You assume a lot. Nothing you wrote is based in reality. Clearly, you know little about this stuff. All you do is flip-flop opinions every day on which tubes you prefer and brag about how rich you are. We'll try to carry on without you.
@thomaskong I obviously don’t agree with your theory about tube amp usage - I just don’t think you can make assertions like that based on a singular experience with another amp. But I actually do appreciate your input to this group so I hope you don’t stop posting - you certainly do have more experience with tubes than I probably ever will.
Power tubes produce a lot of heat. The air inside amplifier gets too hot to accelerate deterioration of capacitors. Most electrolytic capacitors are designed to operate for up to 3000 hours at high (either 85C or 105C) temperature. At room temperature they can last 20000 hours or more. If you look at vintage tube amplifiers - they almost universally had main filtering capacitors on top of the chassis. Overheating was the main reason (along with saving valuable space). LM508/805 does not have any provision for cooling inside chassis where all filter capacitors are located. Adding a small fan or two would greatly help, but for some reason manufacturer decided not to go this way.
Yes, power tubes does produce a lot of heat but does it get inside the chassis would be my question ? Heat always moves up and if the power tubes are located outside the case, would it heat up the inside of the unit the same way ? I measured the 805 - the bottom measure 52C while the top is ~225C. The transformers are about 38C on the top. I tried measuring the inside through side slots (for the heat escape) and it measures 40C maximum. Though it does not give an indication how much temperature is on the power supply caps but I suspect they would fairly be within the 40-50C range.
Prolonged 50C exposure will likely result in 6000 hours life (if rated for 85C) of capacitors. This is in line with service life mentioned above. That still should be more than 5 years of service before repair is needed.
Regardless, what's the impact on longevity of cycling/cooling off the amp every X hrs ? Does it not hit 50C exposure after 15 minutes of warm up time anyways???? Why is 2 hrs some magic number? Is there a curve that shows cap lifetime vs average cycle time? Not trying to be argumentative, but this all seems like speculation. I will ask Line Magnetic and see if I can get a reasonable response.
There is no magic number. Temperature usually settles after an hour or so and then stays stable after that. Some datasheets for capacitors have curves of lifetime vs temperature vs ripple current. Usually the problem happens when you reach temperature within 30 degrees close to parts rating and have high ripple current. Designer has a choice to use capacitor that can tolerate higher current or reduce operating temperature. Some capacitors are designed for longevity, but they are very expensive and and can be found in military gear, not in consumer devices.
I haven't tried 7N7, but I did try a Sylvania 7F7 on the 6SL7 slot. For me it's a very nice tube, but the Sylvania 6SL7 WGT brown base (golden letters on the glass) is better, as it's also better than other 6SL7 tubes I've tried like Sylvania VT229, Brimar, Melz, Shuguang WE Replica and some Tungsol. Has anyone here also tried the Sylvania 6SL7 WGT brown base?
All makes sense. So maybe it’s worth rephrasing the question and see what people think. For context, I tend to use my amp for at least a few hrs each day but often don’t have a well defined schedule and certainly no planned ‘critical listening’ session etc. I often don’t know how many minutes/hours it will be until I am next going to listen to the system ... and always ask myself “should I leave it on idling for another 30 minutes or an hour or turn it off??” So the question is - after how many minutes/hours does the LM805 sitting idle impact the lifetime of both tubes and caps more so than an extra off/on cycle? And is it roughly the same for each or do the caps and the tubes have different optimal usage patterns?? Should one leave a SET amp on - even if idle - if they think they are going to use it again in X minutes?? What’s your magic number for idle time?
Hello, It's my first time on this forum. Sorry if I will write anything badly in English. I have got my New lm 805 ia. Previously had using demo piece for three months which sounded that good that I had to pick up my jaw from the floor. It had: 6sn7 stock eh tubes 300b lm branded tubes 805A-T PSVANE No branded 6sl7 In new piece got: 6sn7 eh stock tubes 300b lm branded tubes 805 LM branded tubes 6sl7 JJ New amp with those tubes does not Sound that good as demo one. I had listened my LM (break in) on normal volume level for 50 hours, but over 100 hours it played on very low volume level. Could hear anything when ear was 5-10 cm close to speaker. When replaced stock lm 805 tubes for 805A-T for a while, sound oppened dramaticly but still I could hear some grain? ( Do not how to say in English) Sound was not soft, was technical, not engainging. My questions are: Is break in working on very veeeery low volume level? Do I need longer time for break in or 6sl7 from JJ is issue? I will try to attach photo of 6sl7 from demo piece , maybe anyone be able to recognize brand.
What feedback setting do you use? 3 or 4 will cause things you are explaining. 1 is too soft and 2 is likely the best. Try both 8 ohms and 4 ohms output, that will change the sound too. You may try to replace 6SL7 tube with another brand. I use Russian 1579 tube. I found that it sounds better than stock 6SL7. It will take 20-30 hours of break in before it finally settles.
I use feedback set on 1 as I had on demo amp after try every option. Just received Sylvania 6sl7 GT about an hour ago. If seller was right tube is never used before. I got music end emotions from my speakers now. Banana came back on my face. Should be better after some time. Line Magnetic shoot oneself in the foot placing 6sl7 from JJ to this amp. I wouldn't buy it if i would get demo amp with that tube.
LM enthusiasts, I just got my LM-508ia today. I am waiting on a Tekton Lore Be. My room is 14 x 25 x 9. I listen to Rap, R&B, Jazz, Disco through Bluenode 2i at about 65db to 70db average or so. Stevie Wonder, Tribe Called Quest, Coltrane, Earth Wind & Fire type stuff. I want to pull the the cheap tubes that ship with the 508 out and keep them as back ups. I want a complete set of new tubes. My ideal sound would be ....in order of importance: 1) get good value, (don’t want to pay twice as much for 1% improvement, don't want a substantially inferior product to save $50, don’t want to skimp on a tube that is going to last 20,000 hours or splurge on a tube that last 1,000 hours, etc) 2) clear 3) dynamic 4) warm 5) 3d 6) “real” 7) non-fatiguing Can anyone suggest a complete set of tubes? Thanks
6SL7: Mullard ECC35 6SN7: Mullard ECC32 805: RCA 300B: EML 300B-XLS Took a *lot* of trial & error before finally getting this amazing combination!
I strongly recomend the Sylvania 6SL7 GTA brown base golden letters. It's amazing for the price (about 30 to 50 U$S if you can find it). This one looks just like mine, but it doesn't show the brand Sylvania nor the golden letters. It looks identical. 1-Vintage 6SL7gt WGT Sylvania Tube*Black Plate*D-Getter*TV-7 Tested*Brown Base* | eBay
The Sylvania sound is good but it doesn't come close to the Mullard ECC35. For a better deeper sound, the 7N7 is much better, in my experience. I'd say it's 85% there.
I compared it to the Sylvania 7F7 Etor recomended here and also against the well known Sylvania VT-229, Melz 1579 and Brimar. The Sylvania brown base was noticeably better than all of them. More holographic, stronger dynamics and better tone. Of course, my system, my ears and my taste. Also I think that it depends on the rest of the valves used, but totally worth to try for 30 bucks.
Well, you sure never lose an argument, haha. You must be a lawyer In my case, I had the Sylvania VT-229 in stock and I bought the Brimar and the Sylvania Brown Base from a site here in Argentina where I can return them for free and at about 20 bucks each, so the risk was zero. I only gambled about 60 U$S in total on the Sylvania 7F7 plus adapter and the Melz, both valves strongly recomended by well known members in this forum. I don't think the Mullard costs about 60 bucks and also some people find it a little bit soft. So, considering this and that the result will be user and system dependent (synergy with other valves, speakers, etc), the Mullard is a pricey bet. Sound quality can't be measured, but if your guess is that the Sylvania 7F7 is about 85% of the Mullard, I find the Sylvania Brown Base to be easily 15% better (if I could put a number on it) than the 7F7. Mostly with better realism, more lifelike. I'm not saying that the Brown Base beats the Mullard, but maybe it could be about the same level, with some stronger and some weaker points. If you haven't tried it, you are curious and you can try it with a free trial period, may be you can give it a shot. I would lend it to you, but we live far far away.
No argument. Purely logical. I recognize I'm in the minority but I never understood the concept of spending a fortune over buying many many cheap tubes when a single choice costing quite a bit on the onset will yield a better end result. Think of it this way; the higher-end tubes retain their value better. I've tried Mullard ECC33 tubes, Tung-Sol round black plates, and many more that I sold at nearly the same amount I paid for. The difference is what I equate to a rental fee. There are some good values out there but the very best tubes are no secret, hence their price which is not based on rarity; merely demand/hype. In the case of all the favorites in the field, I can vouch for their individual merit. It'd be easier if that were not untrue but this is a field that's been explored a million times over in the last 2 decades on the Internet so there are no more well kept secrets. You're correct that it's system dependent. I had a phono preamp which was very warm but since my components are inherently warm, it was too much of a good thing. That's why it's best to recognize what sound each component has to balance things as well as possible. As for price, I addressed that above. Again, all depends on tastes and gear. I know people who loooove a very bright sound; aggressively so. I can't stand it. To those people, the Mullard would be a bad choice. For those who like airy highs, the Sylvania is a good choice. Of course, as an example, if my speakers already produced airy highs, it would be a bad choice to add even more of the same characteristic. When wanting to buy tubes, it's best to quiz yourself as to what your system needs or would benefit from. Buying tubes at random is the worst way to go. Even if one of the tubes that are heralded as being in the top-tier is a bright tube but I don't need/want additional brightness, it would be a waste of time and money to bother getting it. In the end, you need to go where your ears take you which is what you seem to be doing.
