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Pignose G40V Questions & Observations


Acidhouse

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There was an excellent thread here that was the official Pignose thread.  The last post was in 2012 and since it doesn't show up on a search of the site, I am guessing it is archived.  Figured it would be better to start a new thread.

Around 2009 or so, I found a used G40v on sale at Musicgoround and snapped it up.  It was my first tube amp.  After a few months, I wound up swapping the tubes and speakers out.  I debated doing some of the other suggested mods but never got around to it.  At the time, I figured it was a good starter tube amp until I moved up to something more impressive.  It never happened.  I've been so happy with the G40V that I haven't really found any reason to swap it out.  

Recently, I spotted another G40V locally for $125.00.  After a little bit of a debate about the necessity of owning two G40Vs, I decided to jump on it.  They don't make these anymore and I would be pretty devastated if mine crapped out.  At worst, I would easily be able to flip it.  I picked it up yesterday and brought it home.  From the pics and the obvious original speaker, I assumed it was all stock.  I plugged them in side by side and was surprised that both sounded great and there wasn't a huge amount of difference between the two.  I remember when I modded my original G40V, it was like a brand new amp.  Later, last night, I got curious.  Yes, the original speaker is still installed but all the Chinese tubes have been swapped out for JJ 6l6s and the preamps had been swapped for JJs as well.  I couldn't quite make out exactly which tubes but I am going to take a look again later today.  

I spent this morning swapping both amps out between two different guitars taking turns plugging each guitar into each amp.  Both amps really have a beautiful tones.  It's more obvious that they are voiced differently and depending on which guitar I was using, which one that I liked better.  So now I have two really awesome amps that each bring a something a little different to the table.

 

Observations/Questions

Serial numbers - Old amp has a different sticker with seven digits.  The sticker is metallic. /  New amp has eight digits and is on a white sticker.

Amp fuse - Old amp has a 3 watt fast blow fuse /  New amp has 2 watt fast blow fuse.

The new amp louder than the old amp.  I tried to keep the settings identical to get a good idea of the differences but the old amp needed to get to 10 - 11 o'clock to get the same volume output as the new amp does at 9 o'clock.

Both amps hum like crazy when the Master is turned past noon.

 

Because of the difference in the fuses and the old issues with the failing transformers, I am leaning towards my "old" amp being the newer version of the amp even though the serial only has 7 digits.  

A question I have is should the amp with the 2 watt fuse be swapped out for a fast blow 3 watt?  

 

 

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21 minutes ago, Acidhouse said:

A question I have is should the amp with the 2 watt fuse be swapped out for a fast blow 3 watt?  

 

Does the back of the amp specify the fuse type and rating? If so (and it should...), stick with that!

You can try contacting Pignose - they might have some information on the amps, including any changes that were implemented in their circuits over their production run. 

https://pignoseamps.com/contact/

 

 

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40 minutes ago, Phil O'Keefe said:

PS One thing that can definitely make a difference in the "loudness" of an amplifier is the efficiency of the speaker. If you swapped out the stock speaker, that alone could account for any difference in perceived volume between the two amps.

 

Thanks Phil.  That's good to know.  I will reach out to Pignose but their cs support was pretty bad for these when they were in production.  It would be great to ask Kager but he died about a year ago.

 

Two Piggies.jpg

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The schematic shows the fuse as being a 1.5A fuse which is in series with a 5A fuse on the board.  They also have a thermal breaker on the ground side. 

Who ever designed the circuit was either a paranoid who knew the circuit was risky or knew the components being used couldn't be trusted.  Modifying fuse values can occur when the amps are moved from the drawing board to actual production and they find the low cost components they contracted wind up having quirks and flaws.  In other words, a circuit designed on a computer can be perfect but that doesn't necessarily mean it will actually work well in the real world.  The quality and tolerances of parts has to be part of the formula when designing a circuit and many times budget parts used in the build fail to meet minimum standards.  

My guess is the amp uses either a low grade Power Transformer or low quality power caps or both.  It may not handle AC power fluctuations or the caps cant handle the surges , especially when pushing the amp hard.  They may have increased the fuse because the originals blew prematurely due to higher then expected current draw.  The repercussion of that is a fuse too high wont blow at all and you wind up blowing the transformer coil instead.  

If I were to guess the original fuses were the ones on the schematic.  The 5A on the board is to protect the amp from jackasses who stock a 10 amp fuse in there when the 1.5A keeps blowing.  As for which fuse might be best, Fuses aren't rated in watts, they are rated in amps.  (watts signify power consumed over time, not the amount of current flowing at any given moment) . 

It doesn't seem to matter if the amp has a 2 or 3 amp Slow-Blo fuse.  Both are below the 5A fuse on the board so both should blow before the amp is damaged.  If you didn't know what fuse was being used you could start with the one in the schematic. Its always best to use the lowest value, which is slightly above the maximum current level.  

Its also possible these amps had their actual current levels measured with a multi meter and the best fuse for that particular amp was chosen. 

It can also be a production change.  They may have increased the amperage to prevent the fuse from blowing when the amp is running normally, or they may have lowered it to prevent meltdowns. 

 

My advice, if its working right. Leave it along.  The worst enemy of an amplifier is the end user who tinkers with stuff they have no business messing with.  Even something as simple as a 50 cent fuse gets factored into a design and the reasons for its being changed can be much more complex as I've described here.  You can research it but without actual measurements and knowing the specs on all the parts in the primary and secondary power circuits you're like a blind man with a white cane navigating a china shop.  Best option for not busting something is stay out of the amp like the warning messages on every chassis is labeled.  Let the professionals  who are educated do mods and repairs. 

As far as tone goes, the tubes and speaker will have the biggest impact on the sound so long as thee weren't major changes to the rest of the circuits.  As far as tubes go I'm noyt a huge fan of JJ  12AX7 preamp or 6L6 power tubes.  I tried them in my Fender amp and lost allot of tone range and volume.  They are pretty durable do well if your amp lacks midrange. Theey aren't very good on the top and bottom ends so big plush sounds aren't their specialty. They can used to make an amp break up early of tame an amp that has too much bass and treble, but the overall volume isn't so hot.  My Fender took at least a 3dB cut in volume  compared to the Groove tubes I had been using.  

I tried several other sets of power tubes and nearly all the popular 12AX7 tubes.  The ones that I recommend are the Electro Harmonix Tubes.  They blow the doors off all other budget tubes for clean headroom and brilliant tone.  Low noise and low microphonics too. 

Tube amp tubes loose quality slowly over time and you wont notice how much of that quality is caused by the tubes because it happens so slowly.  I've put new tubes in the Fender before and heard the normal amount of improvement.  Its been 40 years since I had US made RCA tubes in it which were my favorites.  Those EH tubes made me realize there can be a big difference between popular tubes vs ones that really perform well.  There are some other like the Mullard reissues I'd like to try.  Some of the others are priced on the ridiculous level.  There arent any vintage tubes left worth buying.  The supply of those dried up 30 years ago and anything you find will either be counterfeit or used tubes with too many hours on them to be of any good.  Its real easy to  silk screen a new label on ant tube too.  All this talk about vintage tubes being the holy grail for tone is mostly BS. Most of it was driven by unscrupulous electronic techs cashing in on peoples ignorance.  As a tech I cant blame them.  Its can be difficult to impossible to convince some people who believe in all these voodoo electronic myths and they do have the choice of learning by getting burned when they find that medicine the snake oil salesman sells is bunk or they self educate well enough to avoid such scams. 

Anyway,  If you don't know how many hours the tunes have, I'd put new ones in there. Power supply failure due to tube failure is the most logical reason they'd put 2 fuses and a thermal breaker in the AC circuit.  Its like a car, keep fresh oil in it and you're less likely to have major engine problems.  Beyond that a you can often improve the tone and loudness of an amp by getting a better speaker.  You'd first need to know the specs of that stock speaker which can be difficult, especially when the manufacturer has the speakers made by someone else and branded with their name.  On average, most stock speakers typically have a frequency range that matches the head so you can run the EQ controls in the center for a solid neutral sound with enough range  to accommodate most popular guitar types.  If the amp tone is lacking in some area you can find the frequency chart on most speaker manufacturers site and get a boost of cut in the ranges you need. 

The loudness of the speaker is another important spec.  Wattage is only a power consumption number. Like a Fuse that number must match or be higher then what the head puts out to prevent it from blowing.  Beyond that its a useless number.  If you have a 50W RMS head a 50W RMS speaker is the absolute minimum wattage speaker you should use if you push that head to max which is full up on a SS amp or just below saturation on a tube amp (50 to 75% on the volume knob).  

The spec that tells you how loud a speaker is the SPL number.  SPL is and efficiency number like Miles per gallon in a car except it tells you how efficiently it converts electricity to speaker cone movement. Since that movement creates sound the standard measurements is to measure the speaker using 1 watt of power at 1 meter with a 1KHz tone being fed into the amp. This will produce a dB level on a loudness meter.

I mention all of this because most manufacturers post the SPL level in their web pages.  If you own a speaker that's say, 94dB you can double the perceived loudness of that amp by getting a 97dB speaker.  You can double it again with a 100dB and so on.  There are some speakers as high as 110dB but I cant say how good they might sound, especially with allot of bass.  You have to make the electromagnet stronger, speaker cone lighter and the surround more flexible to make it more efficient.  You can wind up with a speaker too flabby for bass tones if poorly designed.  On the other end, a speaker in the mid 80's range are typically used in Hi Fi cabs and given limited frequencies in the bass ranges.  They read a low SPL because they don't produce frequencies up in the 1K range very well because they are designed as bass woofers. They need a heavy cone so they don't distort with strong bass frequencies.  they aren't designed for guitars so you wouldn't want to use them for that.  Guitar speakers typically produce frequencies between 100Hz and 5K Hz.  Anything above or below will be rolled off.   

 

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5 hours ago, WRGKMC said:

I mention all of this because most manufacturers post the SPL level in their web pages.  If you own a speaker that's say, 94dB you can double the perceived loudness of that amp by getting a 97dB speaker. 

 

Not to quibble, but an increase of 10dB(A) SPL is generally considered to result in a doubling of perceived loudness, not 3dB. 

http://www.sounddeadsteel.com/what-is-a-decibel.html

A 3dB increase in SPL (sound pressure level) will result from a doubling of power (or a 3dB increase in speaker sensitivity / efficiency), and will result in a doubling of sound energy (and reduces the allowable exposure time by 1/2, as per the 3dB rule), but it won't result in a doubling of perceived volume.

A 100W amp isn't perceived by humans as being "twice as loud" as a 50W amp, given the same speakers... it's only 3dB louder, not 10dB. 

To quote myself... :0

So let's assume we have a speaker with a sensitivity of 90dB @ 1W / 1m and a power handling capacity of up to 100W. If we power that speaker with 1W of power, it will generate 90dB when measured at a distance of 1 meter. If we double that power to 2W, the SPL measurement will increase to 93dB. If we increase the power to 10W, then the SPL measurement will increase to 100dB, which is "twice the perceived loudness" when compared to 1W. So it actually takes ten times more power to give us a perceived doubling of volume level. 

https://www.harmonycentral.com/articles/guitar-and-bass-amps/wattage-speaker-efficiency-and-amplifier-loudness-r195/

While a 3dB increase in speaker sensitivity will result in a noticeable increase in perceived volume, he'd need a speaker with a 10dB greater sensitivity rating vs. his current one in order to result in a doubling of perceived volume from the same amplifier. 

 

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I stand corrected.  Power doubled creates a 3dB increase.  I don't know why I forgot that. 

Anyway the point about upgrading the stock speaker can often make a really big difference.

The cost of high quality speakers is dirt cheap and its a non invasive completely reversible mod that doesn't hut the amps value, in fact it can increase it in many cases. 

 

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A little late to the party, I still regularly use  G40V that I picked up used in 2010/2011.

 

The original valves didn't sound great and it had a Hartke 10" aluminium cone bass speaker for a somewhat spikey sound. Swapped the Chinese 6L6s for some Russian 5881s and the 12AX7 for a 12AT7 to drop the gain, plus an Emi Ragin Cajun speaker. I also partially closed up the back to leave it about 25% open at the top for air circulation and added foam inside to simulate a larger enclosure.

 

I really like the small size and slightly crazy volume levels this thing can manage - like a shrunken Boogie Mk1.  I built amps for about a decade for personal use, but this was so small, relatively light and convenient while having a decent tone that it's become pretty much all I use now.

Edited by Ancient Mariner
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On 1/29/2020 at 2:18 PM, Acidhouse said:

Thanks Phil.  That's good to know.  I will reach out to Pignose but their cs support was pretty bad for these when they were in production.  It would be great to ask Kager but he died about a year ago.

 

Two Piggies.jpg

I am wondering how you have your midst and presence so high in these pictures. Mine is way bright and midrangey, but also mine has 6v6s and has been revised, and I'm using single coil guitars.

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