Saturday, January 26, 2013

1962 Premier Twin 8 vs 1964 Marvel Amp

Two early 60's amp made in NYC by Multivox.  They share similar circuits, with 7591A power tubes and 12AX7 preamp tubes.  The Twin 8 has two 8-inch speakers while the Marvel amp has a single 6-inch speaker.  They both make about 6 watts of power.

Both amps have been worked on by Bruce Collins at Mission Amps.  Both had grounded power cords installed and worn components replaced.  Two tone caps were changed on the Twin 8.

Friday, January 18, 2013

Nice Tone! Greg Heumann's K-Zoo Amp

This video was sent to me by a friend.  This is an old Kalamazoo amp  retrofitted by Greg Heumann at Blows Me Away Productions.  Very nice.

Tuesday, January 15, 2013

My Latest Project - Premier Twin 8 amp

The Premier Twin 8 is an icon of vintage harp tone, known for it's colorful crunchy tone.  It arrived yesterday and needs a bit of work.  It still has the flimsy power cord and 2-prong plug.  The pilot lamp is burned out.  And, it needs a general going-over by a good tech.

The power tube (7591) and the rectifier look to be original, as do all the tone caps.  The preamp tubes are Tung Sol 12AX7.  The layout and tone are similar to the vintage Marvel amp I rehabbed recently.  They were both made by Multivox in the early 60s.

It is a small bugger.  I will put up a photo later with something to reference its size.

I'll report back as this project progresses.  This should be fun!

(That's a regular Mississippi Saxophone harp case next to the Twin 8.)

First test recording

Monday, January 14, 2013

Perfect Amp Tone?

In this video Nic Clark is playing my Mission Chicago 32-20 amp, with zero effects, not even delay.  To my ear this is perfect amp tone:  Warm and full with a bit of crunch.  It gets some sag and sings with overtones, although that does not come across as well in the video as it did live.

The tone is not shrill and the grit is not ratty or overdone.  It is not boxy or nasal or muffled.  Perfect.

When I say "perfect" I mean it is my ideal harp tone.  It is what I had in my head when I was helping to design and develop this amp.  I know full well that amp tone is subjective and there is no such thing as perfect tone, but if you ever wondered what perfect tone means to me, this is it.

Thursday, January 3, 2013

Blues Harp PA Test

Goofing around with gear; trying to get a gritty sound though the PA.

I set up my PA and played through it using a Shure SM57 mic. The PA is a Mackie 808, the PA we use at clubs that do not have a sound system. I used Mackie C200 speakers.

What I listened for was that slight tearing on the front edge of percussive notes you hear with a nice tube amp. That is the "grit." So I just played the same things over and over and listened.

First I played directly into the PA with everything set flat and the channel trimmed so it was not clipping except on the loudest transients. The tone was as you might imagine: Pretty dry.

Next I cranked the channel trim all the way up and rolled back the master volume. Better, but still not very tube ampish. It distorted but not with the same nice sound you get from a good harp amp.

Then I used a Presonus Tube-Pre between the mic and the PA. I cranked the Drive control and rolled back the Gain control on the Presonus, and backed off the channel trim on the PA a bit. It still clipped the PA channel most of the time.

The preamp did give a bit of that sound. The sound does not have all the moving parts you hear in good tube amps, but if what you want is grit it did have some of that. I thought it sounded pretty good.

I don't think they make the Presonus Tube-Pre any more, but you can get the same effect from an ART Studio Mic Preamp which sells for less than $30.  I've seen Kim Wilson use it.