fabulous 12AX7 subs. I will make one suggection. The most bass emphatic 5751 that we encountered was probably the GE Triple Mica Grey plates. They are not as detailed or as good in general as the 5751 black plate tubes tend to be, but will provide as much bass as any will, if you should see a continuing need for it. |
Very interesting .
I will check out those 12ax7's. I just bought these Tungsols but I am going to take your advice on them.
The Mullards have started filling the room and the lesser bass has become a nonissue. I am going to run it mostly Continuos over the rest of the weekend. |
Glad to hear the EL34 are improving. Here's hoping they get to where you hope.
The speakers I've paired up most with my JOR are Coincident, about 91 db/W. I've also had the Gemme Tantos - the first iteration, where the cabinetry was done in Canada, not China, and they are not especially easy to drive. Yes, you can certainly play and perhaps even like them. But I found they more come alive with emphatic solid state amplification.
Please keep us posted as to what you find over the course of the weekend.
For what it's worth, the current production triple mica Shuguang 12AX7B are the sleeper of this tube. The Doctor (Mechans) and I confirmed this several years ago to our surprise. We then hosted a tube shootout where they bested some very highly regarded old 12AX7 variants, and finished in the top three overall. |
I played music all night and when I checked the sound this morning it was starting to fill the room and was emphasing more detail. I am much less skeptical about themnow. |
I am driving a pair of Dali Helicon 800's at 89.5 db effiency which are no problem for the JOR. I even drive them with a 16wpc Carissa 845. I also have some Gemme Tantos that are a little over 90 but I prefer the Dalis
I am hoping to better the sound that I have with the GL kt88's. I love the holographic detail that I get with them. So far the EL34's seem very quiet in the bassiness and I'm thinking that should be improved with different 12ax7 tubes. I'd like to learn how good I can get the JOR to sound.
Which speakers do you have? |
I think you should be fine with the Mullards, Mattzack2.
The one thing I would say is to not put more than one variable in play at a time (Scientific Method), so that you can accurately assess the effect of each change. In other words, you should go back to your old 12AX7 for now to understand what the Mullard EL34 are providing. As the JOR employs the classic Dynaco (MKII, MKIII, ST70) circuit, the driver tubes play a pretty important role. Once you have a good handle (100 hours) on the Mullards, go ahead and reinstall the TungSol 12AX7. If things don't work out and you don't like the Mullards, perhaps I could purchase the from you?
The JJ E34L likely took a half day before I began to notice them, and a weekend (daytime, only) to really settle in. My speakers are pretty efficient, what are you driving with the JOR? Also, please remember to recheck/reset the bias.
Yes, same e-mail address, Doctor - TRELJA@aol.com and TRELJA@ultravioletaudio.com I've tried writing to you over the past year or so, but have had all my attempts bounce back to me. The NYC Show was great. In my most conservative estimation, easily five times the headcount of last year, with a much better venue. I'm sure as much of a success as turned out did this year, there should be substantial growth for next year's show. |
Joe do you still have the same e-mail I have been meaning to get in touch with you and perhaps visit. I have a lot to tell you about. My old e-mail will work if you want to try first. You know Micheal/Sufentil reached out a while back but I was terribly remiss in not answering, again a story with that. I seem have gotten disconnected from the PAAG. I know you aren't following them but If I had been in touch I would have made the New York Show.... I really should have gone to meet the industry people, I would love to get involved on that level. |
Thanks Trelja. That's what the manual stated but I just wanted to hear your thoughts since there was such a large difference in readings.
I am trying Mullards (new) because there was no JJ's that I could get my hands on immediately. I have about 12 hours on them so far. The bass is much softer than the kt88. I am not as concerned about that right now, but I am anxious the have the holographic sound stage back. I was wondering if the JJ's took very long to bloom. I also installed a pair of Tungsol 12ax7's at the same time, so I may be overly anxious to hear the same quality that I have been getting. |
The official bias settings for whatever tubes you use in the JOR are 90 - 120 mV, with 110 mV considered the preferred target.
As you noticed, at 10 mV, there is hardly any current flowing through the tube, and to draw an analogy with water, the valve (as the British call them, and a better and more meaningful name) is just about fully shut.
I like both the KT88 and EL34 in the JOR, but my preference is the latter. Of course, your tastes may differ.
Was hoping to see you in NYC, Doctor. Had a great time at the show. As you said, this new world of not being able to contact people makes things hard on everyone. |
