What you have to realise is that the metal case on a lot of electrolytic capacitors is also connected to the negative tag of the capacitor. So removing the plastic cover off the capacitor is a big "No No", as you will then be connecting the negative rail of the HT, which is also the audio ground to the chassis via the fixing clamp. This is really asking for trouble when using the ST20 in a modern system.
chiily
PFM Special Builder
That's some good advice. I always check whether the cap's metal can is connected to the -ive of the cap. Likewise there are some vintage cap installations where it relies on the cap's can being connected top the -ive tab, I think the 8uF one in AVO CT160s work like this and I'm sure the one in Quad FM1s are the same.
les24preludes
pfm Member
Not that I'm aware of. You mean the mains transformer presumably, not the output transformers. You'll just get less volume than with efficient speakers. The operating points of the valves remain the same.
Radford Revival
Trade: Radford Revival
If you're needing more output from an amp then strictly speaking, yes, if you're driving the amplifier out of its Class-A region, the load on the amplifier will increase and the mains transformer will get hotter.
Some amplifiers can't leave Class-A, like single ended amplifiers, and very occasionally push pull amps that are deliberately designed in a certain way. If the load is properly matched then the mains transformer load will remain approximately constant.
An amp like a Stereo 20 or for that matter most amps will likely audibly complain before you run the risk of damaging anything, in practise you have to be pushing things fairly hard for this to be an actual problem in reality.
Simple amps like the Stereo 20 are cathode biased, which will tend to bias themselves cooler the more power you try to get out of them. If you ever drive one to continuous sinewave clipping you see crossover distortion appear very rapidly.
les24preludes
pfm Member
Thanks for that. I only ever use SE amps in Class A, so I wasn't aware of any change. Class AB evidently goes into different territory.
Radford Revival
Trade: Radford Revival
Quite literally - The loadline on the Class-AB amp goes off the conventional loadline plot, you have to extend it to negative current!
Sorry, yes I meant the mains transformer.
Mike P
Trade: Pickwell Audio
Tony L
Administrator
If using a passive preamp there is a strong argument for keeping low capacitance cables both sides of the attenuator. That said the Leak is very sensitive and high impedance so incredibly easy to deal with. I’m just using some Gotham GAC with my TL12 Plus that I soldered to an octal plug and its fine. I used vdH D102 with the Stereo 20, which is very low capacitance and a nice shade of yellow.
PS I’m not a believer in cheap cables as second hand audiophile cables are effectively free. They just cost an investment that can be released later by selling. I used to make my own from studio instrument cables, but the penny eventually dropped that was a more expensive ways of doing things! May as well buy a used vdH or whatever for £30-40 that will never not be worth £30-40.
PS I’m not a believer in cheap cables as second hand audiophile cables are effectively free. They just cost an investment that can be released later by selling. I used to make my own from studio instrument cables, but the penny eventually dropped that was a more expensive ways of doing things! May as well buy a used vdH or whatever for £30-40 that will never not be worth £30-40.
Years ago I made a batch of pairs of interconnect cables of different lengths from a roll of instrument cable. These have served me very well and I've never had a desire to try anything else. Length from DAC to Allegri is 45cm, and from Allegri to ST20 75cm.
Notwithstanding, I do 'get' Tony's view on audiophile cables being an investment that can be released at some point for little overall cost.
Notwithstanding, I do 'get' Tony's view on audiophile cables being an investment that can be released at some point for little overall cost.
Not all cables are Foo. Cables are very important in a good Hi-Fi system, especially a High-end system. You just have to decide what your budget is for cables and buy the best you can for your budget. Most of the mega expensive cables are made for certain markets where the cost of something is more important than what it does or how it performs. It sounds very strange, but we live in a strange world.
steveinspain
pfm Member
A question for all you Stereo 20 owners.
What are they like to live with ?
I am keen to hear just how good they are and how much one will add to the sounds I get from my 15" hpd's, but given my total lack of knowledge of all things electrical is a good recently overhauled one a plug and play thing - I don't mind replacing a valve or two every now and then, but will this mean messing with bias settings (whatever they are)
Are they costly to run, ie in terms of electricity bills, as I play music often for 10-15 hours a day?
It'll obviously be difficult to hear one in my system before buying but I guess if I can get one from one of the well known folks on here then it won't be hard to sell on at little cost - finally, if you happen to have one you are looking to sell soon then please let me know!
What are they like to live with ?
I am keen to hear just how good they are and how much one will add to the sounds I get from my 15" hpd's, but given my total lack of knowledge of all things electrical is a good recently overhauled one a plug and play thing - I don't mind replacing a valve or two every now and then, but will this mean messing with bias settings (whatever they are)
Are they costly to run, ie in terms of electricity bills, as I play music often for 10-15 hours a day?
It'll obviously be difficult to hear one in my system before buying but I guess if I can get one from one of the well known folks on here then it won't be hard to sell on at little cost - finally, if you happen to have one you are looking to sell soon then please let me know!
Alex S
carbon based lifeform
It's very easy to live with - no biasing to be done and well chosen cheaper valves can work well. Nonetheless, I did suffer ground loop issues and it's still not dead quiet, certainly liveable with though.
Having said that, it has turned out to be far the most expensive amp I've had since, to save the Mullards I treated it to and valves generally (I also listen 10-15hrs a day), I ended up purchasing an entire second system.
Having said that, it has turned out to be far the most expensive amp I've had since, to save the Mullards I treated it to and valves generally (I also listen 10-15hrs a day), I ended up purchasing an entire second system.
steveinspain
pfm Member
Ha, a second system with a second St 20....?
Thanks for that Alex, very reassuring.
Alex S
carbon based lifeform
A Technics SL-G700 player/streamer and Genelec 8331As - So at least 5 ST20s worth. It started as a pair of Audioengine A2s I had in a cupboard and escalated from there. So my best advice is, accept you'll need to replace the valves every year or so.
I'm very glad to have both systems and couldn't live without either now. As for which I prefer, probably the Leak with bigger, more efficient speakers but it's a tough call and, surprisingly, they sound more alike than different.