Own guitar amp

Tamago

Based on a number of threads here, I felt inspired to make my own guitar amp for home use and my close friend has been needing a good woodworking project for some time now.

Now I am going to do small amps with single Class-A output stages, but, please note, I have the capability to make more of these, should the forum membership find them appealing and wish me to make more, or do custom amps to each musician's requirements.

I am having trouble finding the following components:

* Aluminium chassis
* Celestion Speakers (specifically looking for a Super 8 as its specs match what I am trying to achieve and fits within the cost constraint)

I am well aware of the limitations of a single EL34 output stage, but I feel that 8 watts RMS is more than sufficient for the home and for the beginner musician's pocket (as well as my own pocket, considering I have spent a shyteload of money recently on guitars and cables and other accessories)\

If you are interested I will post the design process here...

PS- yes I have been quiet on the forum. Been sick as a dog and had a medical procedure done last week. Don't even ask, it was THAT bad!

singemonkey

Jeez dude. Hope you're ok now.

I'm sure Matta will be able to tell you where to get these things.

AlanRatcliffe

Celestion are being imported by Tradelius in Durban (http://www.tradelius.co.za/). (031) 502-3080 - Speak to Ron Naicker, tell him I sent you.
I see they are not importing the Super 8, but they are bringing in the Valve 10, and that retails for R450 (ex-VAT).

TomCat

For the chassis are you looking for something pre-made or to your own design?

If it's your own design I can probably help you with the design and pointing you in the direction of a suitable manufacturer....

Tamago

TomCat wrote For the chassis are you looking for something pre-made or to your own design?

If it's your own design I can probably help you with the design and pointing you in the direction of a suitable manufacturer....

Hi there

Thanks for the interesting response first of all about the speaker. I will rather phone Tradelius direct and get that going, as I was expecting to pay over R800 for a speaker and that was rather a good price for what I consider to be a very fine speaker.

Now, the chassis, has always been a problem for me, which is why I stopped designing with valves in the first place. I can design it yes, I just don't have access to anyone who can do the bending and all of that. I am not able to do a Solidworks 3D or other type of drawing due to the fact that I don't have access to such CAD software.

For the electronics I am going to use a PC board, primarily to ensure that if someone asks me to build one of these amps for them, I can do it relatively quickly. Hand-built wiring just takes too long and is prone to error.

I went into my stash over the weekend, I discovered I have all the tubes for this design, plus enough as spares and to build a second unit.

I am not going to use a GZ34 rectifier here as I feel a full silicon diode bridge, with running the heaters on DC will produce a cleaner supply and eliminate hum out of the amplifier. I have done this before, I did a 12AX7 preamp for a CD player, and the results were remarkable as I recall.

PS: In my stash of tubes, I found a large number of 6J5, 6SN7 and 807 tubes, as well as an assortment of "magic eye" tuning indicators. I also found, two output transformers, rated at 15 watts, designed for KT66 push pull valves i.e. the Williamson Amplifier. If you are interested in them, let me know as I have neither the space, nor use for these tubes and transformers.

matta

Firstly, sorry to read about your op, hope you have a swift recovery time.

Tamago wrote For the electronics I am going to use a PC board, primarily to ensure that if someone asks me to build one of these amps for them, I can do it relatively quickly. Hand-built wiring just takes too long and is prone to error.

I've seen, and can testify to amps from the 50's that are in FULL working order, a couple dried caps, but working and SOLID... I've seen PCB amps that were built 5-10 years ago that have traces that are PAPER thin on cheap single sided boards, so they offer very little in the way of mechanical strength etc. Point to Point is still king when it comes to having a SOLID connection... sure there may be wiring errors, but THAT is a problem for the builder, not the end user, and not to be rude, IF you are worried about miss wiring you prob shouldn't be building the amps for mass consumption.

I applaud you for this, it is ground I've covered myself, if you look in other threads. The problem is if you go PCB you are going head to head with 90% of the other consumer grade amps out there, and in some cases they are dirt cheap, 5 Watters like the Laney Cub, Fender Champion 600, Epiphone Valve Jnr, all retail for under R3,500 or less... hard to beat that with a 'cheaper' PCB made amp.

Also have you HEARD the Super 8? Personally I think it is a terrible speaker, well at least compared to a Jensen C8R, but then it is double the price... but worth it to my ears. Also my suggestion, go for the 10", not an 8", a 10" just sounds better.

Tamago wroteI am not going to use a GZ34 rectifier here as I feel a full silicon diode bridge, with running the heaters on DC will produce a cleaner supply and eliminate hum out of the amplifier. I have done this before, I did a 12AX7 preamp for a CD player, and the results were remarkable as I recall.

Um, again, 90% of modern Chinese amps do the same thing, the Blackheart and Epiphone both have DC heater and ALL of them have silicon recs, the Blackheart though DOES internally have a 5V tap for adding a tube rec if desired, which I thought a nice touch.

As I do this for a living I've found it better value to MOD these Chinese amps into better amps for the price, I think at last count a fully modded Fender Champion 600 amp retails at just over R5,000, but that is TOTAL rework, new speaker, new output transformer, a Pentode/Triode mode, beefed up PSU, DC heaters, rework of the tone stack to Tweed era 5F1 with Mallory 150's and a new set of JJ Tubes... and it looks good to boot, a couple forum members have these modded amps.

I'm also working out mods for the Epi Valve Jr and the Blackheart Little Giant, which for me is the BEST value for money Chinese amp to date.

Either way I wish you well in this en-devour and am happy to answer any questions you may have.

Cheers

Matt

Tamago

Thanks

I have a hernia, so what is happening is, my intestinal contents is getting into my throat, and then causes severe infections in my ears and nose, and then I have to take antibiotics to clear it up leading to me having thrush so bad I feel like dying. I can't get any more time off work so I am waiting for my son to be born then I will make a plan to have the op done to fix the hernia...

Anyway, getting back to my amplifier:

Speakers: I have never heard the Celestion series, primarily because no-one I've met has them. All I am going on is advice given to me by my music teacher. I do know Celestion from regular valve radios, and they sounded really good.

Wiring: I have recently had to make stuff using point-to-point wiring, and I found that I was error prone late at night, due to deadlines and crap. I was just concerned about that, and the speed of assembly. I also have a lot of PCB mount valve bases, if you are telling me that point-to-point like the old tradition, is solid then by all means I will do it that way. I know it is solid, I was just concerned about speed of assembly. You see I design electronic products for a living so this production stuff dominates one's thoughts whenever you pick up a soldering iron. I've been designing commercial products for mass production for 10 years now so I've got certain habits, which are undesirable in some respects.

Rectifier: Simple solution is to put a base in for it, and then get an octal plug and fit it with two 1N5408 diodes inside. That way the user can either keep the plug, or put a GZ34 in if he or she so desires.

However, that said, I realize that it is cheaper to rework a Chinese tube amp, but I do feel that two notable characteristics come into play here. Firstly, some folks, like myself, would love a fully custom amp, secondly, some people feel more comfortable having a say in their equipment's design. I am also a big fan of locally made stuff, I believe we make far too little electronic products in this country, but that's just me. In my line of work, everything we do puts us up against the Chinese, it is something I've gotten used to, as I know many people would rather buy a local product as, no offense, Chinese made products have somewhat of a reputation of being, I dare say, junk!

AlanRatcliffe

I tend to think you have two choices when it comes to manufacturing an amp for sale: cheap, which puts you squarely in competition with the Chinese stuff or expensive "boutique" models which is a much smaller market (and a LOT fussier - corksniffers the lot of us ?). Anywhere in between and you lost a significant part of either market. But you probably know this already. ? I think that the only area that is not covered adequately locally is high quality, lower powered amps with normal speaker sizes (a la Dr. Z Carmen Ghia or Cornford Harlequin) and the same with pro features (Cornford Carrera). Once again, a smaller market

Unlike hi-fi or radio, the speakers in a guitar amp are very much part of the tonal equation - that's why Celestion have a dedicated range of speakers specifically for guitar. They are designed to colour the sound and each has it's own personality. In the case of alnico magnet speakers they can add a significant amount to the cost of an amp too. Also compromising on the speakers you fit will have an effect on the desirability of any amp - few would want a custom amp that sports the same cheaper speakers as the Chinese imports. A big downfall of many smaller amps is the size and quality of the speaker.

I'm also a fan of the P2P wiring - far more reliable in the long run, which any serious musician will take into account. More expensive and labour intensive, but far more desirable. PCBs are mostly a manufacturer's solution, not a musician's - cheaper, quicker and easier to build and with a limited lifespan that means you're not competing against your own product that you built 50 years ago.

I like the idea of a choice between solid-state and valve rectification. Most old school guitarists will prefer the sag from valve rectification, while many newer players (or those of us who like a lot of punch) will prefer solid-state. Ted Weber makes the solid state "Copper Cap" rectifiers that plug into valve bases and feature linear in-rush current limiting to simulate the gradual warm-up of a tube rectifier, which is easier on the other valves.

I am also a big fan of locally made stuff, I believe we make far too little electronic products in this country,

I'm right behind you on that one.

Chinese made products have somewhat of a reputation of being, I dare say, junk!

As with the Japanese and Korean stuff of the past that is changing. Quickly.

TomCat

One thing I have learned about building an amp for yourself is that function rules.....one has to ignore the cost of building the amp....i.e....building a decent amp for yourself should not be motivated by trying to save money. I could have bought a number of off the shelf amplifiers similar to mine at a much lower price.

The benefit for me was:
1. Can I do it....Will it work....
2. Being able to make a test-bench to try out all different combination's / design tweaks easily.
3. Make it look the way I would like an amplifier to look.....be different / individual etc...
4. Enjoy the learning curve, experience I gained doing the project.

Is what I created perfect...no.....but I can now tweak to my hearts content with something I now understand....

For me the project was a success, great fun and a wonderful learning experience. Would I do it again....absolutely.....

Edit.....BTW if you are looking for a Celestion 10" there is the Greenback 10. More expensive but worth the money.....

Tamago

I think that the only area that is not covered adequately locally is high quality, lower powered amps with normal speaker sizes (a la Dr. Z Carmen Ghia or Cornford Harlequin) and the same with pro features (Cornford Carrera). Once again, a smaller market

I fully agree, and is why I decided that when I am going to build this thing, I want to be able to at least be able to build more because I know, if it is a success people are going to ask me to make one for them. This has always happened to me, I've actually sold many amplifiers over the years that I built because when you make one, then the folks come "hell that sounds damn good, can't you make me one..." And I cannot say no.

With finances as tight as mine (I actually do odd jobs for people to fund my musical endeavours, for instance the Squier I bought the other day, was paid for using cash I made doing a production run of PC boards at home) I tend to try and accept any work I can find.

That said however, you need to set some sort of realistic limit. I could go and have an OPT custom made, at over R1k, but I have decided to do the best I can with limited funds and components, that is the true art of engineering. Getting the best you can out of your limited component resources.

I want a tube amp, because I have a small 10 watt solid-state one, and I can tell you now, I don't like the sound one bit. It has far too much gain, is way too "bright". At school, I play with the Marshall amp they've installed there, that sounds so much better.

Attila

When chatting to JP Le Roux, the other day he said that he can get 25w Celestion Greenbacks @R1500 each immediately for those interested I think that is a fair price

I tend to agree with Alan Dr Z's Carmen Ghia and Route 66 are briliient amps because of thier simplicity... BTW Should anyone want BOM and build info..... let me know I may just have something for you. :?

I like the idea of a Class A single ended power stage with self biasing, that can handel various tube plugins for recitfication, pre amp and power - ala Emery Sounds Superbaby etc.

Tamago

Thanks for the info Attila ? Much appreciated.

I also like Class A amps, as the output stage is quite elegant. Sure it is not what you would use for that rocking loud performance, but I feel that, you can put it to great effect in a domestic setting. I can tell you now I am sure I can push an EL34 to give me a really great tone. The last time I did that was in 1994, I am currently busy tearing my study apart for the schematic and hand drawn notes I made from back then.. At least I found the book with my preamp circuits in them ?

AlanRatcliffe

Attila wrote When chatting to JP Le Roux, the other day he said that he can get 25w Celestion Greenbacks @R1500 each immediately for those interested I think that is a fair price

He should be able to get the Classic 30, Classic Lead, G12T-75, and G12M, all at that price or slightly less (ex VAT, but retail - before discount). Some of the cheaper ones are also available, as are the Blues (at a price). Golds and anything else are special order.

Tamago

Thanks for that interesting bit of info. I am even more confused now as to choice of speaker, but what could help is if we could summarize here which of those speakers are good for which kinds of applications, that would help a lot.

Attila

Tamago,

I dont know what Celestion do but Jenson has a " sound check demo" for thier various speaker types and sizes and ratings, on thier website.

matching your amp to your speaker is IMO the most essential part, because your amp is tweekable to your likings unlike your speaker which is predefined in its construction

Tamago

That is true

For my own amp, the plan is to get a particular speaker and optimize the output stage and OPT to the speaker. That's the best I can think of doing at this point in time.

Attila

Spoke too soon check out

http://professional.celestion.com/guitar/features/tone/index.asp for guide lines and sound check quite cool

AlanRatcliffe

Each manufacturer has info on each speaker. The difficulty with spec sheets and manufacurer's info - as usual - comes with comparing models across brands and knowing how each sounds with each different type of amp design (and especially with predicting how it will sound with a new amp design). After many thousands of hours testing speakers, I've narrowed it down a bit, but it's still a whole ton of information and there is tons I don't know. For commercial applications, my consulting services are available for a modest fee. ?

Otherwise it's do what every other amp designer does - build your amp, buy a whole whack of different speakers and try them until you find ones you like.

Tamago

Thanks Alan

What I will do then is get the amp working and stable, and use my instrumentation to get the best performance possible sonically, using techniques I've taken a lifetime to learn.

Then I will purchase various loudspeakers and see which sounds the best. Of course we need to always bear in mind this is all subjective. I can tell you now, a certain amp/speaker that might sound cool to me in the morning, I will detest late at night.

matta

Tamago wrote Then I will purchase various loudspeakers and see which sounds the best. Of course we need to always bear in mind this is all subjective. I can tell you now, a certain amp/speaker that might sound cool to me in the morning, I will detest late at night.

That is why you need to put it in the hands of other players and let them decide... Tone is subjective, so get feedback from your potential market, since they are the ones feeding you ?

Matt