Here is amp for bass guitar with 6x6BG6Ga in output. Nothing special, but works very good with perfect tone.
Ia-0=6x28-30mA, Ia-max=6x100-110mA
Uout is more than 32Veff. (at 4 ohms resistor, and 41Hz) with distortion less than 5%.
I'll like to hear experience how maximum voltage can stand 6BG6GA (only "Sylvania" and "Philips ECG", not other types !!).
Ia-0=6x28-30mA, Ia-max=6x100-110mA
Uout is more than 32Veff. (at 4 ohms resistor, and 41Hz) with distortion less than 5%.
I'll like to hear experience how maximum voltage can stand 6BG6GA (only "Sylvania" and "Philips ECG", not other types !!).
Attachments
200W with 6BG6GA
Very interesting and beautiful realization this schematic is an ultimate power in AB2.I have a question, do you think should go instead 6BG6GA tubes, tubes 807 or the Russian G807???
-If you can and can not publish some secret features and course data output transformer (OT)?
-something about the development and what problems you encountered in its realization?
Thanks!
Very interesting and beautiful realization this schematic is an ultimate power in AB2.I have a question, do you think should go instead 6BG6GA tubes, tubes 807 or the Russian G807???
-If you can and can not publish some secret features and course data output transformer (OT)?
-something about the development and what problems you encountered in its realization?
Thanks!
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I sense dedication here. How long have you been at this project? Also is that a re-cycled chassis? Always good to re-use.
Maybe tube 807 (Pa=25W) work fine with Ug2 300-350V, but 6BG6GA wit big anode ("super tube") have Pa~30-35W and work good with Ug2~450V (and 500V!).
Output transformer have cca 30cm2 (5x6,3cm) and 1790/0,50mmCuLack turns(555+340+340+555) at primary, and 4x40 turns at secondary(first 2 windings with 1,60mmCuLack, and second 2 windings with 1,30mmCuLack). Schematic of wire connections can see at schematic).
Chassis is from old 19"-rack (frame), with new top sheet-metal.
I spend 1 week to build amp, plus 3 days for winding transformers and chokes.
Front and back plate make with "Zveckform-card-maker"-program, print at ink-jet printer, cut and than stick with transparent lack-spray.
Generally I have no problem with building amp, because I measure and match tubes before ("Neuberger RPM370" tube metering table), and use new components.
Output transformer have cca 30cm2 (5x6,3cm) and 1790/0,50mmCuLack turns(555+340+340+555) at primary, and 4x40 turns at secondary(first 2 windings with 1,60mmCuLack, and second 2 windings with 1,30mmCuLack). Schematic of wire connections can see at schematic).
Chassis is from old 19"-rack (frame), with new top sheet-metal.
I spend 1 week to build amp, plus 3 days for winding transformers and chokes.
Front and back plate make with "Zveckform-card-maker"-program, print at ink-jet printer, cut and than stick with transparent lack-spray.
Generally I have no problem with building amp, because I measure and match tubes before ("Neuberger RPM370" tube metering table), and use new components.
Thanks very much for information.I thincs that using the proposed power tubes can be more than 200W (!!!!), but with 6X807 valve can easily get 170W-200W, but the condition Ug2 = 300V (max) and not exceeding Ua = 720V, even Raa = 2K and bias adjusted corect.Thanks again for information and congratulations for their achievement.
Yes, maximum continues power is more than 250W (distortion~10%), but peak power is bigger. Before 25-30 year I build amp with 2x807 tubes with Ua=780V, Ug2=320V, Ug1~-38V, Iamax=2x110mA and Raa=10Kohms. Output power was more than 100W, but drive was with transformer (1:0,5+0,5) and EL84 triode connecting. Amplifier has good sound, but 807 tubes works hard with Pamax>25W and not more than 1 year. More power can give You GU50 (LS50)(also cheep), and expensive EL34, 6CA7, KT77, KT88, 6550, etc., but all of that tubes has anode connect at base and big problem with arc in sockets.
You absolutely right, I have worked 807 years ago, four or six tubes in PP, the results were excellent, but I used 807 Mazda BELVU (G807 are different from Russian). What about the DINACORD EMINENT 2 working with EL34 PP with Ua = 800V and 400V voltage on Ug2 = .?!?!... and a power output of 100W !?!?!
You're right, the most important issue is that it can pierce stranded in such tensions, especially when pregnancy is adapted or not existing (risk !!!). If anode tubes up the glass problem is much better, but risk is higher for OT .....
How soon will try and I proposed schematic for you but with 807 other tubes I have.
Thanks for the reply!
You're right, the most important issue is that it can pierce stranded in such tensions, especially when pregnancy is adapted or not existing (risk !!!). If anode tubes up the glass problem is much better, but risk is higher for OT .....
How soon will try and I proposed schematic for you but with 807 other tubes I have.
Thanks for the reply!
Know that chasis(Iskra)and main power transformer(Iskra).over 45 old and stel working,thats quality.Made some 2x50w hi-fi tube amp before 10 years on the same chasis and same main transformer(colected from junk yard).Vozdra Davorin, Salut Lazaroiu
Close: Chassis is from "Iskra"-rack for public address 200W-amplifier(100V uotput), but iron of main and output transformers was from "Main voltage regulator", decompose and rewind for this project.
Transformers from "Iskra-cinema" amplifiers are much smaller (I have some of them).
Transformers from "Iskra-cinema" amplifiers are much smaller (I have some of them).
I have original transformer from "Iskra"200W amplifier: Main transformer is 25cmcm total (5x5cm) and windings are 2x340V/0,6A, 40V/0,04A and 6,3V/10A, and output transformer is 18cmcm total (4x4,5cm) with 3,8Kohm for primary, 100V/70V/50V for line speaker outputs, and 3xwindings for separate negative feedback. Amplifier was working with 880V at anode, 440V at G2 on 6xEL34 and 2xECC81(12AT7) for phase splitter and driver.
Normal 6BG6 is octal version of 807, but "Philips-ECG" and "Sylvania" models are more like 7581A with anode cap. They are designed (all version) for B&W-TV horizontal output, and works equally or better in any (and HF!) amplifier designed for 807.
Normal 6BG6 is octal version of 807, but "Philips-ECG" and "Sylvania" models are more like 7581A with anode cap. They are designed (all version) for B&W-TV horizontal output, and works equally or better in any (and HF!) amplifier designed for 807.
Interesantno Davorine I hawe exactly same main transformer with same primary/secondary voltages/curent from 50 years old ISKRA PA amps.That transormer suply two separate hi fi 50w amps on the(same) one Iskra chasis(450v anode and 4xel34 & 4x ecc83).That what I say is next :This oldschool transformer engineer and manufacturer KNOW THE JOB.BTW in series production this transformer have electrostatic shield beetwen primary and secondary windings(there is one contact piont on the botom of secondary contacts line,so separate shielding i not neceserity(like you did).Anyway YOU did good job.Best Regards from South Banat
Maybe separate shielding is not necessity when amp is build in metal rack, but this amp will be build in wood box. Also is problem with interaction of between main transformer, bass guitar pic-ups, and triac/tiristor regulators of stage light reflectors.
Old transformer from "Iskra" amplifier are good, and i use main transformer in future, but output transformer must be rewound because they have not any low impedance secondary winding.
Old transformer from "Iskra" amplifier are good, and i use main transformer in future, but output transformer must be rewound because they have not any low impedance secondary winding.
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