Yes,
I would seriously suggest you use a larger chassis.
Otherwise I did 2 things to make it fit in tyhe small chassis.
1) The various CCS's and front end components were mounted on some "Vero board".
2) The Mosfet Source follower CCS loads were made as little sculptures as per post #571 and hung in midair.
Building into that small a chassis was very difficult and required lots of planning.
Cheers,
Ian
I would seriously suggest you use a larger chassis.
Otherwise I did 2 things to make it fit in tyhe small chassis.
1) The various CCS's and front end components were mounted on some "Vero board".
2) The Mosfet Source follower CCS loads were made as little sculptures as per post #571 and hung in midair.
Building into that small a chassis was very difficult and required lots of planning.
Cheers,
Ian
Gary,
What I'm running in my lounge room right now is the schematic at post #602 and the power supply of post #603.
If using that small chassis then you won't have room BUT if chassis space is available I would recommend using polypropylene power supply caps (smaller values can be used). The effect is subtle.
Guys talk about amplifier PRATT (Pace Rhythm and Attack). The polyprops seem to slightly improve PACE and Rhythm.
I had one of the nieces BH amps back for repair, the Jessica Amp (her brother dropped it and smashed a tube). It is a 6V6 + 6SL7 variant with a tube rectifier - so I had a good listen to remind myself of the amps changes over time and different builds. Jessica now has 2 anklebiters so I also fitted a top cover to it.
The circuit for the Jessica BH is at post #1262 and its power supply at post #1261 except that the 2H 200mA choke into 2 x 47uF/450V has been modified by using a split after the 2uF first cap followed by a 8H 150mA choke into a 60uF polypropyolene cap for each channel. It had just stunning loping pace. JJ Cale was glorious on that amp. I's attack and top end were not as good as teyh EL84 version at post #602. While the schematics were posted later in the thread it was actually an earlier incarnation to test if tube rectification was worthwhile (NO) and if polyproylene capacitors made a difference (YES).
Cheers,
Ian
What I'm running in my lounge room right now is the schematic at post #602 and the power supply of post #603.
If using that small chassis then you won't have room BUT if chassis space is available I would recommend using polypropylene power supply caps (smaller values can be used). The effect is subtle.
Guys talk about amplifier PRATT (Pace Rhythm and Attack). The polyprops seem to slightly improve PACE and Rhythm.
I had one of the nieces BH amps back for repair, the Jessica Amp (her brother dropped it and smashed a tube). It is a 6V6 + 6SL7 variant with a tube rectifier - so I had a good listen to remind myself of the amps changes over time and different builds. Jessica now has 2 anklebiters so I also fitted a top cover to it.
The circuit for the Jessica BH is at post #1262 and its power supply at post #1261 except that the 2H 200mA choke into 2 x 47uF/450V has been modified by using a split after the 2uF first cap followed by a 8H 150mA choke into a 60uF polypropyolene cap for each channel. It had just stunning loping pace. JJ Cale was glorious on that amp. I's attack and top end were not as good as teyh EL84 version at post #602. While the schematics were posted later in the thread it was actually an earlier incarnation to test if tube rectification was worthwhile (NO) and if polyproylene capacitors made a difference (YES).
Cheers,
Ian
Thanks!
Hi Ian, thanks for your help! I pulled the back cover off the chinese unit I intended to build a BH into and you're right - it's certainly quite tight. The wiring on the inside is excellent as well - far better a job than I've ever done! So the end result is I'm going to have to find another donor unit to build a bh into.
Back to the drawing board then...
Hi Ian, thanks for your help! I pulled the back cover off the chinese unit I intended to build a BH into and you're right - it's certainly quite tight. The wiring on the inside is excellent as well - far better a job than I've ever done! So the end result is I'm going to have to find another donor unit to build a bh into.
Back to the drawing board then...
Ian.
Do you have any thoughts or preference on the types of tubes you have used in the input and output stage? What are you using now - NOS or new manufacture? If NOS , do you have any preferred favourites for the BH or if new manufacture what tube is your recommendation. I have some Hashimoto (Sansui) HW-15-8 OPT's I will use, which I got cheap a few years or so ago - much more expensive now I see.
Regards
Gary..
Do you have any thoughts or preference on the types of tubes you have used in the input and output stage? What are you using now - NOS or new manufacture? If NOS , do you have any preferred favourites for the BH or if new manufacture what tube is your recommendation. I have some Hashimoto (Sansui) HW-15-8 OPT's I will use, which I got cheap a few years or so ago - much more expensive now I see.
Regards
Gary..
I've been using JJ EL84 and NOS 12AX7 from the Philips Hendon factory here in Adelaide. NOS Tubes I've used:
JJ ECC803S but had to select from a batch for matched triodes.
ElectroHarmonix ECC83/12AX7 were better with regrads to the matching between triodes
For the 6V6 / 6SL7 version I've been using 6V6G from the Sydney AWV factory and Philips ECG 6SL7 but I have heaps of old stock of both 6V6G and 6SL7 to chose from.
Cheers,
Ian
JJ ECC803S but had to select from a batch for matched triodes.
ElectroHarmonix ECC83/12AX7 were better with regrads to the matching between triodes
For the 6V6 / 6SL7 version I've been using 6V6G from the Sydney AWV factory and Philips ECG 6SL7 but I have heaps of old stock of both 6V6G and 6SL7 to chose from.
Cheers,
Ian
Mach1,
The schematic at post #604 with the feedback taken from the UL taps was good so long as I linearised the frequency vs impedance of the speaker loads with "zobel" networks across the speakers. Otherwise the #602 schematic with feedback take from teh Output Tube anodes was better and other builders also reported that they preferred the #602 arrangement.
Cheers,
Ian
The schematic at post #604 with the feedback taken from the UL taps was good so long as I linearised the frequency vs impedance of the speaker loads with "zobel" networks across the speakers. Otherwise the #602 schematic with feedback take from teh Output Tube anodes was better and other builders also reported that they preferred the #602 arrangement.
Cheers,
Ian
Schoolboy error. That is with no load. I suppose it will drop under load. I was just identifying the windings having shelved the project for a couple of years. If the voltage remains too high can I put a couple of diodes in to drop the AC a bit? If so should they go after the 2 resistors connected to the HT centre tap (if you understand).
Will using both windings, one for each channel contribute to better channel separation?
Also my OPT's have 4 and 8 ohm windings, which winding should the feedback be connected to or best to experiment for best results?
Thanks.
Will using both windings, one for each channel contribute to better channel separation?
Also my OPT's have 4 and 8 ohm windings, which winding should the feedback be connected to or best to experiment for best results?
Thanks.
Last edited: