Recommended 15" Speaker

[Haloskater24]

Well Wally the whole idea was to End up with a 5G14 Showman so I don’t want it to sound like 5F8a rather but just take some elements from it to make the 5G14 a little closer to Tweeds as the 5G amps were. So this is really a “High Powered” 5G13 Vibrasonic but i was just seeing what I could borrow from the 5F8a.

 

[Wally]

That 5G13 is nothing like a tweed amp as far as the preamp is concerned. The phase inverter and output of the big tweeds...as I noted....was a departure for Leo in his quest for ‘bigger, bolder and cleaner’. Start comparing the schematics of the 5F8A, the 5G13, the big 6G amps, and the BF amps and you will see what I am talking. about. I am trying to simplify your thought process for this build. You are wanting something that Fender never built....a 5 tube preamp with harmonic vibrato with a 4 x 6L6 output section. Just build the 5G13 with 4 6L6s.
if you want to have some kind of ‘throwback’ to the 5F8A with that preamp in front of it, then you will need to work with the values of the component in the phase inverter and output section. There is not that much difference, though.....with the NFB having the most effect, I would think.

 

[hotraman]

I've used two 15" speakers for my pedal steel and electrics. 1. 15" Sica Neo speaker ( Jensen) from Italy. 4 ohm.
2. Big Ben 15" British Voiced. 8 ohm.
Sounds better and responds tighter when used with my Katana head V1.

 

[Haloskater24]

@Wally So basically the pre amp is what gives the amp it’s character ? Could you mix and match a different tone stack with a different pre amp or are they one in the same ?

 

[Ringo]

I had a Celestion G15V-100 Fullback 15" 100W 8 ohm Guitar Speaker a while back and it was to me a GREAT sounding speaker clean and with gain.

 

[JRapp]

I had a Celestion G15V-100 Fullback 15" 100W 8 ohm Guitar Speaker a while back and it was to me a GREAT sounding speaker clean and with gain.

I have wondered about that speaker since I had good luck with the 70s G15-80---a very balanced speaker that worked great in my tweed Pros. Decent clarity and high end in the G15V?

 

[Wally]

@Wally So basically the pre amp is what gives the amp it’s character ? Could you mix and match a different tone stack with a different pre amp or are they one in the same ?

Haloskater, compare the schematics of the 5F8A and the 5G13. There are great differences in how those two preamps are built, and yes the preamp is a big part of Determining what an amp does. The outputs are much more similar. You are going off into amp design. I am not an amp designer, but I am going to think that one would want and need to know what the goal was in order to put together a circuit that would do that.
What amp have you played or heard that attracts you? If you want the harmonic trem, then I would strongly suggest that you use one of Leo’s circuits and stay true to it as much as possible until you get it working. Then, perhaps you could shape certain aspects to your liking. Less or more midrange? Less or more negative feedback?? The number of power tubes is not a major deal....if you want that 80-100 watts of power for some reason, then make sure the power tranny can handle the tubes’ demands and build with an OT that does what you want there. If you want a big 5E3, then build a 5E5A. Imho, the 5E3 circuit is alone in the tweed era from 1955 through 1960. If you want a 5F6A thing, then build that or a 5F8A. The 5E5A,5F4 and 5E7 amps are a subgroup of their own in that era of tweeds. the Champ/Princeton are a Subgroup, and the Tremolux and Vibrolux are a subgroup. The 6G era has maybe three subgroups of guitar amps....those with harmonic trem and complex tone controls are in one group, those with bias vary trem and two knob tones stacks, and the Deluxe and Princeton with bias vary and single tone controls. The BF era of guitar amps saw one basic preamp with a difference in the type of trem...bias vary versus opto-isolator.
What do you like to hear and play??? That is the question I have to ask and answer when I want another amp.

 

[Haloskater24]

Haloskater, compare the schematics of the 5F8A and the 5G13. There are great differences in how those two preamps are built, and yes the preamp is a big part of Determining what an amp does. The outputs are much more similar. You are going off into amp design. I am not an amp designer, but I am going to think that one would want and need to know what the goal was in order to put together a circuit that would do that.
What amp have you played or heard that attracts you? If you want the harmonic trem, then I would strongly suggest that you use one of Leo’s circuits and stay true to it as much as possible until you get it working. Then, perhaps you could shape certain aspects to your liking. Less or more midrange? Less or more negative feedback?? The number of power tubes is not a major deal....if you want that 80-100 watts of power for some reason, then make sure the power tranny can handle the tubes’ demands and build with an OT that does what you want there. If you want a big 5E3, then build a 5E5A. Imho, the 5E3 circuit is alone in the tweed era from 1955 through 1960. If you want a 5F6A thing, then build that or a 5F8A. The 5E5A,5F4 and 5E7 amps are a subgroup of their own in that era of tweeds. the Champ/Princeton are a Subgroup, and the Tremolux and Vibrolux are a subgroup. The 6G era has maybe three subgroups of guitar amps....those with harmonic trem and complex tone controls are in one group, those with bias vary trem and two knob tones stacks, and the Deluxe and Princeton with bias vary and single tone controls. The BF era of guitar amps saw one basic preamp with a difference in the type of trem...bias vary versus opto-isolator.
What do you like to hear and play??? That is the question I have to ask and answer when I want another amp.

The Amp that I’ve heard and loved the sound of was the 5F8A BUT I also love Curtis Mayfield’s sound on his early Impressions records (1963-1965) During those recordings he used a 5G/6G amp that was very thick/midrangey with Harmonic Tremolo. I’ll show you 4 examples of of the sound I’m going for. 5F8:

5G/6G:
I like the big soft top yet sturdy bottom end of the sound Curtis is getting, I like that it is not scooped at all.Those examples of curtis Sound is what I want but I want something that could do that but still have the roar of the 5F8a.From what I’ve heard the Blond Showman 6G14/6G14A doesn’t really breakup at all unless maybe way up the dial.These examples are best I can give.Oh and harmonic tremolo is a MUST.

 

[Wally]

okay, I have a final suggestion. It covers all of your bases, but you will need to build it on the 6 x 12aA-7 harmonic trem circuit. There is a triode left idle in that scheme, so this is doable....if you can put the design together to work properly. Build a 6G14 with the Vib channel as stock. Build the Normal channel as a 5F8A preamp utilizing that idle triode for the cathode follower that the 5F8A preamp needs. Have an adjustable NFB loop. Have a switchable midrange resistor in the preamps to eliminate scoop. One key to these 6G amps is that tapped treble pot. My 1963 Pro prototype has those treble pots...only BF amp I have ever seen with them in the circuit. It does sound different from any other Bf/SF Fender guitar amp I have heard.
does that scratch your itch??? A true dead ringer for something you ain’t never seen before! It would be an ambitious second build, and I am not the one to help with anything except initial design suggestions. It will also be more amp than anyone except a big stage gigging pro would need. Building it on the basic 6G7A Design would calm things down a tiny bit.

 

[avspecialist]

It looks like this thread went from recommending a 15 inch speaker to a new hybrid design. Wally has some good recommendations. I would tend to think of you wanted a 15 inch speaker for that era sound it probably would be a Jensen, I’m not sure of which model. Other than that, I would use either a JBL grey frame D130F or what I have a D140F, which to me sounds a little less bright. Also I do like the Weber California speaker, but it needs a lot of hours to loosen up. When they are new they are very stiff and bright and limited in low end response.

 

[Wally]

It looks like this thread went from recommending a 15 inch speaker to a new hybrid design. Wally has some good recommendations. I would tend to think of you wanted a 15 inch speaker for that era sound it probably would be a Jensen, I’m not sure of which model. Other than that, I would use either a JBL grey frame D130F or what I have a D140F, which to me sounds a little less bright. Also I do like the Weber California speaker, but it needs a lot of hours to loosen up. When they are new they are very stiff and bright and limited in low end response.

yes, wondering about speakers before settling on an amp design is definitely putting the horse before the cart imho. Of course, a knowledgeable tube amp designer could start with a speaker and design the circuit toward the particulars of that speaker, I suppose. That would not be my plan of attack, though.
I like the Weber Cali, but not with a metal dust cover....just as I don’t like any metal dust cover in a guitar amp. Metal dust covers were invented in the late 1940s by Altec as a way to achieve some added high end in high fidelity musical reproduction and P.A. systemS....that were not being driven into distortion. I have yet to meet a guitar amp in proper condition that needed additional high end, and metal dust covers yield very harsh high freq distortion characteristics.

 

[avspecialist]

Hi Wally, I agree with what you are saying. My cali’s have the paper dust cover. I went that root, because the JBL K120’s I have in my 68 Bandmaster cabinet. It has that little top end tiz that when I home playing is annoying to me. It is not as noticeable in a live situation. Also, it may be why I like the JBL D140F in my “Tone Ring” cabinet. That speaker doesn’t seem to have that tizzyness. I definitely do not like metal domes in Home Stereo systems.

 

[P Thought]

@Wally, I wish you'd write a book. I'd like to read it.

 

[Wally]

@Wally, I wish you'd write a book. I'd like to read it.

I appreciate that, P Thought, but you have to believe that there are quite a number of books written by people who have much greater understanding of these things than do I. Whatever I know is the result of reading such books and of observation what comes my way.

 

[Ringo]

I have wondered about that speaker since I had good luck with the 70s G15-80---a very balanced speaker that worked great in my tweed Pros. Decent clarity and high end in the G15V?

I had one in a 1960 Fender Vibrasonic, it sounded great!

 

[JRapp]

Ringo---I had two and they are both blown now. I have the frames and been looking for a recone one of these days. A great 15" speaker.

 

[Haloskater24]

okay, I have a final suggestion. It covers all of your bases, but you will need to build it on the 6 x 12aA-7 harmonic trem circuit. There is a triode left idle in that scheme, so this is doable....if you can put the design together to work properly. Build a 6G14 with the Vib channel as stock. Build the Normal channel as a 5F8A preamp utilizing that idle triode for the cathode follower that the 5F8A preamp needs. Have an adjustable NFB loop. Have a switchable midrange resistor in the preamps to eliminate scoop. One key to these 6G amps is that tapped treble pot. My 1963 Pro prototype has those treble pots...only BF amp I have ever seen with them in the circuit. It does sound different from any other Bf/SF Fender guitar amp I have heard.
does that scratch your itch??? A true dead ringer for something you ain’t never seen before! It would be an ambitious second build, and I am not the one to help with anything except initial design suggestions. It will also be more amp than anyone except a big stage gigging pro would need. Building it on the basic 6G7A Design would calm things down a tiny bit.

Haha This is perfectly put Wally, this sounds like the most realistic option. I dont mind the power of 80 watts, ill find somewhere to crank it whether it be the woods, park or an empty parking garageAs for speakers i see those celestions have been brought up a lot, gotta check those out. Anyone have experience with Altecs?

 

[Wally]

Speakers.....IF you are shooting for the sound you hear that Curtis Mayfield got, you might consider some ‘American’ sounding speakers since that is surely what he was playing through. It seems very difficult to get some 8nfo on his amplification choice. I find no mention of it. I am going to have to try out his tuning, though....open F#....low to high F#,A#,C#,F#, A#,F#.

 

[avspecialist]

I have an Altec 15 it says on the box I got it in, that it is a 421-8H series 2, presently it’s in a cabinet with about 24 screws on the back and possibly later on I’ll opener up th take a picture of the back. Does the model number I’m posting look correct. Any way I have tried it in the test cabinet I made and so far it only sounds Ok. I like the JBL D140F better so far.

 

[schmee]

I had a Celestion G15V-100 Fullback 15" 100W 8 ohm Guitar Speaker a while back and it was to me a GREAT sounding speaker clean and with gain.

I should have an amp arriving this week with one of those, I'll be interested to see how it sounds as I've not tried those before.