My X10 has begun

[Colossal]

-Bright switch is still minimal effect with 50 and 100pF caps.
-Still bassy overall I think - or just too much gain. Higher voltages might help.

You might go up even higher, say 220pF on the bright. I used 220pF (might even have been 250pF, I'll have to look) on a Rocket and love it. Adds a nice and just-noticeable shimmer to the tone. Your comment about [too] much bass is interesting; this very well could be the effect of the polypropylene caps in the B+ supply. The Solens will definitely give an expanded, more punchy low end.

[rhinson]

the coupling cap from the 1st stage is probably NOT .01uf. it's probably .001 - .0022uf, or something in that range. if you have .01uf, that's probably where the too much bass/gain effect is coming from. rh

[surfsup]

rhinson I will vary that cap value, my bass pot does nothing after 20% turn.

I have a voltage problem that seems to be two-fold, but might be related (1) My unrectified AC is 335 instead of 300 (using 300-0-300) and (2) the rail voltages are all low for some reason.

I updated the schematic showing the rail on the OP, but here it is, with the picture showing the leads, any ideas anyone?

[img704]http://chicagocadcam.com/ChrisHahn/xen10/Xen10_wVVR.jpg[/img]

[img1000]http://chicagocadcam.com/ChrisHahn/xen10/VVR.jpg[/img]

[surfsup]

335vac
462vdc rectified standby off
274vdc standby on

462-274 = 190v

V/R = I = 190/1000 = 190mA is very high

P = IIR = .190*.190*1000 = 36.1watts

36 watts would have smoked the 1k5w Rs so what am i missing? The VVR must be doing something or that diode is letting it affect the V at first cap?

[rhinson]

i'm going to be building this pretty soon----without a vvr. and my power trannie is a stock ac15 type from heyboer (332-0-332 unloaded) so i'm interested to see the drop across the 1k's in the hv sec ac line. if you want to drop some voltage, you can also use a 50w reverse polarity zener diode on the hv sec ct. i'll probably do this if that stock xits 1k idea proves to be fubar----it works great. rh

[surfsup]

As I research this more, it seems the voltage drop on the AC side before rectification is going to be a larger value than if it was DC (V=IR)

AC V drop is V = IZ where Z equals impedance

per wikipedia
The voltage drop in an AC circuit is the product of the current and the impedance (Z) of the circuit. Electrical impedance, like resistance, is expressed in ohms. Electrical impedance is the vector sum of electrical resistance, capacitive reactance, and inductive reactance. The voltage drop occurring in an alternating current circuit is the product of the current and impedance of the circuit. It is expressed by the formula E = IZ, analogous to Ohm's law for direct current circuits.

So, I am going to order some smaller value resistors, figuring an impedance ratio of 2.7 based on 70mA draw, I'm at around 500R, so I ordered some 500s, 560s, 680s, and 330s

I figure if the AC drops to 300 like it should, I'll need a few values to test.

[rooster]

I think rhinson has the cappage correct. That .01 always looked wrong, .001 better.

As to the Solens caps in the power supply making the amp bassier? No, increasing the speed of the power supply does just the opposite if it contributes to the tone of the amp at all. Think of the slew rate in a transistor here as an analogy maybe.

[Colossal]

I think rhinson has the cappage correct. That .01 always looked wrong, .001 better.

Rooster,

When this thread was started, the schematic evolved from interpreting the gut shots that came from Fat Sound. The coupling cap at the time was confirmed to be a 0.01uF Sozo. For the current production model which we have dubbed Version 2, Koski changed this cap to a RelCap polystyrene and may have decreased the value. In the absence of a confirmed value for that RelCap, the schematic continues to show the original value of 0.01µF. (see attached).

As to the Solens caps in the power supply making the amp bassier? No, increasing the speed of the power supply does just the opposite if it contributes to the tone of the amp at all. Think of the slew rate in a transistor here as an analogy maybe.

I don't think the Solens are "making" Surfsup's amp bassier, but merely accentuating what is already in there.

[rooster]

Colossal - Sure, I remember that original evaluation, but I also thought that that circuit was quite different. Which is to say it's entirely possible the .01 cap there didn't add any bass because the bass was already reduced by the time it hit the .01.

This #2 version smacks more like an AC30TB channel - except - what would be a 500pf cap is changed to .01. Can you imagine how bassy an AC30TB would be if you increased the initial 500pf coupling cap by 200%?

Well, I realize, too, that nobody here has one of these amps to actually look at so speculation is the name of the game to a certain degree. So if the amp is too bassy, the bass needs to be addressed, right? That .01 to me has always looked wrong and now it seems that the build is too bassy - that cap is the quickest way to address the bass.

One last word on the Solens then. I have this really cool old Silvertone amp that I reworked more than a few times over the years. It's unique, with two push/pull 6L6 Class A amps combined to a two channel preamp (two OTs). It has great tone and great feel. Well at one time, like a kazillion years ago (1998) when the Solens caps were getting some attention, I thought, 'Hey, I'm gonna switch to these and never have to worry about changing my power supply caps again.' Yeah, I was cool. So I did this. And man, what a lesson! This amp lost everything good that it had going for it. I was stunned to learn how much the power supply caps can influence the character of an amp. I pulled them out and put the Spragues back in it - and all was good again.

To describe how the feel and response of the amp changed, and how this impacted the sound of the amp is difficult. It's one of those things. If you have tried this, then you know. If you haven't then you don't. IMO they just don't belong in guitar amps, period.

******************************************

Note, in another post I made recently, I talk about a Fender BF Vibroverb that has been worked on by Kendrick? Here in this amp, in the power supply, I found a 10uf Solens cap put in parallel with an 20uf electrolytic. ?? The amp sounds pretty good actually so maybe there is a place for the Solens afterall, not positive. I will try it in my BFSR in the future to see what I think about it in an amp I know very well. It might be that a blend of the two types in the right position and amount might be OK. ...I mention this to point out that I could be wrong, there might be a (small) place for them in a guitar amp afterall. I'll get back to you on this.

[pamaz67]

@surfsup
today I'm really busy so I 'll check the voltages possibly tomorrow
@rooster
I've built more than one fender style amp with solens in the supply and I have to say that everywhere I fitted them, I found always stunning results, compared to electrolitics.
If I can say, everything is more fast and focused. And the sound is very detailed without being harsh
I mean, probably in a Ac30 style amp there could be too much a fast response or a "hifi" sound, but in other applications solens are simply great.
So i don't thing that is possible to say that solens are degrading the sound.
It all depends on the applications.
If you fit Ferrari tires on a Civic, it's not said that the Civic will be more pleasant to drive.

Furthermore: on the coupling cap.
The x10 is a 1x12 combo, so a generous bass response could be desired also for that reason.
But Yes, with a 4x12 ( as i have tested my prototype) or even a 2x12 that cap could be smaller than 10nF.

[surfsup]

B4 I worry about railcap choice, I need to get the voltages squared away, then adjust a bit for the tone. Perhaps the 0.01 is too big. I can sub something else, not a big deal.

I should clarify my statement of "too much bass". Yea there seems to be too much bass, but this amp seems to just have more of everything. Though admittedly I haven't played it much. Geez, I haven't played guitar much at all though anything lately. Too much amp building and working.

Off to Florida for a week...thanks for your help guys!

[Colossal]

This #2 version smacks more like an AC30TB channel - except - what would be a 500pf cap is changed to .01. Can you imagine how bassy an AC30TB would be if you increased the initial 500pf coupling cap by 200%?

Yep, 500pF is probably more than enough especially for a Top Boost which the Rocket and the X10 essentially are!

[rooster]

pamaz67 - OK, as they say, to each his own. Ha! 'Stunning' is a good word here IMO, pointing out how different a tweed circuit can be with the Solens. Like I said, not a fan.

If you had a couple of players in the room, and you offered them either version amp, and they chose the Solens version then I certainly would respect their choice. I would let them have what they thought sounded best, no worries.

That said, the fact remains that there are way way way way way more tweed Fender amps out there being played (and cloned) with typical electrolytics in them. From my experience with the Solens, I tend to think that it's just another *lucky* break for Leo Fender (and us) that he built his amps when he did, and had only the parts he chose to choose from. Amazing.

[pamaz67]

Rooster seems that also Steve carr in his Rambler amp ( IMHO one of the best amps built these days) thinks that it's an amazing choice. AFAIK you'll find in its circuit at least 3 different fender inspirations ( BF, SF and tweed).
As a parallel, let's say that using dale rn65 resistors in a tweed amp is not going to help you if you are chasing for a classic tweed tone. But it's not automatic that you'll get a bad sounding amp. It's just a matter of choices. There is no general rule.

Stunning is a word that I use with a positive meaning, but being Italian and not American probably I'm mistaking . If it's like that, sorry.
Replace it with "excellent ++" if you think is more proper in that phrase

edit never said I made tweed amps with solens. I made some kind of BF amps with such supply.

[rooster]

Ha! You used the word correctly. But to say that something is stunning is also saying that 'it stunned you'. And to be stunned is to be shocked/taken by surprise - in a good way or a bad way. So I turned your meaning around to suit my reaction to the Solens caps.

Yes, the Carr amp is praised by many and some models use the Solens caps. (If all of them use the Solens, I wouldn't know. Do they?) I have played a Rambler and I thought it sounded good. He also uses a Eminence Wizard speaker in that amp. And, FWIW, I think the combination of those caps, the circuit, the speaker, and the OT, all came together to make a good sounding and tonally versitile amp. It struck me as a 'tight' Fender sound, actually.

As to the 'feel' factor, well, it didn't hit me in the heart exactly. ?? I guess it's personal thing, no offense to Steve and his manufacturing decisions. Would I like to see if I could blind test a Rambler built with Solens vs. Mallorys? Hell yeah, I would love to do that.

Anyway, sorry if spinning that word threw you.