Steever Posted August 28, 2009 Share Posted August 28, 2009 Never really thought this an issue in the past but how warm should the mains transformer get on a valve amp? I can just touch mine but it's "uncomfortable" and almost ouchie. Should I be concerned? Link to comment Share on other sites More sharing options...
Nude Posted August 28, 2009 Share Posted August 28, 2009 Geez The thread Title had me worried for a bit It's normal for them to get hot, but how hot is the question? Which amp is it and have you any idea how hot it/they running? Link to comment Share on other sites More sharing options...
Sound Posted August 28, 2009 Share Posted August 28, 2009 Hey Winno, Read about ya woes glad ya got it fixed in the end....is it the same amp? In my experience with them they do get hot, if you can hold your hand on it for say 30 seconds and it becomes uncomfortable that's what I would call cool running and normal. I am no expert but hope that helps. And Nude your dry wit always puts a smile on my face:D Link to comment Share on other sites More sharing options...
caddisgeek Posted August 28, 2009 Share Posted August 28, 2009 I thought this was going to be about your latest trip to Thailand Link to comment Share on other sites More sharing options...
kye Posted August 28, 2009 Share Posted August 28, 2009 one of the guidelines of working with solid state (chips or transistors etc) is that they never get too hot to put your hand on for 30 seconds or more - below this heat is ok. a mains transformer would be far tougher than chips and transistors, but still, i'd be looking at cooling it down if you could. one thing that is often overlooked is ventillation - think about where cool air would be drawn in to replace the hot air rising from the transformer and make sure these airways are free for air to flow. passive cooling such as this can really make a difference.. but having said all that, valve amps certainly do get hot, and if the designer has done their sums right the fuse will blow if there's a problem so it might just be that it just gets this hot! Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted August 28, 2009 Share Posted August 28, 2009 (edited) Never really thought this an issue in the past but how warm should the mains transformer get on a valve amp?I can just touch mine but it's "uncomfortable" and almost ouchie. Should I be concerned? Sounds like it's running at about 60oC. Whilst it is probably too hot for electrolytic caps, which may be mounted nearby, it's not too hot for a transformer. Transformers can usually operate at around 90 ~ 100oC for extended periods. However, for a designer to allow a transformer to run warm, suggest several possibilities: 1) That a very cheap, crappy transformer is being used. 2) That the transformer is operating close to it's design limits. 3) That you are running a 220VAC transformer on 240VAC. 4) That you are running a 60Hz transformer on 50Hz. You should measure the temperature to be certain. You should also perform some more tests to see what is going on. Edited August 29, 2009 by Zaphod Beeblebrox Brain fart Link to comment Share on other sites More sharing options...
cableconnoisseur Posted August 29, 2009 Share Posted August 29, 2009 and got this.......... That can't be right !! Russ. PS: in relation to your tranny, is the amp a 240V unit or one of those lower voltage units on offer on EBay? Link to comment Share on other sites More sharing options...
Bronal Posted August 29, 2009 Share Posted August 29, 2009 LOL! and I thought I'd got the wrong forum for a mo'! Link to comment Share on other sites More sharing options...
andyr Posted August 29, 2009 Share Posted August 29, 2009 I understand Class A tube amps draw a lot of current all of the time (and so the power tranny might heat up more than a Class AB ss amp) but the power trannies in my Class AB ss monoblocks never get more than slightly warm. As Russ suggested, is your trannie designed for Oz 240v and 50Hz? I have heard that trannies designed for the American market, for instance, (60Hz) run hot at 50Hz - or is it the other way round? Whatever, I suggest you are asking for trouble to have the trannie getting too hot to touch inside a case with electrolytic caps nearby. Better send it to ZB or Earle for them to check out! Regards, Andy Link to comment Share on other sites More sharing options...
ehtcom Posted August 29, 2009 Share Posted August 29, 2009 Hi Winno. I see you recently changed your rectifier tubes from 5u4 to 5ar4 (gz34). This will mean that your HT voltage has risen by around ~30 volts. More power consumed = more strain on the power transformer. If your's is a 220V power trannie, then this only exasperates the problem. Also, (speaking from experience here) if you look inside the amplifier a 240v sticker on the power transformer doesn't necessarily mean it's a 240 power transformer. A well designed class A valve amp should have a power transformer rated close to twice the power consumed, bigger even better. Your dual rectified class A KT88 amp will be drawing around 280 to 320 watts idle. If it's a 220v version this will increase by around 20% and could possibly overload you power transformer causing eventual meltdown. Generally speaking, no-name Chinese amps have the minimum required, and sometimes a bit less. As ZB suggests, measure the temp of the transformer, not the cover, but the transformer laminations. If it's over 90 degrees you need to get your amp modified or run a step down tansformer. How long does it take for your power transformer to reach this temperature? Cheers, Earle. Link to comment Share on other sites More sharing options...
NT3 Posted August 29, 2009 Share Posted August 29, 2009 Have been running my 6L6 based amp now for 3 hrs. The power supply transformer is only mildly warm to touch. Think there may a problem there Winno. Is the amp a 240v version ? Our mains is a bit rough at times. With summer just around the corner might be an idea to get the amp of to a workshop. Link to comment Share on other sites More sharing options...
Sound Posted August 29, 2009 Share Posted August 29, 2009 (edited) Hey Winno.......know this is off topic..... But just listen to David Bowie"s "Fame" through my little Mengyue 6P1pp hooked up to my Hivi M4N speakers full range ..... Havent listen to this amp in months...probably in some's opinion a heap of rubbish...runs warm and we use a 240 to 220 converter......but geez in my opinion it is "real hot" Got that nice warm fuzzy feeling happening in the centre of me chest...... Cheers Edited August 29, 2009 by Sound whoops M4N not M4M :) Link to comment Share on other sites More sharing options...
cableconnoisseur Posted August 29, 2009 Share Posted August 29, 2009 Jannelle, Is THAT what's causing the heatwave we're experiencing in Brissie ? Russ. Link to comment Share on other sites More sharing options...
Sound Posted August 29, 2009 Share Posted August 29, 2009 Could be matey....could be.....betta go for a bike ride tomorrow and cool us all down:eek: Cheers and thanks for the smile:) Link to comment Share on other sites More sharing options...
Guest yamaha_man Posted August 29, 2009 Share Posted August 29, 2009 I thought this was going to be about your latest trip to Thailand Now thats funny! Link to comment Share on other sites More sharing options...
Guest yamaha_man Posted August 29, 2009 Share Posted August 29, 2009 and got this..........That can't be right !! Russ. PS: in relation to your tranny, is the amp a 240V unit or one of those lower voltage units on offer on EBay? But Cableconnoisseur wins hands down! Link to comment Share on other sites More sharing options...
Steever Posted August 30, 2009 Author Share Posted August 30, 2009 (edited) Thanks everyone for the comments - I wondered what images the title would conjure once I'd posted it... Anyway, I have had the technician (who also services amps from ARC, etc) who serviced my amp recently confirm that the amp is indeed the correct voltage and frequency for Australia. He's also confirmed that the GZ34 are also perfectly acceptable replacements for the 5Z3Ps that I still have. In fact, the 5U4GBs I had rattled and I lost quite a bit of gain as well. Evatco also confirmed after looking at my schematic that the GZ34 would be suitable. I took the time to substitute back in the 5Z3Ps and still had the high temp on the tranny cover. To clarify, I can touch it but it is quite hot. It's uncomfortable but bearable...just. But not as hot as the Musical Fidelity A100 or MA65s I had a while ago. I just thought I'd check, that's all. Thanks once again for the help. And I suspect that our power here in Fig Tree Pocket is not the best - Switching ceiling fan speeds mutes the TV audio for a second. Maybe that could be a factor, I haven't had it checked. Edited August 30, 2009 by Winno Link to comment Share on other sites More sharing options...
Guest Posted August 30, 2009 Share Posted August 30, 2009 dont get your rectifier mixed up in your tranny or you could have some serious rear end problems! Link to comment Share on other sites More sharing options...
Sound Posted August 30, 2009 Share Posted August 30, 2009 And I suspect that our power here in Fig Tree Pocket is not the best - Switching ceiling fan speeds mutes the TV audio for a second. Maybe that could be a factor, I haven't had it checked. Your suspicions Winno in my opinion are correct..... In my business your area is known for voltage dropping. Certainly wouldnt be helping matters....might be a good idea to invest in a "line conditioner" or whatever it is known as on here, especially as you seem to like the Chinese valve amps as much as I do:D Cheers:) Link to comment Share on other sites More sharing options...
NT3 Posted August 30, 2009 Share Posted August 30, 2009 Seems your amp has been checked out by someone whom is familiar with it. Did the tech make any comments about the hot running transformer ? It might be an idea to measure your mains voltage with a multimeter over a period of time. Take care doing this. Where I am the mains can hit 255v so invested in a variac. Link to comment Share on other sites More sharing options...
Sound Posted August 31, 2009 Share Posted August 31, 2009 Good onya NT3:D My man agrees with ya and reckons he really really really needs one of them variac things and that our Line-R 600 regulator is a poor mans version.... mmmm looks like my Mini Watt is going on the back burner:o Cheers:D Link to comment Share on other sites More sharing options...
andyr Posted August 31, 2009 Share Posted August 31, 2009 Seems your amp has been checked out by someone whom is familiar with it. Did the tech make any comments about the hot running transformer ? It might be an idea to measure your mains voltage with a multimeter over a period of time. Take care doing this. Where I am the mains can hit 255v so invested in a variac. And how exactly is the variac gonna help ... the only one I've ever seen is a manual rotary control which increases output AC voltage as you turn the knob - so do you sit beside this while you're listening, twiddling it to stop AC mains voltages from going above 240v? I suspect there are "automatic" such devices but they'd be called a "line conditioner", shirley? Regards, Andy Link to comment Share on other sites More sharing options...
cableconnoisseur Posted August 31, 2009 Share Posted August 31, 2009 Thanks everyone for the comments - I wondered what images the title would conjure once I'd posted it...And I suspect that our power here in Fig Tree Pocket is not the best - Switching ceiling fan speeds mutes the TV audio for a second. Maybe that could be a factor, I haven't had it checked. 4069 does have voltage irrregularities.......especially in the evenings . I'm a resident of that post code too;..just a little further up Moggill Rd... You may need to consider a dedicated line for your A/V set-up. In my case it helped a lot. Russ. Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted August 31, 2009 Share Posted August 31, 2009 And how exactly is the variac gonna help ... the only one I've ever seen is a manual rotary control which increases output AC voltage as you turn the knob - so do you sit beside this while you're listening, twiddling it to stop AC mains voltages from going above 240v? I suspect there are "automatic" such devices but they'd be called a "line conditioner", shirley? Regards, Andy There have been a range of automatic Voltage stabilizers available over the years. With the advent of cheap, high power semiconductors, the best ones are those that reconstruct the mains Voltage and allow the user to set and forget. Of course, any decent quality piece of equipment will already be designed to cope with a modes change in mains supply Voltage anyway. Rarely should such devices be required. Link to comment Share on other sites More sharing options...
andyr Posted August 31, 2009 Share Posted August 31, 2009 There have been a range of automatic Voltage stabilizers available over the years. With the advent of cheap, high power semiconductors, the best ones are those that reconstruct the mains Voltage and allow the user to set and forget. Well, yes, ZB. My point was ... are these devices called "variacs"? I would've thought they would be known as "voltage stabilisers" or "power conditioners (since they reconstruct the mains voltage)". Regards, Andy Link to comment Share on other sites More sharing options...
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