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Another question on input sensitivity - I am using a LampizatOr with volume control to drive my power amp directly. Recently I tried a Fleawatt amp but because if it's high sensitivity I couldn't get the Lampi volume control above -50bB before the it got too loud. Unfortunately the Lampi volume control works much better at the high end of it's range, so I couldn't use the Fleawatt in my system. Do you expect that I'll have the same issue with the Folsom 7297?
What are some good sources for wire? What different gauges would you recommend?
BTW if you want to get this buffer, here's the DIYaudio thread about it. Let's just say it's for advanced people, however.
You could move the transformer to the front, face it's connections towards the back. Then put the antipole up against the dividing wall so its ground faces the transformer. The rest of the space... I guess you have enough room to add another transformer and dual rail power supplies, then use buffers too. Big project, but you've got room to fit everything I put in my preamp thing, inside of that chassis! The only minor issue is the buffer has to be turned on before the amp. I suppose that would be a more advanced thing to do.
Jeremy,Is that 2 buffer boards stacked together (blue ones)? You say this is for advanced people, but with a good build guide would it be possible to be dumbed down so the the not so advanced could combine this buffer with our Folsom amps?
Folsom--If going this route, would you have the ground plane of the antipole board directly opposite the dividing wall from the transformer, or would putting the transformer on one end and the antipole with ground plane facing the dividing wall on the other end of the enclosure be best?Best of luck on your build limits
Thanks for the feedback and suggestions Lacro and Folsom and Limits. I thought of putting the amp board in the narrow area (where the transformer is in the photo) but hooking it up to RCA inputs and binding posts (for outputs) would be a real space challenge there.Neil
As far as hum, that's the downside to these transformers that block a lot of RF. I've even put dynamat around them in the enclosure to help. If I could find someone other than Hammond who had some in stock I'd probably go with them instead, as they'd probably make less noise. Might need rubber where the bolt makes contact to the chassis, too, with a washer. That way you've got three of them.
I believe in the build guide I included notes about wire sizes that work for the DIY7297. 20-30ga for signal, 20ga or 18ga solid works for output to binding posts, 18ga works nice for linking the boards together (16ga solid may fit the amp board input), Antipole can take up to 14ga solid at both ends.
Yes 16ga solid will work in place of 18ga stranded. The hum really is annoying, I know. If Mouser had another transformer that could given the same level of performance without it, I'd change the BOM. But right now the only other choice I think I'd make is from somewhere totally different, overseas.
I used 16 ga solid (on one leg) from the Antipole to the amp board without any issue, but I'm not sure about the speaker connections on the amp board. I used 18 gauge stranded, and it fit, so I'm thinking 16 solid might. Hopefully Folsom will know for sure.Also a quick note to constructors: just finished my amp (sound is very promising, and it's just started to break in; had no issues with assembly or instructions), however you MUST use rubber washers between the transformer and the chassis. I tried my amp (testing to make sure everything was correct with voltages etc) before hooking it up in my system, and it had no hum what so ever just plugged into a wall socket and nothing else hooked up to it. As soon as I got it installed in my system, got the dreaded mechanical transformer hum and had to disassemble and install rubber washers as described by several posters.
