Tube Amps / Music Electronics
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|11/29/2003 1:37 AM|
|Bob Arbogast||Anyone ever build a 5E3 Plus?|
I'm pondering a 2x12 5E3 with a GZ34 and a pair of cathode biased 6L6's. Part of the build would include beefed up transformers (e.g., David Allen's 180mA, 650Vct Deluxe PT and paper-interleaved 4-/8-ohm Vibrolux OT).
Anyone ever made such a beast?
I would consider a 4 x 6V6 build, but a chassis is not readily available.
|11/29/2003 5:02 AM|
It sounds like you want to build a higher power tweed deluxe and I would make the following suggestion. Convert the standard 5E3 circuit to 6L6's and use the two speakers you desire for more spl's. Bruce is the guy for the 6L6 deluxe amp setup. He has helped me tremendously on a coversion I am doing to a standard 6V6 deluxe. He suggests a 5AR4 or a 5V4GT rectifier to increase the plate voltage and therefore the output power as well as the following changes to the standard 5E3 circuit.
1.)The dropping resistor between the first filter caps needs to be replaced from 5k1-2watt to 2k7-2watt. You can go as low as 1k-2watt to get the preamp voltages up to where you get more clean sound without distortion.
2.)The two power tube's cathode biasing resistor, 270-5watt, needs to be changed to a 270-10watt.
3.)Install a 1k-2watt screen resistor on each power tube socket and rewire them like a 30-50watt black face Fender amp. To clarify this: Look at a Super Reverb AB763 schematic/layout. Use 470-1w to 1k5-2w values, soldered on the power tube sockets (lug 6 to 4) for the screen resistors with the screen supply B+ fed at lug 6 and. The 1k5 ohm grid stopper is moved and soldered in from lug 1 to 5. Grid (signal lead) wire is now attached to lug 1. Remove and lower the 5k ohm resistor, (voltage dropping node between the first two filter caps) to 2k2 or 2k7 ohms. This 2k2-2k7 ohm resistor would be in the same location as the choke in the Super reverb.
4.)Using a little bigger Output Transformer(25-30watt blues Jr. trannie) will get you an additional 5 to 7 watts. Bruce has them.
5.)Using .022 coupling caps to the volume controls
(in place of the stock .1uf caps) and 4.7uf cathode bypass caps on the preamp tubes will net you a cleaner tone too, but using anything less than .047 caps to the power tubes seems to wreck the tweed tone too much.
By the way, the Blues Jr. Output Transformer is rated about 25-30 watts and has a 4 and 8 ohm secondary so it can still be used with 6V6s and 6L6's. If you want the 6V6s, you'd connect the 8 ohm speaker to the 4 ohm wire to get the primary impeadance back up where 6V6s run. With the 6L6's you use the 8 ohm secondary wire. This can be setup with a SPDT toggle for switching between tubes.
With this configuration you could have:
a.) The 5E3 with 6V6's on the 8 ohm speaker for 12-15 watts on the 4 ohm secondary setting.
b.) The 5E3 with the 6L6's on the 8 ohm speaker for around 30 watts on the 8 ohm secondary setting.
c.)The 5E3 with 6L6's on the 8 ohm speaker and a 8 ohm extension speaker for a total load of 4 ohms at around 30 watts on the 4 ohm secondary setting.
All of this knowledge is from Bruce so thanks go to him. I hope this helps you Bob. Bruce correct me if I got anything wrong.
|Book Of The Day||
The Ultimate Tone, Volume III by Kevin O'Connor
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|11/29/2003 5:15 AM|
"By the way, the Blues Jr. Output Transformer is rated about 25-30 watts and has a 4 and 8 ohm secondary so it can still be used with 6V6s and 6L6's".
I think you mean the Blues Deluxe OT, not the Blues Jr.
|11/29/2003 2:22 PM|
||I have a Mike Clark version|
A few years back i got bit by the Tweed thang. However, at the time I was "tuned" to blackface and musicman voicings. I played a Clark Beaufort and thought it was great but if it only had a little more headroom, a little reverb etc. Not that these things are not desireable, its just that I had not really appreciated/learned of the sweetness in the stock 5E3.
So, Mike Clark and I drew up some plans for a 5E3 conversion with the following changes to hopefully meet my expections:
Tubes: NOS 6L6 with AR4 rectifier
Cabinet: slightly larger, pine with tweed
Speakers: 2 x 10 Weber Blue Pups
Upgraded PT: we used the 16 ohms tap to utilize all the windings.
3 knob reverb unit
The results are an amp that is just majestic in tone and feel. I can honestly tell you that the old BFVR I had could not touch this amp on tactile response, grind or vibe. I still loved that spank of the BFVR but 9 out of 10 times I plugged into the 6L6 5E3 unit. Just a better sound.
I wish I could tell you what other things he did to the amp but I am not a tech guy. I wish someone lived near me to help me work on a project and get me on my way.
What I can tell you is that if you need to push the envelope on the 5E3, you will be pleased.
|11/29/2003 2:38 PM|
|bnwitt||Re: Anyone ever build a 5E3 Plus?|
I did indeed mean Blues Deluxe. Sorry for the error.
|12/1/2003 2:50 AM|
I just finished mine with a couple minor differences. I went with a 2 X 10 configuration cuz thats what I had layin around.
I used a Super Reverb type PT, and a Bandmaster type OT. I got them both from Sovtek. I also added 16uf to the first stage of power filtering. Everything else remained the same.
This thing rocks! So much so that I decided to make another, and run in stereo.
The amp even has a useable stage volume, where a 6V6 driven 5E3 sometimes has a problem keeping up. But I guess that depends on the kinda band your playin with.
As a side note, I used Paper and oil caps for all the signal caps (except the small cap for the tone circuit where I used a mica) and in a side by side comparison to the same thing I built with orange drops, well, the orange drops were replaced immediately. I used the Sequa's that the dude at Angela sells. They still arent cheap, but I think they were worth it.
I've also built the 4 X 6V6, but to the 5F8A circuit. The 6L6 5E3 breaks up earlier as one would expect, and doesnt get as loud as the 4 X 6V6 5F8A.
Hope this helps
|12/1/2003 4:01 AM|
|Bob Arbogast||Thanks and a question|
Thanks for the info. Have you compared your 6L6 5E3 to a "normal" 5E3 in terms of the amount of drive and compression? My one concern in building a 6L6 version is that the 5E3 preamp won't drive 6L6's to the same degree that it drives 6V6's
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