[digger945]

Looks great ludoo. Love those Obbligato's. You got a secret stash of Silmic II's?
Good to see you guys enjoying this amp, I knew you would really like it a lot. I got some strange looks at the recent meet when I said the output on the aikido was 4 voltage regulators. Never would believe they could sound so good.

 

[ludoo]

Quote:

Originally Posted by digger945 /img/forum/go_quote.gif Looks great ludoo. Love those Obbligato's. You got a secret stash of Silmic II's?

LOL no, I just found a great and reasonable online seller in Germany who carries lots of nice stuff, including the Silmic II. And I don't get why in a simple amp like this many people go cheap on the caps: when you factor in all costs, boutique caps are maybe 2% or 3% difference on the total.

Quote:

Good to see you guys enjoying this amp, I knew you would really like it a lot. I got some strange looks at the recent meet when I said the output on the aikido was 4 voltage regulators. Never would believe they could sound so good.

I am liking it quite a bit, it's definitely more detailed and musical than the SS and costs about the same (and is much easier to build). The only minor thing is it starts distorting at about 75%-80% volume, which is loud but still reasonable with the hard to drive HP-3 I am using. I will probably try to add bypass caps for the cathode bias resistors to try and get some more gain. If I had the money and time for a larger build, I think the Aikido would be my choice.

 

[Nemo de Monet]

Quote:

Originally Posted by ludoo /img/forum/go_quote.gif And I don't get why in a simple amp like this many people go cheap on the caps: when you factor in all costs, boutique caps are maybe 2% or 3% difference on the total.

There's this tendency to think cost + complexity == quality, which I think this amp shows isn't true. But also I think you have to keep in mind that a goodly number of popular DIY amps, in particular, have been designed and marketed as "second best" versions of bigger, more expensive, more complicated, and "better" amps, and still more have ostensibly been designed to be first and foremost cheap to make; as such, some people don't see the point in putting "good" components in something that doesn't "deserve" it. (I think it was over on the other forum, but someone a long time ago made some disparaging remark about putting boutique caps on an AlienDAC, saying something to the effect of 'why put high-octane gas in a Geo Metro? it's never going to go fast, no matter what you do to it'.)

That said, there's a big difference between boutique and, you know, gold-plated-fairy-wings-in-unicorn-blood boutique. Sure, Obbligatos and Elnas are "boutique", but it's not like we're talking about Jupiter or Mundorf levels of "boutique", here.

Quote:

I am liking it quite a bit, it's definitely more detailed and musical than the SS and costs about the same (and is much easier to build).

I don't have a SS, but after a while listening to this amp with a decent power supply, I'm finding it more enjoyable than a SOHA Mk. I with JISBOS. Which saddens me quite a bit, because I have a lifetime supply of 12AU6-family tubes stashed away.

...and, needless to say, it's a lot easier to build than a SOHA Mk. I, as well.

Of the tubes I've tried so far - GE, Sylvania, and RCA 6AU6; JAN Philips 6922 - I'm really, really liking the Philips 6922; once it burned in a bit, it's really, really nice. I haven't done any RMAA tests, and don't really plan to, but my impression is that it may be a bit more linear than the other tubes I've tried. To my ear - and this may just be me - none are lacking even the slightest in bass, and all reproduce highs quite well, but some - particularly the Sylvania - emphasize mids and vocals; I don't find this objectionable at all, as I rarely listen to instrumental music, and actually like to hear what people are singing - but the Philips 6922 seems to have less emphasis here than any of the other tubes I've tried.

 

[DKJones96]

I've now got about 30 hours on my amp and I can say I'm happy with it. I've only been using my computer as a source for most of it since I kinda forgot two resistors to finish my bantam(oops), but I can say I've gotten addicted. I've been reluctant to continue use as constant as I really would like the fan installed and the cover done before I start using it daily. I'm pretty sure I'm within the safety margin for the chip but I don't like any electronics being hotter than i can hold my finger on.

I think the success in this amp lies in its simplicity. Input cap -> tube -> fets -> output cap, that's it.

 

[kansei]

I'm halfway through building the second one. Currently missing 4 resistors, the 13 and 15 ohm ones. I'm considering putting in a 20 ohm or a 10 ohm resistor in their place to see if it will still work (I'm keeping this amp, so I may as well push the envelope). I'm also waiting on my heat sink order from overseas to come in.

 

[ludoo]

Quote:

Originally Posted by kansei /img/forum/go_quote.gif I'm halfway through building the second one. Currently missing 4 resistors, the 13 and 15 ohm ones. I'm considering putting in a 20 ohm or a 10 ohm resistor in their place to see if it will still work (I'm keeping this amp, so I may as well push the envelope). I'm also waiting on my heat sink order from overseas to come in.

Grab the resistor calculator app, determine the value you need (usually it's 1.25 / 0.33 * 2), set it in the app, you will probably find a couple of resistors you have or can easily find. That's what I did, only I used 300ma for the 7DJ8 instead of the 330 needed for the 6DJ8.

 

[dBel84]

Quote:

Originally Posted by ludoo /img/forum/go_quote.gif I think the Aikido would be my choice.

[size=xx-large]W[/size][size=x-large]H[/size][size=large]A[/size][size=medium]T[/size]![size=small]![/size][size=large]![/size][size=xx-large]![/size] - I have better plans for you me laddie

..dB

 

[MrSlim]

So, excuse me for being lazy, but minus casing, what's the typical cost of building one of these puppies? I see the vendor has the boards for about 7$ right now on ebay, I might spring for one just for prosperity..

 

[ludoo]

Quote:

Originally Posted by MrSlim /img/forum/go_quote.gif So, excuse me for being lazy, but minus casing, what's the typical cost of building one of these puppies? I see the vendor has the boards for about 7$ right now on ebay, I might spring for one just for prosperity..

Depends on where you are, and how far you want to go with boutique components.

The heatsinks are a kind that's a bit hard to find, they are usually available on ebay for cheap but you'll have to add shipping costs. I bought 16 of them (2 sets of 8 instead of 2 heatsinks) so if you have problems with them I could ship you a couple.

The LM317 are ubiquitous and should cost about 50 cents each. The other chips are harder to find, and the only reliable distributor has a minimum order I think of 20$. But then you could get a few and sell them to other people (or trade for heatsinks

).

The resistors are cheap of course, so no big problem there. The pot might be cheap as the PCB has holes foe one of the small Alps with a built in power switch (I splurged on a Blue Velvet which cost about 12 euros), and the connectors won't be a problem either.

What you are left with are caps, ps, case and the tube. Caps might go from a few dollars to a few tens of dollars, depending on what you get. I used Obbligato film caps because I had a pair lying around but if I had wanted to stay cheap I could have used some Vishay caps which cost <1$ each, then bought some Silmic II which cost 12 euros all together.

I have a few NOS 7DJ8 so I did not spend anything on the tube, but if you have a local dealer you should be able to get a decent one under 10$. The PS cost about 10 euros off ebay.

All together, I think you could spend from 60-70$ up. In the EU, from 70 euros up due to higher prices and shipping costs. In my opinion it's totally worth it, it sounds very good (I prefer it to my boutique SS) and it's a really easy build.

 

[ludoo]

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif [size=xx-large]W[/size][size=x-large]H[/size][size=large]A[/size][size=medium]T[/size]![size=small]![/size][size=large]![/size][size=xx-large]![/size] - I have better plans for you me laddie ..dB

Oh lol, like what?

 

[Nemo de Monet]

Quote:

Originally Posted by MrSlim /img/forum/go_quote.gif So, excuse me for being lazy, but minus casing, what's the typical cost of building one of these puppies? I see the vendor has the boards for about 7$ right now on ebay, I might spring for one just for prosperity..

I think you meant "for posterity", but anyway...

Like Ludoo said, it all depends on how boutique you go. 2SK117s are pretty cheap and plentiful, and it should be possible to sub a $1 IRF610 for the 2SK310s without difficulty. You'll probably need to spend $15-25 on a power supply, as well.

Assuming you have no parts on hand, and get as much as possible from the same vendors, to cut down on shipping:

PCB - $14, shipped.
Tube - $15, shipped, or less.
Socket, connectors, heatsinks - maybe $15, shipped.
Transistors: 2Sk117s 3 for $3 shipped, on eBay; maybe $5 for everything else, so $8 total.
Resistors: Maybe $10, if you use nice Dale parts and buy extras.
Caps: Call it $15, shipped, for reasonably boutique parts.
Pot: $12-20, depending on what you pick.
Power supply: Call it $20, shipped.

$100 USD should get you a very awesome sounding amp, less case. If you hunt around long enough, you can probably shave that down to $75 or so, and if you allow yourself $125, you should be able to use fairly boutique parts throughout. To be fair, the majority of the cost goes towards the most important parts - half the cost, more or less, is the power supply, volume control, and tube.

Not as cheap as a Starving Student, but all of us who've built 'em seem to agree they're money well spent.

 

[MrSlim]

I don't know why I'm even thinking about this, since my CTH is sounding pretty nice.. but the fact that the Super Simple happens to use the same type of tube would mean I could share some of the same tubes as people have been playing with the CTH(using a Amperex 6dj8 in it at the mo..) and the board is cheap..

Oh.. and thanks for correcting my Spelling Nemo..

The Starving Student cost has gone up a lot with the demand on the tubes and the power supplies.. and the fact that the 19j6 is becoming more rare is only going to make it more expensive/unavailable..

 

[kansei]

Mine cost in the neighborhood of $80 to build, but I got the power supply for free (HP Deskjet power supply). It's easier to build than a Starving Student because it has a PC board.

I have an extra set of the hard-to-get transistors (2sk310 and 2sk117), let me know if you're interested. I had to buy 10 of each to meet the minimum order. I also ordered a ton of heatsinks if you need those (these have not arrived yet, but soon...)

Take a look at one of my earlier posts which has a BOM attached to it. The BOM is not perfect, but it will set you in the right direction.

 

[DKJones96]

I finally got around to almost finishing this thing(casework that is), and I know a lot of us used the same case so I thought I'd let you all know what I did. I'll get pics up when I get it apart again to finish the case work but we have all been talking about the power fets getting hot with the regular heat sinks, and boy do they ever.

I decided to go a different route than an acrylic case cover since it was so annoying with the PPA and decided to mount the 310s to the case itself using the insulators I bought for my starving student I haven't started yet. I've ran it for an hour and the amp itself is barely warm to the touch, the 310s are cool, the 317s are just as cool with the enclosure sealed up. I highly recommend doing this. All I did was solder patch wires between the fets and the board. However, I surface mounted my tube on the case and mounted the little sinks to the top(gave me something to screw into without an ugly nut) so that may effect how much benefit you get from this, but there is MUCH more surface area and mass on the case than those sinks offer. The tube is now the hottest running component, by far.

 

[AnA1995]

By looking at the schematic, notice that the capacitor C103 of 1000uF is rated only 25v. Is it enough for the input voltage of 24v? Just one volt more is not very safe I think. They should use capacitor of at least rated 35v. Please advise and appreciated. Thanks.