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Post subject: Planning stage of building an 5F2A Princeton
Posted: Mon Sep 14, 2015 9:54 pm
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I've been looking for a while and finally decided to put my plan together for a home brew 5F2A chassis and have maybe 3 or 4 questions for the group.

Have been looking at a Hoffman kit but I want to get the right parts "right" by picking certain innards so I have a clone with respectable tone. I don't want a clone just to say I have a Princeton clone - if that makes any sense.

http://hoffmanamps.com/MyStore/perlshop.cgi?ACTION=enter&thispage=Amp_5F2AParts.htm&ORDER_ID=!ORDERID!

There are three items I am currently on the fence about:

1. Transformers: The kit comes with a Mojotone. Good enough or should I look for something else, like MM or Allen? If I have a choice of 4 or 8 ohm impedance would one have a tonal advantage over the other?

2. Caps: It comes with a mix of manufactures such as Nichicon, Xicon, Sprague and something that looks like an F&T. I'm thinking Sprague for the filters but would it make a tonal difference if the others are a mixed bag?

3. Speaker: It's not listed as part of the kit, but for bottom end and early break up would a Webber or WGS G10 be a poor choice or should I stick with an 8"?

4. Am I overthinking this or should I just go with the default parts list and let it roll?

What I would like when this is done is to have an amp with as much tone as I can get without embarrassing myself with the neighbors. I can't run my Pro Reverb at its happy place without scaring the kids so I'm thinking a small tube amp might be the ticket. I also enjoy this type of project.

Thanks in advance.


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Tue Sep 15, 2015 1:38 am
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Transformer ; I don't know about Mojotone , never test them .
8 or 4 ohms ?
Why not a multi taps ?
One tap , I'll go to 8 ohms and you can use it with a second 8 ohms speaker if you want ,it take 4 ohms load

I'll put a 10 inches spkr if you can

Do you know how to solder ? Most trouble came from bad solder .

Capacitors ; I won't buy Xicon, Nichicon , I'll use F&T , Sprague


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Tue Sep 15, 2015 2:15 am
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Randy70065 wrote:
I've been looking for a while and finally decided to put my plan together for a home brew 5F2A chassis and have maybe 3 or 4 questions for the group.

Have been looking at a Hoffman kit but I want to get the right parts "right" by picking certain innards so I have a clone with respectable tone. I don't want a clone just to say I have a Princeton clone - if that makes any sense.

http://hoffmanamps.com/MyStore/perlshop.cgi?ACTION=enter&thispage=Amp_5F2AParts.htm&ORDER_ID=!ORDERID!

There are three items I am currently on the fence about:

1. Transformers: The kit comes with a Mojotone. Good enough or should I look for something else, like MM or Allen? If I have a choice of 4 or 8 ohm impedance would one have a tonal advantage over the other?

2. Caps: It comes with a mix of manufactures such as Nichicon, Xicon, Sprague and something that looks like an F&T. I'm thinking Sprague for the filters but would it make a tonal difference if the others are a mixed bag?

3. Speaker: It's not listed as part of the kit, but for bottom end and early break up would a Webber or WGS G10 be a poor choice or should I stick with an 8"?

4. Am I overthinking this or should I just go with the default parts list and let it roll?

What I would like when this is done is to have an amp with as much tone as I can get without embarrassing myself with the neighbors. I can't run my Pro Reverb at its happy place without scaring the kids so I'm thinking a small tube amp might be the ticket. I also enjoy this type of project.

Thanks in advance.


Allen and Heyboer both make excellent iron without the robber-baron prices that MercMag demands. A multi-tap tranny with 4- and 8-ohm windings would provide the flexible you seek.

For tone caps in a vintage build it's hard to beat Jupiter and Zoso for authentic tweed tone. I would stick with F&T electrolytics for all the filter, bypass, and bias-supply duties.

A 10-inch speaker will afford more sonic options and better overall frequency response than an 8-inch driver. Weber's 10A125S with light doping will deliver a real tasty vintage vibe.

I don't believe you're overthinking this project at all -- the time for planning is now, before you start ordering parts which might ultimately go unused.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Tue Sep 15, 2015 2:19 am
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Retroverbial wrote:
Randy70065 wrote:
I've been looking for a while and finally decided to put my plan together for a home brew 5F2A chassis and have maybe 3 or 4 questions for the group.

Have been looking at a Hoffman kit but I want to get the right parts "right" by picking certain innards so I have a clone with respectable tone. I don't want a clone just to say I have a Princeton clone - if that makes any sense.

http://hoffmanamps.com/MyStore/perlshop.cgi?ACTION=enter&thispage=Amp_5F2AParts.htm&ORDER_ID=!ORDERID!

There are three items I am currently on the fence about:

1. Transformers: The kit comes with a Mojotone. Good enough or should I look for something else, like MM or Allen? If I have a choice of 4 or 8 ohm impedance would one have a tonal advantage over the other?

2. Caps: It comes with a mix of manufactures such as Nichicon, Xicon, Sprague and something that looks like an F&T. I'm thinking Sprague for the filters but would it make a tonal difference if the others are a mixed bag?

3. Speaker: It's not listed as part of the kit, but for bottom end and early break up would a Webber or WGS G10 be a poor choice or should I stick with an 8"?

4. Am I overthinking this or should I just go with the default parts list and let it roll?

What I would like when this is done is to have an amp with as much tone as I can get without embarrassing myself with the neighbors. I can't run my Pro Reverb at its happy place without scaring the kids so I'm thinking a small tube amp might be the ticket. I also enjoy this type of project.

Thanks in advance.


Allen and Heyboer both make excellent iron without the robber-baron prices that MercMag demands. A multi-tap tranny with 4- and 8-ohm windings would provide the flexible you seek.

For tone caps in a vintage build it's hard to beat Jupiter and Zoso for authentic tweed tone.
+1 if he want to go to high end parts

I would stick with F&T electrolytics for all the filter, bypass, and bias-supply duties.

A 10-inch speaker will afford more sonic options and better overall frequency response than an 8-inch driver. Weber's 10A125S with light doping will deliver a real tasty vintage vibe.

I don't believe you're overthinking this project at all -- the time for planning is now, before you start ordering parts which might ultimately go unused.

Arjay


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Tue Sep 15, 2015 8:55 am
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Premium components = superior tone + enhanced durability.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Tue Sep 15, 2015 8:59 am
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1. Transformers: The kit comes with a Mojotone. Good enough or should I look for something else, like MM or Allen? If I have a choice of 4 or 8 ohm impedance would one have a tonal advantage over the other?

Standard equivalent Hammond would also work fine.

2. Caps: It comes with a mix of manufactures such as Nichicon, Xicon, Sprague and something that looks like an F&T. I'm thinking Sprague for the filters but would it make a tonal difference if the others are a mixed bag?

I'd also recommend Jupiter Vintage Yellow caps or Zoso for coupling caps. Trying to achieve original Fender tone. I'd use F&T in the PSU and bypass.

3. Speaker: It's not listed as part of the kit, but for bottom end and early break up would a Webber or WGS G10 be a poor choice or should I stick with an 8"?

Maybe, think about making a head unit, not a combo. Then, you can plug the amp into a variety of speaker cabs. If you have your heart set on a cab, I'd try to shoe-horn a 12-inch into the amp. More variety of speakers to choose from & a much better tone, IMHO.

Good luck! The tweed Princeton clone is a noble DIY.


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Tue Sep 15, 2015 9:47 am
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If you want it to actually sound like a Fender, use a Fender brand OT .
Single tap 8 ohm.
You cannot build a multitap transformer without compromising the original design. In order to pack more secondary windings into the same size package, the wire has to be a smaller guage.
Many original Fender OTs have split or paralleled secondary windings to brighten the tone
Aftermarket transformers often have very different characteristics than the originals. Differences in winding the secondaries, wire guage and lamination thickness and permeability make a huge difference in performance


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Tue Sep 15, 2015 10:31 am
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Tim, from what I read about the tweed era single-ended amps, Fender did not request special windings on the power or output trannies. Leo used whatever shelf stock would work on these amps. Prolly why tweed era amps had several manufacturers of iron.

Most Princeton amps of this period, that I've worked on, had Triad PTs. Very good iron. Maybe, kinda hard to find an NOS one. But, the Hammond irons for SE amps are quite good. I've used them as replacements in Champs and Princeton amp. Faithful voltage and tone-wise. And they last.

http://www.hammondmfg.com/pdf/EDB290AX.pdf

Multi-impedance secondary taps:

http://www.hammondmfg.com/pdf/EDB1760C.pdf


Just my 2¢ worth, of 2¢. :D


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Tue Sep 15, 2015 8:35 pm
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Perfect! This is the kind of feedback I was hoping for. BMW hit the nail with the head-only idea. I could use the 2-12's in my Pro and see how or what I like before building another cab.

The Jupiter caps... I can find tons of 600v but none at 630v which is what the kit recommends. They claim to have been tested to 1200, so is it okay to go with those or is the 1200v claim just marketing gibberish?

You guys are great.


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Wed Sep 16, 2015 12:59 am
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Use the 600 volts caps .


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Wed Sep 16, 2015 2:41 am
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stratele52 wrote:
Use the 600 volts caps .


+1

Most of the coupling caps in Fender's original tweed circuits were rated for 400 VDC or less.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Mon Sep 21, 2015 9:05 pm
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Okay. I have a couple more questions before I get my order together.

1. I found another supplier, BootHill Amps that has an F1 kit with all the parts minus the transformers and tubes, or I can have them added but they are Classic Tone. What kind of reputation do the Classic Tone transformers have? I'm perfectly okay staying with Hammond but thought I would ask for opinions on Classic Tone since the S&H would be the same with or without.

2. I'm really after an F2A so does adding a tone pot make it an F2A? I've searched and found many kits that have been slightly modded from the original Fender design in one way or the other, some better and some not so much. I thought a pot and a cap were needed to make an F1 and F2 but I may be wrong. There's a ton of great reading out there on wiring, hum cancellation, tone tweaking using different caps, etc. For a first time amp project the mods I've found can cloud the original intent but I understand most of the references.

3. Okay, 3 questions. What tubes should I shop for: EH, JJ, NOS, Sovtek, something else?

The supplied caps that come with the kit would be swapped with Jupiter, if I can find what I need, or F&T. I've got some Jupiter caps bookmarked but not all of them.

Thanks again.


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Mon Sep 21, 2015 10:24 pm
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1.) Classic Tone are good trannies. Tone-wise, about the same as Hammond. Hammond iron lasts. Haven't seen a Classic Tone in an amp over 15 years old.

2.) Tone pot and tone stacks are a personal issue. Differs from amp-to-amp. IOW, empiric trial-&-error maybe needed after the amp is finished. Some ppl breadboard this part of the amp, to make modification easier. Then, permanently solder in the final components, when desired end-stage is reached.

3.) Go for NOS 5Y3GT rectifier. Plenty of good ones around. US manufacturers mades great black plate (1950- late 60s). GE made a nice slow warm-up mil spec 6087. Excellent rectifier.

http://www.ebay.com/sch/i.html?_odkw=ge ... 7&_sacat=0

http://www.mif.pg.gda.pl/homepages/fran ... 6/6087.pdf

I'd go for an NOS 6V6GT, also. You only need one. Tungsol (USA) black plates are my favorite. Raytheon 6V6GTY (or any US made 6V6GTY) are also excellent. Brown micanol base, gray glass, black plates.

http://www.ebay.com/sch/i.html?_odkw=ge ... Y&_sacat=0

The Gold Lion B759/ECC83 is a nice new 12AX7 type. Clean top ends. Good bass. Scooped mids. For warmer mids... Look for a nice 5751. The JJ 5751 is ok.

4.) Jupiter only makes coupling caps and F&T only electrolytic (main PSU and bypass) --- AFAIK. There are a lot of coupling cap companies. But IME, the Jupiter Yellow Vintage has a tone closest to the original Astron or Blue MOLDED.

Good luck with your project. Keep us posted! :)


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Mon Sep 21, 2015 10:42 pm
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An optimized tube array would be best assembled once you have the amp completed and you're able to conduct some field tests. There are ample supplies of quality NOS 5Y3 rectifier tubes available so that narrows your choices down. As for power tubes, I'd start with something low cost and readily available -- either the re-issue Tung-Sol, the Electro-Harmonix, or the JJ (but not their 6V6S, which sounds too much like a 6L6GC to perform credibly in a tweed Princeton). From there, it's merely a question of tuning the front end to suit your druthers. For early breakup and compression, you might give the Gold Lion ECC83 a try. For something a little cleaner, a 12AY7 might be the ticket. Or split the difference and use an NOS 5751.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Planning stage of building an 5F2A Princeton
Posted: Tue Sep 22, 2015 8:08 am
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"Standard equivalent Hammond would also work fine...."

+1 again for the Hammond transformers.
Had to replace a PT in one of my amps some years back, and the Hammond has been a sturdy, well-functioning, reliable piece of iron that didn't break the bank, and may actually have improved the amp's tone.


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