Fang 0 Report post Posted August 6, 2006 Has anyone heard this amp with a beyer DT880 before? Share this post Link to post Share on other sites
haxyer 0 Report post Posted August 7, 2006 Yeah... Think might just call them up and ask them. Dun wanna make a special trip down. Was at SLS today so just popped down to ask around. anyway the real name is 4П1П and its believed to be produced during ww2 Share this post Link to post Share on other sites
leeyn 0 Report post Posted September 11, 2006 guys , anyone faces this LD2+ problem ? due to the intense heat (hence the cheap-paint smell), i unscrewed & took the transformer-cover off and drilled a few holes on top and side (8 altogether). i also sand-papered it and resprayed it with better paint (silver) from Nippon Paint. it certainly looks better. today, i fixed back the transformer-cover, 1.5 hours into listening (hot) - no more cheap paint smell (good) , but the LD2+ started a low but audible rattling-like hum (bad). it sounded like old flourocent-light hum - very likely from the transformer section. it's quite clearly heard if it placed near to the listener.... i did a left-right tubes switch, same problem after 1.5 hours (hot).... it has the same problem now even with or wothout the cover - argh ! my LD2+ is barely 1 month old... is this sign of poor quality ? anything can be done ? Share this post Link to post Share on other sites
Mackie 0 Report post Posted September 12, 2006 (edited) It's a sign of not being patient. The same paint aroma therapy occurs with XiangSheng amp as well but it will dissipate in a week or two on daily use. I'm afraid by drilling holes on the transformer cover, you have weakened its structure which is supposed to prevent excessive mechanical feedback (vibration) to the rest of the chassis. Anyway, I believe the tubes contributed more heat than the transformer. Hence, the ventilation holes on the cover of the latter do not rectify the heat issue by much. Edited September 12, 2006 by Mackie Share this post Link to post Share on other sites
leeyn 0 Report post Posted September 12, 2006 (edited) It's a sign of not being patient. The same paint aroma therapy occurs with XiangSheng amp as well but it will dissipate in a week or two on daily use. I'm afraid by drilling holes on the transformer cover, you have weakened its structure which is supposed to prevent excessive mechanical feedback (vibration) to the rest of the chassis. Anyway, I believe the tubes contributed more heat than the transformer. Hence, the ventilation holes on the cover of the latter do not rectify the heat issue by much. points taken/noted. while i do agree to your statement on inpatient - i don't call that aroma therapy ; try google "paint and health" and see/read for yourself.....(remember - this is cheap paint from china.) those 8 holes are small (4mm diameter).... will that still weaken the 'structure' ? the whole thing is still rock-solid as i screw it back on top-chasis. today - i manage to reduce the hum by adding a few ferrite cores to the power input line . . . peace ! Edited September 12, 2006 by Mackie Share this post Link to post Share on other sites
Mackie 0 Report post Posted September 12, 2006 (edited) Sorry, I accidentally hit the edit button instead of reply. Gees....U don't have a sense of humor, do U? Google principles on architecture and tell me if a few holes in foundation will weaken it or not. Of course, it feels rock solid to touch but it's mechanical energy we are referring to. If the structure isn't affected, do you deduce the change in paint actually causes hum? My solution, apply blue tack to reinforce and dampen the vibration from transformer to chassis. Ferrite cores...and a few too.....U just killed dynamics. We have discussed about ferrite cores and the related thread could be found using the forum's search function. Edited September 12, 2006 by Mackie Share this post Link to post Share on other sites
leeyn 0 Report post Posted September 12, 2006 points taken/noted. today - i manage to reduce the hum by adding a few ferrite cores to the power input line . . . peace ! I suggest not to use ferrite clamps on interconnects and headphone cables as they tend to stifle dynamics and thus resulting in a dull sound. Treble extension also suffers. However, these detriment may be less noticeable and even beneficial when used on power cords. Let your ears decide. cool. Share this post Link to post Share on other sites
Stereo_Electronics 0 Report post Posted September 12, 2006 points taken/noted. while i do agree to your statement on inpatient - i don't call that aroma therapy ; try google "paint and health" and see/read for yourself.....(remember - this is cheap paint from china.) those 8 holes are small (4mm diameter).... will that still weaken the 'structure' ? the whole thing is still rock-solid as i screw it back on top-chasis. today - i manage to reduce the hum by adding a few ferrite cores to the power input line . . . peace ! So it means you had the hum all along even before you mod the case? Share this post Link to post Share on other sites
leeyn 0 Report post Posted September 12, 2006 So it means you had the hum all along even before you mod the case? nope....she was all quiet and nice (except smelly like h@ll) - hums only notice-able / audible after my itchy-hands-tricks.... Share this post Link to post Share on other sites
Mackie 0 Report post Posted September 12, 2006 leeyn: Nice to see you research fast. However, using ferrite core to reduce hum will also reduce dynamics. This will be very obvious when playing back music with sharp transients such as cymbals clash or any form of musical climax. U may notice limited dynamics ie, a fast rolloff in transients when it could have extended further. Use the ferrite core by all means if what SE has mentioned above is correct, ie, there's hum before you mod the case. If the hum occurs only post mod, remove the ferrite cores and isolate the transformer from the chassis further (blue tack) until the hum is no longer audible. U could also employ velvet tape around the chassis in contact with chassis cover to reduce hum. Share this post Link to post Share on other sites
leeyn 0 Report post Posted September 12, 2006 (edited) isolate the transformer from the chassis further (blue tack) until the hum is no longer audible. U could also employ velvet tape around the chassis in contact with chassis cover to reduce hum. mackie, thanks. i afraid the blue-tack (that i knew) wont stand the heat... personally - i am prepared to sacrifice the dynamics (slightly onli nia!) as compares to those 2 : nasty humming and smelly metalic box..... thanks, again. Edited September 12, 2006 by leeyn Share this post Link to post Share on other sites
Mackie 0 Report post Posted September 12, 2006 Maybe you could request for a new transformer cover when another MO were to take place. Share this post Link to post Share on other sites
leeyn 0 Report post Posted September 12, 2006 employ velvet tape around the chassis in contact with chassis cover to reduce hum. how is this thing looks like ? where can i find them ? any url for ref please ? Share this post Link to post Share on other sites
Mackie 0 Report post Posted September 12, 2006 U can find it at any HomeFix outlet. Look for them in the velcro section. It's green in color. Share this post Link to post Share on other sites
leeyn 0 Report post Posted September 12, 2006 (edited) U can find it at any HomeFix outlet. Look for them in the velcro section. It's green in color. cool - THANKS ! i did another mod on the mod suggested.. :- i cut 4 small leather stripe (1cm length, 3 mm width - should not be easily flameable ?) and padded them below the transformer with the 2 side-screws tightened...... it looks like a small isolation platform.... wow : guess what - much-much less hum liao.... almost totally un-audible....unless u popped head very close to it.... Edited September 12, 2006 by leeyn Share this post Link to post Share on other sites
