julesb Posted April 13, 2016 Share Posted April 13, 2016 Just got a used one of these and I thought the fan was loud so I replaced it (straight forward by the way) with a top of the line ultra quiet fan with added insulation/upgraded gasket etc. The difference? Minimal! I think the problem is that the fan is probably amplified by the casing itself. Not noticeable in a band situation obviously but just slightly annoying when wanting to practice at home. At least I have a new fan... The piezo is a different matter. WTF with the horrible hiss?! It seems this is a consistent issue and I've read that others have replaced it with a low cost alternative(£12?) that has removed the hiss. I wonder how this could have passed any quality control as it just sounds defective. It is easily disconnected if you don't need it and therefore no more hissing. The mixture of the fan and piezo was very distracting. Apart from that this is a fantastic sounding amp that is unbelievably light. If only the fan could run at a lower speed when cool it would be perfect. Quote Link to comment Share on other sites More sharing options...
yorks5stringer Posted April 14, 2016 Share Posted April 14, 2016 Lots of us have just disconnected the piezo too, there is a thread on it as you don't just pull off the wires.... Quote Link to comment Share on other sites More sharing options...
synthaside Posted April 14, 2016 Share Posted April 14, 2016 (edited) I bought one of these new a few weeks ago .... The Piezo seems to be part snake .... I asked one of the guys at work, who has experience running PA systems from a former life of being the sound and light guy for a touring act. He Suggested if I didn't want to disconnect the tweeter ... thus void my warranty a baffle will do wonders for killing hiss , but not the bass sound. Test it by placing your hand over the tweeter on the grill ... If the hiss is drastically reduced ( which mine was ) . Buy some Foam and cut it to cover the region of the tweeter, attach this inside the speaker grill' back with duct or double sided tape . I bought this and cut then taped .... it to fit [url="http://www.amazon.co.uk/BLACK-NEOPRENE-PLAIN-SPONGE-RUBBER/dp/B00I0WWG0M/ref=sr_1_16?ie=UTF8&qid=1460650564&sr=8-16&keywords=foam"]http://www.amazon.co...6&keywords=foam[/url] Hiss = tamed Now if only i could silence that fan ... Edited April 14, 2016 by synthaside Quote Link to comment Share on other sites More sharing options...
julesb Posted April 15, 2016 Author Share Posted April 15, 2016 The company that sold me the super silent fan are sending me another brand to try (for free!) after I told them it sounded just as loud as the original one. I'll try that but am seriously considering getting an inline on/off switch for it so when I'm noodling at home I can turn it off. Obviously while keeping a very close eye on heat when it's not running. Quote Link to comment Share on other sites More sharing options...
julesb Posted April 16, 2016 Author Share Posted April 16, 2016 Fan noise solved! Just fitted this https://www.quietpc.com/na-ds-60 and it is perfect. Heads up to John at quiet PC for sorting me out. Had to modify the connector but entire job took twenty minutes and anybody can do it. I'm really happy now. No more hifi bass with a hairdryer as an accompaniment. Quote Link to comment Share on other sites More sharing options...
psb_87 Posted November 23, 2016 Share Posted November 23, 2016 Hi julesb, I'm about to do the same thing in my LMiii head, and I'm going to use exactly the same fan as you. I just wanted to ask, did you use the little voltage adapter cable with the resistor or did you just connect it at full voltage? Have you had any problems with overheating or cutting out since doing it? Thanks in advance! Quote Link to comment Share on other sites More sharing options...
Sparky Mark Posted November 23, 2016 Share Posted November 23, 2016 [quote name='psb_87' timestamp='1479894084' post='3180034'] Hi julesb, I'm about to do the same thing in my LMiii head, and I'm going to use exactly the same fan as you. I just wanted to ask, did you use the little voltage adapter cable with the resistor or did you just connect it at full voltage? Have you had any problems with overheating or cutting out since doing it? Thanks in advance! [/quote] You should check that the replacement fan specifications are the same or better than the original. It's when you're playing at high volume in a hot venue you will need the maximum air flow / pressure from the fan. Assuming both fans are brushless and capable of running at variable speeds dependent upon the amps cooling requirement, lower noise might be because of lower airflow. If you have an older class AB LM3 it will need all the cooling it can get under those conditions. Mine gets pretty warm and I would be very careful about replacing the fan. Quote Link to comment Share on other sites More sharing options...
stevie Posted November 23, 2016 Share Posted November 23, 2016 I'd second that. Fan noise is generally directly related to its speed. The Quiet PC fan you linked to only runs at 2,000rpm. Did the salesman point this out to you, Jules? Quote Link to comment Share on other sites More sharing options...
6v6 Posted November 23, 2016 Share Posted November 23, 2016 My LM3 went up in smoke (standard fan) so personally I'd be very cautious of replacing the fan with anything that's not moving the same or more air, and I'd be VERY cautious of using a switch to turn it off Without internal monitoring it's going to be very hard to tell when things are getting hot, and it only takes a short time for the power amp to get wrecked (mine was replaced under warranty, I think it melted one or more output transistors, lots of acrid smoke, fortunately at a practice not a gig, but it wasn't being run hard at all when it happened). Quote Link to comment Share on other sites More sharing options...
molan Posted November 23, 2016 Share Posted November 23, 2016 I did the piezo lead swap on a 121P and really liked the way it sounded. Sent the full signal through the 12" driver. Quote Link to comment Share on other sites More sharing options...
yorks5stringer Posted November 23, 2016 Share Posted November 23, 2016 Got to admit I hardly heard the difference when disconnecting the piezo and was never troubled by the fan either......what's that, it's 2.35! Quote Link to comment Share on other sites More sharing options...
julesb Posted December 9, 2016 Author Share Posted December 9, 2016 [quote name='stevie' timestamp='1479899115' post='3180082'] I'd second that. Fan noise is generally directly related to its speed. The Quiet PC fan you linked to only runs at 2,000rpm. Did the salesman point this out to you, Jules? [/quote] Hi, Just seen this so sorry for late reply. The air displacement was equal or greater if I remember rightly. This has been in since april and I have had no issues whatsoever. Cheers Quote Link to comment Share on other sites More sharing options...
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