Got the replacement boards today. Thanks Peter. At last got the F5 working again. Very very nice sound. IMHO it has A Wonderful presence to it, like the gainclone. Gainclone perhaps has even more presence to it, allowing even poorer recordings to sound good?? albeit with a slightly leaner tone but not by much mind you. Love both of them. Neither to me sound like typical valve or solid state they just sound RIGHT and ACCURATE.
The combination of these amps with the shigaclone (including the Bybee's) tda 1543 dac, and an LDR attenuator are quite simply mesmerising at times with the realism they portray.
What next, F3 and B1 Buffer???
I have sold all my high end stuff since starting this DIY hobbie, as they are simply better. Jadis JPS2 preamp gone, audio note P4 300B silver signature P4's gone,Jadis JA80's gone, Audionote M5 gone, Audionote transport and DAC 4 gone.Atmasphere otl gone, cec tl2 gone, Revox b225 gone,etc etc Some of their diy counterparts have cost me about 1/100th of the price of some of them!!!!!
Thank you DIY AUDIO and Peter Daniel in particular.
Luke
The combination of these amps with the shigaclone (including the Bybee's) tda 1543 dac, and an LDR attenuator are quite simply mesmerising at times with the realism they portray.
What next, F3 and B1 Buffer???
I have sold all my high end stuff since starting this DIY hobbie, as they are simply better. Jadis JPS2 preamp gone, audio note P4 300B silver signature P4's gone,Jadis JA80's gone, Audionote M5 gone, Audionote transport and DAC 4 gone.Atmasphere otl gone, cec tl2 gone, Revox b225 gone,etc etc Some of their diy counterparts have cost me about 1/100th of the price of some of them!!!!!
Thank you DIY AUDIO and Peter Daniel in particular.
Luke
kp9330
photo is on post 110 on this thread.
Perhaps a little less conventional
4 toroids in a separate box, AC supply goes to the main chassis at the moment not DC.
Because in the Uk it is not so easy or cheap getting the chassis others seem to manage to find, i used an old P range Yamaha power amp chassis with extensive cooling elements already built in.
For good or bad some of my overrated dale resistors and Bournes Pots did not fit onto the board so were hard wired and the output mosfets had also to be hard wired onto the board because of the fixed nature of the chassis.
Used about 40000uf per channel so far not sure if I should add more at this stage. Peter's Power boards really helped make it easier to build and neater looking also. I have used chord rumour silver coated copper wiring for all connections from the dc outputs onwards. that is power supply leads, earthing leads hard wiring the various components and speaker outputs. I intend to use this for the ac line, from the power supply box all the way to the power supply boards and have them screened also. At the moment that task is carried out using simple standard mains impure copper wiring. VDH Hybrid screened cable for the input signal was used, which will add greatly to any tonal colours that the amp can provide. Boy as it continues to burn in i am getting more and more pleasantly surprised by the sheer tonal range this amp is able to provide giving wonderful emotion and detail to voices. Dare I say this, I think i will.... even the best bottled amps are now beginning to sound coloured.... there i have said it.
photo is on post 110 on this thread.
Perhaps a little less conventional
4 toroids in a separate box, AC supply goes to the main chassis at the moment not DC.
Because in the Uk it is not so easy or cheap getting the chassis others seem to manage to find, i used an old P range Yamaha power amp chassis with extensive cooling elements already built in.
For good or bad some of my overrated dale resistors and Bournes Pots did not fit onto the board so were hard wired and the output mosfets had also to be hard wired onto the board because of the fixed nature of the chassis.
Used about 40000uf per channel so far not sure if I should add more at this stage. Peter's Power boards really helped make it easier to build and neater looking also. I have used chord rumour silver coated copper wiring for all connections from the dc outputs onwards. that is power supply leads, earthing leads hard wiring the various components and speaker outputs. I intend to use this for the ac line, from the power supply box all the way to the power supply boards and have them screened also. At the moment that task is carried out using simple standard mains impure copper wiring. VDH Hybrid screened cable for the input signal was used, which will add greatly to any tonal colours that the amp can provide. Boy as it continues to burn in i am getting more and more pleasantly surprised by the sheer tonal range this amp is able to provide giving wonderful emotion and detail to voices. Dare I say this, I think i will.... even the best bottled amps are now beginning to sound coloured.... there i have said it.
Yes it is the irf 240 not matched them yet as initially all I wanted to do was to get the thing working, so obviously must be more room for improvement to come. You can get these mosfets matched and sold via ebay from the Far East.
As the sound is at present i would stick with the VDH carbon hybrid input signal cable as these have a very natural and 'seductive' midrange which i am presuming will best match solid state devices, will try others later. Pure silver IMO can lead to a less tonally rich sound albeit more detailed and hyperetched, but if screened and using polyurethane sleeves instead of teflon this would help greatly in that area. So I will give it a go later.
As the sound is at present i would stick with the VDH carbon hybrid input signal cable as these have a very natural and 'seductive' midrange which i am presuming will best match solid state devices, will try others later. Pure silver IMO can lead to a less tonally rich sound albeit more detailed and hyperetched, but if screened and using polyurethane sleeves instead of teflon this would help greatly in that area. So I will give it a go later.
f5-feedback mods per NP
Just thought I'd post my initial impressions of having modified the feedback network relative to Nelson's suggestion( R11 & 12 to 1 ohm/
R5 & R8 to 100 ohms and R1 & R2 to 22ohms-pass site)
Yep,Yep amp runs a little cooler(perhaps 8-10 degree farenheit) and the "tight fist" now has a velvet glove!
I found the oirginal spec a bit dry and etched in sound relative to my dynaco st70- accurate and detailed but lacking a bit of body or warmth. The new feedback seems to be a definite step in the right direction. This am I'm listening to Joni Mitchell "Court and Spark"(DCC issue) and on "Twisted" the trumpet is nicely placed behind Joni, edgy but not etched. I clearly hear her pushing the air from her sinuses, from her throat, from her chest depending on the note or the intended emphasis. Cheech and Chong sound like Cheech and Chong and perhaps they have been consuming some controled substances? Judge for yourselves, point is the sound is more relaxed. I have even turned my REL Strata sub down from a x-over point in the mid 40's to the high 30's- I don't need the extra warm. This is subtle but very indicative of the change from the feedback modification. Thanks for the suggestion Nelson. N.P. you won't have any measurement or o-scope shots of this feedback level relative to the original spec would you?
Thanks for your help in this.
Probably dumb question but here goes- two identical transformers wired in parallel(ac input joined together4 wires to 2/ ac output 8 wires to 4) gives me the same voltage and twice the amperage-yes,yes?
have a great weekend, you-all
rob
Just thought I'd post my initial impressions of having modified the feedback network relative to Nelson's suggestion( R11 & 12 to 1 ohm/
R5 & R8 to 100 ohms and R1 & R2 to 22ohms-pass site)
Yep,Yep amp runs a little cooler(perhaps 8-10 degree farenheit) and the "tight fist" now has a velvet glove!
I found the oirginal spec a bit dry and etched in sound relative to my dynaco st70- accurate and detailed but lacking a bit of body or warmth. The new feedback seems to be a definite step in the right direction. This am I'm listening to Joni Mitchell "Court and Spark"(DCC issue) and on "Twisted" the trumpet is nicely placed behind Joni, edgy but not etched. I clearly hear her pushing the air from her sinuses, from her throat, from her chest depending on the note or the intended emphasis. Cheech and Chong sound like Cheech and Chong and perhaps they have been consuming some controled substances? Judge for yourselves, point is the sound is more relaxed. I have even turned my REL Strata sub down from a x-over point in the mid 40's to the high 30's- I don't need the extra warm. This is subtle but very indicative of the change from the feedback modification. Thanks for the suggestion Nelson. N.P. you won't have any measurement or o-scope shots of this feedback level relative to the original spec would you?
Thanks for your help in this.
Probably dumb question but here goes- two identical transformers wired in parallel(ac input joined together4 wires to 2/ ac output 8 wires to 4) gives me the same voltage and twice the amperage-yes,yes?
have a great weekend, you-all
rob
f5-excluding the thyristors-TH1&TH2
Howdy campers
am about to build my second set of PD F5 boards and am planning on not using the current limiting and using a lower feedback per NP.
The question de jour;
I assume since TH1 &TH2 bring the voltage to R15 & R16 that you would need to use a jumper across the thru holes from the deleted thyristors to complete the circuit.
Also am I correct in assuming that you would just delete Q5,R17,R19 and R21 and Q6,R18,R20, and R22 to delete the current limiting from the circuit? No jumpers needed?
thanks for your "eyes"
rob
Howdy campers
am about to build my second set of PD F5 boards and am planning on not using the current limiting and using a lower feedback per NP.
The question de jour;
I assume since TH1 &TH2 bring the voltage to R15 & R16 that you would need to use a jumper across the thru holes from the deleted thyristors to complete the circuit.
Also am I correct in assuming that you would just delete Q5,R17,R19 and R21 and Q6,R18,R20, and R22 to delete the current limiting from the circuit? No jumpers needed?
thanks for your "eyes"
rob
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