Friday, October 28, 2011

Bassman RI Harp Amp Project - Update

Here is the latest on the Bassman RI project:

-From right to left the preamp tubes are RCA 12AY7, and two JAN Philips 5751.

-The power tubes are Tung Sol new production 6L6.

-The rectifier tube is a JAN GE 5R4 brown base.

Bruce Collins at Mission Amps installed adjustable bias pots, biasing the power tubes rather cold. He also repaired a faulty tube socket under one of the power tubes. Other than that the circuits remain stock.

The speakers are two Weber 10A125-O on top, an Eminence Lil' Buddy hemp cone speaker on the lower left, and one of the original alnico blue speakers on the lower right.

We tried many different combinations of tubes in all the sockets before arriving at this configuration, which sounded best. We both like a big fat organic tone, with a punchy low end and some sparkle without being edgy. I like a harp amp to sound wide.

This amp sounds good. In Bruce's shop I could get it to 5 on the volume before it started to ring, and the sound was big with a nice warm tone. It is not as naturally crunchy as my Chicago 32-20 amp but it has it's own set of virtues. That old Coke-bottle full-wave rectifier gives it a very cool sag, and the alnico Webers compress nicely as you put some pressure on the amp. It makes about 40 watts in this configuration and is quite loud. It weighs 62 pounds.

I plan to leave it like this for a while, and I'm looking forward to flogging it at a gig we are playing Saturday night Oct 29 for a Halloween Party at a country club. I promise... sound samples will be coming soon.

Saturday, October 15, 2011

Harp Amp Project - Fender Bassman RI

Today I bought a rather well used early Fender Bassman Reissue amp, which dates from April of 1991 by the production code. The amp has a tube rectifier (not solid state) and the original alnico blue speakers, which are re-branded Eminence 1028s. I paid $500.

The amp was playable when I got it home, but the tone was shrill and it had intermittent problems. A couple of the tubes were bad, so I replaced the 5881 power tubes with some Tung Sol new production tubes I had on hand, and swapped in a 5AR4 Sovtek rectifier. For now the preamp tube is an NOS JAN Philips 5751 and the 2nd gain stage tube is a vintage GE 12AY7. The phase inverter is a 12AX7.

I swapped out 3 of the 4 speakers: On top there is a pair of Weber 10A125-O speakers, and on the bottom is an Eminence Lil' Buddy ceramic speaker and one of the original alnico blues.

So far it sounds pretty good. I'm sure it will sound a heck of a lot better after I get it biased and tuned by Bruce Collins at Mission Amps in Denver. Since I tinker with amps a lot I had all the parts I used today laying around in my amp room, so there has been zero added expense on the amp so far. I was looking around for an old Bassman RI, partly because I recognized I already had a lot of the components I would need for the project.

I'll put up sound samples later. I plan to take the amp to a blues jam tomorrow night to see how it performs as it is now. I'll keep you posted.


Wednesday, October 12, 2011

New Cable

New cable: Fender "Vintage Voltage." My trusty old Planet Waves cable I've been using for nearly 10 years is starting to get noisy. I think I've stepped on it too many times...


(I've gigged with this cable and it sounds great. Even my guitar player noticed. My old Planet Waves cable must have been farther gone than I knew.)

My purchase of the Fender Vintage Voltage cable generated some discussion on Facebook. Chris Richards, among others, said the fabric covering of retro cables rubs against the “rubber” inner sheath and creates a small electrical charge that makes the cable noisy and raises its capacitance, changing its tone.

I’m not so sure. I’ve heard that before but have never seen definitive evidence to support it. Chuck Gurney is a very well-known custom harp microphone maker who also makes and sells cables – all of them cloth covered.

I found a web page from Ovni Labs comparing and testing several instrument cables. Their top three picks were all cloth covered.

So what’s the deal? Is the story about cloth cables being inferior just an old urban legend? Chris makes and sells fine custom cables that are not cloth covered, so he may have a bit of an agenda here. I’d like to know what you think.

Monday, October 10, 2011

Walkin' Blues at Ziggies Blues Jam

Devin from L.A. dropped into the jam and blew some manic harp. Great energy. Devin is playing through a custom bullet mic with Shure CM element into a Mission Chicago 32-20 amp.

Steve Mignano on guitar, David Brenowitz on drums, Mike Wysocki on bass.

Thursday, October 6, 2011

Coming up on Saturday

Ronnie Shellist will be playing blues harp with the headliners, Boa & The Constrictors. My band precedes them at 9:00pm. Should be a hell of a show...

Sunday, October 2, 2011

RJ Mischo Endorses Harpgear Amps

Good move for Brian Purdy at Harpgear. RJ Mischo is a great player and a tremendous ambassador for blues harp in general.

The amp pictured is an HG50 1210 with a new look.