I was thinking another 6V6/6P1P... But, I do use this MOSFET as a source follower in my only SS amp - https://ixapps.ixys.com/datasheet/ds100177b(ixta-tp-th6n50d2).pdf
It's a very good sounding MOSFET if it's a little overkill for a preamp...
If you use a MOSFET, ensure it's depletion mode! Then you can say it's almost a tube based on it's normally ON characteristics.
It's a very good sounding MOSFET if it's a little overkill for a preamp...
If you use a MOSFET, ensure it's depletion mode! Then you can say it's almost a tube based on it's normally ON characteristics.
The drive is basically a function of the coupling cap and plate resistance combo. Get low enough plate resistance, and a large enough coupling cap and you're good.
If using a high plate Z tube, a mu-follower CCS can be employed. Riding a 6AH4 triode at 20 mA, we got 31R output Z at 1 kHz using a 5 uF, metalized polypropylene motor run coupling cap.
cheers,
Douglas
If using a high plate Z tube, a mu-follower CCS can be employed. Riding a 6AH4 triode at 20 mA, we got 31R output Z at 1 kHz using a 5 uF, metalized polypropylene motor run coupling cap.
cheers,
Douglas
as headphone amp
Someone a few pages back asked about using this amp as a headphone amp. I did it running the gain stage into the CF stage, and just thought I'd post my results. It's similar to the bottlehead crack, so here they are side by side. My measurements going into a pair of Beyerdynamic DT 990, 600 Ohm cans, and another measurement of the crack from a review site, also into a 600 ohm load. My subjective experience also matches those from the crack reviewer.
This 6v6 version a bit lower noise than the crack due to using a Maida and DC heaters, and also H4 a bit lower too, but otherwise similar animals.
If you run the preamp into a regular line stage (20kOhm load and above) as intended, H3 and above all disappear to to -110db, pretty amazing.
Someone a few pages back asked about using this amp as a headphone amp. I did it running the gain stage into the CF stage, and just thought I'd post my results. It's similar to the bottlehead crack, so here they are side by side. My measurements going into a pair of Beyerdynamic DT 990, 600 Ohm cans, and another measurement of the crack from a review site, also into a 600 ohm load. My subjective experience also matches those from the crack reviewer.
This 6v6 version a bit lower noise than the crack due to using a Maida and DC heaters, and also H4 a bit lower too, but otherwise similar animals.
If you run the preamp into a regular line stage (20kOhm load and above) as intended, H3 and above all disappear to to -110db, pretty amazing.
Attachments
Last edited:
Looking at some listings on Mouser to finally order parts to populate these boards, and it looks like the SPR/KOA are out of production? Well, either way, looks like I'm going with the AC line by Vishay-
AC05000001002JAC00 Vishay / Draloric | Mouser
Decent priced, durable, available in a decent selection of sizes and should work well. I really like Vishay parts in general from past experience. I'll go for Vishay CMF or generic stuff on hand for all the non-power resistors.
AC05000001002JAC00 Vishay / Draloric | Mouser
Decent priced, durable, available in a decent selection of sizes and should work well. I really like Vishay parts in general from past experience. I'll go for Vishay CMF or generic stuff on hand for all the non-power resistors.
Last edited:
mooreamps, this has already been decided.Some discussion not on the thread topic has been removed. Some posts were rules breaking and are being considered by the team.
Further (civilised) continuation of this topic should be taken to its own thread.
Parts came in today! Sneak peek at the populated boards- going 6AQ5 for the octal/seven board, and 6p43p-e on the noval board. The wima output caps I ordered are huge compared to what I usually use, it's been a while since I used such a large film cap! Thankfully everything I ordered fit the boards perfectly.
In the next few days or so I hope to have a power supply together so I can test them, and go from there. I think that will be a new thread, with better pictures and more discussion.
In the next few days or so I hope to have a power supply together so I can test them, and go from there. I think that will be a new thread, with better pictures and more discussion.
Attachments
Soon
I will do an initial build and test of them, then send a few out to others for testing. We will make any necessary changes to the board, and then do a larger order to sell them to members. Logistics still to be decided there.
