Jess Oliver's legacy - AMPEG PORTAFLEX CLUB part 10

[kuratacus]

inother questions, did the earlier 63's and the later with SS rectifiers share the same schematic page? AND if so, is it possible to remove the metal plate it is glued onto? the SS 63 has a clean schematic. my tube 63 has a super rusty one. but only one tray is in great condition.

[CL400Peavey]

Originally Posted by beans-on-toast

Some cabs require you to put a lot of power get them to sing. One that works well at both low and high levels gives you the best of both worlds.

That is one of the nice things about the fEARful cabs. Their tone doesnt change a lot as you feed them more power.

Originally Posted by beans-on-toast

I'm thinking that if there wasn't a reinforcing cleat in the middle of the port, maybe there would be enough room to store the amp there. Better to make the cab structurally sound though.

+1

I do set a 100 pound tube amp on my cabs from time to time. I will take the extra support.

[beans-on-toast]

Originally Posted by kuratacus

inother questions, did the earlier 63's and the later with SS rectifiers share the same schematic page? AND if so, is it possible to remove the metal plate it is glued onto? the SS 63 has a clean schematic. my tube 63 has a super rusty one. but only one tray is in great condition.

The tray has an aluminum sheet that the schematic is glued onto. You can get the same aluminum at a hardware store. I buy it in a roll in the roofing department. It is fairly easy to cut to size with some snips or scratching it and bend it back and forth till it breaks along the line. The aluminum is often glued pretty well to the amp tray. I've never tried to remove one but I suspect that you wouldn't be able to do it and preserve the schematic. The old paper pretty fragile.

The schematic for the early 63 with the tube rectifier is not the same as the later one with the SS rectifier. The power supply is different, as is the way that the speaker plug is drawn, not to mention the rectifier.

It is possible to make a repro. It takes a lot of time. You could take a high resolution picture of the NA schematic and edit it with a paint program to turn it into a B-15N one. Then print it on some art store paper to scale. Stain it with some tea to artificially age it and glue it on. Mark at vintage-blue has some nice clean redrawn schematics on his web site. You might be able to start with one of those. I've never made one for a B15 but I have done tube charts for other amps. It would be interesting to do a tube chart for the cabinet of a B-15N. I've never seen one done.

[xoir]

I'm thinking aloud while writing this post; in recent posts has discussed the option of replacing the 7027 tubes with 6550, although this is possible making some adjustments, I would like to hear your opinion, I have been experiencing lately and honestly I have to confess that I like the sound of 6L6 ** instead of 7027, two months ago I found a M15 with 6L6GB which realy surprised me, a month ago replaced the 7027's in my B12XTC using 6L6GC and I have to admit that I liked the sound since I made the change, the situation now is that I have a B18N with two 18-inch cabinets and I would like to try the 7027 by 6550 or even 6L6GC, at this point the sound of my B18N not bad , but I am not convinced, for example when I changed the 12AX7 with 12DW7 in my SVT, I noticed a big difference in tone, some times small changes can lead you to find the sound you like the most.

At this point, I discovered that the 7027 is not the sound that I like most. What do you think guys about replacing them with 6550 to keep my current wattage or sacrificing 20 watts using 6L6?

[beans-on-toast]

The tube that you use is important. With different tubes of the same make, one can perform better than another. So trying tubes of different makes can make a difference.

One of the differences between a 7027A and a 6L6GC is the maximum plate voltages specified for the tubes. A 6L6 has a maximum plate voltage of 400V; a 6L6GB is rated for 360V; a 6L6GC is rated for 500V; a 7027A is rated for 600V.

In the case of the B18, the plate voltage is 505V so either tube 7027A or 6L6GC can be used. Same story for the B12XT, the plate voltage is under 500V. This isn't the case for all amps. So it is important to look at the voltages in the amp.

I don't know if you had a typo in your post, but I wouldn't run a 6L6 in a B18 unless the amp was modified to work with the tube. 6L6GC or 7027A are fine.

One general comment, a fixed bias amp sounds a LOT better when it is biased properly. It makes a big difference. If your amps doesn't sound the way that you want it to, have the bias checked before swapping the power tubes out.

[stiles72]

'Tis the time of year for cool old Ampegs to start popping up for sale on Ebay... Here's a 1960 B15 Head

http://www.ebay.com/itm/1960-Ampeg-B...0860c03&_uhb=1

[xoir]

Originally Posted by beans-on-toast

The tube that you use is important. With different tubes of the same make, one can perform better than another. So trying tubes of different makes can make a difference.

One of the differences between a 7027A and a 6L6GC is the maximum plate voltages specified for the tubes. A 6L6 has a maximum plate voltage of 400V; a 6L6GB is rated for 360V; a 6L6GC is rated for 500V; a 7027A is rated for 600V.

In the case of the B18, the plate voltage is 505V so either tube 7027A or 6L6GC can be used. Same story for the B12XT, the plate voltage is under 500V. This isn't the case for all amps. So it is important to look at the voltages in the amp.

I don't know if you had a typo in your post, but I wouldn't run a 6L6 in a B18 unless the amp was modified to work with the tube. 6L6GC or 7027A are fine.

One general comment, a fixed bias amp sounds a LOT better when it is biased properly. It makes a big difference. If your amps doesn't sound the way that you want it to, have the bias checked before swapping the power tubes out.

Sorry my mistake, 6L6GC, not 6L6. All my amps are biased properly everytime I change the tubes, I've had low expectations in the B12XT until I swap tubes to 6L6GC, I will defenitly expect more from the B18N so I need to consider wich could be the right path 6550 or 6L6GC...

[dzaneh]

I just got myself a B-15 NC...
been read'n the post here tonight...
purty cool stuff !

[christw]

Originally Posted by xoir

Sorry my mistake, 6L6GC, not 6L6. All my amps are biased properly everytime I change the tubes, I've had low expectations in the B12XT until I swap tubes to 6L6GC, I will defenitly expect more from the B18N so I need to consider wich could be the right path 6550 or 6L6GC...

I did the two things I could to make my b-12xtc a badass bass amp. I replaced the cheap replacement speakers with some louder modern bass speakers and I ran 6550's in it. The volume and mid/high range presence is in tact with a fattened low end. I highly recommend 6550 for the job. It'll have a new depth. I also recommend a fancy new high efficiency speaker. Faital among others have great options. I've got that JBL but I'm not trying to plug it. I just think it would honestly be a ridiculously good speaker for a B-18 or B-18X and will probably not have the chance to purchase one for months if not years.. Not to say I can't hope though. I've got a job with a very good potential.

[JimmyM]

#338 dzaneh

[xoir]

Originally Posted by christw

I did the two things I could to make my b-12xtc a badass bass amp. I replaced the cheap replacement speakers with some louder modern bass speakers and I ran 6550's in it. The volume and mid/high range presence is in tact with a fattened low end. I highly recommend 6550 for the job. It'll have a new depth. I also recommend a fancy new high efficiency speaker. Faital among others have great options. I've got that JBL but I'm not trying to plug it. I just think it would honestly be a ridiculously good speaker for a B-18 or B-18X and will probably not have the chance to purchase one for months if not years.. Not to say I can't hope though. I've got a job with a very good potential.

well, I don't have a 6L6GC spare pair right now, but I could afford a 6550 GE spare wich I could use later on my SVT if I'm not pleased with the result in the B18N... the 6L6GC gives me plenitude of volume in the B12XT, at this point, I'm not entirely considering wattage... but will be a plus, I stole one vintage Jensen P15-LF for a ridiculous price the other day and I want to give it a try, need time to make the speaker ring converter to 15" in my cab... other task in queue..

Beans,
bias proof!

[beans-on-toast]

Originally Posted by stiles72

'Tis the time of year for cool old Ampegs to start popping up for sale on Ebay... Here's a 1960 B15 Head

http://www.ebay.com/itm/1960-Ampeg-B...0860c03&_uhb=1

That would be a nice amp to buy. Another one with the large hole tube cage.

[beans-on-toast]

Originally Posted by xoir

Beans, bias proof!

You have things well in hand. Normally I'd want an unbiased opinion but in this case, I'd be interested in a biased opinion as to what you think of the 6550A in the B18N.

[dzaneh]

Originally Posted by JimmyM

#338 dzaneh

thanks !

[shadven]

For sale on my local Craigslist. Looks like a pretty good deal for an SB-12 in very good shape.
http://tampa.craigslist.org/pnl/msg/3515293861.html

[xoir]

Originally Posted by beans-on-toast

You have things well in hand. Normally I'd want an unbiased opinion but in this case, I'd be interested in a biased opinion as to what you think of the 6550A in the B18N.

well, today I tested for a long five minutes run using 2x6550GE and SSR unbiased and the results are...... impressive!! that's how I expected the sound from the 18" speaker. I used to have little distortion at 11-12 o clock, I didnt want to push harder but at 13 o clock the sound was clean, smooth, deep and the speaker has a lot of low end. I'm gone to take the chance of biased and use and see how for goes.

[beans-on-toast]

Sounds good so far.

[kuratacus]

Well my guitarist is happier than happy with the 63' SS rectifier B15. has it running through an old marshall on half and it sounds amazing. meanwhile my tube 63' is happy with a second double baffle cabinet.

oddly enough the SS 63 cab still has the old foam behind the grill. and you can see a square outline where it is. when i took the grill off the visible pieces crumbled as i cleaned out the dust

[gjbassist]

I'm wanting to replace the foam gasket for the lid of my B-15T cabinet. Is this the best stuff to use?
http://www.fliptops.net/catalog/p-10...portaflex-amps

I want it to look as close to original as possible so I don't want to use foam weatherstripping.

[JimmyM]

Originally Posted by shadven

For sale on my local Craigslist. Looks like a pretty good deal for an SB-12 in very good shape.
http://tampa.craigslist.org/pnl/msg/3515293861.html

Dang, that's hot and semi-local. Wife would kill me since she's already approved the Heritage SVT.