I think I found an answer.... There is an issue when using any of these Balanced Line Drivers against an Unbalanced Load, noise. Read Wayne's response on this TI Thread: THAT1646/DRV134/SSM2142 Driving Unbalanced Loads
On Page 14 of the TI Datasheet for DRV134, you can see they recommend tying off sense and unused drive phase to ground:
DRV134 Data Sheet
Bit of an update:
After finding that I had reversed Q7 and Q8 on the right channel, and installed them backwards; after finding that I had confuzzed 7815 with 7915 as well; and after changing out R27 for a 680R as per Boydk's suggestion, I'm now getting much better rail voltages of 20.1 V on each side.
However, I'm getting a whopping 14.5 volts at R27, and with the 680R in there, that's 21.9 mA. seems like I'm about 4 times over spec. So I think I need a 27.2k resistor for R27. Should I still be looking for other mess-ups? And darnit, one of the blue LEDs just went out.
After finding that I had reversed Q7 and Q8 on the right channel, and installed them backwards; after finding that I had confuzzed 7815 with 7915 as well; and after changing out R27 for a 680R as per Boydk's suggestion, I'm now getting much better rail voltages of 20.1 V on each side.
However, I'm getting a whopping 14.5 volts at R27, and with the 680R in there, that's 21.9 mA. seems like I'm about 4 times over spec. So I think I need a 27.2k resistor for R27. Should I still be looking for other mess-ups? And darnit, one of the blue LEDs just went out.
7815/7915 are making +/-15volts - everything else is bad.
I only can repeat my offer: make many-many pictures from different angles in good resolution, so we can check your boards.
Anything else would just be guesswork.
I'm going to try to get the pics you ask for, but as I have posted several times, I am nearly blind now, and it is not so simple to do. Even pulling the boards from the chassis is much more time-consuming than it should be.
I do appreciate your offer very much. I just want you to know that my slow response is not because I don't want to accommodate your ask, but that I have to go very slowly.
Nothing wrong with slow response 😀
More eyes see more 👍that's why I'm asking for pics, we simply don't know your boards and therefore your mistakes.
More eyes see more 👍that's why I'm asking for pics, we simply don't know your boards and therefore your mistakes.
In the meantime, some progress with my Pearl 😀
Yes, PSUs in the middle, but - because I'm crazy - there will be two Toroidy supreme audio donuts...
Aluminum sides and dividers, iron top and bottom, aluminum front and rear plate.
I may cover the dividers and sides with iron plate too.
Aluminum sides and dividers, iron top and bottom, aluminum front and rear plate.
I may cover the dividers and sides with iron plate too.
If you can, put the iron between PSU and RIAA, to contain the magnetics away from the RIAA.
@Plott
two power supply transformers isn't in the least crazy. on the other hand, bundling them with the signal boards when conventional wisdom is to keep them separate by a metre or two or more...
are these "supreme audio donuts" different from normal toroids? I've seen round section toroids that were supposed to perform better but I seem to recall they were from a different manufacturer.
Also, Antek has a shield design with an extra wire to ground that might be used to advantage, no?
just wondering...
two power supply transformers isn't in the least crazy. on the other hand, bundling them with the signal boards when conventional wisdom is to keep them separate by a metre or two or more...
are these "supreme audio donuts" different from normal toroids? I've seen round section toroids that were supposed to perform better but I seem to recall they were from a different manufacturer.
Also, Antek has a shield design with an extra wire to ground that might be used to advantage, no?
just wondering...
@Plott
I was thinking of the R-core transformers made by James Transformers
http://jamestransformer.com/en/transformer/R_core_transformer.html
I was thinking of the R-core transformers made by James Transformers
http://jamestransformer.com/en/transformer/R_core_transformer.html
My Pearl had no chassis until now, the stock donuts were 10 cm away from the amp board - absolutely no hum or whatever.
Regarding the new donuts, that's what the company says: "Supreme audio grade transformer is dedicated for use in power amplifiers and other high-end audio devices. In Supreme audio grade, noiseless transformer You'll get transformer wound on highest inductive, laboratory selected and tested core. For a best noise reducion core and all the windings are impregnated . Transformer will also has electric and electromagnetic shields. Whole transformer is vacuum encapsuled, epoxy filled in a polished, stainless steel box."
These donuts are used in some well known high end audio products.
Further, I'm in Europe and the transport prices from the US are extremely high, often above the price of the goods. Plus custom duties plus VAT...
Regarding the new donuts, that's what the company says: "Supreme audio grade transformer is dedicated for use in power amplifiers and other high-end audio devices. In Supreme audio grade, noiseless transformer You'll get transformer wound on highest inductive, laboratory selected and tested core. For a best noise reducion core and all the windings are impregnated . Transformer will also has electric and electromagnetic shields. Whole transformer is vacuum encapsuled, epoxy filled in a polished, stainless steel box."
These donuts are used in some well known high end audio products.
Further, I'm in Europe and the transport prices from the US are extremely high, often above the price of the goods. Plus custom duties plus VAT...
Last edited:
The Toroidy are probably the best transformers available, anywhere. 😎
got a link for that? please.
James also has an "O-core" version. It's not clear to me where this company is located. the transformers are made in the east as far as I can tell
James also has an "O-core" version. It's not clear to me where this company is located. the transformers are made in the east as far as I can tell
https://sklep.toroidy.pl/en_US/c/Toroidal-transformers-SUPREME-AUDIO-GRADE-V2/99
Even Toroydi make custom transformers, if you ask them. For a dual mono Pearl you can have one transformer
with 4 separate secondaries. Will also save you some money.
Even Toroydi make custom transformers, if you ask them. For a dual mono Pearl you can have one transformer
with 4 separate secondaries. Will also save you some money.
Last edited:
Yes, all my NP and ZM amp have Toroidy donuts, all custom made, in the audio version.
Now is the first time I ordered the supreme audio grade V2.
They are very flexible and Hubert is very helpful.
Now is the first time I ordered the supreme audio grade V2.
They are very flexible and Hubert is very helpful.