Hi
New to the forum
I'm in the process of trying to change caps in my pp amplifiers
The amps are very solid state sounding and i'm trying to empart a bit of musicality and body to the sound the stock caps are Sonicap gen 1 although balanced sounding they lack musicality I eventually switched these to the Russian k40's although musical I lost all of the transparency and dynamics the music seems rolled off
The next set of caps I want to try out is a mix hybrid sort of
I was thinking of going with Dynamicaps in the input positon and Jupiter in the Finals (the amps only have 3 coupling caps no cap goes to the output tube)
I want to somehow try to keep the transparency and good dynamics of the Gen 1 and add some midrange and frequency extension with the Jupiters
Any thoughts on this combo
I currently have vcap teflons in my pre amp and before I went with the Russian k40 the system was a bit too analytical and revealing
The k40 smoothed things out but at the expense of everthing else
Any input appreciated
New to the forum
I'm in the process of trying to change caps in my pp amplifiers
The amps are very solid state sounding and i'm trying to empart a bit of musicality and body to the sound the stock caps are Sonicap gen 1 although balanced sounding they lack musicality I eventually switched these to the Russian k40's although musical I lost all of the transparency and dynamics the music seems rolled off
The next set of caps I want to try out is a mix hybrid sort of
I was thinking of going with Dynamicaps in the input positon and Jupiter in the Finals (the amps only have 3 coupling caps no cap goes to the output tube)
I want to somehow try to keep the transparency and good dynamics of the Gen 1 and add some midrange and frequency extension with the Jupiters
Any thoughts on this combo
I currently have vcap teflons in my pre amp and before I went with the Russian k40 the system was a bit too analytical and revealing
The k40 smoothed things out but at the expense of everthing else
Any input appreciated
It shouldn't be too hard to trace out if you can't find a schematic. Good practice, too.
Most commercial tube amps can be greatly improved with a few extra parts or a tweaking of the values of parts already there.
That solid state sound is more likely being caused by too much gNFB. Reducing the gNFB, assuming that the reason for excessive gNFB in the first place was not an attempt to cover up a horrible open loop design (there is all too much of that going around) will do more for sonic improvement than supposedly magical audiophool capacitors (or any other gimmick).
I just know if too much gNFB will reduce sonic. I instead use as much gNFB but with "tube character" resistor like Allen Bradley in this position (feedback R and bypass R/divider), in order to get the tube sound through this gNFB. Am I doing wrong? I use 33k/10k (3.3 gain), while normal circuit implement 10 to 20 of gain.
Vacuum-suspended gold foil might sound even better ... at least to the person paying for it.
Do you have any source to back up the "not a good idea to use the same type of capacitors" notion ? Whatever it was, I'm pretty sure it was referring to capacity value rather than the type, which makes perfect sense, especially when coupling capacitors also serve as parts of HP filters (to prevent RF amplification and/or oscillation which could lead to unwanted distortion).
You are after the perfect capacitor in all positions. The closest to that is the polypropylene in my opinion, as it's a good solid slice of audio magic at a reasonable cost.
If you want fancy caps your best route is to try caps in parallel, with themselves or other types - i.e. poly and oil. These will always beat the money, and money usually gives you something that has to be 'run in' - uggh!
However once you have poly caps your next attack should be feedback loops. If you change the global negative feedback to a series of local ones (the output stage may also need to driver stage too, for the gain - but that is still only a 2 device loop). This also allows you to eliminated cathode bypass caps. With this you need to study tube operating points - you are looking for linearity here, intrinsic linearity, not a fudge you then mash up with global feedback.
My view is that simple distortion is less important than global feedback, as global feedback just moves it around, it does not get rid of it. You need to realise that global feedback is _too late_. For subwoofers this may be OK, for full range, it's a mess, as corrections of corrections swirl around and around.
The only place you may need more is the critical output+OPT stage to flatten some loudspeaker impedance spikes, the amount of which usually necessitates including the driver tube too, but if you can avoid this the better. As always, engineering is a compromise.
After that, some decent current sources to replace your anode resistors are the next step, but you may already be happy with the sound before then.
The trouble with Teflon caps is they tend to be large for a given value, expensive and may not be available in the value you need. Because of this there might be a tendency to use a smaller than needed value, messing up low frequency response. Second in line is polystyrene. They are about as perfect as a cap can be, but not terribly available in large sizes and can't handle high temperatures- not a good thing in a tube amp. Polypropylene is extremely close to polystyrene in specifications, but can handle high temperatures and doesn't cost too much. That's my choice almost everywhere unless I happen to find some NOS styrenes. As others have said, you need to learn schematics and trace out the amp. Blindly changing parts by brand name is an expensive and never ending fools game. There's also the issue of whether good (stable, low D) capacitors, if they really change the sound, change it in a way you find pleasing. People seem to take that as a given, but the more I learn, the more I question it. Technical perfection in engineering terms may not equate to ultimate sonic goodness.
CH
CH
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.