February 12, 200917 yr As far as what case we are going to use I think we need to wait till boards are finalized so we know their size and also know everything else we plan to fit in the case. As for I/O what do people want? I was thinking for the back: SE/balanced inputs, maybe a loop out for each, SE/balanced preamp outs. Speaker if you think it's up to the task. Now do we want to use something like the e24 for switching power on/off with a nice lighted switch on the front? Matching switches for switching inputs and outputs? Single 4 pin XLR on the front or dual 3s? Or both. Two SE jacks or one? As for the connectors I was thinking Neutrik for the XLRs and Cardas (OEM price) for the RCA and speaker (if we have it). Or if you guys are feeling froggy WBT but they have a minimum order to get the good OEM pricing. Also what about volume pot? Dact? TP Joshua tree if they are available? If TP had the JT and Femto available we could make it with a nice display and have remote control. There's always Dantimax... Dantimax (elektronik) - Kits I should stay out of these discussions as I plan on my SE set to interchange with a Dynahi under construction, I already have case, pot, etc. and plan a very simple rear panel as this will only be a headamp. Edited February 12, 200917 yr by Pars
February 13, 200917 yr By the way i would like 4 boards minimum 8 boards maximum. I'll build them myself... Kevin if you need any help with the build don't hesitate to ask.
February 13, 200917 yr Kevin if you need any help with the build don't hesitate to ask. Actually i do need help. I'm trying to find a single piece of burl walnut. I would like it to be a single crack free cube of size 10 x 8 x 6 inches or a piece of aged lignum vitae, same size. Fine: I want 8 circuit boards. I will assemble them myself.
February 13, 200917 yr ^ I'll look around. That may be hard to come by, but I have a feeling I know your plan, and it would be sweet as all hell. PMed! Edited February 13, 200917 yr by swt61
February 13, 200917 yr Kevin if you need any help with the build don't hesitate to ask. Steve does the soldering, Kevin does the chassis woodwork.
February 13, 200917 yr Also what about volume pot? Dact? TP Joshua tree if they are available? If TP had the JT and Femto available we could make it with a nice display and have remote control. I already have case, pot, etc. and plan a very simple rear panel as this will only be a headamp. Its look like that everybody want to do/have something differently and some already have case, pot, jacks etc and do not need anything. I would suggest making a list of main custom things and letting everybody tell what they want/need or how they see it. Thus we can understand which and how many custom things we need in the future. [*]Case
February 13, 200917 yr Good call. That maybe should go into a separate thread that only has posts for that. Btw vvs_75 I still think you do nice looking work
February 13, 200917 yr Good call. That maybe should go into a separate thread that only has posts for that. Btw vvs_75 I still think you do nice looking work Thanks . Just want to be useful.
February 13, 200917 yr Another thing that I am definitely going to use in mine is an e12 board... actually the modified one I did up awhile ago and use in my Dynalo. This one uses a 555 timer, but more importantly has a manual mute switch; nice for changing headphones without worriesLED drivers/outputs for normal and mute/fault statesoption to tie fault test ground (pin 2 of the opamp) to the amp ground Most of you seem to be planning on doing balanced DynaFETs; the ability to deal with 4 channels (or more?) must be addressed if any are interested in this. Since this is Amb's design, even though more or less open source, it should be run past him to see if he objects. I suppose pairs of standard e12s would work for the most part also.
February 13, 200917 yr One other thing to consider is that if anyone is planning to go the speaker output route I'd recommend putting a Zobel on the outputs. I've actually worked up a little Zobel PCB that I'll be ordering a few of if is interested.
February 13, 200917 yr Author One other thing to consider is that if anyone is planning to go the speaker output route I'd recommend putting a Zobel on the outputs. I've actually worked up a little Zobel PCB that I'll be ordering a few of if is interested. A Zobel network shouldn't be necessary with the Dynafet due to the feedback design. If you want this sort of protection, and output choke might be a better choice. For example, say you're using a Piezo tweeter in your speaker design. In this case, the load doesn't tend to be inductive at high frequencies, but capacitive. In this case, the Zobel network is a poor choice and the output choke would better protect your speakers. The problem is that the values in the Zobel need to be chosen carefully with respect to the design for optimum performance. With this said, the only person at this point who can really comment on this is Kevin, so I'll freely admit this is just speculation on my part.
February 13, 200917 yr Well, here's what I really want. No it's not overkill. Let's then do it for everybody!
February 13, 200917 yr Well, here's what I really want. Looks good to me. With the exception of current monitoring all that could be done with Femto/AC1/JT/e24.
February 13, 200917 yr use the in-line non contact hall effect current devices for monitoring the current. Same ones i used in the uberamp. Allegro | Hall-Effect Sensors | Current Sensors
February 14, 200917 yr use the in-line non contact hall effect current devices for monitoring the current. Same ones i used in the uberamp. Allegro | Hall-Effect Sensors | Current Sensors I was looking at those, but even the lowest-ranging ones seem to have a significant amount of noise - equivalent to 80mA RMS or so on the rail even with a moderate amount of filter capacitance (from page 9 of the ACS713 datasheet). Are they actually "good enough" in practice? If so, I'll add a pair of those, an i2c ADC, and some temperature sensors right on the PCBs.
February 14, 200917 yr Actually i do need help. I'm trying to find a single piece of burl walnut. I would like it to be a single crack free cube of size 10 x 8 x 6 inches or a piece of aged lignum vitae, same size. Fine: I want 8 circuit boards. I will assemble them myself. Specializing in exotic hardwoods of the World They also have an Ebay store... http://cgi.ebay.com/XXF-HUGE-WALNUT-FIGURED-LUMBER-2521L-EXOTIC-WOOD_W0QQitemZ360129433130QQihZ023QQcategoryZ84011QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262 They will be able to help - though Honduras Rosewood would be cooler, or Cocobola.
February 14, 200917 yr I was looking at those, but even the lowest-ranging ones seem to have a significant amount of noise - equivalent to 80mA RMS or so on the rail even with a moderate amount of filter capacitance (from page 9 of the ACS713 datasheet). Are they actually "good enough" in practice? Well for the uberamp which idles at 1.5 ampere, they were great. They are a little noisy down in the dumps. But really each rail should run at 200 to 300ma, so it may be ok. They did at one time make lower current devices.
February 17, 200917 yr Author still waiting on one last quote for the Renesas Technology parts... geez they're slow. I've talked with Sowter as well, since I need a pair of input transformers for another project and got the following quote. The model is very similar to the unit on Voltron's Doshi preamp (see Sooper Secret Internals thread), but has upgraded features. The model isn't available on their website directly (at the moment I think it's OEM only), but is similar to the 3575. It is PCB mount with UPOCC wire upgrade. Since I'm pretty sure not everyone is interested in this, I got a quote for 6 pairs and including shipping from GB and shipping from me to you, I'm estimating $130 a pair. The next step up would require 12.5 pairs and would only net a 5% discount, which doesn't really seem worth the effort to me. Soon I need to collect money for the small heat sinks and a deposit for some of the semiconductors to get the ball rolling. I think $120 for stereo build and $240 for a balanced build is a good start. If there are left over funds, they will go to the prototyping of the boards and free heat sinks to Kevin. I took these prices from Pars BOM. In actuality, I will probably be purchasing the 2SA1145 and 2SC2705 in bulk (sealed Toshiba packaging as they are still current part numbers) so if you have any desire for extra parts there will be a lot available. Also, if you want extra EDM heat sinks, please let me know as I can order them. Also, I'd recommend the builders to take a look at the schematic and note areas which it is important to match transistors and resistors. Thanks everyone!
February 17, 200917 yr So if we are a worthless non builder would the idea be throwing in an extra 50 percent in the semi conductor warchest? Would it be worth attempting to match builder to buildee at this point for boards at any rate?
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