Interested In Building 5G9 Or 5E3P Tweed With KT66 & Tremolo

[DougGuy]

Hi fellas, old dog here to swapping tubes and speakers and general amp repairs, but newb to actually building.  I WISH I still had some of the fabulous tremolo amps I formerly owned, Tan '62 AC30, Magnatone 450, etc.

A Facebook friend sent me here, wow I am floored by the level of expertise and knowledge just from reading posts about the various tremolo designs.  He has a 5E3/5E5 hybrid with KT66 tubes and says it sounds very Stones-ish, this is something that would greatly appeal to me to build, but I would like to incorporate the bias shift tremolo like the 5G9 has or the 6G16 (from reading Sluckey's posts, props to you and a few others sir!).

Wanting to avoid common mistakes, I am asking questions first before jumping in, all I have so far is a Classic Tone OT for Bandmaster 40-18088 it has 2.7, 4, and 8ohm taps which I plan to use an old 12" alnico Altec 417-8C speaker which is 8 ohms.

I am aware of Rob Robinette's pages and the various mods and designs, it looks like his 5E3P Proluxe would work then add tremolo circuit, I have just started looking at Hoffman's pages, what direction would you suggest for a Tweed tone, with KT66 and tremolo?  Is it even doable to want a bias shift tremolo with KT66?


I should add I am not super good with schematics, I can figure them out given enough time, but if there's a dummy drawing, yeah I can deal with that.

[sluckey]

I see Rob's layout for his 5E3P Proluxe. But I can't find a schematic. Can you provide the schematic?

[DougGuy]

Hi sluckey, thanks for responding.  If I can figure out how to post images I found these:

[sluckey]

Here you go. Time to learn how to read a schematic.

[DougGuy]

Whoa!  That was slick!  Indeed time to learn to read a schematic!  For an eyelet board, and a layout, I would need more than the eyelet board for a 5e3p now that you have added the trem circuit.  I am thinking a chassis for the 5G9 might work, but before committing to the build, I need to look at Rob's site a bit more and make sure I don't leave anything out either.  There is the question of the NFB control, my buddy that built the 5e3/5e5 said he uses a fixed value so I guess his is not on a pot.  And I know I will have to change some things to use KT66 in the output I think the schematic is drawn for 5881/6l6. 

I haven't yet found the right PT for this, but I am thinking the bolt pattern will likely be bigger than the holes punched in the standard 5g9 chassis because I will need 4amps on the 6.3v tap.

Thank you kindly sluckey!!

[pdf64]

Compared to other 6L6 types, KT66 will require the magnitudes of the signal, bias and tremolo modulation voltages increasing, eg by up to 20%.
Also don’t overlook their additional heater current.

[HotBluePlates]

... a 5E3/5E5 hybrid with KT66 tubes ... but I would like to incorporate the bias shift tremolo ...

If I were to tackle this, I'd go with the original Fender amp with trem:  the 5E9 Tremolux.  Leo Fender literally used this amp's circuit for his patent on tremolo (specifically, applying it at the paraphase inverter to nix pulsing noise).  I once owned a 1955 Tremolux, and can assure you it's an excellent bias-vary trem.

I haven't thought through the paraphase inverter's ability to drive 6L6/KT66 as-drawn.  However, it's much the same as the inverter in the 5C4 Super, which did drive 6L6s.  Good chance it will work as-is, and you know you'll have no problems getting the trem oscillator to have enough grunt to bias-modulate the 12AX7 inverter (which is not-certain with KT66).

Pressing the Easy Button, I'd grab a power transformer, choke and output transformer set for a tweed Super/Pro/Bandmaster, and copy almost everything else from the Tremolux.  The choke will take the place of the 2.5kΩ resistor in the power supply. 

The only hard bits are sourcing a suitable chassis & eyelet board. You can probably forget about having a trem On/Off switch mounted on one of the pots, so add a footswitch or a panel switch as desired.

[66Strat]

If I were to tackle this, I'd go with the original Fender amp with trem:  the 5E9 Tremolux.

The only hard bits are sourcing a suitable chassis & eyelet board. You can probably forget about having a trem On/Off switch mounted on one of the pots, so add a footswitch or a panel switch as desired.

I really like HBP's suggestion.

If one were to move the on/off switch to the Depth control, AES has an Alpha 250k pot with DPDT push/pull switch. Ted Weber used to offer a Tremolux lettering option for his tweed Bandmaster chassis. Treble, Bass, and Presence labels were replaced with Tone, Speed, and Intensity.  In a pinch, one could use a Mojo 6G3 chassis with the added feature of Tone Controls for each channel.

[HotBluePlates]

... If one were to move the on/off switch to the Depth control, AES has an Alpha 250k pot with DPDT push/pull switch. ...

I realized late there are 1MΩ pots with a switch.  Use that in place of one of the 1MΩ resistors-to-ground, and install an actual 2.2MΩ resistor instead of the 2MΩ switched pot.  Easy-peasy.

[DougGuy]

... a 5E3/5E5 hybrid with KT66 tubes ... but I would like to incorporate the bias shift tremolo ...

If I were to tackle this, I'd go with the original Fender amp with trem:  the 5E9 Tremolux.  Leo Fender literally used this amp's circuit for his patent on tremolo (specifically, applying it at the paraphase inverter to nix pulsing noise).  I once owned a 1955 Tremolux, and can assure you it's an excellent bias-vary trem.

I haven't thought through the paraphase inverter's ability to drive 6L6/KT66 as-drawn.  However, it's much the same as the inverter in the 5C4 Super, which did drive 6L6s.  Good chance it will work as-is, and you know you'll have no problems getting the trem oscillator to have enough grunt to bias-modulate the 12AX7 inverter (which is not-certain with KT66).

Pressing the Easy Button, I'd grab a power transformer, choke and output transformer set for a tweed Super/Pro/Bandmaster, and copy almost everything else from the Tremolux.  The choke will take the place of the 2.5kΩ resistor in the power supply. 

The only hard bits are sourcing a suitable chassis & eyelet board. You can probably forget about having a trem On/Off switch mounted on one of the pots, so add a footswitch or a panel switch as desired.

Hi HBP, I was under the impression I might be better off with the fixed bias and the long tailed pair of the 5g9 because I though it might make the bottom end a bit more stout, or cleaner running in front of a pair of kt66, and a high powered, large voice coil alnico 12 like an Altec 417-8C or a JBL. 

I don't care for the small magnet Jensen type speakers where the bottom end is farty or collapses completely.  I like that low E string on a NoCaster type Tele guitar to come through good and strong. 

But hey thanks to all who responded, I'm learning!  All I have so far is a Bandmaster style OT and the Altec driver so I can go either way 5e9 or 5g9.

Edit:  Maybe I spoke too soon, I previously thought the 5g9 preamp was the same as the 5e3 but it isn't.  There is a whole gain stage less in the 5g9 than there is in the 5e9 so maybe the 5e9 is the better way to go if I was going to use a tremolux circuit to start with.  The schematic that sluckey drew is good too, isn't the preamp in that one closer to the 5e3 than the preamp in the 5g9?

[sluckey]

Edit:  Maybe I spoke too soon, I previously thought the 5g9 preamp was the same as the 5e3 but it isn't.  There is a whole gain stage less in the 5g9 than there is in the 5e9 so maybe the 5e9 is the better way to go if I was going to use a tremolux circuit to start with.  The schematic that sluckey drew is good too, isn't the preamp in that one closer to the 5e3 than the preamp in the 5g9?

The 5E3, 5E9, and 5G9 all have the same identical preamp. The difference is the phase inverter. One has a paraphase inverter, one has a cathodyne inverter, and one has a Long Tail Pair inverter. All three phase inverters have roughly the same gain.

The 5E9 does not have the bias vary tremolo that you wanted. I would suggest you forget about the circuit I cobbled together and just build the stock 5G9, but with a bigger PT and OT suitable for KT66s. Hoffman already has an eyelet board for the 5G9 so you don't have to design a layout.

[HotBluePlates]

... The 5E9 does not have the bias vary tremolo that you wanted. ...

I disagree.  The bias it varies is that of the paraphase inverter, at the single cathode resistor shared by both halves.

As a result, it always works regardless of the output tube type.  And we know how much some have struggled with output tube bias-vary trem (though admittedly with larger bias voltages than would probably be used in the proposed circuits).

[DougGuy]

The 5E9 does not have the bias vary tremolo that you wanted. I would suggest you forget about the circuit I cobbled together and just build the stock 5G9, but with a bigger PT and OT suitable for KT66s. Hoffman already has an eyelet board for the 5G9 so you don't have to design a layout.

The OT I have is a CT 40-18088 which is for Bandmaster with 6l6 I assume this will work for kt66.  I have been on the hunt for a PT with 4amps or more of 6.3v.  I thought I had found one for a Bassman but specs show that it doesn't have a 5v tap so back to looking.

[sluckey]

Should be able to find something here. Then go to AES to buy it.

     http://www.hammondmfg.com/

[DougGuy]

Should be able to find something here. Then go to AES to buy it.

     http://www.hammondmfg.com/

Thanks sluckey do I need a choke for this?  I'm thinking it's going to need extra filtering.

I found two PT numbers that might work, which would you choose for this?

P-T273CZ*    VA=159   650V C.T. @ 172ma.    5V @ 3A    6.3V C.T. @ 5A

P-T290CBZ    VA=118   650V C.T. @ 120 ma.    5V @ 3A    6.3V @ 4A << My brain says this is the correct choice but I could be wrong!

[sluckey]

Don't know. Is there one on the schematic?

[DougGuy]

Don't know. Is there one on the schematic?

Ok the Weber proluxe schematic shows PT is T2, W025130, showing 680V AC (330V each leg as annotated by Rob Robinette).

Hmm the Weber PT looks like it might be the better choice, and it's $50 less..

[bmccowan]

Ted Weber used to offer a Tremolux lettering option for his tweed Bandmaster chassis

Weber still offers that chassis: https://tedweber.com/5e7tch/ I've been thinking about getting one as I have an empty Gibson cabinet that it'll fit.
Weber recently redesigned their website. It used to OK; and now its one of the worst designed sites on the Web. WTF?

[DougGuy]

Ted Weber used to offer a Tremolux lettering option for his tweed Bandmaster chassis

Weber still offers that chassis: https://tedweber.com/5e7tch/ I've been thinking about getting one as I have an empty Gibson cabinet that it'll fit.
Weber recently redesigned their website. It used to OK; and now its one of the worst designed sites on the Web. WTF?

I ordered one of these 5e7t chassis and a PT from Weber on the 12th or Feb.  After several emails, and asking them 3 times if it had been shipped, I STILL do not have any shipping or tracking info.  Seems they held back for a week from shipping a closed and paid for order b/c I had left a choke in my shopping cart.  WTH?  After a few days they email me asking about it.  WHAT IN THE WORLD are they thinking?  And the email has to get BCC so the guys who do the shipping can see it?  It ain't the website bud, it's the WHOLE SHOW they got going on there.

Hope I am not buying parts in the meantime and then they finally tell me they don't ave this item in stock, they sold and shipped the last one while they were sitting on their thumbs with my already paid for order.  And every email asks me to tell fellow players about them.  REEEEEALLY???

[shooter]

And every email asks me to tell fellow players about them.

spent 1:45 on hold with H&R about their SW, constant bot-voiced "how wonderful we are"
3 minutes actual human, and human asked the same thing "would you like to take a survey..."
I said you would get fired if i answered the survey, so no thanks

[DougGuy]

And every email asks me to tell fellow players about them.  REEEEEALLY???

Well, I got their attention, after 12 days and several emails, my order got "shuffled under some speakers" but they shipped it and sent a tracking number, then gave me a 15% refund on my order for the trouble and aggravation so, at least they care..  Maybe I will have a Tremolux/kt66 after all.