HH Scott 299C

[lastshooter]

My first tube amp and new to them and have a couple questions. HH Scott 299C and Klipsch Forte II speakers with Crites crossovers.
First, I see a high and low for magnetic cartridge for phono connection. I will be using a Shure V15 Type III and from what I researched is 3.5 ms and would be considered low after reading that 6ms is where one decides low or high.
Is that correct?

Secondly I read here that Scott amps are not compatible with modern tape decks. Modern being my question. The post stated that it was due to line input impedance not below 100k?

I have a Nakamichi 600 cassette tape deck and can not find any reference to "line input impedance" for it.
Compatible or is it not as the deck is circa 1975 so not too much modern for the 1961/64 ish 299C?
Thanks and anyone with Forte II and a 299C please chime in on how do you like?

 

[anatech]

Hi lastshooter,
I think you mean mV, not ms. Is there any reference to cartridge load? Your magnetic cartridges would prefer about 47 Kohms.

"old" tape decks were designed for 10 Kohms loading, new ones 50 Kohms loading. The older tube equipment typically runs 100 Kohms input impedance, but that is only going to be an assumption. This will not cause any problems for an old or new tape deck. Relax.

-Chris

 

[lastshooter]

doh! yes millivolt!
Only reference is the output voltage I would copy and paste but the user manual from HHScott 1964 is .pdf and will not allow.
Only states 6mV and below connect to low and 7 and above connect to high.I googled the V15 III and found the 3.5mV spec.

I kinda felt the deck would be ok and was just gonna grip it and rip it but then again my luck sometimes just sucks lol

 

[PH104]

This might help.....

 

[PH104]

Never used the Scott 299 but the Crites crossover was a big improvement for my Forte II's.

 

[lastshooter]

I do see 100k for the tape deck and .47 Koums for phono on the schematic, question is mV and a Shure V15 Type III. I feel it should connect to the low terminals and suppose it would not hurt anything and if sound is wrong then go to the high terminal.
I mean Ima n00b for tube lol ala vintage on top of that

 

[lastshooter]

Yes the Crites crossovers were much better as were the titanium domes. I done that on a pair of K4's as well.

 

[cogsncogs]

The post stated that it was due to line input impedance not below 100k?

I have a Nakamichi 600 cassette tape deck and can not find any reference to "line input impedance" for it.

Input Impedance = 50k
The will be some low frequency roll-off and an increase in distortion, assuming you want to record from the 299C's record out jacks, such as from the phono preamp. You could install a 47k resistor in-line with the inputs of your Nakamichi, which will get you close to the recommended load impedance, but with a 6dB loss.

 

[PH104]

I think mag low would be right for your Shure. That's 47k input impedance without going through a voltage divider. I'll check out the Ti domes - thanks for that.

 

[lastshooter]

Input Impedance = 50k
The will be some low frequency roll-off and an increase in distortion, assuming you want to record from the 299C's record out jacks, such as from the phono preamp. You could install a 47k resistor in-line with the inputs of your Nakamichi, which will get you close to the recommended load impedance, but with a 6dB loss.

will just mess around with it once I get it all up and running and come to the "record" part of it all.
If it's not too bad then all might be aok.
Can always record elsewhere and just use playback.

 

[lastshooter]

Input Impedance = 50k
The will be some low frequency roll-off and an increase in distortion, assuming you want to record from the 299C's record out jacks, such as from the phono preamp. You could install a 47k resistor in-line with the inputs of your Nakamichi, which will get you close to the recommended load impedance, but with a 6dB loss.

Hmm...
Or perhaps a tape deck from that era?
reel to reel even...
I wonder how one would look for such an animal? Meaning would all tape decks in the early t0 mid 60's era be in that range for the Scott?

 

[anatech]

Hi lastshooter,
Don't worry about the input impedance of the tape decks. Any possible increased distortion will be tiny, minor, undetectable. Just plug your turntable and tape deck in and enjoy your equipment.

PH104 is correct about your turntable, and if you plug it into the wrong jacks for level, zero damage will occur.

Hi cogsncogs,
Adding a 47K resistor in series is completely unnecessary. In fact, you would probably increase any pickup of radiated noise in the area. The actual output impedance is likely a great deal lower than 100 Kohms. Even if it was 100 Kohms, any signal loss or distortion wouldn't matter given the equipment involved. Everyone can relax now.

-Chris

 

[lastshooter]

Hi lastshooter,
Don't worry about the input impedance of the tape decks. Any possible increased distortion will be tiny, minor, undetectable. Just plug your turntable and tape deck in and enjoy your equipment.

PH104 is correct about your turntable, and if you plug it into the wrong jacks for level, zero damage will occur.

Hi cogsncogs,
Adding a 47K resistor in series is completely unnecessary. In fact, you would probably increase any pickup of radiated noise in the area. The actual output impedance is likely a great deal lower than 100 Kohms. Even if it was 100 Kohms, any signal loss or distortion wouldn't matter given the equipment involved. Everyone can relax now.

-Chris

Thanks!

 

[phase]

I recall mine having a phono input, which was best left to just that, and the others, which would take whatever inputs without any fuss. Mine came from my dad, who got it from the defunct sound lab at Governors State University in Illinois around 1971.

 

[lastshooter]

I recall mine having a phono input, which was best left to just that, and the others, which would take whatever inputs without any fuss. Mine came from my dad, who got it from the defunct sound lab at Governors State University in Illinois around 1971.

The issue(s) are seperate. One is for the tape input and is somewhat not compatible with tape decks manufactured later on. From what I read not that much later say 66ish, it would be tape deck specific as to what line input specs are.

As for the phono inputs for the HH Scott amps of this era and more specifically the 299C(1961).
There are 2 separate phono inputs Mag 1 and Mag 2. One is labeled "High" and one is labeled "Low"
The manual states that 6 mV output for a magnetic cartridge and lower connects to the Low with 7 mV and above to High.
In my case a Shure V15 Type III the output is 3.5 mV.

I have never came across this and why I asked about it. It seems that there was issues occuring when using high output cartridges causing distortion and this was a feature to eliminate that in that era. All kinda Greek to me as never payed much attention to output. I'm a 70's SS type lol

 

[anatech]

Hi lastshooter,
Back when this unit was manufactured there was importance placed on having equal volume for all sources. Some preamps had level controls on the inputs in addition to the front panel controls. I suspect that the two phono positions are addressing that issue than anything technical in nature. Remember that the phono stage tubes run at much higher voltages than anything solid state (on average, the Marantz 3650 runs the phono stage at +/- 35 VDC!). Even a much higher output cartridge is highly unlikely to clip the a tube phono stage.

-Chris

 

[lastshooter]

Hi lastshooter,
Back when this unit was manufactured there was importance placed on having equal volume for all sources. Some preamps had level controls on the inputs in addition to the front panel controls. I suspect that the two phono positions are addressing that issue than anything technical in nature. Remember that the phono stage tubes run at much higher voltages than anything solid state (on average, the Marantz 3650 runs the phono stage at +/- 35 VDC!). Even a much higher output cartridge is highly unlikely to clip the a tube phono stage.

-Chris

Thanks Chris much appreciated info!
I always like to know as much as I can about features and why they came about!

 

[lastshooter]

Well the 299C was fired up yesterday and all was aok!
My first venture into tubes!
I was using a 1979 Yamaha CR-2020 SS which is a mighty fine receiver and a brute at 105 watts per channel and that good ol' 70's sound. A very solid receiver too at 39 years.
I have a jazz demo LP made by Yamaha, with all Yamaha studio equipment with every instrument made by you guessed it Yamaha! Just to showcase Yamaha Natural sound receivers!
The 1961 H.H. Scott 299C @ 28 watts per channel just blew it out of the ballpark!!! I mean pwned that Yammy in every aspect.
Unbelievable!
Now to get that HH Scott tuner fired up!

 

[juwantoharun]

Hi all master, I'm from Indonesia. I'd buy a Scott 299C in broken condition. I think maybe i can fix it. but unfortunately i found that one of OT and PT was burned and one of 7591 tubes broken. so i think that impossible to built back. I want to build a new one, maybe some advice from you all, which is better sound, Scott 299C or Dynaco ST70?

 

[Eli Duttman]

The damaged O/P transformer requires a custom rewind and you will have to find somebody "local" to do the work. Buying a pair of custom wound O/P transformers and selling the working Scott original is (IMO) a good idea.

The power transformer can be replaced with an "off the shelf item". The "Dynaclone" ST70 replacement power transformer can be adapted to the task at hand. The fact that 7591s draw less heater current than EL34s is exploited. A single 6.3 VAC winding of the ST70 trafo is capable of energizing all 6 299C power section tubes. Schottky diode "full wave" voltage double and 7812 regulate a DC supply for the 4X 12AX7 preamp tube heaters, that is energized by the 2nd 6.3 VAC winding. A 3rd Schottky diode is used to 1/2 wave rectify the bias tap to obtain that negative voltage.

Current production 7591s are intolerant of the liberties that were taken by manufacturers in regard to the grid to ground resistance limit. Replace resistors 48, 49, 148, & 149 in the 299C schematic with 1% tolerance metal film parts, like these. The OEM 330 Kohm carbon composition parts are a tad big and likely have drifted upward, with the passage of time.

The ST70 is a power amp and the 299C is an "integrated" amp. "Apples and oranges." Both are nice units from the "Golden Age".