Jess Oliver's legacy - AMPEG PORTAFLEX CLUB part 9 - Page 34

Black Sheep · #**661** 12-30-2012, 07:27 PM

If things are otherwise sounding nice, how much buzz/noise is common with these? Mine's not terrible, but more than I expected.

Anyone know where to get an isolation bushing/washer for a 1/4" jack? I'm using a jack for the speaker connection and although the ring terminal eventually goes to ground, I'd like to isolate the jack from the chassis in case that sets up a bad ground loop.

beans-on-toast · #**662** 12-30-2012, 07:50 PM

These amps are very quite when they are in top shape, hum and hiss should be next to nothing.

The ext spkr jack needs to be isolated from the chassis or else there will be a ground loop hum. If you remove the speaker cable and replace it with a jack, I still like to isolate it. It was effectively isolated when the speaker cable was in place. When the jack is grounded to the chassis, you get a fairly high current running through the chassis to the ground point. Depending on the layout, this current can induce noise in something near by. I like to keep it clean and not do that. It doesn't mean that it can't be done, a lot of amps have this.

You need one Switchcraft S1028, and one S1029. One is a washer, the other is a washer with a collar. Together they isolate the jack by not letting it come in contact with the metal of the chassis. The jack with the long bushing (neck) is a Switchcraft L12A.

stiles72 · #**663** 12-30-2012, 08:33 PM

One thing I have found with my '63, is that if I have a bass plugged into one channel, and not the other- but have that other channels volume turned up, I get some hum/buzz. Turn that channel all the way down or plug something in (second bass, ipod, etc...) and the hum goes away. This applies to either channel. Not sure if this is how all B15's are, but its the only way mine will hum. Otherwise it's dead silent when not playing.

beans-on-toast · #**664** 12-31-2012, 07:53 PM

I think that what you described is normal Clint. I hear a bit of hiss when I crank the other channel as well.

Since we have the same amp (mine has a few mods), I ran some tests on mine to see where the noise comes in. With the channel 2 volume turned off, tones at noon, with a P-Bass plugged into channel 1, if I put my ear to the speaker, I start to hear some hiss at 3 o'clock (fully counterclockwise is at 7 o'clock). At full volume, the hiss gets a bit louder. There is no hum. Turn the volume back to noon and you can't hear any hiss or hum. Leave the instrument plugged into channel 1, volume at noon, turn up the channel 2 volume. With my ear to the speaker, I hear the hiss starting at 3 o'clock. Stand a few feet away and it can barely be heard.

I haven't touched the tone module or pots on my amp. I think that if these were rebuilt there would be less hiss. A low noise tube would also help. Since I can turn the amp up to noon without any noise, I figure it is good enough as is and I'd rather leave the tone section stock.

Black Sheep · #**665** 12-31-2012, 08:05 PM

I am getting the least noise with the hum pot at about 50%, but the rest is more of a ground buzz. I'll probably go in and try to thoroughly check connections and such.
Since I did the 3-prong plug mod and eliminated the ground switch and black-cat cap, I wonder if there is anything else I should do. Is there any bonding or other touch-ups that should be done when going grounded plug? I've found that some of the buzz goes away when touching the metal parts on the bass or touching the exterior amp case, but some stays. (btw, buzz is not there in Standby)

JimmyM · #**666** 01-01-2013, 01:59 AM

Just wanted to say happy new year, everyone! Rocked my 64 tonight because the audience paid a small fortune to get into the party we played and they deserve a little better than a practice amp

Looks to be a good year for Ampeg fans with news of a People's B-15 and a 100w tube amp on the horizon. Can't wait to see what happens at NAMM. Hope it's a little more exciting than last year...Micro CL was cute, but let's make with the tubes already!

christw · #**667** 01-01-2013, 03:09 AM

Jimmy, I can't help but think the 100w tube amp and the more affordable B-15 are one in the same? Or are they not?

Oh yeah... happy new year!

JimmyM · #**668** 01-01-2013, 03:16 AM

Hodgy said the B-15 was the same circuit and cab as the Heritage with the 1964 and 1966 thing. Black instead of chrome, and I assume PCB instead of handwired turret board. So nope, it and the 100w head won't be the same amps.

Duke21 · #**669** 01-01-2013, 03:20 AM

Quote:

Originally Posted by JimmyM

Hodgy said the B-15 was the same circuit and cab as the Heritage with the 1964 and 1966 thing. Black instead of chrome, and I assume PCB instead of handwired turret board. So nope, it and the 100w head won't be the same amps.

Happy new year Jimmy! And while you guys are waiting for the new B15, we went from the virtual 100W B15R on Amplitube to the 25/30W B15 1964/66 on Jamup.

beans-on-toast · #**670** 01-01-2013, 08:56 AM

All the best to everyone in the new year.

I hope that Loud follows through and offers the new B-15 and V4B. It will be interesting to see what cab will come with these amps. Will the B15 have a double baffle design or will it be a modified PF-115? Same for the V4B, 215 or maybe a modified PF-410?

Zoomie · #**671** 01-01-2013, 09:04 AM

If anyone cares, CL ad for a B-15N Elizabethton, TN. The asking price is not for anyone with a weak heart.

I have no dog in the hunt. I am close enough that if anyone wants me to take a look (I am tube amp ignorant so you would have to walk me through the walk thru) I will happily do so, out of respect to all those here that have helped me.

Hit me up via email if you can't live without it and I can take a drive for you.

http://tricities.craigslist.org/msg/3512059586.html

beans-on-toast · #**672** 01-01-2013, 09:36 AM

Quote:

Originally Posted by Black Sheep

I am getting the least noise with the hum pot at about 50%, but the rest is more of a ground buzz. I'll probably go in and try to thoroughly check connections and such.
Since I did the 3-prong plug mod and eliminated the ground switch and black-cat cap, I wonder if there is anything else I should do. Is there any bonding or other touch-ups that should be done when going grounded plug? I've found that some of the buzz goes away when touching the metal parts on the bass or touching the exterior amp case, but some stays. (btw, buzz is not there in Standby)

You are doing the correct thing with the hum pot. Adjust it to minimize hum. This only affects hum from the heater circuit.

Not sure if there is anything else that you can do for the three conductor power line conversion. The safety ground wire should be grounded to a location on the chassis on its own. I use a ring terminal on the ground wire and connect it to the long threaded post that the tube cage mounts on. Do not connect it to the ground bus.

The buzz that goes away when you touch the strings is related to something else. This sort of buzzing is sometime difficult to figure out what the problem is. It goes away when you touch your strings or the chassis because you are grounding yourself. You are acting like an antenna. Sometimes this kind of buzz can be fixed or reduced, sometimes it can't.

A bad electrical connection in the wall can cause noise so trying a different circuit could help. Try moving to a different room. Fluorescent lights or a light dimmer can throw off noise. Turn them off.

On the amp, check that your ground bus connection to the chassis is clean and tight. This is usually at one of the input jacks. Sometimes corrosion gets in between the hack and the chassis and causes a problem. If the jack nut is loose, it can cause a buzz as well. Also check that the volume and tone pots nuts are tight. Again you want a clean connection to the chassis because there are grounds there as well. Those big star lock washers that they use have a habit of oxidizing. This impedes contact with the chassis so they should be cleaned or even better replaced with new ones. Once these washers start to oxidize, it doesn't take long for it to set in again once they are cleaned.

It could be your pickups. Does it happen regardless of what bass is plugged in? If it is just with one bass, it could be that it has single coil pickups that are simply prone to noise. Not much that you can do. It could be that the electronics have problem, perhaps corrosion like above, or it could be that the cavity and pick guard needs to be shielded. Does changing the instrument cable help? Try a shorter one, lay it flat on the floor. Snaking is ok but don't let it loop over itself. Does changing your position help? That is, turn 90 degrees or move to a different location.

JimmyM · #**673** 01-01-2013, 02:51 PM

Quote:

Originally Posted by Zoomie

If anyone cares, CL ad for a B-15N Elizabethton, TN. The asking price is not for anyone with a weak heart.

I have no dog in the hunt. I am close enough that if anyone wants me to take a look (I am tube amp ignorant so you would have to walk me through the walk thru) I will happily do so, out of respect to all those here that have helped me.

Hit me up via email if you can't live without it and I can take a drive for you.

http://tricities.craigslist.org/msg/3512059586.html

For $1500 it needs to have the original tolex or at least blue check replacement tolex! Mine looked that when I got it except for a bashed in power transformer, and I paid $150.

stringmaster54 · #**674** 01-03-2013, 02:13 PM

Have a line on a mid '60's (I believe '64) SB-12. What should I be looking for? What's the current value (it appears to be pretty clean). Are they giggable for small venues? Worth picking up? Any other info? (I cruised this thread).
Thx!

**ddbassGA** · #**675** 01-03-2013, 04:39 PM

I love my SB-12. It is my always ready amp in my home studio/music room. I paid about 750 all together, purchase, ship, and a good once over at the tech (caps & 3 prong).

Ric Vice · #**676** 01-04-2013, 06:01 AM

Quote:

Originally Posted by stringmaster54

Have a line on a mid '60's (I believe '64) SB-12. What should I be looking for? What's the current value (it appears to be pretty clean). Are they giggable for small venues? Worth picking up? Any other info? (I cruised this thread).
Thx!

I once owned a SB-12 and found that while it's a more portable amplifier than the B-15N, it sounds quite different. Because it has different porting, and a smaller cabinet, it has a brighter voicing than the B-15, and not quite as much bass response. Ampeg designed and built that amplifier, as a companion for
their Baby Bass (SB actually stands for string bass)with it's character and tone quality. So, it sounds a lot better with Double Bass, to my ears, than it does with the electric. My comparison of the two is based on having both of them at the same time and gigging with them. Each of the amps I owned, had stock speakers, so the B-15N used a CTS and the SB-12 had a Jensen. I've often wondered what the SB-12 would sound like with a newer driver. Ampeg did build a two channel B-12, with a B-15 head, and a different cabinet, but it still wasn't a double baffle porting system, like the B-15N. My guess is that building a Double Baffle Reflex cabinet, with a 12" speaker would have not been cost effective, and possibly made the cabinet larger, so it would have come close to the size and shape of the B-15N cabinet anyway. Just my take. The SB-12 is missing some of the warmth that the B-15N has and doesn't have as much headroom.

Ric

AverageWhiteBassist · #**677** 01-04-2013, 08:31 AM

Here is my B-15NC from 1964. I love the amp, it continually surprises me how flexible the amp is. Channel 1 for more vintage vibe, channel two for more bite, blend the two and get exactly what you want in between.

As far as recent posts, I had a SB-12, closer to the channel 2 sound from what I remember, but a different animal all together. My friend has one and swears by his for recording, etc-so much so that he parted with this '64 and sold it to me. So, to each their own Ampeg.

portaflexer · #**678** 01-04-2013, 08:35 AM

Quote:

Originally Posted by stringmaster54

Are they giggable for small venues?

I read somewhere that Everett Hull (founder of Ampeg) said the mid-60s SB-12 was the best sounding bass amp Ampeg ever built. Keep in mind he was an upright jazz player... but still. I'd call that a pretty good endorsement.

JimmyM · #**679** 01-04-2013, 09:55 AM

#324 AverageWhiteBassist

Everett Hull did love the SB-12, and right before he died, he was working with former Ampeg employee Dennis Kager of Dennis Electronics to reissue it and the Baby Bass. But Everett Hull also had a pretty severe hearing problem due to a beating his father gave him when he was a kid, and he absolutely hated loud music and thought distortion was a travesty, so he likely felt it was more of a gigging amp than the general populace at that time. I'd certainly hit it, though. I've gigged with smaller

stringmaster54 · #**680** 01-04-2013, 10:00 AM

Thanks all for the input on the SB12. The seller wants $1100, and I don't think he'll budge much--it's in a shop and I assume sales tax would also be a part of the equation. It's a couple of hours away so I can't just pop in and make a "take it or leave it" cash offer. It's real clean, but sounds like it's overpriced.