Photo- the 0.5mm thick brass plate escutcheon of my Vampire 500W..a well designed amp deserves a good reflection...Being half s german, I like metallic views...makes all the difference with no screws visible on the front..compared with ally panel behind with flush set screws.
Lettering is last generation rub-on letraset alphas' and the next step is an engraver to do the job proper. It isn't as expensive as one makes out to be and I can recommend it. Amp dimens 18"x18" or ~46x46 cms.
Despite Wavebournes thread....the dilemma of where to mount vs. length/breadth etc, I prefer an uncluttered front panel....Judge for oneselves . Brass plate can be picked up in good hardware stores.-make sure it hasn't got scratches in it, though sleeks can be rubbed out with wire wool and brass polisher.
richy
Lettering is last generation rub-on letraset alphas' and the next step is an engraver to do the job proper. It isn't as expensive as one makes out to be and I can recommend it. Amp dimens 18"x18" or ~46x46 cms.
Despite Wavebournes thread....the dilemma of where to mount vs. length/breadth etc, I prefer an uncluttered front panel....Judge for oneselves . Brass plate can be picked up in good hardware stores.-make sure it hasn't got scratches in it, though sleeks can be rubbed out with wire wool and brass polisher.
richy
Attachments
I have no idea where I got it from. Sometimes I like taking parts from dead machinery for no apparent reason. I just find some parts interesting. Maybe some day I will do some 'art' with electronic parts, although I doubt it. In the meantime trash keeps cluttering my basement.
Good job, richwalters.
This amp isn't to be "messed" with..and requires premium grade components.
Raw meat overview:
8x EH KT90; 4x 12BY7A;2x E80CF; 1xECC83
double parallel push-pull.
Williamson config amp with active CCS diff driver (12BY7A)
E80CF as concertina/triode config 1st stage.
Selectable pfc power supply 1.5kW rated, operates at 75Khz;
Amp can be use in bridge mode for MI enabling 500W+ mono.
Raw data;
4 selectable B+ operating conditions:-
B+ 210V low power low quies 15mA per o/p tube;
B+ 300V ...50+50W 100mA quies per o/p tube close class A Hifi,
B+ 410 MI standy condit- near tube cut off.
B+ 600V mono bridged full 525W continuous sinewave, just over 250W per channel AB1, 75mA quies per o/p tube, full output close to 0.2A per tube.
The driver stage operates at a perm 360V at 60mA both channels. This is current dumping.
Logic circuit enables Hot switching i.e Neg Bias volts switches with whatever B+ setting.
Measured 1dB below full power, resp-1dB@ 17Hz-50Khz (-3dB 100Khz)...... with input transformer -3dB 50Khz
18dB/oct HP input filter (butterworth) -3dB 15Hz (good for octave shifter deep keyboard work)
Distortion, nom 0.2% 1Khz per channel at full AB1 output; class A condition at 45+45W ~0.05%.
Unconditionally stable; nom global feedback 19.5dB can accept another 14 dB before instability sets in...Stable for electrostatics.
Square wave asymettry near optimal, 3rd harmonic Fourier criteria easily acheived. Loop damping and circuit Q optimised.
Damping factor 20, ~4 ohms
hum & noise ~-75dB below full o/p per channel.
Crosstalk 15Khz ref 150W per ch = -80dB, (other input s/c) requirement for studio console work. This is a tough one to acheive.
Power supply HF harmonics barely undetectable on spectrum -100dB down. 100Hz ripple ~-80dB down.
Input sensitivity +6dBu (for full o/p) balanced 10K imp XLR per channel
Other features; Yes it has 2W carbon resistors as grid stoppers.
Watchdog for bias fault and B+ asymmetry, input mute# 20 sec warm up, AC brown out, reset per missing cycle, (quite common on land lines).
Layout designated for long life; electrolytics and ventilation in properly assessed locations;
Mechanical, weight ~55kg#120Lbs; 4mm ally plate and bracing used around transformers.
Build time ~6months in evenings.
There is a considerable amount of test data and doc which I'm currently softwaring.
Output transformers; standard M6 laminate, customed spec'd with paper isolation and grade 2 wire, 18 sectioned designs; designed frequency response 15Hz-50Khz; 4 sep output winding configurations. Majestic Transformers, Poole, Dorset UK. In amplifers such as this one, the hand wound transformers were quite well matched by the same person on the winder resulting in identical R/C phase correction components on each channel.
In the past, as the yellow polyester tape replaced kellogs paper, over time the leakage capacitive actually started to rise as the self algamating properties were taking place. This is the reason that Quality output transformers for tube amps should only be quickly end dipped to seal against moisture and NOTvarnish vacuum impregnated as per mains types.
The unexpected ? Amplifiers of this class come in for some disection.The extra wide frequency response was the big surprise.The 12BY7A diff driver has a superb performance in dealing with output stage Miller, but with the unexpected high freqency bandwidth, this did show some interaction between various makes of input tubes
ECF80,7643,6BL8 but best results were with E80CF. This tube wasn't designed for audio, and quite alot are microphonic. In practice, the proximity of the unscreened input tube should have been place slightly further away from the capacitive voltage swing of the output tube anodes.
In circuits with such a wild bandwidth as this one, the grid stoppers do a vital job in curtailing a wild response (designed on a stage to stage basis) and will effect the square wave shape, as did the output stage A-g2 zobels. These values wern't arbitarily chosen, as je higher the frequency, the zobels and grid stopper values do effect the slewing.
The B+ of 600V is an annoying voltage...requiring stacked up electrolytics and 600V rated semis are ruled out favouring 1kV types. Fortunately there are quite alot of 1kv devices in the TO220 package around...space is a premium.
The associated dangers of building power amps which use high Joules is an issue for some and any recklessness with shortcircuits which result in component destruction require eye & hearing protection.
Like the previous 5, I enjoyed every minute of puting this one together.
This is the last of.... Hurrah Williamson !
richy
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The colum is PS of amplifier. It has 3 separate voltage with the kens for 3 stage of amplification and it has no electrolytic capacitors
My GOSH !
This thing is extreme - huge cabinets full of high voltage capacitors - looks like a doomsday device
Pete Millett DCPP or "Engineer's Amplifier"
6CB6/6NJ6 Push-Pull Pentode with distortion cancellation.
More info can be found here - DCPP Amp
99% done, just need to finish a bit on the chassis wood.
It sounds fantastic!
Hi, Classic style serious with a touch of blue aspect that match with any other device, definitively my style. Let me make a question, the output valves are 6NJ6 or 6JN6 ? Can you show the electronic diagram of it?
Best Best
This is a Christmas gift I am DIY to my wife.
6AQ5 pp 12AU7 ,EF86
Does she can enjoy this kind of gift? Incredible Wife, please give the formula to the rest, how get one with this taste?
Best Regards and congratulations at the end of era.
a singled-ended 1625 amplifier - pentode front end, gas tube regulated screens.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hi Tim, that mean How you doing in Korean language, actually is the noise of the word that I listen from a friend.
Sorry I guess you are descendant from This land.
The best for you.
Does she can enjoy this kind of gift? Incredible Wife, please give the formula to the rest, how get one with this taste?
Best Regards and congratulations at the end of era.
I can imagine the gaiety and mirth that filled
She's audio vintage fan .
PCB's gift of VNAV ,
and My project of the year
Attachments
Hi Tim, that mean How you doing in Korean language, actually is the noise of the word that I listen from a friend.
Sorry I guess you are descendant from This land.
The best for you.
Ah, I see.
I learn a new word, I grew up I'n the state but I am born I'n sai Gon Viet nam
These Yamaha are great speakers, I didn't really care for them as first but they grew on me
Deviating a bit from my original intent, of keeping things in chronological order- here's a set of amps and preamp which I built, that I just sold this morning.
The amps started as a very rusted set of Dynaco MK III chassis, that I got in pieces. In fact, here's how bad they were to start with:
Since I didn't get any transformers, I decided to experiment a bit. I have always been a big fan of 6L6 type tubes- so, I converted the design over to 6L6GCs. The output transformers are 6.6K 60 watt UL interleaved-winding Hammond units, and the power transformers were from a pair of Thomas organ amps. The feedback loop and bias circuits were re-worked to work correctly with the new tubes and transformers, and the power supply was converted to solid-state rectification, with much more capacitance than stock. Output is about 40w/ch, with 4 and 8 ohm outputs.
The preamp was built from scratch, to be a close cosmetic match to the amp chassis. The phono stage is a modified Dynaco PAS type (using a bit of each of the Latino and Curcio mods, melded), and the line stage is a single-gain-stage buffered circuit, that I have worked up myself. It's completely point-to-point wired inside (no circuit boards), with a solid-state rectified power supply with DC heaters.
It was a little sad to see these go, as they sounded SO GOOD (especially the mids- and they were SO dynamic). But, now I have resources to buy parts to build more amps!
Regards,
Gordon.
The amps started as a very rusted set of Dynaco MK III chassis, that I got in pieces. In fact, here's how bad they were to start with:
Since I didn't get any transformers, I decided to experiment a bit. I have always been a big fan of 6L6 type tubes- so, I converted the design over to 6L6GCs. The output transformers are 6.6K 60 watt UL interleaved-winding Hammond units, and the power transformers were from a pair of Thomas organ amps. The feedback loop and bias circuits were re-worked to work correctly with the new tubes and transformers, and the power supply was converted to solid-state rectification, with much more capacitance than stock. Output is about 40w/ch, with 4 and 8 ohm outputs.
The preamp was built from scratch, to be a close cosmetic match to the amp chassis. The phono stage is a modified Dynaco PAS type (using a bit of each of the Latino and Curcio mods, melded), and the line stage is a single-gain-stage buffered circuit, that I have worked up myself. It's completely point-to-point wired inside (no circuit boards), with a solid-state rectified power supply with DC heaters.
It was a little sad to see these go, as they sounded SO GOOD (especially the mids- and they were SO dynamic). But, now I have resources to buy parts to build more amps!
Regards,
Gordon.
