As my first tube project, and since I needed a desktop computer amplifier, I built these mono block amplifiers.
It is a simple 6SN7 common cathode input with a dc coupled cathode follower, with an EL84 power tube stage in SE UL (60% tap) output stage.
The OPT is a double c core 5000:8 Ohm design.
The PSU is an smps off-board box, with B+ at 262V @ 140mA dc and filaments 6.3V @ 5A.
Power out is a nominal 2.2W per channel. LTSpice simulation shows approximately 6% H2 at this output level. This matches measurements reasonably well.
I am enjoying listening to this configuration which probably "presents" the EL84 "sound" reasonably well.
It is a simple 6SN7 common cathode input with a dc coupled cathode follower, with an EL84 power tube stage in SE UL (60% tap) output stage.
The OPT is a double c core 5000:8 Ohm design.
The PSU is an smps off-board box, with B+ at 262V @ 140mA dc and filaments 6.3V @ 5A.
Power out is a nominal 2.2W per channel. LTSpice simulation shows approximately 6% H2 at this output level. This matches measurements reasonably well.
I am enjoying listening to this configuration which probably "presents" the EL84 "sound" reasonably well.
Attachments
A bit of both... I used evaluation boards from TI for the 6.3V and LT for the B+
Both modified for the correct voltage, and the LT 3751 controller was changed to a regulated (as opposed to a capacitor charger) supply.
Both are fed from an unregulated 33V dc supply.
TI:- TPS5450EVM - a nice little board costs 10USD gives 6.3 5A and can take an input as low as 8V;
LT:- LT3751 dc/dc flyback converter modified to regulate at 262V a compact board that can be modified relatively easily for slightly higher voltages and currents cost 110USD
Attachments
Digikey.com
The LT3751 board is Demo Circuit 1322. It comes as a capacitor charger and you will need to change the feedback components to suitable values and possible other components such as the mosfet current limit resistor (R16 in the user guide) if you want higher output current. I think the supplied flyback transformer is good to about 8A in the primary but it might be best to check with Linear. Also change the supplied output capacitor C5 as it gets hot under regulator mode (you only need about 10uF at this point, and a few 100uF at the OPT tube stage)
The filament supply is TPS5450EVM, you only need to change the feedback components
you are using klipsch i see
what model, and are they really that sensitive? good for se?
Sound quality?
Would a klipsch floostanders fill the room with 8w se? What do you think
Klipsch R14M. I think it sounds great with the SE but I am not an expert!!
Claim is 90dB but I have not measured them!I am not familiar with the floor standers sorry
but 8W is a fair bunch in a decent room
Is there a good source for info on how to calculate parts values and implementation? Thanks.
Yes, there is a good user's guide on the digikey site, (search for TPS5450EVM)
Look at the circuit diagram on page 13, I changed R3 from 0 Ohm to 3k3 which gives a calculated voltage of 6.36V (VSNS is regulated to the 1.221V reference)
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.