"Back in the USSR"
- a vintage package from Russia
Thanks to Mike, alias Sidash Mihail Vladimirovich/Moscow

Hi Mike,   THANKS! What a surprise. All items received in good condition and I've prepared a website for a coming article. I guess the brown caps are PIO and the other caps - alu in teflon? The cable? Looks like and excellent speaker cable. The 5GDH4 drivers are fun. I can't believe these are all NOS. These drivers appear to never have been mounted. I did a very quick test and they have a reasonable frequency response - no nasty peaks. Fs is around 100 Hz and the most (troublesome) thing is the Qt > 3. Never before had drivers with as low electrical damping as these. This creates a huge peak at point of resonance (100 Hz). Calculated sensitivity is around 84 dB - and measurement suggest something around 85-86 dB/2.8V. Would you have time to write a few lines on these drivers. I've searched the web and didn't find any references at all on these drivers. It would be nice to have a little background material for the article.
Mike, thanks again! Troels

Hi Troels.
Brown caps are NOS oil & alu.foil + paper. I use them in tube amps (as shunt) or in crossovers to make a sound softer. The others caps are alu + silver & fluorocarbon polymer. They are very popular in Russia but quite rare. I send you a photo of their packing in order to show you the level of their assembling. I use them everywhere - as shunt, as interstage , as shunt in crossovers, try to use them , I think you will love it. I like them more than MultiCap RXT. This cable is from …. aviation =). It is high-frequency silver coated copper + teflon cable. It is possible to use them as speaker cable or as assembly cable in amp.
5GDH4 drivers are all NOS. I took them from the new box. They were made in 1985. Usually we use them in open box or in open baffle. It is better to use more than one driver in one speaker. Try to “work up” them carefully by 40-50 Hz sweep tone for several hours. It will decrease Fs. Our experts say that when more than one driver is used in speaker, their total Fs gets smaller. Qt > 3 isn’t good thing but it makes very interesting bass in open box construction. Try to measure Qts after some time working.
It is possible to use some types of “cone impregnation” to make driver more rigid but this is not my way, one thing is possible to do, is to use silicon mastic to make drivers basket more muffled. I think that these drivers are not very universal (in music), but vocal is very impressive. In my case – when I listen hard rock a use EXEL + ribbon drivers and transistor amp. When I listen “vinyl” I use tube amp and these drivers =)
Best regards, Mike

Hi Mike,
Thanks for the info. Very useful. Have added it to the website.   I've just installed the alu/silver/teflon caps in my Transcendent RIAA and they're excellent, probably better than the Jensen copper foil caps I've used so far. The values are perfect for this application.
I'll try the 5GDH4 drivers on an open baffle some day, probably in a MMTMM set-up and use some bass driver up to 150-250 Hz. The sensitivity should end up around 90 dB from such a set-up. We'll see. This is likely to be a summer's fun-project.

- more to come - some day.

The 5GDH4 drivers

pics provided by Mike or found on the web

Measurements 5GDH4

Left: SPL/1 meter/2.8 volts. Right: Same, only 100-10000 Hz range.

Left: Impedance free air. Right: Nearfield response of 5GDH4 driver.

5GDH4 TS-data.

By the way -
- have you ever seen a 1 uF capacitor like this? Mike send me these.
The 0.1 uF caps (above) have found a steady home in the
Transcendent RIAA, and
these 1 uF beer cans will be tried in the
Grounded Grid line stage. Will they beat the silver/gold caps?
The 0.22 uF will be tried in a coming 300B SET project.