If you are look for a friendly forum place to find and talk about TDs, go here:
http://www.turbo-mopar.com/
Here is my site (over 10 years old now) of technical stuff for these cars:
http://minimopar.knizefamily.net/
Russ
tubelab.com said:
Yeah, things have come a long way. Between the 5 Turbo Dodges my family owned plus the two I have now, I think we have 17 head gaskets hanging on the "peg of shame" in the garage. We tried all kind of tricks to fix the design issue, but eventually Mopar fixed the over-compression issue in the corners and that problem is over. I haven't had to change a blown gasket ever since I switched to the MP ones. No one uses o-rings anymore, partly because MP doesn't sell the gasket for it anymore. Folks running 10s with 27-40(!)psi of boost run cometic gaskets.
You probably had an A525. Those like to explode and there's really not much you can do about it. Even with a girdle...the case is just not strong enough. Just about any trans that came after can be adapted and is pretty bullet-proof in an Omni. Heavier cars stick with one of the Getrag variants for high-torque (A555/A568). That's what I use.
I'm really sorry...I just can't help it...TDs are my other passion. I promise to shut up about it now.
My feeble attempt of bringing this thread back...here are some pictures of Tubelab related items that have been making progress. The Simple SE and the middle Tubelab SE just need sockets and coupling caps. I want to punch the chassis before soldering the sockets. The 3rd SE is going to be for experiments.
Your PCBs are probably the easiest I have ever worked on. The huge solder pads make it really easy for anyone to solder. Setting up the SE for under-chassis mount has a few wrinkles, but it's pretty easy to figure out. The Simple SE couldn't be simpler to build, so if the Simple PP will be anything like that, I'm sure it will be a hit.
Sorry George, between my "Thomas" amp and the VTA-70, I am getting push-pulled-out. Need some SE action. Maybe some day I'll want to build a small EL84 amp, but at the moment I am actually really impressed with how the ST-70 sounds all rebuilt with the VTA driver board. It's like a different animal...totally leaves the Thomas amp in the dust for that room (though the Thomas sounds good in my much smaller office).
I've got a few 45s on-hand now, so I'm looking forward to bringing up the SE board....
Ouch. All of the newly-emptied space around us is being filled with folks from the other buildings. They plan to sell our site and lease back part of it. At least their long-term staffing goals are being made clear by this move.
Sorry to hear about the soon-to-come fire. I don't envy what our hardware team has to deal with either, even though they sometimes drive me crazy.... It's no fun working-away all of your free time.
Russ
Look at post #2 in this thread:
http://www.diyaudio.com/forums/tubelab/167250-sp-p-final-connections.html#post2195794
Sherri has been staying with her mother for the last 5 weeks. The cancer has progressed and "last chance chemo" treatments are being tried now.
I was at work for 72 hours last week. Got home at 8PM tonight. Right now I am "critical path" on a high visibility project (laying out a 10 layer PC board that contains 632 parts in a 2.5 X 5 inch form factor). If I can get caught up I plan to take a few days off to visit Sherri and her mom in early August. My daughter and grandkids are comming too.
Unfortunately tube time = near zero for now.
I have tried several power toroids for OPT's. Some work great, some work OK, and some have poor HF response. Each one is different and it seems that each case must be tested for suitability. I have come to the following generalizations.
All toroids are far more sensitive to DC current imbalance. Toroids that were designed for OPT use are more sensitive than an equivalent sized EI cored OPT, toroids designed for power supplies are more sensitive than toroids designed for OPT use. This fact gives a clear advantage to a circuit with the ability to adjust the bias on each output tube independently to cancel out the DC imbalance.
The probability of success goes down with the size of the toroid. The big ones (over 200 VA) often don't have enough primary inductance for big bass.
Toroids, and cheap OPT's in general will work best when driven by a low impedance source. Triodes work better than pentodes for this reason. Low Rp triodes are best.
Toroids are often scramble wound, so two identical toroids may perform differently for OPT use.
When connecting multiple windings in series, try all different combinations of different connecting order to minimize inter winding capacitance.
For HiFi use it seems that using a toroid that is rated for 4 times the VA than the desired output watts is needed for bass response. IE a 80VA toroid for a 20 watt amp. You can use 2:1 or even 1:1 for a guitar amp.
Forum member Shoog has made several amps using mains toroids for OPT's. Some used 6AS7's which is a good choice due to its low Rp. You can search the forums for his designs.
I also have a SPP type design that uses 50 VA Antek toroids for OPT's, but it is used for a guitar amp.
All toroids are far more sensitive to DC current imbalance. Toroids that were designed for OPT use are more sensitive than an equivalent sized EI cored OPT, toroids designed for power supplies are more sensitive than toroids designed for OPT use. This fact gives a clear advantage to a circuit with the ability to adjust the bias on each output tube independently to cancel out the DC imbalance.
The probability of success goes down with the size of the toroid. The big ones (over 200 VA) often don't have enough primary inductance for big bass.
Toroids, and cheap OPT's in general will work best when driven by a low impedance source. Triodes work better than pentodes for this reason. Low Rp triodes are best.
Toroids are often scramble wound, so two identical toroids may perform differently for OPT use.
When connecting multiple windings in series, try all different combinations of different connecting order to minimize inter winding capacitance.
For HiFi use it seems that using a toroid that is rated for 4 times the VA than the desired output watts is needed for bass response. IE a 80VA toroid for a 20 watt amp. You can use 2:1 or even 1:1 for a guitar amp.
Forum member Shoog has made several amps using mains toroids for OPT's. Some used 6AS7's which is a good choice due to its low Rp. You can search the forums for his designs.
I also have a SPP type design that uses 50 VA Antek toroids for OPT's, but it is used for a guitar amp.
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