Live! Nude! Amp!
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erix

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It's been said the enclosure is the hardest part of DIY so I built an amp without one.



I built this as a plug-n-play apparatus for experimenting with resistor values and input caps. Yes, yes, I know you've heard me bitch about input caps ad infinitum but I figured it's easy to play with different kinds in this form.

The board is 3/4" plywood, the little brackets came on my new window A/C units, the pot is a cheap 50K Alpha (with remarkably good tracking - must've slipped past the QC dept.) with an old Davies plastic knob. Switchcraft jacks round it out.

The layout is based on a layout for the META42 amp by sijosae, who I've admired for his ultra-tidy builds and super-tight layout.



I added the power supply section to his layout along with a switch and LED. The big caps are Cerafine 2200uF/16V bypassed with 1uF/63V Wima MKS2 and the C1 caps are insanely huge 1uF/400V Wima MKP10's.

For this iteration I chose resistor values from ppl's first portable pocket amp. Interestingly enough, most of the values are available in the Shack's $5 1% resistor assortment. I didn't use all the bells and whistles of his circuit (namely the capacitance multiplier, the cascode current source, and the bass boost) - just the multi-loop dual opamp (AD823 in this case) buffered by a pair of EL2001's.

And how does it sound? Abso-freaking-lutely-marvelous! I couldn't believe the power and depth of the bass - this thing can blur your vision. I don't know what it would do with ppl's bass boost circuit. The top-end is nice and clean too, the mids maybe a trifle scooped but in a good, rock-n-roll way.

ok,
erix
 
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zbuddah

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heh naked beaut. hows the bass though you said " I couldn't believe the power and depth of the bass" does that include detailed bass? not muffled right?

I'm still working on mine, trying to look out which caps would work nicely in C1/C2/C3.
 
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puppyslugg

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What a fine looking lady! She have a sister?
 
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andrzejpw

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lol!


So, erix, and comparisons to other amps?
 
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erix

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Quote:

Originally posted by andrzejpw
So, erix, and comparisons to other amps?


Well, I've built:

Three Cmoy/Hansen boards, a Cmoy from scratch, a pair of 47's, and a single-loop buffered amp with AD744's and (2) BUF634's per channel. Each of these amps are good at what they're supposed to do. The Cmoy's are small and battery friendly, the 47 are robust, the buffered amp is incredibly smooth.

These are the only amps I've spent *alot* of time with and though I got to listen to a slew of amps at the WOH tour stop in Mnpls - that was a few weeks ago.

Compared to my other DIY amps, this amp is a whole different animal. The soundstage is wider the highs more transparent, the bass is tight and has so much impact makes you blink.. It's amazing.

Comparisons to amps from the WOH show may elicit some snickers, but here goes. I like this amp better than:
Grado RA-1
Both Creeks
Both Cordas
Headroom's AH, TAH, Little, and Home

The amp I spent the most quality time with at the show was the Max and the thing I liked about it was the bass. This amp has that bass - it's lacking a tiny bit of fullness in the middle that may be because of the lack of processor. But, if you take your Max, set the gain to High and the filter to Brite it sounds really similar, IMHO.

I think this amp will show some improvement with changes in the power section (real PS instead of wall wart), omission of the input caps, addition of the cascode current source, etc.. But it's a fine listen in it's current state.

ok,
erix
 
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Budgie

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Nice job!
 
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puppyslugg

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Quote:

The amp I spent the most quality time with at the show was the Max and the thing I liked about it was the bass. This amp has that bass - it's lacking a tiny bit of fullness in the middle that may be because of the lack of processor.


Could it be Max's ps?
 
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kelly

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What PSU is that?

And have you actually AB compared this amp to the Max?

(The Max has the best bass in a solid state amp that I have heard by a wide margin--if you think you've matched it somehow, I need to know the details--especially if you did so without dual circuitry).
 
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puppyslugg

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Hi kelly,

I thought this thread would get your attention.
 
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post-158771
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eric343

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Nice Job erix! (so you DID have some MKP10s stockpiled away, when you said you were all out
) I really like that layout - it's very elegant. But you've gotta trim and twist the wires!
 
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Gariver

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Hi Erix:

I really think you hit the jackpot with this one! With those comparisons you've made, I've got to say that the META is the best DIY amp to build! Congratulations on a job well done!

The red Wimas look like huge red buildings to me! Yes, it looks like the model of a miniature city block! Ha!
 
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erix

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Quote:

Originally posted by eric343
(so you DID have some MKP10s stockpiled away, when you said you were all out
)


Heh, well when you asked I didn't have any!
I got these in trade and they arrived after you asked. They are HUGE - there is no way they'd fit on tangent's board. I have some Solens and Auricaps that I'm going to sub in this week to see if I can tell the difference.

Quote:

And have you actually AB compared this amp to the Max?


Nope, goin by recollection. The Max at the show had the deepest bass (except for the Blockhead which is a completely different animal) of all the amps present. This amp has the qualities in the bass that I admired in the Max - I'm sure side-by-side it would be easy to pick out the differences, but now, three weeks after the show, I have to say it sounded close. How close is up to somebody who has one of each amp to say (*cough*, JMT, *cough*)


ok,
erix
 
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kelly

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erix
Which PSU are you using?
 
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erix

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Quote:

erix
Which PSU are you using?


Just the big 3-12V "regulated" wall wart from radio shack. At this light load it's probably spittin out close to 15V tho.

From the wart it goes to the TLE2426 which splits it exactly in half then the virtual ground buffer (another EL2001 - just as on tangent's board). Then there's the Cerafines and B.A.W.'s (big ass Wimas...).

ok,
erix
 
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