One really good thing about Express hiss

[rooster]

OK, I'm serious here, but it strikes me as funny, too. The Sozo caps need like 100 hours of burn in time to sound 'good', they say. So I bought some mustard types and installed them. Hm. Then I played the Express for a bit and I thought the amp did sound somewhat edgy. At least edgier than with the Allyn PVC Mallory. (And here I am talking specifically about the .1 coupler cap that goes to the PI, as I already run a .002 Sozo in the earlier V2 stage, and it has 100 hours on it already.)

Anyway, I thought about it, considered the 'hiss factor' and then decided to just turn the amp on, turn all the controls to 3/4 on, and just let it run for 5 hours. Now, when you think about it, that's probably giving the cap a lot more audio information than I would normally give it when I play - and probably a much broader spectrum of sound. I mean, isn't this almost white noise? So I just play tested it and - wow - I think my 100 hour burn in process has probably been met. And just to be safe, I'm gonna do this for a few more days, 5 hour increments.

So, here's to the hiss! I think you can use it to your advantage given the need.

[Bob S]

Thanks for the post Rooster. I've built a Liverpool clone that hisses like a bitch. I've been putting off fixing it cos it sounds awesome. Just got my Rocket build up & running, so I was gonna start trying to fix the Pool hiss. I think I'll let the caps cook first - sounds like a good idea . 100 hours playing would take months for me.

[jaybeemusic]

First off, hello everyone this is my first post. Long time member/lurker but i'm a luthier, not an electronics expert so i've never had anything to say before.

here goes,

as far as the hiss goes, wouldn't it matter WHERE in the signal chain the noise is generated? If it was generated after the caps, they wouldn't see the noise and it wouldn't do anything.

just wondering

Jacques

[rooster]

Welcome, and yes, you are correct. As to where the hiss is generated, one can go about pulling tubes to discover where it is originating. In the Express, if you pull V2 - leaving only the PI (V3) going to the power tubes - you will find the Express quiet as a mouse, provided you have some decent power tubes, of course.

Which means the hiss is prior to the PI. Further, while the PI coupling cap itself may be generating some hiss, leave all tubes in and pull V1. If you have a working clone, you will have your answer.

The only question I have at this point is what is the resultant effect of running white noise through a circuit to break in the coupling caps, vs. a gtr signal? As I understand things, the 'path' through the cap is established by the signal, whatever it is, and over time it (the path) becomes more easily traveled, producing - somehow - a warmer sound in the resultant 'ease' of travel through the cap. ....So does using the white noise the Express generates create a broader path than a gtr signal? Or does the cap not care? Ah, science.

After 15 hours of 'hiss 'burn in, I can easily report that my Express has never sounded better. IMO, there is a clarity to the Sozo cap that is just not in the PVC Mallory cap, or the other caps I have tried, for that matter. It seems to be all about the 'singing' factor here, the voice is just more striking, more, well, 'striking' is the word. And I hate writing stuff like this because its subjective and really undefinable. That said, I definitely think the Sozo cap is worth trying in the Express, and I think the 'hiss method' of break in is definitely worth trying, too. ....And all of this said, with the amp sounding so good right now, I can see that putting 100 hours on it with my gtr could be maybe one of the best experiences of my life. Again, thank you Ken Fischer!! This is a truly great great circuit.

[WhopperPlate]

Very interesting Rooster, I've been contemplating vintage Sozo's in my xpress as well and you're giving me some fuel for my fire.

I've got a good amount of playing hours on the Express and have I left the amp on overnight several times. I have clarity and touch response out the ying yang, but I'm still missing a certain chewy vocal quality that I have found with my vintage Sozo equipped amps.

Tell me Rooster, which spots in the amp have you installed the sozos / mustards?

Thanks!

[rooster]

Charlie - Sure. I have the .002 off V2 that I have run for a few years. (Edit: Doh, wait a minute, make that 1 year now.) The one that I'm talking about here is the PI coupling cap, the .1 that begins V3. FWIW, I did also replace the current coupling cap that sits between the presence pot 10K tail and the 1 meg resistor of the PI, too, but it is not an audio path cap so I don't know how this might impact things. I suspect not much, actually.

Hm, you run the vintage versions? Well I hear these are a tab bit more something, but I am just using the machine made, or standard version here. Honestly, this thing sounds better than it ever did. There is a clarity that I just dig.

[WhopperPlate]

I have used the standard and the vintage and there is great deal of difference between the two IMO. Standards are more broadband, where the vintage have a more pronounced "vintage" smooth midrange. They both sound and feel great. I like to combine the two and use them for different parts of the amp.

I think I might try putting the vintage sozo in the same spot you did and see what happens; try and keep all the high end harmonic content in the distortion while smoothing it out before the PI.

[rooster]

Hm, yeah, I kinda hate hearing that the two versions are noticably different. But then I do like hearing it from someone who has tried them both and says he can hear a difference. I am actually looking at picking up a few more of these for other amps I have built. Yes, at this point I am impressed by these caps. Hm, if its true that there is a touch more midrange from the vintage version, this is very good to know, too.

Well, I think its good we live in an age when something like this, a new version of an old amplifier cap, is deemed worthy of a rebirth. To have some options to choose from is a great thing. Thank you for the comparative review, Charlie, I was wondering about that. Oh, another thing, the .068 cap that is available from Sozo, the one that might be used on V1 for the 'high gain' channel of a Marshall? I'm wondering - if you heard any of your amps with something else first - did you hear any difference, the Sozo vs. say, a poly cathode cap from someone else? Here I will admit that I am doubtful there would be a sonic difference. Do you have some experience with this swap?

[JamesHealey]

The vintage sozo's sound far superior to my ears compared to the standard ones.

[WhopperPlate]

Rooster, it's my pleasure.

I have used the vintage sozo .68 in place of the std, but I swapped out all the standards at the same time for vintage so I can't tell you specific details on that cathode cap affect

(BTW that amp was too smooth and practically muddy with all vintage sozo, probably would've changed with break in and different speaker cab but I didn't wait before I started swapping components).

I have swapped out the 330uf cap for BC and Xicon brands and have to say the difference exists there. The BC cap made the amp feel a bit more sluggish and not so responsive, whereas the Xicon made the amp feel more lively, even on the split cathode bright channel!

On the Metro forum I have heard of a fella swapping out a .68 sozo std for a .68 vintage mustard and claiming he heard a huge difference.

If there is a difference between the same type capacitor I'm sure there would also be a difference with alternative composition caps. I think it's worth a try to check out alternative capacitors in cathode positions for tone shaping.

[rooster]

Charlie - Hm, interesting about the Sozo vintage swap maneuver. My thing is the midrange with any cap I think. I mean that I don't want too much 'flubby' midrange in the amp in general, from the circuit, and I sure don't want to hear that I picked up too much from a particular cap. So along with what you said earlier, I understand that the vintage Sozo has a bit more midrange than the standard version - and I will be thoughtful about that.

But yes, to all, I should try them out.

Isn't it interesting to think that, here Sozo is telling us to burn the caps in for 100 hours, and perhaps this is suggesting that the caps are a bit murky (as in your Plexi situation), so the break in is supposed to make them brighter or clearer? And then my experience is that the standard Sozo is bright from the gate and tend to smooth out after burn in. Makes for some confusion, eh? Well, its for sure they are selling caps like madmen. In fact, I think Sozo should be more specific here as what we will hear in either case, after the caps are burnt in. I see the grapth on their site - oo, pretty - but why not post a sound clip? Eh, not to throw too much water, but I do think they are a bit mysteri-(s)ozo here overall, not even showing the guts or wrap process of their caps. Do they think I am going to try to make one? BTW, did you see where some guy was selling individual Sozo caps on ebay for twice what Sozo sells them for? And then nicks people for a huge postage fee as well? Thankfully Google/Bing are here. OK, slight rant over.

[WhopperPlate]

All I know is that John Sozo worked very hard scouring for old mustards to properly recreate the legendary cap and I think the product speaks for itself. A lot of people at times seem to be skeptical on one level or another, but the caps sound wonderful and definitely take some time to break in. And the rate of sales and notoriety definitely speak volumes as well.

Guys like John Sozo and Jim from Scumback speakers have done a great deal of work so I don't have to spend vintage money and I for one am very appreciative. Semi rant over

If you happen to swap in some different caps let us know, huh Rooster. I'll document my findings as soon as I make the change.

[Big Jim]

Hey Fellas,
I have Sozos in my Metro JTM45 and the amp simply oozes mojo. I did however include the Sozo caps in the original build, so I dont have anything to compare too. Also, I've had the amp for like two years, and it still is getting better and better.....Settling in nicely.
Jim

[M Fowler]

I used Sozo caps in my Express combo build a year or so ago has a different tonal voice then the head I did with OD caps.

[WhopperPlate]

Hey Fowler, I'm sure you've posted this elsewhere, but could you elaborate more? Appreciate the time.

Jim, are those vintage or standard in the JTM45?