amp parts in UK? (sozo capacitors, metal film resistors, tubes)

[ericsabbath]

Hey guys.

I'm looking for some specific parts to mod my Framus Cobra.
I was planning to buy from USA, but the US dollar gone wild and I got some british pounds in my paypal account.
Is there any good UK online shop with worldwide shipping?

Thanks.

[hamfist]

Metroamp are the only supplier of Sozo caps, I think. I use Mallory 150's, which are very popular in Marshall-type circuits. I get them from Hotrox (http://www.hotroxuk.com/store/erol.html#6136X0), or Tube-Town (http://www.tube-town.net/ttstore/index.php/cat/c34_Mallory.html). 
  tube town also supply all the Metal film resistors you could need, but I use Carbon Film resistors from Jabdog (http://www.jabdog.com/res-car.htm). I'm no expert, but the general concensus seems to be that carbon films provide pretty much the best compromise between clarity, low-noise and warmth in a resistor.
  TAD also do there own range of caps (http://www.tubeampdoctor.com/index.php?cPath=35_109), but I don't know who actually manufacturs them. I have used them though, and they are fine.

Allparts (http://www.allparts.uk.com/Allparts-home-c-276.html) do a good range of Mallory and Dijon caps.

Rapidonline  (http://www.rapidonline.com/products.aspx?tier1=Electronic+Components&tier2=Resistors+%26+Potentiometer) also do a vast range of Metal film and Carbon film resistors.

  Current production tubes, I get from Hotrox or Watford Valves, depending on who's got what in stock. Hotrox are usually slightly cheaper.

[HTH AMPS]

I mainly use Vishay/ERO (Roederstein MKT) caps, they are cheap and sound great.  I get them from Farnell here in the UK available in 400v and 630v options...

http://uk.farnell.com/1413830/passives/product.us0?sku=vishay-mkt1813310405
http://uk.farnell.com/1413835/passives/product.us0?sku=vishay-mkt1813310635

The Sozos caps can be ordered direct through Sozo (the only way I've ever ordered them) and I can vouch that they do sound very nice.  'That' much better than EROs? - I wouldn't say so.

[hamfist]

Interesting link HTH.

I'm not familiar with that range. There seems to be a very minimal range at 630V, but many more rated at 400V. Isn't 400V a little bit close for comfort to the danger zone ?

I see they also do a large range in 1000V and 2000V ratings. I've not heard of anyone using such high rated caps in a tube amp before. Have you used those before as well, or do you stick with the 400V and 630V's

[HTH AMPS]

Interesting link HTH.

I'm not familiar with that range. There seems to be a very minimal range at 630V, but many more rated at 400V. Isn't 400V a little bit close for comfort to the danger zone ?

I see they also do a large range in 1000V and 2000V ratings. I've not heard of anyone using such high rated caps in a tube amp before. Have you used those before as well, or do you stick with the 400V and 630V's

I don't think 400v is too close for comfort - theres very few places in an amp where a cap (in the signal path) will see above 400v, maybe 320v at the most on the PI plates.  The smoothing caps otoh will see much higher voltages in the 450v+ region, but are rated accordingly. If the voltage rating is too low, it's commonplace to wire the caps in series to increase the voltage rating.

[hamfist]

Interesting link HTH.

I'm not familiar with that range. There seems to be a very minimal range at 630V, but many more rated at 400V. Isn't 400V a little bit close for comfort to the danger zone ?

I see they also do a large range in 1000V and 2000V ratings. I've not heard of anyone using such high rated caps in a tube amp before. Have you used those before as well, or do you stick with the 400V and 630V's

I don't think 400v is too close for comfort - theres very few places in an amp where a cap (in the signal path) will see above 400v, maybe 320v at the most on the PI plates.  The smoothing caps otoh will see much higher voltages in the 450v+ region, but are rated accordingly. If the voltage rating is too low, it's commonplace to wire the caps in series to increase the voltage rating.

Thanks HTH, I might give them a go next time I buy some caps.  Although at my current rate of usage I probably have a few years supply already, as I'm only tweaking.   WHen I finally get around to building I'll definately be needing some more.

[ericsabbath]

thanks, guys

I'm looking for caps with the smooth mids of the sozos, as I'm trying to smooth my amp (that's very dry and aggressive)

[hamfist]

thanks, guys

I'm looking for caps with the smooth mids of the sozos, as I'm trying to smooth my amp (that's very dry and aggressive)

Mallory 150's would certainly be good for what you are looking for.

[jpfamps]

400 V caps are OK under working conditions, however if you have an amp with a SS rectifier and no standby switch, or you forget to use the standby switch (no of course not YOU, never) you will impose the full B+ onto all your coupling caps. In the PI of a fixed bias amp the situation is made worse because the other end of the coupling cap from the plates will be at the negative bias voltage.

So in a typical 40-50W amp you might have a B+ of 450 and a bias of say -40 V, so you potentially could have 490 V across your coupling caps in the PI under such circumstances.

I try to plan for the worst case scenario, and so use 630 V polyester caps (Vishay/ERO or Mallory) with good results.

There is no disadvantage to using a plastic cap with a higher voltage rating than necessary other than cost and size.

 

[hamfist]

400 V caps are OK under working conditions, however if you have an amp with a SS rectifier and no standby switch, or you forget to use the standby switch (no of course not YOU, never) you will impose the full B+ onto all your coupling caps. In the PI of a fixed bias amp the situation is made worse because the other end of the coupling cap from the plates will be at the negative bias voltage.

So in a typical 40-50W amp you might have a B+ of 450 and a bias of say -40 V, so you potentially could have 490 V across your coupling caps in the PI under such circumstances.

I try to plan for the worst case scenario, and so use 630 V polyester caps (Vishay/ERO or Mallory) with good results.

There is no disadvantage to using a plastic cap with a higher voltage rating than necessary other than cost and size.

Thanks JPF, that's good info.   I've noticed that I've got 400V Mustards in my Wilsic Sound V-50, but that amp (2 x EL34) is tube rectified (B+ of about 440V).
  Could you explain how a tube rectifier would stop the full B+ hitting the coupling caps on start up, wheras a SS rectifier would not (in the scenario of no standby switch (or even a "forgotten" standby switch)).
  Is there some sort of surge of available voltage on start up, which subsides whe the tubes warm up ?  I'd love to understand.

[jpfamps]

All valves require the filament to reach an appropriate temperature before they conduct any current (hint they are not called thermionic valves for nothing!). This takes a minute or so. When you turn on an amp with a valve rectifier it won't start conducting current until the filament in the rectifier has warmed up, and so the voltage applied to the amp will rise gradually. This is often referred to a "soft start", and means that a standby switch is less of an issue in this style of amp.

OK in an amp with a SS rectifier the full B+ (actually this will probably be higher than the B+ when the amp is running as power supply is unloaded) is applied as soon as the amp is switched on (assuming no standby switch). As none of the valves in the amp are conducting (as their filaments need to warm up), no voltage will be dropped across the plate load resistors (ohms law again) and the full B+ will be imposed on the plates of all the preamp valves. The PI coupling caps can thus have the full B+ on one end and the negative grid bias on the other making the situation worse.

My guess is that a 400 V cap in a 50W amp with say 450 V B+ will probably withstand some abuse and you will get away with this in most circumstances, however the long-term reliability could probably be compromised. Reliability 10 years down the line isn't on the radar for most manufacturers.

If you are building your own amp from scratch the extra cost of 630V caps vs 400V caps is marginal (unless you want to go for some exotic audiophile caps), so I recommend using caps rated for the difference between the B+ and the grid bias in the PI, and rated for the B+ in the pre-amp.

So for an AC30 say 400 V caps will be fine, but in a Marshall alipanel Super Lead I would go for the 630 V.

Another issue with valve rectifiers is that they drop quite a number of volts, which is why you should exercise caution if you swap a valve rectifier for a solid state rectifier. I'm currently sorting out an AC30 that someone has put a mains transformer from a 50W amp into AND replaced the valve rectifier with SS diodes. The B+ rose to 480 before I turned the amp off asap!! Notwithstanding the effects on the EL84 output valves which are rated at 300 V maximum, none of the caps in the amp are rated for this voltage. Incidentally the guy who owns this amp has been using it for several years without problems other than the fact it didn't sound great. Not surprising given the state of the electronics and the speakers were shot and wired out of phase.............

[hamfist]

All valves require the filament to reach an appropriate temperature before they conduct any current (hint they are not called thermionic valves for nothing!). This takes a minute or so. When you turn on an amp with a valve rectifier it won't start conducting current until the filament in the rectifier has warmed up, and so the voltage applied to the amp will rise gradually. This is often referred to a "soft start", and means that a standby switch is less of an issue in this style of amp.

OK in an amp with a SS rectifier the full B+ (actually this will probably be higher than the B+ when the amp is running as power supply is unloaded) is applied as soon as the amp is switched on (assuming no standby switch). As none of the valves in the amp are conducting (as their filaments need to warm up), no voltage will be dropped across the plate load resistors (ohms law again) and the full B+ will be imposed on the plates of all the preamp valves. The PI coupling caps can thus have the full B+ on one end and the negative grid bias on the other making the situation worse.

My guess is that a 400 V cap in a 50W amp with say 450 V B+ will probably withstand some abuse and you will get away with this in most circumstances, however the long-term reliability could probably be compromised. Reliability 10 years down the line isn't on the radar for most manufacturers.

If you are building your own amp from scratch the extra cost of 630V caps vs 400V caps is marginal (unless you want to go for some exotic audiophile caps), so I recommend using caps rated for the difference between the B+ and the grid bias in the PI, and rated for the B+ in the pre-amp.

So for an AC30 say 400 V caps will be fine, but in a Marshall alipanel Super Lead I would go for the 630 V.

Another issue with valve rectifiers is that they drop quite a number of volts, which is why you should exercise caution if you swap a valve rectifier for a solid state rectifier. I'm currently sorting out an AC30 that someone has put a mains transformer from a 50W amp into AND replaced the valve rectifier with SS diodes. The B+ rose to 480 before I turned the amp off asap!! Notwithstanding the effects on the EL84 output valves which are rated at 300 V maximum, none of the caps in the amp are rated for this voltage. Incidentally the guy who owns this amp has been using it for several years without problems other than the fact it didn't sound great. Not surprising given the state of the electronics and the speakers were shot and wired out of phase.............

Thanks JPF.  Love having you around !!

[ericsabbath]

thanks, guys

I'm looking for caps with the smooth mids of the sozos, as I'm trying to smooth my amp (that's very dry and aggressive)

Mallory 150's would certainly be good for what you are looking for.

I've heard that the vishay roedersteins are close to the mallories
those are nice but they don't have the mids of the sozo :(

http://forum.metroamp.com/download/file.php?id=1968 (handwired Marshall with stock roedersteins)
http://forum.metroamp.com/download/file.php?id=1971 (same same after sozos)

[hamfist]

thanks, guys

I'm looking for caps with the smooth mids of the sozos, as I'm trying to smooth my amp (that's very dry and aggressive)

Mallory 150's would certainly be good for what you are looking for.

I've heard that the vishay roedersteins are close to the mallories
those are nice but they don't have the mids of the sozo :(

http://forum.metroamp.com/download/file.php?id=1968 (handwired Marshall with stock roedersteins)
http://forum.metroamp.com/download/file.php?id=1971 (same same after sozos)

There have been a lot opinions given over the www about whether different brands of essentially the same value and construction capacitor actually do give a different tone. I am not convinced that anyone has done a truly accurate comparative test. Even Sozos are manufactured at +/- 5% so to accurately compare one brand of caps with another, every cap must be tested and matched with the one it is replacing. From what I've seen no-one has actually done that.
   There certainly is minimal difference between the two clips you link to. The 2nd may have a tiny bit of something extra going on in the mids, but nothing that a little turn of the mids pot would not rectify.

  At soon as you start playing with other musicians, I don't think you would hear any difference between Vishays, Mallories, or Sozos. Far more differences can be got by actually tweaking cap and resistor values in the pre-amp.
  However, if you have your heart set on Sozos then I'd go for it. You will not feel satisfied until you've got them, and you will always be wondering whether your amp might have been a tiny bit better if you had only gone with the Sozos.
  I am convinced that a lot of the perceived differences are down to psyco-acoustics.

[ericsabbath]

I ended buying a bunch red WIMA caps from Banzai Effects (germany)
WIMA MKP (metallized polypropylene) for coupling and phase inverter input and outputs, WIMA MKS (metallized polyester) for the cathode bypasses, WIMA FKP (polypropylene) for the plates and some other points

I decided for these cause they will fit the leg spacings on the board better, they were very cheap and I believe these are good ones too (used a lot by Bogner and Diezel)
I know they sound nothing like the Sozos but I was afraid that the Sozos could make it too smooth and they would cost like 10x more

thanks, guys!