So, if measuring the voltage drop really is just measuring the difference between the legs of a resistor, which I did last night, then even the ones which are seeing 253v to ground are dropping the voltage very little. So, IF voltage drop is ONE of the main ingredients in the working voltage rating recipe, then the 1/4 watt resistors are just fine where they are--at least in this regard.
As for "magic parts" --no. Not looking for magic parts. But some small changes in flavor. This is a complete rebuild that won't even touch the original PC board.
Quite often the bog standard industrial part sounds best, in my experience. Frustratingly, I have also found that that boutique thingamabob with gold printing on it does just the right thing in a given circuit.
It is, however, always true that a good circuit design always trumps a mountain of bourgeois name-brand Whatchmacallums. I worked at a fancy HiFi store in the 90s and we used to get in lots of gadgets that advertised right on the box whose wire or capacitors or connectors they used. Very few of them weren't bested by a beat-up receiver from the 70s.
But (in my own defense) I would hardly say I was wasting money on a $.45 part VS. a $.20 part. Especially when there are so few.
As for "magic parts" --no. Not looking for magic parts. But some small changes in flavor. This is a complete rebuild that won't even touch the original PC board.
Quite often the bog standard industrial part sounds best, in my experience. Frustratingly, I have also found that that boutique thingamabob with gold printing on it does just the right thing in a given circuit.
It is, however, always true that a good circuit design always trumps a mountain of bourgeois name-brand Whatchmacallums. I worked at a fancy HiFi store in the 90s and we used to get in lots of gadgets that advertised right on the box whose wire or capacitors or connectors they used. Very few of them weren't bested by a beat-up receiver from the 70s.
But (in my own defense) I would hardly say I was wasting money on a $.45 part VS. a $.20 part. Especially when there are so few.
I didn't think you were. I was just trying to explain a bit of why some of the design choices were made. The TSE was designed first and it was never intended to be a DIY amp. I made one for myself, and then one for a friend.....and before long I couldn't make enough so I drew up some crude plans and ordered a stack of boards. Most of my friends were engineers I worked with. During a beer and BS session, we discussed a simpler design that anyone could build, and the idea of a website for all of our ideas. Tubelab and the SSE was born.....then the layoffs started, and within a couple of years I was the only one of the original group left.
I might be one of those who tend to exceed a rating or two. All of the circuits I publish are tested to extremes beyond those any reasonable user should subject them too. Even my DHT amps are subjected to the guitar amp test. I want to find any weakness before the user does, and fix them. I do the same with other peoples designs. Pete Millett published a design for an 18 WPC sweep tube amp. I bought his board stating that I would be unhappy if I didn't get at least 50WPC. That turned out to be an understatement. I got 250WPC at the edge of meltdown, so I scaled it back to 125 WPC and published the plans. Several builders made the 125 WPC design and they worked out well.
I didn't realize that you wanted to do a PTP version in your original post. A few PTP SSE's have been built and most worked out OK. There was one builder who couldn't get the hum out of the amp, and was rather upset that I couldn't troubleshoot something that I had never seen.
The key to building a hum free SSE is to try to copy the grounding scheme used in the PCB. The board uses a common "star" ground point at the negative end of the big power supply cap. Notice a separate PCB runner going out from that point to the preamp and power amp sections. The board, and thus the entire amp is connected to the chassis through the input jacks. The power input (IEC jack) is also grounded to this point through the power supply connector.
The CCS IC will oscillate if you give it a chance. Solder the resistors directly to the IC pins with short leads on the resistors. I have built the CCS circuit on a small piece of perf board for convenience in PTP designs. I often substitute a 1K trimmer pot with a 100 ohm resistor in series for the 330 ohm resistor for current adjustment. The CCS chip passes a constant current and by its very nature provides a 50 db reduction in hum to the 12AT7. I doubt that additional power supply filtering could improve this.
You might be able to find resistors with lower noise than the parts I chose. They would definitely be a better choice in a preamp or phono stage, but you might not hear any improvement in a power amp.
As stated, using an audiophile quality coupling cap may offer some sonic benefit. I have used a few different $5 to $10 caps in some of my builds. They do sound different than the $1 caps, but some of my friends have different opinions as to which sounds "better".
Also stated, the OPT will make the biggest difference in the sound of your amp. The good budget choice is the big Edcor CXSE 25 series. The best OPT that I have ever bought were the Electra Prints in my TSE.
Thanks for your replies!
Yes. I am planning to employ a star grounding scheme, or at least a quasi-star ground. The amp built with the PCB is dead quiet even with out a chassis (I still have is screwed to a piece of plywood with spacers under the board.)
I emailed Electra Print when I was first putting together the amp a while back and he wanted over $200 a piece for 5k 10w OPTs with a single secondary and UL tap. I guess if I left out the UL tap it could be a little cheaper. I settled for the Transcendars. Would the ELectra Prints be worth the $400? Are they $250 better than the Transcendars? (Sorry. That is very subjective question.)
BTW- I have been reading through your website. Lot's of good reading there. You have a very clear and straightforward way of explaining things.
Best,
John
Yes. I am planning to employ a star grounding scheme, or at least a quasi-star ground. The amp built with the PCB is dead quiet even with out a chassis (I still have is screwed to a piece of plywood with spacers under the board.)
I emailed Electra Print when I was first putting together the amp a while back and he wanted over $200 a piece for 5k 10w OPTs with a single secondary and UL tap. I guess if I left out the UL tap it could be a little cheaper. I settled for the Transcendars. Would the ELectra Prints be worth the $400? Are they $250 better than the Transcendars? (Sorry. That is very subjective question.)
BTW- I have been reading through your website. Lot's of good reading there. You have a very clear and straightforward way of explaining things.
Best,
John
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