Cyber_Murphy Posted July 1, 2011 Posted July 1, 2011 Hi there, Time to post my new project!! During discussions on my ‘Class A mono-blocks’ thread, some suggested that the SC Ultra-LD MK1 might in fact sound better than the Class-A.. I was (still am!) very impressed with how my Class A’s perform, but, having also built the Ultra-LD mk1 (stereo kit) I was able to make direct comparison between the two. Sure, the Class A's lacked a bit of mid-bass punch and mid range “loudness†compared to the Ultra LD, but the “cleanness†of sound, channel separation and imaging, HF clarity, are better in the Class A's... But of course,, someone did mention that until I build the Ultra-LD with as much care as the Class A's, it would not be a fair comparison.. So, with that in mind I undertook the challenge! J My Ultra-LD already had some tweaks. I had removed the pre-amp, multiple inputs board, and the speaker protection module, and was using it as a straight power amp with single input. I had also by-passed most of the spade connectors and ‘solid terminated’ as many connections as possible.. But it still shared one power supply and case for both channels, and used the Stock Chinese toroidal transformer.. My first task was to source a couple of nice locally made shielded transformers,, which have just arrived today after a 3.5 week wait!! [ATTACH=CONFIG]33702[/ATTACH] [ATTACH=CONFIG]33701[/ATTACH] The Ultra-LD has 2 supply rails.. One is a fully regulated low current supply rail for the “class A†section, and the other is a traditional high current unregulated capacitive filtered supply for the ‘power stage’. Both of these supply rails are driven from separate 'center-tapped' secondaries on the single transformer.. More to come.. Cheers, CM
Zaphod Beeblebrox Posted July 1, 2011 Posted July 1, 2011 Nice one. I have not heard the ULD-III, but I still prefer the elegance of design in the ULD amp. Keep us in the loop.
Art Vandelay Posted July 3, 2011 Posted July 3, 2011 For those interested. I have built several MK2 versions which are identical to the MK3 apart from the bias generator and a few minor changes to the input and output filters. As an owner of the original ULD I can also say that sound quality from the new versions is better but only if you take time to select and match components. A much higher level of performance is obtained if you do the following substitutions / mods: Drivers - Toshiba 2sa1930 / 2sc5171 VAS / CCS - Toshiba 2SC3423 / 2SA1360 Beta enhancer (VAS) - 2SC2240 Current mirror - MPSA-18 CCS (LTP) - 2N5087 Mills non inductive PA emitter resistors (0.18 ohms) Use silver mica compensation caps and change from CMC to TMC + CMC compensaton (even better than 2 pole comp) TMC values: c1 = 390pfm c2 = 68pf, R = 2k2. CMC = 10pf Ues black gate input c cap and Elna Silmic 220uF fb cap. Insert 22 ohms degeneration into the VAS emitter and also use 1x Intersil 6 hole ferrite former as a ferrite bead (resistor lead through one hole). This is to prevent rf induced instability. Reduce the VAS BE collector resistor from 22K to 10k. Lower the VAS BE emitter from 2K2 to 1K. For mk2 version Insert a 10R resistor into the NLJ diode string with 100R trimmer in parallel. Set DC bias to 180mA Re route the driver emitters away from the output node - as per mk3 version. I am using dual PSU 's and 2x 500va Antrim transformers and 4x 40,000uF of rail capacitance. SQ is really excellent when you get everthing right. The bass is dynamic and rock solid, the mids are very detailed and the treble is detailed but sweet. I have compared this to many commercial power amps under 5k and so far none have come close.
Cyber_Murphy Posted July 3, 2011 Author Posted July 3, 2011 Welcome aboard Art!! Hope you enjoy your time here on sna.. This thread is about the Ultra-LD MK1.. But, You can post your tweeks on the Ultra-LD MK 3 thread, which is about the MK3 (and comparisons with mk 2 as well) Cheers, CM
Meganinja Posted July 3, 2011 Posted July 3, 2011 Hi I am interrest in comparing SiliconChip ULD and SC classA , keep watching this space . Regards
Cyber_Murphy Posted July 4, 2011 Author Posted July 4, 2011 Ok,, Since this power supply uses those nasty IC voltage regulators, my next task was to work out a method of shielding the power supply.. I got some aluminium cut to size, which only cost $20,, and I spent yesterday ‘knocking up’ a couple of power supply enclosures.. These will go inside the amp case and sit over the top of the power supply.. [ATTACH=CONFIG]33861[/ATTACH] [ATTACH=CONFIG]33862[/ATTACH] [ATTACH=CONFIG]33863[/ATTACH] [ATTACH=CONFIG]33864[/ATTACH] I will need to drill a couple of holes each side for the wires. I will bolt it into the amp case without the lid on,, that way I can set it up correctly and put the lid on last.. I'm not sure whether it's sufficient that this enclosure is grounded via the amp case when screwed in position, or if it needs it's own Earth wire running dierctly to the 'Earth stud'.. Anyone?? Ta CM
Art Vandelay Posted July 4, 2011 Posted July 4, 2011 Ok,,Since this power supply uses those nasty IC voltage regulators, my next task was to work out a method of shielding the power supply.. I got some aluminium cut to size, which only cost $20,, and I spent yesterday ‘knocking up’ a couple of power supply enclosures.. These will go inside the amp case and sit over the top of the power supply.. [ATTACH=CONFIG]33861[/ATTACH] [ATTACH=CONFIG]33862[/ATTACH] [ATTACH=CONFIG]33863[/ATTACH] [ATTACH=CONFIG]33864[/ATTACH] I will need to drill a couple of holes each side for the wires. I will bolt it into the amp case without the lid on,, that way I can set it up correctly and put the lid on last.. I'm not sure whether it's sufficient that this enclosure is grounded via the amp case when screwed in position, or if it needs it's own Earth wire running dierctly to the 'Earth stud'.. Anyone?? Ta CM If the objective is to create an RF shield then bolting it to the case is best Make sure you also connect the star earth points on each amp pcb to the case via 10n MKT caps. FWIW, the aluminium will do nothing to protect against magnetic induction - If that was your objective. av
Cyber_Murphy Posted July 4, 2011 Author Posted July 4, 2011 If the objective is to create an RF shield then bolting it to the case is best Make sure you also connect the star earth points on each amp pcb to the case via 10n MKT caps. Intersting idea.. I usually don't like messing around with Grounding,, but what do you have in mind? Can you draw a circuit to show what you meant.. The amp modules don't connect directly to ground,, they connect to the power supply, which is then Earthed/Grounded.. FWIW, the aluminium will do nothing to protect against magnetic induction - If that was your objective. Doh! I just assumed something conductive that would make a good (electrical, low resistance) path to ground.. Lots of devices have aluminium cases/enclosures?? Ta CM
Cyber_Murphy Posted July 4, 2011 Author Posted July 4, 2011 Next I'm planning the layout inside the case.. Since I had 2 of these amps, I am going to use the original case and heatsink for the mono blocks.. This is what an original Ultra-LD MK1 looks like (from the net). Quite "busy" with lots of wiring and additional circuit boards!! [ATTACH=CONFIG]33886[/ATTACH] And this is my proposed layout.. My aim is to keep the power supply as far away as possible from the amp module, and have a 'minimalist' approcach with wiring.. [ATTACH=CONFIG]33887[/ATTACH] [ATTACH=CONFIG]33888[/ATTACH] Cheerrs, CM
Art Vandelay Posted July 4, 2011 Posted July 4, 2011 Next I'm planning the layout inside the case..Since I had 2 of these amps, I am going to use the original case and heatsink for the mono blocks.. This is what an original Ultra-LD MK1 looks like (from the net). Quite "busy" with lots of wiring and additional circuit boards!! [ATTACH=CONFIG]33886[/ATTACH] And this is my proposed layout.. My aim is to keep the power supply as far away as possible from the amp module, and have a 'minimalist' approcach with wiring.. [ATTACH=CONFIG]33887[/ATTACH] [ATTACH=CONFIG]33888[/ATTACH] Cheerrs, CM All good but the additional screening is really not going to make things much better. Keep the rail and ground return leads short and bundled together for best performance. It's all about minimising magnetic fields generated from the large signal currents flowing through the supply rails. Bundling the supply cables can 'cancel' the fields and minimise induction into the LTP and VAS. This is where the MK2 and MK3 are better due to the PCB layout. The extra compartment in the MK1 case is a good idea though. Being steel the divider will provide magnetic shielding from the transformer + the peak rep diode current generated fields. I've attached pics of an SC ULD MK2 I built for the next door neighbour. It's simple but works well. [ATTACH=CONFIG]33890[/ATTACH][ATTACH=CONFIG]33891[/ATTACH]
Art Vandelay Posted July 4, 2011 Posted July 4, 2011 [ATTACH=CONFIG]33898[/ATTACH][ATTACH=CONFIG]33897[/ATTACH][ATTACH=CONFIG]33896[/ATTACH][ATTACH=CONFIG]33895[/ATTACH][ATTACH=CONFIG]33894[/ATTACH] 2 box version of the MK1. Transformers and surge limiter are in the bottom case
Cyber_Murphy Posted July 5, 2011 Author Posted July 5, 2011 [ATTACH=CONFIG]33898[/ATTACH][ATTACH=CONFIG]33897[/ATTACH][ATTACH=CONFIG]33896[/ATTACH][ATTACH=CONFIG]33895[/ATTACH][ATTACH=CONFIG]33894[/ATTACH]2 box version of the MK1. Transformers and surge limiter are in the bottom case Looks great Art!!
Greg Erskine Posted July 6, 2011 Posted July 6, 2011 Hi Art, Even though I don't know you, those amps of yours look very familiar. Regards
Art Vandelay Posted July 6, 2011 Posted July 6, 2011 Hi Art,Even though I don't know you, those amps of yours look very familiar. Regards What. My ideas have been stolen already?:nana
Cyber_Murphy Posted July 16, 2011 Author Posted July 16, 2011 It's taken ages,, but I have finally finished 1 mono block.. As usual, I only seem to get an hour here and there to work on this project,, so it's taking a while, but I'm getting there I'm half way there!! To save myself hassles, I used the original case and heatsink that come with the stereo amp kit, with some slight alterations.. My aim was to have the power supply as far as possible from the amp module. I also wanted to sheild the power supply, which I did by making an aluminium cover, and by using the old 'back plate' to make 2 compartments within the case.. Also I wanted to have input cable, and speaker cables, exit the case at right angles to the board and not cross or run adjacent to any other wiring.. [ATTACH=CONFIG]34219[/ATTACH] [ATTACH=CONFIG]34221[/ATTACH] [ATTACH=CONFIG]34217[/ATTACH] [ATTACH=CONFIG]34218[/ATTACH] [ATTACH=CONFIG]34220[/ATTACH] Once I finish the second one, I will be able to perform a proper listening test.. Until then,,,, mono Cheers, CM
Cyber_Murphy Posted July 17, 2011 Author Posted July 17, 2011 I don't think you have enough amps CM! Yeah I know... i promise I'm never making anymore amps!! I have about 5 or 6, plus some I've bought too.. These will compliment my Class A's nicely in an actvie biamp arrangement.. I had a few hours today to work on the second mono block,, got most of the case preparation done,, might hopefully be finished by the end of this week..!! Cheers, CM
Paul Spencer Posted July 17, 2011 Posted July 17, 2011 Do you use the A500 amps? What are you going to do with them all? Actually I have quite a few amps. 3 stereo power amps and a 4 channel for some active surrounds. If I carry out one of my my complex ideas for the next mains then I will actually need another 2 channels. It quickly becomes nutty!
Cyber_Murphy Posted July 17, 2011 Author Posted July 17, 2011 (edited) Do you use the A500 amps? What are you going to do with them all?Actually I have quite a few amps. 3 stereo power amps and a 4 channel for some active surrounds. If I carry out one of my my complex ideas for the next mains then I will actually need another 2 channels. It quickly becomes nutty! As you know, my A500's are modded a fair bit, so I can't sell them as "Berhringer A500's",,, so I gues I will 'put them away',,, somewhere,,, out of the hall-way I suppose Actually, once this project is finished, I'm going to sell off a lot of my audio stuff and do a big clean out!! Ta CM Edited July 17, 2011 by Cyber_Murphy typo
Cyber_Murphy Posted July 22, 2011 Author Posted July 22, 2011 Ok, I have finally finished converting my Ultra-LD into mono-blocks!! I had a quick listen to them last night, and they sound great.. More detaied summary, plus a comparison to my Class-A's, to come down the track as I put in more listening time.. Since I had 2 Ultra-LD's, I just used the original cases and heatsinks.. I also used custom made transformers.. This means that I have another 2 modules of Ultra-LD, including transformers, tucked away for a "rainy day" :-) Some pics.. [ATTACH=CONFIG]34385[/ATTACH] [ATTACH=CONFIG]34386[/ATTACH] [ATTACH=CONFIG]34387[/ATTACH] Cheers,, CM
Cyber_Murphy Posted July 23, 2011 Author Posted July 23, 2011 Well done C-M! They look really professional Thanks.. Up close they're a bit "rustic",, but i like that DIY look :-) So far, my impressions are that in 'mono block' form, they're much faster to respond to transient burst, and much tighter..Clarity is fantastic and they're a lot quieter than i remembered them in stock form.. At this initial stage I think my Class A's have more air/space around the instruments, but definately noticed the class A's lack something that these do much better, and that is mid range loudness and speed.. More to come.. Cheers,, CM
Cyber_Murphy Posted July 28, 2011 Author Posted July 28, 2011 Just to finish off this project, I will say that these amps sound amazingly good! The original description for this amp (and the Class A amp) states these amps punch well above their weight, and that they are comparable to amps many times the price.. IMO, this is quite true,, particularly now as I have made them into mono-blocks with nice locally custom made transformers.. From these last 2 amp projects,, I think from now on I will only go for mono amps.. I can't imagine ever sharing the same psu and case for both channels.. The results are much better,, as is the minimalist approach, Eg, no speaker protection or soft start, no volume or level adjust, no routing the mains switch to the front of the case, or long runs of signal, speaker, or mains cable inside the amp,, in and out as quick as possible!! The idea of this project was to get ready for a good active bi-amp arrangement. But also, to compare directly with the Class A amps I had made previously. This is what I've found after a few days of hot-swapping both amps (which is quick and easy with my DXC and utilizing the Bi-wire terminals on my speakers) Class A: -Sharper, cleaner, and louder, High frequency playback -Wider stereo imaging -Better space & blackness inbetween instruments -More detail, Eg, hear spit hitting the microphone and finger tips scraping along guitar strings (maybe due to its pronouced HF playback, but enjoyable nevertheless!) -Vocals a tad squelchy, maybe due to "louder HF" playback? Ultra LD: -Better vocals Eg, more forward, but smoother realistic vocal presentation -Punchier, tighter & louder mid bass (on the Class A, sometimes I couldn't hear the subtle mid-bass tones on certain songs unless I turned it right up) -Sound stage not as wide, imaging not as pinpoint -Seems to have less space & blackness inbetween instruments (maybe because it's louder and 'fuller'?) In summary, I would say the Ultra-LD has Bigger, fuller, and a more complete natural sound,, but sacrifices a bit on space, sound stage and detail, in comparison to my Class A's.. I think this will result in an excellent combination for a bi-amp arrangement! Where the Class A will have execellent HF clarity, cleaness, and detail.. And the Ultra-Ld to provide excellent mid range and mid-bass repsonse, and provide the majority of the vocals.. Cheers CM
Meganinja Posted August 1, 2011 Posted August 1, 2011 Hi Thanks CM alot for the review of ULD versus ClassA , very useful information for me , as I also want to bi amp my speaker . Regards
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