[ppl]

Photo one front view inside View

 

[NotoriousBIG_PJ]

Hi PPL, can you share some details about your amp?

Thanks,

Biggie.

 

[ppl]

I was giong to post the full compliment of photo's but thay are larger than 25k and i dont know hopw to reduce the File size.

 

[Voodoochile]

Nice job, ppl. I like the flattened bats on the toggles. Tell us whats going on behind tht bezel now

.

 

[Cheeba-Fi]

ppl,

What type of image editing programs do you have? As much as you have helped everyone, I'm sure that we can help you out with getting your pics on line. The first questions I would ask are, what resolution are the images at? and what file format are they saved in? Anyway, give us some idea of what software you have for images and I'm sure that we will be able to come up with a solution to your problem.

Namastay,
Cheeba-Fi

 

[kerelybonto]

ppl, if you can get them online, you can use the tags to post large pictures.

I have a site I can put them on for you, if you'd like.

kerely

 

[ppl]

Thanks pm with details Maby someone can reduce the file size for me i have MS Paint Picture it Adoby Photoshop and all resizing i tried resulted in bad quality. Each of the other Gifs are 150 - 330 Kb Larger than this fourm allows However i notice others like artness post large and clear pictures.

 

[Serow]

Thanks for sharing your vast amp-building experience with us DIYers, ppl

.

 

[ppl]

Well i hope these illistrations allow users to see the details of one of my amps and in this case my pocket one that inspired Apaheared and the Meta42. this amp as you can tell is a good test bed to compare Chips in. The Top photo is Stock (2) EL-2001's as VGD. AD-8620 as the opamp. Dual transistors used as current sources and Casscode Opamp Bias Transistors. The use of a dual opamp and Dual transistors tacking up as mutch room as a single device allows all the Concepts of my pocket amp to run effecently on a pair of 9 volts. The Second Photo is as you might have gessed a pair of EL-2008's installed in Sockets so as to plug and play just like tubes. Not 9 volt battery frendly 4 Hr Runtime will batteries shown. The next photo down is probaly making folks wonder Why a black Knob on silver, Because i havent a silver one at the time and the black is now growing on me. Last but not least
In my day all IC's and transistors had wires. Pinout differences could easly be delt with but with the Poularity of Dips and Now SMT's pinout is a real issue. This retro like the others is fully funtional as showen The Buffers are an easy gess What opamp do ya think that is remember it is same date as buffers.

 

[ppl]

Attached is the Schematic to the Attached Amp. I know that is realy importent to understand this design sorry for the delay

I am sorry but the previous schematic had errors so a new corect one is attached

 

[Voodoochile]

Wow... can-packaged BB amps! I havent seen them for quite some time. Thanks for the schematic, as well.

 

[ppl]

Those are BB Buffers OPA-633. the Can dual opamp is also BB OPA-2107.

 

[kfaiman]

ppl,
on your schematic, R3 is 10k. I was wondering why you used this value here w/ the AD8620 (I use this opamp w/ EL2009s in my META42). R3 corresponds to R1 on the META42. According to Tangent's site, "The main purpose of R1 is to help balance the op-amp's input impedances. I'm not sure how to calculate a proper value for this resistor; 1 Kohm or less seems to work well, however."

Influenced by your postings and schematics, I am going to experiment w/ the resistor values in my META42 (w/ 100k pot):

R1: 10K
R2: 2M
R3: 953
R4: 4.75K
R5: 10.5K
R6: 2M
R7: 150
R10: 953

What do you think? This gives a gain of about 5.8 (using Tangents calculator). My current setup has a gain of 13, which is WAY to much for my 48ohm ATH-W100s (rarely go past 9 o'clock). Thanks for all your valuable info and advice, ppl.

 

[ppl]

kfaiman. In the attached Schematic R3 and R5 are both 10K so as to balance the Impedance in the Opamps input the rather High Value is to keep the Influence of the 1K to gnd at a min. I talked about this impedance matching on this fourm and in reply to tangent as no one seems to understand the reason for them. Also the 10K makes the Impedance matching better at intermedeate volume control settings not perfect but closer.


joe dick> The AD-8620 is soldered to a machiened pin IC socket. You must first flatten and fan out the Pins to align with the Dip Pins then I used 4% Silver solder and you might have to add small peices of silver wire in the End pins but if faned out properly that is not needed.

 

[JMT]

Joe, that may work, but might I suggest that you simply use an alligator clip to hold it and a straightened out paper clip to maneuver the chip pins squarely on the solder pads.

ppl, great stuff!