59 Bassman RI/LTD PTP conversion

[shark_bite]

Anyone done this? I've heard of it a few times before. See any pros/cons to doing it? Just curious mostly, but then after seeing that BJr thread earlier this morning, I remembered one of the things that freaks me out about PCB amps... it's pretty easy to lose the entire circuit if you accidentally light the wrong part on fire.

Anyway, anything you know would be more than I know.

 

[RussB]

pro's, none

con's, cost

that's how I see it

 

[Billm]

That Blues Junior could be back up and running in the time it takes the epoxy to set. The "damage" is all cosmetic.

I agree with RussB that switching to an eyelet board would be a very expensive form of insurance against something that will probably never happen.

 

[shark_bite]

I always thought so too... which is why I wondered why I've seen people do it. Hence the thread. I guess I didn't really get the upside (except for PCB-paranoia, which I readily admit is 99% stupid).

 

[JDJ]

I'd only do it if you wanted to do it yourself, provided you are comfortable doing it. It would be a fun project and a great source of pride.

 

[BIGGERSTAFF]

59 Bassman RI LTDs sound great stock, and should be very reliable. There's other mods I'd do first(better iron and tubes).

 

[ben_allison]

I'm fairly certain a transformer/tube/speaker upgrade would make way more difference than modding it over to PTP.

I think a lot of people look at old amps and think, "Man, that sounds better! Must be the PTP!" when it's really the circuit design and component choices that account for the older amp's improved sonics.

 

[Mark Kane]

I think the best mod is adding a bias pot and taking out the two 22uf caps in the preamp power supply and replacing them with one 8uf cap. Easy to do and the feel of the amp improves a bunch.

 

[VaughnC]

Unless you're a tinkerer it's probably not worth the effort. If the PCB itself ever goes into meltdown you could always upgrade the board at that time.

 

[GenoBluzGtr]

I own a converted early BMRI. I love it. I don't think I necessarily love it BECAUSE it's PTP, but whatever the reason it sound HEAVENLY!

It was converted before I bought it, but I have played several other stock ones and this one sounds better. I can't guarantee that it's due to the conversion, however, because many supposedly "identical" amps sound different.

Pros? Ease of repair and maintenance. Take a PTP tube amp to any reputable tech. Quick, easy to diagnose or perform maintenance, and relatively inexpensive. Take a PCB tube amp to a tech... first you have to find one that will actually work on PCB amps, and secondly it will be more expensive (too many 'modules' that need to be replaced together or as a unit, etc..) and will likely take longer. If you're like me, and can do most minor maintenance/repair yourself, PTP is FAR EASIER to work on. If you really want to make tonal improvements, you can insert the best components when you do the upgrade and have guaranteed better tone. Much more difficult to do this with the PCB intact. The bonus? you aren't messing with a true vintage tweed bassman... no worries about destroying the originality and you can play around much easier with the circuit.

Cons? The added cost is the only con I can think of. The kit that was used to convert mine was done by a pro tech (got this info from the previous owner)... kit cost was $250, labor cost was $150. So for $400 extra bucks, I have a PTP Tweed Bassman that has all new components, input jacks, potentiometers, and wiring harness. Tube sockets, Transformers, speakers, speaker jacks, cab, knobs, jewel light are all original.

If you find a good used one, they can go as low as 600-700 bucks. Add 400 and you have a great PTP amp for about 600-700 less than the cost of a New BM LTD !

VaughnC has a great point. Pick up the amp, play it to your heart's content. If you ever have a major issue with the amp, just gut it and re-do it then. You could even buy all the pieces/parts ahead of time at todays costs.

I love mine, and although it may not have anything to do with the conversion, there is a mojo about this amp that has kept it in my possession through the most severe G.A.S. attacks. She's stayin'. I can't say that I would have gone looking for a PTP Tweed Bassman conversion, but it fell into my lap for a great trade deal and I love it. I have used it regularly for years since with no issues.

 

[jumpnblues]

"[...(except for PCB-paranoia, which I readily admit is 99% stupid).]"


I'd be very careful with broad, sweeping, statements like that unless you're prepared to back them up with very specific, concrete, and technical information. There are a lot of extremely knowledgeable people on this board who would disagree with it.
After having said that, I too would leave the amp as is. And if you wanted to "upgrade", sell or trade the amp for one of the high end Bassman clones such as a Victoria. Do they sound better? To my ears, yes. To yours maybe not. It will likely be easier to repair though should something go wrong. I'm not one who believes that PTP wiring necessarily imparts better tone to an amp. But I will say, taking into consideration all PCB amps manufactured, I generally like the tone of PTP amps better and they're easier to repair. There are certainly exceptions. JMHO, YMMV.


Tom

 

[imguitardan]

I wanted to bump this thread as I'm considering doing this to my '59 Bassman RI. How noticeable of a difference from stock was it (for those of you that have modded it)?

Has any one just upgraded the power transformer? How much of a difference does that make?

 

[Marty DiBergi]

I'm fairly certain a transformer/tube/speaker upgrade would make way more difference than modding it over to PTP.

I think a lot of people look at old amps and think, "Man, that sounds better! Must be the PTP!" when it's really the circuit design and component choices that account for the older amp's improved sonics.

This. I have BMRI LTD and it sounds awesome. I have tinkered with tubes and preferred the results from stock. If I wanted to change the sound further, I would look at the speakers next.

Converting *that* particular amp from PCB to hand-wired would be the last thing on my list of things to change, or perhaps fall in the "never" column.

The components are pretty much just fine and the amp sounds killer. The jacks are metal, the tubes are chassis mounted. It's a simple single channel amp. Having chassis mounted tubes is a big plus.

That said, I have a '68 Ampeg Gemini that is PCB with board-mounted tubes and it sounds great and never an electrical or reliability problem.

I personally have learned to care more about the circuit than whether electrons are carried on traces or wires.

 

[Ogre]

I put a Mercury Magnetics output transformer & choke in mine, and it sounds great.