Frankenstein Vintage Hi-Fi into 5E3 build...IT LIVES!

[bastardbus]

Hi guys, new to this site.

I am interested in building a Fender 5E3 circuit amp from scratch. I have been into vintage Hi-Fi Audio equipment the past couple years. Rebuilding, and refurbishing amps, tuners and TTs. Anyhow, I have quite an abundance of `50s era audio parts and being a Guitar player the past 25 years I thought it would be a great idea to build up a 5E3 from parts I have. I have a pretty good idea of what I am going to use for cabinet, speaker and components but I wanted to double check on certain things like the PT and OT.

First the Power Transformer. I have a nice one from an RCA 610V console with amp chassis RC 610C. The chassis consists of the tuner and amp as one. The PT powers the following tubes 6BE6, 6BE6, 6BA6,6AU6, 6AL5,6SQ7,6SQ7,6K6GT,5Y3GT. Each of the 6V tubes has a .3A draw and the 5Y3 is 2AMP. The 5E3 runs 5Y3,6V6,6V6,12AU7,12AX7 from my specs that the 6V6s draw .3A each and 12Vs in parallel draw 6V @ .6A each and 2A for the 5Y3 rectifier. Thus the original RCA amp has just a .6A more draw then the 5E3. So I am assuming this RCA's PT should be just perfect for a 5E3 build. If I am incorrect about something and this PT would not work for some reason, please let me know I am here to learn.

Thanks!
T

[d95err]

The PT seems OK (provided the voltage is at a reasonable level). The first tube in the 5e3 should be a 12AY7, not 12AU7 though.

Or you could build the amp with those octal tubes. Earlier Deluxes (5a3, 5b3, 5c3) had octal preamp tubes and from what I've heard, they sound great in a 5e3 circuit as well.

[bastardbus]

I have not seen the voltage out on the 5E3. I thought it would be similar. Most Hi-Fi stuff is 290-310 out. Now that you mention it I looked through some 5E3 schematics but only one had a voltage of 375. Is that correct? That sounds like it might be an issue. I don't have the exact voltage for this RCA PT yet I need to hook it up and check it but I bet it is around 300 which sounds like it will be too low for this amp.

[Firestorm]

6V6GTs draw 450mA; 12A*7s with parallel heaters draw 300mA, so you have plenty of heater current. According to the Riders schematic for the model, B+ will be 315V, so probably a bit low by Fender standards, but perfectly workable albeit at slightly lower output. You could "cheat" and rectify with solid-state diodes for higher B+; you probably wouldn't miss the sag, since the cathode bias will sag too. 6K6s draw a little less HT current than 6V6s, but with the smaller tube count, you should be fine.

[bastardbus]

6V6GTs draw 450mA; 12A*7s with parallel heaters draw 300mA, so you have plenty of heater current. According to the Riders schematic for the model, B+ will be 315V, so probably a bit low by Fender standards, but perfectly workable albeit at slightly lower output. You could "cheat" and rectify with solid-state diodes for higher B+; you probably wouldn't miss the sag, since the cathode bias will sag too. 6K6s draw a little less HT current than 6V6s, but with the smaller tube count, you should be fine.

I am going to do a test of this transformer tonight to find out the voltages of all the windings. http://www.radioremembered.org/xfmr.htm From the specs on parts list info for PTs in other very similar Hi-Fi amps I am sure the available B+ from this PT should be more then enough to handle the higher plate-grid voltages.

[David Root]

Now that that is settled, the key question is do you have a vintage output transformer that will work? That will make a huge difference in tone.

[bastardbus]

I tested the PT tonight and she seems great. At 120VAC I have 730VAC, 7VAC and 5.9VAC on all the windings. It also has a center tap with 362VAC. From what the original tube set up was this should be perfect for a 5E3 circuit.

Now that that is settled, the key question is do you have a vintage output transformer that will work? That will make a huge difference in tone.

I have the OT from this Hi-Fi unit as well as several others that should work, Like the PT I need to check into which OT will be best for the 5E3.

I did a crude mock up tonight to see if the chassis and speaker cabinet would work out before I put any work into building the amp. I did have one concern tonight when I installed the hi-fi chassis into the cabinet. The tubes are fairly close to the speaker magnet. Not close enough to touch but probably close to the magnetic field of the speaker. Would this affect the tubes operation? This is something I never have had to look into but since this is a custom build of sorts I should address these questions. Here is a couple pics of the cabinet with speaker and chassis installed. I have a few options to move the tubes around, anyone see any issues with the tubes location to the speaker magnet?

[IMG:640:480]http://i160.photobucket.com/albums/t167 ... a010-1.jpg[/img]
[IMG:640:480]http://i160.photobucket.com/albums/t167 ... a009-1.jpg[/img]
[IMG:640:480]http://i160.photobucket.com/albums/t167 ... a012-1.jpg[/img]
[IMG:640:480]http://i160.photobucket.com/albums/t167 ... rca014.jpg[/img]
[IMG:640:480]http://i160.photobucket.com/albums/t167 ... rca015.jpg[/img]
[IMG:640:480]http://i160.photobucket.com/albums/t167 ... rca016.jpg[/img]

[d95err]

The look of that amp will be awsome!

I wouldn't worry about the distance between the tubes and the speaker. It looks fairly normal for a combo amp.

[Cliff Schecht]

Do you know anything about that speaker? I have one that looks very similar and sounded great until I blew it.

[bastardbus]

Do you know anything about that speaker? I have one that looks very similar and sounded great until I blew it.

Nothing, I bought it at an antique store in a wall theater style wall mounted cabinet for $8. I checked the manufactures code on the rim and I could not find a match for who built it. I recall the code is 122. I hooked this speaker up to my little `54 Valco Oahu amp and it sounded absolutely wonderful. I installed it in this Ampro cabinet as it was a better cabinet for this project. The Ampro had a Jensen that was liberated by the previous owner. He sold me the cabinet alone for $5. I thought it would be a great basis for this project. The amp chassis was a garbage pick and I have so many tubes those are basically free as well. I am trying to do this entire amp from as much free stuff and parted out items I have on hand, a Frankenstein of sorts.

[Firestorm]

I'll bet the EIA code is the "145" stamped on the magnet cover, in which case it would be made by "Cinaudagraph." Sounds logical based on what it came out of.

I don't think you'll be able to use the original OT. The 610V schematic shows a 2-ohm speaker and since 6K6s were typically run with 12K plate-to-plate, so that would put the OT on a different planet.

First step is to check the speaker's impedance and work from there. You said you had other OTs available; if you have access to a signal generator, you can work out their turns ratios. Power handiling you'll have to guess at by size and weight.

[bastardbus]

I'll bet the EIA code is the "145" stamped on the magnet cover, in which case it would be made by "Cinaudagraph." Sounds logical based on what it came out of.

I don't think you'll be able to use the original OT. The 610V schematic shows a 2-ohm speaker and since 6K6s were typically run with 12K plate-to-plate, so that would put the OT on a different planet.

First step is to check the speaker's impedance and work from there. You said you had other OTs available; if you have access to a signal generator, you can work out their turns ratios. Power handling you'll have to guess at by size and weight.

Great tip! I really appreciate the helpful info.

I have some other OTs that are from hi-fi amps near identical in tube outlay to the 5E3, they are dual 6V6s in push pull that run single or dual alnico 4ohm 12 inch speakers. This speaker pictured I measured in at 6.5ohm which is close to the original 5E3 design. I do have some additional `55-`58 era RCA 12 inch speakers from Hi-Fis as well at 4 Ohm each. I have HEARD hi-fi speakers are not a good use on guitar amps but was not sure if that was JUST present day speakers or included `50s era speakers as well.

A signal generator and oscilloscope are the next buy on my list. I need to educate myself on what to look for when buying one is there someplace or someone out there that can school me on what to look for when buying one? I guess that is for another thread?

This amp is a learning process for me, it is a good way to learn what goes with what, what to do and not to do and how to determine what correct parts go with a circuit design and why. My next thing I need to know is the correct layout for this amp. I know the PT and OT should be perpendicular to each other because of magnetic fields and noise. Is there any tips on proper tube placement? My concern was the speaker magnet as well being within inches of certain tubes. Any tips is greatly appreciated, I am looking for AMP building 101 if necessary.

T

[bastardbus]

Ok guys I have an OT here on hand that was on a P-P 6v6 amp, it looks to be an early replacement OT. Here is the info on the tag on the top.

Merit A-2904
Primary 4000-14000ohm
Secondary .17-32ohm

Ok here is a nice bit of info I found on the net that shows all the values at the different taps. Would this be a good candidate for using on this amp?

[bastardbus]

I wanted to thank folks on this forum for help with this build. She LIVES! Here is the story on this build I typed up for the Vintage Radio Forums I hang out on.

A little over a year ago I was just getting into this old phono-hi-fi hobby. I had friends, scrapers, old car guys bringing me any old radio-phono they found for free and just dump it on my back porch. One of them was a big ole' turd of a`47 RCA 610V2 console. This thing led a rough life. The veneer was falling off the cabinet, the speaker gone, and it had odd pieces of baby furniture nailed to it (???) and needless to say it was no where near working. I tried to pass off the parts to folks on here for free but no one wanted the old girl.
[img:500:364]http://www.radiomuseum.org/images/radio ... 936270.jpg[/img]

She had been sitting here long enough and since no one wanted this old beast I thought I should build something out of the amp-tuner chassis. I decided on a clone of Fender 5E3 Tweed Deluxe `55-`60 Guitar amp. This being my first guitar amp build, I decided to do this as cheaply as possible using nothing but freebies, garbage picked items and spare vintage hi-fi parts which I thought would lend to the tone, be fun and at least cheap if it did not turn out well LOL

The amp chassis and transformers are from the 610V2 console. The cabinet is a `40s Ampro Movie Theater external speaker cabinet I picked up for $5 (less the original Jensen speaker) at the Toledo Hamfest. The speaker I wound up using is a '69 Jensen C12R scavenged for free from an old solid state organ left on the curb at the Montessori school in Ann Arbor Michigan, found after a fancy dinner we had attended. (Picture me in a suit and tie, screwdrivers in hand, kneeling in dirt working feverishly on this HUGE old turd of an organ as cars from the dinner I was just at drive by and occupants stare...LOL) Can you believe my wife puts up with me? God bless her! The tubes were all vintage freebies from parted out radios, record players and hi-fis with the exception of the 12AY7 which cost me $10 off eBay...grrrrr! Other then that tube and hand full of new caps, resistors, pots and jacks I only have about $30 into this beast. I was pretty proud of that since the hand wired Fender Custom Shop 5E3 lists at $2699 new!

Here is the 610V2 amp-tuner chassis all stripped down to bare bones ready to be built up.
[img:640:480]http://i160.photobucket.com/albums/t167 ... rca016.jpg[/img]


This is Fender's 5E3 circuit and the amp all built up.
The RCA 610V2's PT and OT where just the right specs for the 5E3.
[img:480:640]http://i160.photobucket.com/albums/t167 ... /f_5e3.gif[/img]
[img:640:480]http://i160.photobucket.com/albums/t167 ... rca052.jpg[/img]
[img768]http://i160.photobucket.com/albums/t167 ... rca055.jpg[/img]


Here the vintage Ampro Movie Theater speaker enclosure I used for the cabinet. These pics are just the amp mock-up to make sure it works before finally assembly but that cabinet worked wonderfully.
[img:640:480]http://i160.photobucket.com/albums/t167 ... rca001.jpg[/img]
[img:640:480]http://i160.photobucket.com/albums/t167 ... rca002.jpg[/img]
[img:640:480]http://i160.photobucket.com/albums/t167 ... rca050.jpg[/img]
[img:640:480]http://i160.photobucket.com/albums/t167 ... rca053.jpg[/img]

Of course you have to hear how she sounds. I put a video up on YouTube of how the amp sounds with my wonderful Custom Shop Telecaster straight into her. Here is the link, make sure and turn it up a bit to hear the wonderful vintage tone of this amp!
http://www.youtube.com/watch?v=vsJoXdHNC3Y

[C Moore]

I am looking at the dates of your posts......
How fast did you build this.?
That amp is AWESOME looking. Sounds great with your Tele. I am sure it sounds even better/warmer in person.
Well Done......!