Here's a couple shots of a Dyna Pas modded that I picked up recently. It has a bizarre outboard power supply with the stock transformer, a filament transformer and a choke. In the unit it has all switches bypassed and a new volume switch and mods on the power supply filter capacitors with diodes ect. The boards are original and I might replace them with upgraded capacitors, and the rca's on the back are stock which I will replace as well. Haven't listened yet but I will post a review at a later date. Right now I'm going to clean it up and check all voltages...anyone seen a power supply like this?
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
With your posting photos approaching a half a megabyte in size I'm not going to even talk to you.
751kB total! 
Jeez! Took 7mins on my dial up, At least 10 I think, lost track of the time! Watch the size of your pictures. Most of us will get bored and switch threads! 😀
Wayne
Jeez! Took 7mins on my dial up, At least 10 I think, lost track of the time! Watch the size of your pictures. Most of us will get bored and switch threads! 😀Wayne
Sorry guys, I resized the originals, but the server seems to save them and I can't edit my post.
Peter
Peter
The powersupply looks like its for an amp not a preamp! Looks like a 5AR4 or similar as opposed to the little skinny rectifier tube that comes stock. Overkill to say the least. Change out all the caps and resistors and you will be very happy with it. All the noise will be gone(well almost!). Use only metal film resistors and caps, not carbon comp unless you like the hiss and overly warm sound. The big choke is a nice touch but again overkill. There is also a seperate filament transformer which can be switched on seperately and save tube life.
The rectifier is a 6K5. It has a couple chokes for filter supply. The capacitors on the line stage are Aerovox, Astron, and Sprague Black Beauties. I suppose I should replace them with newer ones (although they don't appear noisy), and the carbon resistors. The volume knob is a stepped attenuator but appears to use carbon resistors (not sure why)? Any ideas why use carbon comps for a stepped attenuator...it doesn't appear to be a kit either.
That is a stereo width selector that has narrow to wide separation. I think it's a 6X5 rectifier.lpd said:
Your right the rectifier is a 6X5. The volume switch is a stepped attenuator though. The blend switch is disconnected.
Hi Peter,
First of I don't have any experience with units like you have but I just couldn't resist making one remark. MarkP suggested to swap resistors and caps straight away but I wouldn't go that far just yet (sorry markP, not to offend). Those resistors sort of resemble 'Allen bradley' resistors to me (only from the pics i've seen) and those seem to be rather highly regarded. So until you're quite certain what they are i'd be rather carefull with em. I don't know what kind of caps those are but they just might be some of the well appreciated paper in oil caps. I'd try testing them for leakage first, before you trash them. In other words someone has obviously modded this unit and I wouldn't disregard his mod's straight away, I'd listen to it first (after checking those caps etc.) and then go on.
As said before i just couldn't resist to be cautious
Regards
Joris
First of I don't have any experience with units like you have but I just couldn't resist making one remark. MarkP suggested to swap resistors and caps straight away but I wouldn't go that far just yet (sorry markP, not to offend). Those resistors sort of resemble 'Allen bradley' resistors to me (only from the pics i've seen) and those seem to be rather highly regarded. So until you're quite certain what they are i'd be rather carefull with em. I don't know what kind of caps those are but they just might be some of the well appreciated paper in oil caps. I'd try testing them for leakage first, before you trash them. In other words someone has obviously modded this unit and I wouldn't disregard his mod's straight away, I'd listen to it first (after checking those caps etc.) and then go on.
As said before i just couldn't resist to be cautious
Regards
Joris
I actually have a PAS and find that the resistors are usually not ABs but just carbon comp junk. They are the source of most of the hiss in the amp. Carbon comp resistors are very sensitive to heat and dont age well in general to the point that they are prone to changing value by over 10% in time. At the very least measure all the parts to see if they are in spec before you turn it on.jazz said:
Hi MarkP,
You are quite right about the technical disadvantages of those old carbon comp's, which is one of the reasons i don't use em. As said i don't have any experience with this unit so I'll trust you're judgement about those resistors. Indeed maesuring them is a good advise before any listening (ie turning on the unit). Yet those resistors do seem to have a certain 'character', which is why some people like em i guess. That's why, if feasible, i suggest he listens to the unit before making changes. If he likes the sound modern carbon film types like riken ohm or kiwame might be a possibility. As far as I know those resistors don't have the traditional disadvantages of carbon comp's.
As said i'm just i little cautious and suggest to be carfull
regards
Joris
You are quite right about the technical disadvantages of those old carbon comp's, which is one of the reasons i don't use em. As said i don't have any experience with this unit so I'll trust you're judgement about those resistors. Indeed maesuring them is a good advise before any listening (ie turning on the unit). Yet those resistors do seem to have a certain 'character', which is why some people like em i guess. That's why, if feasible, i suggest he listens to the unit before making changes. If he likes the sound modern carbon film types like riken ohm or kiwame might be a possibility. As far as I know those resistors don't have the traditional disadvantages of carbon comp's.
As said i'm just i little cautious and suggest to be carfull
regards
Joris
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