Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Stereomour => Topic started by: howardnair on November 12, 2010, 02:02:47 PM
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if one could -what 2a3 would one buy?
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RCA Blackplates, TJ Mesh Plates, Sophia Mesh Plates.
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Well, not having heard the stereomour yet, but having owned and currently owning a couple of superb 2a3 amps, I'd say that the NOS american valves have their appeal for their fairly laid-back presentation and classic "tube" sound. The absolute best 2a3 I've yet heard is the Shuguang 2a3z black bottle treasure series. They take forever and a day to break-in (typically recommend 300 hours), but once there are wonderful. Not quite as smooth, but less than half the price, and with very good bass/mid bass is the JJ 2a3-40s.
I have yet to hear two others on my short-list -- the EML solid plate 2a3s, and the sophia 2.5v filament 300Bs -- these were recommended to me by Jon Verhalen of Lowther America, who aside from his new GM-70s, has a pretty extensive collection of 2a3 amps and told me he likes these tubes best of all.
IMO, most of the upper echelon new production 2a3s -- those I just mentioned. leave the NOS americans in the dust, unless you happen to be looking for that classic sound. Also, the only 2a3s I've tried and could not take are the shuguang 2a3cs -- they are very thin and brittle sounding on my fi 2a3 monos, and sounded only slightly better on the tektron 2a3 reference integrated that I used to have. I'll take thesovteks over these anyday.
All just my opinion of course.
-- Jim
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Have tried the Sophia mesh plates 2A3 and the K&R 2A3 and both were spanked ( pretty hard I might add) by the RCA Black Plates I have in my Stereomour now!!! Not big on all the audiophile talk but I can tell you my feet are tapping now and the music has come alive whereas with the aforementioned tubes feet were still and music was kinda dull, YMMV of course.
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jim-grainger and shelby-you give me food for thought-i currently have the shuaguang 2a3c's in my stereomour-i am looking at the rca's ,shuaguang treasure's ,TJ''s and sophia's in no particular order-emission labs has a no go for bottlehead-i do not know what that is about-there is also the sophia princess mesh and the regular sophia to consider-what is the difference? jim you mentioned the sophia 300 2.5v for filament which i noticed on their site --what are the benefits and thought behind them-it seems a odd thing -a 300 where a 2a3 should be--thanks howie
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I have a couple of pair of old RCAs, one black plate one gray plate. I also bought Shuguang 2A3Cs a year ago. I thought they were amazing but only had the worn out Sovteks to compare with. I still think the 2A3Cs have a huge bang-for-the-buck.
I suggested the mesh plates since they were all the rage on the last board with the guys who owned highly modded Paramours and its predecessors.
The No-Go from Emission Labs has been discussed here. Search for it and you will find Paul Joppa's explanation. It has to do with the voltage they will see at startup.
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Howie,
The EML problem is constrained to the Paramounts because they are a direct coupled amp, and as Grainger says, it may be that the startup spike is too much for the tubes, but this is a special case.
Like the JJ 2a3-40 (*which is essentially a 300b with a 2.5v filament) the sophia is also a 300b with a 2.5 v filament (instead of the 5v that's normal for a 300b). Just a different sound -- typically with a bit more midbass/lower mid energy and less aggressive top end, though the sophias are said to have a wonderful top end.
HTH,
Jim
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Thank you Jim,
I remember that the thread mentioned that the new soft start board, coming soon to a Bottlehead site near you, would ameliorate the problem.
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I personally believe the new board will treat the EML gently enough in a Paramount, and the EML should be no problem in a Stereomour or other cap-coupled amp. However, I don't guarantee anything - I am not going to invest that much $$$ in an attempt to see if my designs can destroy the tube, nor am I going to run a 10,000 hour test switching the amp on and off every hour to determine if the tubes will survive long enough to be satisfactory.
Please understand, everyone, that the new board has some limitations. If you shut it off and turn it back on without waiting 30 minutes, the soft start won't work as well as it does from a cold start, and the EML could be damaged. The main purpose of the new board is to accommodate heat sinks more easily, and to allow an adjustable bias on the driver to set the driver plate voltage. The soft start was easy to implement, and it cures a grid-cathode spark that occurs with a few other new-design tubes, so we included it. These things, along with a small reduction in the regulated voltage, should increase the reliability of the board under severe conditions, especially excess power line voltage - which is becoming more and more common.
Also, I should mention that the 2.5v 300Bs run as 2A3s will run much more conservatively than regular 2A3s and should last much longer, even though they don't produce any more power. To my mind, that's their main advantage in a 2A3 amp. To get more power from them, you have to run them as 300Bs in a 300B amp which happens to have an available 2.5v/2.5A filament power supply. (Such as the Paramount, of course!)
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I
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In addition to the 300B for 2A3 tube offering, Sophia has a 2A3 for 2A3 offering that is an alternative that they seem to have more confidence in:
Princess 2A3 Mesh Plate Tubes for 2A3 Amplifiers
Option 1: $375 per premium matched pair with one year warranty (ceramic base).
Option 2: $325 per premium matched pair with 30 days warranty (ceramic base).
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Just curious why you say it appears they have more confidence in the 2a3 offerings than the 2.5v 300b?
-- Jim
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I think the EMLs are great sounding tubes. I find the EML 45 particularly nice. My guess is that there is apparently some difference in the way the emissive coatings are formulated and/or applied to the EML filaments vs. those of other 2A3s. The Paramour was never a problem for the EML tubes and neither will the Stereomour be a problem. They are both capacitor coupled between the driver tube and the 2A3, and thus the EML tube is protected at startup.
The EML tube cannot handle the startup cycle of the present, no soft start ParaMOUNT 2A3 amp (or the now retired Afterglow/Paraglow), which is direct coupled between stages. Other brands of 2A3s handle the startup cycle of the present Paramount without any trouble, but we have seen this incompatibility issue with the EML and it's AVVT 2A3 predecessors and direct coupled amps with solid state power supplies since around 2001.
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Just curious why you say it appears they have more confidence in the 2a3 offerings than the 2.5v 300b?
-- Jim
Because of the large difference in what they charge for a one year warranty. That is just my gut reaction.
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The Paramour was never a problem for the EML tubes and neither will the Stereomour be a problem. They are both capacitor coupled between the driver tube and the 2A3, and thus the EML tube is protected at startup.
Hi Doc,
What do you make of the EML ban on paper and oil coupling capacitors? (I have Jupiters for instance, which are beeswax and paper (oil??) )
On the EML site I think I ban on 'Large' coupling capacitors as well.
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The Paramour was never a problem for the EML tubes and neither will the Stereomour be a problem. They are both capacitor coupled between the driver tube and the 2A3, and thus the EML tube is protected at startup.
I'm not going to ask for you to guarantee it, but from your statement I will keep the EML "Mesh Plate 2A3" on my 'wish list'. I is rather pricey though.
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The Paramour was never a problem for the EML tubes and neither will the Stereomour be a problem. They are both capacitor coupled between the driver tube and the 2A3, and thus the EML tube is protected at startup.
Hi Doc,
What do you make of the EML ban on paper and oil coupling capacitors? (I have Jupiters for instance, which are beeswax and paper (oil??) )
On the EML site I think I ban on 'Large' coupling capacitors as well.
I don't know that what I think is relevant to what EML's policies are about capacitors. Clearly the pages of boilerplate on the EML site indicate that there are a lot of parts and circuits out there that the EML management feels are incompatible with their product. If something bad happens the tube guy is maybe gonna say it's the amp maker's fault. The amp maker is maybe gonna say it's the tube maker's fault. Whatever. The bottom line is the all the amp maker needs to do is supply someone else's tube that works in his amp in order to play it safe. The tube maker either has to come up with a solution or generate a list of warranty violations. I'd rather be the amp maker than the tube maker in that situation.
Once again, I think the EML tubes can sound very, very nice. For ten years the only tubes that arc over on startup in our DC amps have been the AVVT and EML tubes. It appears by now that this tube maker is not going to make changes to try to achieve the same level of compatibility with our direct coupled amps that other tube makers already have. So we simply sell a bunch of 2A3 amps with someone else's tubes. Even though we can just continue to do that and say "using EML tubes in our amps will violate your warranty with EML (note here that the warranty on our amp is not voided, but we will not replace your EML tubes if they go poof)" we have come up with a circuit that should make the EML 2A3 usable in our amp - assuming that the research that the manufacturer sent us and the conclusions he has drawn are correct. I don't have any problem with doing that, and I want to try to help our customers who are otherwise caught in a standoff.
My experience in the industry is that we have the greatest success when we work with suppliers who are equally willing to adjust and adapt their product to work with ours as we are with theirs. A great example of this would be Mike LaFevre of MagneQuest.
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The problem seems to occur when there is a positive grid voltage an/or grid current during the warm-up of the filament in EML tubes. Even a tiny leakage current in the coupling cap can create a hefty grid voltage before the filament gets hot enough to allow grid current, which I assume is why they ban any cap that can have significant leakage. Also, large-value coupling caps in combination with high grid to ground resistance makes a long time constant, and the charging current of the coupling cap can cause this high grid voltage for enough time to occur during the filament heating. I don't think there is a problem with 0.1uF and 250K ohms, which is what we usually use - but some amps use 0.47uF or even greater coupling caps.
In my humble opinion, EML is taking their best practical line here. Their tubes sound really good, and there is a high probability that is partly because of the cathode they use. So changing their tube's design would risk damaging the sonics, and the tube works well with many - probably most - amplifiers. They are up front about not using the tube in amps that can damage it.
You could say the the esoteric tubes are find in normal amps, and normal tubes are fin in esoteric amps, and of course normal tubes are fine in normal amps. It's the combination of esoteric tubes in esoteric amps where unexpected problems sometimes develop.
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if one could?-- i would!! and did-sooooo!! i ordered the sophia princess 300B 2.5--why? well pure and unadulterated curiosity--whether i chose the sophia 300B 2.5 or the princess 2a3 -a pair of rca blackplates-or even the emission labs--what i will have is music!--i worried about caps and resistors , speaker terminals ,goldpoint selector or stock -alps or stock-wiring layout-and on and on--before i built --then the wooden chassis-[i had to make quite a few prototype pieces]-the finish on the chassis-then consternation about upgrading the tubes--yikes--i would not have done it any other way--very enjoyable--so i will put the sophia's in the stereomour--and sit back and enjoy-i still say that the stereomour is more than a improvement over my cayin 860 modded mono blocks which are still resigned to the basement system and most likely will stay there until i sell them and build another something or other--howie
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if one could?-- i would!! and did-sooooo!! i ordered the sophia princess 300B 2.5
Hello Howard,
Did your tubes arrive yet? Any first impressions you care to share? Inquiring minds want to know.
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thoburn-Ye of Inquiring minds--i am very pleased with the sophia's-the sound in general is much more filled out-the bass especially-nothing is missing in the midrange and highs----{not that the shuaguang 2a3-c is a bad choice]---i hear more of the nuance of the music and the soundstage is very good-this with jazz- miles davis, kind of blue --glenn gould, bach --joni mitchell ,hejira-all lps--fm radio classical/rock--and my reel to reel, dave brubeck-i will put some rock on this evening-all in all good right out of the box-
a hhh yes HAPPY THANKGIVING EVERYONE--HOWIE
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Hi Doc,
What do you make of the EML ban on paper and oil coupling capacitors? (I have Jupiters for instance, which are beeswax and paper (oil??) )
On the EML site I think I ban on 'Large' coupling capacitors as well.
I don't know that what I think is relevant to what EML's policies are about capacitors.
What I am really asking is, "Would my Jupiter caps be a problem for the EML tubes"? They are not exactly PIO, but then I am not well versed in capacitor factors.
BTW, We live in Gig Harbor and are snowed in as well. May not be able to make it to my sister's house for turkey. Really sorry I sold my 4x4 pickup.
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Safe bet is don't use them. One the one hand I have a pair of custom Jupiters they made for me about 7 years ago that have held up beautifully and sound great in a big custom preamp with plenty of air flow and a very conservative voltage relative to the cap rating. On the other hand we have seen several Jupiters fail used in a S.E.X. amp chassis where it gets very warm. The Stereomour should run a bit more cool under the hood because of its vents (and the Paramount is pretty hot underneath - no Jupiters!), but I wouldn't take the chance. If you do decide to use them, keep them away from the hot bits.
No sign of the rain that is supposed to melt off the snow today. Looks like we may miss our big family Thanksgiving too.
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The EML tube cannot handle the startup cycle of the present, no soft start ParaMOUNT 2A3 amp (or the now retired Afterglow/Paraglow), which is direct coupled between stages.
Doc,
I'm using my verable Afterglows modified to use 45s. Is there a soft-start mod I could do to preserve the output tubes? Some ideas I've had are to put a damper diode in the PS (but where would I put the tube??), or one of those delays I've seen somewhere to slow down the B+? Of should I leave well enough alone?
Thanks,
Pete
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Are they arcing at startup?
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No, they're just elderly, and I was considering steps to increase their life.................
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I think with this, what, Mk IV version of the SRC4S board? we may get a manual written for its general use in other circuits, and of course this one allows for the implementation of a form of slow start that addresses the direct coupling of driver and output tube.
The versatility of the SRC4S makes writing a manual for it a real challenge. What we can do is give folks the basics of how the thing works and how to generally calculate the component values on the board. But the sticky part becomes whether or not the builder has knowledge enough to derive what voltages and currents they may need for a given circuit, and what changes they might need to make to the power supply.
Certainly to some extent we can help folks here, particularly with something like our legacy kits where the operating voltages and currents are known. What we haven't worked out yet is how to support the use of the board in modified or non-Bottlehead designs.
Give us a little more time to get this kit out as a Paramount upgrade first, and then we will look into writing some instructions for more general applications.
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OK, I'll keep an eye peeled for more general applications. Thanks!
Pete
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I'm using my verable Afterglows modified to use 45s. Is there a soft-start mod I could do to preserve the output tubes? ...
How old, exactly, are these amps?
The early Afterglows derived the driver plate current from the output tube cathode, and could not drive the grid positive under any circumstances. This appears to be the main danger to the new EML tubes. Not having tried it, I'm not going to guarantee it will work safely, but if it doesn't I'd be quite surprised.
This design makes it impossible to shunt-regulate the driver power, which is part of the reason the later designs (including the 2A3 Paramount) do it differently, but if you're cool with keeping the old design it does have that virtue.
As for extending the life, the power supply capacitors were electrolytics operating close to their maximum voltage specification, so replacing them might be a good idea if they're more than a decade old. The actual voltage depends on which power transformer you have (there were several) and of course on your line voltage. If you post the tube pin voltages, we can assess that situation along with the operating points which may have drifted - the bane of direct coupled amps.
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Thanks for the reply, Paul. I can't pinpoint when I built them - I had a pair of the original SEX amps, then got the TFA-204s to upgrade them, then got the Afterglow kits to use the '204s. I wasn't aware of variations on the Afterglows, but I'm certainly open to modifying them. The only mod I've done since I built them is to change the cathode resistor to use the 45 output tubes. I won't get to check voltages today, but I'll take a look soon. Is there a schematic of the later/latest version available?
Thanks again,
Pete
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Not quite as smooth, but less than half the price, and with very good bass/mid bass is the JJ 2a3-40s.
For those looking for a new stock 2A3 tube, I'll second this comment: I am very much enjoying my JJ 2A3-40s....
John
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Going back to EMLs......I read somewhere that the pins on the 45s (and probably the 2A3s) were fatter than is typical resulting in needing to bend back the connections in teflon tube sockets. Can anyone verify if this is true or false?
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Hi John,
Glad to hear you like the JJs. I have a couple hundred hours on mine now and the top end opened quite a bit more than it had been, so now I'm back to these as being preferred over my shuguang 2a3z Treasures. I think the Treasures will work really nicely with the Cornwalls though.
-- Jim
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Safe bet is don't use them. One the one hand I have a pair of custom Jupiters they made for me about 7 years ago that have held up beautifully and sound great in a big custom preamp with plenty of air flow and a very conservative voltage relative to the cap rating. On the other hand we have seen several Jupiters fail used in a S.E.X. amp chassis where it gets very warm. The Stereomour should run a bit more cool under the hood because of its vents (and the Paramount is pretty hot underneath - no Jupiters!), but I wouldn't take the chance. If you do decide to use them, keep them away from the hot bits.
No sign of the rain that is supposed to melt off the snow today. Looks like we may miss our big family Thanksgiving too.
Just FYI,
I have the Jupiter high temperature caps running in my Stereomour for 5 years now. They sound great to me and look just like the day I installed them. Do note that they are the high temperature variant.
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I have the Jupiter high temperature caps running in my Stereomour for 5 years now. They sound great to me and look just like the day I installed them. Do note that they are the high temperature variant.
That is good to know as i have a set of HT caps to put into my S.E.X. amp. They are rated for 70c max which is the same as the Mundorf Supremes, but they will have to endure a constant 30-40c which had me a bit worried.