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回覆 (383): please dont forget 26th July concert
I uploaded lots of photos and info about my recent SV811 amp. The only response I got was from Derek2A3. So, my assumption is that either you have no interests on DIY or you have a bit of interests but you don't care enough to response. Either way, if a relationship is to work, it cant be single ended. Right! And you cant say I haven't tried. Right?  
 
Its very heart broken to me more than you know but what else can I do. Maybe people are hiding or just not interested in the kind of bull shit I created. Even so, say something lor. This forum is free. Comment a little lor! Make this forum a bit more human please. Share with me with your thoughts lor! WHAT SO BIG DEAL THAT STOP YOU FROM COMMENTING AR!  
 
So, here I am, that's the very end la. Its boring and no fun. Let just say my creation was bullshit and never an interest to you all but to Derek2A3. OK!  
 
Well,........ all the best and no hard feeling. As I said, my lost more than yours, I am sure. Thanks to the host/forum owner Mr Wong Sir.  
 
All the best!  
bobui
16-07-22
00:48:55
回覆 (382): please dont forget 26th July concert
You know what, guys! To make things more easy for everyone. Here is what I have to say and propose.  
 
The thing is, I already tried to pulled myself away from a lot of gathering and HH in recent months to avoid conflict. Turn out that my words and blow water talk seems less than comfortable for most here at 1pk. Right!  
 
So, my proposal is....... I leave completely and off the grid la. Meaning, no more 1pk la. For those who got my number, I am as of usual to respond and bull shit around.  
 
Thanks to everyone at 1pk. Its my lost more than yours for sure. No worries la.  
 
All the best,  
bobui
bobui
16-07-22
00:14:42
回覆 (381): please dont forget 26th July concert
This particular recording is the first classical record I bought in the late 80s. Its the interpretation I still prefer more than the others. First come first serve ma.  
 
Don't forget A Volodos on 26th July ar! There might be some tickets left. Good luck!  
 
Enjoy! This one is right in the middle of my heart.  
bobui
16-07-15
18:08:26
回覆 (380): Final Picture of the SV811
BTW, 4V input sensitivity is on the low side.  
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Yes, is on the low side. I do not want overdrive and keep the amp working in AB1 with no grid current when using SV811-3. For the SV811-10, is inevitable that grid current will jump in well before approaching max signal. Not much I can do but to make sure the driver stage has as lower impedance as possible.  
 
4V is low but as long as the mc phono has a gain of 67db or higher (assuming the mc cartridge output is 0.002V), there should be no problem to achieve a 4V output and there usually a preamp in between with some gain also.  
 
For CD, a 4V input sensitive is not a problem la. Since CD output is 2V or above. Plus a preamp in the middle, 4V is easy target.  
 
bobui
16-07-13
16:35:16
回覆 (379): Final Picture of the SV811
Pls keep us updated on your new toys performance esp when equipped with 811-10 driving Leak.  
 
BTW, 4V input sensitivity is on the low side. Bet your preamp can handle this properly.
Derek2A3
16-07-13
15:36:25
回覆 (378): Final Picture of the SV811
Hope I hadn't bored you all to sleep with my recently published SV811 details!  
 
Here is a last closing photo of my SV811. Screen print and badge all done. The amp has been tested and running for more than a total of 12 hours.  
 
Spec summary:  
Power: 80 Watts (SV811-3), 200 Watts (SV811-10)  
 
Tube line up. 6J5, 6BX7, U19X2, SV811X4 per channel  
 
Distortion: I have not got round to measure it up with my HP analyzer yet.  
 
Noise and hum: 8mv (SV811-3), 20mv (SV811-10) measure at speaker terminals  
 
Input sensitive: 4V  
 
Feedback: via a selector switch at the rear for Zero, Low or High  
 
Weight: 192lbs  
 
Input voltage: 220V  
 
Components:  
Power transformer (output tubes): Gresham C-core, NOS from UK  
Filament transformer (output tubes): Gresham C-core, NOS from UK  
Output transformer: Sowter,  
Driver circuit transformer: Non branded UK made 70s  
Chokes: Langevin (output tubes), Stancor (driver tubes) NOS from USA  
Capacitor: Sangamo, F&T and Seimens,  
Signal Cap: Wima MKP10  
 
Cost: Since most major components are gathered long ago from various 2nd hand and NOS sources, I kind of lost count on actual spending. A close estimate if sourcing all transformers from Sowter today would end up roughly HK$28,000 (all transformers alone).  
Total cost for building an almost identical twins of today money would be roughly HKD50k  
 
 
Bye and all the best till next time la!
bobui
16-07-13
14:42:51
回覆 (377): What have I done for the last 4 years!
Build the 833 PP la, a pair can output 1.6KW  
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Wah, need a real high hand or C Fu wor! Me just an amateur. >100watts already a big challenge for me.  
bobui
16-07-11
18:38:18
回覆 (376): What have I done for the last 4 years!
Build the 833 PP la, a pair can output 1.6KW.
Derek2A3
16-07-11
17:16:10
回覆 (375): What have I done for the last 4 years!
U know what! Kong is right. The more the power the better! The PPP SV811 is now only set at roughly 80Watts in class AB1 and not only it doesn't sound rough or aggressive with the Lowther. All the very finer details just come to my ears so much more clear and the bass has never been so full and rich in my Lowther previously. Sound stage is..... so long! So much more 3D sound than any of my Single ended amps lor!  
 
Currently, the amp is with eight SV811-3 which is a lower mu triode similar to the 300B in terms of amplification factor. The B+ is set at 620Vdc. Cathode current at 65ma per valve which is roughly at 40 Watts dissipation. The SV811 can run well into 800Vdc at 80ma (65Watts max dissipation).  
 
If using SV811-10, power output can reach near 200Watts with ease but it will have to be in Class AB2. Meaning grid current drive. Not a problem with the 6BX7 la with it lower impedance high current capability. Higher power is for my Leak 3090 which carry a 15 inches woofer and in 4 ways.  
 
This SV811 amp is the most powerful amp I have built ever. In the near future, I intend to build more powerful amp. Next one coming is to complete an amp for a friend who have been in the long wait and then the TEN 6B4G per channel 150Watts amp.  
 
If all the conditions can be met with reasons, I also like to build a 300Watts tube amp using eight GM70 per channel. Crazy!  
 
bobui
16-07-11
16:54:06
回覆 (374): What have I done for the last 4 years!
Wow, hot pants and wet T shirt.  
 
You have an incorrect 20hz pic to show us?
Derek2A3
16-07-11
11:54:32
回覆 (373): What have I done for the last 4 years!
Ooopssss! Don't get over excited please. Here is a correct photo for 1 KHz test!  
 
The amp is not fully done yet. I still have to do the valve type hand print and add on a label. Perhaps, also a change into some exotic signal caps.  
 
Just like everyone of us, I am a little scare to step on the scale to weight the SV811 amp!  
 
bobui
16-07-11
10:45:57
回覆 (372): What have I done for the last 4 years!
Here is scope test 3. Input 3V. Frequency 1KHz. This got to be the most commonly tested frequency for audio amplifier. This time, if the wave is not square, better start from scratch again and dismantle the amp for recycle! A tiny bit of snake line round the edge is fine but best to perform as square as possible. No excuse la! I don't care how much you trust the scope as an indication of quality sound measure or how the scope can be so unrelated to real life music because at this frequency, the amp should have ZERO problem to reproduce the square wave.  
 
bobui
16-07-11
10:36:27
回覆 (371): What have I done for the last 4 years!
Here is scope test 2. Input 3V. Frequency 20KHz. This is the frequency limit that someone somehow set it for us all sometimes ago as the max listenable frequency from an audio amplifier which I am sorry to say I do not agree fully. I simply just cant hear anything above 18KHz. Can you? So, what is the point!  
 
Well, at least from a scope, the square wave looking more like a square. The shape you seeing is kind of NORMAL for a valve amp. Don't expect you would see a completely square wave at 20KHz from any amps la! Even if it does, its likely sound too bright and harsh for human hearing!  
 
 
bobui
16-07-11
10:24:59
回覆 (370): What have I done for the last 4 years!
Of course, a gathering would be nice. Food and drink first. Hi Fi coming 3rd lor!  
 
Here is scope test 1. Input 3V. Frequency 50KHz square wave. Square wave no longer looking like a square which is normal at this frequency. This test is mainly for stability test under high frequency. Square wave become rounded is OK and as long as here is no sudden peak or spike, the amp indicating is working stable and no ringing.
bobui
16-07-11
10:16:31
回覆 (369): What have I done for the last 4 years!
Very stylish looking, well done.  
 
Man, once burn in, you gotta arrange a gathering for our inmates to witness how this beast sounds. DHT PP, some said it is the most linear output one can have, hearing is a MUST.
Derek2A3
16-07-11
10:09:44
回覆 (368): What have I done for the last 4 years!
After four years of hard work. Here is what I have done! SV811 PPP finally singing to my ears.  
 
What can I say?  
Very hard work. Especially the many holes in the chassis, the spray hammertone and the gathering of all the major components etc which took me over four years of nonstop search and watching! Tough! Very tough! More than you can imagine lor!  
 
How does it sound?  
The one thing I have learned from this PPP SV811 amp is the importance of .........POWER. Even when I just hook it up with my Lowther, the excessive power available is ......just make everything sound so much better. Push pull direct heat triode, the king la! forget about your KT88s and Pentode lor!  
 
Whats most difficult in the making and what is most interesting during construction?  
Most difficult is surely the making of the chassis. Most interesting is the styling. I mean getting it done the way I wanted it to be.  
 
Does it worth all the effort?  
Emmmmmmmmmmmmmmmmmmm..........Well, if you got the dollarsssss. Go and buy your dream powr amp lor! For me, I have zero option but to build it myself!  
 
The circuit?  
Nothing special la. Input voltage gain stage is from a 6J5 (half of 6SN7). Phase splitter is a long tail pair DC coupling 6BX7 for its lower internal impedance and high power because the SV811 do draw some grid current. The SV811 is fixed bias with individual separate adjustment at the rear of the amp.  
 
Power output?  
I am now limiting it to 100Watts only. Can adjust to a max output of 200 watts in AB2 with SV811-10 at the expense of a bit of grid current.  
 
What are the four large tubes in the middle?  
They are rectifier tubes for the power tubes SV811. Type number is U19. Driver/voltage circuit has separate power supply from the power output SV811 tubes.  
 
How much it weight?  
I have not got round to put it on the scale yet Don't expect to carry it up the stairs even if your name is Ivan!  
 
What are the output tubes?  
Svetlana SV811-3 or SV811-10. Cannot work with old type 811A.  
 
You like?  
 
 
 
 
 
bobui
16-07-10
22:05:52
回覆 (367): Biggest SE iron I have seen
No, the transformers not mine. Is from a publicly listing site. Might be you can negotiate with the seller to be paid in UK pounds. Surely would be at least 10% cheaper!  
 
bobui
16-06-24
14:18:56
回覆 (366): Biggest SE iron I have seen
This got to be the largest pair of iron for Single Ended. Weight over 12kg each and has a primary impedance fit for 833A, 4212 or almost most transmitter tubes.  
 
Anyone interested, I can send over the link to you for direct purchase.  
 
bobui
16-06-24
13:30:39
回覆 (365): Preview SV811
your amp would automatically inherit the WE signature sound, trust me!  
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Father and Son talk:  
Father: My Son, you fast approaching 25 soon. Have you thought about what you want to do for a living?  
Son: My Dad. Of course, I thought about it a lot. I want to be an Hi Fi sales.  
Father: You what???? Hi Fi sales. Are you kidding me? How about a banker, IT, Logistic or Civil Engineer. These are all hot jobs.  
Son: NO, my dad. I want to be a Hi Fi sales.  
Father: Exactly what you want to sell???  
Son: Western Electric stuff.  
Father: There is no more Western Electric. They just don't make them anymore, right?  
Son: Exactly  
Father: There is no standard or reference market price for WE stuff. Its a fish market out there, right?  
Son: Exactly  
Father: WE stuffs are mostly not measured and created for today audio specifications. A complete lack of tests and measure standard.  
Son: Exactly  
Father: Its a niche market hidden away from high street audio shop. Hardly any marketing or salesmanship.  
Son: Exactly  
Father: Many WE stuffs are not even labelled or come with any identification. People simply have no way to verify them.  
Son: Exactly  
Father: All these WE stuffs. Are they really that good? Are they what they claim to be even after 50 years from their production date? No one knows, right?  
Son: Exactly  
Father: I just don't get it!  
Son: Exactly. To you audio is a toy where you spend your hard earned cash. For me, I am going to make lots of money from it. You have some WE cables hidden away, right?  
Father: Yes, but I am not sure if they are really WE.  
Son: Exactly  
 
bobui
16-06-23
12:55:37
回覆 (364): Preview SV811
there are two good looking blond gals only recently moved on upstairs.  
_______________________________________________________________  
 
Pls invite them for party  
 
 
With a touch of WE, Oh, I am sure there will be no lacking of lush and mellow mid range.  
_____________________________________________________________  
 
Certainly. With whatever parts, components, wires, or even just the logo of WE, your amp would automatically inherit the WE signature sound, trust me!
Derek2A3
16-06-23
11:08:56
回覆 (363): Preview SV811
But there's not much you can do now, right?  
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No, absolutely nothing I can do now. Perhaps, I invite a few strong hands to come over to stay my den 24/7! Ah, just came to my mind that there are two good looking blond gals only recently moved on upstairs.  
 
This picture is for the die hard Western Electric camp! With a touch of WE, Oh, I am sure there will be no lacking of lush and mellow mid range. A killer touch, Right?  
 
The many holes below the meter is where I would be sticking in a screw driver for the eight SV811 bias adjustment.  
 
bobui
16-06-23
10:45:31
回覆 (362): Preview SV811
Moving, not lifting, a 150lb beast is already terrible.  
You will soon find out, may be limage can shed some light here.  
 
And this is no commercial amp.  
This your diy project, you still have to do soldering and make minor adjustments here and there every now and then.  
Four 50lb chassis would certainly make life much much easier.  
But there's not much you can do now, right?
Derek2A3
16-06-23
10:26:57
回覆 (361): Preview SV811
You should have divided that into 4 chassis.  
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I have built larger single chassis and 4 chassis amps in the past but never been with a single chassis weighting this much. A real challenge to my physical ability lor!  
 
Since each tube has its own filament supply. There would be 28 wires running across two chassis if I were to separate the power supply from the main amplification board just for the filament. Total inclusive of B+ and individual bias for the 8 power tubes would bring the number of wires to as many as 50 plus!  
 
And to be frank, I do prefer separate power supply in a two chassis format than mono blocks. The only advantage I can think of for mono blocks is the possibility of shorter speaker cables.  
 
Below picture is the top plate of the amp where the valves sit on. At the bottom of the picture on each side is the driver stage power supply transformers (EI). Further up in the middle is the driver stage smoothing chokes. The two large rectangular shape transformers are filter chokes for the high voltage B+. Behind them are the four driver tubes.
bobui
16-06-23
10:08:28
回覆 (360): Preview SV811
Total, I would say around 150 to 160Ibs.  
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You should have divided that into 4 chassis.
Derek2A3
16-06-23
09:29:17
回覆 (359): Preview SV811
just curious how heavy the thing is?  
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High voltage B+ transformers X2, B+ chokes X2 together with the Output transformer X2 approximately weight = 70Ibs. These probably contribute to around half of the overall weight.  
 
The remaining eight smaller transformers weight in around 30 to 40Ibs. Plus all the components and the very light chassis (roughly 10Ibs max). Total, I would say around 150 to 160Ibs.  
 
Much of the weight savings come from the light chassis. Otherwise, it could easily end up over 200Ibs.  
 
I suspect Ivan alone can lift it up single handed. For normal human, four hands would be best.  
 
bobui
16-06-22
18:30:49
回覆 (358): Preview SV811
just curious how heavy the thing is?
nicknick
16-06-22
16:03:44
回覆 (357): Preview SV811
Looks HOT !!!  
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My CEO said, don't like the SV811 wor! Its larger than the living room air con!  
 
bobui
16-06-20
08:28:49
回覆 (356): Preview SV811
Looks HOT !!!
daiwok
16-06-18
15:24:06
回覆 (355): Preview SV811
Encouraging, thanks!  
 
Yes, you might be right. I am a little concern about ventilation too. Especially the two SV811s that sits very close between the transformer cases.  
 
Well for a start, this amp is likely ggoing to be switch on from June to sept lor!  
bobui
16-06-18
10:59:19
回覆 (354): Preview SV811
Absolutely gorgeous! I especially like the yellow grey color match. Well done, again.  
 
Just one comment. I am afraid, you might have heat problem.
Derek2A3
16-06-18
10:28:31
回覆 (353): Preview SV811
Oh, sorry. Meant to post this one too which offer a stronger perspective on the size and shape of the SV811.  
 
Still too tiny for some, right?
bobui
16-06-18
10:13:48
回覆 (352): Preview SV811
One more front view for now!  
 
bobui
16-06-18
09:44:09
回覆 (351): Preview SV811
Here is a preview of my humble creation. The PPP SV811. Its about 80% done as of today.  
 
The middle four tall tubes with caps are U19 rectifier for high voltage B+. Either sides are four SV811 for each channel.  
 
Right behind the four U19 are two large chokes for high voltage B+ filtering. There are four hidden small tubes, two 6J and two 6BX7 as driver tubes right behind two B+ filter chokes.  
 
Caps and driver circuit transformers are located insider the six transformer cases on each side of the amp.  
 
Full spec, test results and more detail pictures of the amp will be coming real soon.  
 
Please be gentle and not to laugh too loud about my humble creation when you next see me. Of course, comments and recommendations are more than welcome la.  
 
bobui
16-06-18
09:40:42
回覆 (350): Sense of Humor is a sparkle of your intelligence
One of my all time best song writer. You like?  
 
bobui
16-05-11
14:04:54
回覆 (349): Your surname (last name) and mine?
Windsor not a castle!  
 
The truth is as I have discovered from various webs is that The Royals family had no surname before 1917!  
 
Windsor was somehow declared to be the royal house surname from 1917 but is not being used in a common way. No one ever call Prince Charles Windsor or Queen Elizabeth Windsor.  
 
bobui
16-05-01
12:07:05
回覆 (348): Your surname (last name) and mine?
Windsor I think.
drwkng
16-04-30
17:15:01
回覆 (348): Your surname (last name) and mine?
Windsor I think.
drwkng
16-04-30
17:15:00
回覆 (347): Your surname (last name) and mine?
While I was listening Beethoven Sonatas at home. A question suddenly came from within me.  
 
As we all know this April is our ex-god mom Queen Elizabeth II 90th birthday month. I am just wondering..........if I want to send her a birthday card. What is Queen Elizabeth II surname? Her full name is Elizabeth Alexandra Mary which was found in the web. But surely Mary cant be her surname.  
 
Too bad, I don't have a god mom now. You have?  
 
bobui
16-04-30
10:46:08
回覆 (346): Young looking M.A
Six LPs for less than HK$700.- The Ravel and Chopin by M. Argerich is.......I adore very much.  
 
And very good choice of photo on the box set cover. One of the very few young looking M. Argerich. Special!  
 
bobui
16-04-25
14:05:58
回覆 (345): OMG!
 
 
bobui
16-04-22
13:25:24
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