I've built two TLSE amps, one for my wife with Electraprint outputs and Edcor PS and choke. The other one for me and had One Electron outputs and Edcor PS and choke. The Electraprints sounded a notch better than the One Electrons. I then changed my outputs to Hashimoto and they sounded better than the Electraprints. If I were to add Hashimoto PT and choke to my Hashimoto output amp, would there be a noticeable improvement?
You may see some improvement, little, or none at all. Either way the results will not be as dramatic as swapping the OPT's.
All of the audio signal must flow through the OPT to get to your speakers, and every OPT is imperfect, therefore the OPT has the largest influence on the sound quality in your amplifier.
The OPT must be designed to handle all frequencies from 20 Hz to 20 KHz, and treat them equally. It must also pass signals from microwatts to "many watts" and handle them equally. This a tough job and no OPT can do it perfectly. All OPT's are a tradeoff between it's ability to do this, and cost, size, weight, available materials, and the limits of physics (the BH curve is not linear).
If all capacitors were perfect, none of your audio signal would ever get to the choke or power transformer, so it should have little or no effect on the sound quality.
The power transformer only needs to work over a vary narrow frequency range, 50 to 60 Hz, or just 60 Hz. It does not need to be concerned with low level details since it only deals with "many watts." It does however have some influence over the sound, again since no transformer is perfect.
There are imperfections in a power transformer that can influence the sound.
The largest is regulation which is a bigger problem in a class AB amp. A transformer may produce 400 volts of B+ when the amp needs 50 mA of current, and 360 volts of B+ when the amp needs 300 mA of current. This variation in is not often specified, and will limit the power output of an amp, and possibly affect the sound quality of an amp since the B+ is not constant.
All chokes have a DC resistance since no wire is perfect. Larger DCR's also affect the regulation of the power supply. Power supply regulation in a class A amp is not as important as in class AB since the current drain of the entire amp is fairly constant, unless the amp is pushed to clipping, in which case it's not in class A any more....no the class A guitar amp guys don't get this.
All transformers will couple unwanted signals between the different windings. There are plenty of unwanted signals in your line power. This "noise" must be removed by the transformer and the power supply components in the amp. Some transformers do a better job than others, but none are perfect in this regard.
Anything that gets through the power transformer (a lot) must be removed by the power supply. The choke or any active regulators do the most here.
In reality everything from chassis layout to parts quality can affect the ability of an amp to reject "noise" pickup from the power lines, and the surrounding environment.
Real world worse case line noise test, plug an old style corded electric drill, the kind with brushes in the motor, into the same outlet or power strip as your amp. Do you hear any motor whine in your speakers when you pull the drill's trigger?
This is worse case since most of the noise is at an audio frequency. Many amps will fail this test. There are many unwanted signals on our power lines that get into an amp that are above the range of hearing, but can still create low level crud when blended together. LED and some CFL lighting, and switch mode power supplies like in TV's and computers are big offenders here.
Old school EI power transformers reject more of this than toroids due to their limited high frequency response.
All of the audio signal must flow through the OPT to get to your speakers, and every OPT is imperfect, therefore the OPT has the largest influence on the sound quality in your amplifier.
The OPT must be designed to handle all frequencies from 20 Hz to 20 KHz, and treat them equally. It must also pass signals from microwatts to "many watts" and handle them equally. This a tough job and no OPT can do it perfectly. All OPT's are a tradeoff between it's ability to do this, and cost, size, weight, available materials, and the limits of physics (the BH curve is not linear).
If all capacitors were perfect, none of your audio signal would ever get to the choke or power transformer, so it should have little or no effect on the sound quality.
The power transformer only needs to work over a vary narrow frequency range, 50 to 60 Hz, or just 60 Hz. It does not need to be concerned with low level details since it only deals with "many watts." It does however have some influence over the sound, again since no transformer is perfect.
There are imperfections in a power transformer that can influence the sound.
The largest is regulation which is a bigger problem in a class AB amp. A transformer may produce 400 volts of B+ when the amp needs 50 mA of current, and 360 volts of B+ when the amp needs 300 mA of current. This variation in is not often specified, and will limit the power output of an amp, and possibly affect the sound quality of an amp since the B+ is not constant.
All chokes have a DC resistance since no wire is perfect. Larger DCR's also affect the regulation of the power supply. Power supply regulation in a class A amp is not as important as in class AB since the current drain of the entire amp is fairly constant, unless the amp is pushed to clipping, in which case it's not in class A any more....no the class A guitar amp guys don't get this.
All transformers will couple unwanted signals between the different windings. There are plenty of unwanted signals in your line power. This "noise" must be removed by the transformer and the power supply components in the amp. Some transformers do a better job than others, but none are perfect in this regard.
Anything that gets through the power transformer (a lot) must be removed by the power supply. The choke or any active regulators do the most here.
In reality everything from chassis layout to parts quality can affect the ability of an amp to reject "noise" pickup from the power lines, and the surrounding environment.
Real world worse case line noise test, plug an old style corded electric drill, the kind with brushes in the motor, into the same outlet or power strip as your amp. Do you hear any motor whine in your speakers when you pull the drill's trigger?
This is worse case since most of the noise is at an audio frequency. Many amps will fail this test. There are many unwanted signals on our power lines that get into an amp that are above the range of hearing, but can still create low level crud when blended together. LED and some CFL lighting, and switch mode power supplies like in TV's and computers are big offenders here.
Old school EI power transformers reject more of this than toroids due to their limited high frequency response.
Thanks for the thorough explanation, George. I think I'm gonna go ahead and spring for a Hashimoto PT and choke. Sort of an all in proposition. They list two PT for a 300B amp, but I'm not sure which one to go with. Here's the specs......PT-240.....480V-420V-240V-0-240V-420V-480V/0.17A......0-2.5-5V/5.5A(x2), 6.3/3A, 5V/3A....or....PT-220....380V-320V-0-100V-320V-380V/0.2A.....0-4V-5V/3A(x2).....0-6.3V-10V/2.5A....5V/3A. Are either of these viable?
Apparently soundtradition.com , here in the states, has Hashimoto PTs with variable V primaries. I know the ones from accousticdimentions.com in Japan are 100V.SOUND-TRADITION.COM
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I built a Tubelab SPP with Hammond transformers throughout and really enjoyed it.
I recently decided to build an upgraded version, where I'm using Hashimoto power and output transformers (with a Hammond 193 series choke as the Hashi was very expensive)
I purchased them from Mr. Isao which is the US distributor and the PT was 120V (has a "B" suffix)
Although it depends on your operating point, I'm pretty sure the PT-270 could work nicely?
640VCT @ 390mA DC
2x 6.3V @ 5A + 6.3V @ 2.5A (you can bridge them)
5V @ 3A
I think the PT-160 can also work well if you don't bias the 300B over ~80mA
For the 6.3V on the PT-160, you can bridge all 3 terminals for 8.5A
I recently decided to build an upgraded version, where I'm using Hashimoto power and output transformers (with a Hammond 193 series choke as the Hashi was very expensive)
I purchased them from Mr. Isao which is the US distributor and the PT was 120V (has a "B" suffix)
Although it depends on your operating point, I'm pretty sure the PT-270 could work nicely?
640VCT @ 390mA DC
2x 6.3V @ 5A + 6.3V @ 2.5A (you can bridge them)
5V @ 3A
I think the PT-160 can also work well if you don't bias the 300B over ~80mA
For the 6.3V on the PT-160, you can bridge all 3 terminals for 8.5A
Thanks for the info. Have you built the SPP with the Hashimotos yet? I'd sure like to hear your impressions. I built a SPP with Antec power and old Sansui 1000 reciever outputs, using EL86/6CW5 tubes and it sounds good. I'm kinda into this SET thing right now and the Hashi outputs on the TLSE made a marked difference in the sound quality.... that and choice of output tubes. Hard to describe...more detail and a tone I can't stop listening to.
The Hashimoto SPP is assembled in the chassis but not wired yet... I'm hoping to complete that within the next week or so.
The build quality is amazing, but you probably know that from the OPT's you already have.
I've built a TSE in the past with ISO (ex-Tango) transformers, also very good but I suspect a notch below the Hashimoto.
The biggest difference when going from a Hammond/Edcor PT to the ISO was that it was super quiet and cool after hours of operation. No buzz or noise at all, whereas I could hear the Edcor buzz from a few feet away. The amp was also dead quiet even with my ear near the speaker, so I believe that choke was better at filtering than the open-frame I used prior to it.
To give you another option to consider, I just finished another TSE with Lundahl output transformers, the LL1663/50mA. I originally bought these for a single-ended EL84 but ended up using something else for that build.
I chose the operating point of 350V B+, 50mA per 300B, which is limited to about 6-7W but has low THD. I used a Hammond 372JX and have been really pleasantly surprised by it. It also runs very cool and quiet compared to the 370HX I tried in the past.
I think the main reason is the 8A rating on the 6.3V winding. I believe a minimum of 6A should be used because of the DC filaments. 2* (1.25+1.25+0.3+0.3).
The build quality is amazing, but you probably know that from the OPT's you already have.
I've built a TSE in the past with ISO (ex-Tango) transformers, also very good but I suspect a notch below the Hashimoto.
The biggest difference when going from a Hammond/Edcor PT to the ISO was that it was super quiet and cool after hours of operation. No buzz or noise at all, whereas I could hear the Edcor buzz from a few feet away. The amp was also dead quiet even with my ear near the speaker, so I believe that choke was better at filtering than the open-frame I used prior to it.
To give you another option to consider, I just finished another TSE with Lundahl output transformers, the LL1663/50mA. I originally bought these for a single-ended EL84 but ended up using something else for that build.
I chose the operating point of 350V B+, 50mA per 300B, which is limited to about 6-7W but has low THD. I used a Hammond 372JX and have been really pleasantly surprised by it. It also runs very cool and quiet compared to the 370HX I tried in the past.
I think the main reason is the 8A rating on the 6.3V winding. I believe a minimum of 6A should be used because of the DC filaments. 2* (1.25+1.25+0.3+0.3).
