Preamps similar to Glockenklang?

[Passinwind]

I took at stab at measuring both the two band and three band Glocks today. For whatever reason they aren’t playing nice with either of my RTA rigs, so it appears I’ll probably have to throw some other buffer or preamp in the mix. But I was able to look at the frequency response in the old school way, with an oscilloscope and DMM. That 18kHz spec looks to be the upper shelving knee, and there’s still a little boost increase happening to up above 20k. And then the shelf is beginning to drop off at up to at least 40k. The lower knee looks to be a lot lower than I expected (+3dB @ 2k or less) and I’m not sure I believe those measurements just yet. More to follow…

 

[Passinwind]

OK, maybe just an impedance issue with my RTA attempts, or simple operator error. In any case, I finally got it done:

Click to enlarge. Two band version, knobs at noon, both full up, both full down. Lower treble hinge is +3dB at 1.7kHz with turnover freq at 700Hz. I can't find the actual treble peak because of the brickwall filter on my soundcard at ~22k. If we use the 1/2 way between the bottom and top method of specifying shelving frequency, I'd call this ~5-6k for the treble frequency, maybe 8k tops. But as I seem to keep saying, there are quite a few ways to quantify it. 18k just might be the -3dB point below the shelf though, which would jibe with a proper German engineer's textbook spec.

 

[silky smoove]

OK, maybe just an impedance issue with my RTA attempts, or simple operator error. In any case, I finally got it done:

View attachment 7436871

Click to enlarge. Two band version, knobs at noon, both full up, both full down. Lower treble hinge is +3dB at 1.7kHz with turnover freq at 700Hz. I can't find the actual treble peak because of the brickwall filter on my soundcard at ~22k. If we use the 1/2 way between the bottom and top method of specifying shelving frequency, I'd call this ~5-6k for the treble frequency, maybe 8k tops. But as I seem to keep saying, there are quite a few ways to quantify it. 18k just might be the -3dB point below the shelf though, which would jibe with a proper German engineer's textbook spec.

Excellent work. That 18khz control is quite a shelf given how low it dips.

 

[Passinwind]

Excellent work. That 18khz control is quite a shelf given how low it dips.

Yeah, that’s a lot of area under the curve/power density above 8k, which is most likely why it sounds so unusual.

 

[Phil Mastro]

Click to enlarge. Two band version, knobs at noon, both full up, both full down. Lower treble hinge is +3dB at 1.7kHz with turnover freq at 700Hz. I can't find the actual treble peak because of the brickwall filter on my soundcard at ~22k. If we use the 1/2 way between the bottom and top method of specifying shelving frequency, I'd call this ~5-6k for the treble frequency, maybe 8k tops. But as I seem to keep saying, there are quite a few ways to quantify it. 18k just might be the -3dB point below the shelf though, which would jibe with a proper German engineer's textbook spec.

Hm. Yes yes, verily.

Honestly I understood very little of this when I first read it. Thanks for your investigation, and forcing me to learn some stuff about audio signals.

In other news...

It is going to be hard to justify spending more $$ on preamps at this point, so the quest will at best be put on hold for now.

I just purchased a GregoryPreamp GBP3. I'll report back once I've tested it out.

 

[Passinwind]

Hm. Yes yes, verily.

Honestly I understood very little of this when I first read it. Thanks for your investigation, and forcing me to learn some stuff about audio signals.

In other news...

I just purchased a GregoryPreamp GBP3. I'll report back once I've tested it out.

I just throw the info out there, it's up to each person whether to care or learn more about the engineering conventions.

New one on me, hope it works well for you. I've kind of stopped keeping track of all the many newer builders by now since I roll my own and am no longer in the business.

 

[Phil Mastro]

So I received the GBP3 in the mail a few days ahead of its expected arrival, which is always nice, and I wired it up in my ugly temp stompbox. Here's the low down:

GregoryPreamp GBP3 Set 1​

• Bass: 40 Hz +/- 18 dB
• Mid: adjustable 400/600/800 Hz +/- 12 dB
• Treble: 6500 Hz +/- 18 dB
• I saved 25$ USD to get the unwired kit. I managed to wire everything on my first try (shocker there, really), and as it is it's about as messy as a Delano or any other prewired harness. If you're good at planning, you can send a pdf or a picture of the cavity with measurements, and Grzegorz will wire it up for you nice and clean. I'm not that organized unfortunately. It also comes in different knob configuration to suit your needs. Pretty nice.
• Tone-wise, it's the closest I've found to the Glock. It definitely has more bass boost, but I was able to get really close to my Glock tones with it. The mid switch is pretty subtle, it's not as obvious as the ones on the Delano or Bartolini NTMB. I don't think the mids sound quite as sweet as the Taurus, but it's still pretty good. It's also the quietest out of all the new ones I got. Maybe I just did a better wiring job.
• 150$ USD shipped, with taxes and everything it came down to about 265 CAD.

So yeah, quite happy with this one.