output transformer for a heathkit w5m
- Thread starter cocobolo95
- Start date
soundmotor
super modified
Well done, that settles it for me right there. 16309 then 16458 for the W-5M OT chronology.
Ditto. I got confused for a bit.
Driving this amp with TungSol KT66 using only 900mA heaters instead of the regular 1.3A did help the PT heat.
Also increasing the cathode resistor a bit helps too as with higher gm tubes you can slightly red plate the power tubes.
Other than that, this amp is really audiophile material, very refined and detailed top to bottom. A real sweet amp.
Driving this amp with TungSol KT66 using only 900mA heaters instead of the regular 1.3A did help the PT heat.
Also increasing the cathode resistor a bit helps too as with higher gm tubes you can slightly red plate the power tubes.
Other than that, this amp is really audiophile material, very refined and detailed top to bottom. A real sweet amp.
cocobolo95
New Member
Brice, when you mention increasing the cathode resistors, are you meaning increasing the wattage & peak voltage capability. Or are you saying to add more resistance to the circuit. Or is it both?
I'm pretty new to all this, so more detailed explanations are needed.
Also, can someone make a list of the needed changes to make the w5m reliable. I plan on using this as my first line amp. I'm taking amp down to a bare chassis and will rebuild it. This is not for resale as I plan on keeping it till the end.
Because I don't know screen printing, I plan on making water slide decals of the writing on the amp. Does anyone happen to know what font is used for "Heathkit" on the amp. Ive found one font in my photo shop program that comes close to correct. But the small "k" is completely different.
Finally, is there a certain number of posts you must have to add an avatar pic? I can't seem to find anyway to add one.
I'm pretty new to all this, so more detailed explanations are needed.
Also, can someone make a list of the needed changes to make the w5m reliable. I plan on using this as my first line amp. I'm taking amp down to a bare chassis and will rebuild it. This is not for resale as I plan on keeping it till the end.
Because I don't know screen printing, I plan on making water slide decals of the writing on the amp. Does anyone happen to know what font is used for "Heathkit" on the amp. Ive found one font in my photo shop program that comes close to correct. But the small "k" is completely different.
Finally, is there a certain number of posts you must have to add an avatar pic? I can't seem to find anyway to add one.
Increasing the wattage of a resistor will not decrease the amount of heat it generates, that is a function of its resistance value and the current flowing through it - P = I2 (Squared) x R. A higher wattage resistor has more volume and surface area to dissipate heat or is built from materials to tolerate that heat without failure, or both.
If the ambient temperature of the work environment is lower than the resistor, or has adequate airflow or heatsinking, then the resistor can radiate its heat and wattage load effectively, up to its rated temperature or wattage value. I agree with raising them into the surrounding air if possible assuming you're not close to any metal surfaces like the bottom plate or have excessive lead lengths which can sometimes act as antennas.
If the ambient temperature of the work environment is lower than the resistor, or has adequate airflow or heatsinking, then the resistor can radiate its heat and wattage load effectively, up to its rated temperature or wattage value. I agree with raising them into the surrounding air if possible assuming you're not close to any metal surfaces like the bottom plate or have excessive lead lengths which can sometimes act as antennas.
Great job DC, I've been looking for a definitive answer on dating the transformers myself, sure looks like I got it backwards, either from memory inversion or the Heath guy said it backwards or just plain got it wrong. I even sent for a book on heath history, which hasn't arrived yet. Anyway, good going, I'm a big fan of the historical aspects of audio. I think I have 4 or 6 W5's, plus a couple of 16309's that need rewinding. I had about 20 of the amps a few years ago but a Detroit guy came over and bought a dozen of them for a project.
I'm curious as to how the custom heyboer transformer of the peerless s265 compares to an original one.
Heyboer built 2 stancor a8054 clones for my kt66 Williamson amplifiers and they turned out great. I actually prefer the stancor a8054 over the stancor a8072 ultra linear.
Heyboer built 2 stancor a8054 clones for my kt66 Williamson amplifiers and they turned out great. I actually prefer the stancor a8054 over the stancor a8072 ultra linear.
I am curious too. To do it right, will require a significant amount of interleaving of the windings, as that is how the original was manufactured. That process takes much more time (and is therefore much more costly) than simply winding a complete primary winding, and then a complete secondary winding.
Multi -- Did you ever pass a 10 kHz square wave signal through your Williamsons to check the supersonic performance of your Heyboer transformers (overshoot, ringing, stability, etc.)? That would really tell the story as to how well they copied the original design. The A 8072 is a more difficult transformer to reproduce as its UL operation requires very tight coupling between the primary halves.
Dave
Multi -- Did you ever pass a 10 kHz square wave signal through your Williamsons to check the supersonic performance of your Heyboer transformers (overshoot, ringing, stability, etc.)? That would really tell the story as to how well they copied the original design. The A 8072 is a more difficult transformer to reproduce as its UL operation requires very tight coupling between the primary halves.
Dave
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trobbins
Super Member
Stanko,
I had some feedback from Patrick Turner on your tear-down photo of the 16309 output transformer. He has never come across the commercial use of Nickel lams (if that's what they are) in a core except by Audio Note in Japan that appear to have used 50% mix with GOS for SE application, where the SE imposed gap would manage the higher u of the Ni lams - the result apparently being less variation in winding inductance with applied voltage and frequency. Perhaps the use of Nickel is why the instruction manual makes a big issue about DC balancing the windings, to reduce the chance of the Ni lams saturating. It was also noted by others that those lams would have been low Ni % lams, and that not everyone viewed their use with 100% confidence.
Patrick's view of the supposed balancing cap was that typical differences in capacitance between primary sections, no matter how typical 5P + 4S windings were interleaved and configured, didn't showed through in any tangible loss of performance for class AB, let alone class A. And adding any extra shunt C would only degrade phase shift. I guess at the time circa 1955 it made sense - perhaps just even for the manufacturer to meet a 'design spec' for balanced winding capacitance.
Tim
I had some feedback from Patrick Turner on your tear-down photo of the 16309 output transformer. He has never come across the commercial use of Nickel lams (if that's what they are) in a core except by Audio Note in Japan that appear to have used 50% mix with GOS for SE application, where the SE imposed gap would manage the higher u of the Ni lams - the result apparently being less variation in winding inductance with applied voltage and frequency. Perhaps the use of Nickel is why the instruction manual makes a big issue about DC balancing the windings, to reduce the chance of the Ni lams saturating. It was also noted by others that those lams would have been low Ni % lams, and that not everyone viewed their use with 100% confidence.
Patrick's view of the supposed balancing cap was that typical differences in capacitance between primary sections, no matter how typical 5P + 4S windings were interleaved and configured, didn't showed through in any tangible loss of performance for class AB, let alone class A. And adding any extra shunt C would only degrade phase shift. I guess at the time circa 1955 it made sense - perhaps just even for the manufacturer to meet a 'design spec' for balanced winding capacitance.
Tim
I am very suspicious about anyone rewinding so-called identical output transformers. Output transformers from the "glory days" of audio were basically hand made and very time intensive. There is a lot of tagging wires, cutting winding wires, resoldering all the ends in correct order after winding, etc. that goes on in one because of the interleaving of the primaries and secondaries. The amount they charge for these transformers doesn't add up to the amount of labor needed to properly interleave them. I personally think many of them, if not all, are wound conventionally, with no interleaving or interweaving, as we used to call it years ago. JMHO.....
cocobolo95
New Member
Can we get back to the original reason I made this thread. Does anyone know a good replacement output trans for the w5m. One that doesn't cost more than amp is worth. And one that is readily available.
The rest of the service upgrade document for the w5m would be greatly appreciated also.
The rest of the service upgrade document for the w5m would be greatly appreciated also.
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cocobolo95
New Member
The 10k was info I gleaned off a write up on the Williamson amp and Heathkit lit. I'm not worried about the ot being the original size. I can fit a 4.5" by 4.5" ot onto the chassis. While an original type potted ot would look good, it is not necessary.
Edcore has 10K output transformers listed on their site. The only worry I have is the 40% screen grid taps this ot has. The original ot has a 50% screen grid tap, from what I've read.
While I've read that kt66 tubes can use the lower plate resistance, I've also read that Williamson type amps like the higher 10K plate resistance.
Edcore has 10K output transformers listed on their site. The only worry I have is the 40% screen grid taps this ot has. The original ot has a 50% screen grid tap, from what I've read.
While I've read that kt66 tubes can use the lower plate resistance, I've also read that Williamson type amps like the higher 10K plate resistance.
Shadowdog
Super Member
Best to find a good used one if you want the same sound quality! You pay for what you get, so you may need a pair of low cost ones
so the difference isn't so obvious. Just have patience and likely a good stock replacement will show up for a fair price! A fair number of those amps were made!
so the difference isn't so obvious. Just have patience and likely a good stock replacement will show up for a fair price! A fair number of those amps were made!
cocobolo95
New Member
I've read that 30,000 were made during it's run.