I suspect that the higher filament current of the EML 300B-XLS (1.5 amps per the datasheet at their website), compared to the 1.2 amp spec of the original Western Electric tube (to which the KR tube conforms) is a factor in the very long reported lifespans of the EML XLS that Charles referred to. The higher current draw will result in more voltage drop in the power transformer's filament winding and/or other power supply circuitry, resulting in less voltage being applied to the filament, compared to a 1.2 amp tube in the same application. The reduction in filament voltage would presumably result in greater longevity, and perhaps also contribute to the sonic character of the tube.
In any event, though, as you (Jkull) indicated you should verify that the amp can supply 1.5 amps to the tube without issue, if you want to consider the EML XLS.
Good luck. Regards,
-- Al
|
Almarg, with your experience, what would you conclude that I may find?
I have no idea, having no experience with 310A tubes or with LM amplifiers. But it seems like an experiment that is well worth trying. Especially given that based on eBay's listings of completed auctions for 310A tubes you appear to have purchased them at a very nice price, assuming they are as described. So if you end up not caring for their sonics you should be able to sell them for a profit. Enjoy! Regards, -- Al |
Hi Jkull,
If you look at the section of the 7701’s manual on "Crossovers" on page 129 (pdf page 132) I believe you’ll conclude (as I have) that you are most likely sending a full-range signal into the LM, even though the sub output is set to be active.
Disabling the sub in the 7701’s menus would add further confidence, however. Take a look at the two pages immediately preceding that one (127 and 128), and also note 2 on page 158. Although it’s all presented in a very confusing manner, it appears that it should be possible to disable the sub output by setting "Subwoofer Mode" to "LFE," rather than "LFE + Main," or alternatively by setting "Subwoofer" to "No" under "Manual Setup/Speaker Configuration."
Regards,
-- Al
|
Hi Jkull, Regarding your question above about the 7701, as you've no doubt seen it has a bewildering array of possible settings in its menus. After skimming through the manual, which can be found here under "downloads," I believe that in addition to the "Large" setting you mentioned, it would be best to select "Pure Direct" mode. Although the unit's display is apparently turned off in that mode, that will disable a number of functions and settings that could compromise the sound if not set appropriately, and is claimed to provide the best audio quality. And while I'm not 100% certain I believe that will assure that a full-range signal is provided to the LM amplifier. Regards, -- Al |
Thanks for the nice words, Mechans. I always value your comments about tube rolling highly, as I know you have particularly extensive tube-related experience.
FYI and FWIW the CBS tubes I tried were a quartet of 6SN7GTBs, having red lettering and marked as CBSs, not as CBS Hytrons. Three of them had a date code of 6026, which I presume means the 26th week of 1960. The other had no date code, but said "XG" in the location where the date code was marked on the others. They were in what I believe to be their original boxes. The box containing the XG tube said CBS Hytron, but as I said the tube itself said only CBS. The other three boxes said CBS Electronics. All four boxes referred to Danvers, Massachusetts.
I believe that all four tubes were true NOS, but in any event all of them tested fine on my Hickok 800a tube tester, and were well matched. I tried them about three years ago in my VAC Renaissance 70/70 MkIII amp. I recall that they sounded harsh and thin, compared to the several other vintage tubes I mentioned, as well as in comparison to currently produced Sophia Electrics. It is possible, though, that I didn't give them enough breakin time.
Regarding the comments you provided about 12AX7s, I'll second both the Telefunken recommendation and your words of caution. Also, I can report having excellent results in a different amplifier (a Chinese-made Paxthon push-pull parallel EL34-based amp) several years ago with the currently produced Genalex Gold Lion reissue that you mentioned. I've seen favorable comments here about that tube from others as well.
Thanks again. Best regards,
-- Al
|
Jkull, like the majority of phono stages the ZP3 appears to not provide a volume control. Therefore to be able to control the volume you would connect it to one of the 219ia’s inputs that does NOT bypass its preamp section (i.e., to one of the inputs other than "pre-in"). And therefore a 12AX7 upgrade is likely to be worthwhile. A follow-up regarding your earlier question about hooking up your sub. If you are willing to invest $207 (plus cabling) for that purpose, here you go: http://www.cs1.net/products/jensen_transformers/SP-2SX.htmAnd here is a link to the manufacturer’s datasheet: http://www.jensen-transformers.com/wp-content/uploads/2014/07/SP-2SX.pdfMany other devices claiming to perform the same function are available for much lower prices, but in contrast to most or all of them the products of the Jensen Transformers company are frequently used and are well respected by high end audiophiles. Good luck. Regards, -- Al |
If Al happens to be still following this thread I hope he’ll correct me if I’m mistaken. I was already composing my answer above when you posted this, Charles :-) And no, as usual you’re not mistaken. Best regards, -- Al |
Earlier I connected the oppo via XLR L channel analog output, into the SVS and something was NOT right. I got signal through to the sub but it was clearly audibly wrong with what I was hearing. I felt like I was hearing highs and miss [mids?] come out the sub as well...the sub has L and R inputs. The only thing I can think of that might account for that would be if the sub’s menus are set such that it is expecting its input signals to have been subjected to bass management, which I presume the Oppo does not provide. If so, you should be able to resolve that by changing various settings in the sub's menus. i cannot see it necessary to manually adjust my sub when adjusting my 219 volume. That sounds primitive and odd to me???? I would rather not use one if It cannot correlate in volume as I adjust the 219... ugh
Agreed. That would be very undesirable. Adjust the oppo volume is a no go as well. Then I guess the only remaining possibilities are not using a sub, or buying a different sub that provides speaker-level inputs, or trying to find a suitable speaker-level to line-level converter. Regards, -- Al |
If the sub provides speaker-level inputs (some do, some don’t) you would connect it to the speaker terminals of the 219ia, together with the connections to the main speakers.
If the sub provides only line-level inputs, since the 219ia doesn’t provide pre-outs (line-level outputs of its preamplifier section) the likeliest alternative would be to connect the sub to the Oppo. Either RCA outputs of the Oppo, using a splitter if necessary (so that those outputs could be connected to both the sub and the 219ia), or XLR outputs if they are provided.
You would then have to adjust the sub’s level control each time you change the 219ia’s volume control, to keep them in sync. Or, alternatively, if the Oppo provides a volume control you could use that control to change volume, and perform a one-time determination of a specific volume control setting on the 219ia and the sub that would always be used with that approach.
This assumes that the sub provides inputs for both left and right channels (if, as it appears, you are using just one sub rather than two). If you are using one sub and it only provides an input for one channel you would have to use a mixer of some sort to sum the left and right outputs of the Oppo together, with the output of the mixer being provided to the sub.
Another possibility is that you might be able to find a suitable speaker-level to line-level converter. I’ve seen such things offered over the years, at low cost, although I have no knowledge of their technical parameters or their sonic quality.
Regards,
-- Al
|
You’re welcome, Chris. I would not expect there to be any compatibility issues when using a 6SN7GTB in any 6SN7 application. And it would be very unusual for a 6SN7GTA to not be substitutable for a 6SN7GTB (or one of its modern counterparts which might not have any suffix), although based on the information I see in my Sam’s Tube Substitution Handbook it is conceivable that there could be a few oddball designs in which that might be a problem.
The possibility of an issue would mainly arise, though, if a 6SN7GT (or its VT-231 military equivalent) were substituted for either a GTA or a GTB (or their modern counterparts which might not have any suffix), due to the lower voltage and power ratings of the GT. Especially in a power amp or integrated amp application, where the tube may be driven at higher voltage and power levels than in a preamp or other line-level application.
Also, FYI my GEs are from 1958; I have no knowledge of GEs from other eras.
Enjoy! Best regards,
-- Al
|
Hi Chris (Waltersalas),
Regarding 6SN7 upgrades, a point to be aware of is that depending on the specific design of the amplifier in which they are used vintage 6SN7GT tubes (as opposed to GTA’s or GTB’s) may or may not be suitable. If you were to consider a vintage 6SN7GT I would suggest asking the distributor if it would be suitable for use in the 508ia before making a purchase.
Specifically, the vintage 6SN7GT is rated for a maximum plate voltage of 300, while the GTA and GTB are rated to be able to handle 450 volts. Also, the maximum plate power rating of the GT is 5 watts per tube and 3.5 watts per section, while the GTA and GTB ratings are 7.5 watts per tube and 5 watts per section.
Some and perhaps most recent production tubes that do not have any of those suffixes conform to GTA/GTB specs, so depending on the specific design a vintage 6SN7GT might not be a suitable substitute for a recent production tube identified only as a 6SN7.
Also, I believe the VT-231 that was suggested is equivalent to a 6SN7GT, and does not meet GTA/GTB specs.
Finally, FWIW I had used a matched quartet of 1950’s Sylvania 6SN7GTB’s in my VAC Renaissance 70/70 for a couple of years, with great results. One of them eventually developed a microphonics problem, and I replaced it and its counterpart in the other channel with a matched pair of 1950’s General Electric 6SN7GTB’s, which I have found to be excellent performers despite their low price. Along the way I’ve also tried Raytheons (pretty good), CBSs (yuk), and initially a new set of VAC-supplied Chinese tubes (one abruptly shorted out in a rather spectacular manner after two hours of use, and I haven’t let any of the others get anywhere near my system ever since).
Best regards,
-- Al
|
Even though I have long been and continue to be a fan of vintage tube equipment, in my mind the decisive factor choosing between the MC225 and the LM amps that have been mentioned would be the condition-related risks associated with the approximately 50 year old MC225. And even if you were to find an example appearing to be in excellent condition and/or well restored, the possibility that you may frequently find yourself wondering if it is truly performing as well as it once did.
Also, as I recall the MC225's reputation for providing outstanding sonic performance in relatively modern systems was largely established and solidified during the 1980s and 1990s, when roughly speaking it was just half of its present age.
Finally, as always I would attach great credibility to the comments by Charles1dad.
Good luck. Regards,
-- Al
(Former owner of a stereo pair of Marantz 2, Marantz 9, and Mac MC30 monoblocks; also a 7591-based Scott 299C, Pilot SA232, and many other well regarded vintage pieces).
|
[Edit: I composed the following before seeing mb1audio’s post just above]. Hmm. The comments by mb1audio prompted me to find this Stereophile review of the Line Magnetic LM-518ia. (I couldn’t find reviews of any of the other LM amplifiers that included measurements). With respect to that model, at least, a couple of things strike me as being significant concerns if the amp were to be paired with 102 db speakers: 1)The measured signal-to-noise numbers are definitely in the worrisome category, given that 102 db speakers will be used. I note that the reviewer used the amp with a number of different speakers, but I’m pretty certain that none of them are rated higher than 93 db. JA’s comment: Switching an A-weighting filter into circuit improved these [signal-to-noise] ratios to, respectively, 65.6, 67.4, and 68.8dB, which will be barely adequate with high-sensitivity loudspeakers.... Repeating the spectral analysis with the volume control at its minimum setting didn’t lower the noise floor. This suggests that the noise occurs after the volume control, which means that, unlike other amplifiers, reducing the volume won’t improve the S/N ratio. 2)Another of JA’s comments: The maximum voltage gain, measured into 8 ohms, varied with the output tap, but was appropriate for an integrated amplifier: 40.2dB (16 ohm tap), 38.6dB (8 ohm tap), and 36.5dB (4 ohm tap). In most circumstances those numbers are indeed appropriate for an integrated amplifier, but are significantly higher than I would consider to be optimal for use in conjunction with a 102 db speaker. The result may very well be having to use the volume control on the amp, and/or the volume control on any source components that provide a volume control, at undesirably low settings. Unfortunately detailed specifications or measurements don’t seem to be available for the other LM models that have been mentioned. But given the foregoing the comments by mb1audio raise some very valid concerns IMO. Hopefully reports of user experiences involving the other models and similarly efficient speakers can be found. Regards, -- Al |
I have sold my previous speakers, and will be picking up a pair of 60’s vertical cornwalls this week. 102db obviously means that i do not have to consider wattage as a factor at all. I listen at low to moderate levels generally. A further point in regard to the possibility of amplifier gain and noise issues arising with this speaker. The presently produced Cornwall III is spec’d at 102 db/2.83 volts/1 meter/"8 ohms compatible," which if the 8 ohm figure is reasonably accurate corresponds to 102 db/1 watt/1 meter. But I suspect that the speaker in question is the first of the two versions of the Cornwall II that were produced, which several online sources indicate was spec’d at 98.5 db/1 watt/4 feet. That corresponds to 100.2 db/1 watt/1 meter, rather than 102 db. So that 2 db difference will be at least slightly helpful with respect to the possibility of gain and noise issues arising with the chosen amplifier. Also, this paper may be of interest. Although note that the test results it presents are for the second version of the Cornwall II, that was introduced ca. 1981. Good luck. Regards, -- Al |
One more point I would add relates to the impedance plot for the later version Cornwall II that is shown on page 12 (pdf page 14) of the paper I referenced in my previous post. It can be seen that the impedance varies from around 5 or 6 ohms in much of the bass and mid-bass regions, to more than 20 ohms throughout most of the upper mid-range/lower treble regions, and to as much as 75 ohms in parts of that region.
Given the relatively high effective output impedance of nearly all tube amps, and the wide variation of effective output impedance among different tube amps, what that means (assuming the earlier Cornwall II has similar impedance characteristics) is that interactions between amplifier output impedance and the speaker’s impedance variations over the frequency range will very likely cause a given tube amp to sound significantly different with this particular speaker than with many other speakers, that have significantly different impedance variations. I have made that point in a number of other threads in the past, with respect to other proposed amp/speaker combinations, but I would expect it to be particularly true in this case. And the author of the paper makes similar points on pages 19-22 (pdf pages 21-24).
So that is a particularly important reason why if at all possible it would be desirable to audition the candidate amp(s) with the specific speakers you will be using. The amp's intrinsic sonic character is only a part of the story.
Good luck. Regards,
-- Al
|
Jkull, yes, I recognize that. To be sure it’s clear, though, my previous post relates purely to the tonal and sonic characteristics that will result from the particular amp/speaker combination, not to noise or other "unattractive and avoidable additional characteristics." And of course preferred tonal and sonic characteristics will tend to vary widely among different listeners, different rooms, and different ancillary equipments.
My point in that post is basically that sonic comparisons that are reported based on experience with the various amplifiers that have been mentioned may not hold true with your particular speakers. There are technical reasons for that, as I indicated.
Regards,
-- Al
|
To clarify further, I’m not saying that the impedance variations of the Cornwall will "hinder the sound." Most speakers have significant impedance variations as a function of frequency, in varying ways and to varying degrees. I’m just saying that a given tube amplifier is likely to sound somewhat different with the Cornwall than with many or most other speakers. I’m not saying that any such difference will necessarily be either for the better or for the worse with a given LM or other amplifier, or that any such difference would be more preferable or less preferable to you or to any other listener. I’m just saying that the sonic character of a given LM or other amplifier when used with the Cornwall stands a good chance of being somewhat different than what others may report when assessing the same amplifier with other speakers.
As far as the La Scala is concerned, after several minutes of searching I couldn’t find an impedance curve, and I have no particular knowledge of its internal design. So I can’t provide any insight as to how similar its impedance characteristics, and the resulting interaction of those characteristics with a given amplifier output impedance, may be to those of the Cornwall.
Good luck. Regards,
-- Al
|
Jkull 11-19-2016
Mids are where it counts most if I am left to chose. This was part of my
issue with my outgoing setup. Lack of presence in the mids and an
abundance of booming bass. An encouraging point related to that, for both the 508ia and the 219ia, is that you'll have a good deal of flexibility in tuning the mid vs. bass balance as a result of the three output taps each amp provides, and also as a result of the adjustable negative feedback each amp provides. Both of those choices will affect the output impedance of the amp. And as shown in the paper on the Cornwall I referenced earlier, the Cornwall's impedance in the bass and mid-bass regions is greatly different than its impedance in much of the mid-range, especially the upper mid-range. So the tonal balance of the amp/speaker combination will vary significantly depending on your choice of output tap and feedback setting. Hey, Wig, congratulations on the new amp! I don't doubt that your already wonderful system has become even better :-) Best regards, -- Al
|
The cornwalls are even somewhat ’dark’. The sound is very warm now. My concepts of maybe it being ’my room’ before, are much lessened. I can crank these and I do not feel like the bass is booming me and the treble is piercing me. The treble is warm but THERE. It is smooth and enjoyable. Midrange is nice too. Now the bass on the other hand... WONDERFUL....
I believe the cornwalls being so transparent and of such high sensitivity, that I am hearing the ’warmth’ of the marantz pre, heavily coloring the sound. However, it sounds pretty nice, an once I do give it some volume the dynamics improve. I feel pretty certain that the darkness you referred to will brighten and open up significantly when you replace the Emotivas with the LM amplifier, in part due to the resulting difference in the amp/speaker impedance interactions that I referred to earlier. The degree to which that will happen will vary depending on the output tap and the amount of feedback you select. And both of those choices will also affect the bass. So it will probably be worthwhile to try most or all combinations of taps and feedback settings. Enjoy! Regards, -- Al |
Hi Jkull,
First, congratulations! Glad the amp and speakers have worked out so well.
It won’t hurt anything to try the 4 ohm and 16 ohm taps. And it seems to me to be worth trying, as I suggested earlier. Given especially that the speaker’s impedance deviates widely over the frequency range from its nominal 8 ohm rating, assuming its impedance characteristics are reasonably similar to those of the later version of the Cornwall II. The reference I provided earlier indicated an impedance for the later version ranging from around 5 or 6 ohms in much of the bass and mid-bass regions, to more than 20 ohms throughout most of the upper mid-range/lower treble regions, and to as much as 75 ohms in parts of that region.
Regarding your phono stage candidates, I see no technical issues that would arise using the Decware with the 219ia and your Soundsmith Zephyr MkII cartridge. With the Bottlehead I would be a bit concerned about its very high output impedance of 4000 ohms. That would be reasonable in relation to the input impedance of the 219ia, but would make its sonic performance more cable sensitive than usual, on the output side. And I note that its website description states that on its outputs "interconnect cables of 1 meter or less are recommended." Although you could probably get away with a longer length than that if you were to choose a cable having particularly low capacitance (e.g., less than say 20 pf/foot).
Enjoy! Regards,
-- Al
|
