Jess Oliver lives on through The AMPEG PORTAFLEX CLUB - now up to lucky 7! - Page 5

beans-on-toast · #81 02-20-2012, 12:37 AM

That's interesting Clint.

I've seen these stickers on amps from as far back as the 50's.

The department (ladbs.org) still issues them to manufacturers, at least for building related products.

I believe that the stamped number is the manufacturers license number for a particular product. I tried searching for my number on the Building and Safety web site but didn't find anything.

I figured that the Underwriters Laboratories safety approval would supersede the LA regulations and that there is no longer a need for city approval. But UL was around in the 1984 when your sticker was applied. California always seems to have stricter regulations than the rest of the US.

FenderAmpeg · #82 02-20-2012, 06:04 AM

Quote:

Originally Posted by beans-on-toast

California always seems to have stricter regulations than the rest of the US.

We have all the fun.... CalOSHA, Regional Water Quailty Control Board, South Coast Air Quality Management District........we get all the help we can handle......

John D · #83 02-20-2012, 07:22 AM

Quote:

Originally Posted by beans-on-toast

I figured that the Underwriters Laboratories safety approval would supersede the LA regulations and that there is no longer a need for city approval.

But David...the city can't charge a fee for the UL stamp.

beans-on-toast · #84 02-20-2012, 09:14 AM

Maybe they can charge to have a civil servant inspect the amp to ensure that the UL certification label is in place.

ace14 · #85 02-20-2012, 11:56 AM

I was wondering what kind of tubes people are using, especially for the rectifier tube: is NOS really better than new or is it just a hype?

**ddbassGA** · #86 02-20-2012, 02:35 PM

Quote:

Originally Posted by ace14

I was wondering what kind of tubes people are using, especially for the rectifier tube: is NOS really better than new or is it just a hype?

So they say. I use JJ rectifiers with good luck. I understand those are patterned after the Mullard, which is the gold standard. I can't see spending $80-100 for an NOS Mullard 5AR4.

I do use vintage preamp tubes (RCA 5691 or JAN versions of 6SL7GT, and vintage US or Amperex Bugleboy 12AX7's). And I've lucked into a sweet stash of vintage power tubes (6L6 and 7027) but can't afford the NOS GE 6550's I want for my SVT.

stiles72 · #87 02-20-2012, 02:50 PM

I think NOS RCA's or Sylvanias really do sound the best. But when it comes to modern tubes, to be honest, I've had good luck with plain old Sovteks for both preamp and power tubes.

beans-on-toast · #88 02-20-2012, 03:06 PM

Both the most recent Sovtek and JJ make a nice 5AR4 rectifier which is based on Mullard designs. If you want to spend more for what they used originally, get a Mullard.

One big advantage of NOS tubes is the reliability and long life. There are subtle differences in tone over new tubes. Since I'm always chasing tone, those subtle differences are important to me. But it comes at a higher price. I run RCA power tubes, Sylvania pre-amp tubes, and (when I use a tube) a Mullard rectifier tube in my B-15.

I buy used tubes at Hamfests to check out different types at a very low cost.

David

Farfetched · #89 02-20-2012, 04:03 PM

Is there a reason why most of the 5ar4 s out there are made in GB (i'm assuming mullards)? Even a great number of GE and RCA were relabeled mullards....

beans-on-toast · #90 02-20-2012, 04:56 PM

Even RCA used to buy from Mullard. I can only guess that nobody did it better for the money.

In the 50's and 60's the UK pound was about 2.80US. In 1960 the 5AR4 tube listed for $4.80. In 1978 the list price was $6, dealer price was $4.80 from Ampeg. It was probably cost effective to import them and support the post war UK economy. Countries offered incentives to help the UK out at that time. Diodes were slated to replace the tubes so they were probably scaling back production elsewhere. Just conjecture on my part.

spellcaster · #91 02-20-2012, 09:17 PM

Finally found myself a 65 B15 and love it! The JJ 6L6GC's seem a bit microphonic so I've started looking into the vintage tube variations. Has anyone used the military spec 7581A?

beans-on-toast · #92 02-20-2012, 09:32 PM

Yes the 7581A is a great sounding tube with good headroom. They tend to be quite expensive with the price driven up by the hi-fi community.

You have to be careful, there have been some fakes of this tube turning up. They take 6L6GC tubes and label them as 7581A's to try to cash in.

spellcaster · #93 02-20-2012, 09:44 PM

Good to know about the fakes. Thanks! Your right about the prices. I was watching an auction earlier and they certainly ended much higher then expected. The quest continues...

lance_randy · #94 02-21-2012, 07:13 AM

Oh my God, the B-15...what can I say? I have a '63 B-15 and it is absolutely the sweetest, most wonderful sounding bass amp I have ever heard/played through in my entire life! The only thing I don't like about, is that it doesn't do loud. I hate moving it too, so it stays at home where it is safe

I just can't say enough good things about the B-15, it is truly a magic piece of gear, without it I would be ruined! I found my sound with this guy, a '77 Stingray bass with dead-ish rotosounds, eq dialed all the way down on the bass, maybe a little bit of bass, depending on the situation, and the bass knob on the amp at around 2'o clock. WOW! This amp really responds to how you play. I dig in a bit, and I get this great grungey midrangey kind of tone, with just the perfect amount of compression. (a bit like Jeff Berlins sound on the Bruford album "gradually going tornado" but a musicman version, if that makes sense). Play a bit lighter, and it's Jamerson, Chuck Rainey sounding (musicman version). It has this wonderful three dimensional thickness to it, that I have never heard from any other amp (an old SVT comes the closest). Honestly, every other rig I have put against the B-15, just sounds anemic in comparison, none of them have that 3-D 'thickness' and grunge factor that the B-15 has. Sometimes I'll fire up my Eden rig, and feel like I have a good sound going...and then I plug into the B-15. Suddenly the Eden stack sounds tiny and thin in comparison. Want to record? Throw a mic in front of it, perfect every time! I honestly don't know what I would do without the B-15, it is just that great!

billyfalconer · #95 02-21-2012, 08:00 AM

So what are the years for NOS tubes for these amps? The tubes have been manufactured almost continuously, along with the amps, from the early 60s to the present. What year is the break point for NOS vs modern?

beans-on-toast · #96 02-21-2012, 08:26 AM

I consider the good NOS tubes to be those manufactured in North America, Japan, or Europe. Typically they were manufactured from the 1920's into the 1980's and the companies are no longer producing these tubes.

These tubes sound good, last long, and are reliable.

dangorange · #97 02-21-2012, 09:37 AM

Hi, sorry if this is a often asked question, I have a 1966 B15N with the 30w fixed bias circuit and want to replace the original tubes that came with the amp, partially to see how fresh tubes would sound.

I bought a set from fliptops and am wondering if it's ok to simply pull the old ones and replace without checking voltages etc. I know it's best to have it checkout out when replacing tubes, especially the power tubes but I do not have the necessary equipment on hand and the set I bought has matched pair of 6L6GC.

I've biased my Orange AD200b before, but I had to borrow a friend's bias probe and that amp has a trim pot, I've also done a bit of troubleshooting on other tube amps so I know to discharge the power caps so I don't kill myself!

My guitarist is an amp tech and since my experience is limited with working on amps, I'm going to have him give my B15N a good look over later this week, I just want to see if I hear a difference with the new tubes

I can wait if it's a bad idea, though....

stiles72 · #98 02-21-2012, 11:12 AM

My understanding is that B15's are "plug and play" when it comes to replacing tubes. As long as you are using a good matched set of 6L6GC's, you should be good to go.

christw · #99 02-21-2012, 11:28 AM

dangorange, what are your stock power tubes? Mine had (original?) black plate RCA 6L6GC among others which are worth quite a bit hiding under the tube cage.

dangorange · #**100** 02-21-2012, 12:14 PM

Quote:

Originally Posted by christw

dangorange, what are your stock power tubes? Mine had (original?) black plate RCA 6L6GC among others which are worth quite a bit hiding under the tube cage.

They're Sylvania's for both the power tubes and the pre's. I assume they're original because of Ampeg being written on them, but I guess they could be older replacements. I was told they were original though.