hifiluv Posted October 6, 2006 Posted October 6, 2006 itchy again.... also becos wife wants MP5 back, under "pleasure" to hunt for a tube for my office... got tis DIY tube. using 2x 6L6s as power tubes and 2 x 6SL7s as preamp. sound is quite unique, quite unlike the EL34s or EL84s that i m used to. what is interesting is got 2 volume knobs to individually control the 2 channel volume level, quite useful for me, becos the speaker distance fm my seat is not equal, so can use this to create the proper imaging. now sitting in my office, spinning Great Basso... beautiful tube sound ....once a tubie, always will be.... ;D
DIRTRUN Posted October 6, 2006 Posted October 6, 2006 Oooaah bro, You must be a great salesman lo... how you turn her around? Hehehe Dirtrun
hifiluv Posted October 6, 2006 Author Posted October 6, 2006 Oooaah bro, You must be a great salesman lo... how you turn her around? Hehehe Dirtrun i didn't... when the MP5 first arrived, i used it for bedroom setup... she liked the sound fm it... when i swap with Harmon Kordon... she commented she prefer the MP5, so tat gives me green light to look for a replacement for the office tube...he he.... ;D
hifiluv Posted October 6, 2006 Author Posted October 6, 2006 subliminal sales tactic *rofl* ha ha... n it works.... last nite when i brought the DIY home, i told her i will be taking the DIY to the offce and bringing the MP5 back, she says "ok".... ha ha...... ;D ;D
Smooth1624705821 Posted October 11, 2006 Posted October 11, 2006 Hi Hifi, tis unit, izzit fm ragman? Is the humming still there as claimed. Good price. LOL. ;)
DIRTRUN Posted October 11, 2006 Posted October 11, 2006 ha ha... n it works.... last nite when i brought the DIY home, i told her i will be taking the DIY to the offce and bringing the MP5 back, she says "ok".... ha ha...... ;D ;D You are DE man... Hehehe Dirtrun
hifiluv Posted October 14, 2006 Author Posted October 14, 2006 Hi Hifi, tis unit, izzit fm ragman? Is the humming still there as claimed. Good price. LOL. ;) yep, there is a slight hum on one channel, but it don't really bother me becos even at 1 metre distance if dont hear it, unless u put yr ear just next to the speaker. the 6L6 is a very interesting sound, its not like EL84 or EL34 but more robust. it takes about 1/2hr to warm up and the longer i leave it on, the sweeter the sound is. ;D
2100 Posted October 16, 2006 Posted October 16, 2006 How would you describe the 6L6 sound? BTW it is PP right?
hifiluv Posted October 16, 2006 Author Posted October 16, 2006 How would you describe the 6L6 sound? BTW it is PP right? if u know EL84s, its sweet and a little laid back. EL34, sweet but more punch. 6L6, not so sweet, a lot of punch... but yet when its fully warm up.... the sweet mids becomes stronger... also the overall sound is more forward... a bit like SS sound. if not mistaken, the Melody SP3, also runs on 6L6s. set whether its Push Pull, i hv no idea, being DIY, :P
2100 Posted October 17, 2006 Posted October 17, 2006 if u know EL84s, its sweet and a little laid back. EL34, sweet but more punch. 6L6, not so sweet, a lot of punch... but yet when its fully warm up.... the sweet mids becomes stronger... also the overall sound is more forward... a bit like SS sound. if not mistaken, the Melody SP3, also runs on 6L6s. set whether its Push Pull, i hv no idea, being DIY, :P I have EL84s as my headphone amp (Cayin HA-1A)...not really sure if that is good as a reference. ;D Yeah listened to the SP3 before...ok lar. This Sat if everything goes ok will be going for 6L6s driving 805s. Not sure what to mod after that..... But not expecting too much since it is Chinese (the iron being very impt as i guess it will saturate very easily).
hifiluv Posted October 17, 2006 Author Posted October 17, 2006 I have EL84s as my headphone amp (Cayin HA-1A)...not really sure if that is good as a reference. ;D Yeah listened to the SP3 before...ok lar. This Sat if everything goes ok will be going for 6L6s driving 805s. Not sure what to mod after that..... But not expecting too much since it is Chinese (the iron being very impt as i guess it will saturate very easily). incidentally my first tube amp was Cayin MT12, running 4 x EL84s, very good for vocal and instrumental sound, but pump up the volume and the sound will seems strained. i tried to play Pink Floyd, The Wall with EL34s tube amp, but it sounded very strange. one of the weekend will bring the 6L6 back and see if it can handle Pink Floyd...he he... so u got 6L6 tube as well, driving B&Ws? :)
2100 Posted October 17, 2006 Posted October 17, 2006 incidentally my first tube amp was Cayin MT12, running 4 x EL84s, very good for vocal and instrumental sound, but pump up the volume and the sound will seems strained. i tried to play Pink Floyd, The Wall with EL34s tube amp, but it sounded very strange. one of the weekend will bring the 6L6 back and see if it can handle Pink Floyd...he he... so u got 6L6 tube as well, driving B&Ws? :) A pair of EL84 driving a pair of Senn HD650 in triode mode, confirm will not be strained, probably get tinnitus before that. ;D And no problems with room effects. Nope, I hope to get the Mingda MC805-AA integrated, output is the big 805 giving out paper-spec of 40W in Class A SET, driven by 6L6. What I read is that 845/805 tubes need to be driven by big stuff like 2AC3/300B/6L6 for the the potential of big transmitting tubes to be realised. Won't be as refined as 2A3/300B SETs, but more weight. What I am worried is that the MIC output irons are not up to task (SET need huge heavy and high quality stuff, ala a lot of $$$), but bo bian since it is so cheap. I hope to be able to get a good copy (ie won't go up in smoke after a couple of days), then i'll mod some of the components inside maybe in a month or so. http://www.cattylink.com/PRO-MC805-AA.htm Check out audioasylum SET and tube forums. Darn hardcore, even mod the big 845 integrated into a PP mono block. Oh I am not using B&W, using an Acoustic Zen Adagio. The impedance curve looks benign enough, though it is not exactly low in impedance, hopefully it matches with da amp. I cannot use warm tube amps coz the spk is voiced to be slightly warm (according to the designer, Robert Lee).
hifiluv Posted October 17, 2006 Author Posted October 17, 2006 Wah... looks good ah..... let us know how the Mingda fare. i heard them during the recent hifi show. but to me they were playing it a bit too loud during the demo, so hard to say if sound is good. also as u know different cdp, spker combi will give again a different sound. but my experience with tube is tat they are quite "forgiving", they make even a entry level cdp and speaker setup sounds very good. tats why i never look back as far as amp is concerned. :)
Spunky Posted October 18, 2006 Posted October 18, 2006 u finally got rid of your consonance? Have u heard the revolution tube int amp at skyaudio?
hifiluv Posted October 18, 2006 Author Posted October 18, 2006 u finally got rid of your consonance? Have u heard the revolution tube int amp at skyaudio? no Consonance still w me. cold storage for the moment... :P about skyaudio tube, i hv not. hv u check it out? n what px? :)
Spunky Posted October 19, 2006 Posted October 19, 2006 think it's $2++k. but I think there's some discount. It goes pretty well with their hgp spkrs.
hifiluv Posted October 19, 2006 Author Posted October 19, 2006 think it's $2++k. but I think there's some discount. It goes pretty well with their hgp spkrs. Tks for the info. due to my current setup and listening being more in the bedroom and office, i m looking more into mini tube amp becos of portability. seriously thinking of bringing in the Yardland to play with...only 8Kg (the Consonance is 22Kg)... there is the Mini Houston which is selling very ex. other than tis, just wondering locally anyone selling mini tube amps?
2100 Posted October 19, 2006 Posted October 19, 2006 let us know how the Mingda fare. The 805 heat dissipation is no joke and heats up the transformer stressing it further. I think it may be prudent to blow the air-con directly down to it. Apparently still got issues....just do a goggle search and on the usual forums like diyaudio, audioasylum, audiogon. From some local forumers they also said be careful with thermal failures. Just a cursory search on diyaudio : I quote ... ---------------------------------------------------------- In my own case it has been as much fun or as much work as building an amp from scratch given the time and effort involved. I bought one of the early MingDa MC3008AB's. It uses a 300B cathode follower to drive a 805. As supplied, plate supply on the 805 is about 1050 volts, but for 30 seconds allowing heaters to warm before the 805 is biased on the hi B+ soars to very high levels, almost 1600 VDC that endanges the insulation in the output xfmers. I could hear PD (Partial Discharge) as faint static clicking in the loudspeakers as charge carriers re-distributed themselves in the insulation system within the output xfmers. This was a little scary! My re-design delays the hi-B+ until it has a load available.and the PD issue is mute (Ha ha). My early sn (#10) amp was using a big multi winding power xfmer of apparently good quality and with interwinding shields that provided separate windings for each 300B DC filament supply, each 805 DC filament supply, the master 6.3 volt AC filament supply, the high B+ and also the low B+ and the bias supply for the output stages. It appeared to be operating overloaded and became very hot quickly within the transformer enclosure which had no effective cooling airflow. The power xfmer was potted in epoxy which made heat escape to its own case difficult as well. The searing radiant heat provided by the large output tubes with glowing carbon anodes next to the black outer transformer case was no help either. The voltage doubler making the hi-B+ was employing input electrolytics that could not handle the extremely high ripple current and they got so hot that they failed and the near short circuit, not enough to take out the way oversized mains fuse (oversized by the factory to remedy an occasional surge related fuse failure problem that was not addressed properly), and the by now overheated power xfmer failed in a catastrophic short circuit of the HV winding rendering it as potted jink. This all occured when I let the amplifier play for about four hours shortly after purchasing it brand new. Ask me if at that time, was I impressed? Not so much. The good news was before it melted, it sounded FABULOUS !!! When i bought this amp I had a chance to ABC it with several other MingDa amps, one the MC34B which I also bought, has been trouble free as manufactured and which enjoy very much. From this MC3008AB amp I loved the tone, the SET presence and soundstage, and the command of the bass that you do not get with most SET amps (because they are wimpy) This one makes 40 watts/ch. I think the output transformers are sonically very good. They are physically quite large and appear well made. I finally had an amplifier in my home that I had wanted the likes of for years and I was not going to let this little meltdown spoil my fun. . Not having a proper replacement power xfmer, and not wanting to pay someone in North America $600 or more for a custom replacement with 12 windings, I decided to manufacture my own multi winding filament xfmer to take care of the specialized filament needs (these DH cathodes all have audio and bias on them and need to be separately shielded and isolated), and some high quality transformers I had in stock. I did not want to go with voltage doubler on the Hi-B+ so I used a 300 VA CCS rated Hammond plate xfmer (about 1300 volts CT IIRC) and full wave bridge into a beefy choke input filter. A large blue computer grade cap bank now delivers the Hi B+ with 0.1% regulation from no output to full output with both channels driven. Having to cram about 12 transformers into a chassis that originally held only three required some work to enlarge the case. I wanted this remanufactured amp to look better than the original so it became the object of several month's work. A hard maple case was made and finished in 18 coats of hand rubbed lacquer for a rich piano black finish. I employed a very unique control stage idea of my own conception which helps this amplifier stand out. I have upgraded the power supplies, enhanced user safety and improved cooling. I did not modify the original audio circuitry other than to roll some different tubes into the position of 12AU7 SRPP driver to the 300B which made a really noticeable improvement in available output power and sonics. I found the E180CC does a fine job in this hole. With 1050 volts on the plate caps of the 805's I decided that it would be a good idea to rig SS, zero crtossing relays with low voltage DC control looped through the protective cage over the tubes. With the cover removed the amp will not come on. The amplifier has also received proper attention to component cooling both under the chassis and in the upper transformer enclosure. A quiet squirrel cage blower is installed in the bottom plate that pressurizes the chassis, cooling the bridge rectifiers underneath which were not cooled properly from the factory, then up to the transformer enclosure which is really effective in keeping the plate and output xfmers cool, then finally forward to the tops of the 805's under the plastic top plate which keeps that cool and from deforming. This new amp has been my pride and joy now for about two years or more and has been in daily use with no problems. I like it so much I have plans to purchase, and similarly upgrade another when I can afford to. If you can end up with a $20,000 amplifier through DIY it doesn't hurt to acquire a spare. I am using the originally supplied ShuGuang carbon plate 300B's without any problem but never gave the Chinese 805's much time, replacing them early on with some nice vintage Westinghouse tubes that I had in stock. They are run at their full rated CCS plate dissipation of 120 watts each. The new amplifier weighs about 130 lbs and I need help to move it very far. It is bIG, as large as a big microwave oven. The spun aircraft aluminum footers contain full sized hockey pucks as the soft interface to the setting surface. I enclose a before picture of this model amplifier with silver trim, the picture of mine with gold trim was lost in a HD crash. In the next post I show the finished results of my handiwork. From a point of view of buying one of these Chinese SE 845 or 805 SET amps as a basis for upgrades, if you get one like I did with good output iron I think some of them I see on ebay are priced low enough that they represent a bargain just as a source of parts.
2100 Posted October 19, 2006 Posted October 19, 2006 There's one selling on the loft, 805 output driven by 300B. L'Audiotoire version, but modded. I am not sure about that, but I have some pix about the internals and awaiting comments on the construction. The high voltages inside the 845/805 amp is no joke, you would not want to short anything, even with your ELCB protection. (and mingda is dumb enough to overspec the fuse, why put it there in the first place then). Currently checking out the Almarro 318BN too (non NFB version). 6C33C output, one of the few Big Power types other than the 211, 845, 805, 807, 813 etc... with enough good power for Single Ended. Not too many tubes to roll (6C33C cannot be rolled as there is only 1 manufacturer), so just roll 1 6SL7 and 1 6SN7, a couple of coupling caps perhaps to Blackgate-NX....happy liao. 18W only though, down 3dB from the 805.
hifiluv Posted October 19, 2006 Author Posted October 19, 2006 The 805 heat dissipation is no joke and heats up the transformer stressing it further. I think it may be prudent to blow the air-con directly down to it. remember reading somewhere its not wise to blow cold air directly to the tubes as i may caused the tubes to contract / crack. KT88, 300Bs, 805 etc being huge tubes give out a lot of heat. tats why for me i stay with EL34s, 84s..... he he.... will lose out in power, but for my listening area don't need so tok gong lah... ;D
2100 Posted October 19, 2006 Posted October 19, 2006 So the tubes cannot get too cold, while the components/transformers cannot get too hot. So how? I guess you can't design too small sized an amp for things like this... the body looks really thin. http://www.mei-xing.com/English/E-CP/e-17.htm Oh yeah, even my Cayin HA-1A is dumb. 1 ECC83 and 1 ECC82, 2x EL84, the whole thing is not exposed at all and with my IR thermometer reading the internal components like caps/transformers they can be as much as > 85 deg C. So that is why I operate it with the case semi opened. Dumb isn't it? We are in Singapore, not a temperate country where room temps can be 10-15 deg C. Oh well, if you treat it as a 1 year Enzer product then of coz.... ;D
hifiluv Posted October 19, 2006 Author Posted October 19, 2006 fm what i understand, best to hv a tube amp sitting as the top component on a hifi rack so that its free to ventilated naturally. also agree with u about miniature tube, the argument is components, eg tubes and transformers are too close for adequate cooling, thus may lead to shorten life of both tubes and transformers. i supposed there is a trade off. my experience with tube so far - EL84s - very hot EL34s and 6L6 - moderately hot (surprising even tho,they are higher power) :)
Guest eedimax Posted October 24, 2006 Posted October 24, 2006 Hi I'm new to this website and a novice at tube amps. can anyone advise which is a better tube amp. The Cayin A-88T or the Conosance reference 8.8 To match up with Monitor Audio RS6 Silver speakers. many thanks :) eddie
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