luvdunhill

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!

It may be worthwhile to talk with Parts Connexion, as they still service these units and may have some upgrades and mods available if you're interested in putting some more money into this DAC down the line ..

solid state

I think Grawk was getting at the fact that no matter what you do and when you do it, you've already really injured your credibility by making the statement above directly to the vendor which you'd be reviewing.

yes no

oh, so a three-way dispute now. I say you guys have to roshambo...

wait, conflicting info here!! You two must resolve this! I knew Al talked with Pete at length at the Dallas meet about iron, so 909 must reveal his source as well!!

well, I can help there. The PSU are very simple CRC supplies. Which means, you need capacitors and resistors. Minimum you could get by with $50 or so plus whatever Peter is charging for the PSU PCB (for stereo amp). You could easily point-to-point this, but I'm not sure I'd recommend that for a first project. Then you need 2 bridge rectifiers and things like jacks wire and what not. Say, another $50. Finally the transformer itself, so say another $100. Heat sinks and the casing materials might be around this same cost, who knows. Depends if you go with surplus heat sinks and how easily you might be able to fabricate a case.

heh, just razzing you a bit. Anyways, the owner of that place is a nice guy. The boards pictures above can be bought at the links posted in my Spring Cleaning for sale thread. The designer and seller of those boards is the guy who built the amp that is posted above

ya mean other than the link I gave to tech-diy that sells kits? heh anyways, Peter's build is using some premo stuff.. ever what makes a resistor cost $15?

actually, I don't think this is correct. (But correct me if I'm wrong). I think it has more to do with the fact that CD started as 14-bit and as a result had non-linearities at high frequencies and low volumes.

So, just a question for ya'll.. how many CDs do you have with pre-emphasis and what do you feel is the best way to handle playback of these CDs? In my case, they are mostly Japanese recordings. If you rip music off these discs, do you handle this in the software domain? If you're not ripping music, it seems like a lot of newer equipment doesn't handle this spec at all... In the DIY realm, what do you think of handling this in a passive fashion, much like an RIAA circuit, pros/cons?

so, it's not that hard to park the needle on the grid and slide the base without stressing the cartridge suspension?

right, so think of it this way. If there was indeed a resistor from each RCA to ground, they would in effect be paralleled with each other. So, a single resistor in this case is equivalent.

perhaps, assuming that there is no continuity from one RCA earth to the other RCA earth. If there is continuity, then that means the outputs share a ground and that single resistor serves as a ground breaker for both outputs.

Hey Pete: How does the SME setup jig work? Could you perhaps post a picture of it?

ah, ok well, if Spritzer's currency drops through the floor again and starts selling things off, talk to him about a certain pair of heat sinks he has

Duggeh: Would you be at all opposed to transplanting the F5 inside the current Aleph? We could run some numbers on the toroid and the PSU, but it might just work ...

"lamp cord spool"

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.

first hit on google seems to have it for $0.19 a foot.

I agree, looks fantastic! What about Justin's suggestion of the input filter? Here's one that I used, and I've also swapped the location of R34-R35 to be after the caps. I'm partial to polystyrene caps here (e.g. Newark 96K9640), but micas are another possibility. While we're on the subject of caps, I've had very good luck using Teflon (PTFE) caps in feedback loops. Would it be possible to add a second pad to support this? This would not be a standard option, but more for me to tweak with The Voltronics stuff at Mouser is good, but very expensive. Another choice would be Vishay/BC sold at Newark. Both places, just search for "PTFE trimmer". All that really needs to be added is one pad... what that be possible? Finally, what about adding the Wima FKP2 bypasses? I still think this is a good idea wherever possible.

I was referring to the input transformers

so, is there a ground plane on both sides of the board? I know amb does this with his boards a lot... I'll look over it some more tomorrow... edit: also, I would recommend cutting off the ground plane around the output devices, or is that what the dashed line is for? I'm confused I suppose

hey, do you have any rough costs for case cost? any estimates from your beta22 builds would probably be right on, plus the differential cost in the cases. Also, the transformers come in a PCB version.. it would be cool if those got integrated into the I/O boards. If you can get OEM cost, I could probably get some other people interested as well to help the numbers.