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回覆 (612): Apex PA 04
Thanks. You are always welcomed.  
The night before, master Yu was here and gave very positive comments on the Apex.
回覆 (611): Apex PA 04
Congratulations Derek !!  
Must see it before your wine cellar spills >.<
回覆 (610): Apex PA 04
My search for the ultimate power amp to drive the Dunlavy has come to an end.  
Near future is only to have a proper chassis to house the components with no more wires flying around when the last piece of puzzle arrives. This Apex, another power op, surpass all the others that I have tried by quite a margin esp when it comes to speaker control. It can deliver 200w 8 ohm, 400w 4 ohm with a single chip. Max current is 20A.
回覆 (609): Dunlavy SC4A
Pass labs SS amps has one of the lowest damping factor ( DF) in the business  
Yes, damping could be the reason why Pass Labs doesn't go well with Dunlavy,not to say tube amps fail miserably. In both situations, sound was 唔精神, 十足未上電
回覆 (608): Dunlavy SC4A
Forgot to mention, I doubled the output device only, without up scaling the power supply proportionally. So, there is room for further improvement. Anyone out there know where I can get off the shelf high power (approx. 1KVA), low secondary voltage (22V AC) power transformer? Help would be appreciated.  
Now, the soul of my system, the Dunlavy SC4A. Every move in the past since its arrival has been efforts trying to get the most out of this Stereophile Class A speaker. All you read on the net about its accuracy, coherence, neutrality are true. Simply put, this is MY best speaker ever. It is a pity both the man and the company no longer exist.
回覆 (609): Dunlavy SC4A
Sorry, the Rotel RB1090 Damping factor (20Hz–20kHz, 8 ohms) is 1000
回覆 (608): Dunlavy SC4A
Rotel RB 1080, 200W X 2, very conservative in power rating. Neutral sound, pretty much like a poor man Pass Labs X250.5.  
Calling the Rotel 1080 a poor man ( "wise man" be a better term) Pass labs X250,5 is same as saying the latter is overpriced. Good point indeed!  
In fact, since Nelson Pass no longer owns Pass labs, and with rising production cost and a shrinking market, I am afraid their best days may be over ( same goes for ARC). Also the reason their older products are now highly desirable, the X 0.2 and Xono still rank at the top.  
The other problem is Pass labs SS amps has one of the lowest damping factor ( DF) in the business, I recall the X350 rated only around 80 in damping factor where similar amps be north of 300! Useless amp to drive multiple big woofers.  
ps: Btw, the Rotel RB1090 (early UK version with black face : dual mono 380W 8 ohms, 700W 4 ohms / damping factor 400 ) most likely will bitch slap your Dunlavy to complete liberation : - )  
pss: Rotel RB1090 merit: TAS Golden Ear Award ( HP era) / TAS top 10 amps of this Century / Stereophile Recommended since Birth
回覆 (607): Dunlavy SC4A
Having tried out the above, I accidentally ran into gainclone. I was impressed by how simple the amp is, and the sound being so transparent and neutral. That was a LM3875, exact chip the 47 lab gainclone employed.  
With so little power, it of course couldn't push the Dunlavy to full blossom, so I diyed my own LM3886, a different chip which is spec to have more power. Sounded more powerful for certain, but not in the same league as the LM3875.  
So I surfed the net for more options. I picked Burr Brown OPA 541, which could deliver 5 amperes continuously. This do resemble the sound of the Texas LM3875, with better body and more meat, probably due to larger current. Not the end of the journey yet, but at least it can now drive the speakers reasonably well, and I don't look back at the Vincent D150 anymore.  
Yesterday, I just installed a second pair, paralleling them ie. two chips per channel. More powerful definitely, may be a slight diminish in refinement. Just allow them to burn and see how it goes. Final plan is likely to have six chips per side, bridge + parallel for ultimate power 300W 8 ohm, 600 ohm 4 ohm. This should take a few months to accomplish.  
Friends are welcome to witness the gainclone + Dunlavy and judge it yourselves.
回覆 (606): Dunlavy SC4A
Thanks for asking! Should have update you gentlemen for my recent process, my apology.  
The Dunlavy SC4A are well burned in by now, I just love every single minute of its company, absolutely no complain. But my diy project is progressing pretty slow. To recap, you guys might still remember me talking about those gainclone power opamps and looking for the ultimate partner for the speakers.  
For the past year or two, since the arrival of the SC1, little brother of the Dunlavy series. I have been searching for a proper power amp, so as not to embarrass the rather splendid speakers. Short summary below is of course very subjective, pls don't take it serious, as we all have different preferences.  
Hafler DH200, nice in every way and very musical. I just enjoy music coming from this vintage amp. Only problem is, resultant sound is a bit inclined to old solid state gear. I bet it would be a great amp mating with horn, but I haven't tried.  
Rotel RB 1080, 200W X 2, very conservative in power rating. Neutral sound, pretty much like a poor man Pass Labs X250.5.  
Sony Vfet, can't recall the model no., triode sounding but under powered. You have to hear to believe that there are solid state amps so liquid and smooth, wonder why so little people noticed its existence.  
Naim NAP 150X, I finally witnessed its PRAT, absolutely fantastic, with neutrality in doubt, plus it lacks both end extension preventing my speakers from reaching higher scores. Not to say, it cannot drive the SC4A to orgasm. One look at the price tag of high powered Naim power amp, I almost faint.  
Vincent D150 hybrid, certainly not the best amp even after my little Mod. At least this was what I've been listening to in the past two years.  
Pass Labs X350.5, thanks to Patrick for lending me this all round high power amplifier. It is great, but together with the Dunlavy, sound was polite, and not vivid.  
MFA M200B, the only tube amp that I have tried. ???? this bettered every amp mentioned above when working with Maggie, but when it comes to Dunlavy, even after tube rolling, it immediately becomes bottom of the list. Pls don't ask me why, as I have no intention to further dig out. Perhaps, tube doesn't work well with Dunlavy.  
回覆 (605): Dunlavy SC4A
Derek, what is going on with your Dunlavy ?
回覆 (620): Gain Clone
Please see my description on T amps..  
Not every 3116 is made equal...need to design the pcb right..with right components.(^_^)""
回覆 (619): Gain Clone
I beg to disagree Tamp or 3116/8 can out run a proper tube amp.  
I have been playing with T2024 and 3116 for some time. Probably built no less then 10 over last few years.  
They are all superb in value and very stable work horse but they all seems to share a common characteristics which can be a plus to many or minus to some (including me).  
These amp usually have amazing driving ability and can be pleasing to ears with its slight roundness, yet it has a subtle compressed dynamics. It makes many details stand out but at a disproportional way. This makes the overall sound kind of flatter than I prefer and perhaps details "too clear" at low level.  
Maybe it is just me thou. You know, I always have bad hearings.  
回覆 (618): Gain Clone
GC does sound good...perhaps as you said with resemblance like OTL tube and VFET..  
Recent advances in digital amps designs, particularly with those TI chips are quite fascinating... how about sounding closer to triodes? Thats how some would describe.it..  
After hearing my Wiener amp with a tda3116 chip on board side by side against some dht set amps driving hi eff.speakers....no longer will I crave for better tube amps from now (except tube pre), though am keeping my 45 SET and 45 PP...  
Actually solid state amps are much more interesting to.me...Satri current amp, Kaneda IVC, Pass VFET...etc..  
回覆 (617): Gain Clone
What you just described is an..opamp... (^V^)  
And indeed its a power opamp (^_^)  
It was designed as a low cost thing for lo fi TV, portable devices, etc..  
But if you look at the internal circuit.though, its hitech (^_^)
回覆 (616): Gain Clone
CFT, pls keep sharing with us your experience on GC and Ti amps.  
My wild guess is the first day when they decided to develop the GC, what the engineers had in mind is to keep it as simple as possible with minimal supporting components, or you might say they've incorporated everything they possibly could within the device. So, high PSRR, no need for big reservoir cap, no need for exotic filter. Can do without cap in the signal path, though the datasheet recommended it in the input to avoid DC from the preceding stage. All boils down to just a few resistors:  
one input R  
one input loading R  
one output R  
two feedback R  
one mute R  
only the output resistor need power handling, 3W can do. The rest can be 1/4W rating ones.  
And of course a very simple power supply to go with. Put everything together, and the whole thing is already a power amp. One could even include a volume control, adjust the gain accordingly with different value feedback resistors and turn it into an integrated amp. So genius.
回覆 (615): Gain Clone
I have been using GCs for a decade..in my Linkwitz system.., and so I know..its with the shortest path feedback caddock resistor directly on the leads of the lm3886, and only two 1,000 uf filter caps for the power supply on mine..(^_^)  
T amps have problems in mid hi...no..no..its history.. the ti chips came out not long ago, should try that out...if executed right, its a big margin of improvements, not subtle, over the highly modded 300b I heard or vt25 with Tango cows, etc...
回覆 (614): Gain Clone
To make things clear, the gain clone has nothing to do with those class D, T or tripath digital amps, it is an analog amp.  
For those who are interested, there are lots of info on the net. One can find the circuitry inside the op amp in its datasheet.  
All kits and commercial products come with a tiny PCB for the op amp together with the peripheral and supporting components. That's not what I need! Call me crazy, I want hard wiring or direct soldering, not easy with those pins/legs that are so close together, tough but can be done.
回覆 (613): Gain Clone
CFT, thanks for your info to make things clear.  
Personally, I don't like those Tripath, T amp, D amp. Could be a matter of taste, I am not sure. I know a lot of people love them, and there are always new chips and improvements. Perhaps I should listen to the latest version and witness it myself after years of development.
回覆 (612): Gain Clone
GC in the diy world has faded completely since the tripath chips came along...a few years back.  
Now those t amps (with tripath chips) are also history...  
These days the Ti chips rule...  
You ought to hear a tpa3116 amp perform. taobao has it for a mere rmb50..  
As a reference, the wiener amp with a tpa3118 chip on board has replaced Welborne's VT-25, 300B, 6c33c, etc..
回覆 (611): Gain Clone
When 47 labs introduced their gain card, they declare that it has the shortest signal path on earth. True at that moment. Now we have a bunch of small companies like Audiovector, Clone Audio providing kits and assembled units that might have even shorter paths.  
Having heard one incidentally, and the sound was very promising. The transient, the clarity, the neutrality. To describe it verbally, the damn thing sounded like a mix of OTL valve and Vfet.
回覆 (610): Gain Clone
Back to the title.  
Some of you might have heard or even possess the 47 labs gain card. Gain clone is just another name of the output device. In simple terms, an op amp that can deliver power and current that can drive the speakers directly.  
It was developed during the 90s, for TV audio section and mini combos, where a simple solution to signal power is required in hope to replace large PCBs with lots and lots of discrete components. It was probably another cut corner approach in mind to begin with. Turn out they have a complete power amp all packed in a small device size of that of a bipolar transistor. In the end, I have no idea whether they ever succeeded in the mass media or not, since these days class D amps and switching power supplies seems to be the norm or standard.
回覆 (609): Gain Clone
Looks like I need to get more TTs, arms......  
Bet you already have a lot, just scattered here and there, without you even noticing. Still remember the Lenco downstairs?
回覆 (608): Gain Clone
>......there's eleven turntables all armed <  
Looks like I need to get more TTs, arms....... :-(  
回覆 (607): Gain Clone
The gentleman is really serious. Our master did bring along his favorite CD, not to mention 20LPs. One can imagine this is heavy for someone his age and built.  
Highlight of the day would certainly be Wher's place, where there's eleven turntables all armed. Yu walked round the place, starring at the setups one after the other, with Wher touring him around. We listened to his records, and towards the end, when it's time for dinner, Alan Yee said: Later, I still have a few recordings I love to hear.
回覆 (606): Gain Clone
Mr. Alan Yee (master Yu) retired April this year. Of course, nothing could stop this hi fi 精 from continuing his audio journey. He is occupying himself with of sorts hi fi gatherings and events.  
This Wed, he came to Chai Wan 踩場. First my place, then Alan's, last Wher's den.  
Those who have pics, pls help post them cause my company's computer won't allow me to download from my cell phone for security reasons.  
The main purpose of his 踩場 was, he overheard that I diyed a gain clone power amp which he got no idea what it is all about and would to witness it himself.
回覆 (605): Gain Clone
回覆 (604): Dunlavy SC4A
a pair of Bryston 7B  
Good, but my heart goes to Pass Labs X350.5
回覆 (603): Dunlavy SC4A
Whenever I think of high power, I regret not getting a pair of Bryston 7B when it was available and reasonably cheap back then....  
回覆 (602): Dunlavy SC4A
Vincent reveals the under power of Hafler, next question would obviously be whether the former has sufficient power to do justice to the SC4A?  
After no less than 200 hours of run in, boom and lack of control in bass are gone. Yes, I am running the speakers 24/7 non stop till today with the now TV decoder > optic fiber > Wadia 151 digital amp. Give it another 4 weeks, and the Dunlavy should be fully burn in. Only then would I pair it with a 300W x 2 or more power amp. Right now may I just forget about the rest and enjoy music.
回覆 (601): Dunlavy SC4A
The Hafler Dunlavy combo was in fact not bad at all, music is enjoyable, proofing it again a giant killer. I couldn't hear shortage in any area, but would like to see better neutrality and transparency. In fact, if I were using a horn system, I might pick the Hafler. I just wish those who advocate the beauty of class D amps can be around to witness it.  
Now the modded Vincent in place, transparency is back together with better extension in both extremes. Music wise, it is on par with the Hafler, at least I don't miss the Hafler, and soundstage is wider and bigger with more details at the back ground. Surely, one reason for the above findings is power, the Vincent's power trans size is double that of the Hafler, not to say the number of pairs of output device and capacitance of the reservoir caps.  
回覆 (600): Dunlavy SC4A
Hafler Vs Vincent  
philips cd 960 with 1541 single crown + tube output (output opamps replaced)  
spot welded passive preamp with direct soldered interconnects both in and out  
Hafler DH200 / Vincent D 150  
Dunlavy SC4A  
The Hafler needs no intro, like Dynaco, it was the power amp of poor men in the 80s. As for the Vincent (German company with manufacturing in China), the D150 was their first power amp in the early 90s, featuring 150W x 2, hybrid with tube input and SS (bipolar) output.  
The Hafler is a stock unit, and the Vincent was modified, mainly component replacement with dale, Wima and Philips BC in the tube section.  
回覆 (599): Dunlavy SC4A
Do let me know. Vincent is probably a more warm sounding amp and better match bookshelf type. Hafler should be clean and "song".  
SC4A is 92db. May work. :-)
回覆 (598): Dunlavy SC4A
Halfer? bullet proof power house! For SC1, the Vincent is definitely better in every way except punch and swing. Would try it on the SC4A and see how it goes this time. Thanks for reminding me.
回覆 (597): Dunlavy SC4A
Yes Ben, the sub was there only for the SC1. Now that I have the SC4A, subs are longer necessary.
回覆 (596): Dunlavy SC4A
Somehow my gut feeling is that you don't need that many things. Just a SC4A and a high power honest workhorse class AB amp can do the job and shake your ceiling down. ;-)  
A few names I can think of -  
Parasound, Bryston, NAD and hey you already have a Hafler!! (Tried that?)
回覆 (595): Dunlavy SC4A
Belief and myth  
John Dunlavy, the designer only believe in first order filtering, when it comes to crossover to get the best impulse response, an engineering term I hardly know. In simple terms, send a pulse to the drivers, that pulse should be reproduced with minimal decay and resonance.  
Looking at the spec of any Dunlavy speakers, you will never find the crossover point. Rumours are, since no two drivers are the same, Dunlavy sent every pair into the anechoic chamber, made measurements and fine tuned the crossover frequency to meet his requirement.
回覆 (594): Dunlavy SC4A
The good part continues  
The high. With the Dunlavy SC1, I needed a pair of visation ribbon tweeter in parallel to augment the treble, otherwise there was a little lack of extension. Surprisingly the SC4A, employing the same tweeter of the SC1, treble extension is no longer a problem.  
Knowing nothing on speaker design, a wild guess was a pair of three way speakers, the Xover point for the tweeters can be pushed higher. Working under the condition handling less mid, tweeters should perform better, focusing purely where it work best.
回覆 (593): Dunlavy SC4A
Side story of the SC1 + sub woofer  
Thanks for sharing, Ben.  
Do agree the sub has to be placed in front of the satellite speakers, and a digital electronic Xover making life easy with the delay function.  
The sub started off with a built in plate amp + Xover, sounded sluggish and muddy. I disconnected the built in electronics, used Bryston 10B + Hafler DH 200 to power it, immediately everything was already a mile ahead, though still a bit slow. To take it further, I added two 10" open baffle. Last I built a passive filter to replace the Bryston. Things got settled, and I was enjoying them every single minute until the arrival of the SC4A.
回覆 (592): Dunlavy SC4A
If we are to add sub into a system, as well get a digital crossover and put the sub in front of the Dunlavy and use delay function to time align it. This can be fun to try out.  
(Afterall, normal built in subwoofer crossover usually has a lesser slope and doesn't not cut clean. This can polute the upper frequency.
回覆 (591): Dunlavy SC4A
Derek, you certainly need a bigger, much bigger, amp.! :-)  
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