200S recap

[Soundmasterg]

i've never had a problem with the 525V multi's or the 600V spragues. and by the time the multicap sees the voltage that it is filtering it is no where near 560V (the highest being 500V) and all of my Sunns work perfect with them whether they're tube or SS rectified.

2 cents........

I suppose it depends on the amp. The 2000S's that I've seen are around 500V B+, but the 200S's, Sonic 1's, etc that I've seen are from 535v to 560v, and with these, the 3rd cap is still seeing 500v, and the first couple are over the 525v level. My personal 1970 Sonic 1 is 560v B+. I am sure if you call AES and ask their reps if they certify their can caps to anywhere above 525v they will not want you to use them at those levels. If your amps are below the 525v when the caps see that level, then you're probably ok, but I wouldn't say everyone is just because your amps are fine. Every amp is different, and the 2x6550/KT88 Sunns that I've seen all have too high of a B+ for those can caps.

The Spragues are expensive and are outperformed in ESR and several other specs by modern caps. Sprague says to not use the Atoms in modern designs and that they are for vintage replacement purposes only. Obviously they will work fine in the Sunns, but why pay so much money when you can get a superior product elsewhere. I am sure Conrad would have used b etter caps if they were available then. He certainly uses better caps nowadays. If you don't believe me, then ask him.

Alot of people like higher cap values (i.e. 50uf instead of 20uf), but i am not only a tradionalist but also somewhat of a purist when it comes to my amp restorations (so i always strive to use OEM and NOS  parts with stock sizes and values).  I also prefer the stock filtering's compression and low end (less stiff sounding to me) but YMMV. 

I don't think you would notice a huge difference in the feel of the bass going from 20uf to 50uf, but you can still use the tube rectifier if you like at that level. I prefer going up to 110uf (using two series connected 200uf 350v caps) for the first filter stage, and you do notice a difference there. It still isn't as stiff as solid state with this setup. It is important to not change the values for the preamp filter caps though since that will change the tone for the worse. If these Sunns were worth what some of the old Fenders were, then it might be different, but they will never be worth more than many of the old Fenders, Marshalls, Voxes, etc. They are climbing in value, sure, but they won't outperform those other brands in the price wars. If the cap mods are done right, then no holes or very few holes have to be drilled to mount the caps. It can be taken back to stock easily, though many players like the modded amps better. If they own the amp and want to mod it, then that is their choice, just as it is yours to use OEM and NOS parts to keep it stock. In some cases though, like grillecloth for example, the old parts are not available anymore so you are stuck with some other method to restore them. As time goes on, Sprague Atoms will probably go away along with many other parts, and then you will have to make some choices. When I started the discrete cap mod, using larger cap values, the cans were unavailable, and since it sounded so good, I've stuck with it if others like it and request it. Now the caps are available again but are more expensive than the method I use. The coupling caps that were used in the Sunns originally were not very good, and were the same as the "brown turd" or "chocolate drop" caps that were used in the Silverface Fenders and got a bad reputation. They are not very good quality caps and have high ESR. Many of the other brands of caps used like the green Cornell-Dubliers were also poor quality and nowadays more often than not will leak DC. So do you prefer to keep an amp that is all original but not working right, or do you hunt down a NOS cap, or do you replace with a modern equivilant that will perform better and sound as good or better?

Greg

[johnk]

i have absolutely no desire to try to make an amp that sounds awesome in it original configuration sound different or questionably better. after repairing/restoring amps for more than 35 years, i have seen alot of hack jobs and modifications done to vintage amps and their original owners telling me that their amps never sounded the same after a previous tech had repaired them (and changed the values calling it an "upgrade".) everytime that i worked on one of those amps i removed the mods and put in USA caps with the stock values and their owners were extremely pleased with the results. if the stock 525V multicaps couldn't handle the B+ voltage, it surprises me that the old Sunns could run 30-40 years with the originals before needed to recap them.

[Soundmasterg]

I would say to not knock the sound of a modded one unless you've played and heard it yourself, but I realize that everyone hears differently, so it is open to interpretation. I've seen hack jobs as you mention and I never do anything like those. If I mod an amp for someone, I do so when they request it, and with an eye on keeping it to where it can be easily restored back to stock if wanted. If carefully done, mods as I suggested can be done without drilling new holes. Since you have a lot of experience repairing amps, you know as well as I that often just changing the old parts for new when replacements are necessary will cause the sound to change. Some amps such as some Silverface Fenders have errors in them that need to be fixed in order to function correctly such as too long grid wires on the phase inverter for instance. The Sunns have their errors too, though not as obvious as that particular one. I'd guess that Conrad is like what many thought Leo Fender was like in that if better parts were available for cheaper back in the day, he would have used them. You'll notice in his modern line of Conrad amps that he makes, he doesn't use Sprague atoms or can caps. The amps sound great too btw.

The fact that you mentioned USA caps as you did sounds like you are disparaging foreign caps? Been listening to Gerald Weber too much perhaps? Many foreign caps (F & T, Xicon, Rubicon, Nichicon) will test out to better performance than the Sprague Atoms and are smaller so they fit into many applications better. They're also vastly cheaper than the Atoms. I'm not talking about sound tests or anything like that. I'm talking to ESR specs, leakage specs, etc....things that can actually be measured. Sprague makes other, more modern caps that perform better and are cheaper than the Atoms too btw. I'd make a guess that the line voltage was lower when those amps were new and for awhile afterwards, so the voltages were closer to the caps ratings than they are today. If the amps got continuous use then the caps last quite a long time. If they didn't then the caps fail. If they're consistantly over-voltage on the caps, then the caps have more heat to deal with and their life will be shorter. Thats physics. Now if the caps still last 35 years after that, then they're good caps. When AES first came out with those new ones, they had issues though and lots of failures for around 6 months. That was one of the reasons I didn't use them, and the other was cost. There hasn't been enough time passed yet with the new AES cans to see how long they will last and if they will match the old caps for longevity.

What will you do if/when Sprague discontinues their Atom line or AES stops making those can caps? Or if the green Cornell/Dublier caps start leaking DC and cause a stage to oscillate? Try to hunt down NOS ones or replace with modern equivilants?

Just wondering.

Greg

[johnk]

Hi Greg,
i have purchased a few used Sunns with various aftermarket caps installed in them, including one of them with the "cap board". every one of them didn't sound right to me, so i replaced them with the Spragues and the reissue cans and afterwards they sounded like what i expected them to sound like, and they sound almost exactly like the ones that i didn't have to replace caps in.

i'm sure that you are aware that no two amps sound alike-especially vintage ones. i had three 100% stock 190B's and while all of them sounded very similar, the gain on all of them was drastically different. after recapping all but one of them, they still had the same diferences, and this was after using the same set of vintage NOS tubes in all of them (swapping them from amp to amp). since they all sounded great afterwards, i saw no reason to investigate them further (i.e. changing coupling caps or more resistors) as i prefer to leave a good running amp as original as possible. besides, the tranny voltages can vary quite abit on them as well.

i worked with Leo Fender back in the late 70's and i once asked him about how CBS basically ruined the blackfaced amp line and he replied "John, every musician has a bit of distortion in their life, so i saw no reason to change or improve them" which made me laugh. he told me that there were some new CBS engineers from cal-tech that thought the amps had some "potential" so they redesigned them to have more clean power, and to me, that's when things started going downhill.

i don't like the sound of Xicon or Nichicon caps and my good friend Brian Gerhard (of Top Hat Amps) doesn't either. We experimented extensively with every brand of new cap available in his amps and found the Sprague Atoms are the most suited to our taste.

The line voltage on the old original Sunn and Fender schematics states it to be 117V which isn't much different than it is today (maybe 120V?), so i don't really see that as a problem.

being in the business so long, i still have alot of NOS caps that i can replace the originals with, if i can't find the exact value in a coupling cap, i usually use a new Mallory 150 series as i think they sound great. I have been using Sprague Atoms in old Fender restorations since 1980 and have not had a single failure on one of them yet, so i'm not all that concerned about it.

And no, i disagree with almost everything that Gerald Weber says. It seems that his opinion of tone, and my opinion are 180 degrees apart. I have yet to hear a Kendrick amp that sounds good, let alone great. he voices them way to harsh and midrangey for my taste.\

everyone is entitled to their opinion and the way that they want their amp to sound, i'm just so stuck in my ways that i like them to sound as original as possible, whether they used better spec'd parts or not. i love the amps the way that the were and rarely hear a new amp that has the character and vibe of the old ones.

[Soundmasterg]

Hi John,

It seems like you only like the vintage Sunn sound, and thats valid for you. Some people don't want the sag for bass, and want a bit tighter bass response, but still want to use the Sunns, and this is a solution for them. If done with a cap board and/or discrete caps without drilling holes, then it is reversible and easy to change back. It is cheaper too.

Yeah, no two amps sound alike, and I'm sure you'll agree that even the same amp sounds different from day to day sometimes! The line voltage in my area is often 125v and sometimes as high as 130v. I rarely see it below 122v here. That affects the B+ of course, and not linearly either. I've noticed that the earlier Sunns up to around 1967 or so often have a lower B+ than the later ones, and I suspect that it occured when they switched from Dynaco to Thoradson or Schumacher transformers or whoever it was they switched to.

I overhauled a friend's 2000S and used some 600v Sprague Atoms in it that I had on hand that were maybe 7 years old and new. Just in case I reformed them. Two of them failed after less than 2 months in use. I've never had that happen with a Xicon though I've seen issues with Illinois caps. I prefer F & T but they don't come in all values. The Webervst caps are pretty good too so far. Personally I notice much more difference experimenting with coupling caps rather than electrolytic filter caps, but YMMV. Thats assuming the value was the kept same of course. I too like the M150's a lot and use them in many amps along with Orange Drop (716P and 225P) and Sozo. I've used Solen also, though I think they are better suited for hi-fi myself. I've used some NOS coupling caps, but I check them for leakage first. I won't use NOS electrolytics however.

I've heard quite a few new amps that sound as good or better than the old ones. There's quite a few of the old ones that are just dogs and don't sound very good no matter what you do to them too. For reissues most of the old ones sound better though the original Korg reissue AC30's that were made in the Marshall factory (1993 to 2004) sound very good. I'm impressed with the Victoria Regal II, the Conrad Blues Jammer, and Rocket Vessel, (check out his site for sound clips) and some of the Dr. Z stuff among others. Of course these are all guitar amps...there isn't much these days for tube bass amps. I've also heard some really good things about the Reeves amps that are clones of the old Hiwatts, but don't have the cash to get one so I can't hear one.

Greg

[johnk]

wow! i have never seen my line voltage go over 121V! (in southern california)

and yeah, i only use new spragues, not NOS ones (unless they're only a year or two old in which case i also re-form them on a variac).

i do like Victoria amps, and my buddy Brian's Top Hats are nice too.

I have an old (69/70) Ampeg SVT blue line that i need to tune up so I thought that i'd take a chance and  bought a brand new SVT-VR reissue last november. I have to say, after personally owning nine SVT's over my 41 years of playing bass (and servicing about 100 of them), surprisingly, their new VR is a great amp and basically sounds like what i expect a vintage SVT to sound (and feel) like. it appears to be built well (although it has different physical layout with staggered output tubes). so IMO, a good or great amp doesn't have to be vintage for me to like it.

I also have a '74 Sound City bass 150 and its an awesome sounding amp after i recapped it and retubed it. its point to point with huge tranformers. here's some pics of it:

[EdBass]

That Sound City is a very nice amp, very Hiwattish for obvious reasons.
In my youth British = Marshall, anything else was second rate; in my circles in the 70's we called them "Sound Sh*tty's", but mostly because we thought it was clever more than because of issues with the amps themselves. I didn't really get into the Dave Reeves thing until the 90's, now I'm an afficianado. Those early 70's Reeves circuits are outstanding for bass, tons of headroom, real chimey and rock solid on the bottom but still maintaining that excellent tube tone.
I've already booked my rooms for the Hiwatt convention June 27-29, Glynn Reeves is flying in from England, and there will also be incredibly rare vintage Hiwatt bass cabinets in attendance, it should be a blast!
Anyway, this is a Sunn site...
The high startup voltage issue stems from the old Dynaco Mk III's, which are known for filter cap issues since the advent of higher AC line voltages. Since the Sunns are heavily based on the Dynaco circuits, it seems to be a natural progression that higher voltage caps would be in order.
On the other hand, I also have a '67 200S with original everything (including Genelex KT88's) that still sounds great; no leakage, just a little noisy, nothing too severe to play out with. However, the majority of my old Sunn gear needed caps right away. No suprise there, I figure 30 years on any electrolytic is plenty.
I like the sound of my SDS board amps, very little tonal difference but that "secure" feeling having been exposed to the Mark II & III cap issues first hand. You can switch between plug in SS and tube rectifiers, and most importantly you can reverse the surgery easily.

This whole discussion is going to force me to get some of those German can caps though! 

[johnk]

Hi Ed,
yeah, we used to call them sound sh*tties too, so i guess that was the way of referring to them back then.

[Soundmasterg]

Mmmmm, theres nothing like looking at the insides of a Hiwatt/Sound City. Those things are made very nicely and sound even better.

wow! i have never seen my line voltage go over 121V! (in southern california)

Maybe thats because there are so many people down there using the line?

I've got an SVT also, though mine is a 1981 MTI-made one with US transformers. The very early ones of these had surplus US transformers with Japanese parts so with some parts replacements they sound just like the Magnavox era ones. Mine had a factory miswire that shunted all the signal for channel 1 through a .022uf cap instead of a .22uf, so obviously the bass was lacking for 25 years on it! I need to go through it though as some caps are getting old and it's begun to make noises here and there.

Ed, where is the Hiwatt convention at?

The advantage of those SDS boards over the caps I've used is that you can still use a tube rectifier if you want. I liked it better with the Weber Copper Cap and the higher value caps myself. Personally I think the '67 and earlier 200S's sound better than the later ones like mine. The voltages are a bit lower and they're browner sounding. I plan to tweak with mine to reduce the preamp voltages a little and see if that gets me closer to some of the older Sunns when I get some free time.

Greg

[johnk]

Hi Greg,
yeah, i had a 1966 Sonic II which was pretty much the same circuit as a 200S and it was very smooth sounding (a little more brownish). It had the gray Dynaco trannies in it. i actually liked the way that it looked too, with the older grill cloth, numbered panel with the knobs that had just a white pointer on them and the Sunn logo didn't have the "r" yet. I sometimes used it with a Weber copper cap, but my favorites are the SS rectified 190Bs now. their response seems a little bit faster and punchier to me.

johnk

[EdBass]

Ed, where is the Hiwatt convention at?

Not too far from Indianapolis in Columbus, IN.
http://www.vintagehiwattconvention.com/

[Isaac]

That Sound City is a very nice amp, very Hiwattish for obvious reasons.
In my youth British = Marshall, anything else was second rate; in my circles in the 70's we called them "Sound Sh*tty's"...

Hi Ed,
yeah, we used to call them sound sh*tties too, so i guess that was the way of referring to them back then.

So did we, but we called them that because the Sound City amps our guitarists had really did sound sh*tty.

[johnk]

So did we, but we called them that because the Sound City amps our guitarists had really did sound sh*tty.

 

[Soundmasterg]

I sometimes used it with a Weber copper cap, but my favorites are the SS rectified 190Bs now. their response seems a little bit faster and punchier to me.

Thats kind of what the cap mod does too. Tighter and quicker bass mostly, though you have to use a SS rectifier with the mod, and so part of it is that too.

Not too far from Indianapolis in Columbus, IN.

Darn...was hoping it was somewhere out west.

Greg