vht/fryette phase inverter???
Moderators: pompeiisneaks, Colossal
vht/fryette phase inverter???
i am trying to "clone" the fryette 2/90/2 and make a few changes to pair it with a pre section to make a custom amp head.
with no schematic available, i am stuck trying to reverse engineer this thing from the pcb.......and with only a beginners understanding of guitar amps.
at the same time ive been researching different types of phase inverters, how they work, what they do...etc.
i was wondering does anyone here know what kind of phase inverter setup this amp is using?
the amp uses:
2x 12ax7 for phase inverter
2x 12au7 for driver
4x kt88 for output
again, with my limited knowledge, i believe i can rule out split load/cathodyne because that would only use 1/2 of the 12ax7(correct?) and if that was the case they would only use 1 12ax7 tube in the amp instead of 2.
so im left with paraphase or long tailed pair, opinions?
any other info on the circuit would be greatly appreciated......
with no schematic available, i am stuck trying to reverse engineer this thing from the pcb.......and with only a beginners understanding of guitar amps.
at the same time ive been researching different types of phase inverters, how they work, what they do...etc.
i was wondering does anyone here know what kind of phase inverter setup this amp is using?
the amp uses:
2x 12ax7 for phase inverter
2x 12au7 for driver
4x kt88 for output
again, with my limited knowledge, i believe i can rule out split load/cathodyne because that would only use 1/2 of the 12ax7(correct?) and if that was the case they would only use 1 12ax7 tube in the amp instead of 2.
so im left with paraphase or long tailed pair, opinions?
any other info on the circuit would be greatly appreciated......
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- Joined: Wed May 14, 2014 11:40 am
Re: vht/fryette phase inverter???
Its probably 12ax7 first stage and cathodyne,12au7 as buffer/amplifier to the power tubes control grids.
Typical HiFi.
Typical HiFi.
Re: vht/fryette phase inverter???
This is a stereo 100 watts per channel multi-mode power amp and you're looking to add a pre-amp etc to it?
That seems a seriously complex project!
Page 20 of http://www.mif.pg.gda.pl/homepages/fran ... 88_GEC.pdf shows a 100watt KT88 amp
How about putting it on the back burner and building a Champ type amp first, to develop your skills and understanding?
That seems a seriously complex project!
Page 20 of http://www.mif.pg.gda.pl/homepages/fran ... 88_GEC.pdf shows a 100watt KT88 amp
How about putting it on the back burner and building a Champ type amp first, to develop your skills and understanding?
My band:- http://www.youtube.com/user/RedwingBand
Re: vht/fryette phase inverter???
[img:350:350]http://images.sodahead.com/polls/003645 ... large.jpeg[/img]
[img:500:389]http://www.impactlab.com/wp-content/upl ... ew-764.jpg[/img]
[img:500:389]http://www.impactlab.com/wp-content/upl ... ew-764.jpg[/img]
I build and repair tube amps. http://amps.monkeymatic.com
Re: vht/fryette phase inverter???
I wished I still owned his purple 2150 big brother.
TM
TM
Re: vht/fryette phase inverter???
thats the plan!!!xtian wrote:[img:350:350]http://images.sodahead.com/polls/003645 ... large.jpeg[/img]
[img:500:389]http://www.impactlab.com/wp-content/upl ... ew-764.jpg[/img]
@pdf64, im planning on only building one channel of the amp. i feel like if i had a schematic that i could handle it. maybe i will start off with a simpler build tho.....
@frankdrebin, ill check some hifi schematics and see if that helps me figure it out.
ive got all the components mapped and the traces on the bottom of the board but i cant follow the traces on the top of the board because they're hidden under a couple big filter caps. maybe ill remove them and finish mapping
Re: vht/fryette phase inverter???
this is what fryette says about it.....
V1 Input Stage (post volume control).
12AX7 China Phase Inverter.
12AX7WA Russia
V2 Voltage Amp/Driver Stage
12AU7 China Voltage Amp/Driver Stage
V3 Input Stage (post volume control).
12AX7 China Phase Inverter.
12AX7WA Russia
V4 Voltage Amp/Driver Stage
12AU7 China Voltage Amp/Driver Stage
V5-V8 Power Tubes
KT88 Sovtek
KT88 EH
KT88 Svetlana (SED)
so, v1a is the input stage, v1b is the phase inverter, v2a is voltage amp, and v2b is driver......
V1 Input Stage (post volume control).
12AX7 China Phase Inverter.
12AX7WA Russia
V2 Voltage Amp/Driver Stage
12AU7 China Voltage Amp/Driver Stage
V3 Input Stage (post volume control).
12AX7 China Phase Inverter.
12AX7WA Russia
V4 Voltage Amp/Driver Stage
12AU7 China Voltage Amp/Driver Stage
V5-V8 Power Tubes
KT88 Sovtek
KT88 EH
KT88 Svetlana (SED)
so, v1a is the input stage, v1b is the phase inverter, v2a is voltage amp, and v2b is driver......
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Re: vht/fryette phase inverter???
Is this the amp you had me modify ? If so , I recall you were only using one side.
If that is the case I would build the one on pg 16 of the link pdf64 referred you too.
with that preamp and power amp , you are not getting much distortion from the power amp. So just build a clean power full kt 88 power amp, like pg 16 shows. 50w. If you want a 100+w amp then build a marshall major , hiwatt 200, sound city lb200 etc. or an old style acrosound, there are lots of possibilities.
If that is the case I would build the one on pg 16 of the link pdf64 referred you too.
with that preamp and power amp , you are not getting much distortion from the power amp. So just build a clean power full kt 88 power amp, like pg 16 shows. 50w. If you want a 100+w amp then build a marshall major , hiwatt 200, sound city lb200 etc. or an old style acrosound, there are lots of possibilities.
Re: vht/fryette phase inverter???
@billyz, i got a new one. i had to sell that one to cover some bills.
i will start looking at some easier builds for someone at my level.
i still do want to figure out the schematic for this tho.... so i have it when i am ready to make this
i will start looking at some easier builds for someone at my level.
i still do want to figure out the schematic for this tho.... so i have it when i am ready to make this
Re: vht/fryette phase inverter???
does this look right if i want to diode rectify the champ circuit?
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Re: vht/fryette phase inverter???
No ! , that is a bridge rectifier. Just make it like a standard Fender SS Diode circuit.
Look up the AB763 schematic, say for a bandmaster . Its easy to do and you could do it with a tube rectifier socket even and have it switchable from tube to SS . I have done it with just one 1n4007 per side, but two in series per side might be better( safer ). Fender used 3 per side.
Look up the AB763 schematic, say for a bandmaster . Its easy to do and you could do it with a tube rectifier socket even and have it switchable from tube to SS . I have done it with just one 1n4007 per side, but two in series per side might be better( safer ). Fender used 3 per side.
- martin manning
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Re: vht/fryette phase inverter???
Spend some time here: http://www.valvewizard.co.uk
Re: vht/fryette phase inverter???
checking out champ kits to see which one i want.
in the mean time, ive figured out a lot on the vht circuit. i might have it mostly converted to schematic by tomorrow.....well see.
in the mean time, ive figured out a lot on the vht circuit. i might have it mostly converted to schematic by tomorrow.....well see.
Re: vht/fryette phase inverter???
[img:500:389]http://www.impactlab.com/wp-content/upl ... ew-764.jpg[/img][/quote]
That's a mean little lizard. Glad the dinosaurs are extinct.
That's a mean little lizard. Glad the dinosaurs are extinct.
Suggest you think about a cab made for 10, even a 12, unless the tiny portable thing has more appeal. 5F1 is where it's at IMO. Put the bypass cap on v1.Gorhrut wrote:checking out champ kits to see which one i want.
Re: vht/fryette phase inverter???
If you're using a PT intended for a Champ, then best to keep with a 5Y3 rectifier.checking out champ kits to see which one i want
If Si diodes were subbed in, the VB+ would increase significantly, thereby opening a can of worms.
My band:- http://www.youtube.com/user/RedwingBand