Does anybody have any experience with the Edcor line-level transformers for using at the input of an amplifier? I'm getting ready to build up (another) Heretical Preamp, and I'm actually going to use a transformer this time, since this will be a source selector and volume control for all of my inputs. Cinemag and Lundahl are way over the budget.
I saw that they have the PC and PCW series, max input of 5VRMS and 20VRMS respectively, bandwidth of 20-20kHz at <.05% THD, and they come in many different impedances, I would likely go for the 10k or 15k, and both feture center tapped primary and secondary. The only apparent difference in these two models appears to be power rating and price, at $6.95, and $11.05 respectively.
PC series
PCW series
There is also the WSM series- 10VRMS maximum input, 20-20Khz with THD of .05%, and its only $10.96.
WSM
The next step up that I see as suitable is the XS1100, max input of 7.5VRMS, edcor states in the description: "2+2:1+1 ratio matching transformer. An alternative to the LL5402 and compatible transformers." It is rated at 10~50K Hz, with THD <0.01%, and is $24.02. I would assume i could run the primaries in parallel for a 1-1 ratio, but low-signal level transformers are uncharted territory for me.
XS1100
Are there any other suitable transformers around a maximum of ~$30 each, that would be suitable? At this point I'm leaning towards the WSM for simplicity, but the lower frequency limit of 10hz and slightly better THD sounds like a benefit, but I'm not sure it's needed.
Since I'm not in familiar territory I could use a push in the right direction...
I saw that they have the PC and PCW series, max input of 5VRMS and 20VRMS respectively, bandwidth of 20-20kHz at <.05% THD, and they come in many different impedances, I would likely go for the 10k or 15k, and both feture center tapped primary and secondary. The only apparent difference in these two models appears to be power rating and price, at $6.95, and $11.05 respectively.
PC series
PCW series
There is also the WSM series- 10VRMS maximum input, 20-20Khz with THD of .05%, and its only $10.96.
WSM
The next step up that I see as suitable is the XS1100, max input of 7.5VRMS, edcor states in the description: "2+2:1+1 ratio matching transformer. An alternative to the LL5402 and compatible transformers." It is rated at 10~50K Hz, with THD <0.01%, and is $24.02. I would assume i could run the primaries in parallel for a 1-1 ratio, but low-signal level transformers are uncharted territory for me.
XS1100
Are there any other suitable transformers around a maximum of ~$30 each, that would be suitable? At this point I'm leaning towards the WSM for simplicity, but the lower frequency limit of 10hz and slightly better THD sounds like a benefit, but I'm not sure it's needed.
Since I'm not in familiar territory I could use a push in the right direction...
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I used the WSM10k:150 for a parafeed headphone amp output and it sounded pretty decent. I've also seen it used as "differential" output (Bruce Heran 6DJ8 headphone design).
I'm planning on trying a couple for inputs on a differential amp at some point soon (someone else already built the design and said it sounds great). The design is similar to the Lynn Olsen Raven preamp (input transformer -> differential tube -> output transformer).
I'm planning on trying a couple for inputs on a differential amp at some point soon (someone else already built the design and said it sounds great). The design is similar to the Lynn Olsen Raven preamp (input transformer -> differential tube -> output transformer).
Sounds good to me.
Just ordered a pair of the WSM 10k-10k. Total of $36.81 shipped ain't too bad, although shipping cost is a bit high when you only need a couple parts.
Now to grab a stepped attenuated, although a motorised pot and remote sounds like a nice addition to the project, might have to start looking into pairing this up with an LCDuino...
I'm reasonably convinced the Edcor will be lower distortion than 98% of anything that I would be putting after it for power amps.
I bit the bullet and ordered up an LCDuino board, 100k Alps motorpot (stereo audio taper) and enough parts to stuff two LCDuino boards. This will be a very fun project to build up with the heretical preamp as the buffer
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May I ask, where exactly is the heresy in the 'heretical' preamp?
It seems like a pretty work-a-day implementation to me, with the exception of a solid-state BJT-based CCS rather than a triode or pentode-based CCS. And as with any stage of this type, the main hobble is that flogging big output coupling cap.. And the anti-thump circuit is useless, unless you're the sort of knob who likes to power up a pre on a hot power amp.
Caps have artifact - and for a given design and composition, that artifact increases as the square (?) of the value. IOW, I don't see much advantage in this design over something like the 'simple SN7' (or AU7) line-stage. Sure, you get a CCS, and that's a good thing - but CCS are nothing new - even solid-state CCS in tube circuits.
It seems like a pretty work-a-day implementation to me, with the exception of a solid-state BJT-based CCS rather than a triode or pentode-based CCS. And as with any stage of this type, the main hobble is that flogging big output coupling cap.. And the anti-thump circuit is useless, unless you're the sort of knob who likes to power up a pre on a hot power amp.
Caps have artifact - and for a given design and composition, that artifact increases as the square (?) of the value. IOW, I don't see much advantage in this design over something like the 'simple SN7' (or AU7) line-stage. Sure, you get a CCS, and that's a good thing - but CCS are nothing new - even solid-state CCS in tube circuits.
Looks like a solid and well thought out design, I see no heresy. Many don't like cathode follower circuits, and don't like the use of sand in tube circuits, but no big deal to me. The DC servo version is a great solution to that big honking cap too.
Maybe I'll build this one up with a 6111 subminiature tube, nice specs on these little dudes.
Edcor just sent me a tracking number, and shipping notification. That was much sooner than expected
I'm thinking of calling my preamp/source selector Blasphemy, since it will have a LCDuino input/output selector with remote control/microcontroller processor for display, a motorised pot, relays for input selection, and the input to the pots will be transformer isolated and buffered by the Heretical. Should be pretty fun!
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