7C5 Idea

[DummyLoad]

I have used 40uF with 5Y3GT in several applications without any issues, but note I was only using NOS rectifiers. The 32uF/32uF 500V F&T or J&J would be a good choice for this application.

--Pete

[kagliostro]

As I told there were AC30 that used that arrangement but in later models VOX swapped to a more usual "in series" arrangement

If there is an advantage in the use of the "parallel" arrangement is that the math to calculate the resistor value of the filter Is semplified as you know for each filter the input voltage

Your sperimentation  Is interesting and I'm interested to know your opinion on the result

Franco

[dwinstonwood]

Thanks Pete. I'll also be using a NOS 5Y3GT. 

Thanks Franco, I'll be posting results for sure!

Added updated drawings with larger filter caps and board drawings now on 8.5'' x 11" sheet:

[dwinstonwood]

Well... this project is on indefinite hold. I was getting ready to order parts and started thinking about the fact that none of the amps I've build have reverb, and the only two that have tremolo use the bias-wiggle type.

So, I'm going to build a Revibe instead.  I'll get a lot more use of that than building yet another amp.

Thanks for all the input, help and suggestions on this 7C5 project. I did complete the drawings, and I fixed the pot wiring in the layout - they were wired backwards in the previous drawing. 

I'm sure I'll start a new thread since I know I'll have questions...

David

[kagliostro]

Ciao Dwinstonwood

What about a Revibe/Herzog/Mini Amp ? 

Franco


p.s.: For the Revibe give a look to the project of our friend Sluckey

[Willabe]

The revibe in not a bias wiggle tremolo. And it doesn't sound like a trem.

It's the Fender brown face amps trem/vibe. Has a different sound then trem or vibrato. Kinda in the middle? You really need to hear some clips of it if you haven't yet, before you build it. Guys argue over if it's just a trem or is a pitch shift vibrato.

Some love it, sluckey loves his. I'd build sluckey's if I built 1. All his documentation including layout and schematic drawings are below;

https://www.sluckeyamps.com/revibe/revibe.htm

[dwinstonwood]

The revibe in not a bias wiggle tremolo...

Hi Willabe, yes I understand that the ReVibe has the 6G12 trem/vibe circuit. What I meant to say above was that the only two amps I've built with tremolo both have the bias-wiggle type, e.g., 6G3 Deluxe.  I edited my post to clear up any confusion.

[kagliostro]

Some time ago I had the idea to mix a Revibe (maintaining the reverb section) with Merlin's Vibrotron

https://ampgarage.com/forum/viewtopic.php?t=33565#p415161

But so far I haven't made it yet, even though it's still on my wish list

Franco

[dwinstonwood]

Thanks for that Franco! So, that's the circuit that Vox borrowed from Wurlizter?

[kagliostro]

Yes, that it is, don't remember if there are minor changes, on my PC I saved also some amazing samples, but at the moment it is broken

Franco


p.s.: note that Merlin used a 150V PT because he had it under hands, I think also a higher B+ can be used but don't know in wich way it will affect the tone

[murrayatuptown]

I bought a 7N7 cheap on eBay, then a 14N7 from same seller, ordered 10 Loctal sockets from China, then bought a lot of 7C5's, then enough Loctal sockets to feel safe(same number of sockets as tubes)...and realized the 7C5's were more used than NOS (there ARE some). I weeded out one that rattled when rotated, and one with corroded pins.

M

[dwinstonwood]

Thanks Murray. I've only been buying so called "NOS" tubes from sellers with 1K+ sales and over 98% positive feedback, free shipping and a free return policy. But that doesn't mean those buyers always knew what they got. It's possible that a never-used tube could have its silk screening rubbed off, but if it's been out of the box enough times for that to happen, then who knows if it's seen use or not? The good thing is that buying a "NOS" 6AT6 for $9 with free shipping from a seller as described above is not a big risk. That's a Chick-fil-A sandwich in the neighborhood where I work.

So, I've been listening to a bunch of 6G1X harmonic tremolo videos on YouTube today (at work). I have to have it. 
Not mention, Fender tube-driven spring reverb. I'm surprised it's taken me this long to make this decision.

[Willabe]

So, I've been listening to a bunch of 6G1X harmonic tremolo videos on YouTube today (at work). I have to have it.  Not mention, Fender tube-driven spring reverb.

Now listen to the new Magnatone pitch shift vibrato, make sure it's the stereo vibrato. The mono's very good, but the stereo is just off the hook! It has this watery fluter sound from the sound going back and forth from 12" to 12" speakers.   

Only thing that might be better is a real Leslie, but not a 2 speed Leslie, a variable speed Leslie. Yes they have those, I have 1. Speed is controlled with an expression pedal. The in between speeds sound much better for guitar than the standard 2 speeds that a Lesli has. 

[dwinstonwood]

Thanks Willabe. I found this Brett Kingman video. That's an unbelievable effect. 

I've always wanted to play through a Leslie. Listening to those Harrison recordings when I was a kid was what made me want to play the guitar. That sound is burned into my psyche. In the early 80's we would always go to see local Lindy Fralin and the Bopcats whenever they played. They had a Leslie cabinet; no other band in town did.

[kagliostro]

Real Leslie or .....

https://sluckeyamps.com/leslie/leslie.htm

this will be something you can duplicate

but, for  those who like to experiment the difficult way

(in procuring the components)

https://sluckeyamps.com/warbler/warbler.htm

Franco

[Willabe]

I found this Brett Kingman video. That's an unbelievable effect. 

Bahhh, a Tele! No,no,no,no. Tele's to thin to hear the lushness of the vibrato.

Plug a Strat in! (Or buck clean.) You can't hear the watery flutter of the 2 speakers with the sound flipping back and forth on the video. He'd have to record it with 2 mics.

Lonnie Mac started the Maggie vibrato. And the 'whammy bar was named after Lonnie using a vibrato bar on his flying V in this song. After Wham came out everybody started calling it a 'wammy' bar. 

Wham;

i=nUeQUus8EbP9tQi7

Slow blues with the Maggie vibrato. Stop;

i=BZSI9y_wgK4-ioHO

He has many other songs with the Maggie vibe on it, it was his signature sound.

[Willabe]

Listening to those Harrison recordings when I was a kid was what made me want to play the guitar.

When we 1st heard Badge by Cream my buddies and I got hooked. But a Leslie was expensive AND heavy!     It's George on the bridge playing through the Leslie on Badge.

The 1st Leslie's only had 1 speed, later they went to 2, slow/fast. The thing with buying an old used Leslie is shipping.    I happen to find 1 a few years ago in about 8 out of 10 condition and it was only a few miles from me! The seller even dropped it off at my house!     

It was a single speed but I knew that there's a multi speed kit mod for those that uses an expression pedal. I installed the kit and with the pedal you can sweep the speed until you find what you like. 

With a Hammond the 2 stock speeds sound fine, but with a guitar there's different speeds in between the slow/fast stock speeds that sound way better.

[Willabe]

The old Maggies weren't very road worthy.

Lonnie later used the Maggie preamp fed into a Fender BF Bandmaster head and separate speaker cab, a piggy back Fender.

Yes, I open up the head on mine, looks very strong to me. Their web site says 56lbs, I don't believe it, feels like more!     So I bought the piggy back model, costs more, but I can move it. 

That used to be easy to move, but I'm older now.   

[glass54]

Hi dw,
From reply 44

Thanks Mirek, I'd like to see a photo of that!

Please see the TC caps/resistors on Pots. UGLY job much nicer with Fender TC (2 caps and 1 resistor).
All that aside, it does work well. (A couple dabs of "neutral cure" Silastic to stop components running away  )
Regards
Mirek

[murrayatuptown]

Thanks for posting that.

I have been buying small signal and some 7C5 Loctal tubes & have a 40's Zenith floor radio with the chassis containing a 7 Loctal tubes and PP 6V6 outputs. I don't need 7C5's for this, but plan to gut the radio parts & reconfigure the preamp. I have some Loctal pentodes I want to try as triodes. 14" field coil speaker.

I discovered Chinese loctal sockets are a disturbingly different animal so I've gotten several US-made ones which DO cost more.

[tubeswell]

Late to party, but you might find values in this James TS give a flatter EQ response with T and B pots at mid-rotation - with pronounced hump with both pots cut and pronounced scoop with both pots dimed. Tried and tested (acknowledging that it all depends on the output impedance etc of the V1a stage)

[ALBATROS1234]

I have to go back and read through the progress of your build but to comment on the 7C5, I got a couple hundred NOS and used but good Loktals most of which I use on radio repairs, but I do have a handful or two of 7C5 and 7F7 NOS. These are said to be equivalent to 6V6's and 6SL7's but they seem to have a different tone. For instance, I made some 6V6 to 7C5 adapters using the bottom pin base of a Octal tube wired to a Locktal socket using a 1" EMT Coupling as the metal sleeve in which to mount them in fits perfectly. I also made a few 6SL7/6SN7 to 7F7/7N7 adapters. In all cases they sound noticeably crisper with more pronounced highs and upper mids and less noticeable lows. Not sure why this would be because to my knowledge most if not all Loktals were made by Sylvania so you would think this would be the guts of a Sylvania 6V6 in a glass envelope with a different type of base but, putting the same era Sylvania 6V6's and/or RCA's (which have slightly different flavors but are basically a similar sounding tube) then 7C5's with adapters in a PP 6V6 amp I found them to be not the same sounding tube at all. Not bad just different. Just saying you may need to tweak coupling cap values etc to make the circuit sound the same as an original 6V6 circuit as the 7C5's have this really crisp thing going on, not ice-pick but noticably different. The 7F7's are closer to the 6SL7's and tbh I almost like the 7F7's a little better(at least the few I have tried). Just thought I would detail my findings for those interested.

[dwinstonwood]

hello tubeswell and ALBATROS1234,
I never built the 7C5 PP amp. The project kept morphing and I ended up building this project. Of the eight tube guitar amps I've build since I started this hobby in 2020, this one is by far the best sounding of them all. It uses all NOS Octals.