Fromel mods good or bad?

KokoTele

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A thread on a facebook group has made me curious... I've read over and over about how the Fromel mods are desirable in the Hot Rod series of amps. In this discussion about how they've improved an amp, someone chimed in and said "Most pro techs know to stay away from Fromel."

Is there something inherently bad about their mods and kits? I glanced at the Fromel page and everything seems reasonable, and a tiny bit of googling hasn't turned up anything that would make me think there's something wrong with it.
 

RWB

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I installed a Fromel upgrade kit into my 1998 Blues Jr last year and I'm happy with the results. It included some reliability items (power supply caps, cooler output tube bias, Switchcraft input jack) as well as tonestack and reverb circuit mods. I've used it recently at rehearsals and it sounds great. But what do I know since I'm not a pro tech.
 

Andy B

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Out of curiosity I installed Fromel’s Global Master Volume kit on a buddy’s Hot Rod Deville. I was pleasantly surprised how well it worked. His Blues Jr kit is very reminiscent of the Bill M mods I had done for customer’s in years past. Not familiar with the other kits.
 

Lowerleftcoast

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Is there something inherently bad about their mods and kits?
Disclaimer... I have not seen the particulars of the several Fromel mod kits. Going from memory, the Blues Jr kit is much like the BillM mods.

From what I have read on the Fromel site some of the changes are an upgrade in the quality of the part(s). Nothing wrong with that. These amplifiers were built at a price point and some parts were likely chosen due to cost restraints.

Most mods are designed to change the character of an amp. One could argue the original design was chosen for a reason and it performs as designed. Why change it? I have heard from several tech's who agree with this argument.

I can understand wanting to Mod an amp so... why not? The biggest concern I have is, many mods are designed to provide more bass. Bass takes power. The Blues Jr and Pro Jr are equipped with, what some would argue, under-powered transformers. Trying to eek more bass from these amps taxes an already taxed PT. Speaking from a tech's point of view, this is not a good idea. The mods I am aware of, (remember... I am not sure about the Fromel mods), do not consider the limitations of the original design.

(After awhile, the BillM Blues Jr (more bass) mods have morphed into changing the PT, OT, and the speaker. The three most expensive bits in an amplifier. It starts to make financial sense to just start with a different amplifier rather that mod the BJ into something else.;))
 

KokoTele

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To avoid further speculation, here's the info from Fromel's site. Some of the components are swapped for higher quality, some for different values. Jumpers are added in a few places, and instructions are given on how to improve the lead dress.

The text is a bit rambly:

Hot_Rod_Deluxe_Supreme_Kit.png


Tone Stack - Get rid of that farty bottom, honky mids, and lack of clarity. High Quality WIMA Box Caps with corrected values for the Bass and Mid Cap and corrected value for the slope resistor. What about the Treble cap? replace the cheap ceramic cap with a high quality Silver Mica cap. The result is an amp that sounds huge and warm with nice top end sparkle, not dark and buried in the mix.

Twin Mod - Fix the mids on the amp and get rid of that flabby bottom. This mod enables you to take all the mids out of the tone allowing more flexibility and versatility. This is accomplished with just a short jumper wire but the result is far better control of your tone.

Brightness - Like to play at low volumes but find the amp too dark? The brightness mod adds sparkle to your tone at low volumes. As you turn your amp up the brightness mod loses its effect so the amp never sounds brittle at high volumes.

Power Stiffening - Doubles the capacitance in the first filter stage, this reduces hum and increases reserve power for solid bass and better transience for incisive picking, This mod gives the amp the extra torque it needs to push through strong when you are playing hard. This also takes some stress off the output transformer increasing its life span.

Lead Master Volume - Ever wonder why this amp gets extremely loud after you turn it up past 2. Fender uses a linear taper pot for the Master Volume when it should be an audio taper. This mod gives you usable control of the drive channel so you can get good tone without playing at stadium volume.

Power Resistors- Many problems with the Hot Rod Deluxe, especially the older ones are from the power resistors that control switching. Two new power resistors installed properly will avoid many problems down the road.

Plate Load Resistors - Replace all the plate load resistors with 1% 1/2 Metal Film resistors. This amp can develop a loud crackle/static that is caused by the plate load resistors. This mod fixes or prevents this problem and also upgrades the resistors for reliability and reduced hiss.

Reverb Mod - Why does the reverb in this amp become a complete wash after turning it up past 3 especially at low volumes? This mod makes the reverb more controllable, fuller, and more natural. This is an easy mod that is nothing more than clipping one wire but the result is amazing.

Global Master Volume Mod - Now included in both the Complete and Supreme mod kits is our Global Master Volume Mod. This mod allows the master volume to work on both the clean channel and the drive channel. You can now dial in your tone on the clean channel and dial down the master volume for more versatility at home, in the studio or on stage.

Switchcraft Input Jack - Your input jacks are soldered directly to the circuit board, apply some tension when the amp is plugged in and you could cause major damage to the circuit board in the amp. This mod gets rid of the wimpy plastic input jacks and replaces them with high quality metal switchcraft jacks that are panel mounted and NOT directly soldered to the circuit board. Included is a shoulder washer and isolation washer so the input jacks do not ground directly to the chassis and prevents ground loops. The jacks come with high quality, Teflon Coated, Silver Plated Solid Copper Core wire. The solder I use is Silver bearing. This is the same quality you will find in high end boutique amplifiers costing thousands of dollars. Newer Hot Rod Deluxe amps have a better quality Neutrik input jack which are better than the older amps but they are still attached directly to the PCB.

Proper Lead Dress - Take a look inside a boutique tube amp and you will see all the wires carefully twisted and placed for greatest reduction in oscillation and noise. The Hot Rod Deluxe has all the internal wires zip tied together. I give clear instructions on dressing the leads inside the amp for optimal performance, this results in lower noise and less chance for oscillation.

The Recap Kit includes

Replacements for all of the power filter and cathode bypass caps with high quality F&T and Nichicon caps. Older Hot Rods that are made in the USA are all getting due to have their filter caps replaced and many of the current Hot Rods made in Mexico are known to have leaky filter caps. The recap kit rectifies these issues.
 

Lowerleftcoast

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Fromel Hot Rod Deluxe kit. $99.95

Quick search at Tube Depot and Mouser...
FT 100uF 450v $8.95
FT 22uF 500v $3.95 x 3
Silver Mica 100pF $0.30 x 2
Silver Mica 250pF $0.50
Wima box cap .1uF $0.96
Wima box cap .022uF $0.47
Wima box cap .015uF $0.55
Sprague 25uF 25v $1.67 x 3
Nichicon 1uF 100V $2.13
1/2 W MF resistors $0.15 x 8
5W 470R resistors $0.45 x 2
Jack $2.25 x 2
Pot $3.95

Total $41.57
This doesn't include the bits of wire, instructions, or shipping.

The cost of the kit may be a reason for a tech to advise against buying the kit. A tech should know how to do all of the work without instruction.
 
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Jon Snell

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Fromel HRD kit. $99.95

Quick search at Tube Depot and Mouser...
FT 100uF 450v $8.95
FT 22uF 500v $3.95 x 3
Silver Mica 100pF $0.30 x 2
Silver Mica 250pF $0.50
Wima box cap .1uF $0.96
Wima box cap .022uF $0.47
Wima box cap .015uF $0.55
Sprague 25uF 25v $1.67 x 3
Nichicon 1uF 100V $2.13
1/2 W MF resistors $0.15 x 8
5W 470R resistors $0.45 x 2
Jack $2.25 x 2
Pot $3.95

Total $41.57
This doesn't include the bits of wire, instructions, or shipping.

The cost of the kit may be a reason for a tech to advise against buying the kit. A tech should know how to do all of the work without instruction.

The 470R resistors are only to discharge the capacitors before starting so not needed in a kit for a person who knows. The Fromel mod kit is an excellent starting point.
The improvement to the sound this little amplifier can produce makes the kits worth fitting. In my view.
The tone band is more effective and the bias gives long life. I use slightly different values in my calculations and my clients say the tone their amp now produces gives more control and a wider spectrum. I charge £75 ($93.25) including fitting and testing for the Blues Junior.
Don't forget, if in the UK, to set the mains input tapping to 240volts, don't leave it at 230volts!
 

KokoTele

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Fromel Hot Rod Deluxe kit. $99.95
Total $41.57
This doesn't include the bits of wire, instructions, or shipping.

The cost of the kit may be a reason for a tech to advise against buying the kit. A tech should know how to do all of the work without instruction.

Fromel's intellectual property (and labor for sourcing and packaging all the components) has value. Is it $50 worth of value? Maybe. The market mostly says yes. Honestly, my time is in short supply and $50 seems like a bargain if it saves me that much time.

Still, that doesn't seem like a reason why the mods should be avoided. Seems like this comment was from a punter that needs to hear his own voice.
 

ukepicker

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Still, that doesn't seem like a reason why the mods should be avoided. Seems like this comment was from a punter that needs to hear his own voice.

I didn't take it that way. I think @Lowerleftcoast was just saying that qualified tech might balk at the price of the kit, based on the individual price of the parts. A pro tech doesn't need the instruction, but I sure do.

Sounds like @Jon Snell does a similar mod for less than $100.

I'm not a skilled amp tech and I have no idea where to even find one in my area. But I can follow instructions. $50 for someone to source and assemble the kit AND give me detailed instructions on how to do the job seems like a reasonable price to me.

I've been looking at these kits for some time now (for my Deville, and previously for a blues jr.).
 




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