Patrick
After such a lay off doing any electronics, this is pushing the boat out a little. I am currently ordering the parts for a NIGC. though no real challenge there.
With BP on the bridge doubling, my current speakers use a PA driver for bass nominally 4Ohm dipping to 2 ohms. The 7.5A I had in mind was a max giving ~3.6 ohm max. For my new speakers I had envisaged a minimum of 4.5 so would still be aiming at 6.5A bias.
In previous class A amps I have built (18 years ago) I found that not aiming for this low a minimum impedance has a noticable affect on the quality of the bass. speed, timing, rhythm all seemed very slow. At the time went for class B as being a drummer this is important to me and the class A option was to expensive for a student. Also needed it to go all the way to 11.
With this aim in mind i dont really want an extra couple of electric heaters in the lounge (Low WAF
) so could do with aiming for a lower rail voltage.
On this basis was working on +/- 12V trannys.
I am interested in experimenting with biamping the bass with a class D.(LCA audio/tripath ta0105 being the obvious), but not for now. Though could use this for the LOUD system by my drums. (1x12", 1x15" +horns per channel, 18" sub on the way!).
Hope this explains things better.
Simon
After such a lay off doing any electronics, this is pushing the boat out a little. I am currently ordering the parts for a NIGC. though no real challenge there.
With BP on the bridge doubling, my current speakers use a PA driver for bass nominally 4Ohm dipping to 2 ohms. The 7.5A I had in mind was a max giving ~3.6 ohm max. For my new speakers I had envisaged a minimum of 4.5 so would still be aiming at 6.5A bias.
In previous class A amps I have built (18 years ago) I found that not aiming for this low a minimum impedance has a noticable affect on the quality of the bass. speed, timing, rhythm all seemed very slow. At the time went for class B as being a drummer this is important to me and the class A option was to expensive for a student. Also needed it to go all the way to 11.
With this aim in mind i dont really want an extra couple of electric heaters in the lounge (Low WAF
) so could do with aiming for a lower rail voltage. On this basis was working on +/- 12V trannys.
I am interested in experimenting with biamping the bass with a class D.(LCA audio/tripath ta0105 being the obvious), but not for now. Though could use this for the LOUD system by my drums. (1x12", 1x15" +horns per channel, 18" sub on the way!).
Hope this explains things better.
Simon
Hi mark,
Not a problem for me on the postage side of things. I get the Manger 103s at the end of March, but only for three weeks cause they're going off to be reviewed by HiFi News straight after I have them.
D3, Paypal is not a problem at all!
Thanks,
Gaz
Not a problem for me on the postage side of things. I get the Manger 103s at the end of March, but only for three weeks cause they're going off to be reviewed by HiFi News straight after I have them.
D3, Paypal is not a problem at all!
Thanks,
Gaz
15V, 8A bias
Simon,
Sorry, I take everything back.
If your speakers are 4 ohm nominal, then high bias make sense. In that case you should use 044's and not 240's. 15V would be fine, but I would definitely not go under 1.8A per FET. In the end, the heat dissipation and temperature rise per heat sink size is the same whether you use 6 or 8 FET's. The only thing you need to watch is actual FET junction temperature; i.e. if you use 6 FET's instead of 8 (for example), make sure you have very good contact between FET and sink, and very substantial sinks (like 2 pieces of 0.07 C/W). And do some simple maths to estimate junction temperature.
Patrick
Simon,
Sorry, I take everything back.
If your speakers are 4 ohm nominal, then high bias make sense. In that case you should use 044's and not 240's. 15V would be fine, but I would definitely not go under 1.8A per FET. In the end, the heat dissipation and temperature rise per heat sink size is the same whether you use 6 or 8 FET's. The only thing you need to watch is actual FET junction temperature; i.e. if you use 6 FET's instead of 8 (for example), make sure you have very good contact between FET and sink, and very substantial sinks (like 2 pieces of 0.07 C/W). And do some simple maths to estimate junction temperature.
Patrick
044's or 240's
One more point, Simon,
I have not yet tested both (am planning to), but the linearity of each transistor at working point depends of course on the bias current. You need much more current for 044's than 240's to get it in the linear region, so 044's are really only for low rail voltages, IMHO.
Patrick
One more point, Simon,
I have not yet tested both (am planning to), but the linearity of each transistor at working point depends of course on the bias current. You need much more current for 044's than 240's to get it in the linear region, so 044's are really only for low rail voltages, IMHO.
Patrick
capacitors
Order for caps placed........100 are being ordered
Will keep you posted on cost etc....
Order for caps placed........100 are being ordered
Will keep you posted on cost etc....
Patrick
Thanks ... for the info, still getting to grips with it all again. I still need to get the 044 specs fully understood (could take some time) and calculate the thermals through to check out the thermals. The spreadsheet only allows multiples of 4 for the FETs and I cannot see how to do 6 because of the circuit symmetry. This keeps the bias per fet down or have to crank bias up to 9-10 amps or so.
Has anyone used the duncan amps PSU designer for any of their PSU's? if so did which diode did you use or did you input the BTW200 ones. Looking to get a handle for the tranny voltages.
Aiming at 14-15V on rails after 408mF per channel. Any recommendations CRC or CLC?
D3 please can you confirm last days to spec the transformers?
The usual busy weekend ahead- builders in, putting in a new velux, and for myself putting a new gas control unit on the AGA. Oh the joys of DIY.....The price for an uninterupted viewing of the last episode of series 7 of Stargate. At gets better with age or is me getting older!
Have a good weekend all.
Simon
Thanks ... for the info, still getting to grips with it all again. I still need to get the 044 specs fully understood (could take some time) and calculate the thermals through to check out the thermals. The spreadsheet only allows multiples of 4 for the FETs and I cannot see how to do 6 because of the circuit symmetry. This keeps the bias per fet down or have to crank bias up to 9-10 amps or so.
Has anyone used the duncan amps PSU designer for any of their PSU's? if so did which diode did you use or did you input the BTW200 ones. Looking to get a handle for the tranny voltages.
Aiming at 14-15V on rails after 408mF per channel. Any recommendations CRC or CLC?
D3 please can you confirm last days to spec the transformers?
The usual busy weekend ahead- builders in, putting in a new velux, and for myself putting a new gas control unit on the AGA. Oh the joys of DIY.....The price for an uninterupted viewing of the last episode of series 7 of Stargate. At gets better with age or is me getting older!
Have a good weekend all.
Simon
Tranny Order
The spec still stands at 18-0-18 @ 230v 1000va ....potted with anti mag band.
I intend to order Trannys...... towards the end of March....I'm skint until then!!!
So there is time to discuss and alter spec a bit..........but I recon
the 18v solution should do in most cases,
The spec still stands at 18-0-18 @ 230v 1000va ....potted with anti mag band.
I intend to order Trannys...... towards the end of March....I'm skint until then!!!
So there is time to discuss and alter spec a bit..........but I recon
the 18v solution should do in most cases,
Hi All,
been away a few days.
D3, did you get my Cap confirmation email?
I saw you got Mrs C's reply on my behalf!!! 😉 😀
Cheers
Jon
(Don't be fooled - she thinks this DIYAudio lark is daft!! 🙄 )
been away a few days.
D3, did you get my Cap confirmation email?
I saw you got Mrs C's reply on my behalf!!! 😉 😀
Cheers
Jon
(Don't be fooled - she thinks this DIYAudio lark is daft!! 🙄 )
6 FET's
Simon,
Sorry. 6 FET's per side, i.e. 12 FET's per channel instead of 16 was what I meant (assuming 240's).
8 x 044's would of course give you somewhere around 8A bias total.
Patrick
Simon,
Sorry. 6 FET's per side, i.e. 12 FET's per channel instead of 16 was what I meant (assuming 240's).
8 x 044's would of course give you somewhere around 8A bias total.
Patrick
capacitors
I have ordered capacitors........................
I have ordered 100
That should be enough for all who requested.
(jonclancy.......this includes yours)
Once they have arrived I will calculate postage, cc percentage and
paypal deductions.............I am strictly non profit making.........
I will keep you guys informed
By the way KRAM have you got your heatsinks?????
D3
I have ordered capacitors........................
I have ordered 100
That should be enough for all who requested.
(jonclancy.......this includes yours)
Once they have arrived I will calculate postage, cc percentage and
paypal deductions.............I am strictly non profit making.........
I will keep you guys informed
By the way KRAM have you got your heatsinks?????
D3
Hi D3
Yes they arrived at my parents house on thursday and I didnt get a chance to see them until saturday.
They look good but seem smaller than I imagined them to be.
Thanks again D3, now looking forward to getting caps.
Mark.
Yes they arrived at my parents house on thursday and I didnt get a chance to see them until saturday.
They look good but seem smaller than I imagined them to be.
Thanks again D3, now looking forward to getting caps.
Mark.
Kram said:
That's what I thought upon seeing them, but then I thought, h'm perhaps more of these wouldn't have been too bad after all?
In fact, I am now planning on building up the x amps as two mono-blocks (rather than the single chassis as I originaly thought), in what may be one of the slimest designs about, with a main chassis height of only 75mm per channel.
Now, I just have to find an amp worthy of the two big MF35-151's I have left over...
Now, I just have to find an amp worthy of the two big MF35-151's I have left over...
capacitors
Right the caps are being posted out today.....from usa and should be delivered between 7 & 8 days.........
Cost so far is looking at around £4.15 a cap + delivery to your
address+any import duty+ paypal surcharge.
I am trying to get away with import duty..........I will keep you posted.
these caps are fantastic value.................cost in uk would be at least 3 times this.......us dollar to £ has really helped.😀 😀 😉 😉 😀 😀 😀 😀 😉 😉
Right the caps are being posted out today.....from usa and should be delivered between 7 & 8 days.........
Cost so far is looking at around £4.15 a cap + delivery to your
address+any import duty+ paypal surcharge.
I am trying to get away with import duty..........I will keep you posted.
these caps are fantastic value.................cost in uk would be at least 3 times this.......us dollar to £ has really helped.😀 😀 😉 😉 😀 😀
😀 😀 😉 😉Re: 6 FET's
Hi,
Sorry are sure, with the last ax calculation sheet I obtain 5A for 8x 044 under 1.25A for each Fet!
Alex
EUVL said:
Hi,
Sorry are sure, with the last ax calculation sheet I obtain 5A for 8x 044 under 1.25A for each Fet!
Alex
The amount of current running in the circuit has notthing (well not quite nothing) to do with how many transistors you have in the circuit. You could run at 10A with only the four (the minimum number you need) transistors if you could cool them well enough, but they would probably just blow up in most cases.
Idealy, what you want to is to look at your power dissipation for you own particular supply voltage and current bias, then from this, you can calculate how much each FET will be handling (e.g., if you have +/- 20V rails and a 5A bias you will get 200W total dissipation, which would lead to a rather hig value of 50W per device if you are using four FET's, ar a more reasonable 25W per device if you run 8), which idealy should be kept around 25W to keep the life of the devices at a reasonable level, without having too little current flowing in the transistors to keep them in their optimum opperating area.
Idealy, what you want to is to look at your power dissipation for you own particular supply voltage and current bias, then from this, you can calculate how much each FET will be handling (e.g., if you have +/- 20V rails and a 5A bias you will get 200W total dissipation, which would lead to a rather hig value of 50W per device if you are using four FET's, ar a more reasonable 25W per device if you run 8), which idealy should be kept around 25W to keep the life of the devices at a reasonable level, without having too little current flowing in the transistors to keep them in their optimum opperating area.
Fet cooling
Using the axe-1.xls and the IRFP044 spec sheet gives a transistor mounting to heatsink of 0.24 which gives a 50w max that could safely dissapated for the FET. With 9 amp bias over 8 Fets 33W each 270 per channel. The cooling I am aiming for is to dissapate 330w per channel. 20% margin.
XA 160 consumes 550W Axe-1 estimates for 27V 12.5A bias 650W per channel to dissapate?
End up with an XA42 on 15V. wishful thinking!
Simon
Using the axe-1.xls and the IRFP044 spec sheet gives a transistor mounting to heatsink of 0.24 which gives a 50w max that could safely dissapated for the FET. With 9 amp bias over 8 Fets 33W each 270 per channel. The cooling I am aiming for is to dissapate 330w per channel. 20% margin.
XA 160 consumes 550W Axe-1 estimates for 27V 12.5A bias 650W per channel to dissapate?
End up with an XA42 on 15V. wishful thinking!
Simon
UK Reichelt Group Order!!!
All participants in the UK Reichelt Group Order:
The list will close at 2359 on Saturday!!!
I repeat: 2359 on Saturday!!!
I will re-check the prices on the website after that, and will add the relevant PayPal fees and details of how to pay direct to Andrea (in EUROS). However, there will be a further post and packing payment required (to me) to release your parts. This will include a portion of the postage from Reichelt to Andrea and from him to me. I have ordered the padded envelopes and will be able to make up the orders and get them to the post office for pricing up.
I am intending to do "Signed For" deliveries - a little more expensive, but insured in case any go astray.
Unfortunately, we did not get anywhere near the 600 MOQ for the BYW99W-200, so I am afraid I cannot order them from the intended supplier (wasn't Reichelt).
More soon, but email me if you have any queries.
Cheers
Jon
All participants in the UK Reichelt Group Order:
The list will close at 2359 on Saturday!!!
I repeat: 2359 on Saturday!!!
I will re-check the prices on the website after that, and will add the relevant PayPal fees and details of how to pay direct to Andrea (in EUROS). However, there will be a further post and packing payment required (to me) to release your parts. This will include a portion of the postage from Reichelt to Andrea and from him to me. I have ordered the padded envelopes and will be able to make up the orders and get them to the post office for pricing up.
I am intending to do "Signed For" deliveries - a little more expensive, but insured in case any go astray.
Unfortunately, we did not get anywhere near the 600 MOQ for the BYW99W-200, so I am afraid I cannot order them from the intended supplier (wasn't Reichelt).
More soon, but email me if you have any queries.
Cheers
Jon
- Status
- Not open for further replies.