DIY Valve Amp Kits

[pfretrock]

[quote name='Beer of the Bass' timestamp='1426109649' post='2714619']
The toroidal mains transformers from TubeTown in Germany look like good value and would help keep the weight down too. [url="http://www.tube-town.net/ttstore/index.php?cat=545&sort=3&MODsid=3h1dg232ltdautadajuah9e8k5&sort=7"]http://www.tube-town...uah9e8k5&sort=7[/url]
[/quote]

I got one from Ampmaker, low enough to hide under the chassis, more room to show off the valves up top. little stray magnetic field. Pity there is no torroidal ouput transformer. (AFAIK). Ugly things, transformers.
Home build is Ok up to 18W, gets expensive and scary high voltages beyond that.

[JapanAxe]

[quote name='pfretrock' timestamp='1426162233' post='2715049']
Home build is Ok up to 18W, gets expensive and scary high voltages beyond that.
[/quote]

There's up to 340V DC on the board on my 5W single-ended amp - that's scary enough!

[Beer of the Bass]

[quote name='pfretrock' timestamp='1426162233' post='2715049']
Home build is Ok up to 18W, gets expensive and scary high voltages beyond that.
[/quote]

I would never suggest starting out with a higher powered amp, but personally I'm no less cautious working with 200v than with 500v, as I do not want to be shocked by either! I guess it's a question of assessing what you feel competent to work with. For me, something of SVT size and complexity would seem overly ambitious, but I'm confident I could safely and successfully build a simpler, classic 30-100 watt fixed bias design, not deviating too far from established layouts.

[Bottle]

I'm leaning towards the 4W WN55 build and I'll get some help from my Dad to build the head casing. I'm thinking of adding the passive tone stack as well. Looks like Barry is off on his holidays until the beginning of April anyway (and I have no money until the end of the month too!)

So I'll report back once the kit is in my hands thanks for all the advice so far - it's all been very informative!

Cheers!

[stevelee]

Hi another fan or barry at Ampmaker here.
Not cheap kits but good value, good instructions, and support if req.

Not sure if anyone has alreay mentioned this site- its a great place to start if your thinking of building valve amp
[url="http://www.ax84.com/"]http://www.ax84.com/[/url]

[Bigwan]

Probably not the best place to be asking this but since there's other DIYers here I'll give it a shot. I've been looking at a few bits and pieces over the last few days and have (VERY) quickly cobbled together 2 partial schematics from an Ampeg B25 and a line driver output from the Gyraf G9 valve preamp. Can anyone see anything fundamentally wrong with this as a starting point for experimenting with? Obviously no PSU design here but I'm looking at bassing it (see what I did there) around Barry's/Ampmaker's toroidal transformer. I'd be looking to add an unbalanced output and a level control for the XLR (probably by putting a pot between the 2 hot outputs).

[URL=http://s38.photobucket.com/user/Bigwan2062/media/preamp%20idea.png.html][IMG]http://i38.photobucket.com/albums/e136/Bigwan2062/preamp%20idea.png[/IMG][/URL]

Edited March 18, 2015 by Bigwan

[Beer of the Bass]

One thought on that; you may want to use a higher value pot than 47K for the output level, as the output of these preamps apparently works better when run into a high impedance input.

[Bigwan]

I'd thought about that, 500k or 1Meg probably be better values. I'll play around with the location of the tonestack as well as the tonestack values, but wanted this as a starting point to try the ultra switches out - ultra high might be better across the 2nd level control instead. Also want to try a few mid control ideas, shift control in place of the 120k in the tonestack, etc. Doubt I'll go as far as an inductor based mid circuit like the svt, but you never know!

[pfretrock]

[quote name='Beer of the Bass' timestamp='1426678951' post='2720595']
One thought on that; you may want to use a higher value pot than 47K for the output level, as the output of these preamps apparently works better when run into a high impedance input.
[/quote]

Agree.

On the power supply side, Barry's smaller unit does not have a centre tap heater - this is usually grounded to kill 50Hz hum. But you can add a low value pot across the heaters and ground the wiper. Adjust pot for minimum hum.

[Bigwan]

[quote name='pfretrock' timestamp='1426681208' post='2720640']


Agree.

On the power supply side, Barry's smaller unit does not have a centre tap heater - this is usually grounded to kill 50Hz hum. But you can add a low value pot across the heaters and ground the wiper. Adjust pot for minimum hum.
[/quote]

I'd planned 2 100ohm resistors as a faux ground, but a pot would be a better idea!

[b7l4s]

Another +1 for Ampmaker from me. I built an SE-5a a couple of years ago and it was a really well thought out kit, plus it sounds better than it has any right to given my level of skill with a soldering iron. I was only thinking recently that if Barry did bass amp kit I'd definitely be looking to buy it.

Doing the build did lead me to a lot of reading and research about the science (or black art) of valve amp design, which I also got a lot out of. Whatever way you choose to go, you do get a lot of satisfaction from playing though something you built yourself. Just make sure (twice at least) that you have got everything right before pluggint it on to the mains for the first time - like people have already mentioned there are dangerous amounts of electricity involved.

[jensenmann]

@Bigwan
Why don´t you built the entire G9 sans mic-input/phantom circuit? This is the best bass DI I´ve ever used and I own many, even big name and big $$$ ones. The G9 has outperformed all of them. It´s output has app 1,2k output impedance and can easily drive most EQ circuits - no need to mess with the circuit by installing an interstage EQ.

I´ve DIYed the Madamp BP1 a few month ago. The kit was incomplete, with some faults in the documentation, some parts didn´t fit and the mains tranny was defective. Not that great if you´re a beginner in DIY-land (which I am not). After having sorted all that out + some mods and tweaks to the circuit it turned out as a nice bass preamp. But it couldn´t hold a candle to the G9!
This convinced me to build another version of the G9 as a basspreamp in PTP. Since it has no EQ I´ll add an AMEK M2500 EQ which I have sitting in the corner and pre/post EQ DI outs.

[Bigwan]

[quote name='jensenmann' timestamp='1426880895' post='2723163']
@Bigwan
Why don´t you built the entire G9 sans mic-input/phantom circuit? This is the best bass DI I´ve ever used and I own many, even big name and big $$$ ones. The G9 has outperformed all of them. It´s output has app 1,2k output impedance and can easily drive most EQ circuits - no need to mess with the circuit by installing an interstage EQ.

I´ve DIYed the Madamp BP1 a few month ago. The kit was incomplete, with some faults in the documentation, some parts didn´t fit and the mains tranny was defective. Not that great if you´re a beginner in DIY-land (which I am not). After having sorted all that out + some mods and tweaks to the circuit it turned out as a nice bass preamp. But it couldn´t hold a candle to the G9!
This convinced me to build another version of the G9 as a basspreamp in PTP. Since it has no EQ I´ll add an AMEK M2500 EQ which I have sitting in the corner and pre/post EQ DI outs.
[/quote]

The thought of building a single channel G9 had crossed my mind, but I figured the Ampeg preamp would better suit the sound I'm going for. Nothing to stop me trying both, other than a serious lack of free time!

[Bottle]

[quote name='b7l4s' timestamp='1426693821' post='2720908']
Another +1 for Ampmaker from me. I built an SE-5a a couple of years ago and it was a really well thought out kit, plus it sounds better than it has any right to given my level of skill with a soldering iron. I was only thinking recently that if Barry did bass amp kit I'd definitely be looking to buy it.

Doing the build did lead me to a lot of reading and research about the science (or black art) of valve amp design, which I also got a lot out of. Whatever way you choose to go, you do get a lot of satisfaction from playing though something you built yourself. Just make sure (twice at least) that you have got everything right before pluggint it on to the mains for the first time - like people have already mentioned there are dangerous amounts of electricity involved.
[/quote]
Got in touch with Barry as he'd been on holiday for the whole of March. He's been very helpful and we discussed all the options I wanted to add on to the basic kit. Went ahead and ordered the WF-55 so it should be ready on Monday! Woohoo! I'll update this thread with a Build thread once I have the kit and all the gubbins to go round it.

Cheers to everyone for their input into my decision-making process


Ian

[Ancient Mariner]

Nice one - should be a fun build.

Recently I acquired a Marshall MG30 cheap because it was failing, so planned to gut & build a valve amp into the chassis like I did years ago with a Vox pathfinder.



Anyway, some time in 2008/9 I'd put together an amp design that borrowed all sorts of 'good ideas' from other people on the Watkins and AX84 forums, including a cascode preamp, switchable clipping LEDs and baxandall low loss tone stack into a single ended power stage that would use anything from a 6V6 to a 6550 for between 6W and 20W. Like all good ideas, it didn't work, and after spending hours trying to find the fault I gave up and stored it away for when it might get re-purposed.

So the plan was to use this to become the donor amp, stripped and returned to a 'standard' configuration, probably an AX84 P1eX based design like Voxy baby had been. So I started stripping last night and, amazingly, the second wire I started to remove had a failed joint and turned out to be the source of the problem all along. 30 sec with the soldering iron and suddenly my project amp works, and sounds great! Now I'll have to consider whether I want to do the transplant using these bits (that is NOT a Marshall sounding amp - really chimey) or build something more specifically marshally. I'm really pleased about this.

[Dad3353]

[quote name='Ancient Mariner' timestamp='1428862275' post='2745410']
Nice one - should be a fun build.

Recently I acquired a Marshall MG30 cheap...
......
I'm really pleased about this.
[/quote]
[sharedmedia=core:attachments:166776]
Excellent..! I like stories such as this. Serendipity..? Fatalism..? Pot luck..? Spooky..!

[Bigwan]

Nik at ceriatone is working on a single channel, small format ("lunchbox" as he calls it) B15 clone, final spec still to be settled. Their amps are usually available as kits so I'll be looking forward to that. He's said it'd be a little more expensive than his OTS Lunchbox (mini dumble), so I'd guess somewhere in the $400 region for the kit without valves or headshell, or $800 for a complete head.

Edited April 17, 2015 by Bigwan

[JapanAxe]

[quote name='Bigwan' timestamp='1429301333' post='2750319']
Nik at ceriatone is working on a single channel, small format ("lunchbox" as he calls it) B15 clone, final spec still to be settled. Their amps are usually available as kits so I'll be looking forward to that. He's said it'd be a little more expensive than his OTS Lunchbox (mini dumble), so I'd guess somewhere in the $400 region for the kit without valves or headshell, or $800 for a complete head.
[/quote]

Ooh! Fun project!

[jensenmann]

[quote name='Bigwan' timestamp='1426882457' post='2723192']
The thought of building a single channel G9 had crossed my mind, but I figured the Ampeg preamp would better suit the sound I'm going for. Nothing to stop me trying both, other than a serious lack of free time!
[/quote]

In the meantime I´m a bit further with my DIY basspreamp quest. The BP1 finds no use anymore. I´ve perfboarded a 3 stage FET preamp with with the intention to simulate the Bassman 135 preamp wit FETs. It has one volume control and a bright switch with 5 frequencies which sounds nice. After fiddling with a tonestack which I didn´t like I finally added a trusty workhorse EQ which I know very well from my studiowork. It´s a DIYed API553-stylee 3 band swinging input EQ. For techies: It´s inductor based, low and mid band proportional Q bell filters and a shelving HF filter. All bands have 3 switchable frequencies which are optimized for my basses. Finding the good sounding frequencies took 10hrs alone... The output stage is a Melcor DOA driving an API 2623 transformer.
Here´s some porn, inside: [url="http://www.directupload.net/file/d/3985/fqao7pgu_jpg.htm"]http://www.directupl...qao7pgu_jpg.htm[/url]
Outside, the one with the silver frontpanel: [url="http://www.directupload.net/file/d/3985/k8mifzzz_jpg.htm"]http://www.directupl...8mifzzz_jpg.htm[/url]
No tubes, sorry....

The single G9 PTP Basspre is in the works, too. The layout and most of the drillwork is done, turretboard stuffed... Pictures to follow...

Edited May 22, 2015 by jensenmann

[Bigwan]

[quote name='jensenmann' timestamp='1432325372' post='2780599']


In the meantime I´m a bit further with my DIY basspreamp quest. The BP1 finds no use anymore. I´ve perfboarded a 3 stage FET preamp with with the intention to simulate the Bassman 135 preamp wit FETs. It has one volume control and a bright switch with 5 frequencies which sounds nice. After fiddling with a tonestack which I didn´t like I finally added a trusty workhorse EQ which I know very well from my studiowork. It´s a DIYed API553-stylee 3 band swinging input EQ. For techies: It´s inductor based, low and mid band proportional Q bell filters and a shelving HF filter. All bands have 3 switchable frequencies which are optimized for my basses. Finding the good sounding frequencies took 10hrs alone... The output stage is a Melcor DOA driving an API 2623 transformer.
Here´s some porn, inside: [url="http://www.directupload.net/file/d/3985/fqao7pgu_jpg.htm"]http://www.directupl...qao7pgu_jpg.htm[/url]
Outside, the one with the silver frontpanel: [url="http://www.directupload.net/file/d/3985/k8mifzzz_jpg.htm"]http://www.directupl...8mifzzz_jpg.htm[/url]
No tubes, sorry....

The single G9 PTP Basspre is in the works, too. The layout and most of the drillwork is done, turretboard stuffed... Pictures to follow...
[/quote]

Good work!

Looking forward to seeing your ptp G9 when it's done!

[tonewheels]

I've been building and modifying valve guitar amps for the last 20 years. Not enamoured of most of the UK DIY kit firms because they tend to concentrate (quite understandably) on Bassman architecture amps with British (EL84 or EL34) valves. Fine for heavy metal and weedy as hell for bass (ironically) but not really for me.

I've just moved from a '70s SVT/8x10 rig to a Barefaced/GK setup but would still like to have a pure valve option. So I'm looking to a 200W, 4 x 6550 design, passive high impedance tone stack (not that horrid CF Bassman/Marshall thing - don't know quite why but it seems to suck bottom end) in a 17" cabinet so It doesn't look dumb on top of a 1x12".

The most expensive part is going to be the iron. Unfortunately the market is populated by chancers. Hammonds are expensive to import. The major UK firms take the piss because they're ripping off the Hi-fi gullible. I used to use Ripley Transformers who were fantastic, doing custom iron to any spec for less than half the price of the UK's leading off the shelf brand. Unfortunately they seem to have retired. And, of course, you needed to know how to spec the transformers (download the Radiotron Designer's Handbook for this).

So, anyone know a decent transformer supplier?

Anyone interested in a joint project?

[jensenmann]

My custom trannies are done by German company [url="http://www.mueller-rondo.com/produkte.htm"]http://www.mueller-rondo.com/produkte.htm[/url]
They are very good with torroidal stuff and are willing to wind single custom items.

[Subthumper]

Don't know how good they are but the Inmadout transformers from Italy are very reasonably priced. In particular they do do complete sets for the 100, 200 and 400 hiwatt amps, plus numerous fender marshall copies. Should hopefully be getting my hands on one soon so should be able to see what the quality is like. I built all my amps using recycled iron but in the future would prefer to use brand new as its impossible to know what's happened to a piece of kit over the years. Prices certainly get high once you pass the 100watt mark.

[LukeFRC]

[quote name='jensenmann' timestamp='1432325372' post='2780599']
In the meantime I´m a bit further with my DIY basspreamp quest. The BP1 finds no use anymore. I´ve perfboarded a 3 stage FET preamp with with the intention to simulate the Bassman 135 preamp wit FETs. It has one volume control and a bright switch with 5 frequencies which sounds nice. After fiddling with a tonestack which I didn´t like I finally added a trusty workhorse EQ which I know very well from my studiowork. It´s a DIYed API553-stylee 3 band swinging input EQ. For techies: It´s inductor based, low and mid band proportional Q bell filters and a shelving HF filter. All bands have 3 switchable frequencies which are optimized for my basses. Finding the good sounding frequencies took 10hrs alone... The output stage is a Melcor DOA driving an API 2623 transformer.
Here´s some porn, inside: [url="http://www.directupload.net/file/d/3985/fqao7pgu_jpg.htm"]http://www.directupl...qao7pgu_jpg.htm[/url]
Outside, the one with the silver frontpanel: [url="http://www.directupload.net/file/d/3985/k8mifzzz_jpg.htm"]http://www.directupl...8mifzzz_jpg.htm[/url]
No tubes, sorry....

The single G9 PTP Basspre is in the works, too. The layout and most of the drillwork is done, turretboard stuffed... Pictures to follow...
[/quote] love the EQ! I used to have the Warwick Hellborg preamp and been tempted to do a build based around a API 312 (possibly just for bass so without the input transformer) - was wondering if I would build an EQ too and your post has inspired me! Liked looking at the G9 preamp too- not found that before.

[Pentode]

[quote name='jensenmann' timestamp='1426880895' post='2723163']
I´ve DIYed the Madamp BP1 a few month ago. The kit was incomplete, with some faults in the documentation, some parts didn´t fit and the mains tranny was defective. Not that great if you´re a beginner in DIY-land (which I am not).
[/quote]

Just out of curiosity, what was the problem with the mains tranny?

Thanks
Grahame