REVIEW (long): Caps, resistors & parts on my 1987x board

gnugear · Post by **gnugear** » Wed Jan 21, 2004 7:04 pm

Greetings,

I just completed my first point to point board 3 weeks ago, and I'm still tweaking on a daily basis. But not because I'm unhappy with the sound ... just the opposite! I'm more intrigued with the endless tonal possibilities. I’ve swapped caps and combinations of caps at least three times, and I'm still trying out different resistors. I’ve made over 50 clips, documenting the different values and brands, so I thought I'd summarize my experiences in hopes that you guys can share as well. In fact I’m COUNTING on you to share, because my wife is at the end of her rope and might break my tubes if she hears me play the same damn riff again!

My benchmark tone is EVH's magic Marshall, and in particular, the tones off of VHII. So with that in mind, and volume on ten, here are my impressions. Remember that tone is subjective, so what I find pleasing, you might hate … especially if your idea of a pleasing Marshall tone is along the lines of C.C. DeVille. Isn’t it ironic that my wife finds none of it pleasing. She often refers to my amp as “the bomb”. “Hey, how’s your bomb coming along?”. “Are you going to come up for dinner, or are you still working on your bomb?”

On with the review ...

CAPS
Mallory 150s:
I didn’t like these, even though they seem to be the standard replacement cap for Marshall. Everyone else seems to love em, so hey, what do I know!! I thought they were grainy with a pronounced midrange. The low end was soft and the words plastic and chewy come to mind. The notes also seemed blurry and confused compared to the other caps I tried. They were darker than the Orange Drops and less detailed. They didn't do anything wrong ... they just weren't very inspiring.

Sprague Orange Drops:
These had a flatter frequency response and a much tighter low end. I could get a nice "thunk" out of my cab when hitting the low E that I couldn't get out of the Mallorys. There was also more clarity and detail, but this came at the expense of added brightness. I’d almost say the treble was “spitty”. They definitely had more character than the Mallorys and the tone seemed more alive and touch responsive, even when blazing through lame renditions of “Eruption”.

Mystery Cap (X):
Okay, I hate to do this, but the person that told me about these made me promise not to reveal the name. That being said, the X caps flat out rule!!! They have all the good characteristics of the Orange Drops, but sound smoother and more refined. Kind of like comparing wine to beer. Yeah I know, you’re saying, “Beer and Van Halen are a perfect mix” … but you should try wine while playing “Beautiful Girls” and “DOA”! They just sound more pleasing to the ears. The low end stays smooth, but retains a tight feel that doesn’t get flubby. The grain that I heard with the Mallorys is totally absent … almost like the caps have less of a sonic signature than the others.

I also tried every possible combination of Mallory/Sprague, Mallory/X, Sprague/X, Mallory/Sprague/X, and the X caps always came out on top.

Silver Mica vs. Ceramic disk:
My Metroamp board originally had Silver Mica caps throughout, but I changed them for ceramic disks. I think they sound smoother and less gritty. Seems like the Silver Mica disks pass along every single anomally in the chain, and that’s not always a good thing in my book. I made one clip where I swapped out the Silver Mica above the output coupling caps for ceramic, and the difference was quite noticeable. I was actually quite shocked at how much smoother the ONE ceramic cap sounded. I intend to play around with this a little more because it seems like a good way to fine-tune the sound of the other caps. For instance, if the Orange Drops sound too bright, you can knock em down with a ceramic disk, or visa versa with the Mallorys. I’m totally guessing here, so if I’m off my rocker, feel free to correct me.

Xicon vs. Sprague Cathode Bypass Caps:
The verdict is still out on this one, but I think I like the Xicon’s better! Remember I’m trying to duplicate EVH’s amp, and he had a 330uf cap on V1 AND V2. I’ve been told that the value of these caps are so high that it doesn’t really matter if you use a 250uf or a 300uf. I had some Spragues and thought they looked really cool with their black barrels and green writing. They looked like something from the Green Hornet TV series. Just for the hell of it, I tried using one of the ugly baby blue Xicon’s I had laying around. Well, I might be smoking crack (or moved my mic by mistake), but I think the Xicon’s sounded better. They didn’t have any more gain, but I did hear the mid frequency shifting. They also have a hollow sound that seems to have more personality than the flatter response of the Sprague’s. Think VH1 vs. VHII. I need to do a test with both Xicon’s in place before I make too much of a deal out of this.

Next came varieties of .022, .0022, .68, and .1 caps (and all the different combos). I ended up with .022s throughout, with .1s for the output coupling caps. My 50 watter tends to sound “smaller” than my ’74 Super Lead, so I’m always yearning for more beef. Using .0022s made the amp sound too lean. Interestingly, with the Mallorys, I felt the need to go to .0022s, but with the X caps and their added clarity, I could stay with .022s and .1s!! Don’t you wish I could reveal the name!

RESISTORS
I can’t really say I hear the difference between carbon comp and carbon film throughout the board, so no comment! That being said, I did try a gain mod that required the use of a 1M resistor, and I did swap that one in and out with carbon comp and carbon film. Carbon comp sounded SLIGHTLY smoother than carbon film. “Slightly” is the operative word here.

I’ve changed a few other values throughout, but again it’s a subjective thing because I’m going for a particular tone.

FILTERING
I tried lowering the filtering but found that the sound was too soft for my tastes. I cut the jumper wire on the 50/50uf cap closest to the edge of the chassis by the HT fuse (see how little I know), so it lowered it down to 25uf (or so I’m told). I just got a 32/32uf cap that I might try out, but I’m not holding my breath. I’ve heard that the 50 watters are much different than the 100 watters, and filtering is a different beast with those amps.

NEGATIVE FEEDBACK
This is another area where I went mad scientist and tried every conceivable combination of resistor values and impedence tapping. I connected the negative feedback wire to the 4, 8, and 16ohm speaker taps, and also raised and lowered my negative feedback resistor from 47k to 100k. I finally settled on the 100k resistor connected to the 8ohm tap. How’s that for original!

RECTIFIER DIODES
Wow, am I a geek or what!! Never in my wildest dreams did I ever think I would get excited about rectifier diodes. I just read an article by Don Butler, and he said that he prefers using FRED diodes in place of the cheapy IN4007s that are found in the typical Marshall. Don used words, like “improved harmonics, better touch sensitivity, and improved dynamics”. I could feel the excitement building and sure enough, I started having wet dreams of FRED diodes! Damn, I just HAVE to try them! I’m waiting to confirm the type with George before I buy them, and then I’ll report back.

Lastly, I bought a Mercury Magnetics choke. Curiosity got the better of me, and since they’re not that expensive I’m going to try it out. It’s still not here yet, so I’ll report back if it sounds any different from the stock choke. I’ve already got a OEI output transformer so I couldn’t really justify buying a MM just to see if it was different. Someone posted some clips comparing the two, and as fate would have it, I preferred the MM. We’ll see if I cave in and buy one later on.

There you have it. Thanks to George for answering all my stupid questions. You have to remember that 6 weeks ago, I didn’t even know what a multimeter was, or how to use a bias probe, so his patience was beyond the call of duty. Also thanks to Stan (bmf5150) for encouraging me to build a kit and for listening to 50 clips of the same riff over and over and over again!

chris

Post by **VelvetGeorge** » Wed Jan 21, 2004 7:39 pm

Absolutely superb review Gnugear. I answer emails and phone calls every day asking these types of questions.

Now if I could just stock those mystery caps.........

One note: the difference in those electrolyitcs may be due to differences in value. It would be worth measuring their actual values.

George

Guest · Post by **Guest** » Thu Jan 22, 2004 11:57 am

Gnugear,
Wow, what a review. You've come a long way in only six weeks. Obviously you really enjoy what you're doing. That's what really makes the difference between someone who's got it, and someone who does'nt.
You gotta leak the info to George about those mystery caps, it's too damn painful to be reading about this stuff that's out of reach.

Anyway, the next thing you gotta try is to get a repro aluminum chassis, and see how it's non-mag properties compare to steel. Then of course, since you've come this far, you should spring for the MM OT, and document that.
Again, great volumn of info,
Fritz

gnugear · Post by **gnugear** » Thu Jan 22, 2004 12:45 pm

That's my next project! I'm still saving up my money for a 100 watter with aluminum chassis, lay down PT, etc., I've finished the board already, but the transformers are killing me!! I wish they weren't so expensive!!

chris

Guest · Post by **Guest** » Thu Jan 22, 2004 2:23 pm

Chris,
Great job!!!This will help alot of other out!!!I listen to all of your clips and have to agree with you!!the mystery caps are the best..After i get my output trans back from ****** im going to try those myst caps and some mustards!!What zicon do ya like?
stan

gnugear · Post by **gnugear** » Thu Jan 22, 2004 3:46 pm

Stan!

George is sending me another 330uf Xicon, so I can try BOTH of them at the same time, ala EVH (I currently only have one). I'll make a clip comparing them to the 250uf Spragues. I should be able to do it in the next few days.

Here's an interesting tid bit. I was reading through a lot of your old posts where you were trying out the 250uf, 330uf, .68uf, and NO bypass cap. I remember you saying that the higher values made your amp too wooly sounding, resulting in your need to lower some of the .022s to .0022s.

Well, I just played this morning and actually turned my bass up about half way. I usually have it on 0 because my amp would fart out. I'm not sure if the mystery caps are helping out, but I'm not getting the woofy sound that I used to!! In fact I actually like the added fullness ... and that's with .022s throughout and .1uf for the output coupling caps. I'm positive this would have been a blurry mess in the past (amp on 10). Maybe those mystery caps are helping out more than I realized.

I also forgot to mention in my "Negative Feedback" section that going from 4ohm to 16ohm increases the dampening of the amp, making it tighter. I think you also loose a little gain in the process. At the same time going from 47k to 100k for the negative feedback resistor increases gain. It's a real juggling act to get the right gain and openess, without it sounding too stiff or too sloppy.

chris

Guest · Post by **Guest** » Thu Jan 22, 2004 11:35 pm

Chris,
I noticed when i changed my feedback resistor from the 47 to the 27 the amp was much tighter,i dont remember if i lost any gain..i like the the 47 the best..i will have to try everything over with the new trans and choke..back to the begining!
stan

Brentsp · Post by **Brentsp** » Wed May 04, 2005 1:29 pm

Awesome stuff Chris. I guess now that its over a year later the mystery cap is Sozo am I correct?

tonebucket · Post by **tonebucket** » Wed May 04, 2005 2:50 pm

gnugear

clips clips clips??????

have you a diagram to share of your mode's?????????????????????

gnugear · Post by **gnugear** » Fri May 06, 2005 1:53 am

Wow, when did this become a sticky!

Hey Brent, those "mystery" caps were the Solen Fast Caps. ****** told me about them and made me keep it a secret. I don't think it's that big of a deal now. This was all done before the soZos came out, so I have to put the soZos at the top of my list for favorite caps. I've also gone through the Auracaps, and real mustards. I still like the Solens a lot and would use them if soZo wasn't around. To my ears the soZos do everything the Solens do, but they add a sweeter color to the sound. Both have a lot of clarity.

And to add to the list, I really like those BC electrolytics. Maybe it's the different value, but I swear they sound better than the Sprauges. I also discovered the Dale/Vishay resistors and prefer those to carbon comp.

I also think those FRED rectifiers rule. I can't believe it took an entire year to try them out.

Now I've ditched the 1987x and I've restored my '74 Superlead, built a metro '67 clone and rebuilt a 2001 SLP. I still can't keep my hands out of any of them.

sub · Post by **sub** » Mon May 09, 2005 2:15 pm

gnugear wrote: I just read an article by Don Butler, and he said that he prefers using FRED diodes in place of the cheapy IN4007s that are found in the typical Marshall.

FRED??? is it "Fast recovery diode"?
What types can i replace 1N4007?

Thanks

Sub

Billy Batz · Post by **Billy Batz** » Mon May 09, 2005 3:48 pm

Do a search for FREDs. Youll come up with quite a lot.

sub · Post by **sub** » Mon May 09, 2005 4:12 pm

Billy Batz wrote:Do a search for FREDs. Youll come up with quite a lot.

ok min. 1A, min 1000v
good?

Stratosaurus · Post by **Stratosaurus** » Thu Jun 09, 2005 9:32 pm

gnugear wrote:Well, I just played this morning and actually turned my bass up about half way. I usually have it on 0 because my amp would fart out. I'm not sure if the mystery caps are helping out, but I'm not getting the woofy sound that I used to!! In fact I actually like the added fullness ... and that's with .022s throughout and .1uf for the output coupling caps. I'm positive this would have been a blurry mess in the past (amp on 10). Maybe those mystery caps are helping out more than I realized.

gnugear - I realize this is well over a year later, but I'm curious about the above . . . at the time did you have a split or shared cathode arrangement.

-John

gnugear · Post by **gnugear** » Mon Jun 13, 2005 10:23 am

I had my 50 watter set up with a shared arrangement.

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REVIEW (long): Caps, resistors & parts on my 1987x board

REVIEW (long): Caps, resistors & parts on my 1987x board

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