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Ecl82 amplifier connection

November 25, , AM Welcome, Guest. Please login or register. I Really fancy a Tube Amp. I'm sure somebody on this forum has used China Hi Fi so any thoghts on the amp and the retailer would be much appreciated. Re: I Really fancy a Tube Amp. IMO chi-fi valve gear is not really advisable for first time users.


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WATCH RELATED VIDEO: tube amplifier part 1 ( ECL82 / PCL82 )

Building a Valve Amplifier Part 1: Design, Components and Layout


By continuing to use the forum you conform your acceptance of these. If you are not happy to accept these you must stop using the forum and delete our cookies from your browser. User Name Remember Me? Mullard ECL82 stereo - where has the voltage gone?

I've just finished rebuilding my Mullard 7W stereo amplifier, following the Mullard circuit and layout closely. There are two deviations arising from the fact that the transformers are from a Dynatron stereo radiogram which was working before I removed them. The deviations are: 1 the output transformers do not have screen grid taps, so I have connected those points on the tagboard to the HT, via separate 1k5 resistors.

Apart from the variations mentioned above, I have followed the Mullard circuit and layout faithfully and have checked and re-checked all the wiring. There is a loud 50Hz hum and two other error conditions at least! These are: 1. This is reflected in low voltages in the rest of the circuit. There is 22VAC on the ground circuit which is not tied to the chassis ground connection. I would be grateful for pointers to where I am losing the HT, as it was there in when I assembled this previously on an unsuitable chassis.

I'd also value advice on whether there should be 22VAC on the ground circuit. I attach a couple of pics. I am aware that primary leads to the OPTs and some of the other HT connections are too long at present.

EDIT: I have just grounded the circuit ground to the chassis ground and both the voltage errors are corrected! No AC on the ground circuit and the HT is more or less correct. BUT the loud hum still remains Though this a less interesting problem, I'd be grateful for advice on how to correct this, as it may be related to my use of different transformers. Attached Thumbnails. Last edited by qualityten; 15th Jun at pm. Reason: Voltage problem corrected after posting. Re: Mullard ECL82 stereo - where has the voltage gone?

Do both channels behave the same way? What do you mean by chassis ground and circuit ground and why did connecting them together fix your HT fault? Is it simply that you were measuring from chassis and that was not connected to 0V? The transformers would only cause hum problems if they are being saturated and if they were designed for ECL82's they should be OK. Not having the UL connections will increase the open loop gain and that might cause instability. Do your DC voltage measurements match those in the Mullard document?

Most important is the ECL82 pentode cathode voltages. Lookin' good David. I like your chassis idea - only 2 bends to do! I would doubt the hum is anything to do with the transformers, unless they're magnetically coupling to the mains TXF, but then it shouldn't be a 'LOUD' hum.

I haven't got the circuit to hand but it looks as if your main smoothing can is in contact with the chassis? I seem to recall it should be isolated and tied to the main grounding point. Where are the ECL82 g2's fed from as there may be ripple on the supply? If you AC ground the input valves anode is the hum still present? Same with the its g1? If it's the same on both channels then grounding or PSU seem likely.

Andy PS Just seen that it's 50 Hz! Find More Posts by yestertech. Thanks for these pointers. I'll respond to them after work tomorrow. Thanks for the diagnostic questions and observations given yesterday. PJL, I can confirm that both channels do behave the same way. I'd be glad to learn the correct terminology. I was measuring the latter when it was not connected to 0V! My DC voltage measurements broadly match those in the Mullard document.

The triode voltages of the ECL82 are more or less as per the Mullard document. For the ECC83, the anode voltages are about 20V higher and the cathode voltage somewhat lower, 0. Yestertech, my smoothing can is in contact with the chassis, but it is not in contact with the three capacitor grounds. I restuffed the can with three new 47uF capacitors. I've done this before with other projects, but I may have mixed up the grounds for C15 and C12 and C, i. Grounding G1 of the input valve has no effect.

I don't know how to AC ground the input valves anodes. Reading the section on diagnosing and eliminating hum in Morgan Jones' Building Valve Amplifiers, I think the AC hum is coming from near the reservoir capacitor. Unfortunately, I don't have high voltage oscilloscope probe to verify this. Thanks again for help with this. Apart from the hum, it sounds great! Am I right in thinking that this is likely to be a PSU issue?

Last edited by qualityten; 16th Jun at pm. Is it 50Hz hum or Hz? What happens if you short the input? What happens if you run it without the ECC83? I am not sure what you have done reg the heater supply , try a wire wound pot across the 6'3 v and the centre to earth , adjust for min hum. I think with your hum problem I would focus on your earthing arrangements.

These Mullard circuits do work pretty unfailingly if you follow all the instructions exactly, and they do give details of how the earthing arrangements should be physically wired. Worth rechecking the exact connection points and routing of all the earth connections - including where they are connected to chassis. A quick reply: It's a 50Hz hum which stops abruptly on switch off. I have ohm resistors, with the junction to earth across the heater supply.

Is that value too high? I have not tried decoupling the G2 with caps. Mick, do you mean 22uF or 0. And thanks for the advice to recheck earthing arrangements. I have built s and s successfully without hum, but those have been mono. Thanks for all the interest and advice. A failure of one or the rectifier diodes in the EZ81 would create a 50Hz hum.

So would a bad connector in the valve holder. A DC HT with a large amount of ripple could confuse some multimeters. The negative of C15 should go to the 0V HT winding connection by the shortest and most direct route to avoid current pulses being superimposed on the signal ground. Silicon, thank you for these further areas to check. I did test the EZ81 with another. But the valve socket I used for it is an NOS one that has been in storage for decades, while the others are new, so I need to check connections there.

I intend using a dual can capacitor for C12 and C, and using a separate cap for C15 with a separate ground connection. Thank you for this help, and valuable bite-sized tuition. Have you correctly identified all the h. Switch off your amplifier, wait for the valves to cool and the h. You should get about — ohm between pins 1 and 7 of the EZ80 and about — ohms between pin 1 and pin 7 of the EZ80 and chassis. If your reading is much higher or infinite, you have not correctly identified the centre—tap of the h.

Once you have identified and corrected, if necessary, the h. These two checks verify the correct connection of each ECL82 tetrode section to chassis to give it it's correct grid bias. Next, use your ohmmeter between pin 3 of the EZ80 and each ECL82 pin 6 to verify the output transformer primary is correctly wired to the h.

Please confirm all the above is all correct so we know there's nothing radically amiss with your h. Chris Williams. This thing's not fixed because it doesn't want to be fixed! Try running the heaters off 6V dc supply if you suspect this as source of hum.

Thank you for the further pointers. I appreciate the time and interest it represents. Apologies for the length of what follows.


Common Tube Amp Malfunctions: My amp makes no sound.

You have JavaScript disabled or are viewing the site on a device that does no support JavaScript. Some features may not work properly. The circuit is basically a multivibrator constructed around a double triode I used ECC83 , and oscillates around 1KHz. From all the existing tubes, for sure the most interesting ones are the indicator tubes. The magic eye tubes are just small CRT derivations, usually they also have a triode built-in, as an amplifier.

Why the STC Amplifier? The author came across articles on the Super-Triode-Connection (STC) audio power amplifier in issues of MJ.

RESTORATION OF A MARSHALL "MODEL 1930"


Users browsing this forum: Google [Bot] and 3 guests. I thought that I could build some small 3 watt amps for the kids to play with, the only thing I need are some power transformers and a few odds and ends. I've been looking on the net for some schematics and I found this one, the OPT's are 5k so I'm OK there, but I am a little unclear about the power transformer. Thanks Guys. You do not have the required permissions to view the files attached to this post. The xCL82 requires about volts on the secondary winding. Also this tube have more power in pentode mode, but have great sound in triode mode. I used a PCL82 tube with 16V ohm 0. The amplifier is powered by a grid-shaped transformer with a glow voltage selected according to the tubes for me 16V 0.

Amplifier Boards Wiring - Caledonian Audio 6BM8/ECL82 SE Assembly Manual

ecl82 amplifier connection

I figured it was about time I built another valve amplifier, and since I already had most of the required parts in stock, here it is! There are a pair of extra holes drilled here for a couple of EM80 magic-eye valves wired as VU meters to give a bit of a lightshow. Power will be supplied from low-voltage DC, running through a high voltage DC-DC converter for the anode supply of v, and a 5A buck converter for the 6. I have removed the second 1N diode down to ground, leaving only a single diode. Most of the parts comprising the ECL82 amplifier stages are mounted directly on the back of the valve sockets, requiring only a 6.

The amplifier to be described here was designed and built as a practical application of stereo simplex principles.

Sony Tube Amp 6BM8 5MK8 ECL82 Vintage Integrated Amplifier Japan


Once a discarded relic, over the years the humble vacuum tube has been rehabilitated in the arena of specialist audio. There are plenty of tube amplifiers now being manufactured, with a popular choice being headphone amplifiers that use a tube as a gain stage followed by an op-amp as a buffer with a low impedance output. The tube circuit is a very conventional anode follower using an EF95 pentode. An NE steps in for the op-amp buffer role, making for a very simple circuit. Power comes from a set of four Lithium-Ion cells with associated charger and balance boards, while a little switching boost converter provides the volt HT for the tubes. Our friend [Pete] was reminiscing over the golden days with his old and broken antique Grundig Majestic console when he realized it deserved proper refurbishing.

Need some help with a single tube amp.

Watford Valves is a U. Check out the following reviews in the guitar and audio press. Watford valves through its unique valve test equipment offer the most comprehensive and thorough valve test facilities on valves available today. Watford valves are the only company to offer full drive tested signal valves and burst tested output valves under the Harma valve range. Watford Valves "runs them through more checks than any other facility in the world" Dave Hunter, Guitar Magazine, Nov

It has a pentode plate dissipation rating of 7 Watts with convection cooling. A single 6BM8 may be used as an economical low power mono block amplifier or a.

DIY Audio Projects Forum

They contain preamplifier triode and power pentode in one tube. I used PCL82 tubes with 16V 0. The amplifier is powered from the mains transformer.

Mullard stereo ELC82 amp build issues (OPTs and oscillation)

RELATED VIDEO: ECL82 Valve/Tube Amp revisit and inside and circuit (4K)

By continuing to use the forum you conform your acceptance of these. If you are not happy to accept these you must stop using the forum and delete our cookies from your browser. User Name Remember Me? Mullard ECL82 stereo - where has the voltage gone? I've just finished rebuilding my Mullard 7W stereo amplifier, following the Mullard circuit and layout closely. There are two deviations arising from the fact that the transformers are from a Dynatron stereo radiogram which was working before I removed them.

Post by devastator » 16 Dec , Post by kleuck » 16 Dec ,

Sound Practices Magazine Online! T ube regulators were invented in the s to replace the bulky battery power supplies used with scientific instruments. There were many types, some simple, some complex. The regulator presented in this article is of the simple variety: one tube. The benefits of a single tube regulator are simplicity, compactness, low cost, and minimal heater supply requirements. The disadvantages are limited output current about 35 mA for the unit described here and only moderately low output impedance compared to more complex types. Well, there are good reasons for and against.

Read in Dutch. Introduction about modifications: The ULS2 is already some years on the market and meanwhile I have received several requests for modification of the original circuit. I tested these and in most cases I was not convinced that they offered a real improvement. I got questions about upgrading with other brands of capacitors or resistors or connectors.




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