Great
Send the schematic . I never turn down one.
Don
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Great
Send the schematic . I never turn down one.
Don
Bummer. It would be fun to the the difference. I believe the compression driver in the 604 is based on the 802 drivers, and those cross at 700Hz in an A7 system. Would it be possible to give both drivers a 1K test tone with no filtering to illustrate the time smear?Quote:
Originally Posted by Alien_Shore
For some background, I'm working on re-creating the Urei 801B duplex which was developed by United Recording Electronics after they ceased using the 604 based diver due to QA issues in the early '80s. The picture in my avatar are some of the early horns for my project based on the Urei horn. Their Time Aligned? crossover is quite similar to the filter Mr. Patton is using, although I think with modern testing Don may be attaining higher accuracy that the production Urei units.
eso
Mike
I can put one together sunday , you would have it next week .
Don
Here are the same measurements, with a bit more sensitivity on the scope:
LF only:
https://www.hostboard.com/forums/hbm.../2012/10/1.jpg
HF only:
Combined:
https://live.staticflickr.com/65535/...32a063fd_c.jpg
No joy on the dual channel triggering. I did manage to get all three devices going with a USB bus, but the scope software still only will look at the internal signal generator and the probe. So with that experiment I was at least able to see the electronic trace of the test chirp as it came out of the amp into the filter, but just cant put anything else on the display with it. I plan on building another tube amp this winter, so I'll be on the lookout for a standalone scope or some better software.
Thanks Don - I received the N1500-A clone in the mail today.Quote:
Originally Posted by donaldpatten
I'll work on putting together some tests...
Do you have your E in a cabinet yet?
oh hell no. I've been busier than a one-armed paper hanger.
Although my woodworking shop construction project is moving along! The concrete guys came today and poured the slab.
Ran a quick impedance sweep comparison of the N1500A clone that Don built along with the Time Delay filter.
These are sweeps with the 604E woofer attached only. Remember that my 604E is reconed at GPA with 8 ohm parts.
In this graph, the red/blue lines are the time delay low-pass filter, the green lines are the N1500A clone with the HF shelving control set at mid-point. The cursor is set at the crossover point of 1500 Hz.
https://live.staticflickr.com/65535/...798f6e80_b.jpg
The shelving control on the N1500A clone works as you'd expect from looking at the schematic. As you decrease the HF attenuation, the woofer rolls off more quickly, and vice-verse.
Here are a couple more impedance sweep graphs.
This is the HF tweeter barefoot (green), along with the zobel (magenta) I'm working on:
https://live.staticflickr.com/65535/...01517819_c.jpg
I need some smaller resistors and caps to fine tune this a bit further, but it's getting there. I had to do some un-natural series/parallel joins of caps to get at this arrangement since all I had on hand were 1 and 2 uF caps. This is using 12 ohms R and 1.5 uF C. I think I need a little bit more R and C to get this thing fairly flat at about 8 ohms. Does anyone know if it is possible to smooth out all those crazy ripples after Fs?