Antek transformer 2 0

Will provide complete parts list upon request. The PV9 impressed me with its truthfulness. They recorded samples and allowed people to have a listen. The SP14 is a well optioned preamplifier having a phono stage with sufficient gain to accomodate low output moving coil cartridges.

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Content:

• ARTICLE N°
• Pultec EQP1A power transformer, which one ?
• AS-3224 Datasheet, Equivalent, Toroidal Transformers.
• diytube.com
• 2a3 tube vs 300b
• 15V 30VCT Power Transformer Antek AS-1215 100VA 15V
• Sp14 preamp build
• Inexpensive HV transformers for your HB Linear Amplifier
• What power transformer to buy
• Antek Toroidal power transformer for Step-up, Measurements (part 1/2)

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ARTICLE N°

Thus, I set about making a SPICE curve tracer and I took the resulting plate curves and overlaid them upon a set of curves from an actual curve tracer.

Why not? As I have pointed out many, many times before, all SPICE triode models are fundamentally flawed, as they all treat the triode as if it were a variable current source, which it simply isn't. A triode is variable resistance.

In the absence of cathode-to-plate voltage, a triode draws zero current. This is not necessarily true with SPICE models, which often show triodes producing current much like batteries produce voltage. First, let's look at the actual curve-tracer plate lines. Of course, this set of plate curves applies only to one individual 12AU7. Nonetheless, it looks like a 12AU7. Four decades ago while searching through a college library's electrical-engineering books I found an amazing book.

It was a collection of plate curves for many of the most popular tubes, such as the 12AX7 and 12BH7… What made it interesting was the way the curves were generated: rather than trace a set of plate curves for one triode, 10 triodes were wired in parallel and this grouping underwent curve tracing; afterwards, the current scale was divided by ten.

In other words, the set of curves was an average of the ten individual triodes, so possibly not one triode matched the resulting curves, but the curves were fundamentally a more accurate representation of the triode in general. Not so good. Note that as we move away from the 0V plate line, the SPICE model progressively fails to match reality, as the model assumes a constant amplification factor. Bad as this is, it's actually worse, as I edited out the SPICE model's most egregious failing: increased current flow with greater negative grid voltages.

The V-grid-voltage plotline was made bold to show how the model egregiously screws up. An actual 12AU7 with a cathode-to-plate voltage of 0V and a grid voltage of V does not draw 27mA of plate current; it does not draw any current.

This is the stuff from which perpetual-motion machines are made. What seems to have gone wrong is that the model attempted to account for positive-grid current flow but failed. No insane folding back, but we do see the same assumption of a constant amplification factor.

The next is by Francesco Pintavalle. The resulting plate curves are much better than those by the previous SPICE model and, once again, we see the same assumption of a constant amplification factor. My model tracks fairly well the curve-tracer plots, departing only slightly at the bottom, where the triode nears cutoff. Speaking of which, here is my triode-model formula:. Note how I based the formula on the famous Childs formula, but normalized or referenced to the grid voltage Vg and added three new variables, A, B, and C.

Essentially, to get my triode math model to work in the SPICE engine requires creating a new class of device within the SPICE source code, much like the existing MOSFET class, which would contain all the fundamental aspects of a triode, such as its functioning as a diode as current only flows from the cathode to the plate when the plate is more positive than the cathode.

With an expanded SPICE source code, triode models would contain such features as the potential for positive-grid current flow and inverted operation, wherein we treat the grid as the plate and the plate as the grid.

Another Split-Load Phase Splitter Version After making my last post, I had this haunting feeling that I forgot to include another version of the split-load phase splitter that delivered equal and in-phase PSRR from both outputs. I went hunting. Well, I found a more complicated version of what I sought. Since the circuit is somewhat complicated, we will work our way up to it. The first stage, the input stage, is a simple grounded-cathode amplifier, based on a 12AU7 triode.

If the cathode resistor had been bypassed with a large-valued capacitor, the leaked power-supply noise would be even less. One workaround is to shunt the 43k plate resistor with a The gain drops to about ten 20dB and The next stage is a split-load phase splitter based on a 12AX7 triode.

Both outputs leak, in phase, Obtaining perfect balance is key to making the second Aikido mojo trick work. The last stage is a differential amplifier based on an ECC The addition of the 1.

Since even this Aikido mojo trick didn't result in a deep power-supply-noise null, we should use an RC filter with a large-valued capacitor to first reduce the ripple before the Aikido mojo takes over. Click on schematic to see enlargement. This differential-amplifier Aikido-mojo technique can also be used with a differential amplifier cascade. The input differential amplifier sees a constant-current source at its tied cathodes, so almost all of the power-supply noise will appear at the two plates.

The added The resulting PSRR enhancement dB is great, as the two differential amplifiers in cascade would otherwise deliver power-supply noise gain, not attenuation. The downside to this noise-reduction technique is that it requires a large-valued capacitor to terminate the added resistor What if both differential amplifiers get their own constant-current source cathode loading?

In this configuration, we forgo the large-valued capacitor and low-valued resistor and place a shunting resistor across the constant-current source. The total gain for this circuit with an unbalanced input signal is 42dB , which should be enough to drive a tube-based, push-pull output stage, even with B output tubes. Negative feedback can be applied at the input stage's grounded grid. If the output tubes require only a quarter of the gain, then the feedback ratio is or 12dB.

In theory, the shunting resistor would equal half the plate resistor value i. If we now use an RC filter with a large-valued capacitor to reduce the ripple prior to the Aikido mojo, we can achieve some stellar PSRR figures. A question often asked is, Which is better: a single RC filter with a large-valued capacitor and large-valued resistor or two RC filters in cascade, each holding half the values of the single RC filter?

On the other hand, in a circuit that experiences large unbalanced current swings, the higher impedance will become an issue. In other words, the true answer is it depends. There is still one trick we can add. We can more than double this -3dB frequency by cross-coupling two 2pF capacitors from plate to opposing grid, which will help neutralize the ECC99 triode's Miller-effect capacitance.

Be careful, as too high a capacitor value will cause peaking and possibly oscillation. Of course, we may not desire such high-frequency bandwidth. By the way, all these techniques assume that well-matched triodes are used and that tight-tolerance resistors are used. If we seek the largest possible symmetrical output voltage swings from a differential amplifier with a constant-current source cathode loading and a given plate resistor value, the following formula comes in handy.

AnTec Output Transformers Over the last two decades, I have bought many toroidal power transformers from AnTek ; and over the last three decades, I have bought many aluminum enclosures from AnTec's sister company, Par-Metal. Fairly recently, AnTek has offered output transformers for tube-based power amplifiers, with push-pull output transformers that range from 10W to W and a 30W single-ended output transformer. All are flat toroidal designs and the prices are more than reasonable. The transformers that interested me most are the 10W and 15W, as they offer the most extended high-frequency output.

In addition, they would work well in the circlotron variation that I have shown here many times before, the last time being in post , with output tubes; and with output MOSFETs in post If only to read the first paragraph, which is a doozy, post is also worth reviewing.

Normally, each channel of a circlotron amplifier holds two floating power supplies; not this variation. In fact, we could use one high-voltage power supply to power four channels of output. The secret is that the large-valued capacitors take the place of the floating power supplies.

In terms of AC signal, the large-valued capacitors are effectively dead shorts; in terms of DC currents, they do not exist. The use of two output transformers per channel not only simplifies the power supply, it allows us to use better sounding output tubes, such as the 2A3, EL34, EL84, KT88, B… and many fewer of them. The DC-coupled OTL circlotron demands low-voltage, high-current tubes, such as the 6AS7 and 6C33, and many more of them, as an 8-ohm load is an insanely low impedance for any tube to drive directly.

It takes eight 6AS7 twin-triode tubes to deliver 60W of output into an 8-ohm loudspeaker in the OTL circlotron, whereas a 60W transformer-coupled circlotron requires only two KT88 output tubes. In addition, transformer coupling is inherently safer. If an output tube arcs from cathode to plate, the output transformer might be damaged, but the speaker is safe. In an OTL power amplifier, the speaker will go up in smoke.

If we use two 15W output transformers in this transformer-coupled circlotron, we can get 30W of output, as each output transformer will deliver half the output current, but the same output voltage as a single 30W output transformer would. What gets slightly confusing to many tube fanciers is that we must quarter the output transformer's primary impedance. In a conventional transformer-coupled, tube-based, push-pull power amplifier that runs in class-B or class-AB, the load each output tube sees at full output is one quarter the nominal plate-to-plate impedance.

For example, a 4k primary impedance drops to 1k, once the other output tube cuts off. How is this possible?

Once the output stage leaves its class-A window of operation, leaving only one output tube conducting, only half of the output transformer's primary is engaged. Thus, the winding ratio is halved, as the center-tap cuts the primary winding in half, which results in a quartering of the impedance ratio.

An output transformer's impedance ratio is equal to its winding ratio squared. In the transformer-coupled circlotron, the winding ratio is never quartered; the load impedance remains constant even as the output stage leaves class-A operation, as the entire winding is always engaged.

Not good, if the primary impedance is too high. Too high a primary impedance will require much larger plate-voltage swings to deliver the same amount of output power. Crazy high.

So, how do we quarter the impedance ratio of an existing output transformer? We use two output transformers and place their secondaries in series, which will effectively halve the winding ratio and quarter the impedance ratio.

One way to look at it is to see that effectively each secondary sees a 4-ohm load, and the two primaries are effectively in parallel, so the halved primary impedance gets halved again, leaving a quarter of the original ohm load impedance. What about 4-ohm loudspeakers? We must arrange the secondaries differently. What about ohm loads? Sorry, there is no arrangement that works with ohm loudspeakers, as the secondaries would need ohm output taps. Okay, it's time to pull back and ask ourselves why we should bother with this two-output-transformer circlotron rather than use a single 30W output transformer in a conventional push-pull power amplifier arrangement.

Pultec EQP1A power transformer, which one ?

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AS-3224 Datasheet, Equivalent, Toroidal Transformers.

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2a3 tube vs 300b

Thus, I set about making a SPICE curve tracer and I took the resulting plate curves and overlaid them upon a set of curves from an actual curve tracer. Why not? As I have pointed out many, many times before, all SPICE triode models are fundamentally flawed, as they all treat the triode as if it were a variable current source, which it simply isn't. A triode is variable resistance. In the absence of cathode-to-plate voltage, a triode draws zero current. This is not necessarily true with SPICE models, which often show triodes producing current much like batteries produce voltage.

15V 30VCT Power Transformer Antek AS-1215 100VA 15V

QRZ Forums. A HV linear amp transformer is very expensive. Transformers that are more reasonable in cost are Antek Transformers in NJ. It is rated at va on 60Hz power. Using a voltage doubler it produces about volts under load and is excellent for a pair of B tubes. Placing the two windings in series makes about same voltage using a bridge rectifier. Transformer includes two 6. It will produce about volts using a voltage doubler or bridge rectifier with the two windings in series and will support a watts PEP output amplifier with a pair of Z or high power ceramic tube such as a 3CX

Sp14 preamp build

Packaging should be the same as what is found in a retail store, unless the item was packaged by the manufacturer in non-retail packaging. They are specially designed to work on all standard V or V at 50Hz or 60Hz. The dielectric test is more than V in between primary and secondary coils.. See the seller's listing for full details.

Inexpensive HV transformers for your HB Linear Amplifier

CRM Cloud Point appr. Cup, brass. Pressure regulator, KCP, treaded - vaporizer. Valve, rotary, 6-port.

What power transformer to buy

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Antek Toroidal power transformer for Step-up, Measurements (part 1/2)

He also uses a pair of the 21st century Maida in one of his amps. A new SP14 preamp. The pre-amplifier detailed in this article was created to run using at 10V supply.