Intact Audio

Hi! Multisection bobbins are used to connect windings in series to add inductance and cut down capacitance. If you attached two inductors, that are wound on two separate cores in series, would that have the same effect in cutting down capacitance? I can't be as easy as adding one of your L2 chokes i...

Hey, Inverse RIAA is a software filter. It doesn't have the Neumann time constant. Currently I am still using the Allnic/Acoustic Dimension LCR in a can, which is potted, so I can't change the innards and add R6. But I did try my luck with an RC bridging the filter and that (360pF + 39k) did away wi...

@Dave: Sorry for my last (confused) Emails. I should have shut up and measured first. To everyone of the smart people discussing LCR filters here: I built a phono pre: Triode -> 4:1 interstage -> 600R LCR -> 1:4 step up -> triode -> 1:1 output. Dave wound the 4:1 interstage and in circuit (measured ...

Ok, that makes sense.

Hi! I scaled up Gerd Reinhöfer's iteration of the 600R LCR to 1k8: Bildschirmfoto 2023-08-02 um 19.19.27.png @dave slagle: I entered 120R as series resistance for L1 and 35R for L2. If I ordered the inductors from you (80% Ni, silver wire), do you have any realistic estimates for the parasitics to g...

"Now two transformers with the secondaries in series would be my goto solution at this point." I am currently using a summing transformer at the input of my mono amp. Would two transformers with the secondaries in series give a 1:2 stepup? If I ordered two 1:1 full range input transformers...

My case: manganin film shunt resistor, 6dB serial crossover, 211 output tube through nano transformer His case: manganin wire trimmer, dbx DSP crossover, safety cap before autoformer, 1875 chipamp (His crossovers are still in the figuring things out phase, which is a lot easier with a DSP. The autof...

Yesterday I was at a friends place who has a similar setup as mine. We restacked his tweeter speakerformers and didn't notice any change.

Level was the same. When I choose the "display multiple graphs" option they are spaced apart and there was one with a measurment glitch in between that I deleted. I'll hook up a chipamp and measure again.

SlagleformerVergleich2.png Top: autofomer as delivered 3x3 stacking, in circuit, mid driver replaced with 16R resistor. Bottom: stacked 1x3x3xrestx3x3x1 Level is the same, this is how the software displays multiple graphs. Driving it from a 50R output impedance generator probably makes this all mon...

Changed stacking around a bit more and arrived at 2x2xrestx2x2. My narrow sweet spot got narrower than it was before with even less of a grey area. Stero effect more defined, more details. And that silver sound you get when changing from an AVC with copper to silver windings. That unique type of sof...

Is it just about changing the lf rolloff due to a change of inductance or also trading that for a linearized BH curve? I restacked the laminations in the tweeter attenuator to 3x3xrest of themx3x3. As it took me around 24h between listening, starting to restack and finishing and listening again the ...

Yeah, of course, just try it out, measure and listen. But I'm lazy and busy, so: has any of you ever experimented with restacking speakerformers? With my AVCs I feel without experimenting with different stackings I wouldn't have gotten half of what they offer. What does the math say in that case? Wi...

How did you go about changing zenith without changing overhang? The old loosen one screw, adjust and as the change in overhang is so minute don't care about it?

FWIW: I recently changed from a Sowter 9335 to a Slagle AVC. Both at the output of my phono stage, E55L into a 1:1 transformer. After removing the Sowter I put in clip leads to make restacking the AVC and comparing to the Sowter easier. As delivered with the 1x1 stacking the AVC had issues with the ...

I received my AVCs with a 1x1 stacking (0 to ground this measured 76H @1kHz??). Source is a triode strapped E55L through a 1:1 output transformer, so Zout about 600R. With the 1x1 stacking bass seemed surprisingly weak given this yields maximum inductance. Listening to Madvillain's Madvillainy 12&qu...

Cool! I'll get in touch once I'm done DSPing the drivers into submission and know my numbers.

Ok. Say if I needed two inductors for low pass filters at somewhere around 6.5mH @ 800Hz and 8kHz, what type of core would you suggest and is there a chance to wind these guys with a DCR below 100 mΩ? And to get back to the topic of attenuators, if I built a bandpass filter for the mids with a 12dB...

Hi, Dave mentions that the choice of impedance setting via a parallel resistor is a way to crank up impedance to use smaller capacitors. How about using it to match impedances at the crossover point? Say you build a two way speaker, cross at 1k5 and the woofer is at 7 Ohm and the tweeter at 9 Ohms. ...

drh wrote:gain range say from -50 to plus 3 or plus 6?

Hi!
That's quite a range. Out of curiousity, are you using them with various sources and power amps that have very different gain levels or do you change from ultra low to ultra blasting listening levels depending on music/time/gusto/.... ?

There are some design points in there that seem a bit strange and/or limiting, like the EZ81 rectifier. By "choke filter" you mean a choke input filter? At least I hope so. Why do you want to heat the input stage with DC and the output with AC? I recommend you contact Thomas Mayer (www.vin...

"All the parts have to be put together at some point." Also the parts and the people to enjoy them have to be put together. In the upcoming future my girlfriend and me will have our first child and the question came up how to keep the child safe from kilovolt anode supplies (open mains tra...

Sorry, I am a bit scatterbrained due to the heat here (thermal noise inside my brain??) and mixed up thermal and Barkhausen. Still I believe the thermal noise to be the least factor regarding the differences in resistive and inductive attenuation. I thought I was talking about just the thermal noise...

I don't think Barkhausen noise is the crucial factor here. The advantage of an AVC is low noise, as compared to a resistive attenuator. With an AVC, the noise is so low (apparently equivalent to less than a 50 ohm resistor), that you should be able to hear deeper into the music than with a 10k pot, ...

dave slagle wrote:I think it is just about the best you are going to get a cathode follower to sound.

dave

Let's say I'd want to use an output transformer with a DHT cathode follower with let's say 500mA filament current. Would an opt be possible?

Hi! I went through ideas of buiding a phonostage using a pentode input with Frank Blöhbaums "best pentode" circuit. That way it might be possible to do all the amplification needed with one tube stage and use another tube as a buffer stage. All cathode followers I have seen so far use an ...

Putting in cathode resistor bypass capacitors brought some changes. On the Ba and 801A it did nothing, when installed on the 211's Rk the wideband noise turned into some motorboating at 2-3 Hz. Removing the original filament supply and hooking up a lab supply to each filament changed nothing. I'll s...

vinylkid wrote: are these units' lams stacked differently from each other in stock form?

How do you know the second hand one is still in stock form? Why don't you just have a look how both units are stacked? That seems the only and easiest way to get some answers.

As I tried to explain earlier I am not using the 1/2 B+ arrangement anymore but put in another independent power supply. Having the chokes in the center tap leg didn't work; for some reason this gave me a positive instead of a negative grid voltage on the 801. When you build a dc amp with stacked su...

Howdy! You are coming back to the original question here. This was the original anode supply for the 211 and the 801A giving B+ and 1/2 B+. I never got this to work dc-coupling the Ba to the 801A (full output static noise), so I disconnected the 1/2 B+ to the 801A, put in a lab supply and the noise ...