General improvement of a mass produced amplifier

[JacksonRR]

What I'm looking for is what have you guys done, without changing values if possible, to your amps. Just swapping stock components for a higher grade/type. Your favorites, go-tos... Stuff like that. You know just pokin around in your spare time making little fidelity and cutting noise improvements kinda stuff.

[Chuck H]

Considering that part values often fall in the +/- range of 20% for assembly line amps there will nearly always be a value change. But to answer your question I would say that you can get a substantial improvement in most "budget" or "affrordable" assembly line Chinese amps by changing the speakers and tubes. After that it's the transformers. Not a coincidence that these are the most expensive parts in the amp, and further, even more expensive to replace a la carte. The parts your replacing have essentially NO value on the resale market so it's $400 to $800 for the amp, another $100 to $150 for the speaker, $100 for tubes and $200 to $300 for transformers. Top end filters and other components would naturally follow. While requiring the greatest amount of work to replace the actual caps and resistors do represent the last maybe five % in tone refinement. In the end if you want to approach what you would get with a "boutique" amp you'll be into it around $1200 to $1500 plus two days of labor (probably worth about $500 ro $600 for the average Joe), so now your into a PCB Chinese import turd for $1700.00 to $1900. You may be better off buying an actual boutique amp from a skilled craftsman and enjoying the product support and expertise that comes with this kind of purchase. Not to mention that the final product has already passed muster, will sound fabulous and hold a better resale value.

If the last ten % of tone that's possible is important to you, bite the bullet and buy a boutique amp. If you can live with ninety % buy a Fender Hot Rod or Peavey Classic series amp and just play your guitar. These are the best sounding and most affordable amps on the market IMHO. If your a head banger on a budjet I'm not sure where the best value's are.

All this amounts to MHO of course.

[Steve Conner]

I've never bought a mass-produced amplifier, I wouldn't know.

[JacksonRR]

Thanks for the info Chuck. I should have named the thread Recreational improvement. I don't have anyone to impress except myself so a manufacturer name is nothing. I actually don't have any chinese amps here with me right now. Just a few Peaveys and a Laney. The Laney is horribly made. Cold joints all over the place. Just got it a few weeks ago. Had some issues that are resolved now. That's the little bastard I'd like to do weekly surgery on just for kicks. I got some good replies a few days ago on another forum, wanted to see if your guy's info matched up. Much different response here.

[guitarmike2107]

Although I have bought some mass produced amps, they are all sitting at the bottom of a cupboard untouched.
I only pull them out occasionally to hear just how much better my own amps sound.

I have changed speakers etc, but if you are going to start replacing the OT, the speaker, the valves etc you (I) may as well build an amp that does exactly what you (I) want

[MWJB]

I guess that there are a couple of ways to look at this...

Some guys buy cheap amps as a platform for modding, conceding prior to purchase, that they are probably not going to be the epitome of tone to begin with. They want something that they can practice a bit of soldering & rewiring on, without screwing up a $1000+ amp and are never going to make warranty claim. If you're going to be doing the work yourself, then you are probably going to charge yourself a very reasonable rate & parts are going to be the only tangible outlay...the world's your oyster, you get some practical experience, possibly improve the tone of the original amp & accept the fact that you have the world's most expensive Champion 600/V Jr/(insert $100 amp of choice) and no chance of recouping costs at resale. It's all good.

Moving up to more practical situations, like a mid priced stage amp, I'd look at retubing & a bias adjustment...if it has a low count on speakers, then possibly sub them (4 new alnicos can cost upwards of half an amp's original value). Beyond that, if you're not happy, changing all the caps for "foil in oils", replacing the PCB for an identical hand wired circuit & all the electrolytics for Spragues is going to have relatively little impact for a considerable outlay in terms of parts & especially labour...so if the retube & possible speaker sub doesn't get you 95%+ the way to Nirvana...stick the old parts back in & shift it on for minimal loss at resale.

As Chuck intimates, you can change what you like, but it won't affect resale. What you going to do when 3 similar amps all show up on e-bay at the same time as yours, for half the price your asking.

Most boutique amps seem to end up in the hands of keen hobbyist, empty nesters...for kicks at home & bragging rights. There will be some that are sold to guys who have a specific thing in mind, in this case most boutique manufacturers are flexible and seem happy to make certain changes on request (upcharges may apply), if still not happy at delivery, most seem happy to at least provide suggestions on changes to suit the customer, if return to the factory is impractical. Most want a happy customer at the end of the day.

In short, beyond making sure that the amp is working as it should & that the tubes are a brand that you are happy with (most manufacturers fit whatever they can buy at the lowest price - but that doesn't instantly mean that the tubes are obsolete, even the cheapest tube can sound magic in the right environment) modifications should be considered in relation to a specific goal/purpose & stand up to comparison with a "known good" model, rather than the arbitrary installation of parts from what are perceived to be "desirable suppliers". I'll stick my soldering iron in any amp that comes my way, I don't care who built it, or what their rep is (I know what it's like to blow your savings on the world's prettiest "doorstop", every pitiful sounding note feeling like another nail in your coffin)...I just want the owner to be able to quantify what they want more/less of & be confident that the mods performed will deliver. The brand name on the part means nothing if the part is the wrong value for what you are trying to achieve.

I often hear, "Can you help me, I just bought a (insert $300-$500 amp of choice) but it doesn't sound as good as my favourite player through their (insert boutique/vintage amp of choice)?" Well, I'd start by taking out the tubes, then the speakers, the caps, the resistors, the transformers, the chassis, then the cab. When they're all safely in the landfill, GO AND BUY THE AMP YOU WANTED IN THE FIRST PLACE! Play through the amp before you buy it, not a similar model...it's a good idea to compare side by side with your current rig first.

[R.G.]

I've done a lot of electronic building over the years. I find the electronics simple. What's HARD is doing the woodworking to build a cabinet, the metalworking to make a chassis, etc.

I personally view buying a no-name amp which is easy to modify as a great bargain. I got a 100W 2-12 no-name SS combo locally for $40. No way I could build a cabinet and chassis and make it cosmetically acceptable for that, not to mention how long it would take me to do the cutting and forming. Note that getting a SS amp lets me cut tube socket holes anywhere I want because only small board mounting holes go in the chassis on SS designs. This one is getting the guts of the UK Vox Defiant put into it. I can toss away the speakers as useless, or use them for bench testing "victims".

[imaradiostar]

I'm with RG on this one- I have a few small solid state combos that I ended up with for free. They're excellent for trying amp ideas. I used a marshall valvestate chassis with a toroidal PT and a vibroverb output to build an inexpensive amp for a friend of a friend. All the components are inside the large steel chassis and it turned out pretty nice.

If you gut the old solid state PCB you're likely to end up with a bunch of small pots that are ideal for pedals. I use the inexpensive but smooth feeling large alpha pots from mouser in my amp builds- they'll still fit on 1" hole centers if needed but I've found them more reliable than tiny pots at tube amp voltages.

The main point of this is to say- I've found a simple single channel tube amp is generally much more satisfying to play than a generic multi-channel super amp built with bargain components. Assuming the speaker and cabinet are decently made, any simple tube amp (think early Fender, Marshall, or modern Dr. Z) would be an interesting use of a chassis.

I just remembered- in college I built a 50 watt plexi in a peavey chassis for a friend. Good fun. I wonder if that amp is still in use?

jamie

[R.G.]

I like to think of building a tube amp into an old solid state chassis as a "soul transplant" 8-)

[JacksonRR]

Ok. I'm gonna make the decision to not engage in this activity. It seems that even though there are things that could be done, there is nothing that should be done. I already know how to solder and have no goal in mind or anything to gain so it's to the garbage with this idea. I guess I have to remodel my living room now.... I hate painting so very much. Maybe I should remodel my studio room instead. Yeah, that'll get me some sex. I'll do that. =) Thanks for talking me off the ledge.

[Steve Conner]

Lol... You do that, and I'll fix the bathroom floor. Been putting that off for long enough.

The modding scene is a little crazy. Swapping out components for other ones of the same value but a higher grade doesn't really do anything, except maybe OTs and tubes. It's not that different to putting 18" wheels and a huge spoiler on your Civic, and then acting all surprised when it actually goes slower than stock. Although I have been tempted to buy the Mercury Valve Jr. transformer kit and build an amp from scratch around it.

When it comes to modding the electronics, topology (that is to say, the arrangement of the components) is the most important thing. If you remove a gain stage, add an extra one, change the tone stack to a Baxandall, you're going to notice that all right.

The next most important thing is component values. Changing cathode bypass caps, feedback resistors, swapping 12AX7s for 12AT7s and so on.

Compared to these, the brands of components hardly matter at all. But it doesn't require any knowledge of electronics to change all of the capacitors to Sozos.

One mod that's always worth it is trying a different speaker. It's so easy to swap the speaker out, and it's probably the part of the amp that has the greatest effect on the tone. It doesn't hurt the resale value, because you can save the old one and put it back in. It may even help, I'd probably pay a bit extra for an amp if it had a Celestion Gold in it.

And as someone said above, the low and mid-priced amps never come with really good ones, though I guess the Marshall 4x12s with their Celestion G12T75s were an exception. There's a Rivera speaker shootout movie somewhere on YouTube that makes interesting viewing: all of the speakers have completely different tones.

[Pedro Vecino]

http://www.youtube.com/watch?v=jWK0sa7tlfI
Different tone but same texture

[JacksonRR]

Is this what they mean when they say dripping with tone? YouTube - Non-Newtonian Fluid on a Speaker Cone

[JacksonRR]

Speaking of Baxandall, I am building a clone of the Xotic RC Booster. Pretty much a tubescreamer with a Baxandall EQ. That's another forum though, I guess.... Yeah I hear ya on swapping components taking no background or understanding. Thought if I was good on the circuit, a boost in component quality would do a LITTLE something.

[R.G.]

Thought if I was good on the circuit, a boost in component quality would do a LITTLE something.

That brings up a good point. "Quality" is an elusive thing to measure.

It's easy to think that a higher quality component is somehow better in all respects. "Mil-Spec" is one example of what gets tossed around for "higher quality". I was somewhat amazed to find out that "Mil-Spec" logic is often ...slower... than commercial grade logic, or was back when logic was done with TTL chips. The extra "quality" was in the fact that it would take wider power supply and temperature variations and keep on working within it's more-relaxed speed specs. For the military, "more rugged and tolerant of environmental variations" was what "higher quality" meant.

Until you can define what you mean by the word, "quality" is much like "beauty" - it means nothing in particular. All by itself, it's only good for advertising.

I was forced through the grinder of product quality eductaion back when it looked like Japanese manufacturing would eat up the world because they were the only country that could consistently produce stuff that worked as expected. How things have changed - but that's another story, I guess. Anyway, the best definition of the word quality in isolation from any particular specifications is "conformance to specifications". If something meets all of the specifications for the things, then it is of high quality. Logically, if you have no specifications (reduces to: you don't have a clear idea what you want) then all things are of equal quality.

It is very much a characteristic of the human mind to think that there must be tiny differences in otherwise-equal things, and that one may be somehow better than another. But that can be a very slippery slope, leading to circular "increases in quality" as you experiment.