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Discussion in 'Amps and Cabs [BG]' started by JimmyM, May 25, 2008.
What, no "Tonight, on our shoe..."?
Question: how does a '70s B15-N compare to a '60s one? I saw one for a good price locally and am wondering how it compares. I played a '60s one once and was totally blown away.
Here's Dick Cavett's first sign off featuring Bobby Rosengarten and the Orchestra,
Watch closely and you'll see premier jazz bassist George Duviver playing an Ampeg AUB-1 through a shiny new B-15.
Later in the 60’s the girls would screan so loud the Sullivan couldn’t be heard, he would fume and not go on till they turned it down. Basically threatening to turn the car around.
Similar but not quite the same. They have different cabinets, emphasizing lower mids more in the 70’s.
Ask Jimmy, he knows.
The 70's also has the Ultra Hi and Ultra Low switches.
Please forgive my lack of knowledge of electronics. Is it possible to plug bass into a PF50T or PF20T then into a power amp, then into the cabinets? Thanks
Great amps, different vibe. I played many gigs with the B-15N(C) (Double Baffle Reflex) that I still own. I did regularly sit in on a gig where the bassists used a new black B-15N.
So, there is a different sound coming from a Thiel Box vs a Double Baffle reflex. The Thiel might be tighter in the low end, I preffer the Double Baffle, but there’s nothing wrong with the Thiel. The Black B-15 (Helmet Head Logo) is 30 watts and a fixed bias amp, while my Blue Check Vinyl is Cathode Bias and 25 watts. Ultra High and Ultra Low switches are great on the new ones.
Absolutely, though depending on the power amp's inputs, you may need one of those little XLR to 1/4" transformers like Whirlwind sells. But if it has an XLR input, you're good to go with a standard mic cable.
Thank you Jimmy. I knew I could count on you. Much appreciated!
Yes. See the link below...
Ampeg PF-20T to (power) amp
So I keep going to this site, and listening to the Ampeg clone Trip Top kit these folks have come up with.
On the site they claim that you could use a pair of KT88's and increase the power of the amp. Here's what
it says on the site. "The output transformer has 3 Interleaves and heavier gauge winding than originals
and multiple secondary windings (4, 8, 16 ohm support). This is an excellent B15 transformer.
With our over spec’d and non-potted iron, you can optionally run KT88 POWER TUBES increasing the power output.
I've looked up the specs on a pair of KT88's and there are some sites that rate a pair of these babys, giving you
100 Watts. Iis that even feasable, or would the amp just be running to hot to sound like a B-15 with the 88's
Along with the other features of this kit, selectable bias that can be fixed or cathode. etc. I'm kinda
Installing a pair of 88’s will not give you 100W. To achieve this, the amp would have to be redesigned. The plate voltage would have to be bumped up, then there is how they are matched to the output transformer, and the bias.
The amp will deliver a little more power depending on the points listed above. There will be a tonal difference when driven. You’ll get a long life out of the tubes because they are being operated conservatively.
Thanks, David, that's what I wanted to know. I'm really stoked with the improvements I made to the B-15N(C). The JBL-D130 sounds great, in the Double Baffle Enclosure , and I swear that the combination of the NOS Sylvania 6SL7's and
Telefunken 6L6GC'S had tightend up the low end and improved the midrange definition. I'll post some pictures later today. Nothing looks better than that big JBL Dust Cap.
Good to hear that everything came together with the changes.
There are subtal differences in tubes. Sometimes you can make EQ adjustments to compensate but there is differences in how they perform. People notice this more when they are recording or simply sitting and playing. Couple that with your new holy grail speaker or other changes n the response with new caps.
Those of you who have a PF50T: what are some of your favorite settings? I know this depends on a bunch of factors -- personal preference, playing style, the bass you're using, the cab you've paired with it, etc. -- but I'm still curious.
Here are mine so far: gain at 10 o'clock, bass at 2 o'clock, mids and treble flat. Frequency switch on the front at the 3 setting. Attenuator on the back of my 115 cab off.
I have a Fender Aerodyne bass and I use the neck (precision) pickup almost exclusively. I have the other either completely off or on just a tiny bit. I roll about halfway back on the tone knob. This combination of settings gives me a bright, clear tone that isn't piercing. Also, because I use my fingers and tend to play back toward the bridge, I'm not fingerpicking right over the pickup.
Mine are actually similar, maybe a little less bass depending on the room and cab.
The tiptop is a very versatile amp. I've only run kt88s so far, so I can't offer a comparison. I can say I greatly prefer the Mullards to the Gold Lions. The Mullards deliver a much more ampegish crunch. I'm very happy with mine.
Ok here's a few shots of the Ampeg B-15N(C) with the JBL-D130 and the new tubes. I didn't realize how hard it is to photograph a 6SL7 so you can see the Ampeg branding logo.
Looks to be in tip-top shape. Nice clean looking chassis.
Not that it's a problem, but what's the story with the speaker wiring?