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ratbagp
PostPosted: April 5th, 2021, 5:27 pm 
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Posts: 499
It reminds me of the LSES and the 'flywheel effect' that was talked about on the Tube DIY Asylum several years ago.

https://db.audioasylum.com/mhtml/m.html?forum=tubediy&n=236840&highlight=flywheel&search_url=%2Fcgi%2Fsearch.mpl%3Fforum%3Dtubediy%26searchtext%3Dflywheel

More about LSES and flywheel at
https://deathtube667tubeamps.com/flywheel-or-lses-filter%3F

FWIW, years ago I built an LSES power supply and after a few weeks, substituted a 10H 300 ma choke for one of the Triad c40x chokes. It sounded like a damper was muffling the sound.

ray
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FerdinandII
PostPosted: April 5th, 2021, 5:39 pm 
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Joined: April 22nd, 2013, 12:58 pm
Posts: 293
You would think so. It's hard to imagine that a phono preamp would see any impact.
It's all class A, pretty much a constant load on the PSU, so..... why did it matter? :confusion-confused:
I'll leave it to the dueling astrophysicists....... :violence-duel:


DaveR wrote:
If the transformer is capable of providing the amount of current the circuit needs isn't it the filter caps that determine the impedance of the power supply? Instantaneous current is provided by the caps, not the transformer.
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Pelliott321
PostPosted: April 5th, 2021, 6:37 pm 
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I have had a couple of TS products and spent many hours involved with their forums.
The tweak most often talked about was the minimum size power transformers.
TS always fought back saying you only need a transformer for what is needed to drive the circuit.
I think most agree this is not the best for maximum performance, maybe not cost effective, but we all have to decide whether the cost is worth the gain in performance
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SoundMods
PostPosted: April 5th, 2021, 10:26 pm 
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Location: Parkville, Maryland
FerdinandII wrote:
You would think so. It's hard to imagine that a phono preamp would see any impact.
It's all class A, pretty much a constant load on the PSU, so..... why did it matter? :confusion-confused:
I'll leave it to the dueling astrophysicists....... :violence-duel:


DaveR wrote:
If the transformer is capable of providing the amount of current the circuit needs isn't it the filter caps that determine the impedance of the power supply? Instantaneous current is provided by the caps, not the transformer.

Paul McGowan of PS Audio learned that lesson the hard way. When he was developing a solid-state pre-amp many decades ago his development prototype was ready for the production prototype. The production prototype sounded quite different in that the sound was flat and not dynamic. What was the difference? The production prototype's power supply was sized for the expected load required -- the development prototype was powered with a salvaged power-amp. power transformer -- larger by a factor of ten.

My own experience with a PS Audio 5.5 pre-amp mirrored that event. The 5.5 came stock with a 250-va transformer (already over-sized) and a 500-va transformer was offered as an option. After living with the pre-amp I scraped together the cash to spring for the 500-va transformer. The sound quality improvement was not subtle by any stretch of the imagination. Only the transformer changed. The bridge rectifiers, storage caps, and regulation remained the same as those goodies were all on the main pre-amp PC board.

Size does matter. ;) I would venture a guess that keeping up with the storage capacitors was easier with the larger transformer. I have noticed that too many DIY types (or even manufacturers for that matter) will load up a design with a lot of storage and not consider the power transformer's ability to feed that constant load (charging current) and to add insult-to-injury -- not consider the storage capacitor's ability to handle ripple current. If a capacitor has to deal with ripple current that it is not designed for -- that is a recipe for failure. It will overheat internally and cause premature failure of the dielectric.

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Grover Gardner
PostPosted: April 6th, 2021, 11:13 pm 
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Joined: June 4th, 2013, 2:39 pm
Posts: 497
SoundMods wrote:
FerdinandII wrote:
You would think so. It's hard to imagine that a phono preamp would see any impact.
It's all class A, pretty much a constant load on the PSU, so..... why did it matter? :confusion-confused:
I'll leave it to the dueling astrophysicists....... :violence-duel:


DaveR wrote:
If the transformer is capable of providing the amount of current the circuit needs isn't it the filter caps that determine the impedance of the power supply? Instantaneous current is provided by the caps, not the transformer.

Paul McGowan of PS Audio learned that lesson the hard way. When he was developing a solid-state pre-amp many decades ago his development prototype was ready for the production prototype. The production prototype sounded quite different in that the sound was flat and not dynamic. What was the difference? The production prototype's power supply was sized for the expected load required -- the development prototype was powered with a salvaged power-amp. power transformer -- larger by a factor of ten.

My own experience with a PS Audio 5.5 pre-amp mirrored that event. The 5.5 came stock with a 250-va transformer (already over-sized) and a 500-va transformer was offered as an option. After living with the pre-amp I scraped together the cash to spring for the 500-va transformer. The sound quality improvement was not subtle by any stretch of the imagination. Only the transformer changed. The bridge rectifiers, storage caps, and regulation remained the same as those goodies were all on the main pre-amp PC board.

Size does matter. ;) I would venture a guess that keeping up with the storage capacitors was easier with the larger transformer. I have noticed that too many DIY types (or even manufacturers for that matter) will load up a design with a lot of storage and not consider the power transformer's ability to feed that constant load (charging current) and to add insult-to-injury -- not consider the storage capacitor's ability to handle ripple current. If a capacitor has to deal with ripple current that it is not designed for -- that is a recipe for failure. It will overheat internally and cause premature failure of the dielectric.


I'm with Walt here. I would *always* overrate the power iron. The whole circuit relaxes and presents and ease of presentation. One problem with older tube amps, like Heathkit and Eico, is that the power transformers are juuuuuust enough. The power trannies tend to overheat, which is detrimental to the whole amp. Beef up the power iron and these amps take on w whole new life.
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Pelliott321
PostPosted: April 7th, 2021, 8:44 am 
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A couple years ago I built a little SS phono preamp kit from DIYAUDIO that was designed to run on batteries. I was interested because I wanted to see the differences between 9 Volt batteries, SLA, and LiPo would sound like.
The 9 v batteries was horrible. The big SLA was a bit better and the LiPo was the best, probably because the internal resistance of the LiPo was the lowest.
The less than $100 board still was not very musical so I tried using a leftover shunt regulated PS from Twisted Pear that supplied mort than 10 times the required current and the sound was great.
In fact that phono preamp is living in a friends Uber system replacing a $6500 Ron Southerland phono and my friend could not be happier.

But....

My friend just cannot live with a cigar box phono preamp in his Uber-system so at his direction I am building for him an AN L3 phon preamp at almost $2k for him. Will see how this compares to the cigar box.
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SoundMods
PostPosted: April 7th, 2021, 8:56 am 
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Pelliott321 wrote:
A couple years ago I built a little SS phono preamp kit from DIYAUDIO that was designed to run on batteries. I was interested because I wanted to see the differences between 9 Volt batteries, SLA, and LiPo would sound like.
The 9 v batteries was horrible. The big SLA was a bit better and the LiPo was the best, probably because the internal resistance of the LiPo was the lowest.
The less than $100 board still was not very musical so I tried using a leftover shunt regulated PS from Twisted Pear that supplied mort than 10 times the required current and the sound was great.
In fact that phono preamp is living in a friends Uber system replacing a $6500 Ron Southerland phono and my friend could not be happier.

But....

My friend just cannot live with a cigar box phono preamp in his Uber-system so at his direction I am building for him an AN L3 phon preamp at almost $2k for him. Will see how this compares to the cigar box.

You mean that the cigar-box pre-amp isn't smokin' hot?! It might have been better if it was -- wait for it -- here it comes -- a Havana cigar box. :crazy:

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Pelliott321
PostPosted: April 7th, 2021, 9:07 am 
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I is a wooden cigar box with a natural lacquer finish and that added to sound.
I will never part with it.
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SoundMods
PostPosted: April 7th, 2021, 9:55 am 
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Pelliott321 wrote:
I is a wooden cigar box with a natural lacquer finish and that added to sound.
I will never part with it.

Some of those wood cigar boxes are much better than the cigars they contained. I used to be into cigars -- especially Havanas -- when I could get them.

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Pelliott321
PostPosted: April 7th, 2021, 10:05 am 
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to me, cigars always smelled better than they tasted

Talking about getting off topic
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