Hi all,
So I just bought 50 tip31c transistors for not much. Who wants to suggest a build for em?
Constraints....
I'd like to build a stereo pair.
The heatsinks are pretty... ummm, ghetto. Photos to follow...
The tip31C are to be the only power transistors. Small bjt's and jfets are fine (assuming I have em)
Minimal adjustment! I'm doing this as a 'get over your finicky builds' exercise, so I'd like to just smash it out on a breadboard and away we go.
Be creative... LEDs? Go for it - I've thousands. Bulk paralleling? Sure, go nuts!
No power supply constraints - I've enough transfo's here to improvise my way up to most voltages...
I reckon I'd like to have a design by the Friday, and I could knock out a proto on the weekend...
So.... go for it!
So I just bought 50 tip31c transistors for not much. Who wants to suggest a build for em?
Constraints....
I'd like to build a stereo pair.
The heatsinks are pretty... ummm, ghetto. Photos to follow...
The tip31C are to be the only power transistors. Small bjt's and jfets are fine (assuming I have em)
Minimal adjustment! I'm doing this as a 'get over your finicky builds' exercise, so I'd like to just smash it out on a breadboard and away we go.
Be creative... LEDs? Go for it - I've thousands. Bulk paralleling? Sure, go nuts!
No power supply constraints - I've enough transfo's here to improvise my way up to most voltages...
I reckon I'd like to have a design by the Friday, and I could knock out a proto on the weekend...
So.... go for it!
Hi Aspringv,
What output power do you have in mind?
What kind of speakers will you drive? What is their nominal impedance?
Cheers,
Valery
Theres a few choices...
Ok, I've a set of Clabby's (fullranger, tapped horn, 95dB, 8R) a set of TL6's from The Loudspeaker Kit (transmission line, MTM, 89.5dB sensitivity, 6R). Probably a build for the TL6's would be preferred, given I currently drive them with a home made Class D module from sure electronics...
Edit - Power output? No idea - happy to see what happens in all honesty!
Edit Edit - probably governed by the upper limit of supply caps I have on hand... 63V
Ok, I've a set of Clabby's (fullranger, tapped horn, 95dB, 8R) a set of TL6's from The Loudspeaker Kit (transmission line, MTM, 89.5dB sensitivity, 6R). Probably a build for the TL6's would be preferred, given I currently drive them with a home made Class D module from sure electronics...
Edit - Power output? No idea - happy to see what happens in all honesty!
Edit Edit - probably governed by the upper limit of supply caps I have on hand... 63V
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What do you have in stock in terms of TO-126 drivers and high-voltage transistors?
TIP31C are 4 amp jobs, so you'll want to parallel 2-3 pairs or so. Vceo is 100V, so unless cascoding, supplies should be ~+/-45 V max.
I'd go for something ESP P3A-ish (though maybe with the frontend upside down, i.e. pnp inputs and npn VAS). You only have to thermally couple drivers and bias spreader transistor when using a CFP output stage, which may come in handy. Dimension output resistors for some decent quiescent current in these rather slow outputs (expect <0.1 ohms), don't forget current sharing resistors in the emitter leads (0.1-ish ohms?).
TIP31C are 4 amp jobs, so you'll want to parallel 2-3 pairs or so. Vceo is 100V, so unless cascoding, supplies should be ~+/-45 V max.
I'd go for something ESP P3A-ish (though maybe with the frontend upside down, i.e. pnp inputs and npn VAS). You only have to thermally couple drivers and bias spreader transistor when using a CFP output stage, which may come in handy. Dimension output resistors for some decent quiescent current in these rather slow outputs (expect <0.1 ohms), don't forget current sharing resistors in the emitter leads (0.1-ish ohms?).
to-126? BD139, BD140 is what I've on hand...
Both solid suggestions - I've most of a DOZ finished, so doing the JLH seems a waste...
ESP-P3A uses complimentary output BJT's... doesn't it?
Both solid suggestions - I've most of a DOZ finished, so doing the JLH seems a waste...
ESP-P3A uses complimentary output BJT's... doesn't it?
Hmmmm, what about the attached... scaled down a bit 🙂 and lots of paralleling of outputs.
Edit - credit to https://sites.google.com/site/quasisdiyaudiosite/nbip-series/nbip300 for the design. Those ghetto sinks would be in use if i was better at toner transfers...
Oh, and I've a stack of 0R15 5W resistors, so paralleling a pair is easy enough.
Edit - credit to https://sites.google.com/site/quasisdiyaudiosite/nbip-series/nbip300 for the design. Those ghetto sinks would be in use if i was better at toner transfers...
Oh, and I've a stack of 0R15 5W resistors, so paralleling a pair is easy enough.
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Looks like a reasonable start, although with those output devices you should limit the rails to about +/- 40V.
Left to right:
- C1 polyester or polypropylene film
- Match R5 & R10 as well as R4 and R9. Eliminate VR1
- Start conservative with Cdom - start with about 100pF.
- Select a better transistor type for the VAS (T6) if available
Left to right:
- C1 polyester or polypropylene film
- Match R5 & R10 as well as R4 and R9. Eliminate VR1
- Start conservative with Cdom - start with about 100pF.
- Select a better transistor type for the VAS (T6) if available
For your TL, the power from a pair of IRFP240/9240's with 35v rail would be perfectly adequate. However, since you say you have 63v caps, you can switch the BD139/140's to KSC3503/KSA1381 and power with 53v rails for 120w amp. It sounds fantastic for how simple of an amp it is. Those ghetto heatsinks are a great idea - would be perfect. It's such a simple amp - and can be built in a few hours. Several confirmed builds now and all reports are that it sounds great. Measurements of a speaker also look very good.
http://www.diyaudio.com/forums/solid-state/164093-100w-ultimate-fidelity-amplifier-790.html
FH9 HV:
Here it is driving dummy load at 120w:
Here is the non HV version (BD139/140 drivers) with 35v rail supply. Sounds very good - deep powerful bass, smooth mids and clear non fatiguing highs.
http://www.diyaudio.com/forums/solid-state/164093-100w-ultimate-fidelity-amplifier-790.html
FH9 HV:
Here it is driving dummy load at 120w:
Here is the non HV version (BD139/140 drivers) with 35v rail supply. Sounds very good - deep powerful bass, smooth mids and clear non fatiguing highs.
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I like it!
Any documentation there around that guy? And I guess I can scale that up a bit...
I've actually completed a DOZ (jlh variant) and regulated supplies... and never finished it (I did learn how big heatsinks needed to be though!) So I might go for something a bit different this time. 🙂
Thanks for the suggestions though! That's nearly it tonight, so I'm curious to see what tomorrow brings in terms of suggestions. 🙂
Thanks for the suggestions though! That's nearly it tonight, so I'm curious to see what tomorrow brings in terms of suggestions. 🙂
Ampli-TIP
OK, I have re-designed the OPS of VHex current-drive design, making it quasi-complementary.
At +/-36V DC rails, you will have up to 50W at 8 ohm load.
I have also changed all TO-126 ones to BC139/140 for your convenience, however, 2sc3503/a1381 will give lower distortion at higher end of the audio bandwidth. With BD139/140 THD1 < 0.02%, THD20 < 0.05% (simulated values at 30W at the output). Stability margins are good (phase margin = 88 deg, gain margin = 18.5 db).
For the layout, you can take a VHex single-layer one and modify its output part.
What do you think?
Cheers,
Valery
OK, I have re-designed the OPS of VHex current-drive design, making it quasi-complementary.
At +/-36V DC rails, you will have up to 50W at 8 ohm load.
I have also changed all TO-126 ones to BC139/140 for your convenience, however, 2sc3503/a1381 will give lower distortion at higher end of the audio bandwidth. With BD139/140 THD1 < 0.02%, THD20 < 0.05% (simulated values at 30W at the output). Stability margins are good (phase margin = 88 deg, gain margin = 18.5 db).
For the layout, you can take a VHex single-layer one and modify its output part.
What do you think?
Cheers,
Valery
Attachments
That's pretty wild qnty 8 x TIP31's! 😀
But an IRFP240/9240 pair is $4.50 from Digikey and $6 for 5 pairs (confirmed genuine Vishay) from Aliexpress.
But an IRFP240/9240 pair is $4.50 from Digikey and $6 for 5 pairs (confirmed genuine Vishay) from Aliexpress.
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Well, building a VHex+, for example, would be an easy way to go 🙂
The codition was - TIP31C. Not as good, but possible 😉
Or something like this one from Pass Labs: https://www.passdiy.com/project/amplifiers/construct-a-class-a-amplifier. And then increase the number of output transistors or lower the voltage.
Even less given I've them on hand!
That said the idea was to make something out of a random ish purchase - hence the tip31c criteria. I've a nice fetzilla build and a F5 here so FETs are covered off in my household already 🙂
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