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El84 transformer impedance

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WATCH RELATED VIDEO: Vacuum Tube Output Transformer Measurements Determining Turns \u0026 Impedance Ratio \u0026 Matching To Tubes

output transformer primary impedance questions


Users browsing this forum: Google [Bot] and 54 guests. Ads are not permitted. I have a Guild New Englander that needs a bass output transformer replacement. From my research I know it is a push and pull with a 16 and 8omhs output put have no clue on the plate load needed.

I have inquired with a guy who builds transformers but he has asked me to ask you guys because he has never seen this type of amp that uses 3 output transformers, one for the right speaker, one for the left and one for the bass speaker. I have added the schematics and hope someone has any advise. Thanks in advance Martin. You do not have the required permissions to view the files attached to this post. Re: Guild New Englander Bass Output Transformer Replacement by lorenzw » Oct Fri 30, pm I restored one of these "faux rolltop desk" stereos earlier this year and now display it in my living room.

It works great, even with the unusual "center channel bass" design. I later found a Heath FM multiplex decoder online and installed it; that too works quite well. I took note of the odd amplifier output amp design when I recapped it, but since it worked perfectly I thought no more about it.

Note that DC bias for the left and right EL84 push-pull stages passes through a similar, center-tapped output transformer which drives the "bass channel" speaker. DC bias for the whole shebang is injected at the center tap of the bass channel transformer and flows through its windings to the respective center taps of the left and right channel output transformers, which in turn feed the tube plates.

My guess is that the impedance of the left and right output transformers has been cut in half as compared with a "normal" arrangement with the drive DC going directly to the CT of the transformers. Likewise, the bass channel transformer would be half that of a normal EL84 push-pull output transformer; putting them together in series gives the impedance that the tubes expect to see. For operation with just the unit's three built-in speakers only the 16 ohm output is needed.

Apparently the set uses 16 ohm speakers- another oddity. Remote speakers would also have to be 16 ohms as well Re: Guild New Englander Bass Output Transformer Replacement by lorenzw » Oct Fri 30, pm I don't know if the following information will be particularly helpful, but I pulled my New Englander out from the wall and took at look at the output transformers.

The bass channel transformer is massive compared to the two side channel units. Each side channel output transformer is stamped "TAO Could this info be the plate resistance data for the transformers? As in, "Transformer, Audio Output, 2. It sort of fits the scenario that I proposed; except that if this is actually the plate resistance info it means that the side channel transformers are 3X the resistance of the center channel unit, not equal to it as I had guessed.

Note that 10K plate-to-plate load resistance is generally accepted as the correct value for 6V6 tubes configured in push-pull EL84 is essentially a miniaturized 6V6. A transformer specified for this should work well. For the latter, a ohm plate to plate load is listed. You would want half that for four tubes. Class A1 operation might benefit from a bit higher load impedance. In general, the 6BQ5 appears to run at higher currents and lower voltages than the 6V6, so lower impedance loads for the 6BQ5 are reasonable.

I am able to hear the radio from the output on the tuner going to another amp but would love to just use that amp like it was meant to be. I got the new bass transformer and sparks were flying in the rectifier tube so I disconnected the wire that comes out of the bass transformer to power part of the left channel and still sparks. I reconnected the left and disconnected the right and there was sound, nice sound with bass and treble working great. Now since the right channel area that seems to be the culprit I have to figure out what is causing the sparks when that channel is being powered If you guys have any leads please let me know.

Re: Guild New Englander Bass Output Transformer Replacement by lorenzw » Nov Thu 19, pm Check the right channel output transformer for a shorted primary winding or primary winding-to-frame short.

Often, small-value high-voltage caps are installed across the output transformer primary windings or from the output tube plates to ground in order to mitigate high back-EMF voltage surges from the transformer. Although no such caps are shown on the schematic, they might have been added as a running mod at the factory or by a previous technically-inclined owner who felt that they were desirable. Without the aforementioned caps, if someone pulled one of the right-channel EL84 tubes while the set was turned on, it's conceivable that your right channel output transformer could have internally flashed over and shorted.

However, that's just speculation. Since all audio output power flows through the bass channel transformer, a short in the right channel output transformer is probably the reason why your bass channel transformer went open in the first place. Re: Guild New Englander Bass Output Transformer Replacement by Tube Radio » Nov Thu 19, pm Have you replaced all the electrolytic capacitors along with all paper capacitors provided the stereo does use paper capacitors?


TTG-EL84SE - Tube output UL transformer [5kOhm] EL84 / 6V6 SE

At the time this manual was written, the Tubelab SPP has only been tested as a stand alone push pull amplifier. This means that a single SPP board is used with one power transformer and two output transformers to make a stereo HiFi amplifier. Other optional components like a filter choke or supplemental power supply capacitor may be added. I have done preliminary testing on using the board in single channel mono block configuration. This means that a single SPP board is used with one power transformer and one output transformer to make a single channel amplifier with higher the same power output as both channels combined on the stereo version.

Hoffman Amplifiers Tube Amp Forum, 6V6 vs EL84 OT impedance rating query. The original transformer had an 8K ohm primary with 15 ohm.

Panel Mount Audio Transformer 8 Ω, 16 Ω 3W


Need help with Output Transformer for EL I need help to identify the settings of the output transformer for the receiver in the figure below. Since the windings of primary were open, it is not possible anymore to measure the resistance and impedance of them. I am in doubt whether I should use 5k, 7k or other value to the transformer. Even the new output transformers are close in foot print to the originals and usually can be mounted in place of the originals. The attached schematics show the changes through October Recommend output transformer for 2xel84 15 watt amp. Actually the transformer I am using now I've built some great-sounding EL84 amps with the Add to cart.

Edcor DAP-202 OddWatt - ECC802S SRPP / EL84 (6BQ5) Push-Pull Tube Amp Transformer Bundle

el84 transformer impedance

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Before reading this it is highly recommended that you read the section on the Single Ended Output Stage. When large amounts of output power are required more than about 15W the push-pull output stage becomes the order of the day.

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The AC impedance of an output transformer, seen by the anode of a vacuum tube when a load a speaker in our case is connected to the secondary, depends on the ratio between the number of turns, of the primary and the secondary. Let n p and n s be respectively the number of turns of the primary and secondary. Let Z p , and Z s , be respectively the impedance seen at the primary and the impedance applied to the secondary that is the impedance of the speaker. We have that the ratio between the primary and secondary impedances is equal to the square of the ratio between the primary and secondary turns. More formally:. It is worth noting that, according to this equation, we can change the impedance, seen by the anode of the vacuum tube, which is the impedance of the primary of the transformer, by changing the impedance of the speaker.

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The SE & SEA do NOT include this screen tap as they were designed principally for high impedance triode tubes. High quality laminations, (M6) grain.

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Output Transformer Impedance question/verification please


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