luvdunhill

sure, why not discuss it Any proposition on what needs to change and a mechanism to do so?

bump I've found a PTFE trimmer that seems to be a simple 5mm pitch. So, I'd like to add this form factor to the feedback cap, along with the above stuff, if at all possible.

Jacob: Do you have any idea what the impedance range on the hybrid with 2 switches closed (at most) would be, if we scaled the input impedance to start at 10K? I think this would be a worthwhile calculation.

so, here's my opinion on the matter. If we're considering 10K:10K input transformer, a 10K rotary-style attenuator, such as the PCB mount DACT units would be something to consider as an option for this project. Second, would be the equivalent using relays. This is what I did for my preamp. Yes, lots of relays, I think I have around 70 DPDT relays. Also, with a firmware update, you could accommodate a logarithmic ladder version. This would be a poor choice with the input transformer, but a nice option if you're doing balanced only. Finally, with yet another firmware update (or better yet, toggling an option in the uC) a hybrid with 2 switches closed (at most) could be used, which might prove a possibility with the transformer. Note, all of these versions can be built to any value, 10K, 50K, 100K, etc. by choosing the resistor values appropriately. Obviously, depending on the maximum number of relays allowed for, there would be different step size depending on the version selected. I think think would be okay. In fact, a daughter board could be supported that would add more relays. This approach would be extremely flexible, and in my opinion this would superior option to the TPA JT attenuator. For example, this setup could easily accommodate a transformer volume control (TVA) or autoformer as well as resistive attenuation. Thoughts?

no, he can kit for the output voltages we need, and VA isn't really other than whether or not he includes the on board heat sinks, or we would use off board heat sinking or the 2.5" tall versions of that heat sink footprint.

I highly recommend the "Designing and Building Hi-Fi Furniture" book

heh ... keep telling yourself that.

I have a feeling it will be cheaper for us to ship to them, if you know what I mean.

Guys, I need to get a firm number by tomorrow for the number of populated boards, and the total number of TO-92 heat sinks I need to have manufactured. Please confirm with Icarium ASAP. If you're interested in extras of the heat sinks above and beyond the group buy, it looks like the price will be $2.50 each. Yes, a little steep, but after playing around with these, I'm confident that they offer greater or equal performance to the dual devices, and I'm not really looking backwards at this point. KG: I think the group would be more than willing to send you some of these as a thank you for the Dynafet design, since you expressed interest. Please PM me your address and we can go from there. Here's a picture:

..or maybe start with an Oolong, Pouchong or Puerh

explain yourself. Are you talking about Voltron or the FET-A?

Do you guys warm up your pot / cups with water, prior to infusion?

oops, I was reading too much into your post your right

too bad the UK plugs put out puny current

... and re-wire the Stax units for 2kV bias voltage

ya, the Magico Mini drivers... I forgot about those...

Have you tried any of the aluminum cone SS or the titanium former SS drivers? I cannot imagine they are worth the money... I'm just telling myself that... and the fact that I've taking up an expensive habit with Audio Technology drivers. I really liked the XT25 (I have a single driver for sale cheap if you need something to blow up in a test jig).. it's probably my reference tweeter in that price range. But, I'd definitely suggest trying the Peerless HDS. I just cannot see spending the insane amount of money for things like the SS aircirc or Morel supreme, etc. after playing with the HDS. The only other tweeters that tempted my pocketbook were some of the Hiquphons...

I think I might be able to take Dan... too bad I don't have a transcript of our phone conversation we'd need to level the playground with identical keyboards though. They probably have some super-secret keyboard technology at Google that would give him the advantage.

if that's the case, here's a good quote from their marketing department: diyAudio Forums - F4 power amplifier - Page 24 one other point is Richard's own claim about noise with increasing VA. Nate, how large dounts have you used from SumR? I've used 1000VA units from Plitron that were dead quiet. I think the concern is with increasing current capacity. I just think we should consider a prototype or two before going all in.

Jacob et al. One thing to think with regard to the attenuator will be the input transformer. The input transformer has needs to help inform the circuit, or it will turn out to be a problem. That being said, I don't think a Joshua Tree type attenuator is a good choice, due to varying impedance. The choice of RC loading the secondary, plus the impedance of the volume control mechanism after the transformer will have to be chosen carefully. These interact with the input capacitance of the amp, as well as any input filter or feedback capacitance. My experience with input transformers is mostly with the Jensens. Does anyone else have an opinion on this?

14 pairs, so 28 transformers? The price breaks are: 1-11 = 0% 12-24 = 10% 25+ = 15% 50+ = 20% 100+ = 25% (Maximum discount)

So, latest cost on these is right around $150 a pair. If we get up to 12.5 pairs, it goes down by a whopping 5%. I'm in for 2 pair.

It's a slight mechanical hum, not EMI. Doesn't effect sound really that I can tell.

That Grado reminds me of the tone arm reminds me of the Gray viscous damped arms:

with regards to Pars post in the business thread, I'd definitely go with the larger transformer and go with the same transformer for all builds. I'd recommend 160VA 2x30 VAC with universal primaries. Again, reference Plitron 057017201. With regard to SumR, they are a bit of an unknown. The ones I have seem to have a bit of mechanical noise, but perform okay. Plitron is pretty much the industry standard in audio. I just wanted to throw this out to the crowd, and maybe those who have an opinion on this matter can give their $0.02. This is pretty much a no-compromise type of build and from what I've seen so far, this is the only already I'd consider a slight compromise, just because of the unknown-factor. ... gotta run for a bit, I'll comment more on the other thread later..