@wcwc
As written in few existing threads about this preamp, arrangements are well known, main criteria being ratio of IN/OUT impedances and solving them in best way:
-with regular resistive attenuator (whatever way it's made), there is source selector, then volume pot (value highest possible but not so high to invoke in game interconnect capacitances ), then buffer (Rin set to highest possible but not so high to invoke in game interelectrode capacitances of used parts)
-with AVC/TVC there is source selector, then buffer (Rin set to value highest possible but not so high to invoke in game interconnect capacitances), then AVC/TVC
Iron Pre is combo of these two, arrangement as with regular resistive attenuator, with Autoformer ( goal is gain) crudely glued to buffer output
Now, Iron Pre is having low enough Rout to feed your AVC, even if in different enclosure, accounting interconnects in game
Best scenario is to assemble Iron Pre without autoformer, shorting appropriate pads (shown somewhere back for someone not needing gain), from two reasons - Rout is lower, and better to arrange what you need of gain with AVC itself, principle shown in post #2113
now, that all for Iron Pre SE; as I said - I'm not aware of any commercially available proper balanced AVC - few I know of are sorta cheat - pair of regular SE AVC arranged to have physically common switching, which is having exactly zero of all benefits which proper differential/SUSY functionality gives
If you have proper one ( if I understood correctly that you intend to use Balanced ), I'm very interested in its origin/manufacture/type - always good to know what's on market (me not buyer but always eager to dig and learn)
As written in few existing threads about this preamp, arrangements are well known, main criteria being ratio of IN/OUT impedances and solving them in best way:
-with regular resistive attenuator (whatever way it's made), there is source selector, then volume pot (value highest possible but not so high to invoke in game interconnect capacitances ), then buffer (Rin set to highest possible but not so high to invoke in game interelectrode capacitances of used parts)
-with AVC/TVC there is source selector, then buffer (Rin set to value highest possible but not so high to invoke in game interconnect capacitances), then AVC/TVC
Iron Pre is combo of these two, arrangement as with regular resistive attenuator, with Autoformer ( goal is gain) crudely glued to buffer output
Now, Iron Pre is having low enough Rout to feed your AVC, even if in different enclosure, accounting interconnects in game
Best scenario is to assemble Iron Pre without autoformer, shorting appropriate pads (shown somewhere back for someone not needing gain), from two reasons - Rout is lower, and better to arrange what you need of gain with AVC itself, principle shown in post #2113
now, that all for Iron Pre SE; as I said - I'm not aware of any commercially available proper balanced AVC - few I know of are sorta cheat - pair of regular SE AVC arranged to have physically common switching, which is having exactly zero of all benefits which proper differential/SUSY functionality gives
If you have proper one ( if I understood correctly that you intend to use Balanced ), I'm very interested in its origin/manufacture/type - always good to know what's on market (me not buyer but always eager to dig and learn)
I picked up a Slagle AVC. I chose the $400 one on Intact Audios page that comes mounted to the circuit board. It is single ended. I was going to do the source switching and volume control single ended, since all my sources are single ended. Was going into the Iron Pre single ended. May come out balanced or single ended depending on the amp. So my Iron Pre is pretty empty looking with no relays and no volume control. I was just wondering if I should build it with the Cinemag transformer, since I have other resistive pots I could also use upstream of the pre for volume control.
Everyday is a good day
Every day I'm alive and in full control of my bowels is a fantastic day. I dread the day Numero Dos starts to behave like Numero Uno. Yikes!
I've been looking at getting a TVC since the 90s. All the balanced stereo TVC use four transformers. I have not seen anything different yet.
you can't use SE AVC with Balanced Iron Pre, simple as that
build preamp as is, with resistive attenuator of your choosing
wcwc,
you could use an input transformer at the input of your balanced amp to convert SE to Bal. I have used the Jensen JT11P1; very easy to connect and sounds excellent.
I have several DIY preamps with custom resistive attenuators in front and putting an AVC after the preamp(reasonable Rout) always sounds better to me. With a buffer before the AVC even better.
nash
you could use an input transformer at the input of your balanced amp to convert SE to Bal. I have used the Jensen JT11P1; very easy to connect and sounds excellent.
I have several DIY preamps with custom resistive attenuators in front and putting an AVC after the preamp(reasonable Rout) always sounds better to me. With a buffer before the AVC even better.
nash
I will just build the Iron Pre like my other preamps with no volume control and no input switching. Can always add later if I find it necessary.
I have some BTSB and THAT Driver boards that convert SE to Differential. The Iron Pre would give me the same capability on 2 channel setup. The other setups are multi-way speakers or a multi-channel setup.
I have some BTSB and THAT Driver boards that convert SE to Differential. The Iron Pre would give me the same capability on 2 channel setup. The other setups are multi-way speakers or a multi-channel setup.
correction:
you can use SE AVC in context of Iron Pre Bal, in two possible scenarios, both of these enabling deleting of regular resistive attenuator, both of these dictating output autoformer in place
1. if strictly using SE inputs, AVC preceding output autoformer; in that scenario even neg leg buffer isn't needed; AVC connected in normal way, top tap fed from positive buffer, selected tap going to positive tap of output autoformer, bottom tap going to GND
2. if strictly using Bal inputs, AVC preceding output autoformer; top tap fed from positive buffer, bottom tap fed from negative buffer directly connected to neg tap of output autoformer, selected tap going to positive tap of output autoformer; that way sumation of two phases done in output autoformer
option one clean logic as whistle, option two being sorta patchwork
I've ordered two of these:
I hope so these will be overkill for the task.
| TTSAS0040 - SUPREME AUDIO grade transformer TSAS40VA - voltage to 50V Output voltage: 2 X 20 V; Mounting pad: Side-wiring plate #08 |
I would like this to be the most professional I have ever built.
Obviously I will build it at the kitchen table.
Obviously I will build it at the kitchen table.
Is this available in SE version? I was wondering if it would have the little holes for selector knob. If so, I am ordering now!
Thanks,
Russellc
I see the single ended version but no pic. I assume it also has holes for selector's leds? Is it Black like the balanced version?I assume? dont see choice when adding to cart
Thanks,
Russellc
Thanks,
Russellc
More pictures can be found here https://www.diyaudio.com/community/...re-register-your-interest.390509/post-7337790
The SE version I got from Modushop has holes for balanced version. I mounted the RCA sockets on a PVC board. If you want, I can send a picture of how it looks like.
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