Friday, October 24, 2008

Weber 5F2H Harp Amp

Here is my most recent acquisition: A Weber 5F2H Harp Amp. This amp is sold as a kit by Ted Weber, but this example is already professionally built with a few interesting upgrades.

The 5F2H is basically a clone of a 1950s Fender Tweed Princeton amp that has been hot-rodded for harp. Instead of 5 watts from a single 6V6 power tube, the 5F2H produces 15 watts from a KT66 tube (one of the 6L6 family) and a bigger output transformer. It is a single-ended Class A tone monster.

This amp differs from the stock Weber kit in several ways. The input tube is a beautiful NOS RCA Blackplate 5751, my all-time favorite preamp tube for harp. The rectifier is a solid state Weber Copper Cap WZ34 in place of the glass tube. These Copper Caps have all the sag and tone of the tube, but are much quieter and will last the life of the amp.

The biggest upgrade is the cabinet, a 5E3 (Fender Tweed Deluxe) with a 12-inch speaker. The Pro Junior is pictured next to the 5F2H for size reference. Check out that snakeskin tolex. I’m not sure I’m cool enough for that…

When I got the amp it had a nice old Mojotone MP12R alnico speaker, which is a very good guitar speaker; a knockoff of the Jensen vintage alnicos. However, I don’t care for the sound of the Jensen alnico as the only speaker in a harp amp. They can sound great combined with other speakers in a multi-speaker cab, but by themselves they sound too bright and harsh for my tastes. I’ve removed the speaker (it is for sale) and I’ve ordered a Weber 12F125-O with the H dustcap.

The amp cab, speaker, and chassis had a few alignment issues when I got it (the KT66 tube touched the speaker magnet, for example) but the switch to the ceramic speaker will help, and I’ll tweak things when I re-assemble the amp. Also, I need to devise a way to brace the chassis from the bottom or sides. It is too heavy to be held in place only by two bolts in the top of the amp.

I didn’t play it much before tearing it apart, but I did do an A-B comparison with my project Fender Pro Junior amp. They seemed to have about the same volume; the 5F2H was a little fuller, it made the Pro Jr sound a bit boxy. I’m looking forward to putting it all carefully back together with an excellent harp speaker and thrashing it out. I’ll post a full review with sound clips next week.

UPDATE 11/06/08: Here is a shot of the reassembled amp with the Weber 12F125-O speaker. You’ll notice I swapped a coke-bottle 5V4 tube for the Copper Cap solid-state rectifier. I also added finish washers to the mounting screw on both back panels, and lock washers to the chassis mounting bolts. Everything is tight and squared away now.

The ceramic speaker gave me a little more room for the KT66 tube. The mounting holes for the chassis are slotted, so I slid it as far as I could toward the baffle. When I got the amp the big tube was crammed between the alnico magnet and the back panel, actually touching both. Now it runs free…

This amp is dead quiet. Even at full volume you don’t hear any tube hash. It’s pretty heavy for a small amp at 32.2 pounds. The big output iron and the ceramic speaker make it hefty.

I’ll post sound clips and a full review soon.

Sunday, October 12, 2008

Open- or Closed-Back Cabs for Blues Harp?

You may have noticed that I have a propensity to test conventional ideas. When I decided I needed a speaker cab I went with a closed –back design, while almost all harp players seem to prefer an open back cab when using separate cabs and heads.

I liked the way some closed-back cabs sounded with guitar: Dark and THUMP! I wanted to try that with harp, so I ordered a 2x10 closed back cab from Avatar, thinking I could saw off part of the back panel to convert to a semi open-back configuration if it didn’t work out.

All those cool old tube combination amps harp players use are semi open-back for two reasons: Efficiency and air circulation. Open-back cabs can sound louder than closed unvented cabs, and those tubes get HOT and need airflow.

I’ve played the closed back cab for several months and like the low end, but to my ear it sounded kind of muddy, so I finally got around to removing the back panel and running it across a table saw, cutting off the bottom seven inches.

Now it sounds great! As expected, the cab instantly sounded more lively and open; more musically nuanced, more dynamic. I drove it with my Masco ME-18, which is kind of a darker-sounding harp amp, and also with a Fender Pro Junior and a Fender Champ. They all sounded good, particularly the Champ.

I miss the deep grind I could get with the closed cab when bending a 2-hole draw reed with a tight cup on a lower-tuned harp, but the open cab is more versatile and efficient. So, there are good reasons why some wisdom becomes conventional. Semi open-back cabs sound better.

But if I change my mind I can always put that bottom panel back on the cab and get deep and dark again…

TEST NOTES: The drivers in the cab as I write this are a Weber Sig 10 alnico with smooth cone and a Jensen Mod 10 ceramic. I have a Weber Beam Blocker on the Jensen.

Thursday, October 2, 2008

Ted Weber

I first encountered Weber speakers several years ago when my guitar buddies started raving about them. I was skeptical. Weber speakers just didn’t do it for me.

But when I was later working on my
silverface Champ amp project – creating the ultimate SF Champ for harp – I found that Weber’s 10A125-O speaker was the best sounding blues harp speaker on earth. And I had tried nearly all of ‘em…

I tried the
Weber Beam Blockers, and again they delivered exactly what they promised. The Beam Blockers are now my secret weapon in harp amps.

I found the inexpensive
Weber Signature ceramic 10-inch speaker to be a very good blues harp speaker when I was working on my Fender Pro Junior harp amp project.

I played
Weber’s 5F2H harp amp kit at a blues jam and I thought it was one of the best-sounding small harp amps I’d every heard -- no doubt due in large part to its use of the aforementioned 10A125-O speaker.

So, Ted Weber was developing a pretty damn good batting average with the
Blues Harp Amps Blog. I can be a harsh critic when products don’t deliver the goods, or when they just sound nasty with blues harp. When I decided to try Weber’s Copper Cap solid state rectifier I half expected it to suck. Nobody bats 1.000, do they?

I ordered the 5Y3 version because the rectifier tube in one of my amps was getting noisy, and it gave me a good excuse to try out Weber’s $22 alternative. The bottom line is the Weber Copper Cap rectifier is another great product from Ted, delivering exceptional performance and value. After it arrived and I futzed with it a bit, I ordered another for a second amp. I’ll post a more comprehensive review of the Copper Cap later, but suffice it to say I am very impressed with Ted Weber and his line of products.

UPDATE: FedEx lost the second WY3GT Copper Cap I ordered (it was reported on the FedEx website as delivered but I never got it). Weber shipped a new one as soon as I alerted them about the lost shipment. Good people...