rodders3 Posted May 20, 2019 Share Posted May 20, 2019 I just changed from 4 x Tungsol EL34b's to Gold Lion KT77's. Very noticeable increase in bass and punchiness and I'm very happy. Link to comment Share on other sites More sharing options...
F18 Posted May 22, 2019 Share Posted May 22, 2019 (edited) Generally speaking, a tube roll isn't going to give you you an extra massive difference in bass if you want "bass". If you want dramatic changes in a particular sound range or signature you look at the speakers followed by whats powering it. All changes from tubes are subtle in on itself. EL34's aren't bass monster tubes anyway, there reputation and use in audio came from the days of it being used in guitar amps for its tonality and mid range (especially back in the days when Mullards were the norm in every old school Fender, Vox, Peavey, Marshall etc. tube guitar amps) but remember tubes in guitar amplifiers are generally biased moderately to high class a and operating at 80% of the tubes parameters, harder than anything in a normal audio amplifier. Edited May 22, 2019 by F18 Link to comment Share on other sites More sharing options...
ForestForest Posted May 23, 2019 Author Share Posted May 23, 2019 On 20/05/2019 at 10:21 AM, Ihearmusic said: I can run your tubes through the tube tester to be sure. So i went around to Ihearmusic house with my amp and had a little play on his setup. Turns out one of the tubes was stuffed so switched in a couple Stephan had lying around and presto, sounded a lot better! Have just ordered some Gold Lion KT77's. See how we go on my quest now! Have to say that Stephan was an absolute gentleman in letting me come around and giving his time to help me out, plugging my amp into his setup for demo and his electronic knowledge is amazing. Would highly recommend listening to what Ihearmusic has to say in the future. 4 Link to comment Share on other sites More sharing options...
Lloyd Posted May 24, 2019 Share Posted May 24, 2019 (edited) On 23/05/2019 at 1:37 PM, ForestForest said: So i went around to Ihearmusic house with my amp and had a little play on his setup. Turns out one of the tubes was stuffed so switched in a couple Stephan had lying around and presto, sounded a lot better! Have just ordered some Gold Lion KT77's. See how we go on my quest now! Have to say that Stephan was an absolute gentleman in letting me come around and giving his time to help me out, plugging my amp into his setup for demo and his electronic knowledge is amazing. Would highly recommend listening to what Ihearmusic has to say in the future. Gold Lion KT77s are splendid. Again, you have chosen....wisely. I understand that the much cheaper JJ KT77s are also very good, too...with the caveat that some people grumble about occasional quality control issues. Apparently they are much better than they were a few years ago. You've ordered now. If you hadn't, I'd have advised you to request a matched quad with the highest plate current ("Ip") in stock. There is no majik number, but at a guess greater than say 60mA. Somewhere I have a quad measured at 80. Some guitarists like low Ip, maybe in the 40s and lower. I don't think it has any reflection on the quality of the valve, just its characteristics. You *may* be disappointed if, down the track, you plonk back in some EL34s. Edited May 24, 2019 by Lloyd Link to comment Share on other sites More sharing options...
Ittaku Posted May 24, 2019 Share Posted May 24, 2019 20 minutes ago, Lloyd said: You've ordered now. If you hadn't, I'd have advised you to request a matched quad with the highest plate current ("Ip") in stock. There is no majik number, but at a guess greater than say 60mA. Somewhere I have a quad measured at 80. Some guitarists like low Ip, maybe in the 40s and lower. I don't think it has any reflection on the quality of the valve, just its characteristics. Curious. What characteristics do you find different with different plate currents? Link to comment Share on other sites More sharing options...
aussievintage Posted May 24, 2019 Share Posted May 24, 2019 (edited) 14 minutes ago, Ittaku said: Curious. What characteristics do you find different with different plate currents? I too am curious. At first glance it would seem this a measure of plate current for a given plate voltage and bias condition which should not change unless the valve is weak - it is supposed to match the values on the valve curves after all. Little more than an emissions test? Edited May 24, 2019 by aussievintage Link to comment Share on other sites More sharing options...
Ittaku Posted May 24, 2019 Share Posted May 24, 2019 I ask because the matched valves my manufacturer chooses for my power amps are obviously chosen to have high idle current on the driver valves, but intermediate idle current on the output valves, and I'm not sure what their reasoning is or whether it was just coincidence that the matched sets happened to work out that way. They all have similar transconductance. Link to comment Share on other sites More sharing options...
Lloyd Posted May 24, 2019 Share Posted May 24, 2019 1 minute ago, Ittaku said: Curious. What characteristics do you find different with different plate currents? I'm not a guitarist so I can only go on what a guitarist mate of mine preferred. Something to do with breakup/sustain/distortion. And they have all those fancy pedal things, bias control and other gizmos as well. Higher Ip valves are "cleaner". More headroom and stuff. HiFi seeks to avoid distortion. 1 Link to comment Share on other sites More sharing options...
Ittaku Posted May 24, 2019 Share Posted May 24, 2019 Just now, Lloyd said: I'm not a guitarist so I can only go on what a guitarist mate of mine preferred. Something to do with breakup/sustain/distortion. And they have all those fancy pedal things, bias control and other gizmos as well. Higher Ip valves are "cleaner". More headroom and stuff. HiFi seeks to avoid distortion. Interesting. My guess is it makes no difference in hifi applications then during normal operation. Link to comment Share on other sites More sharing options...
Lloyd Posted May 24, 2019 Share Posted May 24, 2019 (edited) 24 minutes ago, Ittaku said: Interesting. My guess is it makes no difference in hifi applications then during normal operation. Someone more qualified than myself is probably in a position to explain better. Edit - I guess you could do a controlled A/B test with identical matched quads, one tested at 80 and one at 30. I too would be interested to know if there is a material difference. I am also guided by what Mr Weston advised when I was graced with his presence. I have no idea about different bias settings, makes my head hurt when I read forums where guitarists discuss these matters. The Topaz and the Trinity are cathode biased. Edited May 24, 2019 by Lloyd Link to comment Share on other sites More sharing options...
Lloyd Posted May 24, 2019 Share Posted May 24, 2019 (edited) 11 minutes ago, Lloyd said: oops, duplicate - will edit previous post. Edited May 24, 2019 by Lloyd Link to comment Share on other sites More sharing options...
Ittaku Posted May 24, 2019 Share Posted May 24, 2019 For what it's worth, in my limited experience once biased I haven't heard a difference between valves that are matched that are high idle current from those that are intermediate. That's from my 6550 days since I haven't changed many KT150s yet. Link to comment Share on other sites More sharing options...
Ihearmusic Posted May 24, 2019 Share Posted May 24, 2019 (edited) A valve is usually biased in such a way that the positive and the negative phase of the sine wave have the same amplitude. To little bias and your negative swing will start to bunch up and visa versa. If you have a look at valve curves you can see where the curves start to get closer together, (or where the valve gets into positive grid current, usually around the lower end of negative bias) That is Class A In Class A/B your change of bias will change to crossover point of the valves (one doing to positive cycle the other handling the negative cycle). It will show up as a bump on ether side of a since wave when seen on an oscilloscope. What I am saying is that a valve is biased at a certain point for a reason and unless you know what you are doing you should not touch it. If you fiddle around with your bias on your hifi amp you just might end up with more distortion, (which some like) Guitar amps are different altogether. They like to brake up early and have good distortion. Edited May 24, 2019 by Ihearmusic Link to comment Share on other sites More sharing options...
Ihearmusic Posted May 24, 2019 Share Posted May 24, 2019 Anyway, we had a good outcome with the OP's amplifier. A shame about the tube failure since the other three tested very strong. The amp did sound very good once we put a set of EL34 in (I only had a pair handy) My 300B was just a bit cleaner and had a bit more base other than that, a very nice amp from Earl at Weston Acoustic. Money well spent and most important, the money did not go to China. 2 Link to comment Share on other sites More sharing options...
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