Seems like two 5AR4's for a preamp is overkill, since one tube can provide enough current to power a Dynaco ST-70 power amp. However, it you like the glow, the more the merrier. Just don't put the preamp in a case where you can't see them.
A quick DuckDuckGo turned up this: The Website.
"EVO 400 Preamplifier - $4499" -- Built for those who have more money than sense. Typical audio grifters.
Magic Resistors! You'll pay $HUNDREDS for a part you can get from Mouser or DigiKey for pennies. Any metal film resistor will be linear and low noise. Of course, they won't be pink, so I guess there's that to consider. 😀
Pure. Tube.
Save that Swiss made, silver plated OFC wire for your VHF projects where it will make a difference. What makes a difference at 200MHz makes no difference at 200Hz.
The 12AU7 is an RF type, not an audio type. As an audio VT, they just plain suck. As you'd expect if you look for circuits that feature the 12AU7 -- loads of oscillator/buffers, frequency multipliers, PP Class C drivers, product detectors/mixers, and quasidigital devices like astable multivibrators, one-shots, Schmidt triggers, R-S latches. In other words, nonlinear. They'd do better with 6SN7s or 6FQ7s (the 9-pin mini version of the 6SN7).DiaLogue FRONT-END CIRCUITRY
The DiaLogue Premium uses three 12AU7
They're ripping you off.
Sure, the product is overkill and marketed toward the purchaser with money to throw around. I would think that a forum with geniuses like you guys would possibly investigate the performance of this product to see if it was superior to products in the same price range. Instead we throw comments like 3 rectifiers would even sound better. I really thought some of you were better than this.
Certainly not "new technology " this was used way back in the ,30,s not to give "improved sound " but to beef up the current available at the time.
I have various old radio/wireless books from that era including WW from 1912-1948 in bound volumes .
Much is made of modern innovation but patents in those days show a very high degree of innovation and you would be surprised at some of the circuits.
Valve/tube radios had push button control- electric motor wavechange and ranging - bfo-noise reduction -push-pull monoblock amplifiers or class A PX4 output-"magic eye " tuning etc etc.
John Logie Baird -color TV with stereophonic sound (electronic not mechanical ).
Radios went downhill for the public after WW2.
I too am not taken in by this type of advertising.
I have various old radio/wireless books from that era including WW from 1912-1948 in bound volumes .
Much is made of modern innovation but patents in those days show a very high degree of innovation and you would be surprised at some of the circuits.
Valve/tube radios had push button control- electric motor wavechange and ranging - bfo-noise reduction -push-pull monoblock amplifiers or class A PX4 output-"magic eye " tuning etc etc.
John Logie Baird -color TV with stereophonic sound (electronic not mechanical ).
Radios went downhill for the public after WW2.
I too am not taken in by this type of advertising.
This, right here, may explain the difference. That plug-in module will certainly raise the DC voltage, as the forward drop of a Si diode is way less than that of a hollow state diode. That was the reason why I went hollow state for a project: a junk box Stancor PTX that had the right current rating, but produced 100V above the design nominal voltage with Si diodes, but was spot on with a 5U4GB (100Vforward @ Isurge= 800mA) Also, removing the hollow state diode unloads the PTX (no heater current) further increasing VPP. You may be flirting with poofage by doing this, stressing filter capacitors with over voltage.
The difference is that capacitors do make a difference, and it's something you can measure: the E/D hysteresis of the dielectric, that does affect linearity and harmonic generation. The worst dielectric materials are the highly polar ones that also allow you to pack many uF's in small packages. Metal oxides, ceramics, and some highly polar organic materials like polystyrene, polyesters and polyamides (both contain loads of highly polar COOH groups). The better ones are polypropylene and teflon (polymers of straight chain hydrocarbons with low polarity, but which also don't have the permitivity of polar dielectrics.)
Tube rolling also has a basis in fact: VTs are low gain devices, and the circuit performance is more dependent on the active device. BJTs are high gain devices, and so circuit performance is independent of the actual device. So long as the BJT in question can process the signal frequencies, it makes no difference what actual device you use, unless you need some special property like an unusually low noise figure, ot something like that. Tube rolling will make a big difference if you're not including NFB, as NFB serves to make the performance less dependent on the active devices present.
"Maybe the air-gap between a tube's anode & cathode prevents some junk that can otherwise tunnel through a "Sand-State" device". If you have an air gap between the cathode and anode, "junk" getting through are the least of your problems. 😀
Myles, styrene is vinyl benzene, which is non-polar hydrocarbon. Amides and esters are derived from the carboxyl group (COOH). The OH is replaced with either oxygen (ester) or NH (amide) and something else tied to the available bond. Esters and amides definitely are polar.
A dielectric "transparancy" pecking order sometimes seen is PTFE, polysytrene, polypropylene, and then the rest. That top 3 are, as you indicated, non-polar. We don't see nylon dielectric caps. and nylon is a polyamide.
A dielectric "transparancy" pecking order sometimes seen is PTFE, polysytrene, polypropylene, and then the rest. That top 3 are, as you indicated, non-polar. We don't see nylon dielectric caps. and nylon is a polyamide.
I remember JLH commenting on polypropylene capacitors and saying --be careful which ones you buy, he found out many were made with packing grade material.
I do use polystyrene and polypropylene capacitors, the high quality versions are pretty dear though.
I saved many high quality polystyrene capacitors by removing them from old tube Tektronix oscilloscopes along with --6080 tubes , some had heater/cathode shorts but I used a CRT rejuvenator to remove the shorts.
I do use polystyrene and polypropylene capacitors, the high quality versions are pretty dear though.
I saved many high quality polystyrene capacitors by removing them from old tube Tektronix oscilloscopes along with --6080 tubes , some had heater/cathode shorts but I used a CRT rejuvenator to remove the shorts.
Thank you for the many replies; I'm getting my audio head expanded. I appreciate the variety of opinions and factual information, which keeps me learning.
Although I still think some of the EVO's "attributes" are over-kill, and that PrimaLuna may have been able to achieve a similar level of audio quality at less expense, that preamp does seem to be competitively priced for the high-end market.
Coming at this from a 1960's starting point, audio is now in a galaxy I never had a clue would exist.
Although I still think some of the EVO's "attributes" are over-kill, and that PrimaLuna may have been able to achieve a similar level of audio quality at less expense, that preamp does seem to be competitively priced for the high-end market.
Coming at this from a 1960's starting point, audio is now in a galaxy I never had a clue would exist.
There´s a WIDE range between disagreeing and being slammed.
In general, results tend to depend on quality of opinion being held.
Wild, extreme opinions will get the most opposition ... no surprises there.
And those stirring the waters shouldn´t be suprised at the amount of mud they rise.
You are wrong there.
By posting on a PUBLIC Forum, you are ASKING FOR comments.🙄
You don´t like them?
Then YOU keep your opinions to yourself.
The Ultimate preamp.......10 rectifier tubes.
2 banks of five 1B3GT's series strung across 6.3 volt windings with high voltage from coiled wire jumping from top cap to top cap.
I think a lot of people have a few 1B3's stuck in a box somewhere. What a steampunk look!
2 banks of five 1B3GT's series strung across 6.3 volt windings with high voltage from coiled wire jumping from top cap to top cap.
I think a lot of people have a few 1B3's stuck in a box somewhere. What a steampunk look!
Yeah Mike; like mini Tesla coils as seen in sci-fi movies of the 30's. I'll have to admit enjoying the blue glow pulsating to the bass when only candlelight casts softly upon the finals. An actual arc, dancing in sync to the music, would be super cool.
With so much talk about 1B3 half-wave rectifiers I had to look them up in an old version of WW valve ( tube ) equivalents ----honestly I was astounded that a very high voltage tube used in a very early TV EHT circuit would be used in an audio pre-amp.
2ma output ,later EHT line rectifiers were wired into the LOPT and many a shock I have had repairing tube TV,s.
I have a large collection of tubes/valves and an AVO MK4 VCM but not that early US tube ,I am very open minded but my engineering brain has trouble ingesting this.
2ma output ,later EHT line rectifiers were wired into the LOPT and many a shock I have had repairing tube TV,s.
I have a large collection of tubes/valves and an AVO MK4 VCM but not that early US tube ,I am very open minded but my engineering brain has trouble ingesting this.
This thread jack was intended as humor. But a bragging rights with a preamp with rectifiers that can stand 25,000 volts!
That's AOK #567, this OP enjoys going OT on the scenic route with humor (especially) or to previously unthunk dimentions. Those 1B3s were some very stout tubes and I remember being impressed with the power and voltage those smallish envelopes handled.
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