Dyna Comp Help

[dstrats]

Hi all,

I own a Dyna Comp, bought in '04 or so. I like it enough I suppose, but I've always been curious about vintage models and components and how I might better my Comp tone and function.

Here's my board:



Ok, first off, what is that adjustment pot for? What does it effect? There are 5 transistors on this board all being the Dunlop's fav tranny, (being that those trannys reside in my Vox wah too), MPSA18. One IC chip, CA3080AE H 0332.

So, being that everything besides the kitchen sink is soldered to this board, is there any way to make this pedal a tru-bypass? The switch is soldered to the board via 6 contacts. I notice when a switch is wired for T-B, for this case; a wah switch, the most left lugs (or bottom depending on the direction of the switch) are wired together with a piece of a resistor leg or something, then the other 4 lugs are then connected to the appropriate wires. Could I do that with this comp pedal too? Hypothetically, could I connect a wire between two of the contact on the board so it would look like a wah switch? If not, is there another way to T-B this pedal?

Are there better trannies I could use for this pedal? There are a bunch of resistors on this board. All of them 5 banded. Are there any other resistors that might help the tone and feel of my comp?

Well, that's all the questions at this time. I look forward to some replies. Thanks!!!!!!!

[KrazyKarl]

The Monte Allums mod I did sounded fantastic (before my dyna comp went into broken mode, not because of the mods.) He changes out some of the caps for better quality ones, changes all the transistors (don;t remember what they are) and some of the diodes. I'd say it's definitely worth the 20$. Sounded amazing.

[dstrats]

Well,

OK, thanks bro.

Take care.

[jkokura]

http://www.tonepad.com/project.asp?id=10

If you head there you'll be linked to a project that is both the Ross Compressor and the Dyna Comp. It would be interesting to compare your circuit to that...

Anyway, the trim pot is for biasing the IC I think. If you look at the schem on tonepad, the Power to the IC goes through the wiper of the trimpot, which would indicate that it helps set the power level to the IC. I've never really examined it even though I've built a few Ross comps. Cool.

Your resistors are fine. I am surprised to see that MXR is using good Metal film resistors, but we all use those on our builds so there's no worries there. That's what you want in a pedal. The caps could be upgraded. I see Tantalum and Ceramic, so if you wanted to look at Aluminum Electrolytic and Film caps, that could help lower noise. The Transistors are probably fine. You could switch them to 2N3904's, I don't know what this would do over the MPSA18's. I think they're similar, but I'm not a transistor expert. Look at their data sheets if you'd like more info.

As for true bypassing it, what's likely in there is a 2PDT switch. With an LED, the simplest method for true bypass would be to change the switch out for a 3PDT. Having a 2PDT switch in there probably means there's a buffer in there. It's pretty typical. Before you go and Truebypass the pedal (a fairly big hack I think), really test it out and see if the buffer sounds bad. I'd bet it doesn't, but a true bypass looper would help you. Leave the pedal off and switch it in and out of the circuit. My bet is that you'll think it sounds better, but I don't know what your experience will be if you try.

Jacob

[Fender3D]

...The caps could be upgraded. I see Tantalum and Ceramic, so if you wanted to look at Aluminum Electrolytic and Film caps, that could help lower noise...

Noise? Caps? 
If you suggest swapping tantalum with aluminum caps 'cause the formers broke early than latters (it's a matter of years btw) I could agree with you, but caps causing noise? in a compressor pedal?

The Monte Allums mod I did sounded fantastic (before my dyna comp went into broken mode, not because of the mods.) He changes out some of the caps for better quality ones, changes all the transistors (don;t remember what they are) and some of the diodes. I'd say it's definitely worth the 20$. Sounded amazing.

10caps, 5 trannies and 2 diodes are worth 20$??
I'll provide plenty if you're happy with it 

[JDoyle]

Caps don't cause noise. 1uF films are rather large. 1uF electros aren't an upgrade from tantalums. If you can fit 1uF films that would be an improvement, but my bet is the difference is slight.

A true bypass looper as suggested is probably the easiest way to get TB. Otherwise you are going to have to break out a Dremel to fit the new switch. Even then, the input impedence is high enough that I don't know if one could hear a difference between TB and stock. Certainly not without doing a side by side comparison.

To be honest - with metal films already in there, it is probably already 89% of the way to being as good as possible. 1% is putting in film caps. You have to ask yourself if the cost and difficulty involved with film caps is worth 1%. My own answer would be no. Yours may be different. The last 10%, in my opinion, would involve auditioning several CA3080s for noise and choosing the best one - and then ensuring that there is a 0.01uF film cap soldered directly to the V+ and V- pins on the CA3080 on the underside of the board.

Regards,

Jay Doyle

[dstrats]

Wow,

Great replies, thanks guys.

To be honest, I just wondered if there was away to make mine sound more "vintage" or better, but going by what y'all have been posting, I'm thinking it's just not worth any mods being that I prolly won't hear too much of a difference. It's not like I've played all that many Comps. I've played through a Analog-man comp and I thought it was too compressed, the Comp I own I felt was more to my liking, might be crazy but there you go. I just wondered if there was something I can add or subtract to better the unit being that I don't trust Dunlop for effects all that much so...

The bypassed tone is not too bad with my Comp. I do need to invest in some T-B Loopers for some of my pedals (Fuzz Face especially), so once I get a few I test the comps bypassed tone with the true bypassed tone. I suppose I was seduced by Dunlop's release of the '76 Dyna reissue with the "tin-can" CA3080. I guess I figured there was a way to make mine just as good as that one without having to pay $180 or so.

Either way, thanks to all the great replies. This site rocks!!!